Aquatic Plant & Algae Management General Permit

We issue the Aquatic Plant and Algae Management (APAM) General Permit to allow chemical treatments for the management of aquatic noxious weeds, native nuisance plants, and algae. These chemicals are limited to a specific list of aquatic-labeled herbicides, algaecides, biological water clarifiers, adjuvants, marker dyes, shading products, and phosphorus sequestration products. They can be used directly into fresh water (lakes, streams, and rivers) or along shorelines, roadsides, dikes/levees, and ditch banks.

The current permit went into effect on April 21, 2021, and expires on March 21, 2026.

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We've updated our sign template to use more icons to help applicators warn people about any restrictions. 

Current permit documents

Permit reissuance

The draft general permit, fact sheet on the draft general permit explaining the legal and technical basis for the permit, economic impact analysis, a copy of the proposed application for coverage, and instructions for how to comment, are now available. The public is invited to review and comment on the draft general permit from 9 a.m. Sept. 10, 2025, through 11:59 p.m. Oct. 24, 2025. Ecology staff will host two virtual public meetings and hearings on the draft permit.

After the public comment period closes, we will publish a Response to Comments as an appendix to the fact sheet to address the public comments submitted. A formal public notice was published in the Washington State Register on Sept. 3, 2025. We also published a blog with some highlights of the proposed changes to the permit. 

Changes we are proposing

  • Revising monitoring requirements around dissolved oxygen and some types of treatments to reduce phosphorous
  • Clarifying treatment timing windows and the process to modify them
  • Increasing flexibility around when some aquatic herbicides can be used, based on more detailed ecotoxicity data
  • Adding another formulation of the aquatic herbicide triclopyr, and a new formulation of a lanthanum-based phosphorous control product*
  • Updating permit language to be consistent with current state and federal laws

*Note: A supplemental EIS that includes information on these products is being prepared and will be finished prior to issuing the final APAM permit.

Public involvement

Ecology will accept comments on the draft permit from 9 a.m. Sept. 10, 2025, through 11:59 p.m. Oct. 24, 2025. Comments should reference specific permit text when possible.

You can submit comments in the following ways:

  • Submit comments online (preferred)
  • By U.S. mail (postmarked by Oct. 24, 2025)
    Shawn Ultican
    WA Department of Ecology
    PO Box 47696
    Olympia, WA 98504-7696
  • At our public hearings

Public meetings and hearings

During the comment period we will host two online public meetings and hearings where we will explain the proposed changes to the permit and answer questions prior to the formal hearings. The public hearings provide opportunity for you to give formal spoken testimony on the proposed draft permit. The hearings begin immediately following the meetings and conclude when public testimony is complete. Spoken testimony will receive the same consideration as written comments.

Next steps 

After the comment period closes, we will review and consider all comments received. Then we will publish a Response to Comments as an appendix to the fact sheet and make a final decision on permit issuance. We expect to make a decision on the final general permit in early 2026.

Anticipated timeline

September and October 2025: Formal public comment period on the draft permit
October 14 & 16, 2025: Formal public hearings
Early 2026: Decision on reissuance
March 21, 2026: Current permit expires 

Permittee resources 

Permit documents

View and download permit documents.

Washington Department of Fish and Wildlife's Aquatic Pesticides Map Tool (Treatment Timing Windows)

Map shows specific locations where use of aquatic herbicides is subject to different timing restrictions to protect fish and other priority species. Click image to go to WDFW's map.