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Water Quality Program

Frequently Asked Questions

Note that the information in this FAQ was last updated November of 2012. The information here may be out of date.

Q. Why is the Department of Ecology (Ecology) developing a permit for the control of Zostera japonica?

A. Commercial shellfish growers requested a permit for the use of imazamox to help them manage the growth of Zostera japonica on their shellfish beds. According to the growers, these beds were historically sand/mud flats and just recently Zostera japonica has been colonizing these beds making it difficult to grow clams in these areas. Several growers have indicated that they have abandoned beds and had to lay off staff because of this. The growers want to use the aquatic herbicide imazamox to remove Zostera japonica from their commercial clam beds. The only way that they can legally use imazamox for this purpose is under a National Pollutant Discharge Elimination System (NPDES) permit issued by Ecology.

Q. Is Ecology going to require an Environmental Impact Statement (EIS) for this action?

A. Yes. Ecology is requiring an EIS before issuing the draft permit and we have asked the growers to prepare the draft EIS. In the EIS, Ecology has asked the growers to explore other non-chemical methods of removing Zostera japonica and the no-action (not doing anything) alternative, as well as evaluating the impacts of the use of imazamox. The growers contracted with a consultant to prepare a risk assessment for the use of imazamox and will use this risk assessment to help evaluate the impacts of the herbicide on the estuary. The draft EIS will be available for public review and comment along with the draft permit.

Q. Why does Ecology consider Zostera japonica an invasive weed?

A. In 2012 the Washington State Noxious Weed Control Board (WSNWCB) listed Zostera japonica as a class C noxious weed on commercially managed shellfish beds only. For more information on the WSNWCB go to: http://www.nwcb.wa.gov/

Q. Does the imazamox formulation Clearcast contain adjuvants or surfactants?

A. No. There are no adjuvants or surfactants proposed to be used for the application of imazamox for Zostera japonica removal.

Q. Has there been any review of the inert ingredients of Clearcast?

A. The company that makes Clearcast has disclosed the proprietary inert ingredients to Ecology. We had an environmental toxicologist from the Department of Agriculture and a human health toxicologist from the Department of Health review the inert ingredients. They did not express any toxicological concerns about the inert ingredients.

Q. Will commercial shellfish growers be required to treat shellfish beds for Zostera japonica?

A. No, Ecology would not require treatment of Zostera japonica beds. If the permit proceeds, each grower will apply individually for permit coverage to treat their commercial clam bed in Willapa Bay.

Q. Would the proposed permit allow treatment on all shellfish beds in Willapa Bay?

A. No. Only commercially managed clam beds, excluding geoduck, would qualify for coverage under the proposed permit.

Q. What precedence does Ecology have for allowing the use of pesticides in Willapa Bay?

A. Historically Ecology has issued permits that allow the use of pesticides in estuaries. Examples include the use of imazapyr and glyphosate for the control of Spartina spp. (multiple species) eradication and the use of carbaryl for the control of burrowing shrimp.

Q. How would native eelgrass (Zostera marina) be protected in commercial clam beds that are permitted for treatment of Zostera japonica?

A. Ecology is concerned about potential harm to native eelgrass beds that are near treated commercial beds. We will propose buffers to protect these beds, and monitoring to determine how effective these buffers will be. Buffer distances will be based on previous monitoring conducted by Washington State University Extension scientists under experimental use permits issued by the Washington State Department of Agriculture. Native eelgrass tends to grow at lower tidal elevations than Zostera japonica and can sometimes be found in depressions on the commercial bed. Ecology will only allow spraying to occur on Zostera japonica when it is dewatered on a low tide. The Zostera japonica will be exposed, but the native eelgrass in the depressions will contain water that will help protect native eelgrass from the effects of the chemical. Ecology does anticipate some impacts to native eelgrass on the sprayed commercial bed.

Q. What happens if monitoring shows detrimental effect on native eelgrass beds adjacent to treatment sites?

A. Ecology can terminate a permit if it decides that there are significant detrimental impacts to non-target organisms. Ecology reissues general permits once every five years or less. That gives the agency a chance to make modifications based on monitoring, input from user groups and other interested parties. Ecology can also modify a permit to make changes to permit language (this triggers a public comment period). Because of the issues surrounding this permit (potential impacts to native eelgrass); Ecology expects to have substantive oversight with monitoring and data interpretation.

Q. Why is the proposed permit only covering commercial clam beds and not other aquaculture?

A. It was our understanding that the greatest impact to commercial shellfish was occurring in Willapa Bay and to commercial clam operations. We also understood that there were concerns from growers that Zostera japonica could cause problems in some oyster growing grounds and in areas other than Willapa Bay, but these problems were not yet occurring. When Ecology went out for public comment about allowing the treatment of commercial shellfish beds statewide, we had very strong concerns expressed by natural resource agencies and other interested parties that any permit that we issued should start small (for example, on a pilot scale) and that we should evaluate impacts before considering expanding the permit to other areas. Therefore, Ecology decided to limit this first permit to just Willapa Bay and to just commercial clam beds. This will allow us to monitor and evaluate impacts on a smaller scale.

Contact Information:

Nate Lubliner
Washington State Department of Ecology
P.O. Box 47600
Olympia, WA 98504-7600
Email: Nate.Lubliner@ecy.wa.gov
Phone: 360-407-6563