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Walla Walla River Watershed Study Reconnaissance Report |
Table of Contents
Figure 1 - Drainage Areas by Land Mass and Water Volume
Figure 2 - Water Usage in the Basin
Figure 3 - April - August Temperature in Main Stem Walla Walla River Near Touchet, Washington (1950-1996)
Table 1 - Communities in the WWRB
Table 2 - Land Ownership Within WWRB
Table 3 - Walla Walla River Major Tributaries Drainage Areas
Table 4 - Adult Steelhead Count at Nursery Street Dam
Table 5 - Total Storage
Table 6 - Freshwater Life History of Hatchery Spring Chinook Salmon (Carson Hatchery Stock)
Table 7 - Costs for Storage Sites
Table 8 - Possible Small Storage Sites
Table 9 - Matrix of Impacts
Table 10 - Construction Costs for Potential Sites
Table 11 - Costs for Lining
Table 12 - Salmon Reintroduction Alternatives
Table 13 - Benefit Cost Ratio of Previous Alternatives
Table 14 - Current Reconnaissance Study Flood Damage Reduction Project Benefit Cost Ratio Comparison
Plate 1 - Base Map
Plate 2 - Regional Access and Population
Plate 3 - Regional Land Use and Cover
Plate 4 - Land Ownership
Plate 5 - Hydrology
Plate 6 - Regional Precipitation
Plate 7 - Dewatered Streams
Plate 8 - Corps of Engineers Projects
Plate 9 - Public Water Entities
Plate 10 - Stream Diversions
Plate 11 - Fish Passage Impediments
Plate 12 - Steelhead Distribution
Plate 13 - Bull trout Distribution
Plate 14 - Setback Levees
Plate 15 - Levee Removal
Plate 16 - Possible Storage Sites
Plate 17 - Water Exchange
Plate 18 - Irrigation Canal Efficiency
Plate 19 - Irrigation Canal Migration
Plate 20 - Salmon Facilities
Appendix A - Hydrology
Appendix B - Supplemental Planning Aid Report
Appendix C - Aquatic
Appendix D - Real Estate
Appendix E - Cost Estimate
Appendix F - Letters
Appendix G - References
Appendix H - Contributors
The purpose of this Walla Walla Watershed General Investigation Reconnaissance Report by the U.S. Army Corps of Engineers (Corps), Walla Walla District, was to evaluate the following: (1) Water resource issues (i.e., issues associated with flood damages or possible environmental restoration) and (2) potential project alternatives for solution of those problems within the Walla Walla River Watershed. [NOTE: Walla Walla River Watershed and Walla Walla River Basin (WWRB) are to be used interchangeable.] Federal involvement in the resolution of the identified water resource problems is contingent upon the following factors: (1) The environmental impact, technical feasibility, and regional and local acceptance of the potential project alternatives; (2) identification of a local sponsor who is willing to pay for part of the cost (cost-sharing); and (3) an incremental-cost analysis of the benefits if the project purpose is for environmental restoration. If the project purpose is flood damage reduction, the benefits of the potential project alternative must outweigh the costs (benefit:cost ratio). The reconnaissance study will determine if the Federal Government should proceed to the next step, the feasibility phase, in the resolution of the identified problems.
Additionally, the Corps, as part of the Federal Government, has a trust responsibility to Native American Tribes under the Treaty with the Walla Walla, Cayuse, and Umatilla Indian Nations; Walla Walla, Washington; June 9, 1855. Part of the reconnaissance study is how the Corps can address responsibilities to provide salmon for the historical Native American Tribes in the Walla Walla River Basin (WWRB); Walla Walla, Cayuse, and Umatilla.
The reconnaissance study evaluated flood damage reduction and ecosystem restoration issues relative to water resources in the WWRB. However, environmental restoration in the WWRB was the primary focus. It is increasingly rare to find a traditional Corps project that has a positive benefit:cost ratio and/or a sponsor willing to pay part of the cost of a project. The funding for this study was established before the February 1996 floods of the WWRB; it was recognized that there were water resource problems in the basin prior to this flood event. The floods caused heavy damages to the WWRB communities and residents. While significant to the area residents, the lands and properties damaged by the flood do not represent a high-dollar value that would justify a traditional, structural solution (e.g., dam, levee, etc.). The Walla Walla District Reconnaissance Report, Walla Walla River Basin, Oregon and Washington, April 1992, determined that, on an economic basis, it was not possible to justify a potential traditional project alternative with associated high-construction costs. It is unlikely that these conditions have changed since this 1992 determination.
Additionally, the Corps, has changed the manner in which it evaluates flood damages: In the past, the Corps addressed only flood control but now also addresses the larger scope of flood damage reduction. While traditional flood control measures (i.e., dams, levees, and channelization) can still be implemented, the Corps can also examine other measures including the removal of structures from the floodplain. The current goal is not necessarily to control floods but to prevent damage caused by flooding.
Many of these new measures are beneficial to environmental resources. For example, measures such as removal of development in the floodplains and setback levees can provide benefits to riparian zones in the WWRB. Consequently, the reconnaissance study concentrated on measures having an environmental benefit while at the same time reducing flood damages in the WWRB.
The reconnaissance study of the WWRB (covering parts of Washington and Oregon) was conducted under the authority of the resolution by the Senate Committee on Public Works adopted July 27, 1962 (Columbia River and Tributaries).
The WWRB is located in southeast Washington and northeast Oregon. It is a fan-shaped basin (see plate 1) encompassing 4 553 square kilometers (sq km) [1,758 square miles (sq mi)]. Of the total WWRB, 3 309 sq km (1,278 sq mi) or 73 percent is located in Washington; 1 243 sq km (480 sq mi) or 27 percent is located in Oregon. The eastern one-fifth of the WWRB lies in the steep, lightly timbered western slopes of the Blue Mountains within the Umatilla National Forest. The remainder of the WWRB consists of moderate slopes and level terrain.
The WWRB encompasses five counties: Umatilla, Union, and Wallowa counties (Oregon); and Walla Walla and Columbia counties (Washington).
The WWRB is part of the historical territory of the Walla Walla, Cayuse, and Umatilla Indian Tribes. The land was ceded to the Federal Government under the Treaty of 1855. However, the Tribes still have reserved rights for these lands that include the harvesting of salmon in the WWRB.
The WWRB is comprised of a limited number of urban areas. The largest population is located in Walla Walla County, Washington; the second largest population is located in Umatilla County, Oregon; and the third largest is Columbia County, Washington (see plate 2). According to the 1990 census, approximately 70 percent of the residents of Walla Walla County live in the greater Walla Walla urban area, which is defined as Walla Walla and College Place, Washington. Distribution of population is shown on table 1.
| Table 1 - Communities in the WWRB | |
|---|---|
| City | Population¹ |
| Walla Walla, Washington | 28,860 |
| College Place, Washington | 6,166 |
| Milton-Freewater, Oregon | 5,576 |
| Dayton, Washington | 2,525 |
| Waitsburg, Washington | 1,028 |
| Weston, Oregon | 632 |
| Touchet, Washington | 410 |
| Prescott, Washington | 293 |
| Dixie, Washington | 200 |
| Lowden, Washington | 50 |
| ¹U.S. Census Bureau estimates, 1994. | |
Agricultural production is the dominant land use in the WWRB; 2 658 sq km (1,026 sq mi) or 58 percent of the land use (see plate 3). The area’s economy is predominantly reliant upon agriculture. Agricultural varies from dryland (i.e., wheat farming) to irrigated (i.e., orchards). Forest land makes up 1,114 sq km (442 sq mi) or 25 percent of the WWRB. Range land accounts for 751 sq km (290 sq mi) or 17 percent. Land ownership within the WWRB is broken down as follows (see plate 4 and table 2).
| Table 2 - Land Ownership Within WWRB¹ | |||
|---|---|---|---|
| Land Ownership | Square Kilometers |
Square Miles |
Percent of Basin |
| Private or Other | 4,060 | 1,568 | 90 |
| Federal | 427 | 164 | 9 |
| State (Oregon and Washington) | 65 | 25 | 1 |
| ¹Corps of Engineers, Walla Walla district corporate GIS database system, 1997. | |||
The WWRB is bordered by the Snake River Basin on the north, the Tucannon and Grande Ronde Basins to the east, and the Umatilla Basin to the south.
As seen in plate 5, there have been, at one time or another, 25 United States Geological Survey gauging stations in the WWRB. Currently, however, only three gauging stations are active. Little or no water quality data has been collected for most of the stream reaches throughout the WWRB. Only a few stream reaches have detailed morphology data available. The lack of water quality and channel geometry data limited the analysis for this reconnaissance study.
The Walla Walla River originates in the Blue Mountains at an elevation of nearly 2 000 meters (6,500 feet) and flows through narrow, well-defined canyons. After it flows out of the mountains, it goes through broad valleys that drain to low, rolling lands. Table 3 summarizes the drainage area (includes the entire sub-watershed) and runoff data for major tributaries of the Walla Walla River.
| Table 3 - Walla walla River Major Tributaries Drainage Areas | |||
|---|---|---|---|
| Drainage | Drainage Area (sq km) |
Drainage Area (sq mi) |
Average Annual Runoff Volume [acre/feet (AF)] |
| South Fork Walla Walla near Milton-Freewater, Oregon | 163.17 | 63 | 139,000 |
| North Fork Walla Walla near Milton-Freewater, Oregon | 88.06 | 34 | 39,200 |
| Mill Creek at Walla Walla, Washington | 249.00 | 96 | 66,000 |
| Touchet River at Bolles, Washington | 935.00 | 361 | 180,300 |
| Local Runoff (remainder of basin) | 2857.00 | 1,103 | 37,500 |
| Total (Walla Walla River near Touchet, Washington) | 4,292.23 | 1,657 | 462,000 |
Figure 1 shows in quantitative form what is common knowledge throughout the American West; a disproportionate amount of water falls on a small section of the watershed. For example, local land occupies 66 percent of the total surface area in table 3. However, it only provides 8 percent of the water yield of the basin. Conversely, the South Fork of the WWRB makes up 4 percent of the land in the watershed while it supplies 30 percent of the water yield. For further information, see appendix A.
The precipitation in the WWRB varies dramatically and correlates with elevation (see plate 6). Near the mouth of the Walla Walla River, the precipitation is less than 25 centimeters (10 inches) annually. The amount of precipitation increases with elevation until a maximum of over 100 centimeters (40 inches) accumulates annually in the headwaters of the WWRB.
There are currently only three operational gauging stations in the WWRB: Mill Creek near Walla Walla, Walla Walla River at Touchet, and Mill Creek at Walla Walla.
Plate 7 shows the seasonally dewatered portions of the waterways in the WWRB. This is largely due to irrigation withdrawals from the waterways. There is not enough water in the dewatered sections of the waterways to support any aquatic life during the summer months of most years. This is due to a combination of flows being too low and the temperatures of the remaining water being too high. This dewatering generally occurs, depending upon flows within the waterways, within a June through October timeframe. Extremely wet or dry precipitation years would expand or shrink the timeframe.
The area marked on plate 7 as dewatered has no water, or minimal water, that can support any fish life. This area totals 93 km (50.2 miles) of river. The areas outside of these dewatered sections may support non-native fish species such as catfish, bass, and carp. Only in the upper headwater sections is the water quality sufficient to support native, cold-water species such as rainbow trout, steelhead juveniles, and sculpin.
A combination of dewatering and lack of fish passage, likely, led to the demise of the WWRB salmon run sometime between 1915 and 1925. The last reported salmon run of any size was recorded in 1925. Nielson (1950) reports, "At no time (during irrigation season) since the late 1880’s has there been a flow of water through this section of the Walla Walla River (below Milton-Freewater, Oregon)." Neilson also reports, "Local people report that Nine Mile Falls Dam, built in 1905 near Reese, Washington, was largely responsible for the decimation of chinook salmon runs in the Walla Walla Basin."
As seen in figure 2, the vast majority of water used on the Washington portion of the WWRB has been devoted to irrigation. While the information for water usage on the Oregon side of the WWRB was not available, it could be assumed that the breakdown of use would be approximately the same.
Concern over flooding of communities and agriculture fields has been heightened by the recent flooding that has taken place in the WWRB. In both February 1996 and January 1997, flooding in the upper Touchet Basin led to the loss of property and disruption of the local community. This has led to the formation of an additional flood-control district in the Prescott, Washington, area. More information on flooding is provided in appendix A.
A basalt aquifer underlies the entire WWRB and is part of the layered Columbia Basalt. It is primarily charged by runoff from the Blue Mountains. This aquifer is a series of interconnected lava flows that conduct water in a horizontal direction. However, the lava flows are compressed tightly, and the water is not moved through very rapidly. The direction the water is heading is, generally, northwest toward the Snake and Columbia Rivers. This aquifer has a storage capacity of 4.9 billion cubic meters (m³) [4 million acre-feet (AF)], with only 3.2 billion m³ (2.6 AF) available for use. Annual recharge of the aquifer is approximately 162.8 million m³ (132,000 AF). Of this amount, 120.2 million m³ (97,500 AF) annually discharge laterally into the Columbia and Snake Rivers. Of the 162.8 million, 14.7 million m³ (12,000 AF) are discharged to the gravel aquifer (see below), and 27.7 million m³ (22,500 AF) are pumped to the surface (largely for irrigation) causing water levels to dramatically decline (James, 1992).
