Prepared by
U.S. Army Corps of Engineers
Walla Walla
District
May 2001
1. INTRODUCTION
2. BACKGROUND
3. PROJECT PURPOSE AND NEED
4. ALTERNATIVE ACTIONS
4.1 Dissolved Gas Abatement Study
4.1.1 End Bay Spillway Deflectors
4.2 Preferred Alternative
4.3 Other Deflector Alternatives Evaluated
4.3.1 Extended Length Deflectors
4.3.2 Modification of Existing Deflectors
4.4 No Action
5. AFFECTED ENVIRONMENT AND
ENVIRONMENTAL CONSEQUENCES
5.1 Aquatic Species
5.1.1 Adult Salmon
5.2 Terrestrial Species
5.3 Threatened and Endangered Species
5.4 Water Quality
5.5 Cultural Resources
6. CUMULATIVE IMPACTS
7. ENVIRONMENTAL REVIEW
REQUIREMENTS
8. CONSULTATION AND COORDINATION
9. REFERENCES
FIGURE 1: VICINITY MAP
FIGURE 2: MCNARY DAM SITE PLAN
FIGURE 3: SPILLWAY BAY 1 - SECTION VIEW
This Environmental Assessment (EA) considers effects of modifying the spillway of McNary Dam which is located at River Mile 292 on the lower Columbia River, which in this region forms the boundary between southeastern Washington and northeastern Oregon (Figures 1 and 2). The southern end of the dam is in Umatilla County, Oregon and the northern end is in Benton County, Washington. Umatilla, Oregon is the closest inhabited community adjacent to the project. As required by the National Environmental Policy Act (NEPA) of 1969 and subsequent implementing regulations promulgated by the Council on Environmental Quality, this assessment is prepared to determine whether the action proposed by the Corps of Engineers (Corps) constitutes a "…..major Federal action significantly affecting the quality of the human environment…." and whether an environmental impact statement is required (PL 91-190, 42 U.S.C. 4321-4347, January 1, 1970).
Salmon runs in the Columbia River Basin have declined rapidly in recent years, leading to the listing of these runs as threatened or endangered under the Federal Endangered Species Act (ESA). In response to this decline, the National Marine Fisheries Service (NMFS), the Northwest Power Planning Council (NPPC), and other regional agencies and groups requested the Corps to spill water at the eight federal dams on the lower Snake and Columbia rivers to try to improve juvenile salmonid fish passage. Spill was just one of many methods developed and implemented in an attempt to restore the dwindling runs.
In 1989, at the request of the Northwest Power Planning Council, the Corps began spilling water at the eight Federal dams on the Federal Columbia River Power System (FCRPS) in an attempt to pass out-migrating juvenile salmon through dams more quickly. In 1994, the Corps started spilling water at NMFS’ request to try to increase passage of out-migrating juvenile salmon through the spillways in addition to routing them through the bypass systems, in a "spread-the-risk" strategy to improve salmon passage. However, spilling causes the river flows to plunge deep into the water below the dams, trapping air in the water and resulting in high concentrations of total dissolved gas (TDG). High TDG can injure or kill juvenile and adult salmon, as well as resident fish and other aquatic organisms.
In the 1970’s, in earlier attempts to reduce TDG concentrations, the Corps installed spillway deflectors at Lower Granite, Little Goose, and Lower Monumental dams on the lower Snake River and Bonneville and McNary dams on the lower Columbia River (deflectors were installed on 18 of the 22 spillway bays at McNary). The deflectors were installed as a temporary measure to reduce TDG when high flows exceeded powerhouse capacity and water had to be released through the spillway, usually during spring runoff. The deflectors were installed on the lower part of the spillway to keep the water from plunging deep into the stilling basin below the dams.
In response to National Marine Fisheries Service’s 1995 Biological Opinion, the Dissolved Gas Abatement Study (DGAS) was initiated. This study was established to examine potential methods for reducing total dissolved gas supersaturation produced by spillway operations on the eight Corps dams on the FCRPS. The DGAS was conducted in two phases. Phase One consisted of a general investigation of alternative concepts. Phase Two was a continuation of analysis and evaluations based on recommendations and study plans identified in the Phase One report. The Phase One report was published in April 1996.
Near the conclusion of Phase One, several alternatives were identified for immediate implementation. These alternatives consisted of spillway flow deflectors at Ice Harbor and John Day and spill pattern changes at Little Goose and Lower Monumental dams. The completion of ten spillway flow deflectors at Ice Harbor in 1998 and the completion of 18 spillway deflectors at John Day in 1999 lowered peak TDG production levels. The new spill patterns at Little Goose and Lower Monumental resulted in TDG reductions of 5 to 10 percent.
