 The Minnesota DNR reports zebra mussels have been discovered in three more lakes in the state. Invasive species have been found at Union Lake in Polk County and First Silver and Heilberger Lakes in Ottertail County. The DNR is urging Minnesotans to remain vigilant and keep an eye out for these mussels, particularly as they can attach to boats and other hard surfaces, making it easier for them to spread to other lakes and colonize new habitats.