A gravel aquifer underlies 48 564 hectares (120,000 acres) of the Walla Walla/Milton-Freewater area. This aquifer is located approximately 65 meters (200 feet) above the basalt aquifer. Between these aquifers is a layer of impermeable clay. The storage capacity of this gravel aquifer is 3.6 billion m³ (3 million AF) with only 124 hectare-meters (1 million AF) accessible for active use. The aquifer is recharged from surface streams, precipitation, and the basalt aquifer. Annual recharge is 218 million m³ (177,000 AF) of which 123 million m3 (100,000 AF) are lost through direct evapotranspiration, 140 000 m³ (113 AF) are returned to the streams, and 314 million m³ (25,000 AF) are pumped to the surface (James, 1992). Therefore, only 639 million m³ (51,887 AF) are actually recharging the aquifer.
Limited information is known about the groundwater resources in the basin, but groundwater tables appear to be generally in the decline.
There are currently six Corps projects that have been completed in the WWRB as follows (see plate 8): Levee construction projects in Waitsburg (1951), Dayton (1965), and Milton-Freewater (1952); Channelization of Mill Creek through town; Bennington Lake Project (1942); and Channelization of Dry Creek on the lower end of the WWRB (1961).
However, a project that is currently in progress on the main stem Walla Walla River is not shown on plate 8. This is the Walla Walla River Fish Passage Restoration Project that is currently being designed. This restoration project relates to the design of a new fish ladder at Nursery Bridge, Milton-Freewater, Oregon. The restoration project is being conducted under the Corps’ Section 1135 authority, Modification of Corps Projects for the Benefit of Fish and Wildlife, and construction is anticipated in 1998 or 1999. This is a cost-shared project with the Milton-Freewater Water Control District acting as the sponsor, with strong support from the Confederated Tribes of the Umatilla Indian Reservation (CTUIR), Oregon Department of Fish and Wildlife (ODFW), and the National Marine Fisheries Service (NMFS).
Plate 9 shows the location of other political entities that are primarily devoted to the issue of water resources. These include one irrigation district while the remainder are involved with flooding issues. The area shaded on the plates shows their areas of jurisdiction.
Background information on WWRB fishery resources and aquatic habitat considerations are provided in the report prepared by the U.S. Fish and Wildlife Service (USFWS), Walla Walla River Basin Reconnaissance Study Supplemental Planning Aid Report, December 1996 (see appendix B). Additional information can be found in the Walla Walla District Reconnaissance Report, Walla Walla River Basin, Oregon and Washington, April 1992.
Aquatic habitat quality in the Walla Walla River and its tributaries has been dramatically impacted by land management practices that were gradually adopted as the region was settled by Europeans. Expansive areas in the WWRB have been brought into agricultural production and timber harvest with several towns being located within the floodplain of both the Walla Walla and Touchet Rivers. Aquatic habitat degradation is most evident in the lower reaches of the main stem Walla Walla and Touchet Rivers.
Aquatic habitat degradation in the WWRB is a direct result of the following factors:
The following is a brief discussion of each of the five factors.
(1) Removal of Riparian Vegetation.
Prior to the advent of current land management practices, expansive riparian zones existed along streams in the WWRB. It is estimated that only about 37 percent of the Touchet River riparian zone is currently vegetated with riparian plants (Mudd, 1975). Along the Oregon portion of the Walla Walla River, 70 percent of the existing riparian zone is in poor condition (Water Resources Commission, 1988).
The value of riparian zones cannot be overstated. Riverine and terrestrial ecosystems are linked, being separated only by a riparian zone. Because of the close connection between the stream and its drainage basin, land uses and management practices such as row crop agriculture, grazing, timber harvest, or road and bridge construction have a profound effect on the aquatic ecosystem. Riparian areas serve as a buffer and very effectively moderate the negative effects of land use practices on the aquatic ecosystem.
Riparian vegetation provides logs and branches that shape channel morphology, retain organic matter, and provide essential cover for salmon and trout. As trees mature and fall into or across streams, their large mass helps to control the slope and stability of the channel, and they help create high-quality pools and riffles. Natural recruitment of large, woody material from the riparian zone is reduced by the reductions in riparian woody vegetation. These reductions are aggravated by intentional removal of logs and root wads that are seen by landowners and local residents as impediments to flow and making flood events worse. However, in many cases, trees in streams are important and often essential for maintaining stream stability (Platts, 1991). Riparian vegetation root systems stabilize streambanks and maintain undercut banks that offer prime salmonid habitat.
Large, woody debris, along with water depth, water turbulence, large-particle substrates, undercut banks, overhanging riparian vegetation, and aquatic vegetation provide cover for salmonids. Abundance of fish in streams has been correlated with the abundance and quality of in-stream cover. When large, woody debris is removed from a stream, the surface area, number, and size of pools decrease and the mean water velocity increases.
Streamside vegetation needs to be vigorous and dense and to have enough species diversity that it can form layers over the ground. Each vegetative form type plays an important role in forming and protecting the aquatic habitat. In some situations, the root systems of grasses and other plants trap sediment to help rebuild damaged banks. During flood events, water moving at high velocity transports large amounts of sediment within the channel. As the flood water rises up and then over the banks, it flattens flexible streambank vegetation (e.g., willows and grasses) into mats that hug and thus protect the streambank from erosion. This causes sediments to settle out and become part of the bank.
Riparian vegetation forms a protective canopy that helps maintain cool, stream temperatures in summer. At present, only a fraction remains of the riparian trees providing shade to the Walla Walla River drainage. The effect of the lack of shading is elevated temperatures throughout the WWRB that appear to be a critical limiting factor in terms of quality aquatic habitat. Although data is limited, figure 3 shows that temperatures in the lower Walla Walla River are generally much higher than accepted passage criteria.
Although no historic quantitative stream physical habitat data exists for the WWRB, it is highly likely that streams in the Walla Walla River drainage, most notably the main stem Walla Walla and Touchet Rivers, have been dramatically altered as a result of destruction of riparian zones. Resultant fish habitat degradation is generally characterized by the following: (1) less in-stream cover associated with large organic debris, underbank cutting, overhanging vegetation, and surface turbulence; (2) fewer slack-water pockets/pools associated with large organic debris; (3) reduced in-stream depth/velocity/substrate diversity; (4) reduced stream productivity resulting from reduced energy input from detritus; (5) reduced intergravel flow results in increased sedimentation (i.e., reduced stream productivity and fish reproductive success); and (6) higher water temperature resulting from reduced shading.
(2) Interruption of Natural Riverine Geomorphological Processes by Construction of Dikes and Levees, Rip-Rapping, and Changes in Channel Geometry (e.g., Channelization).
Natural channel dynamics in the Walla Walla River, as well as most other river channels in the country, have been "controlled" to some extent to accommodate land uses introduced by European settlers. Measures are commonly taken to keep the channel from meandering, or otherwise adjusting laterally, and to prevent overbank flooding. These measures can include construction of dikes and levees, channelization, and riprapping, which are all common in the WWRB. Interference in natural geomorphological processes disrupts channel patterns that are self-developed and self-maintained.
Stream channel patterns, morphology, and other features are determined by the laws of physics. These patterns are directly tied to fundamental variables including width, depth, velocity, discharge, slope, channel roughness, sediment load, and sediment size (Leopold et al., 1964). A change in any one of these variables results in commensurate adjustments in the other variables. These variables are manifest in the form of the following: Lateral channel migration and attendant higher than normal rates of bank erosion and an encroachment on riparian vegetation; abnormal channel degrading and aggrading; increased flooding with lower magnitude base flows; increased sedimentation; and substrate material size shifts.
Although no historic quantitative stream physical habitat data exists for the WWRB, it is very likely that the effects of interruption of geomorphological processes in the main stem Walla Walla and Touchet River channels has had the following effects on aquatic habitat: (1) the channel is less sinuous and the gradient is steeper; (2) the width/depth ratio is higher; (3) there is less pool habitat and more run habitat; and (4) mean sediment particle size is smaller with a substantially higher proportion of sand, silt, and associated cobble embeddedness.
(3) Alteration of Stream Flows.
Diversion of stream flow for irrigation purposes has resulted in reduced flow in the WWRB during the irrigation season; generally late June through October. Plate 10 shows the location of irrigation diversions throughout the WWRB. Evidence of dewatering is most evident in the Walla Walla River in the Milton-Freewater, Oregon, area where it is entirely without-surface flow during much of the irrigation season.
Accuracy of the information on plate 10 is complicated because of the fact that many of the irrigation diversions in the WWRB are not used every year and some of these diversions remain "on paper" even though they may have been abandoned for a number of years.
The most obvious effects on aquatic habitat of stream flow reductions from irrigation diversions in the WWRB are as follows: (1) reduced depth; (2) elevated temperature; and (3) concentration of total dissolved solids (e.g., pollutants, nutrients, etc.).
(4) Construction of Obstructions in the Channel.
Several permanent and temporary diversion structures have been constructed in the WWRB. The locations and descriptions of these diversion structures are indicated on plate 11. Many of the same sites, showing stream diversions, are present on this plate as fish passage impediments.
Although irrigation diversion structures are responsible for dramatic, hydraulic disturbances in their immediate proximity, the most important effect is their physical obstruction to fish passage. Criteria for fish passage used for the reconnaissance study is presented in appendix C.
(5) Increased Sediment Input.
Stream systems that are geomorphologically balanced have a sinuosity, gradient, and channel geometry that allow transport of the quantity of sediment received. The sediment is the result of erosion of the catchment area and stream channel under a natural flow pattern. If for any reason the sediment transport capability is diminished, sediment will accumulate in the channel.
The most evident effects of sedimentation on fish habitat in the WWRB are as follows: (1) a reduced amount of pool habitat; (2) higher degree of cobble imbeddedness resulting in lower stream productivity and lower salmonid reproductive success; and (3) increased bank erosion and encroachment on riparian vegetation due to forced lateral channel adjustment.
Historically, the Walla Walla River supported significant runs of spring chinook salmon and summer steelhead. Fall chinook, chum, and coho salmon are believed to have been present in the Walla Walla River in smaller numbers (Chapman, 1981). Anadromous fish have spawned and reared throughout the middle and upper reaches of the Walla Walla River and its tributaries; although, the lower river was not historically used for spawning because of a lack of gravels and sluggish flows (Nielson, 1950).
Steelhead smolts are planted in the Touchet and Walla Walla Rivers. These steelhead are reared at the Lyons Ferry Hatchery on the Snake River and are placed in acclimation ponds on both the Touchet and Walla Walla Rivers prior to release. The decline of the anadromous fishery can be largely attributed to the irrigation diversions that dewater stretches of river and block or impede fish passage. The river system now supports a fair run of steelhead and some resident trout and char, most of which are redband (rainbow) and bull trout.
(1) Fish and Lamprey Eel Passage Impediments.
Diversion of stream flow for irrigation purposes has resulted in reduced flow in many areas of the WWRB, generally late June through October. This situation is most evident in the Walla Walla River in the Milton-Freewater, Orgeon, area where it is without-surface flow during much of the irrigation season. Plate 10 shows the location of irrigation diversions throughout the WWRB.
Impediments of fish passage may be by fish having to make repeated leaps to cross a structure, by fish being delayed by movement as they look for a passage around a structure, or a combination of both. The vast majority of the fish are impeded by irrigation diversions. Depending upon flow conditions in the river, the irrigation diversion structures may not be an impediment at all (under high flows) or there may be a barrier (low flows). No effort was made to differentiate impediments to different aquatic species. For example, steelhead have much greater leaping ability than resident trout. Therefore, what may be an obstacle to resident trout, may cause no delay for steelhead. Conversely, what may be an impediment for steelhead may not be a barrier for resident trout.
It should be noted that the fish passage impediments (see plate 11) will likely effect Pacific lamprey eels. The status of lamprey eels in the WWRB is currently unknown. However, the number is probably low reflecting the general decline of this species in the interior Columbia Basin.
