Mumford Dam Fish Passage & Riparian Restoration Project

A partnership between the Sonoma County Water Agency, California Department of Fish and Game, Coastal Conservancy, Pacific States Marine Fisheries Commission and American Rivers to provide fish passage over a major barrier to anadromous fish migration on the main stem of the Russian River.

Background

Mumford Dam was a 60-foot wide, 11-foot high diversion dam spanning the west fork of the Russian River, one mile upstream of the town of Redwood Valley in Mendocino County, at the top of the Russian River watershed. The dam was built in the early 1900s, and is used to divert river water for vineyard irrigation and frost protection.

See a video of chinook migrating through the newly-restored habitat:

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Over time, degradation of the riverbed below the dam caused downcutting, making the dam impassable for much of the year. Only during higher winter flows could migrating fish navigate past the structure. Erosion and bank failure have also occurred downstream of the dam.

Project Development

Working together, the Sonoma County Water Agency, California Department of Fish and Game, and the private owners in the area planned and designed a solution to:

restore anadromous fish passage by building a series of weirs that act like "steps" to help the fish move gradually up and over the dam. Migrating fish will have access to nearly fifty miles of previously inaccessible spawning and rearing habitat;
stabilize the eroding stream banks by re-contouring the stream banks to a more stable angle and stabilizing the toe with large rocks and willow spriggings; and
restore the riparian habitat surrounding the river by revegetating the newly contoured stream banks with appropriate native trees and vegetation. The trees and other vegetation help to keep the water temperatures cool for the migrating fish, as well as add valuable habitat and nutrients to the water.

Funding for the project was provided by Fish and Game, American Rivers, California Coastal Conservancy, Sonoma County Water Agency, and the California Department of Salmon and Steelhead Trout Restoration Account.

"The removal of Mumford Dam is another link for the conservation and recovery of salmon in the Russian River," said Patrick Rutten, field supervisor in the Protected Resources Division of NOAA Fisheries. "The real success story is the cooperation of multiple agencies and the landowner in restoration of this fish passage ... this project clearly demonstrates that there are fishery and land use solutions when there is communication and common ground."

Project Description

The project design is based on development of a series of cross-vane weirs over 560 feet of channel to raise the bed elevation of the river to create passage over an 11-foot drop at the dam apron. The weir design follows the design criteria developed by Dave Rosgen and is supplemented by HEC-RAS modeling for current and design channel configurations. In addition to weir construction, banks were regarded to a stable profile, erosion control fabric installed on all exposed slopes and native vegetation planted.

Implementation

The construction portion of the project took place during the low-flow summer and fall months, to minimize the effects on any juvenile salmonids that may have been present. The revegetation effort started in November 2003, and trees were planted in December. The selected plants for the area include willow, California bay, white alder, California buckeye and Oregon ash. An irrigation system was installed in the spring of 2004, and will remain in place until the vegetation is firmly established.

The first migrating chinook began using the ladder in December 2003. Over the winter, periodic heavy rains contributed to two bank failures. One failure, on the east bank, was stabilized in January. The second will be repaired in July 2004.

"The fish ladder performed very well over the winter," said Sonoma County Water Agency Senior Environmentalist Ron Benkert. "We documented many adult Chinook and steelhead passing the structures and old dam location through January. This spring we installed a five-foot screw trap below one of the weirs and captured more than 1,000 Chinook smolts over a three-week period. We also captured 50 to 60 steelhead smolts. We couldn't be happier, and consider the Mumford Dam Fish Ladder a successful project so far."

Project site before removal of dam abuttment	Project site after removal of dam abuttment
Eroded bank prior to regrading	Eroded bank after regrading and revegetation
Finished cross-vane weirs, bank protection, regraded and revegetated banks