PUB00136 - Laserfiche WebLink

Home Browse Search

The Cosumnes is the largest river in California's Central Valley never to have been dammed, and may offer the best opportunity for restoring an example of what was once a typical Sierra Nevada river, The 1 ,200-square-mile watershed is unique in that it represents a complete ecological transect of a Sierra river system from high-altitude forest to lowland marshes, From its headwaters in the El Dorado National Forest south of Lake Tahoe, the river tumbles out of the Sierra until it fans out west of Galt and joins the Mokelumne River just east of Snodgrass Slough, The name Cosumnes Is believed to derive from a Miwok Indian phrase meaning "people of the salmon," Indeed, salmon migrate through the Delta to spawn in the upper reaches of the river, but their numbers have dwindled to only a few hundred in recent years, Because its natural flow was irregular and highly seasonal, the Cosumnes never was dammed for irrigation, flood control or hydroelectric power, but much of the native riparian oak forest was removed when land was developed for agriculture, Concern about shrinking stands of Central Valley native oaks led The Nature Conservancy to establish in the early 1980s an 800-acre Cosumnes River Preserve. It has since grown to almost 40,000 acres, and involves numerous partners such as neighboring farmers, state agencies, the Bureau of Reclamation, the USFWS, the Bureau of Land Management and Ducks Unlimited, As the preserve's size grew, so ". ,f,!' "..' . -.' '. '.f" - :' ,,,:Jii - y"Ce. f -" ~1i:~ . ie" did restoration activities, Starting from modest acorn-planting projects, preserve managers have expanded the mission by experimenting with strategic levee breaks that partially re-create the river's natural floodplain and maintaining wetlands that support a rich array of resident and migratory birds, About 800 acres of oaks carefully planted begin- ning in 1989 now thrive on seasonal flood waters. In 1995, preserve managers breached levees in two areas and let the river follow its natural course, The result was 300-acre young forest of cotton- woods and willows that will be succeeded by oaks over the next 30 to 50 years. Biologists also have found juvenile salmon in some of the flooded areas, leading to speculation that floodplain areas may be an important link in the salmon's transi- tion from fresh water to salt water, The Cosumnes River Preserve is an example of cooperative restoration. The preserve itself is a patchwork of mostly contiguous properties managed cooperatively by The Nature Conser- vancy and various state and federal agencies. However, adjacent farmers also participate by selling easements for restoration activities and agreeing to follow farming practices that support the preserve's goals, The preserve hosts a 1,000- acre private rice farm. To enhance habitat values and control weeds, rice farmers plant only two years in a row, then let their fields lie fallow for a year as wetland habitat for migratory birds and waterfowl. 15