Dropping the level of the pond at least four feet after ice has started to form on the pond will freeze the leeches in the mud. This measure is effective but it will also kill other forms of aquatic life that burrow in the mud. This method would not be allowed on State owned bodies of water because of the impact on other aquatic life. Since leeches prefer the shallow areas of lakes, swimming in deeper waters will reduce the risk of a leech attaching to a swimmer. A boat or float can be used to get to the deeper water or a person can swim out to the deeper waters.
Leeches are important in the food web of a lake.
They are predators, prey, parasites and vectors of parasites. The leeches of North America are not nearly as serious a pest as tropical leeches. However, leeches are bothersome to humans in areas used for swimming.