Due to the annual spring/summer dewatering of the main stem Walla Walla River, the ODFW and CTUIR engage in a fish salvage operation just below the Milton-Freewater, Oregon, Nursery Bridge. The river is dewatered at Cemetery Bridge, approximately .4 km (1/4 mile) upstream from Nursery Bridge. The 1- to 2-day fish salvage operation rescues an average of 1,000 fish; the vast majority being rainbow trout and steelhead. Some 10 to 30 bull trout are also collected. Depending upon the time of the year the rescue operation occurs, the fish are either hauled to the mouth of the Walla Walla River or upstream to a section of the Walla Walla River that still has water. If the de-watering occurs in the May-June period, the majority of fish are steelhead smolts. These fish are taken to the mouth of the Walla Walla River. If the dewatering occurs in the June-July timeframe, the fish are transported upstream as they are mostly rainbow trout. Distinction between the fish can be based on size: Smolts being 12 to 18 centimeters (5 to 7 inches) in length and resident rainbow trout typically 5 to 10 centimeters (2 to 4 inches) in length.
The known distributions of steelhead and bull trout are restricted to the upper headwater areas of the WWRB (see plates 12 and 13). This is due to a number of problems within the basin relating to land use impacts such as logging, grazing, and road building. Temperature is largely considered to be the problem that restricts these fish to the upper basin. Steelhead and bull trout in the WWRB are both candidate species proposed for listing under the Endangered Species Act (ESA). Listing action could occur during 1998.
(2) Steelhead.
The status of steelhead is significant within the WWRB, as on the Oregon side of the WWRB no hatchery fish have been introduced. Since 1992, ODFW has maintained a fishtrap at the Nursery Bridge fish ladder in Milton-Freewater, Oregon. This allows them to count steelhead moving upstream through this reach of the river. They also gain additional information such as timing of the run, gender, size, and scale samples of the fish. As part of ODFW’s wild fish policy, all hatchery strays that enter the fish ladder are culled (killed) from the population.
Currently, there is only one place in the entire WWRB where actual definitive fish numbers can be tabulated, as shown below in table 4. This is at the fishtrap located at the Nursery Bridge fish ladder in Milton-Freewater, Oregon. The fishtrap was installed in 1992 so that ODFW could count the number of fish moving through the system. As can be seen below, the number of adult steelhead returning to this trap has continued to decline since the ODFW has been tracking these fish numbers.
| Table 4 - Adult Steelhead Count at Nursery Street Dam¹ | ||
|---|---|---|
| Years | Actual | Estimated Escapement² |
| 1992 to 1993 | 723 | 817 |
| 1993 to 1994 | 425 | 480 |
| 1994 to 1995 | 359 | 387 |
| 1995 to 1996 | 273 | 365 |
| 1996 to 1997 | 244 | (number not yet calculated) |
| ¹Numbers provided by ODFW. ²The 12 to 30 percent of the fish run that jump the dam and do not go through the trap. | ||
It is the policy of ODFW to cull all fin-clipped steelhead found in the trap (ODFW wild fish practice). These fish are typically from smolts released on the Washington side of the WWRB. Steelhead released on the Washington side of the basin are from a Snake River stock and are not native to the WWRB.
(3) Bull Trout.
The bull trout is a wide-ranging, typically non-anadromous species that inhabits most of the cold lakes, rivers, and streams throughout the western states and British Columbia. Within the WWRB, bull trout are found in the upper portion of the North and South Forks of the Walla Walla River, upper Touchet River, Mill Creek, and some of their tributaries. Bull trout require cold water, with 7° to 8° Celsius (C) [45° to 47° Fahrenheit (F)] appearing optimal and 15°C (59°F) maximum. Spawning occurs in cool water, below 9°C (48°F). Optimal incubating temperatures seem to be 2° to 4°C (36° to 39°F). Spawning occurs from August through November with eggs hatching in late winter or early spring. Emergence occurs in early spring through May, commonly following spring peak flows. Because of extended time in the substrate, bull trout are susceptible to mortality in unstable conditions. Successful reproduction requires channel and substrate stability and adequate winter waterflow to prevent the substrate from freezing. Bull trout require complex forms of in-stream cover. Adults use pools, large woody debris, large boulders, and undercut bank for resting and foraging. Juveniles also use side channels and smaller wood in the water. Channels for moving between safe wintering areas and summer foraging areas are also necessary.
One of the problems facing bull trout is the number of passage impediments and barriers in the WWRB. Bull trout may migrate many kilometers within a given basin during the winter when water temperatures drop to the point that allows them unrestricted access throughout the WWRB. Their population is fragmented because passage impediments and barriers prevent them from reaching many areas of the WWRB.
(4) Redband Trout.
The interior redband trout is a subspecies of the rainbow trout and is found throughout the WWRB. In the portions of streams and rivers that dry up or become too warm, these fish migrate to upper reaches. Diversion dams can prevent, or at least inhibit, this migration. Genetic diversity of this fish has been impoverished by land and water use practices and the stocking of nonnative rainbow trout (Behnke, 1992).
For a full description of the environmental resources in the WWRB, refer to appendix B of the Planning Aid Report, submitted to the Corps by the USFWS, Walla Walla River Basin Reconnaissance Study Planning Aid Report, January 1992. Also, refer to the attached Supplemental Planning Aid Report, Walla Walla River Basin Reconnaissance Study, December 1996 (see appendix B).
Vegetation in the headwaters of the drainage is primarily evergreen forest dominated by douglas and grand fir in the higher elevations and becoming a more open forest dominated by ponderosa pine at the lower elevations. Differences between northern and southern slope vegetation, as reflected by the proportion of grassland/steppe communities, increases in direct correlation with a decrease in elevation and coincidental lower precipitation. A unique riparian community dominated by cottonwood, white alder, willow, and various shrubs occurs throughout the basin.
Different stages and intensities of logging and grazing have impacted the upper basin vegetation to varying degrees. Irrigated and dryland agriculture and animal grazing have impacted the lowland riparian community to some degree as the woody vegetation has been seriously degraded, reduced, or totally eliminated throughout most of the WWRB. These activities have also negatively impacted the native shrub-steppe community. Years of over-grazing and increased fire occurrence have eliminated much of the native sagebrush and bunchgrasses. They have been replaced with lesser quality rabbitbrush, cheatgrass, yellow star thistle, and other undesirable grass and broadleaf weeds.
Wildlife habitat quality and characteristics vary greatly in the WWRB. Wildlife habitat ranges from good to pristine in the upper reaches of the Walla Walla River, Mill Creek, and the Touchet River. Good numbers of large mammals are present (i.e., elk, white-tailed deer, black bear, coyote, bobcat, and mountain lion). Furbearers are common (i.e., beaver, otter, and raccoons). There have been 277 bird species recorded in Walla Walla County (Blue Mountain Audubon Society, 1988).
At lower elevations, riparian and upland habitats have given way to intensive agriculture, with the concurrent elimination of many of the wildlife species that once occurred (Mudd, 1975). Remnant riparian zones usually provide the only remaining significant wildlife habitat. Only 37 percent of the Touchet River riparian zone remains in natural riparian vegetation (Mudd, 1975). On inventoried streams in the WWRB in Oregon, 70 percent of the riparian zone is classified as being in poor condition (Water Resources Commission, 1988). Those wildlife species that persist must be tolerant of disturbed and fragmented habitats and be able to utilize adjacent agricultural lands. Wildlife species found at lower elevations include white-tailed and mule deer, ring-necked pheasant, California quail, mourning doves, variety of song birds, and small mammals.
The largest expanse of relatively high-quality riparian habitat exists on the 600 hectare (1,500 acre) Corps managed Wallula Habitat Management Unit, located at the mouth of the Walla Walla River. This tract of land offers a mixture of cottonwood forest, wetlands, sagebrush, and agricultural lands utilized by dozens of species of waterfowl, shorebirds and songbirds, raptors, upland game birds, mule and white-tailed deer, furbearers, and small mammals.
c. Neotropical Migratory Birds.
Neotropical migratory birds (NTMB) have experienced large population declines due to habitat destruction on the breeding and wintering grounds and along migration routes. These are species which breed in the United States and Canada and then fly south to Mexico, Central or South America, or the Caribbean.
In Washington, there are 118 NTMB with all but 7 having been recorded in the WWRB. Those found in the WWRB (both in Washington and Oregon) are listed in appendix B. Of the total species known to occur in the WWRB, 15 species are known to have experienced long-term declines within Washington.
Eight of the NTMB species with declining trends depend on riparian habitats, which helps illustrate the value of this important habitat type. In addition, 57 percent of the NTMB in Washington are associated with riparian habitats.
A list of problem and opportunity statements was developed initially by the study team in the Walla Walla District. This list was distributed to potential sponsors in the WWRB (listed in section 6.0), and their feedback was solicited. After receiving their feedback, the list was then modified to the current form seen below. The following listing is in no particular order or ranking.
The following list was meant to be all-inclusive of the types of water-related problems present in the various areas of the WWRB. Therefore, problems outside the purview of the Corps were included (i.e., non-point source pollution).
3.01 Upper Touchet Basin Above Dayton, Washington
3.02 City of Dayton, Washington
3.03 City of Waitsburg, Washington
3.04 Touchet Valley, Washington (Areas between Waitsburg-Dayton and Waitsburg-Mouth of Touchet River
3.06 Upper Walla Walla River Basin (Main Stem Walla Walla River Upstream of Milton-Freewater, Oregon
3.07 Lower Walla Walla Valley and Tributaries (Main Stem Walla Walla River Downstream of Milton-Freewater, Oregon, to the Mouth, Pine Creek and other Tributaries)
3.08 City of Milton-Freewater, Oregon
3.09 City of Walla Walla, Washington
3.10 Environmental (Entire WWRB)
b. Opportunities
Potential project alternatives were explored in the WWRB in the following areas: The upper Touchet Basin, Washington (from the town of Prescott upstream); main stem Walla Walla River, Washington; salmon reintroduction (basin wide); and certain flood damage reduction alternatives. As stated in the introduction, the primary scope of these investigations was to see what improvements could be made for fish and wildlife resources in the WWRB.
This list of areas with potential project alternatives was developed by attempting to determine which localities in the WWRB had a strong interest in having a Corps cost-shared project in their area. Unless strong interest was shown by local government, further exploration by the Walla Walla District was suspended.
Development of alternatives was limited to these areas as they were the geographical locations that expressed a strong interest in taking the Corps efforts to a feasibility phase analysis.
None of these potential project alternatives should be considered firm or final. All of these alternatives may be changed, supplemented, or eliminated by additional issues that may arise (e.g., landowner concerns). The potential project alternatives listed below may be studied in the feasibility phase or may not be studied at all. Variations of the alternatives may be explored or completely new alternatives may be developed and analyzed.
4.01 Environmental Restoration
a. Upper Touchet Basin, Washington (From the Town of Prescott Upstream)
(1) Introduction
A setback levee concept was explored for the upper reach of the Touchet River. Two alternatives were examined with different designs. Both of these alternatives would entail some type of riparian easement that would provide for environmental benefits. The following is a discussion of how those environmental benefits would be realized.
Setback levees are an effective means of restoring a higher degree of riparian function and channel equilibrium and thus benefiting aquatic habitat quality while providing flood protection. The degree to which channel function is restored is largely a function of the size of the engineered floodplain. The floodplain is determined by the distance the levees are set back from the channel and the degree to which the channel is allowed to adjust within that floodplain. The degree to which riparian function is restored is generally a matter of how vegetation is managed within the engineered floodplain. To maximize aquatic habitat benefits within the engineered floodplain, the stream is allowed to flood, native riparian vegetation is allowed to colonize, and the channel is allowed to adjust laterally.
Benefits to aquatic habitat quality that can be expected from replacing existing levees with setback levees are as follows: (1) increased shade and lowered water temperatures; (2) increased recruitment of large, woody debris; (3) increased stability of streambanks; (4) increased cover from large, woody debris, undercut banks, and surface turbulence; (5) increased amount of pool habitat; (6) increased in-stream habitat diversity; (7) increased channel stability; and (8) higher water table with increased capacity for interstitial flow through channel substrate particles for juvenile fish and macroinvertabrates.
A significant part of a watershed is the riparian area associated with a stream or other body of water. Although riparian areas are typically 1 to 2 percent of the total land area, they contain a disproportionately high percentage of wildlife habitat and recreation areas. Riparian areas are the transition between the aquatic ecosystem and the nearby, upland terrestrial ecosystem.
Because riparian ecosystems are relatively small areas and occur in conjunction with waterways, they are vulnerable to severe alteration. Nationally, these ecosystems have been heavily impacted by road, bridge, and pipeline construction; water developments; flood control channel modifications; industrial and residential development; agriculture; irrigation; livestock grazing; mining; and accidental habitat loss.
The inherent values of riparian zones in their natural state are as follows:
Flood damages in a watershed with deteriorated riparian and upland areas may be immense because of large amounts of transported sediment and sometimes the swift changes in channel configurations. However, on streams with sufficient diversity and cover of riparian vegetation, bank building through the deposition of sediment occurs during high flows. Generally, mature plants with strong root systems are required to hold streams and riparian zones together. The stems from these plants provide roughness and resistance to flow. At high flows, these species bend but do not break, and they are extremely effective at trapping sediment transported by the stream. With continued sediment deposition and bank building, particularly along low gradient channels, water tables rise and ultimately may reach the root zone of plants on former terraces or floodplains.
