CITY OF SEATTLE
ORDINANCE __________________
COUNCIL BILL __________________
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AN ORDINANCE relating to the Cedar River Municipal Watershed; amending the Secondary Use Policies, adopted by Ordinance 114632, to provide for the limited application of the herbicide imazapyr to treat invasive knotweed species; and ratifying and confirming certain prior acts.
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WHEREAS, the Cedar River Watershed Secondary Use Policies, adopted by Ordinance 114632, include a moratorium on herbicide use to prohibit the routine broadcast application of herbicides for control of roadside vegetation in lieu of brushing, and invasive plant species were not a consideration in watershed land management practices when these Policies were adopted in 1989; and
WHEREAS, in 2010 uncontrolled knotweed covered 18 acres in the Cedar River Municipal Watershed, displacing native plants, eroding stream banks, threatening water quality, and spreading rapidly without any effective means of control; and
WHEREAS, on August 6, 2010, a limited exception to the Secondary Use Policies was authorized by Ordinance 123365 to allow the application of the herbicide imazapyr to control or eradicate knotweed species in the Cedar River Municipal Watershed through December 31, 2012, providing Seattle Public Utilities an efficient and cost-effective control strategy for the first time; and
WHEREAS, imazapyr inhibits an enzyme found only in plants, and the U.S. Environmental Protection Agency rates imazapyr as being relatively non-toxic to birds, mammals, fish, and invertebrates, and a Washington State University toxicologist found the risk to water quality to be nil; and
WHEREAS, three follow-up limited exceptions to the Secondary Use Policies were authorized by Ordinances 124191, 124852, and 125813 to continue to allow application of the herbicide imazapyr through December 31, 2015, 2018, and 2021, respectively; and control efforts have successfully reduced knotweed coverage, resulting in the reduction of herbic...
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