Under R 323.1097 of the Michigan Water Quality Standards the Water  is responsible for approving projects where pesticides are applied to surface waters of the state. Surface waters of the state are defined as the Great Lakes and their connecting waters, inland lakes, rivers, streams, impoundments and open drains, and other surface bodies of water within the confines of the state. Vernal woodland pools, roadside ditches, and wetlands are surface waters of the state.

In addition, any water treatment additive (WTA) that is discharged to a surface water of the state from an National Pollutant Discharge Elimination System (NPDES) permitted discharge requires prior review and approval by the WRD.  Pesticides used for controlling mosquito larvae in waters discharged under NPDES permits are considered WTAs.   Requests to perform pesticide treatment in wastewater treatment systems and catch basins covered by an NPDES permit must originate from the permittee and be made under the Water Treatment Additive approval process.

Integrated Pest Management (IPM) is the most appropriate approach for controlling mosquito populations and reducing the risk of infectious diseases like West Nile Virus (WNV).  An IPM approach includes a variety of techniques including the following:  education and outreach, surveillance of the insects, source reduction to reduce the opportunity for mosquito breeding, larviciding (when necessary) to kill the preadult stages of mosquitoes, and adulticiding (when necessary) to kill any remaining adults that were not killed by the larvacide in order to further reduce the breeding population.

Culex pipiens is the freshwater mosquito species most likely to carry the WNV.  This species is often associated with urban environments.  Its natural habitat is tree holes that are often filled with water and organic matter.  Any feature that replicates this natural habitat such as rain filled containers, empty flower pots, children's stagnant swimming pools, and abandoned tires will likely provide habitat for this mosquito species.

The most effective way to reduce mosquito breeding opportunities is to reduce and eliminate the source of breeding conditions.  This can be accomplished by eliminating the water in containers, empty flower pots, unused children's swimming pools, water-filled abandoned tires; changing the water in bird baths around the home once a week; and cleaning clogged eaves troughs to allow free flow of runoff.  Urban areas and "container" habitats should be targeted for source reduction of mosquitoes rather than wetland areas and other surface waters of the state.  The filling or draining of surface waters of the state are not acceptable measures for reducing mosquito breeding habitat. Further, filling or draining wetlands and other surface waters of the state is ineffective for control of the WNV because the most common mosquito carrier of the virus is associated with urban, rather than natural environments.  Such measures may also require state and federal permits.  Even after "draining," a wetland may hold water from flooding, rainfall, or snowmelt in low spots and subsequently produce more mosquitoes than natural wetlands.  The filling of wetlands may force water to flow elsewhere, creating flooding or additional wetlands.