In 1987 Congress expanded the scope of the Clean Water Act to include combined sewer overflows (CSOs) despite continuing to reduce federal assistance for water-pollution abatement and despite the fact that CSO abatement is far more costly than previous water-quality mandates. As a result, many low-income deindustrializing cities are now subject to an additional federal mandate that many of them cannot afford without extensive federal or state assistance. The authors conclude that, in lieu of increased federal funding for CSO abatement, U.S. Environmental Protection Agency regulatory guidelines and the Clean Water Act be amended to include an assessment of the fiscal and economic impact of CSO mandates. Such action would provide a basis for targeting the available resources where needs are greatest and the effect of CSO abatement is likely to result in tangible beneficial uses