Because of the success of the improvements, decisions were made to move forward with the implementation of additional flow deflectors at all projects where possible concurrently with the Phase Two DGAS studies. The Dissolved Gas Abatement Fast-track (also termed Deflector Optimization) program was established and funded to accomplish this and is currently ongoing. Model investigations are underway for the addition of two spillway flow deflectors at both Little Goose and Lower Monumental, four additional flow deflectors at McNary, two additional deflectors at John Day and six additional deflectors at Bonneville. The investigation of 23 spillway flow deflectors at The Dalles is just getting underway while the Design Documentation Report (DDR) and plans and specifications for Bonneville deflectors are near completion.
The installation of spillway deflectors on end bays at McNary is also called for by the Endangered Species Act, Section 7 Biological Opinion for the Reinitiation of Consultation on Operation of the Federal Columbia River Power System, Including the Juvenile Fish Transportation Program, and 19 Bureau of Reclamation Projects in the Columbia Basin, dated December 21, 2000. The Biological Opinion presented a “reasonable and prudent alternative” (RPA) for operation of the FCRPS that identifies actions that, "combined with other ongoing and anticipated measures in the Columbia River basin, are likely to ensure a high likelihood of survival with a moderate-to-high likelihood of recovery for each of the listed species" (NMFS, 2000a). RPA Action 134 directs the Corps to "continue the spillway deflector optimization program at each FCRPS project and implement it, as warranted" (NMFS, 2000b). RPA Action 134 provides the basis for the measures contemplated in this EA.
The studies and reports referenced in Section 2, above, have identified a need to increase safe and efficient passage for threatened and endangered fish species through Corps dams on the lower Snake and Columbia rivers. The strategy for accomplishing fish passage will be to route them past the dam by one of three ways: through the turbines, over the spillway, or into bypass systems for truck or barge transport.
The purpose of this project is to reduce the amount of dissolved gas produced as river flows are passed through the McNary Dam spillway. Thus, increasing safe and efficient in-river passage of out-migrating juvenile salmon and steehead.
4.1 Dissolved Gas Abatement Study
Over 40 total dissolved gas reduction concepts or ideas (structural and operational) were generated during brainstorming sessions with regional participants. Since 1995, many of these ideas were conceptualized, designed, and tested in scaled physical hydraulic models. The alternatives had to meet four objectives: a) provide significant reduction in TDG; b) provide for high fish survival (not degrade); c) not reduce the project’s hydraulic capacity and; d) be reasonable to construct, operate, and maintain.
Ten different alternatives for TDG improvements on the eight lower Snake and Columbia river projects were evaluated in the Phase Two study. Of these alternatives, four were investigated for their potential to meet the State and Federal Water Quality Standards. They include:
Six other alternatives were investigated for their ability to provide incremental improvements in TDG supersaturation with the realization that alone they would not meet the State and Federal Water Quality Standards. They include:
Conceptual designs were developed for each alternative. Hydraulic model investigations were conducted for those designs with uncertainties. The TDG performance of each alternative was then estimated based on field-investigations of prototype structures and hydraulic conditions observed and measured within the physical hydraulic models.
Results of the hydraulic analysis and model investigations were used to refine the conceptual designs as needed. Before applying these design concepts to individual projects, they were evaluated for: (1) Ability to maintain spillway capacity up to the spillway design flow (SDF); (2) Adequate energy dissipation of all project releases up to and including the SDF; (3) Emergency closure capability of all operating conduits and/or other flow control structures, and; (4) Construction and operational feasibility.
The most promising alternative designs were then developed for possible application at each of the eight Corps dams. Conceptual layout, construction cost estimates, construction schedules, and TDG estimates were prepared.
Based on the level of design detail, all alternatives appeared feasible to construct and operate. The baffled chute spillway, side channel spillway and submerged conduits alternatives have the greatest potential to achieve State and Federal Water Quality Standards. However, the only alternatives expected to achieve safe or acceptable fish passage conditions while providing for significant gas reduction benefits are the additional/modified deflectors, powerhouse/spillway separation wall, submerged spillway gates and additional spillway bays. Because of the high risk to juvenile and adult salmonids, none of the other alternatives were recommended for further consideration or development.
The alternatives can be grouped as either short-term alternatives or long-term alternatives. The short-term alternatives are those that are considered to be of conventional design, with proven benefits, less expensive, and can be implemented more quickly than long-term alternatives. The short-term alternatives consist primarily of additional deflectors and operational spill pattern changes. These alternatives have proven benefits and the anticipated risk to fish is acceptable. Long-term alternatives will require additional study and possibly prototype testing to assess their acceptability and confirm their anticipated TDG performance. Therefore they were removed from further consideration for this project.
