How to Manage Pests
Constructed treatment wetlands can provide cost-effective water quality treatment and may provide other benefits such as wildlife conservation, wetland habitat enhancement, and sites for public education and recreation. However, man-made wetlands used to treat municipal or agricultural wastewater as well as storm water often produce mosquitoes, which are a public health concern.
Design features that are thought to be necessary for water quality improvement, such as shallow water and dense emergent vegetation, can cause significant mosquito production. Because many bird species are reservoirs for viral pathogens that cause diseases in humans and domesticated animals, the attraction of large numbers of birds to constructed wetlands also increases the risk of transmission of mosquito-borne viral infections to susceptible bird populations living near human residences and to humans and companion animals. The potential for conflict between wetland operators or managers and agencies charged with protecting public health is typically highest near areas of residential development and in arid regions where mosquito populations are naturally low.
This publication discusses how the design and operation of surface-flow wetlands constructed primarily for water quality improvement can contribute to issues related to high populations of mosquitoes. Subsurface-flow wetlands, another type of constructed treatment wetland, are not discussed here. Surface-flow wetlands most often appear similar to a marsh containing emergent vegetation. Many of the recommendations discussed here also apply to man-made wetlands intended for uses other than water quality improvement. Incorporating design features to minimize mosquito production can significantly decrease mosquito abundance, lower the costs of mosquito control, and may lessen legal liability.
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