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The Ventura River Project, in southern California is on the coast about 60 miles northwest of Los Angeles. The 90,000-acre project area is fan-shaped--the main Ventura River Valley runs north-south from the Topatopa Mountains down to the Pacific and several side valleys drained by tributaries of the Ventura River funnel into the main basin from the east and west. An additional strip of project land (Rincon) lies parallel with and outside of the basin along the Pacific coast northwest of the city of Ventura. Authorized in 1956, the Ventura River Project was the third and last of three large-scale Federal water projects in the region. These "seacoast projects"capture the seasonal floodwaters that would otherwise "waste to the sea." Further south and east down the coast from the prior-constructed Cachuma and Santa Maria Projects. Only 30 percent of the rugged and mountainous project area is considered developable. The district is highly urbanized along the coast. The project furnishes an irrigation water supply to about 15,200 irrigable acres of land, and municipal and industrial water to approximately 40,000 users in urban and suburban areas within the Casitas Municipal Water District (formerly the Ventura River Municipal Water District). The Ventura River and its tributaries are the main water sources for the project. The Ventura River bisects the lower, southern portion of this area, flowing for about sixteen miles from its formation at the confluence of Matilija Creek and the North Fork of Matilija Creek to the Pacific Ocean. The river's coastal inlet lies at the western edge of the city of Ventura, the largest town in the project area. Its two principal tributaries are San Antonio Creek from the east and Coyote Creek from the west. The annual average flow of the Ventura River is 13,600 acre-feet. It is a highly fluctuating, intermittent stream, running usually only in the winter month's "wet season." The area averages 14 inches of precipitation per year, with ranges varying from 5 to 40 inches. The Ventura River Project comprises a storage reservoir on Coyote Creek, a diversion dam on the Ventura River, a canal to carry water from the diversion dam to the reservoir, and a high-pressure pipeline distribution system. The distribution system has pumping plants and balancing reservoirs to distribute the water from Lake Casitas to the various areas within the project for irrigation, municipal, and industrial uses. The project also uses water from Matilija Dam, built by Ventura County and placed in operation in 1948. The main features of the Ventura River Project are:
Completed in 1959, Casitas Dam is the key component of the Ventura River Project. Casitas Dam is located on Coyote Creek about 2 miles above the junction of the creek and the Ventura River. The dam is a 334-foot-high earthfill structure that has a crest length of 2,000 feet and contains a total of 9,310,000 cubic yards of material. The dam's spillway, on the left abutment, is founded on rock along its entire length. It consists of a concrete-lined inlet channel, an uncontrolled overflow concrete crest, and a concrete spillway chute and stilling basin. An 800-foot-long sloping, multi-level intake structure on the upstream face of the dam is connected to a 1,800-foot long outlet tunnel bored through the left abutment of the dam. The outlet tunnel is a 7-foot-diameter circular section for about one-half its length, the circular section terminating at a main valve chamber. From this point, the tunnel is an 8-foot horseshoe section and the water flows through a 51-inch steel pipe. Casitas' outlet works which distribute water to District subareas through over 34 miles of pressure pipeline. It is a reinforced-concrete structure which rests on the sloping upstream face of the dam and encases a 48-inch steel outlet pipe which is fitted with nine hydraulically operated slide gates at uniform intervals between minimum and maximum reservoir water levels. The outlet work has a capacity of 570 cubic feet per second. A catwalk was also constructed alongside the pipe to permit access to the main valve chamber. Each outlet gate is fitted with a semi-cylindrical screen which can be removed and taken to a washrack above high water through the operation of a system of tracks, cables, and pickup carriage. The hydraulic slide gates are operated by means of a control house located at the top of the dam. Lake Casitas regulates flows along the lower reaches of Coyote Creek and stores surplus water for irrigation and municipal purposes. It has an active capacity of 251,000 acre-feet and a storage capacity of 254,000 acre-feet. Lake Casitas provides irrigation, municipal