4.1.1 End bay Spillway Deflectors
End bay spillway deflectors are recommended at McNary by both the DGAS study and the 2000 Biological Opinion. Physical hydraulic model studies were used to examine a number of deflector alternatives to identify a design that would provide optimum performance in reducing the production of TDG. Various configurations of deflectors were evaluated including deflector shape and elevation. In addition, the deflectors currently installed on interior spillbays were evaluated for potential improvements. Installation of end bay spillway deflectors will not preclude future studies or the potential future installation of other longer term and possibly more effective TDG reduction alternatives. Installation of end bay spillway deflectors will produce an immediate TDG reduction benefit while other longer-term alternatives are being studied and evaluated in more detail. The DGAS and its alternatives evaluation is incorporated by reference and is available by CD if requested from the Walla Walla District Corps of Engineers.
4.2 Preferred Alternative
The preferred alternative is to construct new spillway deflectors on end bays 1, 2, 21, and 22 and to install four new spillway gate hoists at McNary Dam. The spillway consists of 22 spillway bays. Twenty-one spillway bays are operational and bays 3 through 20 currently have deflectors. The existing deflectors are 12.5 feet long and have been constructed at elevation 256.0 mean sea level. They do not have a smooth radius transition and do not have pier nose extensions. Spillway bay 22 has been closed to allow barge loading from the old juvenile fish facility and can easily be made operable by adding a new gate hoist. The new deflectors will be 12.5 feet in length and will have a smooth transition radius of 15-feet from the spillway ogee to the horizontal deflector face. The radiused transition does not appear to provide TDG performance improvements but it may reduce the potential for fish injury. Adding transitions to new deflectors does not substantially change the construction costs of the overall deflector installation. The deflectors will be installed at elevation 256.0, (±3 feet) mean sea level (physical hydraulic model studies are currently being conducted to determine the optimum elevation for each deflector. The final selected elevations will be provided to the contractor following contract award). The new deflectors would be shaped somewhat like a shelf with a vertical downstream face and a slightly curved top (Figure 3) to force spilled water to flow horizontally (skimming flow) rather than plunging to the bottom of the stilling basin. Each deflector would extend across the 50-foot width of the spillbay. Construction of end bay spillway deflectors and associated spill pattern changes are anticipated to result in reductions in total dissolved gas production of 3 to 5 percent during spillway operations.
The Corps may construct the total deflector project in two phases. Phase One of construction is anticipated to occur from October 1, 2001 until March 31, 2002. This phase of the construction would provide for installation of the four gate hoists and the four end bay deflectors. It is desirable to construct during the fall because the risk of high river discharges and associated spillway operations is very low. However, the risk of high river discharges and potential spill operations increases for the December through March time period. If substantial spill is required during the construction of the deflectors, it is highly likely that the contractor will be required to stop work and vacate the spillway area due to safety concerns. It is anticipated that construction of the four deflectors and installation of the gate hoists will require a minimum of 5 months. Phase Two of the construction is optional, but would likely occur from October 1, 2002 until March 31, 2003. Phase Two would involve construction of ancillary features which may be needed to mitigate for adverse effects created by operation of end bay spillway deflectors. Likely structures would be extension of spillway training walls to correct for adverse tailrace eddy conditions. Should these be required, a supplement to this assessment will be prepared.
The Corps has identified one way the spillway deflectors could be constructed although the actual method to be used will be up to the contractor. Since each of the four end bay spillway bays are isolated by training walls extending into the spillway stilling basin, one of the quickest ways to construct the deflectors would be to fabricate steel bulkheads which would be installed in existing fishlead guide slots in the existing training walls at bays 1, 2, 21, and 22. A barge-mounted crane will likely be used to set the bulkheads. Once the bulkheads are in place, the stilling basin work area between the training walls, newly installed steel bulkhead and the spillway ogee can be dewatered. Work on the deflectors can then be accomplished in the dry. Some water leakage is usually present so pumping to maintain a dewatered condition will likely be maintained throughout the construction period. Construction may occur on more than one spillbay at a time. The contractor may also choose to dewater only a portion of the work area and work from a floating platform.
The contractor will use a combination of saw cutting, drilling and splitting to remove concrete from the face of the existing spillway, leaving a roughened surface for placement of the deflector concrete. The removed concrete will be captured and not allowed to fall into the tailrace pool. Concrete anchors will be drilled and grouted into the face of the spillway followed by installation of reinforcing steel. Concrete formwork will be installed and concrete for the deflectors placed. All seepage water and other water from construction operations will be removed from the work area for settling or other appropriate treatment. Should the need arise to spill water during construction, any floating support barges outside of the work area will need to be removed, but depending on levels of spill, construction may be able to continue since the construction areas are isolated from the river. If spill is high, then it is likely that work will need to be suspended for safety reasons. It may be possible to direct spill toward the center of the spillway to avoid spilling in bays adjacent to the ongoing construction. This may allow construction to continue. If spill is required during the construction period and spill discharge is directed toward the center of the spillway, utilizing only a few center spillbays, it is likely that TDG production could be higher than if the spill discharge were spread out evenly on all bays. However, during this time of year, few if any, salmonid fish are present and the effects are anticipated to be of short duration and minimal.
