General

The Cachuma Project is one of three large-scale Federal water projects in the region, the other two are the Santa Maria and the Ventura Projects. These seacoast projects capture the seasonal floodwaters that would otherwise waste to the sea.

The Cachuma project provides supply water for the historically water deficient communities of the South Coast area, including the venerable, old Spanish mission city of Santa Barbara, its smaller, urban neighbors, and 38,000 acres of outlying agricultural lands. The project stores floodwaters of the nearby Santa Ynez River. This river basin`s runoff comes from precipitation in the rainy season, October to April. Consequently, trapping what rain fell was critical, especially during the inevitable dry cycles when users could rely only on the storage of past seasons` remaining surplus.

Construction of the project, which was authorized in 1948, began in 1950 and was completed in 1956. The rapid urban growth that has taken place since completion of the project is encroaching on large acreages of previously irrigated and non-irrigated arable lands, especially in the Goleta Valley.

History

The coast of the Santa Barbara region was first visited in 1542 by navigators under the Spanish Crown; however, no attempt was made to settle the land until 1782 when the Presidio of Santa Barbara was founded at the present location of the city of Santa Barbara. The Santa Barbara Mission was built in 1786. By 1802, the mission was the center of extensive grain fields and fruit orchards and the home range for great herds of livestock. By 1846, cattle raising was the most important industry.

Following the decline of the cattle industry after droughts in the 1860`s, several of the large ranches were subdivided and sold to eastern immigrants. This started the gradual transition from ranching to intensive farming of smaller acreages. Dry farming of wheat, barley, corn, hay, beans, peas, potatoes, garden vegetables, and fruit expanded rapidly. At the turn of the century irrigation began to develop, first for growing sugar beets and alfalfa, then for vegetables and other crops. As early as 1903 the Santa Ynez River watershed was recognized as the only feasible long-term source of a dependable water supply for the increasing population of the South Coast area.

The first diversion of water from the Santa Ynez river basin to Santa Barbara took place in 1920 with the construction of the Gibraltar Dam and Reservoir and Mission Tunnel by the City of Santa Barbara. Before this, the city of Santa Barbara had used local streams and tunnels in the Santa Ynez Mountains and ground water. In 1930, Montecito County Water District, to the east of Santa Barbara, completed construction of Juncal Dam upstream from Gibraltar Dam on the Santa Ynez River. As the population of the South Coast area continued to increase, its water problems compounded. By the 1940`s it was evident that the underground springs were being pumped faster than the rate of natural replenishment. If this continued, it was estimated that 30% of the presently irrigated areas would have to revert to dry farming. In addition, post-war population growth caused the City of Santa Barbara to exceed by at least 1/3 planners` safe annual yield of all its sources. The area simply could not keep pace with consumption. The area resorted to water rationing and fines for overuse.

Construction

Construction of Cachuma Dam and the South Coast Conduit was started in 1950 and completed in 1953.

The four regulating reservoirs, Glen Anne, Lauro, Ortega and Carpinteria, were built during 1951-1954. Distribution systems for the Goleta, Carpinteria, and Summerland County Water Districts were constructed by Reclamation during 1952-1956. The region’s aridity causes Cachuma to lose an estimated 16,000 acre-feet of water to evaporation annually.
The same arid, barren landscape that was so susceptible to natural disaster, also lent itself to another problem causing particular frustration among dam managers in the region - that of sedimentation.

The chaparral flora, rainstorms, landslides, and wildfires all resulted in prodigious amounts of silt washing into Lake Cachuma and backing up behind Bradbury Dam. Managers have tried a series of mitigating measures, none of which has made much of a dent in silt buildup.

Plan

No text for this section

Overview

Bradbury Dam stores floodwaters of the Santa Ynez River which would otherwise waste to the ocean. Water is diverted from the reservoir through the Tecolote Tunnel to the south coast area. From the tunnel outlet the water is carried through the South Coast Conduit. Lateral systems distribute water from the conduit to croplands of the Goleta, Montecito, Summerland, and Carpinteria Water Districts, and to municipal users in the city of Santa Barbara.

Bradbury Dam was originally named the Cachuma Dam. The name was changed in 1971 to honor local water proponent Brad Bradbury. It is located on the Santa Ynez River approximately 25 miles northwest of Santa Barbara. It is a zoned earthfill structure, containing 6,695,000 cubic yards of material. It is 279 feet high from the bottom of the cutoff trench to the top of the dam and 206 feet above the streambed. The spillway section is concrete-lined, with four 50x34 foot radial gates and has a capacity of 161,000 cubic feet per second. Lake Cachuma has a capacity of 193,300 acre-feet. The lake covers 3250 acres when full and has a 42-mile shoreline.

Tecolote Tunnel extends 6.4 miles through the, Santa Ynez Mountains from Lake Cachuma to the headworks of the South Coast Conduit. The horseshoe-shaped tunnel is 7 feet in diameter and has a capacity of 100 cubic feet per second. The concrete lined tunnel goes beneath the dam and contains the controlled outlet works. These consist of the concrete-lined tunnel through which two 30-inch, hollow-jet valves and one 10-inch butterfly valve pass non-flood flows of the river to downstream users. This special outlet works apparatus allowed for the protection and recognition of downstream water rights by continuing the uninterrupted delivery of Santa Ynez water.

The South Coast Conduit conveys Santa Ynez River water from the Tecolote Tunnel through the South Coast water districts. It is a high-pressure concrete pipeline. The conduit extends 24 miles from the Tecolote Tunnel outlet across the steep canyons, rolling hills, and highly-developed residential and estate areas of the South Coast. It stretches to the Carpinteria Regulating Reservoir in the heart of the Carpinteria County Water District’s service area. The conduit includes four regulating reservoirs.

The Lauro (Santa Barbara), Ortega (Summerland), and Carpinteria Regulating Reservoirs were constructed along and integrated with the South Coast Conduit to gravitate or float along the line. Automatic pressure valves controlled the reservoirs` storage so that they supplied additional water during periods of peak demand.

The fourth regulating reservoir, the Glen Anne, was located below the outlet portal of the Tecolote Tunnel and had served as overflow storage for the conduit, receiving its water supply by gravity from an outlet near the head of the South Coast Conduit. On August 19, 2002, Glen Anne Reservoir was placed under permanent restriction due to seismic-related risks. The reservoir is currently maintained but no longer operated.

The last phase of the Cachuma Project included three separate, localized water distribution systems constructed by Reclamation for direct delivery to Goleta, Carpinteria, and Summerland County Water District consumers. In these primarily agricultural areas, the landscape called for small pumping plants to serve lateral pipelines. In Carpinteria, a 50,000-gallon elevated water tank ensured delivery to more difficult-to-reach areas. These systems were all operable by early 1956. Each individual district for which a distribution system was constructed is responsible for its operation and maintenance. Reclamation operates Bradbury Dam. Member units acting through the Cachuma Operation and Maintenance Board operate the rest of this project.

Other

No text for this section