Water Quality photo identifier

Water Quality Program

Willapa Bay - Grays Harbor
Burrowing Shrimp Control - Imidacloprid

After multi-year public process including preparation of an Environmental Impact Statement, Ecology issued a water quality permit for the use of Imidacloprid to control burrowing shrimp in Willapa Bay and Grays Harbor in April 2015. On May 3, 2015, the growers asked Ecology to withdraw the permit in response to strong public concerns.

Ecology agreed and cancelled the permit on May 4, 2015, effectively terminating commercial use of Imidacloprid on shellfish beds. Read the news release

2016 Process to control Burrowing Shrimp using Imidacloprid

On Jan. 8, 2016, a group of about a dozen oyster growers from the Willapa Grays Harbor Oyster Grower Association applied for a new pesticide permit for Imidacloprid to control burrowing shrimp. They propose treating less acreage than the previous application (500 acres in the two bays, as opposed to 2,000) and spraying from boats and/or ground equipment rather than from the air.

This new, independent permit application will go through the normal regulatory process. To date, Ecology has yet to receive complete sediment impact zone applications: one for Willapa Bay and one for Grays Harbor. Ecology has notified the growers of areas needing to be addressed to complete the application.

After a complete application is received, it will trigger public notice that Ecology will begin working on the permit review process. This process will include Ecology’s review and public involvement opportunities. Ecology will respond to public comments on the draft water quality permit, the draft sediment impact zones, and the draft supplemental environmental impact statement before any decision is made.

Environmental review process

Given the information Ecology has received to date, we have determined the proposal is likely to have significant adverse environmental impacts. Therefore, we have issued a “Determination of Significance” in the SEPA register.

We will move forward with the development of a Supplemental Environmental Impact Statement, and the adoption of the Final Environmental Impact Statement from the 2015 permit process, taking new information into consideration. This information includes new available science, change in spraying acreage and method, and information from a draft U.S. Environmental Protection Agency (EPA) ecological and human health risk assessment on imidacloprid, which is scheduled to be released in December 2016.

2016 Permit and SIZ Documents:

To stay informed on opportunities to comment on this process, please join our Aquatic Pesticide Permit ListServ.


Derek Rockett
Email: derek.rockett@ecy.wa.gov
Washington State Department of Ecology
Water Quality Program, Permit Writer
Southwest Regional Office
PO Box 47775
Olympia, WA 98504

2015 Permit and SIZ Documents

Oysters in basket after harvest

Aquatic Pesticides Contacts

Aquatic Pesticide Permit ListServ

Focus Sheet: Control of burrowing shrimp on shellfish beds in Willapa Bay and Grays Harbor