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Santa Maria Project
State: California
Region: Mid-Pacific
Related Documents
Santa Maria Project History (43 KB)
Related Facilities
Related Links
South-Central California Area Office
Twitchell Dam
California Data Exchange Center End-of-Month Storage for Twitchell Reservoir
Weather Conditions (NOAA)
Precipitation
Cuyama River near Santa Maria, California (USGS)
Spring and Summer (NRCS)
Mountain Snowpack Maps for Great Basin & California
Palmer Drought Index Map
Explanation of Palmer Drought Severity Index (Text)
Cuyama River below Twitchell Dam, California (USGS)
Cuyama
Twitchell Dam
Regional Precipitation
General
The Cuyama River, with its principal tributaries Alamo Creek and Huasna River, is the main source of water for the project. The drainage basin, comprising approximately 1,135 square miles above Twitchell Dam, lies along the southern boundary of San Luis Obispo County and the northern edge of Santa Barbara County. All water used within the area is obtained by pumping from the ground-water reservoir. The Santa Maria Project is one of three `seacoast projects`capture the seasonal floodwaters that would otherwise `waste to the sea.` The others are the Cachuma (http://www.usbr.gov/dataweb/html/cachuma.html) and Ventura River (http://www.usbr.gov/dataweb/html/ventura.html) Projects. The Santa Maria Project is about 150 miles northwest of Los Angeles, California. Authorized in 1954, this water conservation and flood control project also provides full and supplemental irrigation water to approximately 35,000 acres of cropland. Reclamation constructed Twitchell Dam and Reservoir, formerly called Vaquero Dam and Reservoir, and the U.S. Army Corps of Engineers constructed a system of river levees.
History
The area was devoted to cattle ranching until the great droughts of 1862-1864 caused a decline in the industry. In about 1867, settlers arrived and introduced new types of agriculture. Grain production soon developed into an important industry, and fruit and bean crops were started. By 1900, fruit production began to decline, mostly from the unfavorable climate. Cattle raising continued to be prominent since a major part of the watershed was suitable for grazing. Irrigation was introduced in 1897 when the Union Sugar Company of San Francisco began growing sugar beets near Betteravia. Development of artesian wells to irrigate the beets offered new opportunities, which led gradually to the establishment of intensive vegetable growing. In 1898, a company was organized to take water from the Sisquoc River and transport it east by gravity canal to the city of Santa Maria and adjacent lands. Several years later a flood destroyed the dam and headgates, discouraging further efforts in this method of irrigation. During the 1920`s, the crop pattern shifted from beans and grain to vegetables and flower seeds. Irrigated agriculture is now attained by pumping from wells.
Construction
Construction of Twitchell Dam was started in July 1956 and completed in October 1958. During the construction period, the name of Vaquero Dam and Reservoir was changed to Twitchell Dam and Reservoir through the efforts of the Santa Maria Valley Water Conservation District and Board of Supervisors of Santa Barbara County, with the concurrence of the Board of Geographic Names and Reclamation. As part of the project, the Corps constructed a series of levees and channel improvements along the Santa Maria River to protect the city of Santa Maria and the Santa Maria Valley. Twitchell Reservoir impounds winter floodwaters for later release down the river channel at a predetermined rate for maximum percolation into the ground-water reservoir. Individual landholders pump water from this reservoir. The principal irrigated products of the project area are field crops, including lettuce, beans, broccoli, carrots, and potatoes; vegetable and flower seeds; and irrigated pasture. Flood control benefits are achieved through storage of winter floodwaters in Twitchell Dam. The beautiful, broad Santa Maria Basin opens eastward from the Pacific Ocean toward the Sierra Madre Mountains where the sources of the rivers that sculpted the valley lie. Upon viewing such fertile grandeur, sea-going travelers as far back as the the eighteenth- and nineteeenth-centuries were so impressed that they described the area as a future agricultural paradise. Years later, corporate interests would see opportunity in the valley`s deep, alluvial soil and extensive underground fresh water supply, constructing the first, albeit short-lived, irrigation project in Santa Maria. Before long, though, such bounty brought forth problems. By the 1930`s, farmers were pumping for water deeper, more often, and at