WSR 09-21-085


[ Filed October 19, 2009, 11:04 a.m. ]

Department of Ecology to Modify the General Permit for

Aquatic Weed Control in Irrigation Systems

The Washington state department of ecology has made a preliminary determination to modify the general permit for irrigation systems. The permit covers entities that use pesticides to control aquatic weeds in irrigation systems. The department of ecology expects to modify the permit by March 2010. The department of ecology originally issued the general permit in 2008. It will expire in February 2013.

The permit covers irrigation districts and irrigation water suppliers who apply aquatic herbicides and algaecides in irrigation canals and ditches. Currently, sixteen irrigation districts are covered by the permit. The modification to the permit would allow the use of the pesticide endothall. Endothall is an alternative to acrolein, the herbicide that irrigation districts historically used but is being phased out.

We expect to complete the draft version of the permit modification and release it for public comment by January 2010. The proposed timeline for drafting the permit is:

January 2010 Public notice of draft permit
February 2010 Public hearing and end of the public comment period
March 2010 Issue final permit

A modification of a permit can be appealed pursuant to RCW 43.21B.310. Entities that are currently covered by the permit do not need to reapply for coverage under the modified permit.

The department of ecology will keep a mailing list to inform the public of significant stages in the modification of the permit, including notices of the draft permit, public hearings, and issuance of the permit. Information will also be posted on the department of ecology's web page at

To join the mailing list, to comment, or for more information, please contact Andrew Kolosseus, Washington State Department of Ecology, Water Quality Program, P.O. Box 47600, Olympia, WA 98504-7600, (360) 407-7543,

Washington State Code Reviser's Office