Washington state officials have approved an agreement that will prohibit oyster growers from spraying a dangerous neonicotinoid pesticide to kill native burrowing shrimp in Willapa Bay and Grays Harbor. Neonicotinoids are a leading cause of pollinator declines and are also linked to large-scale declines of birds, fish and bats because of their harmful impacts on aquatic invertebrate.

The state Pollution Control Hearings Board finalized the agreement last week. The four conservation groups that intervened in support of the state’s 2018 denial of a permit to annually apply imidacloprid on up to 500 acres of Willapa Bay and Grays Harbor support the agreement.

The agreement between the Washington Department of Ecology and the Willapa-Grays Harbor Oyster Growers Association includes resources to study and monitor the impacts of burrowing shrimp on commercial oyster and clam harvesting operations in the two bodies of water.

“Willapa Bay and Grays Harbor are unique and fragile places, and we’re happy Ecology listened to the scientists who study these poisons and their effects on ecosystems,” said Andrew Hawley with the Western Environmental Law Center. “Some oyster and clam growers have successfully achieved a balance between the shrimp and their farmed shellfish without use of dangerous pesticides, and that should be model going forward.”

“Commercial shellfish aquaculture should not sacrifice clean water or the health of our marine habitats, and we will continue to work to protect our bays and shorelines from the use of toxic pesticides,” said Amy van Saun, senior attorney with Center for Food Safety.

The Center for Food Safety, Western Environmental Law Center, Coalition to Protect Puget Sound Habitat and the Center for Biological Diversity had intervened in the case to keep the harmful pesticide imidacloprid out of these ecosystems.

While the use of imidacloprid will be prohibited by the terms of the settlement, the agreement allows consideration of spraying alternative chemicals and includes no commitment preventing oyster growers from requesting a permit for imidacloprid use in the future.

“Our beautiful coastline is no place to spray a dangerous pesticide that is notorious for contaminating water throughout the country,” said Nathan Donley, an Olympia-based senior scientist at the Center for Biological Diversity. “This important agreement will put an end to the disastrous plan to spray imidacloprid in some of our state’s most important and fragile waters.”


Washington researchers’ risk assessment determined that spraying imidacloprid on oyster beds has “immediate adverse, unavoidable impacts to juvenile worms, crustaceans, and shellfish to the areas treated… and the nearby areas covered by incoming tides…” This includes the commercially important Dungeness crab, which is also killed by imidacloprid, as are the native burrowing shrimp targeted by the shellfish growers’ association.

In 2015 the state granted a request by shellfish growers to spray imidacloprid but the permit was withdrawn after public outcry. In 2016 the growers’ association again applied to spray imidacloprid — never previously approved for aquatic use — onto shellfish beds to kill burrowing or ghost shrimp, a native species that growers say harms their bottom line.

Ecology denied that permit and the Growers Association appealed the denial to the Pollution Control Hearings Board.


Andrew Hawley, Western Environmental Law Center, 206-487-7250,

Amy van Saun, Center for Food Safety, 791-271-7372,

Laura Hendricks, Coalition to Protect Puget Sound Habitat, 253-509-4987,

Nathan Donley, Center for Biological Diversity, 971-717-6406,

Skip to content