Early warning monitoring systems can be used to detect water quality changes and thus be able to take response actions such that public health and treatment systems are protected. For example, early warning systems can be incorporated into operational practices at the water plant to provide information to held decide on appropriate response actions to sudden changes in water quality. Potential responses may include one or more of the following:
- Increased monitoring and surveillance
- Spill cleanup
- Installation of protective booms or surface sprays near intakes
- Closing surface water intakes to let contaminants pass
- Repositioning intake position to a lesser or unimpacted location, if available
- Use of an alternate source of water supply
- Filling storage tanks prior to contamination reaching intake
- Enhanced water treatment (e.g., modify treatment process conditions such as using more coagulant for removal of particles, using additional disinfectant, and using greater amounts of powdered activated carbon)
- Shutting down water treatment plant
- Notification to public health agencies and the public, including public caution recommendations (e.g., for immuno-compromised) or issuing a boil water advisory
- Follow-up epidemiological studies
- No action
It is important to determine potential responses and response thresholds in advance of any potential contamination events. The principles of strong emergency contingency planning perhaps apply more to this component of an early warning monitoring system than to any other. Appropriate water supplier responses depend on the type and potential extent of contamination, projected risks (e.g., resulting effects on public health or treatment process efficiency), and characteristics of the affected population. Plans should be prepared in advance as well as possible.
Water utilities with CAFOs in their watershed that store large amounts of liquid animal waste should have a contingency plan developed and in place, and to make effort to be included on all spill-related call lists used by state or local spill response agencies. Good communication with local emergency spill response organizations and state environmental agencies will help to ensure utilities are informed of spill events, and to provide information vital to a coordinated response. Riverbank filtration, pre-sedimentation, off-stream storage, and other pre-treatment structures can provide utilities with more options when dealing with these events, particularly large, short term, accidental spills and releases.