The four new spillway gate hoists will be installed to facilitate the ability to change spill patterns. The gate hoists would be constructed off-site and delivered to McNary Dam. They will be set into place up in the spillbay using a crane. There are no construction impacts anticipated.
The Corps plans to complete construction of the four end bay deflectors in time for the spring 2002 out-migration. At that time, the Corps would operate the spillway in the normal manner for spring runoff flows or would voluntarily spill water as recommended by NMFS for fish passage.
4.3 Other Deflector Alternatives Evaluated
4.3.1 Extended Length Deflector. A 17.5-foot horizontal deflector was evaluated to determine if a longer length would increase the effective operational range of deflector performance. Model studies were conducted over a wide range of operational spill and tailwater conditions and the deflector was adjusted in elevation for a variety of conditions. Performance curves were developed and compared against similar curves developed for the standard 12.5-foot deflector. No additional performance was gained from the 17.5-foot deflector and the anticipated construction cost of the longer deflector was more than that of the 12.5-foot length. Hence, the 17.5-foot deflector was dropped from further consideration.
4.3.2 Modification of Existing Deflectors. Performance curves were developed for the existing deflectors using anticipated future operational spill and related tailwater elevations. The existing deflectors were found to be optimal at their existing elevations and current geometric configuration. Radiused transitions were considered as a potential modification to the existing deflectors, however, no performance gain in TDG production was found. Radiused transitions may help reduce fish injury, however, no biological evidence exists to justify the large investment which would be required to implement radiused transitions on existing deflectors. Hence no modifications to existing deflectors are recommended.
4.4 No Action
Under this alternative, the Corps would not construct end bay spillway deflectors nor install gate hoists. Operational spill pattern changes would not be possible without the hoists or installed additional end bay deflectors. The Corps would continue to operate the spillway for passing excess flows that could not be passed through the powerhouse, but operational spill pattern changes would not be possible without the hoists or installed additional end bay deflectors. The Corps would continue to spill water during the spring out-migration period as requested by NMFS. TDG would continue to be produced at high levels during spill increasing the risk to fish. The Corps would continue to study and design more viable TDG abating concepts for future construction and operation at McNary Dam.
5.1 Aquatic Species
Many aquatic species live in the Columbia River in the project area. There are up to 35 resident fish species including rainbow trout, walleye, yellow perch, bass, bluegill, bull trout, crappie, northern pikeminnow, channel catfish, and several sucker species. Anadromous fish species include spring/summer chinook, fall chinook, sockeye, steelhead, coho, white sturgeon, Pacific lamprey, and American shad. Currently, runs of coho run up to the Clearwater, Yakima, and Methow rivers and therefore are seasonally found in the vicinity of McNary Dam. These runs are not ESA listed because they are a re-introduced species. Snake River spring/summer chinook and fall chinook are listed as threatened species under the ESA while upper Columbia River spring chinook are endangered. Mid-Columbia and Snake River steelhead are threatened, while upper Columbia River steelhead are endangered. Snake River sockeye salmon are listed as endangered.
Construction of the spillway deflectors would have minimal impacts on aquatic resources in the vicinity of the dam. No critical fish habitat would be negatively impacted by the construction. There is a possibility that turbidity may increase slightly as the bulkheads are put in place. Fish and other organisms in the river would easily avoid the construction activities. Any fish inadvertently trapped in the work area would be salvaged by qualified personnel and released back into the river.
There is an extremely remote possibility that high river flows during the construction period could force the Corps to spill water over the spillway into the construction work area. Spill would only be allowed to occur in the bays under construction as a last resort because it would damage the work in progress and would be very hazardous to juvenile fish passing over this portion of the spillway. If spill were allowed in the work area, juvenile fish could be exposed to non-uniform concrete surfaces and steel anchors depending on the state of deflector completion. There are 18 other spillbays and 14 powerhouse turbines that can pass high volumes of water. These alternative routes for passing water would be fully utilized before any water is allowed to pass into the construction work area.
Operation of the additional four end bay spillway deflectors and associated operational spill pattern changes (made possible by additional four gate hoists) is expected to decrease TDG production (when compared to current spill levels). This would improve in-water conditions for salmon as well as other aquatic organisms. Dissolved gas levels are of concern because gas supersaturation can lead to the development of “gas bubble disease” in fish and aquatic organisms. This condition can produce a variety of physiological changes that can be fatal. Adult salmon are more susceptible to the effects of TDG supersaturation than juveniles due to their more developed organs. In addition, high gas saturation levels may cause prey organisms for juvenile salmonids to float away from rearing and staging areas.
