ABSTRACT
The construction and upgrading of waste-water treatment plants to treat municipal sewage have played a major role in improving the nation's water quality. The percentage of impervious surfaces in a watershed or subwatershed is a key measure of the likelihood of long-term and persistent threats to water quality. Impervious coverage, such as roads, parking lots, and buildings, impedes water absorption and infiltration into the groundwater. Planning for water quality begins with identifying surface watersheds, groundwater aquifers, and existing and potential water pollution sources. Counties, regional planning commissions, and nonprofit organizations can play key roles in maintaining and improving water quality, especially when their efforts focus on an entire watershed. Ideally, water-quality planning should be combined with planning for sustainable water supplies. Counties that have land-use planning and zoning authority are in a good position to make a positive impact on water quality.
