Within Sacramento County, land surrounding the project site is designated on the County General Plan as natural preserve, agricultural cropland, and resource conservation area. Land adjacent to the San Joaquin County portion of the project site is reserved for general agriculture and resource conservation uses. The project bridges cross areas of upland, seasonal wetland, riparian and open water habitat.

The trestle bridge houses one of the largest maternal bat colonies in northern California with a bat population estimated to be 40,000 individuals. The area under the trestle bridge is overflow floodplain from the Cosumnes River. It is typically dry from the early spring until the winter rainy period.

Several special status species, including Swainson's hawk (Buteo swainsoni), western pond turtle (Clemmys marmorata), and giant garter snake (Thamnophis gigas), are known to occur in the Mokelumne/Cosumnes River confluence area.

Open water of the Mokelumne River, to the south of the wooden trestle bridge, provides habitat for anadromous fishes including Central Valley ESU fall-run Chinook salmon (Onchorhynchus tschawytscha), Central Valley ESU steelhead (Onchorhynchus mykiss), striped bass (Morone saxatilis), and American shad (Alosa sapidissima). The federal government has proposed the fall-run Chinook salmon for listing as threatened and has listed steelhead as threatened. A hatchery located just below Pardee Dam, well upstream of the project area, supplements natural spawning of Chinook salmon and steelhead in the river. Sacramento splittail (Pogonichthys macrolepidotus), a fish proposed for listing as threatened by the U.S. Fish and Wildlife Service, may also be present within the project site. The Mokelumne River-Cosumnes River confluence occurs just upstream of the project.

The Cosumnes River Preserve is located to the north of the project site on both sides of Franklin Boulevard. The Preserve is the location of the Cosumnes River Project, a broad-based effort to restore and safeguard the integrity of the Cosumnes River and its surrounding landscape. The Nature Conservancy and its partners established the Cosumnes River Preserve in 1987. By 1998 the preserve had grown to some 13,000 acres. Land owning partners in the project include both the following private organizations and public agencies:

• Bureau of Land Management -- Folsom Field Office
• California Department of Fish and Game
• California Department of Water Resources
• Ducks Unlimited, Inc.
• Sacramento County Department of Regional Parks, Open Space, and Recreation
• The Nature Conservancy of California
• Wildlife Conservation Board

The Cosumnes River, located 15 miles south of Sacramento, is a unique natural resource as it is the largest free-flowing river in the Central Valley of California. The watershed encompasses a rich array of natural communities, including wetlands, riparian (streamside) forests, and vernal pool grasslands. Conservation efforts are currently focused on the lower floodplain of the Cosumnes River and adjacent Delta Wetlands.