Zebra mussels have infested metro are lakes. While it is too early to know all of the effects this will have on using lake water for irrigation, this is what we do know. Not all lakes have the same rate of infestation, for information on your lake visit the MN DNR website. Zebra mussels will grow inside the suction filter in the lake. For areas with established populations we recommend a monthly external inspection and cleaning of the lake screen. In August an internal inspection and cleaning of the screen should be done, our observed muscle growth inside the lake screens in 2011 was much greater than what attaches on the outside of the screen. Specimens are needed to confirm sightings, in Minnesota, possession and transport of zebra mussels is illegal, except when providing them to the DNR for identification. Unauthorized introduction of zebra mussels, fish, or plants into the wild is illegal.