and industrial water to urban and suburban areas with the Casitas Municipal Water District. Robles Diversion Dam is located on the Ventura River about 1.5 miles downstream from the confluence of Matilija Creek and North Fork Matilija Creek. The dam has a height of 24 feet and a crest length of 598 feet. The structure is rockfilled with a timber cutoff wall and a rolled earth core. The dam diverts water into the headworks of the Robles-Casitas Canal. The dam's sluiceway has a capacity of 10,000 cubic feet per second and is controlled by four radial gates. Water entering the diversion canal headworks at the dam is controlled by three radial gates. The cutoff wall needed to be repaired twice after heavy storms, once in 1969 and once in 1979. Robles-Casitas Canal Robles-Casitas Canal carries water from Robles Diversion Dam to Lake Casitas. The canal is about 4.5 miles long with a capacity of 500 cubic feet per second. There are 4.5 miles of concrete canal and 0.9 mile of 78-inch reinforced concrete pipe, called the Robles-Casitas Diversion Conduit. The open canal has a width at the top of 27 feet, sloping to a bottom width of 7 feet. Conveyance System The Ventura River Project's conveyance system includes miles of pressure pipeline, five pumping plants, since much of the service area lies at a higher elevation than Casitas Reservoir, six steel tank balancing reservoirs for peak and emergency storage, and chlorination stations to disinfect the water. The main pipeline is a pressure-pipe system nearly 34 miles long that consists of reinforced concrete pipe and mortar-lined steel pipe ranging from 12 to 54 inches. The main conduit starts at Casitas Dam with a capacity of 121 cubic feet per second. After crossing the Ventura River, the conduit branches to serve the lower area to the west, including the city of Ventura, and the upper area to the north and east of Lake Casitas. The main conduit for the west coastal area has a capacity of 9.6 cubic feet per second at the dam; it passes through a pumping plant and traverses 9.7 miles in a westerly direction over Casitas Pass to the Rincon Balancing Reservoir near the coast. The system connects with an existing pipeline from Matilija Reservoir. One 23.3-mile section of the main conduit extends from Casitas Dam to the Upper Ojai Valley and has an initial capacity of 135 cu-ft-sec. After crossing the Ventura River, it branches to serve the lower portions of the service area, including the City of Ventura and the higher elevation areas to the east and north of Casitas Reservoir. The 9.6 cubic-feet-per-second capacity Rincon pipeline (ranging from 16 to 21 inches in diameter) serves the west coastal area of the project. It starts at the dam where a pumping plant lifts the water 900 feet over Casitas Pass to the Rincon Balancing Reservoir near the coast, a distance of 9.7 miles. Pumping Plants Five pumping plants, Ventura Avenue No. 1 and No. 2, Ojai Valley, Upper Ojai, and Rincon, lift water from the storage level elevation in Lake Casitas to the elevations at the points of delivery. Balancing Reservoirs, Chlorination Stations, and Distribution System Six balancing reservoirs, Oak View, Villanova, Ojai East, Upper Ojai, Rincon Control, and Rincon Balancing, are filled from the main conduit during the off-peak hours and are used to help supply the full requirement of water during peak hours and as a carryover supply in case of an emergency. Five chlorination stations are provided, two downstream from the outlet of Lake Casitas, two downstream from the outlet of Matilija Dam, and one between the Rincon Pumping Plant and Rincon Control Reservoir. These stations are operated for the dual purpose of preventing algal growth in the pipelines to maintain their capacity for delivering water, and assuring the safety of the supply for domestic purposes. The Casitas Municipal Water District constructed and operates the distribution system within the project subareas. Operating agency Casitas Dam is owned by the United States, however, the water rights and water stored in Casitas Reservoir are owned by the Casitas Municipal Water District. Casitas Municipal Water District operates the project. History The coastal Chumash Indians lived on fish and shellfish from the sea and game from the backcountry. The Ventura River Basin was visited in 1542 by the Spanish navigators who landed at Ventura Harbor. Agriculture did not become established in the area until about 1782, when the Mission Fathers dedicated San Buenaventura. During the mission days, agricultural activities were devoted to raising crops and livestock to supply the needs of surrounding settlements. Water was diverted from Ventura River near the mouth of Canada