Healthy riparian areas demonstrate stable banks with adequate shading, an elevated saturated zone with increased subsurface water storage, increased summer streamflow, cooler water in summer, improved habitat for native fish and other aquatic organisms, high forage production and quality, and high diversity of wildlife habitat.
(2) Assessment.
The health of a riparian ecosystem can be determined by identifying the stream channel morphology: (1) The level of water storage in the streambanks, (2) the plant communities present, and (3) the extent of adjacent land uses. A stream allowed to follow its own course throughout the floodplain, depositing sediments and saturating the ground, will stimulate plant generation. The natural community of plants will, with time, begin to stabilize the ground, especially the banks adjacent to the stream. The plants provide a level of protection to the floodplain necessary to withstand the damage that can be caused from periodic erosive flood waters. Without this protection, the stream channel will begin to degrade, allowing for bank erosion and the subsequent inability of the floodplain to support the diversity of vegetation needed to stabilize the soil and streambanks. Subsequent high-water events will allow the intense energy of the water to pickup and carry soils all along the system, depositing them where it is least desirable (impingement points along the stream), and creating more problems downstream for the stream channel.
(3) Existing Condition.
The Touchet River from Prescott to Waitsburg and from Waitsburg to Dayton displays signs of a not-so-healthy riparian ecosystem. The influences of adjacent land uses have led to an ecosystem that was not able to protect itself, or those who use the land, during this past winter’s flood event. Agriculture (primarily), with some grazing, and increasing residential development have caused the Touchet River riparian zone to be very narrow and non-continuous all along its length. The vegetation noted is largely cottonwood at a very mature stage with some regeneration that is located immediately within the existing stand of trees. The width of the riparian zone consists largely of one row of cottonwoods for most of its length, with some exceptions where the width grows to as much as 30 meters (100 feet). Agriculture activities tend to encroach upon the stream limiting the width of the riparian vegetation. Below Waitsburg, the stream channel is more degraded than above Waitsburg. This down cutting of the channel makes it more difficult for vegetation to get a good start because the water table is lower in the surrounding lands. Above Waitsburg, land uses change to more residential development along the river. Here the channel is not as degraded. Although the width of the riparian zone is still limited, marginal streambank storage of water is present to support a reduced riparian habitat. Ad hoc levees have been built in many reaches of the river.
(4) Benefits.
The benefits gained are the number of hectares of riparian habitat that would be created by allowing nature to take over the floodplain. An ancillary benefit to the project would be protection to human life and property in the case of floods up to a 100-year event. Once the hectares are determined, the benefits can be described in terms of aquatic habitat improvements, NTMB usage, biomass production, filtration of sediments, and possibly improvements to rotation grazing, if desirable.
In general, it should be possible to build low dams across the Touchet River floodplain to store flood flows (much like a series of very low dams). For clarity, this will be referred to as the "cell" concept, each cell being an area where water would be ponded by the cell's rectangular shape. Ten-foot-high cells were designed, set at regular distances (to minimize the number of existing buildings damaged), and located between the highway and the mountains. See plates 25 and 26 in appendix A for an outline of general configurations of the cells.
This alternative, to capture flood flows and release the water at a time when the Touchet River would be able to pass the flows more efficiently, involves the building of low dams across the Touchet River floodplain. This would require some type of weir structure in the river itself. As long as the proposed weir structure effectively allows for fish passage and no degradation of the river channel, then impacts would be minimal (see appendix D, page D-3).
By allowing water to annually flow overbank (if the flows were high enough) depositing sediment on land and in the channel, the streambanks would begin to become saturated with water. This would encourage the growth of riparian vegetation. In addition, there would need to be restrictions on acceptable land uses in the floodplain. Primarily, a 60-meter (192-feet) riparian zone (on one side only or both sides total) would need to be allowed to develop, which means there would be less ground in the floodplain left for agriculture. Repeated overbank flows would encourage vegetation development, allow the banks and shoreline to become more stable, and allow for the raising of the surrounding water table. As vegetation succession progresses, the plant diversity would greatly increase. Channel characteristics would also change. Wide, shallow channels with either flattened banks or steep, eroding, and undercut banks would be replaced by more narrow, deeper, and more stable channels with well-vegetated banks.
By allowing for flood-flow storage in the floodplain, flood damages can be reduced. By allowing for a healthy riparian zone development in association with the floodplain storage, nature can be used to assist in the protection of residential, commercial, and agricultural properties.
An arrangement of 37 cells were laid out. Each cell begins adjacent to the highway or railroad, runs down the valley until it reaches approximately 3 meters (10 feet) in height. The arrangement then turns and runs across the valley, crosses the river, and runs to high ground against the mountains. At each point where the cell would cross the river, a structure would be put in place that would actually force water out of the channel and pond it in the adjacent cells. The river crossing is assumed to be made of a hardened weir of undetermined proportions. The structures were laid out on even 3-meter (10-foot) contours as often as possible; but, where space permitted, a few of the dikes were allowed to be higher than 3 meters (10 feet). Alignments were worked around existing structures, as much as possible.
The total storage upstream of Waitsburg was relatively small (compared to downstream Waitsburg) because of the narrowness of the floodplain on the far side of the river (see table 5). The small amount gained by extending the pool to the valley walls was offset by the need to work around existing structures. However, there was not a tremendous amount of water stored in either of these scenarios. The cost of this alternative is $39.9 million.
This alternative would also require large amounts of land to be set aside by landowners through flood easements and the footprint of the actual project. For this reason alone, this alternative does not have much promise.
c. Touchet River Setback Levee.
The other variation of a setback levee through the reach of Prescott to Dayton would be a much more straight-forward concept. This would require the levee to be built back from the channel a distance of 125 meters (410 feet) from each bank. Within the levees, a riparian buffer strip of 60 meters (192 feet) from each bank would be in place. (See plate 14 for the location of where this reach on the Touchet River is located and appendix D, page D-1.)
By taking advantage of local topography, it would not be necessary to build a continuous levee system throughout the entire reach of the valley using the valley wall on one side. Also, if Highway 12 or the railroad (in the reach between Dayton and Waitsburg) were found to be closer than 125 meters (400 feet) to the river bank, the levee could be built next to the transportation corridor and avoid the cost of moving either the highway or the railroad. No new building of any structure would be allowed to take place within the levees. This would allow for the maximum amount of room for water to be stored within the channel.
The riparian zone purchased from the landowners could be used to prevent any degradation of the riparian area. This could either be in the form of an easement or fee purchase. This would prevent heavy equipment from entering the channel. The easement could also be of the floating type; meaning, as the river cut a new channel, the project area would move with it. This would provide numerous environmental benefits as stated in the section 4.01a.(4) above.
Between the riparian easement and the setback levee [a distance of 60 meters (200 feet)], under this conceptual alternative, the area could be used by the landowners as they desire, as long as it was kept in "open space." Depending upon further information gathered in a feasibility phase study, it may be desirable to expand or contract the proposed levee alignments from the river channel and the width of the riparian buffer strip. For example, the Walla Walla District is in the process of gathering aerial photos taken of the Touchet River in the 1930's. Should these become available, this may be a desired condition for river meander width across the valley.
The river would be contained within this setback levee where it would not be allowed to move out of this channel between the levees. This in turn, may provide an incentive for landowners along the river to participate in this project. Homes, barns, and other buildings would be inside the levee, if built as stated above. There are a number of options on how to resolve the issue of buildings between a stream and a levee. Such buildings could be relocated outside of the levee system, elevated so floods would not cause damage to the structures, or it may be possible to modify the location of the levee so that the building would not be between the levee and the river.
The cost of this alternative would be $47.5 million. However, it should be pointed out that the cost may be significantly less. Existing rip-rap that is in place along the river could be removed from the riverbanks and used in the construction of the setback levee. Using local topography to a greater extent may reduce the need to build setback levees in the areas currently projected.
(1) Levee Setback within Waitsburg.
Within the city of Waitsburg, a proposed buyout of 17 properties is scheduled under a Federal Emergency Management Agency (FEMA) sponsored program. An alternative has been developed for the section of the Touchet River through Waitsburg. The alternative has assumed the FEMA buyout would be completed, and it would be possible to move the levees that are now present in town away from the river.
There would be no real estate costs involved for this alternative as all the necessary rights would have been purchased under the FEMA buyout. Realignment of the levee would cause the structure to be set back from the river, giving more cross sectional area that would allow more room for floodwaters. As this area within the channel revegetates, channel morphology will improve (i.e., by increasing the pool:riffle ratio). This will also provide for more shade and input of vegetation into the river. Opening up the channel at this point will reduce peak flows downstream from the town of Waitsburg.
The cost of this alternative would be $6.2 million. Much of this cost is represented by the replacement of two bridges in town (over $3.5 million of the total cost). For comparison purposes, a brief examination was made of the possibility of raising the levees that are currently in place through the town of Waitsburg. Such an alternative could be expected to cost $16 million. This option would not only cost more but would not provide any improvement to the environment. This alternative was not studied in any further detail.
(2) Coppei Creek.
It may also be viable to construct setback levees along Coppei Creek upstream from the city of Waitsburg, similar to the levee setback within Waitsburg. This would be done with a levee constructed to protect just the south end of the town. However, this option was not explored in any detail by the Walla Walla District for the purpose of environmental restoration. There would be similar environmental benefits and costs as compared to the Touchet River setback levee except that they would be on a smaller scale. However, a similar alternative for Coppei Creek was examined in section 4.02, Flood Damage Reduction.
(3) House Relocation in Dayton.
Early in this study, five properties were identified on the main stem Touchet River that suffered heavy damages from the February 1996 flood (just downstream from the confluence with Patit Creek). Homeowners, at that time, had expressed an interest in being bought out and relocated out of the floodplain (see appendix D, page D-5).
This alternative would involve the purchase of five homes and relocation of the levee within the town of Dayton.
The benefits for such a project would be similar to what would be experienced in the Waitsburg buyout (e.g., increased channel capacity, etc.), except on a smaller scale. The estimated cost of this project is $935,000.
However, it should be pointed out that the levee that failed to protect these homeowners during the last flood has been rebuilt. Because of this action, these homeowners may now feel they are sufficiently protected and may not be interested in this alternative. Further discussion with the property owners and the city of Dayton is necessary before providing any recommendations.
d. Stream Restoration - Main Stem Walla Walla River.
The Washington Department of Fish and Wildlife (WDFW) owns a small amount of land along the main stem Walla Walla River (see plate 15) where the previous owners of the property had built a system of ad hoc levees. The three sites are identified as the "Swegele, McCaw, and DeMotts" properties. This option would examine removing these levees to provide more benefits for fish and wildlife. There is room, with contingencies, for these levees to be removed without harming any third parties (see appendix D, page D-7).
(a) Swegele.
The approximately 48-hectare (119-acres) Swegele property is located both up and downstream of Whitman Mission Road, just south of the Whitman Mission National Historical Site. On the downstream portion of the property, there is a discontinuous levee that was built by placing large rock along the left (south) bank of the main stem Walla Walla River. This rock is placed in a reach approximately 1/2 km (1/3 mile) in length.
At this site, rock would be removed from the streambank using a backhoe with a "thumb" and then stockpiled in the WDFW parking area along Whitman Mission Road. The rip-rap could then be used by the WDFW in future bio-engineering projects they may wish to undertake.
Due to the small size of this site, it may be desirable to let natural colonization of riparian plants take place. This would also help to reduce costs.
Should the channel move south, where the heavy rock may have been keeping flows from migrating, increased erosion may occur over a short timeframe. However, long-term environmental benefits from removing the rock will outweigh any short-term costs from increased erosion.
Should the channel migrate to the south, there is room for the river to do so as the WDFW owns a large amount property on this bank (back to Stoval Road). The construction cost for this site would be $9,000.
(b) McCaw.
This 40-hectare (99-acre) property is located along the McDonald Bridge Road, upstream from McDonald Bridge. On the south bank of the river, 275 meters (300 yards) upstream from the bridge, there is a hardened surface parallel to the river. It may have been used by the previous landowners as a levee or a road surface to gain access into the further reaches of the property.
This hardened surface could be left in the floodplain and would be loosened with a bulldozer equipped with ripper teeth. This would reduce the ground compaction that is present in the site reach. As the hardened surface material was spread out, it would allow water to reach behind this area, thereby, improving the riparian zone. Reducing ground compaction, which would also be complete after a few freeze/thaw events, would allow for the soil to absorb water more readily and improve conditions for vegetation growth.
Native vegetation would then be placed back along the streambanks where soil had been disturbed under the rock removal. Species such as willow (Salix spp.), red osier dogwood (Cornus stolonifera), black cottonwood (Populus trichocarpa), and black hawthorn (Crataegus douglasii) would be planted in the disturbed areas, along with other native vegetation.
The construction cost for this site is $13,000.
(c) DeMotts.
