Zostera japonica management on commercial clam beds in Willapa Bay general permit
We issue coverage under this general permit when shellfish growers choose to use an aquatic herbicide (imazamox) to control the non-native eelgrass Zostera japonica on their commercial clam beds. This permit does not cover herbicide use on geoduck or oyster beds, or regulate physical or mechanical control methods. Zostera japonica is listed as a class C noxious weed because it can cause significant impacts on clam aquaculture and harvest for the shellfish industry in Willapa Bay. Read our blog to find out more about the Zostera japonica permit.
The current permit expired on March 3, 2025. The new permit is effective on May 2, 2025 and expires on May 1, 2030. Although the current permit has expired, it is still in effect until the new permit becomes effective.
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Permit documents
We are pleased to announce that we are reissuing the Zostera japonica Management on Commercial Clam Beds in Willapa Bay General Permit. A formal announcement was published in the Washington State Register on April 2.
- Current Permit (expired March 3, 2025, remains in effect until May 2, 2025)
- Fact sheet for the draft 2020 permit
Effective May 2, 2025
Public process
We invited public comments on the draft general permit documents beginning Nov. 21, 2024 through Jan. 14, 2025. We also held two workshops and public hearings, both online and in-person. During the workshops in December and January, we explained the proposed changes to the permit and answered questions before the public hearings began. Appendix C of the final fact sheet, linked above, shows our response to those comments.
Click the map to enlarge.
Documents from the draft 2025 public comment period
- Draft general permit
- Redline version of the draft general permit
- Fact Sheet for the draft general permit
- Comments on the draft
- Focus on: Controlling Zostera japonica on clam beds in Willapa Bay (2024)
- Small Business Economic Impact Analysis (2024)
- Environmental Impact Statement (2014)
Map of treatment areas
This map shows where treatments to control Z. japonica have been done between 2019 - 2023. An average of 82 acres of clam beds were treated each year during this time. The total area of Willapa Bay is around 80,000 acres, with approximately 8,000 acres covered by the native eelgrass Z. marina, and about 6,000 acres covered by the invasive eelgrass Z. japonica.
Related links
Contact information
Questions about permit implementation:
Shawn Ultican
Aquatic Pesticide Permit Specialist
shawn.ultican@ecy.wa.gov
360-870-3492
For technical assistance with applications, forms, transfers, termination, SAW, and WQWebPortal:
Eman Jabali
General Permit Administrator
aquaticpesticideperm@ecy.wa.gov
564-233-9135