La Grange Floodplain Restoration and Spawning Gravel Augmentation

Project Lead: Tuolumne River Trust

Potential Project Partners:
Stanislaus County Parks and Recreation

Short Project Description:
Restore 77 acres of degraded floodplain habitat along the Tuolumne River in La Grange while developing a source of spawning gravel to improve and enhance existing spawning beds in the Tuolumne River.

Long Project Description:
The floodplain in the project area was heavily altered by gold dredging operations in the 1930's-1950's and has never recovered. As a result of the gold dredging, the floodplain has become armored and it supports little riparian vegetation. Additionally, the floodplains adjacent to the rivers are artificially elevated and disconnected from the channel. Coupled with the heavily altered flow regime, the gravels are rarely, if ever, activated, thus they provide no benefit to spawning salmonids. Meanwhile, the in-channel spawning beds are heavily degraded because they cannot be replenished through normal geomorphic processes because of the sediment-blocking of Don Pedro and La Grange Dams. Through this project, we will harvest gravels from the floodplain and place them in the spawning riffles, while simultaneously lowering and revegetating the floodplain.

Stanislaus County presently owns approximately 200 acres of Tuolumne River floodplain near the town of La Grange. The land extends from approximately RM 49.2 - 50.6 on the south bank and from RM 49.9 - RM 50.6 on the north bank. This is a proposal to undertake a project on about 77 acres out of the 200 acres of county land. The project is floodplain and riparian restoration to recreate a more natural environment for the benefit of riparian species, San Joaquin fall-run Chinook salmon, and steelhead. The project will improve riparian habitat along the lower Tuolumne River, and improve chinook salmon and steelhead spawning and rearing habitat. The following goals will be met by implementing this project: recovery of at-risk native species (Central Valley steelhead and Central Valley fall-run Chinook salmon), restoration of fish spawning and rearing habitat, rehabilitation of natural channel-floodplain processes, and rehabilitation of native riparian habitat. The goal of this project is to improve the functionality of the Tuolumne River floodplain and channel to provide riparian habitat to support riparian species and San Joaquin fall-run Chinook salmon and steelhead trout.

The primary objectives for the restoration project are:

  1. Restore functional floodplains that allow inundation at a greater frequency and reduce risks of juvenile salmonid stranding.
  2. Restore native riparian vegetation by preserving existing native vegetation and planting the appropriate species on restored surfaces inundated by the contemporary hydrologic regime.
  3. Exclude trespassing cattle from the county property by building fences.
  4. Build a loop trail consistent with the restoration project to improve recreational access and utility.

Unique Project Characteristics:
None specified

Project Status Pre-planning
Project Cost $1,500,000
Project Timeframe 1-5 years
Cost-sharing VNo opportunities identified to date
Multi-benefit Project Yes
Types of benefits The project would improve flood risk management, promote ecosystem functions, and promote multi-benefit projects.
Source of Project East Stanislaus Integrated Regional Water Management Partnership

Background Information:
East Stanislaus Integrated Regional Water Management Partnership website: http://www.eaststanirwm.org/