| Fast Facts |
location
20 miles south of Sacramento
ecoregion
Great Central Valley
project size
800 square miles
preserves
Cosumnes River
partners
Bureau of Land Management, Ducks Unlimited, California Department of Fish and Game, California Department of Water Resources, State Lands Commission, Sacramento County
conservancy initiatives
Fire, Freshwater, Invasive Species
natural events
sandhill crane migration, September–March; Sandhill Crane Festival, early November | |
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The last free-flowing river on the western slope of the Sierra Nevada, the Cosumnes is now threatened by encroaching suburbs and growing demands for water. |
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Cosumnes River.
© Mike Eaton/TNC |
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The Cosumnes River is an anomaly in the heart of California’s breadbasket—the last undammed river in the heavily irrigated Central Valley. The Cosumnes flows freely from its headwaters in the red fir forests of the Sierra Nevada to its confluence with the Mokelumne River and the marshes of the Sacramento–San Joaquin Delta. Its brown waters mosey sleepily along a broad, shallow course in the valley but are transformed by winter rains, surging and routinely flooding their banks. Ocean tides push nearly 100 miles up the delta, creating freshwater tidal wetlands in the river’s lower reaches.
Stretches of the river are today much as they were when described by explorer John C. Fremont in 1844—laced with sloughs, ponds, oak woods and fertile bottomlands. Within the watershed are extensive seasonal wetlands known as vernal pools, which fill with rain in the spring and evaporate in the summer heat. These fleeting oases beget wildflowers and the endangered fairy shrimp, whose eggs lie dormant in the soil until the rains come. |
Valley oak.
© Wendy Shattil/Bob Rozinski |
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The marshes and grasslands of the Cosumnes are wintering grounds for tens of thousands of migrating birds, songbirds and raptors, among them lesser and greater sandhill cranes, tundra swans and great blue heron. The river itself is home to a number of native fishes, and Chinook salmon are showing signs of rebounding after years of decline. | |
More than a century ago, settlers discovered the Central Valley’s rich soils and began to clear forest and drain wetlands to make way for crops. Today, wedged between the bustling cities of Sacramento and Stockton, the agricultural land flanking the Cosumnes is increasingly targeted for suburban development. The land’s continuation as farmland is a key conservation strategy, as it provides habitat for wildlife and helps buffer important streamside areas from the effects of urbanization.
In 1995, The Nature Conservancy and local farmers developed a 1,040-acre organic farm on the Cosumnes River Preserve. Since then, we have protected more than 20,000 acres of private farmland and rangeland in the watershed through conservation easements, and 10,000 acres more through direct purchase. A new Conservancy subsidiary—Conservation Farms and Ranches, Inc.—will manage day-to-day farming operations and ensure professional management of these critical properties.
Learn more about The Nature Conservancy's work in California. |
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| Conservation Profile |
targets
Cosumnes River, valley oak forest, blue oak forest, vernal pools, salmon, giant garter snake, sandhill crane and other wintering and year-round birds
stresses
habitat destruction due to urbanization, groundwater pumping, incompatible agricultural practices
strategies
build conservation alliances, promote compatible agricultural practices, influence land-use planning, acquire land, secure conservation easements
results
40,000 acres in conservation management; 1,040-acre organic farm established; 1,500 acres of riparian forest restored | | | | |
