The arrivals: zebra mussels in the river, carp at the gate

The agencies' standing as of 2026

Zebra mussels — present, on the state's own list: The Indiana Department of Natural Resources keeps an official list of the state's zebra mussel waters, and on that list — updated 12 January 2026 — St. Joseph County's entry is the St. Joseph River. The mussel, a Black and Caspian Sea species carried to the Great Lakes in ship ballast in the 1980s, is established in this river as a matter of the managing agency's published standing, printed here as exactly that. The river's zebra mussel science was in part done here: researchers at the University of Notre Dame surveyed zebra mussel populations in the coupled lake-and-stream systems of the St. Joseph River basin in 2000 and 2003 and modeled the mussel's downstream spread from the basin's invaded lakes — finding adult densities falling with distance below the invaded lake outlets, a source-and-sink pattern, in the basin's own studied waters. The file records the arrival without embroidery: the river that Chapman listed for its native suckers and catfish now carries, on the state's list, an Eurasian mussel in its St. Joseph County reach.

The invasive carps — not here, on the agencies' standing: The bighead, silver, grass, and black carps — the "Asian carps" of the agency literature — stand in Indiana, on the Indiana DNR's own factsheet, in "the Ohio, White, and Wabash rivers, where they are now common." The St. Joseph River of Lake Michigan is not in that sentence, and no established population of any invasive carp in this river, or in Lake Michigan itself, appears in the agency record: the standing campaign, run by the Invasive Carp Regional Coordinating Committee and its member agencies, is aimed at preventing establishment in the Chicago Area Waterway System and Lake Michigan, and its 2025 interim report records no invasive carp detected upstream of the Brandon Road Lock and Dam on the Illinois waterway.

The Kankakee complicates the geography and the file states it exactly: this county's river of the west drains to the Illinois, and in 2025 the U.S. Fish and Wildlife Service captured and removed two bighead carp, 490 silver carp, and ten grass carp from the Marseilles and Dresden Island pools and the lower Kankakee River — the Illinois reach of the Kankakee, far below the Indiana line, in an active removal fishery; and in August 2026 Illinois authorities found several hundred small silver carp in the Marseilles Pool, some eighty river miles from Lake Michigan, the first fish of that size found that far upriver since monitoring began in 2010. The Indiana reach of the Kankakee, rising in this county, stands above the documented front; the St. Joseph stands outside the invaded system altogether, behind the lake. That is the standing as the agencies state it in 2026 — a front held downstream and a river not yet entered — and the file prints it as standing, not as alarm and not as comfort.

Sources:

1. Indiana Department of Natural Resources, "Indiana Zebra Mussel Waters" (list updated 12 January 2026), in.gov — St. Joseph County: St. Joseph River.
2. Angela M. Bobeldyk et al., "Secondary spread of zebra mussels (Dreissena polymorpha) in coupled lake-stream systems," Écoscience 12(3) (2005) — the 2000 and 2003 St. Joseph River basin surveys (University of Notre Dame).
3. Indiana Department of Natural Resources, "Asian Carp" invasive species factsheet — the carps' Indiana distribution in the Ohio, White, and Wabash rivers.
4. Invasive Carp Regional Coordinating Committee, 2025 Interim Summary Report — removals in the Marseilles and Dresden Island pools and the lower Kankakee River (2025); no invasive carp upstream of Brandon Road; and Illinois DNR's August 2026 Marseilles Pool finding, as reported that season.