This 9-hectare (23-acre) property is located along the McDonald Bridge Road, downstream from McDonald Bridge. There is a continuous levee running along the left bank of the Walla Walla River for approximately 1 km (1/2 mile), where the DeMotts property line ends. The levee then continues further downstream along adjacent private property. The distance from the levee to the property boundary provides a corridor of approximately 60 meters (192 feet).
The alternative, here, would remove the levee and the material from the riparian area. The material would then be placed along the property boundary. Setting the material here would, in essence, mean moving the levee from where it is now to a parallel position further back from the river; a setback levee. Setting the levee back to this spot is to insure, if the channel did migrate south and erode, it would be stopped before it gained access to the adjoining private property.
As stated in the McCaw portion above, the disturbed areas would be revegetated with the species noted.
Additional provisions may be necessary for the irrigation diversion that is in place 100 meters (328 feet) downstream from the McDonald Bridge. This irrigation diversion is on the right bank where a "push-up" dam is annually built to allow for water to be forced down this irrigation channel. There is a possibility that the river, with the expanded room given by removal of the levee in the floodplain, may move to the left (south). This could, potentially, make it more difficult to gain irrigation water from the river.
Construction costs for this piece of levee removal would be $201,000. This cost is significantly higher than the previous two sites due to the need for rebuilding the levee along the south end of the property line.
(2) Environmental Benefits.
The environmental benefits that would be gained in these three areas would be largely similar. By reducing the heavy rock placement along the river, the channel will be able to assume a more natural stream morphology. Instead of a uniform channel along the river, where the depth of the river bottom is largely uniform, variations in the channel would be able to take place. This could be caused by such natural events as trees in the river forcing water to scour underneath the tree and dig a pool. Scouring deep holes in the riverbed will provide holding cover for adult steelhead migrating upstream to spawn. These same benefits for adult steelhead would also improve habitat for adult spring chinook salmon, if they are reintroduced into the WWRB.
Many of the same benefits identified in section 4.01 for setback levees on the upper Touchet River would also be applicable to levee removal on these three properties.
Shade and input of vegetative matter will be improved by the riparian vegetation that will grow where the heavy rock was once in place. Reduction of rock along the river will also reduce water temperatures, as there will not be a hard material in place to absorb heat.
Removal of levees creates more overbank flowage areas during large flows and may modify the hydrograph downstream.
Costs for all three of the sites would total $229,000.
(1) Planning Objectives.
While the WWRB provides habitat for numerous fish species, the focus of this potential project alternative for environment restoration is chinook salmon that have been absent from the drainage since the early part of this century. If a population of chinook salmon is reintroduced to the WWRB, it is assumed it would not be subject to the ESA and no critical habitat would be designated. The ESA would not be applicable here as the native stock of salmon for the WWRB has been completely eliminated.
Restoration of salmon in the WWRB will require a comprehensive effort that has four facets: Stream/watershed habitat enhancement; passage improvements (ladders and screens); hatcheries; and in-stream flow enhancement. For purposes of this reconnaissance report, the Walla Walla District has focused on the issue of in-stream flow enhancement. There is a potential for the Corps to become involved in areas relating to habitat enhancement (i.e., what would be contemplated under the Touchet setback levee described above) and passage improvements (e.g., the new fish ladder at Nursery Bridge that is already in the planning stages).
The following objectives could be used for the area of in-stream flow enhancement:
There are three runs of chinook salmon in the Columbia River that are recognized by their time of entry, time of spawning, age, and time of smolt migration. The stock that historically occurred in the WWRB drainage was the spring chinook that enters the Columbia River between February and May and spawns during the period July through December. Juvenile spring chinook salmon rear for one year in natal streams and out-migrate downstream as yearlings with peak out-migration occurring in May.
For purposes of this report, it is assumed that the Carson Hatchery (located near Bonneville Dam on the Washington side of the Columbia River) stock would be the genetic source for chinook salmon reintroduced to the WWRB. Table 6 shows the precise timing of each freshwater life history stage of the Carson Hatchery stock. It is believed that if spring chinook salmon were reintroduced to the WWRB, most spawning and rearing would occur in high-elevation tributaries and juvenile chinook salmon would out-migrate as yearlings.
All life stages of chinook salmon have specific habitat requirements. In general, adult salmon require conditions allowing them to traverse the entire length of the Walla Walla and Touchet Rivers and then hold for a period of time before spawning.
The critical time period for upstream passage of the adult Carson Hatchery stock chinook salmon is April through June. During this "adult passage window," very specific hydrologic and physical conditions must be present to accommodate passage of migrating adults. The sex, size, and physical condition of the fish attempting passage, including past injuries and sexual maturity, can effect the capability of migrating adult fish. Restoration of flow through water conservation, possible decreases in irrigation withdrawals, enhanced aquifer storage, or flow augmentation would have a very positive effect on the fish habitat quality in the Walla Walla River drainage.
The primary issue and obvious initial phase for restoration of a self-sustaining salmon fishery is adult passage to high-quality spawning habitat, which is the emphasis of this reconnaissance study. It is our assessment that if NMFS criteria are met for chinook salmon passage, it will also provide passage for steelhead, pacific lamprey, and bull trout. The chinook salmon passage criteria that is currently being used in this study is provided in appendix C. If measures are taken to restore flow levels to meet this passage criteria during the migration period (balanced with juvenile outmigration flow criteria), it is believed that the percent of Carson Hatchery stock smolts returning as adults could resemble that experienced in the Umatilla River where a similar flow restoration project is currently underway.
During the adult chinook salmon passage window, it is also essential that specific water quality conditions exist. In the WWRB, water temperature may become a limiting factor near the end of the adult chinook salmon passage window. However, the purpose of this potential project alternative is not just to provide flows for a passage corridor, but rather to restore in-stream flows to the mouth of the river throughout the dewatered season. From a biological standpoint, it is important to provide stream flows year-round, if possible.
Spawning occurs in headwater tributaries in late summer and early fall with the peak in the August though September time period. Survival from egg through emergence is perhaps most effected by waste removal and oxygen supply to the eggs, embryos, and sac fry that require reasonably clean gravel and, thus, adequate intergravel flow. Upon emergence, which occurs in February though March, fry utilize in-stream cover to avoid predators (e.g., cobble interstitial spaces). As they increase in size, the chinook salmon gradually move into different habitat types and utilize a variety of food items and cover types. During rearing, juveniles prefer large, deep, low velocity pools with abundant cover. The availability of quality pool habitat is often a limiting factor for this life stage. The rates of primary and secondary production largely determine the amount of food available to fish. Also, fish abundance in streams has been correlated with the abundance and quality of cover.
The seaward migration of juvenile chinook salmon begins in the spring when water flows are high. It is assumed that conditions in the WWRB will generally be favorable for the downstream migration during the period April through May.
Specific requirements for habitat attributes effecting all life stages of chinook salmon are detailed in appendix C.
It should be noted that there will be concerns by many business and agricultural interests in the WWRB as to what the economic impact of salmon in the WWRB may mean. While it is impossible to state exactly what this cost (if any) would be today, it should be pointed out that this same question arose in the Umatilla Basin when the CTUIR proposed to reintroduce salmon in that basin. This would be examined thoroughly in the feasibility phase.
The CTUIR in the Umatilla Basin, who are likely to be the sponsor for salmon reintroduction, has taken a cooperative approach with landowners, irrigators, and business interests. It should be pointed out that no entity or individual lost a water right or had any "takings" of property rights in the Umatilla Basin during the process of salmon reintroduction.
An assumption attending all of the alternatives that will provide more water for in-stream flows is that legal guaranties will be made to ensure that additional water will be left in the stream and not expropriated by irrigation users downstream. Any additional water provided would be left in the stream as dedicated in-stream flow. The Corps’ role is to provide in-stream water flows, working with other entities in the WWRB along with private landowners.
Also, state water right issues would have to be considered in a feasibility phase analysis of these alternatives, where applicable. These issues may add or detract to the viability of the options stated below. At this reconnaissance phase, the water right issues are assumed not to preclude any of the following options from being pursued.
The following is a discussion of the possible in-stream flow enhancement options that could be implemented as part of a comprehensive solution to reintroduce salmon into the WWRB.
(2) Groundwater Pumping and Water Injection.
An option that was briefly examined by the Walla Walla District was the conceptual idea of taking high winter flows and diverting them so they could be pumped into the groundwater table. This water would then be stored below the surface where it could later be added to in-stream flow to create the necessary water for salmon reintroduction.
After an initial examination, this option was dropped from further consideration. This was due to the concerns about the current state of groundwater depletion in the area and the issue of water quality.
Currently, groundwater in the WWRB is being "mined," and the water table is being lowered over time. Creating a project that would tie into these underground water sources would likely lead to litigation on determining the amounts of water used to provide for salmon flows. This could be the case if a private irrigator felt he/she was being injured by the government’s action.
Water quality would be a concern, because it is currently unknown what changes in water quality may take place if surface water was stored in the aquifer for any period of time.
Because of these uncertainties, this option was dropped at an early stage and not examined any further.
(3) Upstream Storage.
There is the possibility of looking at upstream storage in the upper WWRB. This would mean examining the possibility of building dams on the tributary streams. These dams would have the purpose of storing water from high winter flows and allowing releases later in the year to augment in-stream flows. Plate 16 shows the locations of these possible sites. (See appendix D, pages D-9 through 12).
Table 7 indicates the costs for these storage sites.
Environmentally, there would also be problems with building of large storage structures in the upper parts of the WWRB. These places are largely the last good habitat that is available to native cold water fish species, namely bull trout and steelhead. Bull trout are expected to be listed in 1998 under the ESA. The genetics of the WWRB steelhead need to be resolved before they are listed as a threatened species under the ESA. This action could occur by early 1998. Both species would suffer a severe negative impact by the building of a dam.
The purpose of building upstream storage facilities would be for environmental restoration (i.e., chinook salmon). However, this would cause a "trade-off" to be made: A gain in chinook salmon population would be at a loss of bull trout and steelhead populations. It is unlikely that ODFW, WDFW, and CTUIR, who are the co-managers of fishery resources, would be willing to make such a trade-off. The native steelhead and bull trout are an invaluable genetic resource that are irreplaceable.
(4) Small Storage Sites.
Off-stream storage was explored as an option, as was smaller on-stream storage sites. Use of off-stream storage should preclude impacts to existing steelhead and bull trout populations, as they would be in locations where there are no rearing populations.
Off-stream storage sites generally cost much more than a traditional storage (on-stream) site. This is because a water delivery system has to be constructed to get water to the facility. The possible small storage sites are shown on plate 16.
The off-stream storage sites are typically much smaller in their ability to store water than on-stream storage sites. The canyons they are located in are a smaller size and do not have a great amount of room to store water.
It should be noted that none of these upstream storage sites were explored in enough detail to see what issues would be involved with actually moving the water to these storage basins, if they were ever built. It may be possible to gravity feed these storage basins, but it also may be necessary to pump the water to these sites. This piece is another component that would also increase the cost of this option (see plate 16).
The upstream storage sites identified and the streams that would have peak flows diverted are presented in table 8. Extended benefits for the water have also been identified. There are other likely sites that warrant further investigation that were not uncovered during this reconnaissance phase.
(a) Site Descriptions.
The following information was gathered using visual analysis and other existing information obtained from maps and documents. The route to get water from the effected river or stream to the off-stream sites has not been identified. Therefore, the routes were not evaluated in this reconnaissance study.
1. Whiskey Spring.
This site is 100 percent on U.S. Forest Service (USFS) land and managed under the Umatilla National Forest. In reviewing Umatilla National Forest maps, the Tollgate site is being managed for wildlife and riparian habitat. Looking at the U.S. Geological Survey (USGS) topographic maps, there does not appear to be any type of stream at this site. The riparian area is likely a low spot where water gathers up to some elevational gradient and then runs off when the elevation is exceeded. Soil moisture saturation allows for riparian vegetation and, therefore, the riparian condition.
2. McDougall Camp.
This site is largely privately owned with a small portion of the southern end of the proposed impoundment area located on the USFS lands. There are a number of cabins either within the area to be impounded or at the perimeter. It appears only one cabin would be flooded as well as the power line supporting the cabin. In addition, there is a stock corral used for penning up cattle during transport operations. Coyote Creek runs through the middle of the site. The creek is very small in size, as noted by the ability of an average-sized person to be able to step across it. A second tributary was found within the impoundment site that is not noted on the USGS map. The surrounding area consists of an open meadow with portions of it quite water saturated and supporting obligatory wetland plants. The meadow transitions into coniferous cover as the elevation increases to the upper limits of the proposed ponding. The habitat is there to support fish since there are food sources. A great deal of bird activity is present in the area.
