Without the protection afforded by streamside forests, rivers and streams are vulnerable to being degraded by a host of pollutants, many of which pose specific problems relating to public and private water supplies. Excessive sediments carried into rivers by stormwater and other means harm water supplies by damaging water treatment pumps and other equipment, increasing treatment costs to remove the sediment, and reducing reservoir storage capacity. Sediment can also decrease river bottom infiltration, reducing the yield of nearby wells. In addition, chlorine is generally less effective as a water treatment disinfectant if the water has a high level of suspended sediment particles. A related problem is that removing streamside forests leads to an increase in water temperature and sunlight, both of which can contribute to increased algae growth.
Metals coming from urban runoff have several adverse impacts.
First, they increase the costs of treatment to remove the metals. Second, they also can form deposits in pipes, reducing their carrying capacity. Third, they can color water, leaving stains on fixtures and clothing. Last but not least, there is a possible human health hazard from toxic metals that may not be removed by prior treatment. As the state's remaining inventory of relatively pristine waters continues to come under threat of contamination, we must consider all such water sources as potentially necessary for public or private water supply.