**DEPLW0704B**

Background **Mosquitoes and other biting insects are unarguably a nuisance in Maine. However, they also**  **occupy an important part of the ecosystem, providin g a hard-to-replace food item for other insects,**  **amphibians, fish, and birds. Efforts to chemically control insects have the potential to cause far**  **reaching environmental effects. Therefore, when co nsidering using pesticides, you must proceed**  **cautiously to avoid causing adverse impacts to aqua tic life and habitats.** 

**Maine state law governs aquatic pesticide applicati ons. If the area to be treated is a water of the**  **State or if the treatment will potentially result i n a discharge to a water of the State, you must fir**  **st obtain a Maine Waste Discharge License (WDL).** 

Applicable definitions and citations from rule and law **► Aquatic pesticide is defined as any substance app lied in, on or over waters of the State or in such**  **a way as to enter those waters for the purpose of i nhibiting the growth or controlling the existence**  **of any plant or animal in those waters (Department rule 06-096 CMR Chapter 514).** 

**► No person may directly or indirectly discharge or cause to be discharged any pollutant to a water**  **of the State without first obtaining a license from the Department of Environmental Protection**  **(DEP) (State law 38 MRSA, §413(1)).**

**► “Waters of the State means any and all surface an d subsurface waters that are contained within,**  **flow through, or under or border upon this state or any portion of the State...except such waters as**  **are confined and retained completely upon the prope rty of one person and do not drain into or**  **connect with any other waters of the state... .” (38 MRSA, §361-A(7)). By definition, waters of**  **the State include streams, rivers, lakes, ponds, marine**  **waters, wetlands, and groundwater. In Maine,**

**almost all wetlands are connected to either surface or ground waters, and some are connected to** 

**both.**

Chemical and biological agents **Various chemical and biological agents are marketed for control of mosquitoes. Chemical**  **pesticides are not selective and have the potential to impact other species. Bacterial pesticides are**  **developed to impact species with specific propertie s, but may still impact more species than desired**  **if improperly used. For example, the bacterial pes ticides Bti (**  Bacillus thuringiensis, **subspecies**

israelensis **) and Bs (** B. sphaericus **) work on alkaline pH guts, which are found in mosq uitoes, black**  **flies, and some non-biting midges. Other bacterial agents may also affect butterflies and moths.**  **Application of either type of pesticide to a water of the State requires a WDL. Pesticide**  **applications to dry land with the potential to reac h waters of the State during the time the pesticide**  **is active will also require a WDL pursuant to DEP R ules, Chapter 514.** 

Waste discharge license (WDL) rule criteria **The Chapter 514 rules provide the following criteri a for receiving a WDL to apply a pesticide to a** 

**water of the State:** 

# DEP FACT SHEET

Aquatic Pesticide Applications for Mosquito Control

Date: **June 2008** Contact: **Bob Stratton (207) 287-3901 or** 

**Toll Free 1-800-452-1942 June 1**  **6 , 2008 DEPLW0704B** 

**A. The pesticide must be registered for the intende d use by the U.S. Environmental Protection**  **Agency (EPA) and the Maine Department of Agricultur e, Food and Rural Resources’ Board of**  **Pesticides Control (BPC). B. The applicant or agent must be licensed as a com**  **mercial applicator in the ‘Biting Fly and other Arthropod Vectors’ subcategory by the BPC.**  **C. The applicant must provide adequate protection f or non-target species.**  **D. The applicant must demonstrate (1) a significant need to control the target species and (2) that**  **the pesticide offers the only reasonable and effect ive means of control.**  **E. The application must not result in violations of State water quality laws (such as impairing a**  **waterbody so that it does not attain its designated classification).** 

**Items C, D, and E require SIGNIFICANT attention, as the DEP is concerned about the great**  **er environmental effects of mosquito treatments. The**  **DEP’s mission is to protect the quality, habitat, and designated uses of all waters of the State, the**  **refore WDL applications for mosquito control will be stringently scrutinized. Some activities, howev**  **er, can be conducted without DEP approval, as**

**noted below.**

Activities that do not require DEP approval **The DEP has determined that treatments using granul ar or solid forms of Bti or Bs under specific**  **conditions in high elevation (extreme tide) salt ma rsh pools, constructed ponds, and isolated**  **freshwater wetlands do not require a WDL. In each of these resources, there must be a presence of**  **mosquitoes and an absence of fish or other predator s that can control them. In the salt marsh pools,**  **the Bti or Bs must be placed immediately after pool flooding to enable its dissipation prior to the**  **next flood event. The ponds and isolated wetlands must be contained on one person’s property and** 

**have no connection to other surface waterbodies. A s an additional regulatory option, the DEP has**  **developed a General Permit for Aquatic Pesticides f or the Control of Mosquito-Borne Diseases.**  **Coverage under the General Permit requires qualifie d projects to meet the criteria of Chapter 514**  **above as well as specific conditions related to the title, but provides a more expedited process.** 

Other information **To discuss requirements for mosquito treatment proj ects or obtain application materials, contact**  **DEP’s Division of Water Quality Management at (207) 287-3901 or toll free 1-800-452-1942.**  **Also, visit www.maine.gov/dep/blwq/docstand/wastepage.htm**  **to view applicable rules or permit application materials (click on**  General Materials **for rules;** General Permits **; or** Municipal/Industrial **, then** Applications **, then** Aquatic Pesticides **for forms). See also the DEP’s**

**website www.maine.gov/dep/special_topics.htm**  **and click on** West Nile Virus **for additional information and links to other sources, including t**  **he DEP Fact Sheet on Mosquito Control, West Nile Virus, and EEE.** 

**For more information on pesticides and their regula tion and use, including requirements for**  **Commercial Pesticide Applicator’s licenses and vari ance requirements near waters of the State,**  **contact the Board of Pesticides Control at (207) 28 7-2731 or visit their website at:**  **www.maine.gov/agriculture/pesticides**

**.**