JOHN ELIAS BALDACCI

GOVERNOR

STATE OF MAINE

DEPARTMENT OF AGRICULTURE, FOOD AND RURAL RESOURCES

BOARD OF PESTICIDES CONTROL

28 STATE HOUSE STATION

AUGUSTA, MAINE 04333-0028

SETH H. BRADSTREET III 

COMMISSIONER

HENRY JENNINGS

DIRECTOR

Disclosure Statement Regarding The Application of 

Aquatic Herbicides (including Pond Dyes) 

The Maine Board of Pesticides Control (BPC) and the Maine Department of Environmental Protection (DEP)

have requested that pesticide dealers present this statement to all persons who purchase an herbicide that is 

labeled for use in surface waters. The two agencies want to ensure that every purchaser is clearly aware of the 

restrictions on aquatic herbicides (including pond dyes) as outlined below. 

Permits Required for “Waters of the State” 

The DEP requires anyone applying any pesticide to “Waters of the State” to first obtain a Maine Waste 

Discharge License (WDL). Maine statutes define “Waters of the State” as: 

“...any and all surface and subsurface waters that are contained within, flow through, or under or 

border upon this State or any portion of the State, including the marginal and high seas, except such 

waters as are confined and retained completely upon the property of one person and do not drain into or 

connect with any other waters of the State, but not excluding waters susceptible to use in interstate or 

foreign commerce, or whose use, degradation or destruction would affect interstate or foreign 

commerce.” 

This means that only private ponds contained entirely on a single property and without an inlet or outlet can be 

treated without a permit. 

Purchase and Application of Aquatic Herbicides 

Persons wishing to purchase and apply an aquatic herbicide—except for the pond dyes listed below—must first 

obtain a pesticide applicator’s license from the BPC. Best Management Practices (BMPs) have been 

developed that must be followed by those planning to treat private ponds with any aquatic herbicide (including 

pond dyes)—see “Best Management Practices for The Application of Aquatic Herbicides in Private Ponds” 

below. 

Purchase and Application of Certain Pond Dyes 

Persons wishing to purchase and apply pond dyes such as Aquashade, Admiral or Pondmaster Blue (containing 

the active ingredients erioglaucine [Acid Blue 9] and tartrazine [Acid Yellow 23]) are exempt from applicator 

licensing requirements. However, while these products are exempt from licensing requirements, the requirement 

for obtaining a WDL still applies, if applicable (see “Waters of the State” definition above). 

Purchasers should be aware that the State has a policy of minimizing reliance on pesticides and that herbicides 

used to control common aquatic weeds may have adverse effects on the environment. Purchasers are therefore 

encouraged to learn more about aquatic weed identification and nonchemical control measures by visiting 

http://www.state.me.us/dep/blwq/topic/invasives/index.htm. 

Information on invasive aquatic plants, permits and aquatic herbicides may also be obtained by contacting the 

DEP at 207-287-3901. Information on pesticide applicator licensing may be obtained from the BPC at 207-287-

2731 or go to http://www.thinkfirstspraylast.org/cert/questions.htm.
Best Management Practices for The Application of 

Aquatic Herbicides in Private Ponds 

Effective: June 15, 2007 

Common algae and plants can thrive in private Maine ponds when ideal conditions are provided. Ample 

sunlight, fertilizers and nutrients from surrounding areas and—especially for algae—groundwater recharge can 

hasten growth, creating a nuisance that compromises recreation, aesthetics and other pond uses. 

Pond owners faced with algae or plant infestation may consider using products, namely pesticides, which claim 

to control these species. Maine laws place conditions on how these products may or may not be used because of 

the risks they pose to human health, as well as to nearby streams, wetlands, lakes or groundwater that are legally 

regarded as “Waters of the State.”

Pesticides that claim to kill or control vegetation in water—algae and other aquatic plants—are called aquatic 

herbicides. Pond dyes or colorants are aquatic herbicides that prevent algae and weed development by limiting 

light and restricting photosynthesis.

Generally, aquatic herbicides, other pesticides or any pollutant may not be discharged into any water of the state 

without a WDL from the DEP.

Further, the BPC restricts the sale and application of aquatic herbicides to BPC-licensed applicators. Initially 

this restriction also included pond dyes.

In March 2007, the BPC relaxed regulations affecting the sale and use of pond dyes only if used within a private 

pond contained on one person’s property. While BPC sale and use restrictions for other aquatic herbicides and 

DEP discharge licensing requirements remain in force, the private pond owner may now purchase and use BPCregistered pond dye products for private pond use. 

The rationale for easing rules on pond dye purchase and use is that these products are able to meet algae and 

plant control needs of private pond owners while posing minor risk to Maine’s aquatic habitats. 

Minor risk, however, is not the same as zero risk. Pond dye products can have biological and other 

environmental consequences in the event they escape from the pond and move into waters of the state. The DEP 

prohibits the discharge of any material to waters of the state that change the color, clarity, chemistry or 

temperature of the receiving waters without a WDL.

Therefore, application of pond dye products must be conducted in a manner that demonstrates the highest 

standards of conduct, namely in accordance with the BMPs. 

The following BMPs must be followed by both licensed and unlicensed pond dye users. Licensed pesticide 

applicators certified for aquatic vegetation control who intend to treat private ponds with any aquatic herbicide 

must also follow these BMPs. While close attention to these BMPs will prevent an illegal discharge in most 

cases, good judgment should always prevail. 
Maine BMPs for Use of Aquatic Herbicides In Private Ponds for 

Control of Algae and Other Aquatic Plants 

• Aquatic herbicides and pond dyes may be used without a WDL only under the following conditions: 

o Use of aquatic herbicides and pond dyes must not result in a discharge to groundwater or surface 

waters of the state (such as ponds, lakes, wetlands, streams and rivers). 

o Aquatic herbicides and pond dyes may only be used in private ponds contained wholly on a 

single property. 

o Aquatic herbicides and pond dyes may only be used in ponds that have no outflow while these 

products are active. 

o Aquatic herbicides and pond dyes may only be applied after any seasonal high water outflow has 

ceased. 

o Aquatic herbicides and pond dyes may only be used in ponds that generally have a seasonal high 

water outflow if: 

 there is no defined channel exiting the pond such as a drainage swale or a mineral bottom 

channel; 

 there is no year-round surface water body (such as lakes, ponds, streams and rivers) 

within 100 feet down gradient of the pond; 

 any seasonal outflow does not occur as channeled flow, but occurs only across a dense 

vegetated area at least 50 feet in length, as measured along the gradient. 

o Aquatic herbicides and pond dyes may only be applied during the months of May, June, July and 

August. 

o Aquatic herbicides and pond dyes may only be applied after spring runoff and when the water 

level has stabilized or has been drawn down at least 6 inches below the point of discharge. 

o Aquatic herbicides and pond dyes should not be applied when weather forecasts predict 

significant rainfall during the five-day forecast period following application. 

o Aquatic herbicides and pond dyes must be applied at the minimum effective rate and in 

accordance with label instructions. 

For more information, contact the following: 

Robert Stratton 

Bureau of Land and Water Quality 

Maine Department of Environmental Protection 

State House Station 17, Augusta, ME 04333 

tel.: 800-452-1942, e-mail: robert.d.stratton@maine.gov

Henry Jennings 

Maine Board of Pesticides Control 

State House Station 28, Augusta, ME 04333 

tel.: 287-2731, e-mail: henry.jennings@maine.gov

John Jemison 

University of Maine Cooperative Extension Water Quality Office 

495 College Avenue, Orono, ME 04473 

tel.: 800-870-0270, e-mail: jjemison@umext.maine.edu