Irrigation System Aquatic Weed Control permit

The Irrigation System Aquatic Weed Control (ISAWC) permit allows the regulated use of aquatic pesticides, marker dyes, and nutrient inactivation products to control the growth of aquatic plants and algae within irrigation systems, helping them maintain the capacity to convey water.

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The Irrigation System Aquatic Weed Control permit was last issued in 2012 and is currently under administrative extension.

The current administrative extension allowed us to develop an environmental impact statement (EIS) to assess permitted chemicals allowed for use within irrigation systems and to identify mitigation actions to reduce the potential of adverse environmental impacts. 

Permit reissuance

We are pleased to announce that the draft Irrigation System Aquatic Weed Control general permit and draft Environmental Impact Statement is available for public comment. We invite comments on the draft permit documents and draft EIS beginning Jan. 18, 2023, until 11:59 p.m. on March 6, 2023. After the close of the comment period, we will publish a Response to Comments to address comments submitted during the public comment period.

General permit documents

Draft Environmental Impact Statement (DEIS)

How to provide comments

The comment period for the draft permit documents and the draft environmental impact statement will run simultaneously, however we have separate online comment links. Both comment periods are open Jan. 18, 2023, until 11:59 p.m. on March 6, 2023.

Comment online (preferred method):

By mail:
Danielle Edelman
Washington State Department of Ecology
PO Box 47696
Olympia, WA  98504-7696

In person: Comments are accepted during any of our public hearings

Workshop and hearings

During the workshop, we will explain the proposed changes to the permit and answer questions. We will also explain the key findings of the draft environmental impact statement. The hearing will begin after the public workshop and will end when public testimony is complete. During the hearing, you may give oral testimony on the proposed changes or the draft EIS. Written comments receive the same consideration as oral testimony.

We will host a workshop immediately followed by a public hearing on the following dates:

Feb. 21, 2023 – Webinar, 10:00 a.m.

Feb. 22, 2023 – Webinar, 5:30 p.m.

Changes to the permit we are considering include, but are not limited to:

  • Updating the permit to match current standards for aquatic pesticide permits.
  • Updating and clarifying reporting requirements.
  • New guidance on how to qualify for and maintain a reduced monitoring plan.
  • Allowing permittees to use new adjuvants (products added to pesticides to improve their effectiveness or performance) and active ingredients, consistent with other aquatic pesticide permits.
  • Adding a new chemical-tracking option to avoid the requirement to hold water back from closed side channels after a main canal treatment.
  • Adding requirements that improve permittees’ communication with the public.
  • New Draft Environmental Impact Statement (DEIS) to analyze effects of permit activities and alternatives.


January 2023 – March 6, 2023: Formal comment period on the draft permit and Environmental Impact Statement (EIS)
May 2023: Anticipated decision on reissuance
June 2023: Anticipated effective date for the final permit

Current permit documents

Apply for coverage

Due to the current administrative extension of the permit, no new applications for coverage will be accepted until the permit is reissued.