Material which commonly reside on street surfaces have been found to contribute substantially to urban polution when washed into receiving waters by storm runoff. In fact, runoff from street surfaces is similar in many respects to sanitary sewage. Calculations based on a hypothetical but typical U.S. city indicated that the runoff from the first hour of a moderate-to-heavy storm would contribute considerably more pollutional load than would the same city's sanitary sewage during the same period of time. This study provides a basis for evaluating the significance of this source of water pollution relative to other pollution sources and provides information for communities having a broad range of sizes, geographical locales, and public works pracices. Information was developed for major land-use areas within the cities (such as residential, commercial and industrial). Runoff was analyzed for the following pollutants: BOD, COD, total and volatile solids, Kjeldahl nitrogen, nitrates, phosphates, and a range of pesticides and heavy metals. This report was submitted in fulfillment of Project No. 11034 FUJ, Contract No. 14-12-921 under the sponsorship of the Water Quality Office, Environmental Protection Agency.