The symposium on Water Quality Measurement and Instrumentation has focused attention on an important problem in the water pollution control programs of the nation. Intensified efforts by industry and governmental agencies will be needed to apply to this effort technological experience already at hand in other fields. Available instrumentation must be adjusted to the demands of more or less continuous monitoring of stream quality. Devices are needed which will detect, measure, and record continuously at least the more important of those water quality constituents that can now be determined only at the laboratory bench.