3. Cash Hollow.
This site is privately owned. The creek has deeply cut banks at the upstream end with a rather steep gradient. The riparian band is about 15 meters (49 feet) wide. There are mostly locust trees at the upstream end of the proposed ponding site; transitioning to sumac, cottonwood, willow, elderberry, alder, and rose as the canyon opens up more and as the creek channel narrows. Below the siting of the dam, as the elevation becomes less steep, large cottonwood and alder dominate the riparian zone. There are no vertical structures in the ponding area, just remnants of old structures. There is a dirt road, known as Joe West Bridge Road, paralleling a portion of the creek up to the top of the ridge. The side canyons abutting the riparian area appear heavily grazed. Fish habitat is questionable; however, wildlife habitat is good in the riparian zone.
4. South Fork Walla Walla River.
This site is partially on Bureau of Land Management (BLM) lands and partially on private lands. The site was not visited since a BLM gate blocked vehicle access to the proposed site.
The following assessment is made for the entire proposed project site based on descriptions from the South Fork of the Walla Walla River, Area of Critical Environmental Concern, Environmental Assessment (Bureau of Land Management, 1992). The BLM has designated that portion of the South Fork Walla Walla River that falls under its jurisdiction for management as an Area of Environmental Concern. Its scenic value is given the highest rating category BLM uses based on the high vertical relief in the prominent cliffs, the variety of vegetative types, the clean cascading water, and rich color combinations. Bull trout, a candidate species for listing under the ESA, are abundant. The stream currently has a steelhead run that is also a candidate species for listing under the ESA. The riparian habitat consists of three separate, but interrelated, plant communities. The sheer rock faces and outcroppings, along with their seeps and springs, create a moist micro-climate for mosses and ferns. The springs create bogs and marshy areas along the toe of the slopes providing habitat for sedges, rushes, and grasses. Along the edges of the river, a highly diverse and well-developed shrub and tree community exists. Species found along the river are ponderosa pine, douglas fir, grand fir, white fir, alder, willow, paper birch, water birch, pacific yew, black cottonwood, mock orange, ninebark, serviceberry, western mugwort, red osier dogwood, elderberry, and snowberry. Western paper birch has not been previously reported in Oregon, although it is found in southeastern Washington. Therefore, the birch is of regional importance due to its uniqueness.
The BLM recognizes the relevance and importance of the fisheries, wildlife, riparian, and scenic values within the area. They have determined the area needs to be protected and managed for the identified values because the area is heavily used by recreationists. This use has resulted in sustained severe impacts to the riparian areas and hillsides.
5. Scott Canyon and Keseberg Canyon.
These two sites are located adjacent to each other. Both canyons are privately owned. Observations from a distance, identified Scott Canyon to be largely grass vegetation with no or limited woody vegetation. There appeared to be no streams running through the canyon. The area above the canyon appeared to be farmed and the side slopes be managed for cattle grazing. Keseberg Canyon appeared to be similar in values to Scott Canyon (see appendix D, page D-15 and D-16).
6. Pine Creek/Dry Hollow.
The Pine Creek/Dry Hollow site is privately owned and totally surrounded by agricultural fields and cattle grazing pastures. This portion of the creek, observed beginning about 2.75 km (1 1/2 miles) below the proposed dam, is well vegetated for the most part. There are areas where fields crowd the creek bank; therefore, breaking the riparian corridor. There is good growth of trees with adequate understory along the creek where it is allowed by neighboring farming practices. The area above the proposed ponding site is all cultivated farmland that likely extends down along the side slopes as far as slope steepness will allow. It appeared that the storage facility would not impact much of the stream.
7. Blue Creek.
The proposed water storage site is along Blue Creek. It is private land with a road that follows the creek to its origin. The creek bottom is largely rock with little gravel or silt materials. This is supported by the fact that there is a quarry operation adjacent to this downstream view point. There is good riparian habitat along both sides of Blue Creek. The channel is deeply cut. The north and east facing slopes are well vegetated with conifers. The west facing slope is populated by grass and rock outcroppings. The creek appears healthy and vibrant; however, it is not very wide. Potential fishery is unknown. Trout and steelhead are present.
8. Russell.
The site is privately owned and almost entirely agricultural fields. The proposed storage site does not have a water course. The Lower Waitsburg Road would need to be relocated. It appears one house and some outbuildings might be impacted. There is a large grove of mature trees that would be impacted.
9. Whiskey Creek.
There is a small creek running through the site. If riparian vegetation were present, it was totally removed during a recent flood event. The bottom of the stream is rock, limited gravel, and silt materials. The placement of the dam would displace some out buildings. The canyon is quite open. The side slopes are grazed and farmed at the top. The creek dries up in late summer so only limited fishery is present.
10. Whitney Creek and Griffin Fork.
These sites were not visited. Both streams are small and likely have a limited aquatic fishery value; although, steelhead and trout are likely present. The entire area is vegetated by conifers. The elevational gradient changes quickly on both sites so the side slopes are quite steep. The streams are perennial.
11. Matrix of Impacts.
Table 9 outlines expected impacts to the environment for the proposed off-stream storage facilities. A "minus" sign indicates a negative impact. A "plus" sign indicates a positive benefit. A "zero" indicates no impact. These determinations are made based on the site visit and the limited amount of resource information available for review. Impacts to water quality downstream from the pondage area are expected to be positive since flows would augment river flows when water is needed.
Only four off-stream storage sites were studied further, based upon table 9. These four sites were Scott Canyon, Keseberg Canyon, Russell, and Whiskey Creek. They were the only sites, at this point, that had a potential positive environmental value to them (see appendix D, pages D-15 through 20)
No analysis was made as to what the sources of water would be for these four sites or what actions would be needed to move water to these storage basins. This could be either a gravity fed system or the use of pumps to store water during high-flow periods.
No determination was made as to the possible impacts these sites may have to cultural resources. This would need to be explored in detail in the feasibility phase, particularly Native American concerns. The Walla Walla District would consult closely with CTUIR to evaluate if there would be any impacts.
Table 10 indicates construction costs for these four potential off-stream storage sites.
(5) Water Exchange Project.
(a) General.
The proposed water exchange project involves pumping water from the Columbia River for discharge into irrigation ditches near Milton-Freewater, Oregon. The water will be provided to irrigators in the area in exchange for natural flows which will be left in the Walla Walla River to provide a minimum flow for fisheries enhancement. Presently, the entire flow of the Walla Walla River is diverted for irrigation purposes starting in the early spring and continuing on into the fall. The diversion is made at the Cemetery Bridge diversion structure in Milton-Freewater, Oregon (see appendix D, page D-23).
(b) Assumptions.
Assumptions for the water exchange project are as follows: Seepage into the riverbed will be included in the augmentation flow; Columbia River water would be available for the project; pumps and piping must be sized for the lowest flow anticipated during the augmentation time period; habitat enhancements to improve water quality would be pursued; and improvements to fish passage restrictions would also be pursued. As stated earlier, the Corps can also participate in the areas of improving water quality (through habitat work) and fish passage issues, if desired by the community.
(c) Study Reach, River Miles 38 to 46.
This study reach of the Walla Walla River in the Milton-Freewater area was examined to determine the flow augmentation that would be required to ensure a minimum in-stream flow through the entire reach for fisheries enhancement. This is approximately river mile 38 to 46. At the present time, especially during the summer months, the channel is often dry in this reach due to upstream diversions for irrigation.
(d) Flow Augmentation Period.
The months of April, May, and June are critical for adult spring chinook salmon upstream migration and juvenile out-migration. Therefore, these months will be the time period used for flow augmentation calculations. The flow augmentation period was determined from information included in the Walla Walla District Reconnaissance Report, Walla Walla River Basin, Oregon and Washington April 1992.
(e) Augmentation Flow.
The amount of water to be pumped for flow augmentation will be 5.9 cubic meters per second (cms) [208 cubic feet per second (cfs)]. This flow includes 1.4 cms (50 cfs) to cover channel seepage losses and 4.47 cms (158 cfs) to provide a theoretical depth of 24 centimeters (9.5 inches) of water in the river channel for fish passage. The actual depth of flow throughout the study reach will vary, but an average depth was used for a reconnaissance level flow calculation. A more involved hydraulic analysis would be required at feasibility level. The channel seepage loss was determined from information provided in the Walla Walla District Reconnaissance Report, Walla Walla River Basin, Oregon and Washington, April 1992 (see appendix A).
(f) Pumping Facilities.
Pumping facilities would consist of a primary pumping plant, a booster pumping plant, approximately 450 meters (1,476 feet) of pipe, and appurtenant power and control facilities. The possible location of pumping plants and alignment of piping is shown on
1. Primary and Booster Pumping Plant.
The primary and booster pumping plants would consist of parallel arrangements of pumps totaling 33,200 horsepower capable of pumping 5.8 cms (208 cfs). The pumps would pump against a dynamic head of 385 meters (1,263 feet). Approximately one-half of the horsepower would be required at each pumping plant, and each plant would pump against approximately one-half of the dynamic head. Fish and debris screens would be provided at the pump intake, and a discharge afterbay and control facilities would be provided at the point of discharge.
2. Piping.
Water will be pumped through approximately 49 200 meters (150,000 feet) of 150-centimeter (60-inch) diameter steel pipe. Piping will be buried with a minimum of 1 meter (3.281 feet) of cover for most of its length. Where necessary, such as at utility crossings or where undulating terrain makes burial uneconomical, other details will be used.
3. Electrical Power Facilities.
Power for operation of the pumping plants would be provided by Pacific Power & Light Company (PP&L). Power would be transmitted to the load sites over PP&L constructed transmission facilities. Estimated average annual pumping power requirements, excluding system losses, are 57,500,000 kilowatt-hours. A 2.75-km (1.5-mile) long, 69-kilovolt tap line from PP&L’s Wallula substation would be constructed to serve the primary pumping plant. A 7-km (4-mile) long, 69-kilovolt tap line from PP&L’s Touchet substation, Lowden, Washington, would be constructed to serve the booster pumping plant. Switchyard facilities would be constructed for both pumping plants.
The cost of electrical power for pumping would include the following:
The base rate charge for 3 months of continuous pumping each year (57,500,000 kilowatt-hours) would be $2,050,450. Construction costs for this alternative would be $100.64 million. This option is the largest of its kind that was considered. It may be more viable to provide a smaller amount of water through water exchange when this alternative is combined with others that provide in-stream flow.
(6) Water Efficiency Project.
Currently, nearly all irrigation canals in the WWRB are unlined, meaning they have an earth bottom to them. Of the water that is transported in these canals, some is lost through seepage into the ground water table (see plate 18 and appendix D, page D-25.)
Using this option, water that is lost through seepage in irrigation canals would be saved and then dedicated to in-stream flow. This would allow for the same acreage of land in the WWRB to stay in production but would require less water.
There are approximately 100 km (54 miles) of canals in Washington and 78 km (42 miles) of canals in Oregon. The estimated cost of lining all 178 km (96 miles) of the canals identified under this option would be from $57 to $171 million. This would allow for the return of in-stream flow water in the amount of 2.2 million m3 (76.5 million cubic feet), 770 hectare-meters (6,200 AF). This amount is calculated from an average seepage loss for irrigation channels in the WWRB. It may be found that actual losses of water are greater, which would make this option more attractive. The costs vary depending upon the type of lining material that would be chosen. Table 11 indicates the costs of the various linings.
Gunite is concrete shot out of a pressure hose that leaves a rough texture on the surface, much like concrete used in a swimming pool. The concrete is pumped, which does not require form work.
Slip-form concrete would be cast in place using forms to set the material. This is a conventional type of concrete application that has been used extensively for irrigation canals in California and Arizona. This alternative would have more durability than Gunite.
Geo-textile lining is an impervious layer of fabric that would be laid in the canal. It would require excavation upon which a base layer of rock would first be placed. Next, the geo-textile membrane would be placed, then a second layer of rock placed over the fabric to hold it in place. A disadvantage of this lining is that any leaks or breaks in the fabric would be hidden from view by the layer of rock holding it in place.
While these costs to line all 178 km (96 miles) of major canals in the WWRB are excessive, it is unlikely that all 178 km (96 miles) would need to be lined; reducing the overall cost. It would be determined in a feasibility level incremental costs analysis which canals would gain the most return in water for dollars spent. This would allow the project to determine which sections of canals would yield the most "water for the dollar." It may be possible to find additional reaches of irrigation canals that were not identified in this reconnaissance report.
There is also a legal issue to consider in the lining of canals. Some of the water that is "lost" through irrigation canal seepage is used by other irrigators whose source is groundwater. It would have to be determined to what degree this is present in the WWRB and if measures would be necessary to prevent people from losing irrigation water from underground sources.
This Water Efficiency Project option also represents the water "reality" that there is only so much water in a given basin that can be used. Other alternatives attempt to import additional water into the basin or manipulate the water regime and store water when there is "excess" water during the winter. Water saved, through the water efficiency option, will have a direct linkage to water sent down irrigation ditches and can be easily measured. With other water alternatives, it may be difficult to measure the amount of water provided to in-stream flow.
This option should have the least annual cost associated with it; however, it has not been calculated, yet. Electricity is not required to run pumps, and additional labor or effort will not be required to operate gates to release water.
