California’s Experience with Mosquitoes in Aquatic Wastewater Treatment Systems

The history of wastewater treatment ponds in California is directly linked to the state and federal Clean Water Grant Program. Two approaches will avoid mosquito problems in wastewater treatment ponds. One is to create conditions in the pond that are not attractive to mosquitoes or are not conducive to larval development as in original guidelines for oxidation pond design. The other approach is mosquito larvae control using chemical or biological methods after they have become established. Most treatment facilities will probably need to have a tailored program for mosquito prevention and control. When chemical or biological control agents do not adversely affect mosquito pathogens and predators, season-long mosquito control may be possible after only one or two treatments. Despite the challenges, mosquitoes can be controlled with careful planning and management of wastewater facilities. Mosquito breeding management must be included in the earliest planning stages and must be included in operating procedures after plants have come on-line.