Hallwood Fish Habitat Project

The Hallwood Side Channel and Floodplain Restoration Project is designed to enhance the lower Yuba River ecosystem by increasing available juvenile salmon habitat to improve the natural production of Chinook salmon and Central Valley steelhead. The project will also reduce flood risk through lower water surface elevations and velocities during flood events. 

Restoration Update - April 2021

In November 2020, Phase 1 of the Hallwood Floodplain and Side Channel Restoration Project wrapped up. Over 1.2 million cubic yards of sediment was removed to expose historic floodplain habitat for Chinook salmon, steelhead and sturgeon. Miles of seasonal and perennial side channel habitats were carefully engineered to provide additional rearing habitat for native salmonids like Chinook salmon. Floodplains and side channels offer refugia for juvenile Chinook salmon and rainbow trout/steelhead to grow big and strong because these areas provide protection from predatorsRainbow trout swimming beneath the surface of the river.. They also offer warmer waters that promote vegetation growth and, in turn, promote the growth of aquatic insects that ultimately increase the likelihood juvenile salmon survive.  

Even before construction was complete, adult Chinook salmon were observed spawning in the reconstructed side channels! Post-construction, juvenile Chinook salmon have been observed at all the monitoring sites throughout the project footprint. Juvenile steelhead, otters, eagles, deer, beavers, lamprey, and even a bear have also been observed enjoying the new habitat.


Phase 1 Construction

An aerial view of the lower Yuba River.                                                                 Before                                                  After 

A aerial photo comparing the lower Yuba River at different times.

A aerial photo comparing the lower Yuba River at different times.

An aerial photo comparing the lower Yuba River at different times.

Background

In the project area, the Yuba River is constrained by tall, linear cobble embankments called training walls, which were constructed in the early 1900s by hydraulic dredges following the Gold Rush. These training walls are within the highly modified Yuba Goldfields setting where hundreds of millions of cubic yards of hydraulic mining sediment was deposited in the lower Yuba River through the early 1900s. The area was subsequently dredged multiple times, creating significant impacts for the natural flow of the river and the floodplain. A large training wall in the middle of the river, known as the Middle Training Wall, runs more than two miles long the length of the project. 

Hallwood fish project location map

The Project Plan

The project design is based on the premise that restoration of natural river and floodplain processes, including the removal of large portions of the Middle Training Wall, will create a healthier, more natural, and therefore, more productive river. Improvements will enhance up to 157 acres of seasonally inundated riparian floodplain, approximately 1.7 miles of perennial side channels, and approximately 6.1 miles of seasonally inundated side channels, alcoves, and swales. Enhancements will be made through land surface changes, riparian planting, and placement of large woody material embedded to simulate a more natural river at key locations. The total project cost is estimated to be $6 million. Funding has been provided by USFWS grants and Yuba Water Agency. 

Hallwood Side Channel and Floodplain Restoration Project graphic, showing potential benefits

Project Partners

This project is a collaborative effort among many different organizations. Primary partners include: U.S. Fish and Wildlife Service, cbec eco engineering, South Yuba River Citizens League, Cramer Fish Sciences, Yuba Water Agency, Teichert and Western Aggregates.