more expense than ever before. Floods often plagued Santa Maria`s wide, low-lying floodplain of a valley. Consultants were brought in and told locals that they were pumping the aquifer faster than it was being naturally replenished and that if they continued to do so salt water might intrude upon their source. First, Santa Marians needed to recharge their aquifer resource. If they built levees and cleared the river channel they might also be able to protect their property from floods. At about the same time, local water developers such as T.A. `Cap` Twitchell and `Brad` Bradbury (after whom the Cachuma Dam was renamed) were just beginning to learn how to build large, local water projects. The desperately thirsty residents of the Santa Barbara area were first in line and got their needs quenched in 1948 with the Cachuma Project authorization. Santa Maria wanted their own `Cachuma` for the northern portion of the county. Not until a Reclamation meeting with the Army Corps of Engineers took place in November, 1949, at which it was agreed to investigate a joint conservation and flood control project for the basin was the Santa Maria Project provided with the impetus it needed to be built. Perhaps now, with the help of two federal water resource managers, the success predicted by early travelers for the beautiful, wide, sea coastal plain would be assured long into the future. The Santa Maria Project took shape in its namesake river basin - the Santa Maria, in northern Santa Barbara County, sixty miles northwest of the city of Santa Barbara and 130 miles from Los Angeles. The Santa Maria River Basin is comprised of 1,880 square miles, making it one of the larger coastal drainage basins in California. The Santa Maria watershed includes the north half of Santa Barbara County (with Santa Barbara`s Cachuma Project taking up the southern half) and very small portions of San Luis Obispo, Ventura, and Kern Counties. The Santa Maria River is formed by the confluence of the Cuyama and Sisquoc Rivers, which meet about twenty miles from the coast, flowing westward to the Pacific as the Santa Maria. The largest town in the area served by the project is Santa Maria, which lies on the river about eleven miles inland and is the second most populated city in Santa Barbara County.(1) The annual average flow of the Cuyama River, which is dammed about six miles above its confluence with the Sisquoc is 40,400 acre-feet (a-f). The river is dry much of the year, with a sizeable stream flow occurring only following the storms of the wet season. Like the project area of its neighboring Reclamation project in southern Santa Barbara County, Cachuma, Santa Maria is characterized by a brief rainy season in the winter months and a long dry season the remainder of the year. The basin averages fourteen inches of rain per year, though it, too, has exhibited wildly fluctuating amounts of precipitation, from a low of four inches to a high of thirty.(2) The primary feature of the Santa Maria Project is the Twitchell Dam (formerly named the Vaquero Dam; it was renamed in 1957 to honor T.A. `Cap` Twitchell, a long-time, local proponent of the project and head of the local water district). The dam is located on the Cuyama River about six miles upstream from that river`s junction with the Sisquoc and where the river becomes the Santa Maria. Spaniards observed forty-nine Chumash Indian villages in the Santa Maria area when they first visited the area briefly in the late 1700`s. By the time the basin was settled in the mid-1800`s, the natives were largely gone. Evidence still exists of the Chumash and their predecessors in the valley in the form of petrographs appearing on rock formations in the Sisquoc backcountry east of Santa Maria and Twitchell Dam, and of shell mounds located near the coast. The Chumash subsisted largely on fish and shellfish from the sea (a steelhead salmon run took place on the Santa Maria River until the early 1900`s) and game taken from the mountain regions.(3) The first visit to the Santa Maria area by Europeans occurred in 1776 when the Juan Bautista De Anza expedition camped in the valley, recognizing it for its fertile plain and agricultural possibilities. Others also saw the potential in the broad basin. Duflot de Mofras, traveling on a Spanish ship in the early 1800`s, described his travels along the Pacific coast and referred to Santa Maria. `The eighteen leagues that separate the Mission de la Concepcion (near Lompoc) from that of San Luis Obispo consist primarily of an extensive plain called La Larga (a name used by early explorers for the Santa Maria Basin). This, watered by the San Geraldo River, is noted for its fine grazing.