The mussel beds: the river's quiet census

The Maumee basin, surveyed to 2025

Why mussels: Freshwater mussels are the Maumee system's longest-lived residents and its strictest water-quality witnesses, and the basin's documented mussel fauna is the richest animal record this section has after the birds. Indiana's statewide fauna was historically among the richest on the continent; the Indiana DNR's official mussel list, revised February 2025, still carries the rayed bean and the clubshell as both state and federally endangered. The animals depend on fish — their larvae must ride a host fish's gills — so a mussel bed is a certificate that the fish community and the water both work.

The ark in the St. Joseph: The basin's best-documented refuge is Fish Creek, a St. Joseph River tributary in DeKalb and Steuben counties, northeast of Fort Wayne: Spencer Ferrier's watershed study (2026) counts 31 mussel species historically in Fish Creek against 22 to 25 in recent surveys, 64 mussel beds, and four federally endangered residents — clubshell, rayed bean, rabbitsfoot, and the salamander mussel, which lives only with the mudpuppy. The creek's modern history includes the basin's worst mussel disaster: on 15 September 1993 a pipeline rupture in DeKalb County released some 30,000 gallons of diesel through farm tile into the creek, killing fish, mussels, and turtles, and produced a $2,507,500 settlement spent on easements, tree planting, land purchase, and monitoring. The white catspaw, one of Fish Creek's rarities, is believed in Ferrier's account to have been lost from the creek in the 1990s.

Inside Fort Wayne: The mussels reach into the city itself. The U.S. Fish and Wildlife Service's Spy Run Dam removal grant record states that federally listed clubshell, round hickorynut, and rayed bean "historically lived in the Maumee River Basin," and that "the Clubshell and Round Hickorynut were observed in a 2008 mussel survey on the rivers of Fort Wayne." Allen County's comprehensive plan, working from the Indiana Natural Heritage Data Center, lists the county's federally endangered species as including four mussels — white catspaw, northern riffleshell, clubshell, and rayed bean — with the rabbitsfoot federally threatened. The Service's Fort Wayne Rivers Fisheries Improvement Project — removing the Spy Run Dam and two culverts, and studying removal of the Hosey Dam on the Maumee — is justified in its own record by habitat for the endangered rayed bean, clubshell, and threatened round hickorynut and their host fish. The state-listed gilt darter, the plan documents add, was historically found in this watershed too.

Sources:

1. Indiana Department of Natural Resources, "Freshwater Mussels of Indiana List," revised February 2025, in.gov.
2. Spencer Ferrier, "Fish Creek: A Watershed in Layers" (2026) — the 31-to-22/25 species counts, the 64 beds, the 1993 spill and settlement.
3. U.S. Fish and Wildlife Service, Project Grant F24AP00796, Spy Run Dam Removal in the Maumee River Basin (the 2008 Fort Wayne rivers mussel survey), via GovTribe; U.S. Fish and Wildlife Service, Fort Wayne Rivers Fisheries Improvement Project, via the Society's Allen County dams page, acgsi.org.
4. Northeastern Indiana Regional Coordinating Council, Allen County comprehensive plan environmental chapter (Table 21; the Natural Heritage Data Center county list), in.gov.