Tribal leaders in Montana have declared a formal emergency over invasive mussel larvae in reservation waters and Flathead Lake.

The Confederated Salish and Kootenai Tribes declared the emergency on December 20. The resolution calls for the formation of an incident management team in response to larvae found in Tiber and Canyon Ferry reservoirs, the Milk River near Malta and the Missouri River near York. The tribal team would work with the state and other groups fighting the invasive species.

Invasive mussels rapidly multiply and can damage beaches, clog boat motors and dams, harm fish and wildlife and damage infrastructure. Traces of contamination are so far restricted to the Missouri River Basin, but there is potential for mussels to spread by clinging to the hulls of boats.