The Lower San Joaquin River Feasibility Study (LSJRFS) aims to reduce the overall flood risk in the Stockton metropolitan area. A high risk of flooding from levee failure threatens the safety of people, property and critical infrastructure throughout the area.
The study area is located along the lower (northern) portion of the San Joaquin River system in California's Central Valley. The San Joaquin River originates on the western slope of the Sierra Nevada and emerges from the foothills at Friant Dam. The river flows west to the Central Valley, where it is joined by the Fresno, Chowchilla, Merced, Tuolumne, Stanislaus and Calaveras rivers and smaller tributaries as it flows north to the Sacramento-San Joaquin Delta.
Study and Project History:
This study was authorized by the Flood Control Act of 1944 and construction initiated in 1956 with various modifications made through the mid-1980’s. The Federally-constructed portion of the project consists of 100 miles of intermittent levees along the San Joaquin River downstream of the Merced River, as well as along Paradise Cut, Old River, Camp Slough, and the lower reaches of the Stanislaus and Tuolumne Rivers. The project also included construction of New Hogan Dam on the Calaveras River, New Melones Dam on the Stanislaus River, and Old Don Pedro Dam on the Tuolumne River. The Chowchilla and Eastside Bypasses were constructed by the State as part of the project. Project levees were designed and built to reduce flood risk in the downstream areas.
Over the 60-year period since those levees were constructed, their estimated level of performance has been reduced by changes in the hydrologic record, settlement, erosion, extensive sediment deposition, and establishment of vegetation between the levees. The project cannot be maintained as originally envisioned due to environmental constraints that did not exist when the project was authorized and constructed.