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Water Quality Program

Proposed Individual Permit for the Control of Burrowing Shrimp using Imidacloprid on Commercial Shellfish Beds in Willapa Bay and Grays Harbor

The Willapa/Grays Harbor Oyster Growers Association (the Association) has submitted an application to the Washington State Department of Ecology (Ecology) for an NPDES permit to allow the application of imidacloprid in an area limited to Willapa Bay and Grays Harbor. Imidacloprid is a pesticide used to control burrowing shrimp (Neotrypaea californiensis and Upogebia pugettensis) on commercial shellfish beds. The proposed NPDES permit would include specific conditions to regulate discharge of the pesticide.

new content image A 45-day public comment period on scoping for the draft Environmental Impact Statement began January 02, 2014 and ended February 15, 2014.

The purpose of scoping is to determine the "scope" or content of the EIS. Scope defines the environmental impacts and alternatives that need to be evaluated.

An open house and workshop was held on, Saturday, February 1, 2014. The purpose of the open house and workshop was to answer questions, provide information, and accept comments on the scope of the EIS.


Burrowing shrimp disrupt shellfish beds, which makes them unusable for aquaculture. Imidacloprid is a pesticide that disrupts the burrowing shrimps’ ability to maintain their burrows. Controlling the number of burrowing shrimp helps maintain the continued productive aquaculture of shellfish.

The Environmental Protection Agency has registered imidacloprid for use on commercial shellfish beds only in Willapa Bay and Grays Harbor for the control of burrowing shrimp.

Studies have been done on the impacts of imidacloprid application in Willapa Bay and Grays Harbor, as allowed by the Experimental Use section of the current NPDES permit for the pesticide carbaryl. These studies helped to inform the Risk Assessment done by Compliance Services International and funded by the Association. The Risk Assessment can be found here: Risk Assessment for Imidacloprid.

Contact for Proposed Permit:

Derek Rockett
Email: derek.rockett@ecy.wa.gov
Phone: 360-407-6697
Washington State Department of Ecology
Water Quality Program
Southwest Regional Office
PO Box 47775
Olympia, WA 98504
Oysters in basket after harvest.

Aquatic Pesticide NPDES Permit ListServ

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