Design of early warning monitoring systems for source waters

Surface water systems may be vulnerable to sudden changes in source water quality as a result of accidental, intentional, or natural contamination from a variety of sources, including spills and storms. Utilities must respond quickly to these events in order to determine appropriate changes in treatment strategy and protect consumers from potentially harmful contaminants. Early warning monitoring systems can facilitate rapid response by using detection, event characterization, and communication to gather the information necessary to make sound decisions. This article discusses the characteristics, components, and design of early warning systems as well as existing and developing monitoring methods and still-needed research. Case studies provide snapshots of advanced early warning monitoring systems from around the world, in particular Europe and Asia. With a few notable exceptions, US experience with advanced early warning monitoring systems is limited, and most water supplies have little or no early warning system in place. When a contamination event occurs, time is of the essence to protect supplies and safeguard consumer health. Early warning monitoring not only cuts response time but also provides a cost-effective mechanism for reducing risks, boosting public confidence in the water utility, and promoting good practice and careful reporting on the part of dischargers. Using the information and framework provided here, utilities can begin developing their own early warning monitoring systems, thus ensuring that when water quality is endangered, they won't be caught flatfooted.