Note: This discussion did not look at the issue of efficiency of measures to create improvements in the application of water to crops. Gains in water efficiency and water application can be made through changing from flood irrigation to sprinkler irrigation and from sprinkler irrigation to drip irrigation. (Drip irrigation is a system where the water is fed through pipes buried underground and released from the pipes by holes.) Further gains made in this water application can also contribute to in-stream flow.
(7) Use Existing Irrigation Canals for Fish Migration.
(a) General.
This potential project alternative involves using existing irrigation canals and ditches for spring chinook salmon migration. Water diverted from the Walla Walla River flows through a network of irrigation canals and ditches with a portion of the unused water flowing back into the Walla Walla River. The Walla Walla River channel is dry, or nearly dry, from approximately river mile 45.9 downstream to river mile 38 during the heavy irrigation season that starts in the spring and continues into the fall (see appendix D, page D-28).
(b) Assumptions.
Assumptions made for this alternative are as follows: A minimum streamflow adequate for fish migration would be maintained along the selected route; irrigation control structures can and would be modified to allow fish passage as well as maintain the irrigation function; habitat enhancements to improve water quality would be pursued by others; land use practices and in-water activities would be regulated during the fish migration season (April through June).
(c) Irrigation System Description.
1. Route.
The route chosen for salmon migration (see plate 19) starts at the Cemetery Bridge diversion in Milton-Freewater, Oregon, and proceeds downstream along the Little Walla Walla River (an irrigation ditch). At approximately 2.75 km (1.5 miles) downstream, a control structure divides the flow into the Hudson Bay canal on the left, the west prong of the Little Walla Walla River in the middle, and the east prong of the Little Walla Walla River on the right. Continuing on the east prong of the Little Walla Walla River, the flow splits into the West Crockett Branch and the East Crockett Branch. The selected route will follow the West Crockett Branch. The east prong of the Little Walla Walla River converges with the Walla Walla River at approximately river mile 37.4. The total length of the route selected from the Cemetery Bridge diversion to the convergence with the Walla Walla River is approximately 14 km (7.6 miles).
2. Irrigation District.
From the Cemetery Bridge diversion to a point approximately 7.7 km (4 miles) downstream, the Little Walla Walla River is within the boundaries of the Walla Walla River Irrigation District. The remainder of the watercourse passes through private lands but is not part of a formal irrigation district.
3. Irrigation System Description.
The majority of the Little Walla Walla River is comprised of unlined earth canals ranging in width from approximately 15 meters (49 feet) at the Cemetery Bridge diversion down to a few meters wide in the smaller irrigation canals. At road crossings and at various other locations, the canals are routed through culvert pipes or other man-made features. The original morphology of the Little Walla Walla River at many locations has been altered from its natural course to suit various purposes such as irrigation, routing around development, etc.
4. Irrigation Structures.
There are approximately 50 irrigation structures located at various points along the selected route. The structures are generally constructed of reinforced concrete with either weir boards or slide gates for flow control. Structures include main diversions that divert water to other canals in the Walla Walla River Irrigation District and structures that provide water surface elevations for pump intakes or flood irrigation for private landowners. Irrigation structures that are not designed with fish passage as a provision may also cause problems for migrating salmonids.
(d) Minimum Stream Flows.
A minimum flow of approximately .85 cms (30 cfs) is available at the Cemetery Bridge diversion structure during the spring chinook salmon migration season. The flow decreases downstream as water is withdrawn for irrigation. At the confluence with the Walla Walla River, the flow appears to be minimally adequate for fish passage, and, if not, additional water could be released into the irrigation system at the Cemetery Bridge diversion to augment flows for fish passage.
(e) Other Considerations.
There are other considerations to include. Along with an adequate supply of water and impassable irrigation structures, migrating fish would be effected by the following factors:
1. Water Quality.
An assessment of water quality issues would be required to determine if the water in the irrigation system is satisfactory for fish survival (e.g., temperature and pollution by agricultural chemical sprays and runoff).
2. Land Use Practices.
The irrigation canals and ditches pass through many private properties including rural residential, farms, and orchards. Activities such as operation of farm equipment adjacent to the canal, grazing cattle being allowed into the canal, and children playing in and around the canal should be regulated during the fish migration season to improve fish migration.
3. Poaching.
The irrigation system canals and ditches are relatively small in cross-section that would make poaching of fish easy and, therefore, a potential problem.
(f) Conclusions.
In summary, the water diverted from the Walla Walla River into the irrigation canal system provides a path that, with some modification, could be used for spring chinook salmon migration. Success for this alternative would depend upon the following:
Construction costs for this alternative would be $588,000.
(8) Trap and Haul Program.
A trap and haul program for fish is a potential project alternative that could be used to augment any of the above options to return salmon to the WWRB. As on the neighboring Umatilla River, there may be the case where additional flow is gained in the river but at minimal level. Because a sufficient amount of water is not present, the salmon would have to be physically taken from the river and transported upstream. This additional water may be enough to provide attraction flow for adult chinook salmon to enter the mouth of the river but not provide sufficient depth of water to allow migration within the stream on their own volition (see appendix D, page D-30).
A trap and haul option should not be viewed as an alternative to enhanced in-stream flows. It should be seen as a contingency plan in years of low flow or during the tail end of the migration period.
An adult fishtrap facility would be placed at Madame Dorian Park at the mouth of the Walla Walla River (see plate 20). This land is currently owned and managed by the Walla Walla District.
The fish would likely be transported above Waitsburg in the Touchet subbasin and above Milton-Freewater in the Walla Walla subbasin. No specific sites have been identified for release locations. However, ideally, there would be land that is already in the public domain that would reduce real estate costs by foregoing the need for an access easement.
One difficulty with this alternative is determining to which of the subbasins these fish would be transported. They would be trucked upstream, past the dewatered portions of the river, to either the upper Touchet or upper Walla Walla Rivers. However, unless efforts were made, it would be impossible to know which of these fish were destined for which subbasin.
A trap and haul program may require that fish from each subbasin be fin-clipped in a different manner or placement of some kind of marking device to insure that fish destined for the upper Walla Walla subbasin are not transported to the upper Touchet Basin and vice versa. Another possibility is to scale back the first reintroduction of salmon to just one of the subbasins; then it would be clear where these fish were destined.
The estimated construction cost of this alternative would be $3.9 million.
Another area of possible exploration in the feasibility phase is to examine moving the traps elsewhere in the WWRB. This is dependent upon where flows exist and where there are feasible places for locating these traps.
(9) Facilities for Reintroduction of Salmon.
The following facilities would need to be built to allow for salmon reintroduction in the WWRB (see plate 20): Hatchery on the South Fork of the Walla Walla River, adult trap at the mouth of the Walla Walla River, and salmon facilities on the North Fork Touchet subbasin. It should be noted that the facility located on the South Fork of the Walla Walla River is currently under construction. It has a design capacity to allow for salmon production for both the WWRB and Umatilla River Basin. As there is presently not a situation conducive to releasing salmon in the Walla Walla River, this facility will currently be used for just the Umatilla Basin spring chinook salmon.
The above conceptual idea for salmon reintroduction was developed from a Bonneville Power Administration (BPA) report, Northeast Oregon Hatchery Project; Conceptual Design Report; March 1995. This report described where facilities could be developed. Nothing should be considered final about these options. They only represent an opportunity to allow for salmon reintroduction in the WWRB. The hatchery on the South Fork of the Walla Walla River is currently under construction. Cost estimates were provided for an adult trap at the mouth of the Walla Walla River earlier in this reconnaissance report. The remaining missing piece to this conceptual idea involves facilities in the Touchet Basin. As shown on plate 20, these would likely be located in the North Fork Touchet subbasin. The preferred site (at this point) would be on the main stem North Fork Touchet River, downstream of the confluence of the Wolf Fork. An identified alternate site would be on the upper North Fork. It is also possible that a better site may be found in feasibility planning efforts for salmon reintroduction facilities.
The construction cost of the facilities in the NortTouchet subbasin would be $131,000. (Source for costs: BPA Northeast Oregon Hatchery Project; Conceptual Design Report; March 1995.)
None of the above alternatives in section 4.01 would be examined from a traditional economic analysis that would entail the development of benefit:cost ratios. These types of economic analyses are considered when looking at traditional Corps projects that are designed to reduce flood damages. As stated in the introduction section of this report, there was little, if any, chance that a traditional Corps project could go forth in the WWRB due to a lack of a positive benefit:cost ratio for any such project. Instead, projects that have the primary beneficiary as fish and wildlife were examined for their viability.
When designing a project for fish and wildlife benefits, the Walla Walla District would examine the possible benefits that would accrue from such a project. These benefits can be in the form of redds per kilometer of river, kilometers of riparian zone revegetated, number of nesting waterfowl, or using the USFWS Habitat Suitability Index. The question that has to be asked is, "Are the benefits gained from this alternative worth the cost?" This is, to some degree, an arbitrary definition and is a question that has been wrestled with for years in environmental restoration. Also added to the equation of determining what is the value of spending a given amount of money on an alternative, is the relative scarcity of a species.
For example, table 12 shows an initial, cursory examination of an incremental cost analysis for the salmon reintroduction alternatives. The outputs from such a product would be to determine the amount of water generated as in-stream flow for each alternative.
Water obtained for salmon restoration should not be viewed by dollar cost alone. Other non-monetary factors must be considered when determining the best way to restore salmon to the WWRB. For example, from a biological viewpoint, it is very valuable to have salmon return to a basin. Salmon juveniles can act as a food source for bull trout that may help in the recovery for that species of char. Salmon carcasses that die in the headwaters bring nutrients from the ocean back to the basin, increasing the biological productivity of the area. Salmon are an important part of Native American religion and are an important cultural icon for both Native American and Anglo communities. Costs are one factor among many that are considered in the analysis.
5.02 Flood Damage Reduction Benefits
This section examines the economics of the flood damage reduction alternatives. All benefit:cost ratio comparisons were based on 1997 price levels for projects considered in the reconnaissance study. The alternatives considered in the Walla Walla District Reconnaissance Report, Walla Walla River Basin, Oregon and Washington, April 1992, were not updated to current values, but the benefit:cost ratios computed in 1992 were so far away from unity that a major change would have been required to shift them from a low decimal to a value exceeding unity. No major changes were evident in factors that would effect either the costs or the benefits for these projects, so they were not recomputed. It is assumed that the benefit:cost ratios would be very similar to those computed in 1992.
Flood damage reduction benefits presented are the difference between the average annual flood damages that could be expected with and without the proposed projects. For all flood damage reduction alternatives, benefits are expressed as the annual equivalent of the present worth of benefits accruing over the 50-year project economic life. The Federal discount interest rate used in computing average annual damages was 7 3/8 percent. Benefits for the Waitsburg area for both Coppei Creek and the Waitsburg bypass channel projects were derived based on discharge damage data that was provided in two previous Corps Reconnaissance Reports, Reconnaissance Report, Small Flood Control Project, Lower Coppei Creek, Waitsburg, Washington, dated July of 1970; and Reconnaissance Report, Small Flood Control Project, Touchet River, Vicinity of Waitsburg, Washington, dated April of 1968. In both cases, benefits were computed for the flood event with a recurrence interval of 100 years and updated to 1997 prices. Damages estimated in Waitsburg for the Waitsburg bypass channel are somewhat overstated because they do not take into account the removal of property from the floodplain that resulted from the FEMA buyout that took place in 1997. However, this does not significantly effect the outcome of the economic analysis because the costs of the project far outweigh even the overstated benefits.
Benefits for the Mill Creek levee project were computed based on existing discharge-damage data for the Mill Creek flood control project. Without-project damages were computed based on the following scenario:
The point of zero damage is 171 cms (6,050 cfs), and the damages resulting from a 198 cms (7,000 cfs) flow are the same as the damages for an unregulated discharge of 127 cms (4,500 cfs). Of this flow, 99 cms (3,500 cfs) are released from the channel after a failure, while the remaining 28 cms (1,000 cfs) comes from the right overbank flow. Other damages are similarly computed based on the combination of the 99 cms (3,500 cfs) channel discharge, and the contribution of flow from the right overbank. (Again, this assumes that water would outflank the existing Corps project on Mill Creek.)
Benefits for the Mill Creek Dam rehabilitation alternative were also computed based on existing discharge-damage data for the Mill Creek flood control project. Benefits attributed to this project result from improving the flood control operation by decreasing the downstream regulation objective back to 40 cms (1,400 cfs). Benefits will also result from a reduction in the high O&M cost for the Mill Creek Dam since seepage problems have become apparent. Of the average O&M cost for the last 5-year period, 70 percent was assumed to be the amount that would be saved annually following construction of the project. Average annual damages prevented as a result of the change in flood control operation were $70,900. Average annual benefit from savings on O&M cost was $87,100. Total average annual benefits for this project were $158,000. The benefits computed here assume a without-project condition of diverting Mill Creek flows above 85 cms (3,000 cfs) and using available storage in the reservoir up to a maximum elevation of 385 m (1,265 feet). If the flood control operation is further restricted in the future due to increased concern over seepage, the benefits associated with the installation of the liner could rise dramatically.
