Optimizing Sampling Intervals in Tidal Estuaries

Automatic collection of water quality and other hydrologic data in tidal estuaries can easily exceed the capacity of available data processing and interpreting functions and may, in fact, provide more data than are needed for any given situation. Spectral analyses and other statistical studies of dissolved oxygen and conductivity data from the Potomac River and Raritan Bay were made. These studies revealed that for those areas where data are to be evaluated monthly, the optimum sampling interval is 2 hr. Routinely collected data from inland streams confirm the intuitive reasoning for estuaries that as a dominant source of pollution is approached, more frequent sampling is necessary. In any case, optimum sampling, statistical, and evaluation efforts must be adapted to both the environment and the intended use of the data.