An important task in environmental planning is interpretation of data. Indicators, statistics or other measures of conditions or performance often are used to simplify complex data sets and to facilitate plan-making and policy development. With increased need to stretch scarce resources for environmental protection and to target activities that pose the greatest risk, there is significant new interest in the development of indicators and indices. General frameworks are available for describing both the structure of indices and different descriptive or analytic approaches in which they can be used. This paper describes the use of environmental indicators in planning for wellfield protection in Indianapolis, Indiana. Advisory committees used indicators of development activity, indices of chemical risk and an index of the desirability of management alternatives in developing a set of recommendations for groundwater protection that were adopted by the city-county council. While the indices were not incorporated directly into regulatory schemes, they were useful for informing debate and focusing argument over regulatory options.