Click on each yellow dot to learn about a different type of habitat or area at Cosumnes River Preserve!

Cosumnes River Preserve Habitat

Cosumnes River Preserve Habitat
Willow Slough Managed Wetlands Middle Slough Oak Savanna Grassland Cosumnes River Managed Wetland Ponds Tule Marsh Riparian Forest Cosumnes and Mokelumne River Confluence Tihuechemne Slough

Willow Slough

The first bridge along the Wetlands Walk Trail takes you over Willow Slough.

A slough is a river channel that has no outlet. At the bottom of the map you'll find Cosumnes River going East to West. The Cosumnes River flows into Middle Slough, which then flows into Willow Slough (the highlighted portion).

The water in a slough is stagnant or may flow slowly and the sloughs surrounding the Cosumnes River are influenced by the tides from San Francisco Bay.

Managed Wetlands

In this portion of the Preserve you'll find managed wetlands. These wetlands are flooded in the late fall and continue to have water throughout the winter and early spring, providing roosting and foraging habitat for thousands of waterfowl. Though natural flooding of the wetlands occurs, Preserve Staff manage the wetlands to allow for enough habitat to support birds migrating along the Pacific Flyway.

To watch a video and learn more about managed wetlands, click HERE.

Middle Slough

Middle Slough is visible from marker 7 and 8 on the River Walk Trail. If you utilize our boat launch, you paddle through Middle Slough before accessing the Cosumnes River. This slough is directly off the main Cosumnes River channel and branches off into other sloughs, such as Willow Slough.

A slough is a river channel that has no outlet. The water in a slough is stagnant or may flow slowly.

Oak Savanna Grassland

This wide-open grassland is scattered with valley 0ak (Quercus lobata) trees, making for a Valley Oak Savanna. This important habitat is utilized by grazing animals, nesting birds, and rodents. As you walk along the trail, you may see a northern harrier, red-tailed hawk, or other raptor perched on a tree branch or diving into grasses.

During the spring, you'll find an array of native wildflowers blooming across the open fields. In the winter and early spring, this area is an important part of the Cosumnes River floodplain. The open grassland helps with flood management by proving a space for flood water to be stored, rejuvenating and recharging groundwater.

Cosumnes River

The Cosumnes River is over 50 miles long and is one of the last free-flowing rivers west of the Sierra Nevada mountain range. As a free-flowing river, this means it does not have any major dams or levees that prevent it from seasonally flooding and flowing over to provide essential habitat for plants and wildlife.

The river is also important habitat for Chinook salmon and steelhead trout, who migrate up the river from the ocean and back down during their life and breeding cycle.

Managed Wetland Ponds

This area consists of multiple managed wetland ponds. During the summer months this area is mostly, if not completely, dry. Preserve staff gradually flood these ponds during the fall and winter months to provide essential habitat to migrating waterfowl, shorebirds, invertebrates, and other wildlife.

To watch a video and learn more about managed wetlands, click HERE.

From the boardwalk trail you can experience the vastness of this area and during the winter months, you will likely see swans, geese, ducks, cranes, and shorebirds.

Tule Marsh

Just west of the majestic valley oak tree at post #22, you'll see a natural tule-marsh. Tule is a bulrush plant and is an important part of wetland vegetation. Tule marshes used to be abundant in the Central Valley, but the habitat has been degraded over the years.

This marsh is roosting habitat for the red-winged blackbird and black-masked common yellowthroat.

Tule is not only important habitat for wildlife, but is an essential resource for the Miwok people (original inhabitants of this area), who use them to make coverings for their homes and mats for sitting and sleeping.

Riparian Forest

A riparian forest is a woodland located along streams and rivers. These forests provide habitat and cover for a variety of wildlife and also cast shade over rivers and streams to help moderate the temperature of the water for fish. The trees and shrubs provide nesting and foraging habitat for many species of birds and mammals.

In addition to being a crucial wildlife habitat, a riparian forest is one of many vegetation types found on floodplains. Floodplains are natural flood control because they provide space for the flood waters to flow. They help to slow the overflow of water from rivers and streams and reduce erosion on stream banks.

Due to development, urbanization, and other impacts, the total acreage of valley oak riparian forest is less than 2 percent of what it was in the mid-1800s.

Cosumnes and Mokelumne River Confluence

The Cosumnes River flows west into the Mokelumne River. The rivers meet just before the river runs under Franklin Blvd. The Cosumnes river and sloughs surrounding the Preserve as well as the Mokelumne river are all part of the Delta. Because of this, the Cosumnes River is tidally influenced by the San Francisco Bay.

Tihuechemne Slough

A slough is a river channel that has no outlet. The water in a slough is stagnant or may flow slowly.

Tihuechemne Slough branches off from the Cosumnes River and is accessible to visitors by boat. In this area you'll likely see egrets & herons, and hear the many sounds of other waterfowl flying overhead.