Sidestream monitoring is monitoring for the zebra mussel, in any of its life stages, using a pipeline from the source water as the monitoring field. The source water consists of the body of water from which the facility draws (e.g., a lake, a large body of water, a stream or river). From the pipeline or the raw water distribution system of the facility, the source water is guided through a series of bioboxes/monitors that mimic the conditions of the facility. The effectiveness of the sidestream monitoring system lies in the fact that zebra mussels are detected as they enter the plant and the components are readily examined and closely monitored.
A variety of monitoring devices and sampling equipment are deployed to gather data on mussel dispersal, abundance, development, settling, and mortality. Both qualitative and quantitative data may be recorded depending upon the needs of the facility or site. The accuracy of installing the monitors and monitoring techniques at the site of the raw water intake leaves less to chance than mainstream monitoring. It must be remembered, however, that although sidestream monitors indicate fouling, they do not always indicate the extent of the fouling; the flow characteristics in the monitors may be either more or less conducive to settlement than in the piping system. More information on sidestream monitoring can be found in Claudi and Mackie (1994).
For information on which sampling gear and techniques may be most useful, see the Monitoring Techniques.