`(4) Settlement of the region did not take place until 1840, though, when the Mexican government issued the 30,000 acre, Rancho Guadalupe land grant to Teodoro Orrellanes and Diego Olivera. They raised cattle on their lands, as did the others that followed until the disastrous drought of the 1860`s killed most of the livestock. After this, the American farmers of the valley switched their agriculture activity to growing grain and fruit.(5) The San Francisco Journal of Commerce extolled the agricultural virtues of the area when it stated in April, 1887, `There are unmistakeable evidences that the Santa Maria Valley was in the remote past an extensive bay, extending inland from the ocean, and the soil shows a richness for a depth of 75 feet in many places that cannot be surpassed in any other section of the country.`(6) Heeding this call was the Union Sugar Company of San Francisco, precursor of agribusiness in the Santa Maria Valley. It appeared on the scene in 1897 and had the means to search out and then construct the first irrigation system in the basin. They were followed in 1905 by a private irrigation venture organized for the purpose of taking water from the Sisquoc River and transporting it to Santa Maria by gravity canal. However, when a flood destroyed this operation in 1909, no efforts were made to reconstruct it.(7) Agriculture in the area had come to rely on the huge aquifer residents had discovered underlaying nearly the entire valley. The presence of this underground water, in addition to the aforementioned floods, explain Santa Maria`s water history - past, present, and future. The Santa Maria Valley consists mostly of a broad, alluvial floodplain area known as the Santa Maria Plain. Bordering the plain on the north and south are elevated terraces or mesas, with the Sierra Madre Mountains rising to the east. As the observant Duflot de Motras related in the eighteenth century, the plain was, in fact, not too long ago part of the Pacific, as is evident in the area`s hydrogeology. When the land receded and lifted, the alluvium stayed put. Streams running down from the mountains such as the Sisquoc and Cuyama replenished the vacated space with freshwater, creating the water source that Santa Maria`s farmers would tap for years to come.(8) Hydrogeologists studying this source believe the main water body is as much as 8 miles wide and underlies approximately 110,000 acres of the basin. The total freshwater volume is estimated to be 10 million a-f, but only a small portion (approximately 50,000 a-f/yr) of the total volume can be withdrawn for use without exceeding the annual average yield. Exceeding that amount could allow sea water to degrade the freshwater source (9) By 1950 some deep wells which had formerly produced 1,000 gallons per minute (GPM) from the principal water-bearing alluvium were reduced to 250 GPM. Farmers in those areas were forced either to pump elsewhere, to pump deeper, or to pump more often to make up for the less efficient production, all expensive options. Without a source of aquifer replenishment, increasingly expensive pumping would become even more widespread in the valley.(10) The conspicuous topography of the broad, alluvial Santa Maria Plain, together with the strong Pacific storms that deluge the area from time to time, conspired to make this valley, in particular, one fraught with flooding problems. Historical accounts of floods dating back to 1811 show twenty-five flood events sufficient to cause widespread damage.(11) To make matters worse, recent siltation of the Santa Maria River has increasingly clogged the channel for storm runoff, making the likelihood of future floods very real. The annual average value of property damage caused by floods in the Santa Maria Valley prior to the Santa Maria Project was $710,000 (1950).(12) Despite the growing need to confront these recurrent issues, this roughly thirty-five mile long, three- to ten-mile wide basin known as the `Valley of Gardens` continued to make itself known for its agricultural production, particularly with regard to its vegetable and flower seed crops. With the area`s fortuitous climate allowing for an annual growing season of over 275 days, and, hence, two to three harvests per year - and a sizeable local water source - the area had become one of the top agricultural producers in the region. The first discussions concerning the valley`s water needs were prompted in 1924 in response to lowering underground water levels. The Santa Maria Chamber of Commerce initiated the first comprehensive survey of the Cuyama River watershed. From this study, directed by irrigation engineer Martin C. Polk of Chico, California, the Chamber of Commerce concluded that the cost of a viable, local water project was prohibitive at that point in time.