Zostera japonica eelgrass has been colonizing commercial clam beds in Willapa Harbor, making it difficult to grow and harvest clams. USFWS Photo

Herbicide permit for Willapa Bay updated with new scientific data

OLYMPIA – Based on new scientific research and data, the Washington Department of Ecology is updating an existing, active permit that allows commercial shellfish growers to continue to use the herbicide imazamox to control non-native eel grass in Willapa Bay.

The growers requested the permit from Ecology several years ago because the non-native eel grass, Zostera japonica, is a noxious weed that makes it difficult to grow and harvest clams.

When Ecology issued the permit in 2014, they required the growers to study and verify that a 10-meter unsprayed buffer around the treatment area adequately protects native eelgrass and water quality.

The scientific research and results came back showing that the application method is working as intended and confines the herbicide impact to the applied area. Ecology has updated the permit based on the new data.

Scientists from the National Oceanic and Atmospheric Administration, and state departments of Fish &Wildlife and Natural Resources reviewed the study data and did not recommend changes to the buffer.

According to the U.S. Environmental Protection Agency, imazamox is practically non-toxic for mammals, fish, birds and invertebrates. EPA does not believe it poses a hazard to public health in or on food products.

This permit is specifically tailored for commercial clam beds in Willapa Bay only.

Comment deadline extended

Because information in the fact sheet referring to an outside study incorrectly over-stated the application rate of imazamox to the test sites, Ecology extended the comment period for the Non-native Eelgrass Permit Modification for an additional 30 days. The new end of the comment period will be March 7.

More information on the correction is available at: http://www.ecy.wa.gov/programs/wq/pesticides/eelgrass/docs/2016mod/ErrataZjFactSheetAddendum.pdf