The possible deleterious water quality effects of non-point sources in general, and urban runoff in particular, were recognized by the Water Pollution Control Act Amendments of 1972. Because of uncertainties about the true significance of urban runoff as a contributor to receiving water quality problems, Congress made treatment of separate stormwater discharges ineligible for Federal funding when it enacted the Clean Water Act in 1977. To obtain information that would help resolve these uncertainties, the Agency established the Nationwide Urban Runoff Program in 1978. This five-year program is intended to answer questions such as: To what extent is urban runoff a contributor to water quality problems across the nation. What is the effectiveness of controls short of treatment in reducing water quality problems where they exist. Are best management practices for control of urban runoff cost effective in comparison to alternative options.