The Iowa Department of Natural Resources says zebra mussels have been found in Crystal Lake.
The invasive species are native to eastern Europe and are voracious eaters that gobble up plankton many native freshwater fish need to survive. The mussels can attach themselves to boat motors, bait buckets, and dam mechanisms and cause damage to motors and facilities.
The Iowa department says juvenile versions of the small black and white species were discovered in a recent water sample. No adult zebra mussels were found in a follow-up survey. Officials say the mussels probably arrived on or in a boat that had been in an infested water body, such as nearby Clear Lake.
Boaters are urged to clean, drain and dry watercraft to prevent the spread.