(13) A subsequent hydrologic report by J.B. Lippincott submitted to Santa Barbara County in 1931 discussed, for the first time, the feasibilty of storage reservoirs on the Cuyama and Sisquoc Rivers, but the report was shelved until after World War II.(14) In 1937, the water issue became pressing enough to put the creation of a local water conservation district to a vote. When a flood struck three days before the election, ripping out highways, bridges, and powerlines, and drowning cattle, any opposition was squelched and the pro-district side won easily. T.A. `Cap` Twitchell, the son of a Santa Maria pioneer, a strong proponent of water development in the valley, and instigator of Santa Barbara`s Cachuma Project, was voted to head the Santa Maria Valley Water Conservation District (SMVWCD).(15) Reclamation`s first activity in Santa Maria was a land classification survey in 1942. This was followed in 1946 by a report on the Santa Maria Basin as part of a Santa Barbara County-wide analysis of its water resources. Although this activity resulted in the eventual construction of Santa Barbara`s Cachuma Project, Santa Maria`s needs were not, at that moment, deemed quite as critical as were Santa Barbara`s, so their report was shelved. Not Reclamation and the Corps of Engineers met in Los Angeles, in November, 1949, was impetus given for construction of the Santa Maria Project. At that conference the two parties, together with the SMVWCD, agreed to investigate a joint conservation and flood-control project for the basin.(16) The reconnaissance geologic survey made of the Santa Maria Basin during Reclamation`s investigation included profiling 68 miles of river and 14 damsites, the seven most promising of which were studied in more detail. Three foundation explorations were made before the site of Twitchell Dam was finally selected. The resultant `Report on Santa Maria Project, Southern Pacific Basin, California,` formed the basis of ultimate authorization for the project on September 3, 1954.(17) In Santa Maria, the directors of the SMVWCD decided to form the `Committee of 35,` a unique advisory group comprised of a cross-section of Santa Maria citizens selected to help the directors formulate a fair project repayment plan. The committee voted unanimously in favor of calling an election on a special ad valorem assessment on lands to be taxed to provide for repayment. The directors then placed the $13.96 million Vaquero Project (its original name) repayment contract with the SMVWCD on the ballot for voter approval. On January 31, 1956, the Santa Maria Project was given the official go-ahead.(18) The objectives of the Santa Maria Project were to recharge the critically-depleted groundwater reservoir underlying the basin and to eliminate the future flood threat to valley lands. There would be no surface water deliveries from the new reservoir since what water was captured would typically be immediately released to replenish underground supplies. Since the reservoir would be empty most of the year, Reclamation made no plans for recreation. Being a conservation and flood-control project, both Reclamation and the Army Corps of Engineers participated. The percentage breakdown of total costs were 82.25% to irrigation and, hence, Reclamation, and 17.75% to flood control and the Corps of Engineers. The planned 239,000 af capacity reservoir was slated to reserve 150,000 af for conservation purposes and 89,000 af for flood control. It was planned that a reservoir this size could reduce a potential 230,000 cfs, 400-year flood to one that becomes a less threatening 150,000 cu-ft-sec, and at the same time produce an average annual yield of 18,500 af of increased recharge to groundwater basins, overcoming a 14,000 af overdraft and providing for municipal and industrial needs as well.(19) Operation of the conservation side of the project would be such that dam operators would attempt to most closely replicate the stream channel`s percolation rate, releasing flood water stored in the conservation space of the reservoir at a rate that was determined to be approximately 300 cfs. Anything less would be absorbed by the river channel and fail to make it to deposits tapped downstream; too large a flow would waste to the sea.(20) The Corps` flood control design consisted of a series of levees and channel improvements along the Santa Maria River to protect the city and its valley lands. One levee was raised on the south bank extending from Fugler Point (the confluence of the Cuyama and Sisquoc Rivers) westward for seventeen miles, and another on the opposite bank stretching five miles downstream. Bradley Canyon, a smaller side canyon and notoriously flood-prone, was outfitted with a 1.9-mile levee to divert its floodwaters into the newly-reinforced Santa Maria River. The Corps` channel clearing project on the Santa Maria from Fugler Point to the sea was designed to increase the river`s capacity, which had been reduced by heavy sedimentation. The Corps` plan would protect Santa Maria from a 150,000 cu-ft-sec flood peak, assuming partial capture (89,000 ac-ft) by Twitchell Dam.