Cosumnes River Preserve, Protected wetlands and oak forest area in Sacramento Valley, United States.

The Cosumnes River Preserve is a protected area featuring wetlands, grasslands, and oak forests along one of California's last free-flowing rivers in the Central Valley. The landscape contains several habitat types that together create a diverse environment supporting a wide range of wildlife.

The Miwok Native Americans managed these lands through sustainable practices before Spanish explorers arrived in the late 1700s and altered the population structure. This period of change reshaped the region and introduced new patterns of land use.

The preserve functions as a learning hub where knowledgeable staff share insights about local ecosystems and wildlife protection with visitors. People come here to understand how this landscape supports both nature and human communities.

The grounds can be explored on trails accessible to different mobility levels and offering views of various landscape types. The visitor center with exhibit areas remains open frequently and provides helpful orientation for exploring the property.

The preserve's Tall Forest, an old-growth stand of valley oaks and cottonwoods in Wood Duck Slough, is where the Nature Conservancy found the best remaining valley oak stands in the 1980s. The valley oak is also called swamp oak because it grows on deep alluvial soils that seasonal floods deposit — the same soils that make good farmland.