The Cosumnes River is a small river, a mere 80 miles long. Its headwaters in the El Dorado National Forest rise at only 8,000' above sea level. From mostly rain, but also snow melt, the river's water meanders from the Sierra Nevada Mountains to the Central Valley, just south of Sacramento.
Yet the Cosumnes River is far more important than its size would indicate. It is the only remaining unregulated river on the western slope of the Sierra Nevada. In its lower reaches, it flows through one of the biologically richestregions in California's Central Valley, before merging with the Mokelumne River to flow into the Sacramento-San Joaquin Delta and eventually the Pacific Ocean. The Cosumnes River Preserve was created to safeguard much of this unique landscape.
The free-flowing nature of the river allows frequent and regular winter and spring overbank flooding that fosters the growth of native vegetation and the wildlife dependent on those habitats. More than 250 bird species, more than 40 fish species, and some 230 plant species have been identified on the Preserve.
The Cosumnes River Preserve encompasses and protects thousands of acres of wetlands and adjacent uplands. These lands, once considered insect ridden, unattractive, and even dangerous, today are recognized as beautiful places with important roles in local and global ecology.
Wetlands provide a diverse habitat critical to the survival of many kinds of plant and animal life. The Cosumnes River Preserve is recognized as one of California's most significant natural areas.