The lower St. Louis River estuary is a vital habitat for over 230 bird species, serving as a key stopover for migrants and a breeding ground for many residents. Wetlands, sandy beaches, and open water provide food and shelter for songbirds, shorebirds, raptors, and waterbirds, including species of conservation concern like piping plovers and bald eagles.

The St. Louis River hosts one of the Great Lakes’ most diverse warmwater fish communities, with over 45 native species. Walleye return each spring to spawn, while muskellunge, northern pike, smallmouth bass, crappies, perch, and bullheads are year-round residents. The estuary also supports sturgeon, catfish, suckers, and other native fish.

The St. Louis River corridor is home to a variety of mammals, from beavers, muskrats, and otters in wetlands to raccoons, foxes, deer, and black bears in forests and uplands. Smaller mammals like squirrels, chipmunks, rabbits, and voles thrive along riverbanks. These habitats support wildlife diversity and connect the river to the larger Great Lakes ecosystem.

The lower St. Louis River is a freshwater estuary where natural processes like water depth, clarity, and sediment shape diverse habitats. Wetlands, marshes, and uplands provide food and shelter for fish, birds, and wildlife. Seasonal water changes, human impacts, and historic dredging influence these dynamic ecosystems, which remain vital to the Great Lakes region.