Arroyo Canal Fish Screen and Sack Dam Fish Passage Projects

 A major milestone was reached for the projects when the first concrete was placed for the river bypass on May 13. A commemorative photo was taken, harkening back to the era of peak Reclamation construction.

A series of concrete placements will form the river bypass channel in order to reroute the San Joaquin River and allow for fish passage around the existing Sack Dam and Arroyo Canal inlet. Water users will no longer use the 80 year-old Sack Dam to create the river elevation needed to make water deliveries to the gravity-fed Arroyo Canal. Instead, a new headworks structure will be constructed to create the water elevation needed to continue supplying the canal while meeting in-stream flow requirements.

Concrete for the river bypass channel walls will be poured in sections throughout the month of May before construction efforts turn to construction of the fish ladder and headworks components.

Below is a short video showing the recent construction efforts.

A total of 490 piles will be driven on site to provide structural support for the river and fish bypass channels, with hundreds currently having concrete placed as part of the river bypass channel. The video below highlights the pile-driving action!

Excavation of the main fish passage and river channels started in January and was completed in March 2026. 

In November and December 2025, crews completed vegetation clearing the east bank of the project area, including installing sheet piling to protect the project site from San Joaquin River flows.

The Arroyo Canal Fish Screen and Sack Dam Fish Passage Project, like the Mendota Pool Bypass and Reach 2B Project, is integral to restoring spring-run Chinook salmon to the San Joaquin River. View a project fact sheet here!

This project is necessary in order to allow salmon to freely move up and down the river to complete their lifecycle (downriver to the ocean and upriver to spawn).