Spill at McNary Dam, both involuntary during high flows and voluntary for fish passage, can cause TDG supersaturation that exceeds 110 percent. In recent years the Corps has operated the dam under a temporary waiver from the Washington State water quality standards that allows TDG up to 120 percent. ESA considerations prompted the waiver, so that spill volumes would continue for the purpose of increasing juvenile fish passage. Research indicates that TDG concentrations above 120 percent can be lethal and lead to death or chronic physiological stress in juvenile salmon when exposed and held in shallow water conditions where they cannot depth compensate. Adult salmon are negatively affected at TDG below 110 percent (if exposed and held in shallow water conditions where they cannot depth compensate). For similar spill operations, the Corps estimates that installing the additional four deflectors and adjusting operational spill patterns, the TDG production will be reduced by 3 to 5 percent. If the additional four deflectors coupled with operational spill pattern changes reduce TDG then adult and juvenile salmon in-river survival could be increased.
The exact impact of the end bay spillway deflectors on passage conditions for juvenile salmon going through the spillway at McNary Dam is unknown. Turbulence in the vicinity of stilling basin baffle blocks and the endsill may be increased with the addition of the end bay spillway deflectors. This could cause increased mechanical injury and decrease survivability of juvenile salmonids migrating downstream. However, the 2000 Biological Opinion issued by NMFS directs the Corps to "conduct physical and biological evaluations to ensure optimum gas abatement and fish passage conditions" (NMFS, 2000c). In-river passage conditions for salmon and steelhead are more likely to improve with the construction of end bay spillway deflectors. In addition to reducing TDG volumes, deflectors tend to produce a "skimming-like" flow along the surface of the water that may be sufficient to safely carry juvenile salmon across the top of the concrete baffles and the downstream edge (endsill) of the stilling basin.
5.1.1 Adult Salmon
McNary Dam has two fish ladders to provide passage for adult salmon migrating upstream to spawn. The entrance to the north ladder is adjacent to the north side of spillbay one while the south ladder entrance is adjacent to the south side of spillbay 22. Since adult salmonids are attracted to strong flows, attraction water is provided at the entrance of each ladder to help the adults find the ladders. Operation of the spillway deflectors and associated spill pattern changes may impact adult salmon passage conditions. Model studies and prototype evaluations have shown deflectors coupled with spill pattern changes in the outside spillway bays can create strong cross currents (or lateral flows) immediately downstream of the adult fishway entrances. Tailrace conditions altered by additional deflectors and spill pattern changes may disorient and delay adult fish seeking passage through the fishway entrances adjacent to the spillways. The effect of additional flow deflectors and spill pattern changes on adult fish passage was evaluated for this project accounting for differences in configurations (e.g., relative location of fishway entrances, channel bathymetry, and the existence of guide walls separating the entrances from the stilling basin). The design elevation for the deflectors adjacent to fishway entrances at McNary may be adjusted to allow slightly more energy dissipation to occur and spill volumes in spill bays adjacent to ladder entrances may be limited operationally. This action will serve to minimize adverse hydraulic impacts and potential delays to adult fish migrating upstream. Adult fish present in the tailrace will also benefit from the reduction of TDG expected from installation of the additional end bay deflectors.
5.2 Terrestrial Species
Many species of mammals, birds, amphibians, and reptiles inhabit the project area for part of, or the entire year. Mammals common to the area include mule deer, beaver, muskrat, marmots, mink, raccoon, skunk, and weasel. These mammals mainly utilize the shoreline and brushy areas of the reservoir. Badgers occupy the open rangeland. Otters have been occasionally observed in the project area. Common birds include waterfowl such as Canada geese and mallards, upland game birds, mostly California quail, ring-necked pheasant, and some Hungarian partridge. There is also a fairly large chukar and mourning dove population. The steep basalt cliffs of the project area afford nesting habitat for many of the river’s raptors. These include the red-tailed hawk, golden eagle, bald eagle, great horned owl, and others. Marsh hawks, burrowing owls, and short-eared owls nest in the open rangeland and marshy areas.
Construction activities would not impact wildlife use in the project area. Construction activities would take place when birds are not nesting. Any birds in the area would easily be able to avoid the work activities.
Operation of the deflectors would not negatively impact wildlife use at the dam. Birds would generally avoid the areas of water turbulence.
5.3 Threatened and Endangered Species
As mentioned in Section 4.1, there are a number of National Marine Fisheries Service (NMFS) ESA-listed fish species that migrate past McNary Dam. The Corps has written a coordination letter to NMFS stating that our determination of construction of the spillway deflectors is: "May affect, not likely to adversely affect" listed species. A copy of this letter is attached as Appendix A. The Corps proposes installing the spillway deflectors as per the Biological Opinion for the Reinitiation of Consultation on Operation of the Federal Columbia River Power System, Including the Juvenile Fish Transportation Program, and 19 Bureau of Reclamation Projects in the Columbia Basin, prepared by NMFS on December 21, 2000.
