Lower San Joaquin River Project

Reducing flood risk for communities and strengthening economic resilience - the Lower San Joaquin River Project protects more than 235,000 residents and critical infrastructure in Stockton.

Project Overview

Problem and Need
The Lower San Joaquin River Project addresses significant flood risks in north and central Stockton, California. Historical flood events in 1955, 1958, and 1997 have underscored the area's vulnerability. The project aims to protect:

Over 71,000 acres of mixed-use land.
An estimated 264,000 residents.
Approximately $21 billion in property value.

Key benefits include:

An estimated 83% reduction in expected annual property damages.
Enhanced security for 486 critical infrastructure sites, including 23 essential to life-safety.
Support for maintaining FEMA levee certification, potentially reducing National Flood Insurance Program costs for the community.

Non-structural measures complement the physical improvements, focusing on comprehensive flood warning systems, emergency evacuation planning, and floodplain management.

Funding and Partnerships

Estimated Total Project Cost: Approximately $2.03 billion (as of 2022).
Estimated Total Annual Benefits: $345 million, with net annual benefits of $295.7 million.
Cost Sharing: 65% Federal / 35% Non-Federal.
Lead Agency: U.S. Army Corps of Engineers, Sacramento District.
Partner Agencies: Central Valley Flood Protection Board, California Department of Water Resources, San Joaquin Area Flood Control Agency

Current Status
The project encompasses 23 miles of levee improvements and two closure structures at Fourteenmile Slough and Smith Canal. The construction is phased as follows:

Phase 1: Tenmile Slough (TS30L)

Location: Western Stockton along Tenmile Slough.
Length: Approximately 5,900 feet.
Construction Start: Spring 2025.
Scope: Installation of a cut-off wall, levee reshaping, and waterside erosion protection.

Subsequent Phases:
The remaining phases (Phases A through F) will address additional levee segments throughout north and central Stockton. Construction for these phases is scheduled to commence between 2028 and 2035, with overall project completion anticipated by 2037. For detailed maps and descriptions of each phase, visit: Maps & Features section.

Map & Project Features

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Smith Canal

Construction on the Smith Canal Gate Project began in 2020, as part of the Lower San Joaquin River Project. Constructed by SJAFCA, partnered with Reclamation Districts 1614 and 828, the project consists of a floodwall along the San Joaquin River from Dad’s Point to the eastern boundary of the Stockton Golf & Country Club, tying into the existing levee. The floodwall features a gate for tidal exchange and boat access to Smith Canal, and will remain open unless there is a flood event. More information can be found on the SJAFCA Smith Canal webpage.

TS30L – Tenmile Slough

Type of Work: Levee fix in place with the addition of a cut-off wall, geometry reshaping, and waterside erosion protection.

Location: Stockton, at the western border of the Brookside housing development, and north of March Lane along the Tenmile Slough.

Length: Approx. 5,900 ft.

Dates: Scheduled construction start 2025.

Other Info: Upon completion, the levee will be Federally operated. The waterside of levee is farmland.

Phase A – Shima Tract

Type of Work: Levee fix in place with the addition of a cut-off wall, as well as the addition of waterside erosion protection.

Location: North Stockton west of Interstate 5 and north of Schooner Drive to Sturgeon Road.

Length: Approx. 8,400 ft.

Dates: Scheduled construction start 2028.

Other Info: Phase A is the second planned reach to be improved under the Lower San Joaquin River Project. Upon completion, the levee will be Federally operated. The waterside of levee is farmland.

Phase B – Fourteenmile Slough

Type of Work: Levee fix in place and new levees, with the addition of a cutoff wall, height improvements, geometry improvements, and a closure structure.

Location: North Stockton along the Fourteenmile Slough.

Length: Approx. 10,400 ft.

Dates: Scheduled construction start 2032.

Phase C - Tenmile Slough, Calaveras River

Type of Work: Levee fix in place with the addition of a cutoff wall, seismic fixes, and levee reshaping and geometry improvements.

Location: Right bank of the Calaveras River, south of March Lane to N. El Dorado Street (Phase C-2), including a small portion North of the Calaveras on the San Joaquin River (Phase C-1, reaches TS10L and TS20L).

Length: Approx. 28,600 ft.

Dates: Scheduled construction start 2032.

Phase D – Calaveras River, San Joaquin River

Type of Work: Levee fix in place with the addition of a cutoff wall, geometry improvements, height improvements and retention walls.

Location: Left bank of the Calaveras River, north of Monte Diablo Avenue to N. El Dorado Street, including a small portion South of the Calaveras on the San Joaquin River near Smith Canal.

Length: Approx. 27,500 ft.

Dates: Scheduled construction start 2035.

Phase E – San Joaquin River, French Camp Slough, Duck Creek

Type of Work: Levee fix in place with the addition of a cutoff wall, construction of new levees, levee reshaping and geometry improvements.

Location: South of the Port of Stockton along the San Joaquin River, French Camp Slough, and Walker Slough, adjacent to Van Buskirk Park to S. El Dorado Street.

Length: Approx. 30,400 ft.

Dates: Scheduled construction start 2033.

Phase F – Mosher Creek

Type of Work: Levee fix in place with the addition of a cutoff wall and height improvements.

Location: North Stockton from Mosher Slough east to Thornton Road.

Length: Approx. 10,700 ft.

Dates: Scheduled construction start 2032.