Costs and benefits for all flood damage reduction alternatives are presented in tables 13 and 14.
5.03 Benefit:Cost Ratio Comparison
As shown in table 13, the benefit:cost ratios are all well below the level required to justify a project. Therefore, the projects proposed in 1992 did not qualify because of economics. In addition, environmentally, there would also be problems with the building of large storage structures in the upper parts of the WWRB. These areas are, largely, the last good habitat (refugia) that is available to native cold-water fish species (e.g., as bull trout and steelhead. Bull trout and steelhead are likely to be listed as a candidate species under the ESA in 1998. Building of an upstream storage reservoir would severely affect both of these species negatively. Off-stream storage dams built for flood control would largely avoid these environmental concerns, but off-stream sites are usually much smaller in storage capacity and cost more.
Consequently, for the above reasons, little work in the reconnaissance study was directed toward looking at the construction of dams in the headwaters of the WWRB. However, other flood damage reduction measures were considered along with the environmental restoration alternatives.
Table 14 shows the benefit:cost ratios computed for the new flood damage reduction projects evaluated in this reconnaissance report.
As shown in this table, two of the alternatives did result in benefit:cost ratios exceeding unity. Therefore, if local support exists for these projects, the reconnaissance study will recommend going forward into the feasibility study that will examine in more detail these and possibly other flood damage reduction projects within the WWRB.
Numerous contacts were made with a multitude of entities in the WWRB. Letters were received from some of the entities contacted in the WWRB (see appendix F).
The following entities were contacted by the Walla Walla District to see if they would be interested in becoming a sponsor of the project and taking the reconnaissance study into a feasibility phase:
At the date of publication, the strongest possible sponsors are the CTUIR (salmon reintroduction), WDFW (levee removal on the main stem Walla Walla River), and a potential combination of sponsors for the upper Touchet Basin from Prescott upstream. This is outlined further in section 7.
The WDFW has stated its interest in pursuing the possibility of removing levees on lands it now owns along the main stem Walla Walla River. This would have numerous environmental benefits as outlined in the previous section 4.01. There would also be benefits from reduced flooding consequences downstream by allowing the river to be reconnected to its floodplain in this reach of the river.
Additionally, there may be an interest in developing projects in the Pine Creek Basin. This interest was raised by local residents late in the study effort, but it was too late to do any analysis of possible alternatives. However, if it appears a potential sponsor may be interested in a project that will provide benefits to fish and wildlife, it is also recommended by the Walla Walla District that this be incorporated into a feasibility phase study. As identified in section 3.07 (a) and (b), there are numerous areas in the Pine Creek drainage that have opportunities for improvement.
For the upper Touchet Basin, there is Federal interest in developing a setback levee that would primarily benefit fish and wildlife. This would result from an easement or purchase that would be intended to reduce the human presence in the riparian zone.
It may be possible to have the Washington Department of Ecology serve as the sponsor for the upper Touchet Basin Feasibility Study, if this were acceptable to local governments. This would facilitate the process by having the Walla Walla District only work with one sponsor instead of a multitude.
There would also be sufficient rights acquired from the landowners along the river to allow for flooding to occur in the land within the levees. This would additionally insure water would become spread out of the river channel allowing for an improved riparian zone. Bank storage of this water would also occur to some degree, which would provide water that would be released later in the year. This would provide benefits to in-stream flow and as an ancillary benefit for irrigation.
The setback levee would also have the ancillary benefit of preventing flooding of residences and agricultural land in the area.
For salmon reintroduction, the Corps has a direct Federal interest in seeing this effort pursued in more detail through a feasibility study. As part of the Federal Government, the Corps has a trust responsibility under the Treaty of 1855 with the Walla Walla, Cayuse, and Umatilla Indian Tribes. The WWRB is part of the ceded territory these Tribes relinquished as part of the peace Treaty of 1855. As part of that trust responsibility, the Corps is required to insure that there are salmon in the rivers for the Tribes to gather. The U.S./Canada salmon treaty (Treaty between the Government of the United States of America and the Government of Canada Concerning Pacific Salmon, January 28, 1985) requires the United States to increase the number of naturally spawned salmon from United States home waters. Finally, ecosystem restoration is a Corps mission. As such, these three items make a direct linkage for Federal interest for salmon reintroduction in the WWRB.
As for a feasible potential project alternative, it appears, at this time, that water efficiency by lining of irrigation canals with an impermeable layer holds the most promise. It will have the lowest annual O&M costs. Further exploration will be required in a feasibility phase analysis to determine if enough water can be gathered using this alternative. This alternative leads to the possible addition of efficiency gains to be made in irrigation water application to crops. If it were found that sufficient water could not be gained using this alternative alone, the feasibility phase might determine that other complimentary alternatives could be added to this option.
A trap and haul facility at the mouth of the Walla Walla River should accompany these potential project alternatives. During low-water years, it may be necessary to provide transport to adult chinook salmon attempting to re-enter the river.
There are two flood damage reduction alternatives that have merit for further investigation. These are the Coppei Creek levee and the setback levee along Mill Creek near Five Mile Bridge. Both of these projects appear to have positive benefit:cost ratios, making them viable economically.
The Walla Walla District recommends that efforts be taken to negotiate three separate Feasibility Cost Sharing Agreements with the WDFW, the Washington Department of Ecology, and the CTUIR. There is also a possibility of another Feasibility Cost Sharing Agreement for Pine Creek, with the Umatilla County Soil and Water Conservation District as the likely sponsor.
If a sponsor can be identified, the area around Five Mile Bridge on Mill Creek should be investigated in a feasibility phase study. Any work in the Coppei Creek Basin should be incorporated into the feasibility study for the upper Touchet Basin.
Pursuit of these sponsorships and construction of projects to solve the problems stated above would lead to improvement of both the environment of the WWRB and the human community that it supports.
Enclosures
Table 5 - Total Storage Reach
Storage in
Hectare-MetersStorage
in AFPrescott to Waitsburg
1,050
8,700 Waitsburg to Dayton
425
3,300
Total
1,475
12,000 
(1) Sites.
Table 6 - Freshwater Life History of Hatchery Spring Chinook Salmon
(Carson Hatchery Stock)Development Stages
Month M
A
M
J
J
A
S
O
N
D
J
F
M
A
M
J
J
A
S
O
N
D
J
F
M
A
M
J
J Adult Immigration
==
==
Adult Holding
==
==
==
Spawning
Egg/Alevin Incubation
==
==
==
==
==
==
Emergence
==
==
Rearing
==
==
==
==
==
==
==
==
==
==
==
==
==
==
==
==
==
== Juvenile Emigration
==
==
==
==
Notes:
Table 7 - Costs for Storage Sites Site
Cost Mill Creek
$34,577,000 Bennington Lake Modification
$24,369,000 North Fork Walla Walla River
$64,291,000 South Fork Touchet River
$91,350,000
Table 8 - Possible Small Storage Sites Upstream Storage Site
Stream
Type of Storage
Extended Benefits Whiskey Spring
South Fork Walla Walla River
Off Stream
Flow Augmentation into South Fork Walla Walla River and Supplemental Irrigation MacDougall Camp
South Fork Walla Walla River
Off Stream
Flow Augmentation into Couse Creek and Supplemental Irrigation Cash Hollow
South Fork Walla Walla River
Off Stream
Flow Augmentation into Walla Walla River and Supplemental Irrigation South Fork Walla Walla River
South Fork Walla Walla River
In Stream
Flow Augmentation into Walla Walla River and Supplemental Irrigation Scott Canyon
South Fork Walla Walla River
Off Stream
Flow Augmentation into Walla Walla River and Supplemental Irrigation Keseberg Canyon
South Fork Walla Walla River
Off Stream
Flow Augmentation into Walla Walla River and Supplemental Irrigation Pine Creek/Dry Hollow
Walla Walla River
In Stream
Flow Augmentation into Walla Walla River Blue Creek
Mill Creek
In Stream
Flow Augmentation into Mill Creek Russell
Dry Creek
Off Stream
Flow Augmentation into Dry Creek Whiskey Creek
Touchet River
In Stream
Flow Augmentation into Whiskey Creek Whitney Creek
Touchet River
Off Stream
Flow Augmentation into Touchet River Griffin Fork
Touchet River
Off stream
Flow Augmentation into Touchet River
Table 9 - Matrix of Impacts Site
Fishery
Wetlands Habitat
Riparian Habitat
Upland Habitat
Widlife
Water Quality
Priority Whiskey Spring
0
—
—
—
+
0
-3 McDougall Camp
0
—
0
—
—
—
-4 Cash Hollow
0
0
—
0
—
+
-1 South Fork Walla Walla River
—
—
—
—
—
—
-5 Scott Canyon
0
0
0
0
+
+
+2 Keseberg Canyon
0
0
0
0
+
+
+2 Pine Creek
—
0
0
0
+
—
-1 Blue Creek
0
0
—
—
—
—
-4 Russell
0
+
0
0
+
0
+2 Whiskey Creek
0
0
0
0
+
+
+2 Whitney Creek
0
—
0
—
—
+
-2 Griffin Fork
0
—
0
—
—
+
-2 Bureau of Land Management, 1992, South Fork of the Walla Walla River
Area Plan Amendment.
U.S. Forest Service, 1990, Land and Resource Management Plan,
Umatilla National Forest.
Table 10 - Construction Costs for Potential Sites Site
Cost
Storage Capacity in Hectare-Meters
Storage Capacity
(in AF)Scott Canyon
$94.8 million
1000
8,000 Keseberg Canyon
$116.1 million
925
7,400 Russell
$12.6 million
437
3,500 Whiskey Creek
$674.2 million
612
4,900 
Table 11 - Costs for Lining Material Type
Cost Gunite
$79 million Slip-form concrete
$57 million Geo-textile linging
$171 million 
Table 12 - Salmon Reintroduction Alternatives¹ Alternative
Construction Cost²
Water Provided (in Hectare-Meters)
Water Provided (in AF)
Cost per AF of Water Provided Upstream Storage $61,290
1362
11,000
$5,570 $87,118
2375
19,000
$4,590 $21,427
1037
8,300
$2,580 $32,967
1000
8,000
$4,120 Off-Stream Storage $92,500
1000
8,000
$11,560 $113,318
987
7,900
$14,344 $11,869
437
3,500
$3,390 $64,019
612
4,900
$13,070 Water Exchange
$94,400
4637
37,100
$2,540 Water Efficiency
$56,200
775
6,200
$9,060 Irrigation Canals
$0.55
(no water provided) Trap and Haul
$2,400
(no water provided) ¹Note: This table does not reflect any O&M costs that would also have
to be factored into a complete analysis of costs. Also, considering the cost per AF of water, another
option that could be explored in the feasibility phase would be to see if there were any willing sellers of
water rights in the WWRB. If so, water likely could be obtained much cheaper than the costs stated
above.
²Numbers are in thousands.
Table 13 - Benefit:Cost Ratio of Previous Alternatives Projects¹
Total Annual Cost²
Total Annual Benefit²
Annual Net Benefit²
Benefit:Cost Ratio North Fork Walla Walla
$5,101
$110.9
$-4,990
0.02 Mill Creek
$2,764
$488.4
$-2,275.6
0.18 Bennington Lake (modified)
$1,664
$3.9
$-1,660
0.00 South Fork Touchet River
$7,236
$138.2
$-7,098
0.02 Patit Creek, Dayton
$530
$106.4
$-424.6
0.02 ¹Walla Walla District Reconnaissance Report, Walla Walla River
Basin, Oregon and Washington, April 1992. A map of the location of these potential dam sites is
located on Plate 16.
²October 1992 price levels. Costs are in
thousands of dollars.
Table 14 - Current Reconnaissance Study Flood Damage Reduction Project Benefit:Cost
Ratio Comparison Project
Average Annual Benefits
Total Annual Cost
Benefit:Cost Ratio Coppei Creek Levee
$98,600
$78,200
1.26 Waitsburg Bypass Channel
$343,200¹
$1,808,000
0.19 Mill Creek Levee
$244,900
45,000
5.44 Mill Creek Dam Renovation
$158,000
$550,600
0.29 ¹Average annual benefits do not reflect the removal of property from the
floodplain that resulted from the $1,303,500 FEMA buyout program of 1997.
Date: 10-30-97 /s/ Donald R. Curtis, Jr.
Lieutenant Colonel, Corps of Engineers
District Engineer
Appendix A - Hydrology
Appendix B - Supplemental Planning Aid Report
Appendix C - Aquatic
Appendix D - Real Estate
Appendix E - Cost Estimate
Appendix F - Letters
Appendix G - References
Appendix H - Contributors
