ST. PAUL (AP) — The Minnesota Department of Natural Resources says zebra mussels have spread to a popular fishing lake in northwestern Minnesota.

The agency said Friday the invasive pest was confirmed in Cass Lake in Cass County.

Someone found the zebra mussels this week while collecting shells on the beach on Cedar Island.

DNR invasive species specialist Nicole Kovar says it’s the first confirmed adult zebra mussel find in the Bemidji area.

Cass Lake will be designated as zebra infested. The reach of the Mississippi River between Cass Lake and Lake Winnibigoshish also will be designated as zebra mussel waters.

Some nearby lakes and their connecting rivers also will be designated as infested. While no zebra mussels have been found in those lakes, they are heavily used by boaters traveling from Cass Lake.