Aquatic Pesticides

The application of pesticides onto Delaware surface water requires a permit from the Department of Natural Resources and Environmental Control (DNREC). Permits for this activity are part of the National Pollutant Discharge Elimination System (NPDES).

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Lydia Smith


In 2009, the U.S. Sixth Circuit Court determined that the application of biological pesticides and chemical pesticides with residuals to waters regulated under the provisions of the federal Clean Water Act (CWA) must be regulated by a NPDES permit.

In 2012, DNREC adopted the Regulations Governing the Discharges from the Application of Pesticides to Waters of the State as Subsection 9.8 (PDF) of the Regulations Governing the Control of Water Pollution (7 DE Admin. Code 7201).


The regulations cover discharges of biological pesticides and chemical pesticides that leave a residue from the following pesticide use patterns: mosquito and other flying insect pest control, weed and algae control, animal pest control, and forest canopy pest control.


DNREC has issued a NPDES General Permit for the application of Aquatic Pesticides: NPDES Permit Number DE 0051241.


DNREC offers an electronic reporting system for the Aquatic Pesticide program. The Electronic Notice of Intent (eNOI) system helps those covered by general NPDES permits meet their reporting requirements. Learn more from a guide to creating accounts and generating submissions.

Those unable to comply with the electronic reporting requirement should contact Lydia Smith, at 302-739-9946 or

Questions and Answers

What Are Waters of the State?

“Waters of the State” or “State Waters” means all water, on the surface and under the ground, wholly or partially within, or bordering the State, or within its jurisdiction including but not limited to:

  1. Waters which are subject to the ebb and flow of the tide including, but not limited to, estuaries, bays and the Atlantic Ocean;
  2. All interstate waters, including interstate wetlands;
  3. All other Waters of the State, such as lakes, rivers, streams (including intermittent and ephemeral streams), drainage ditches, tax ditches, creeks, mudflats, sand flats, wetlands, sloughs, or natural or impounded ponds;
  4. All impoundments of waters otherwise defined as Waters of the State under this definition; and
  5. Wetlands adjacent to waters (other than waters that are themselves wetlands) identified in the above four statements.

Although waste and stormwater treatment systems or waste storage structures including, but not limited to, treatment ponds or lagoons designed to meet the requirements of the Clean Water Act (other than cooling ponds which otherwise meet the requirements of this definition) are not considered to be “Waters of the State”, coverage will be required if they are determined to discharge into Waters of the State.

Who Needs to Get a Permit?

Operators required to get a permit include:

  1. A private applicator who purchases and applies “restricted use” pesticides;
  2. A commercial applicator (for hire) who uses any pesticides on other’s property in exchange for compensation; or,
  3. A commercial applicator (not for hire) who uses any pesticides as part of their job duties.

The pesticide certification classes that will apply include: Forestry (02), Aquatic (5A), Mosquito (5C), and Right of Way (06).

Where do I get a Permit?

Permit coverage can be obtained, free of charge, by creating an account on DNREC’s electronic reporting system and submitting an eNOI.

An eNOI should be filled out by:

  1. Any entity who performs the application of pesticides; or
  2. Any entity who has day-to-day control of the application (i.e. they are authorized to direct workers for hire to carry out those activities).

Permit coverage is valid up to a period of five years. A new NOI must be submitted within 30 days if an operator who has previously submitted an NOI undergoes a name change or if there is a change in ownership. Changes in operations including the change in active ingredients for products used, or change in size of Pest Management Area, as indicated on the NOI, will require a new NOI.

Who Must Develop a Pesticide Discharge Management Plan (PDMP)?

A PDMP must be developed for all state government entities, any operator that serves a population of more than 10,000, or a private enterprise that exceeds the Small Business administration size standard as identified at 13 CFR 121.201 (size standards set by North American Industry Classification System codes, varies by industry type). PDMPs are kept with the operator and are not required to be submitted to the Department. Please refer to the regulations in entirety for the mandated contents of the PDMP.

Who is Required to Keep Records, and for How Long?

Operators must keep written records covered under this regulation for five years. Please refer to the entire regulation, subsections – for the list of records.

What Must Be Sent to the Department?

Operators utilizing the electronic reporting system must submit a signed copy of the Electronic Signature Agreement form prior to account authorization and data input.

Immediately notify the Department of spills and leaks by calling the Spill Notification 24-hour Hotline: (800) 662-8802. Within 30 days of a reportable adverse incident to the health of humans or the environment, operators must provide a written report of the adverse incident to the Department. Please refer to the regulations, in full, to see the definition of Adverse Incident.

PDMPs are not to be submitted to the Department but must be kept with the operator. Only those operators who are required to develop a PDMP will be required to submit annual reports. The annual report must be submitted no later than February 1 of the following year for all pesticide activities covered under this subsection occurring the previous calendar year.