Delta-Mendota Canal

Delta-Mendota Canal
Name	Delta-Mendota Canal
Country	United States
State	California
Length	117 mi (188 km)
Owner	United States Bureau of Reclamation
Operator	United States Bureau of Reclamation
Date completed	1951–1963
Start point	Central Valley Project Delta Pumping Plant
End point	Mendota Pool

Delta-Mendota Canal The Delta-Mendota Canal is a major water conveyance in California's Central Valley, delivering water from the Sacramento–San Joaquin River Delta to agricultural, municipal, and environmental users in the San Joaquin Valley, connecting with facilities of the Central Valley Project, the State Water Project, and regional irrigation districts. It serves as a link between the Friant Dam-affected flows, the Mendota Pool, and export facilities near the C.W. "Bill" Jones Pumping Plant and integrates with aqueducts, reservoirs, and groundwater recharge systems operated by federal, state, and local agencies such as the United States Bureau of Reclamation, the California Department of Water Resources, and the San Joaquin River Exchange Contractors.

Overview and Purpose

The canal was conceived to augment water deliveries to Fresno County, Madera County, Merced County, Stanislaus County, and Madera Irrigation District lands, providing conveyance for project water from the Clifton Court Forebay and the Delta Cross Channel toward the Mendota Pool and the San Joaquin River diversion points. It supports irrigation for crops in the San Joaquin Valley such as cotton, almonds, tomatoes, and grapes grown in regions like the Westlands Water District and serves municipal suppliers including City of Tracy and City of Modesto. The canal complements infrastructure like the California Aqueduct, the Friant-Kern Canal, and the Delta–Mendota Canal Pumping Plant to balance surface storage in reservoirs such as Shasta Lake, Lake Oroville, New Melones Reservoir, and San Luis Reservoir.

History and Construction

Legislation and planning for the canal were driven by proponents associated with the Reclamation Act era and later projects advocated by leaders in Congress from California, and engineered by the United States Bureau of Reclamation and contractors who also worked on the Central Valley Project and the State Water Project. Construction phases occurred from the early 1950s into the early 1960s, timed with development of San Luis Reservoir and the O'Neill Forebay to coordinate pumping operations at the C.W. Bill Jones Pumping Plant and the Delta Pumping Plant. Key figures and entities involved included engineers and administrators from the Bureau of Reclamation, elected officials from California's 12th congressional district and neighboring districts, and agricultural interests represented by groups like the Mendota Pool Board and the Friant Water Users Authority. The project followed precedent set by earlier federal works such as Shasta Dam and Folsom Dam and intersected with water law developments including cases before the California Supreme Court and discussions in the United States Congress over water rights and interstate water policy.

Route and Engineering Features

Beginning at the Clifton Court Forebay near the western edge of the Sacramento–San Joaquin River Delta, the canal extends roughly 117 miles southward, paralleling portions of Interstate 5 and passing near communities including Dutch Slough, Tracy, Los Banos, and Firebaugh before terminating at the Mendota Pool adjacent to the San Joaquin River near Fresno County. Major engineering elements include lined earthworks, concrete-lined sections, siphons, gated control structures, turnout facilities for districts such as the Westlands Water District and the Grassland Water District, and crossings under infrastructure like California State Route 152 and California State Route 33. Pumping stations, including the Delta Pumping Plant and integration with the O'Neill Pumping Plant, enable lifts measured in tens of feet to overcome gradient and operate with coordination among reservoirs such as San Luis Reservoir and Millerton Lake.

Operations and Water Management

Operational control is maintained by the United States Bureau of Reclamation with coordination from the California Department of Water Resources, local irrigation districts, and water contractors like the Semitropic Water Storage District and the Panoche Water District. The canal conveys project water, exchange water, and surplus flows from the Sacramento River via the Delta Cross Channel and the Clifton Court Forebay, supporting groundwater recharge projects in basins managed under the California Sustainable Groundwater Management Act and conjunctive use programs coordinated with agencies such as the Friant Water Authority and the California State Water Resources Control Board. Operations are influenced by regulatory regimes stemming from the Endangered Species Act listings for species like the delta smelt and winter-run Chinook salmon, decisions from the United States District Court for the Eastern District of California, and allocation determinations by the Federal Energy Regulatory Commission when hydropower interties exist.

Environmental and Ecological Impacts

The canal interacts with ecosystems of the Sacramento–San Joaquin River Delta, the San Joaquin River National Wildlife Refuge, and the Tule River watershed, affecting habitats for listed species such as delta smelt, Central Valley steelhead, and San Joaquin kit fox. Water exports and flow alterations have been central issues in litigation and policy debates involving groups like the Natural Resources Defense Council, the Sierra Club, agricultural stakeholders including the California Farm Bureau Federation, and municipalities such as City of Stockton. Mitigation and restoration efforts have included habitat restoration projects coordinated with the United States Fish and Wildlife Service, managed wetlands operated by the California Department of Fish and Wildlife, and adaptive management programs supported by research institutions like the University of California, Davis and the U.S. Geological Survey. Salinity intrusion, selenium mobilization from soils in the Kesterson Reservoir era, and impacts on Groundwater Basin quality have prompted monitoring by entities such as the Central Valley Regional Water Quality Control Board and measures under state initiatives like the California WaterFix debates.

Recreation and Public Access

Public access along the canal corridor is limited by safety and operational restrictions enforced by the United States Bureau of Reclamation and local districts, but nearby recreational opportunities include boating and fishing at San Luis Reservoir, wildlife viewing at the Grasslands Wildlife Management Area, and outdoor recreation in adjacent parks such as San Luis National Wildlife Refuge and state parks including Pacheco State Park. Communities along the route—Los Banos, Tracy, Fremont-adjacent areas, and Firebaugh—offer access points to recreation tied to reservoirs, trails, and hunting areas administered by agencies like the California Department of Parks and Recreation and the U.S. Fish and Wildlife Service.

Category:Canals in California Category:Central Valley Project Category:Infrastructure completed in 1963