The Corps is also required to consult with the U.S. Fish and Wildlife Service (USFWS) for actions that may jeopardize the existence of listed species. The Corps has identified two USFWS ESA-listed species that could be present in the project area. They are the wintering bald eagle and the bull trout. No impacts to individual bald eagles are anticipated by the construction and operation of the proposed project. There are no known bald eagle nesting or perching sites in the vicinity of the project area. The proposed work site is already disturbed and is a center of human activities. Any eagles in the vicinity of the project would be passing through and would easily avoid the construction site. The construction and operation of the spillway deflector project would not affect habitat or food sources for eagles. Based on the fact that the project is in a highly developed site with constant human activity, the Corps has made a "No effect" determination.
According to the Washington Department of Fish and Wildlife (WDFW), no bull trout were observed passing by the adult fish counting windows at McNary Dam in the past ten years and none were observed in the daily smolt monitoring samples from 1993 to the present (per telephone conversation on April 3, 2001 with Steve Richards of WDFW, who is the Adult Fish Count Supervisor for the Walla Walla District Corps of Engineers). Within the past ten years, one bull trout was observed swimming above the bars in the juvenile fish separator. Bull trout have never been reported as a counted fish species in the Corps of Engineers Annual Fish Passage Reports that list salmon, steelhead, and incidental species that pass the McNary adult fish counting windows (USACE). Since there are only a few, if any, bull trout in the project area, the Corps has written a coordination letter to the USFWS stating that our determination of construction of the spillway deflectors is: "May affect, not likely to adversely affect." A copy of this letter is attached as Appendix B.
5.4 Water Quality
Water quality is measured by many parameters and methods, but for the McNary Dam area, of most concern are, total dissolved gas (oxygen, nitrogen, argon, and carbon dioxide), temperature, turbidity, pH, and nutrients. The purpose of the project is to reduce the TDG levels during periods of spill. This is the only parameter that is expected to change after implementation of the deflectors.
Construction is not expected to have any measurable effects on any water quality parameters. Bulkheads would be used to isolate the work areas from the river. All seepage water and other water from construction operations will be removed from the work area for settling or other appropriate treatment.
In compliance with the Clean Water Act, the Corps has requested 401 Certification from the Washington State Department of Ecology (see Appendix C).
5.5 Cultural Resources
The entire area covered by the McNary project is rich in evidences of early civilizations. The transportation and fishing provided by the rivers, the relatively mild climate, and the abundance of game in the area attracted settlement by peoples of many early civilizations. However, the construction of McNary Dam in the 1940’s effectively removed any archaeological sites that once existed in the project area, thus significantly altering the landscape surrounding the dam.
Construction of end bay spillway deflectors and installation of gate hoists does not have the potential to adversely impact known historic properties (McNary Dam is not yet 50 years old). A staging area for concrete mixing and materials storage will be used for the length of the project. One of the staging areas under consideration is located on the Washington side of the river, a second staging area, preferred for use, is located on the Oregon side of the river. Although the proposed construction in the spillway has no potential to adversely impact McNary Dam, the Corps of Engineers will complete a cultural resource review and consult with the Oregon State Historic Preservation Officer before the project is initiated to determine what, if any, potential effects may be caused by the project at each of the staging areas (See Appendix D).
The National Environmental Policy Act and the Council on Environmental Quality regulations require Federal agencies to consider the cumulative impacts of their actions. Cumulative impacts are defined as "the incremental impact of the proposed action when added to other past, present, and reasonable foreseeable future actions, regardless of what other agency or person undertakes the other actions. Cumulative impacts can result from individually minor, but collectively significant, actions taking place over a period of time" (40 CFR 1506.7).
There are no negative cumulative impacts due to the construction of end bay spillway deflectors at McNary Dam. Construction impacts are of a short-term nature and would not produce a cause-and-effect relationship of resources.
