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.

Join our irrigation system aquatic weed control listserv

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

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


Summer 2021: Informal Listening Sessions held
Fall 2021: Formal Public Comment period on the draft permit
Winter 2022: Decision on permit reissuance

Permit reissuance

Following the timeline above, we expect the draft permit in Fall 2021. At that time, we will have an additional opportunity for public participation with a formal public comment period.

We hosted two online public listening sessions on Aug. 10, 2021, and Aug. 12, 2021. These public listening sessions were an opportunity for Ecology to update interested parties, stakeholders, and other members of the public on planned changes for the permit (see list below) and to answer questions about the draft permit and Environmental Impact Study (EIS). The permit writer took note of any suggested changes or additions to the permit. These listening sessions were not public hearings, and comments on the draft permit during the sesssion are not recorded for the public record. 

Please contact the permit writer if you have any questions about the presentation:
Listening Sesion PowerPoint Presentation

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 and active ingredients consistent with other aquatic pesticide permits.
  • Adding requirements that improve permittees’ communication with the public.

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.