(21) The contract for construction of the Vaquero Dam was awarded to Mittry Construction of Los Angeles for $6.17 million. They began work on the structure in July, 1956. The outlet works were constructed early on in order to divert Cuyama River flowage, allowing Mittry to place the embankment the entire length of the dam. The outlet works consist of: an inlet structure, 350-feet of concrete conduit 15-feet in diameter; 322-feet of concrete-lined circular tunnel 15-feet in diameter; 422-feet of concrete-lined horseshoe tunnel 19-feet by 17-feet; and a chute 30-feet long with 56-foot high vertical walls. A vertical shaft bisects the outlet works tunnel at the end of the circular section. This vertical shaft is for the placement, operation, and maintenance of four 4-foot by 7-foot control gates for the outlet works. The control gates provided measured releases to coincide with the river bed`s natural percolation rate. Mittry also constructed a spillway for protection of the dam to allow uncontrolled spillage when the reservoir`s water surface elevation reaches 651.5 feet (the crest of the dam is at 692). The spillway is a steep, inclined, concrete-lined shaft bored through the mountain-side to the right of the dam`s right abutment. The shaft connects with a concrete-lined tunnel 23-feet in diameter and 695-feet long, with a 125-foot concrete chute at the end. This allows spilled water to flow into an adjacent canyon which joins the Cuyama River downstream from the dam. The dam itself is 218 feet high with a crest length of 1804 feet. It is an earthfill structure containing 5.8 million cubic yards of material.(22) The Vaquero Dam`s name was changed to Twitchell during ceremonies on September 20, 1957, in order to honor the recently-deceased, former director of the SMVWCD, T.A. `Cap` Twitchell. The dam was finished on June 28, 1958, at a final cost of $12.04 million, a remarkable 30 percent under the originally authorized figure of $16.9 million. This was due primarily to Reclamation being able to procure flowage easements on lands needed for the reservoir, instead of having to purchase the land outright, reducing the project`s costs substantially. Since the maximum reservoir water level would be rarely if ever hit, nearby landowners were allowed by their easements to graze their cattle inside the reservoir area.(23) Reclamation transferred operation of the Twitchell Dam to the SBCWA and physical operation of it to the SMVWCD on June 1, 1959.
Plan
Twitchell Dam is on the Cuyama River about 6 miles upstream from its junction with the Sisquoc River. The multiple-purpose Twitchell Reservoir has a total capacity of 224,300 acre-feet. It stores floodwaters of the Cuyama River, which are released as needed to recharge the ground-water basins to prevent salt water intrusion. The objective of the project is to release regulated water from storage as quickly as it can be percolated into the Santa Maria Valley ground-water basin. Therefore, Twitchell Reservoir is empty much of the time, and recreation and fishing facilities are not included in the project. Twitchell Dam is an earthfill structure, has a structural height of 241 feet, of which 216 feet are above streambed, a crest length of 1,804 feet, and contains approximately 5,833,000 cubic yards of material. The dam regulates flows along the lower reaches of the Cuyama River and impounds surplus flows for release in the dry months to help recharge the ground-water reservoir underlying the Santa Maria Valley, thus minimizing water waste. After construction, Reclamation transferred operations to the Santa Barbara County Water Agency. The Santa Maria Valley Water Conservation District physically operates the reservoir.
Contact
Contact
Title: Area Office ManagerOrganization: South-Central California Area Office
Address: 1243 "N" Street
City: Fresno, CA 93721-1813
Phone: 559-487-5116
Contact
Title: Public Affairs OfficerOrganization: Mid-Pacific Regional Office
Address: 2800 Cottage Way E-1705
City: Sacramento, CA 95825-1898
Fax: 916-978-5114
Phone: 916-978-5100
Contact
Title: Public Affairs OfficerOrganization: Commissioner`s Office
Address: 1849 C Street NW
City: Washington, DC 20240
Fax: 202-513-0575
Phone: 202-513-0305
Contact
Organization: Santa Maria Valley River Water Conservation DistrictAddress: PO Box 364
City: Santa Maria, CA 93456
Fax: 805-739-0763
Phone: 805-925-5212
