NPDES Permit for Aquatic Noxious Weed Control

WSDA holds the NPDES permit for use of herbicides to control aquatic noxious weeds in Washington State. The permit addresses use of herbicides to control marine weeds (such as Spartina), and freshwater emerged weeds (such as purple loosestrife).

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• Information on the Permit [external link]
• 2011 Annual Treatment Report [PDF 3MB]
• 2012 Freshwater Emergent Weed Monitoring Plan [PDF 141KB]
• 2012 Legal Notice for Spartina Treatments [PDF 1MB]

Environment Impact Statement Documents

• 1993 Ebasco Final Noxious Emergent Plant Management Environmental Impact Statement [PDF 22MB]
  • Element A Spartina: Distribution, Biology, and Ecology [PDF 2.3MB]
  • Element B Purple Loosestrife: Distribution, Biology, and Ecology [PDF 1.6MB]
  • Element C No Action: Efficacy and Impacts [PDF 3.5MB]
  • Element D Physical Control Methods: Efficacy and Impacts [PDF 4.3MB]
  • Element E Chemical Methods Only: Environmental Effects of Glyphosate and 2,4-D [PDF 6.9MB]
  • Element E Chemical Methods Only: Pesticide Characterization [PDF 6.7MB]
  • Element F Chemical Methods Only: Human Health Effects of Glyphosate [PDF 5.5MB]
  • Element G Chemical Methods Only: Human Health Effects of 2,4-D [PDF 6.8MB]
  • Element H Biological Control Methods: Efficacy and Impacts [PDF 2.6MB]
  • Element I Integrated Weed Management Alternative For Managing Noxious Emergent Plants [PDF 2.7MB]
  • Appendix J Dotted and Garden Loosestrife, Giant Hogweed, and Indigobush: Distribution, Biology, and Ecology [PDF 1.7MB]
  • Appendix K Emergent Noxious Weed Control Final Reports [PDF 11MB]
• 2003 Entrix Ecological Risk Assessment of the Proposed Use of the Herbicide Imazapyr to Control Invasive Smooth Cordgrass (Spartina spp.) in Estuarine Habitat of Washington State [PDF 14.1MB]
• 2009 AMEC Human Health and Ecological Effects Risk Assessment - Imazapyr Risk Assessment [PDF 4.8MB]