The MDEQ has regulatory jurisdiction over mosquito control strategies involving application of pesticides to surface waters of the state (Rule 97 of the Water Quality Standards, promulgated under Part 31, Water Resources Protection, of the Natural Resources and Environmental Protection Act, 1994 PA 451, as amended [NREPA]), facilities covered by National Pollutant Discharge Elimination System (NPDES) permits, and the draining and filling of floodplains and waters of the state, including wetlands.  The MDEQ is also responsible for enforcing the requirements that limit the potential for mosquito breeding habitat in stockpiles of scrap tires throughout the state.  Part 169, Scrap Tires, of the NREPA, provides for mosquito control at scrap tire collection sites.

Media attention of West Nile Virus (WNV) was elevated in 2002 due to fear of an epidemic outbreak.  Fifty-one people died in Michigan in 2002 from the WNV and other mosquito borne diseases.  The concern that an epidemic would occur led to mosquito control districts, cities, townships, villages, and individual homeowners seeking to use pesticides to control mosquito populations and reduce the threat of the WNV.  In 2003, two deaths due to WNV were reported throughout the state. No deaths were reported in 2004.

Under R 323.1097 of the Michigan Water Quality Standards the Water Division (WD) is responsible for approving projects where pesticides are applied to surface waters of the state and storm water catch basins.  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 NPDES permitted discharge requires prior review and approval by the Water Division.  Pesticides used for controlling mosquito larvae in waters discharged under NPDES permits are considered WTAs.  Requests to treat wastewater treatment systems and catch basins covered by a National Pollutant Discharge Elimination System (NPDES) permit with pesticides should 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.  

The following link details the MDEQ process for obtaining authorization to apply pesticides for mosquito control:  MDEQ Process for Obtaining Authorization to Apply Larvicides for Mosquito Control.