Clean water in not enough to ensure that lakes and streams are fit for aquatic organisms. Pollution from rural and urban land uses add sediment, nutrients, toxics and pathogens to the water. Sediment, by volume, is the greatest pollutant in Wisconsin s surface waters. Sediment that runs off the land and into the water blankets stream and lake bottom habitat with excess nutrients, making water cloudy reducing the productivity of aquatic ecosystems and blocking sunlight. Water quantity also changes a lake or stream s health.
Flooding can wash vegetation and soil along waterways.
Concrete and pavement carry pollutants, increasing runoff and decreasing spring flow to lakes and streams. The water that enters the stream is warmer and lower in oxygen capacity. Food chains in lakes and streams also factor into an aquatic ecosystem s health. Organic matter such as leaves and other vegetation wash into streams providing food for aquatic insects, which in turn, are food for other aquatic organisms that live there. Mike Miller is a DNR monitoring specialist.