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Use of Risk Assessment Information to Determine Treatment Buffer Widths.

Diana Perez, USDA Forest Service, Gifford Pinchot National Forest, Forest Fish Biologist, 10600 NE 51st Circle, Vancouver, Washington, 98682   360-891-5108, dperez@fs.fed.us

One-size fits all minimum buffer widths for herbicide applications tend to unnecessarily restrict options available or fail to minimize risk where appropriate.  Inherent herbicide properties such as persistence, mobility and toxicity to aquatic organisms vary, therefore, buffer widths should also vary.  Risk assessments and peer-review literature were used to group ten herbicides into low, moderate and high risk categories according to risk to aquatic organisms (fish, aquatic invertebrates, algae, and aquatic plants) based on herbicide properties.  Buffers were established to protect aquatic organisms for a variety of surface water bodies (wet and dry streams, wetlands, lakes, roadside ditches).  Higher risk application methods (i.e. broadcast vs. targeted spot-applications) and certain herbicides (picloram, triclopyr BEE) were determined that they needed larger buffers.