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.
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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, from 2002 through 2010, Seattle Public Utilities attempted to control knotweed using physical means, including covering with geotextile fabric and digging, but even small patches of knotweed are exceedingly difficult to control by physical means, and treating knotweed with herbicide has been found to be the only effective way to control large patches; and
WHEREAS, uncontrolled knotweed in 2010 covered nearly 18 acres of land in the Cedar River Municipal Watershed and was spreading at rapid rate, displacing native species, eroding stream banks, threatening water quality, and destroying biodiversity; 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, and two follow-up limited exceptions to the Secondary Use Policies were authorized by Ordinances 124191 and 124852 to continue to allow application of the herbicide imazapyr through December 31, 2015, and December 31, 2018, respectively; and
WHEREAS, Seattle Public Utilities' method of applying a one percent imazapyr solution to knotweed from midsummer to fall is in line with King County Noxious Weed Contr...
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