Zebra Mussels

Zebra Mussels are native to Eurasia, likely coming to Midwest through ballast water in ships to the Great Lakes in the 1980’s. They hurt native ecosystems by filtering large amounts of water – up to a liter per day for an adult mussel – and feeding on the algae and zooplankton that native species rely on. Zebra mussels live in dense clusters and can spread rapidly. They attach to docks, boats, rocks, logs, and other surfaces in the lake, and can create threats to recreation and to the stability of a lake ecosystem.

Eurasian Watermilfoil

Eurasian Watermilfoil is a submerged plant that typically grows to around 10 feet, but has been observed growing up to 20 feet. It creates dense canopies of vegetation that crowd the surface of the water. Eurasian Watermilfoil spreads easily through fragmentation, where if even a small piece breaks off, it can grow roots and establish a new colony.

Purple Loosestrife

Purple Loosestrife can be found in a majority of the lakes in our District. The native Eurasian plant first made its way to North America in the 1800’s both intentionally, as decorative plants for gardens, and unintentionally, through the soil in ballasts used to weigh down ships. This invasive plant spreads rapidly, crowding out native species and degrading wetlands through its 6+ ft high stalks, extensive root system, and hardy seeds.

Curlyleaf Pondweed

Curlyleaf Pondweed is established in all lakes in the District. Its introduction was likely an unintended side-effect of the introduction of Common Carp. Curlyleaf Pondweed grows in shallow water up to 15 feet deep, and can form a dense mat of vegetation on the waters surface, blocking sunlight and nutrients from reaching native plants.

Brittle Naiad

RPBCWD is 1 of only 3 watershed districts in Minnesota known to be infested with Brittle Naiad. The concern with Brittle Naiad is that it can form dense mats that can outcompete native plants. These dense communities can disrupt fish and waterfowl habitat, choking out plants which animals depend on for survival and potentially decreasing dissolved oxygen levels upon its decomposition. Brittle naiad is a resilient plant; it can survive in some polluted and eutrophic waters and can reproduce by fragmentation.

Common Carp

While technically an invasive species, common carp were actually intentionally introduced to the Midwest in the late 1800’s as a game fish. They spawn rapidly and can be detrimental to the health of our lakes. These bottom-feeders stir up phosphorus-rich sediments while prowling for food in the lake bed, where the phosphorus becomes available as food for algae.