The Nationwide Urban Runoff Program (NURP) was a research initiative conducted by the U.S. Environmental Protection Agency (EPA) between 1979 and 1983 to evaluate the impact of urban stormwater runoff on water quality across the United States. The program found that urban runoff contains significant pollutants, including heavy metals, bacteria, and oxygen-demanding substances, and demonstrated that stormwater management practices such as detention basins and wetlands can effectively reduce pollutant loads. The findings from NURP formed the basis for later stormwater regulations and played a major role in the development of modern stormwater management programs under the Clean Water Act (Wikipedia).