Larga. An old, massive-walled settling tank that distributed river water to the mission is still intact today. During Mexican rule, prior to the middle of the 19th century, the land was divided into large grants that were subdivided later and sold to settlers. By 1900, more intensive cropping practices had replaced most of the earlier grain farming, and there was a gradual reduction in the size of farms. Production of apples, apricots, and peaches was initiated at an early date. Citrus fruits were successfully introduced into the Ojai and Ventura River Valleys; commercial planting started in the early 1900's. Development of urban communities and population growth within the Ventura River Basin has been rapid, particularly since 1920. Groundwater basins and stream flows provided pre-project water for agriculture and municipalities. The City of Ventura also had three wells alon gthe ocean beach for back-ups in a dry year. However, saltwater encroachment threatened these wells. Investigations Future economic growth of the area was dependent upon obtaining an additional dependable water supply. The need for more water had been recognized for many years, and investigations of the project area had been made by several organizations. Ojai Valley investigated potential solutions to the water supply problem in 1925, and Ventura investigated in 1934, but nothing came of either investigation. In 1953, the Ventura River Municipal Water District (now the Casitas Municipal Water District) formed. They worked with Reclamation to initiate water resource feasilibity studies on a match-fund basis. The resulting feasibility report dated December 1954, House Document 222, 84th Congress, 1st session was used as a basis for authorization of the project. Authorization The project was authorized by act of the Congress (Public Law 423, 84th Cong., 2d session) approved March 1, 1956. Construction Construction of Casitas Dam began three months later in July 1956 and was completed in March 1959; Robles Diversion Dam and five pumping plants were completed in 1958; other distribution works were started in 1957 and completed in 1959. The Ventura River Municipal Water District advanced funds to the Bureau of Reclamation for investigations and design of the proposed Ventura Project. This permitted almost immediate issuance of specifications and an early start on construction as soon as authorization was given. Recent Developments The ever-present problem of earthquakes was addressed in the early 1980's when a SEED Report (Safety and Evaluation of Existing Dams) on Casitas Dam classified it with a "Poor" grade because of the potential for liquefaction of the dam's foundation during a high magnitude earthquake which could cause damage to the slope intake structure. The problem was mitigated when computerized piezometers placed in the dam embankment recorded satisfactorily-low levels of seepage. Consequently, Casitas Dam's safety classification was upgraded to safe status. In 1999, Reclamation started a two year effort to upgrade Casitas Dam to current earthquake safety standards as part of an ongoing agency-wide modernization effort to enable Casitas Dam to withstand a magnitude 7 earthquake. The work will strengthen the toe of the dam and construct an earthen berm to widen and buttress the dam. The Casitas Dam information network has more information. Interim actions have reduced the overall risk to the public. A system of wells dewatered the weakest downstream foundation materials and an above ground system drained the spillway stilling basin. The interim project reduces the buildup of foundation pore-pressure during earthquakes, thus reducing the potential for liquefaction and resulting deformation of the downstream slope of the embankment until a long-term risk reduction project is completed. A summary of the Environmental Assessment was released Reclamation also installed eight emergency sirens along Coyote Creek and the Ventura River, would be activated in the unlikely event of imminent flooding below Casitas Dam. Irrigation The principal products of the project area are citrus and other fruits. In addition, avacadoes, walnuts, and berries contribute substantially to the agricultural produce of the area. The project supplies water to about 7,000 acres of agricultural lands. Municipal and Industrial The project serves 40,000 municipal customers. Recreation Lake Casitas offers fishing, boating, camping, and picnicking activities. The Casitas Municipal Water District manages the Lake Casitas recreation area. In 1980, over 1.5 million people visited Casitas. In 1984, Lake Casitas hosted rowing events for the Los Angeles Olympics.. |
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