A method is developed for planning cost-effective control programs for toxic pollutants in municipal treatment systems. It chooses the levels of industrial pretreatment and type of municipal sewage treatment a city can use so that all applicable standards and criteria on sewer discharges, receiving water quality, and municipal sludge quality are met at minimum cost. The problem is formulated as a nonlinear 0-1 integer programming model. An implicit enumeration procedure is developed for its solution. The method is applied to control of five heavy metals in Kokomo, Ind. The economic impact of EPA's national pretreatment policies and alternative water quality goals is studied.