There are positive cumulative impacts of operation of end bay spillway deflectors at McNary Dam. The overall benefit achieved from installing end bay deflectors is that TDG in the tailrace would be reduced. With spillway deflectors also in use at the four upstream lower Snake River dams and the three downstream lower Columbia River dams, TDG in the entire FCRPS could be reduced substantially, presumably increasing in-river salmon survival. The goal of the Deflector Optimization Program that is funded and currently ongoing, is to implement additional flow deflectors at all FCRPS dams where possible. At Ice Harbor Dam (the first dam upriver of McNary on the Snake) there are already spillway deflectors on all ten spillway bays. At Lower Monumental Dam there are deflectors on 6 of the 8 bays with plans to install deflectors on end bays 1 and 8 beginning in October 2002. Little Goose Dam also has deflectors on 6 of the 8 bays with future plans to install deflectors on end bays 1 and 8. Lower Granite Dam (the uppermost dam on the lower Snake River) has spillway deflectors on all 8 bays, although the design of those deflectors may need to be modified in the future. On the lower Columbia River at John Day Dam, two end bay spillway deflectors will be installed during the 2001-2002-winter work window. At The Dalles Dam there is currently a "combined deflector and spillway survival study" underway to determine the best course of action to improve in-river salmon survival rates. Installing spillway deflectors at The Dalles Dam may not be beneficial to fish. Construction of deflectors on end bays 1, 2, 3, 16, 17, and 18 at Bonneville Dam will begin in October 2001 and be complete by mid-April 2002. Bonneville Dam currently has deflectors on center bays 4 through 15.
The following paragraphs address the principal environmental review and consultation requirements applicable to Corps of Engineers civil works actions. Pertinent Federal statutes, executive orders, and executive memorandums are included.
7.1 Federal Statutes
The construction of end bay spillway deflectors and installation of gate hoists described in the preferred alternative does not have the potential to adversely impact known historic properties (McNary is not yet 50 years old). Although the proposed construction in the spillway has no potential to adversely impact McNary Dam, Corps of Engineers Cultural Resources Staff will complete a cultural resource review and consult with the Oregon State Historic Preservation Officer before the project is initiated to determine what, if any, potential effects may be caused by the project staging areas. The Cultural Resource Inventory Report and letters to the Washington and Oregon State SHPOs are attached as Appendix D.
The project would comply with the Clean Air Act, as amended. The construction would cause only temporary and minor effects of the quality of air. This would result from the operation of motorized vehicles and equipment. Dust would be kept at a minimal level with the aid of dust control measures.
Placement of temporary bulkheads and construction of the spillway deflectors will be subject to the requirements of the Clean Water Act. Placement of temporary bulkheads is evaluated under Nationwide Permit Number 33, Temporary Construction, Access and Dewatering. Construction of the deflectors is evaluated under Nationwide Permit Number 25, Structural Discharge, as the concrete and grout for these structures will be placed in tightly sealed cells. However, the project does not meet State Regional General Condition 10, Fills Within 100-Year Floodplains, therefore the Corps is requesting water quality certification from the Washington State Department of Ecology. The request letter to Ecology is attached as Appendix C.
See Section 4.3. The Corps has determined that construction and operation of the proposed project would have "No effect" on listed wildlife species. The Corps has also determined construction of the proposed project "May affect but not likely to adversely affect" listed salmon stocks or bull trout. See Appendix A and B.
This EA was prepared as required by the Act. No significant impacts have been identified at this time. If no significant impacts are identified during the public review process, an EIS would not be required. If an EIS is not required, full compliance with NEPA would be achieved once the Finding of No Significant Impact (FONSI) is signed.
This segment of the Columbia River is not included on the inventory of wild and scenic rivers.
The project does not conflict with the purposes and goals of the Act.
Under this Act, Federal agencies proposing water resource development projects are required to coordinate with the USFWS for evaluation of effects the project may have on fish and wildlife resources. The Corps has determined that a Coordination Act Report is not required for this project as it is mainly operational in nature.
This Act prohibits constructing bridges, dams, dikes, or causeways over harbors or navigable waters of the United States without approval of the Corps of Engineers. The Act also prohibits any obstruction to the navigable capacity of any waters of the United States. Construction of end bay spillway deflectors and installation of gate hoists will not obstruct the navigable capacity of the waterway.
7.2 Executive Orders
The objective of Executive Order 11988, is to insure that to the best of our ability we avoid any adverse impacts, short and long term, with relation to the occupancy and modification of the base floodplain whenever there is a proposed alternative. This project would not result in or support additional development in the floodplain. Therefore, the project is in compliance with the Executive Order.
No wetlands will be impacted by this project.
7.3 Executive Memorandums
No agricultural land will be affected by this project.
This project has been coordinated with applicable agencies including the US Fish and Wildlife Service, the National Marine Fisheries Service, the Environmental Protection Agency, the Washington Department of Fish and Wildlife, and the Washington State Historic Preservation Office. Additionally, the EA has been distributed to interested Federal and State agencies, groups, and the public for review and comment.
NMFS, 2000a. "Endangered Species Act Section 7 Biological Opinion on the Reinitiation of Consultation on Operation of the Federal Columbia River Power System, including the Juvenile Fish Transportation Program, and 19 Bureau of Reclamation Projects in the Columbia Basin." Page 9-1.
NMFS 2000b. "Endangered Species Act Section 7 Biological Opinion on the Reinitiation of Consultation on Operation of the Federal Columbia River Power System, including the Juvenile Fish Transportation Program, and 19 Bureau of Reclamation Projects in the Columbia Basin." Page 9-124.
