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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Interested in our other Aquatic Pesticide permits?  Join our Aquatic Pesticide Permits email notification list for updates.

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. 

Permit reissuance

The release of the draft irrigation permit for comment is now expected in Summer 2022. Opportunities for public participation will include workshops and hearings during the public comment period.

We anticipate making a final permit decision in Fall 2022. If the permit is reissued, we anticipate an effective date of Fall or Winter 2022.

We hosted two online public listening sessions on Aug. 10, 2021, and Aug. 12, 2021. The slides from these presentations are available through the link below. For more information about these presentations, or about the permit reissuance in general, please contact Danielle Edelman at  

Listening Session 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 (products added to pesticides to improve their effectiveness or performance) and active ingredients consistent with other aquatic pesticide permits
  • Adding requirements that improve permittees’ communication with the public
  • New Environmental Impact Statement (EIS) to analyze effects of permit activities and alternatives


Summer 2022: Formal comment period on the draft permit and Environmental Impact Statement (EIS)
Fall 2022: Decision on reissuance
Fall/Winter 2022: 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 are accepted until the permit is reissued.