Mattole River, CA
Throughout the Mattole River watershed, poorly designed and installed culverts are being systematically evaluated and replaced to improve fish passage and stabilize sediment that may wash into spawning gravels. Because the Mattole River watershed is subject to extreme storm events and flooding, bridges, followed closely by open bottom culverts, are often the best option for road passage across perennial streams of this size.
The projects being undertaken by the Mattole Restoration Council, and which are funded in part through the American Rivers-NOAA Community-based Habitat Restoration Partnership, also serve to increase access to suitable spawning and rearing habitat. The continued survival of our endangered Mattole salmonids – chinook, coho, and steelhead – is dependent on protecting and enhancing available habitat. The projects described below have been completed over the last few years and have accomplished both the objectives of repairing natural river functions, such as the transport and sorting of stream gravels, which are required for spawning, and providing access to additional habitat for these species.
Van Auken Culvert Replacement
This project replaced an antiquated, undersized, poorly placed culvert on Van Auken Creek, a tributary of the Mattole, with a bridge. The new bridge reduced the risk of failure and allows for unobstructed passage of both fish.
Goff and Thock Culvert Replacement Project
The Project improved access to important fish spawning and rearing habitat in Ravasoni and Thomson Creeks by removing two antiquated culverts that previously partially blocked juvenile and adult fish passage. The culverts were replaced with bridges and opened an additional 2.1 miles of fish habitat. Furthermore, these culverts were poorly placed and covered in unstable road fill, presenting a high risk of failure.
Thompson Creek Culvert Replacement
The Mattole Restoration Council replaced two side-by-side culverts with a forty-foot steel bridge. The upgrade improved sediment transport and delivery and resulted in unimpeded passage to an additional 1.5 miles of spawning habitat for migrating juvenile salmonids.