NMFS 2000c. "Endangered Species Act Section 7 Biological Opinion on the Reinitiation of Consultation on Operation of the Federal Columbia River Power System, including the Juvenile Fish Transportation Program, and 19 Bureau of Reclamation Projects in the Columbia Basin." Page 9-124.
U.S. Army Corps of Engineers (USACE). "Annual Fish Passage Reports", 1954-2000. Portland and Walla Walla Districts.
Planning, Programs, and Project
Management Division
Mr. Jim Ruff
National Marine Fisheries Service
Environmental and Technical Services Division
525 N.E. Oregon Street, Suite 500
Portland, Oregon 97232
Dear Mr. Ruff:
Construction
Effects
Summary
Planning, Programs, and Project
Management Division
Mr. Kemper McMaster
US Fish and Wildlife Service
2600 SE 981 Avenue, #100
Portland, Oregon 97266
Dear Mr. McMaster:
Construction
Effects
Summary
Planning, Programs, and Project
Management Division
Ms. Cathy Reed
Washington State Department of Ecology
Central Regional Office
15 West Yakima Avenue
Suite 200
Yakima, Washington 98902-3452
Dear Ms. Reed:
INTRODUCTION
PROJECT DESCRIPTION
Figure 1. A portion of the USGS topographic quadrangle Umatilla, Oregon - Washington 1993 depicting the location of McNary Dam and activity areas associated with this proposed project (T. 5 N., R. 28 E., Sections 3 and 10).
LITERATURE REVIEW/CONTEXT STATEMENT
Known Cultural Resources
Previous Archaeological Studies
RESEARCH DESIGN
FIELD INSPECTION
RESULTS AND RECOMMENDATIONS
Given this finding, it is recommended that the project proceed as planned.
REFERENCES
| Aston, Anneli | |
| 2001 | Draft McNary Spillway Deflector Environmental Analysis. Walla Walla District. Walla Walla, Washington. |
| Burtchard, Greg, et al. | |
| 1981 | Test Excavations at Box Canyon and Three Other Side Canyon Sites in the McNary Reservoir. Laboratory of Archaeology and History. Washington State University. Pullman, Washington. |
| Dickson, Catherine. | |
| 1999 | McNary Reservoir Cultural Resource Inventory Survey Report. Cultural Resources Protection Program. Confederated Tribes of the Umatilla Indian Reservation. Pendleton, Oregon. |
| Drucker, Philip | |
| 1948 | Appraisal of the Archeological Resources of the McNary Reservoir, Oregon and Washington. Columbia Basin Project River Basin Surveys. Smithsonian Institute. Washington D.C. |
| Jaehnig, Manfred | |
| 1999 | Cultural Resource Site Erosion Assessment Along the McNary Dam Reservoir, Umatilla County, Oregon, and Benton, Franklin and Walla Walla Counties, Washington. Cultural Resources Protection Program. Confederated Tribes of the Umatilla Indian Reservation. Pendleton, Oregon. |
| Keith, Mary | |
| 1999 | McNary Yacht Club Sewer System Improvement Cultural Resources Inventory Report. Walla Walla District. Walla Walla, Washington. |
| Osborne, Douglas | |
| 1957 | "No. 8. - Excavations in the McNary Reservoir Basin Near Umatilla, Oregon. " Smithsonian Institution Bureau of American Ethnology. Bulletin 166. Government Printing Office, Washington D. C. |
| Schalk, Randall | |
| 1980 | Cultural Resource Investigations for the Second Powerhouse Project at McNary Dam, Near Umatilla, Oregon. Laboratory of Archaeology and History. Washington State University. Pullman, Washington. |
| Steinmetz, Shawn | |
| 1999 | McNary Interceptor Sewer Line Extension Umatilla County, Oregon. Confederated Tribes of the Umatilla Indian Reservation. Pendleton, Oregon. |
| Tracy, Ray | |
| 1996 | Cultural Resource Inventory Report Washington D. E. M. Warning Siren at McNary Dam Walla Walla District, Corps of Engineers. Walla Walla District. Walla Walla, Washington. |
| U.S. Army Corps of Engineers | |
| 1982 | Cultural Resources Management Plan for the Walla Walla District. Walla Walla District. Walla Walla, Washington. |
Planning, Programs, and Project
Management Division
Leland Gilsen, Ph.D.
State Historic Preservation Office
525 Trade Street SE
Salem, Oregon 97310
Dear Dr. Gilsen,
Planning, Programs, and Project
Management Division
Dr. Robert Whitlam
Department of Community Development
Office of Archaeology and Historic Preservation
111 21st Avenue SW.
Olympia, Washington 98504-8343
Dear Dr. Whitlam:
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