Santa Ynez River - River Modifications

River Modifications

There are three reservoirs on the river, the largest of which is Lake Cachuma, with a capacity of 205,000 acre feet (253,000,000 m3). Bradbury Dam, which forms the lake, was built by the U.S. Bureau of Reclamation. Water from Lake Cachuma is diverted into the Tecolote Tunnel, which passes south under the Santa Ynez Mountains. The tunnel supplies water to the city of Santa Barbara (which uses it for drinking water), the Goleta Water District, the Carpinteria Valley Water District, and the Montecito Water District. Water from Lake Cachuma is released into the Santa Ynez River below Bradbury Dam in order to satisfy downstream water rights.

The other two reservoirs are Gibraltar Reservoir, impounded by Gibraltar Dam, and Jameson Lake, impounded by Juncal Dam. Gibraltar Reservoir supplies water to the City of Santa Barbara via the Santa Barbara Water Tunnel under the Santa Ynez Mountains. Jameson Lake supplies water to the Montecito Water District via another tunnel under the Santa Ynez Mountains. In 2004 the diversions amounted to 3,130 acre feet (3,860,000 m3) from Gibraltar Reservoir, and 1,730 acre feet (2,130,000 m3) from Jameson Lake.

A 2010 report on the restoration potential of the Santa Ynez River estuary, found "Over the last 150 years human activities, especially dam construction, have significantly affected river flows in the entire watershed. The most important changes to wetland habitats and ecologic processes have resulted from changed river inflows and sediment loads from the watershed combined with changing hydraulic and geomorphic effects from bridge causeways. These process changes have led to alteration of sedimentation and erosion patterns and converted wetland habitats to upland. Upstream dam construction now controls 47% of the watershed’s annual runoff, has reduced the frequency and duration of lagoon breaching as well as the magnitude and frequency of flood events that have the most important role in sustaining and renewing a mosaic of wetland and estuarine habitats within the estuary and lower river."