In Canada and the U.S., aquatic exposure to pesticides is modeled using field and waterbody models linked together using the Pesticide in Water Calculator (PWC v. 2.001). The field model is the Pesticide Root Zone Model (PRZM v. 5) (USEPA 2020). The waterbody model is the Variable Volume Waterbody Model (VVWM v. 1.02) (USEPA 2019). Currently, US and Canadian pesticide regulatory agencies do not have the ability to quantitatively model potential pesticide runoff reductions from vegetative filter strips (VFS), an area of non-crop (typically grass) vegetation designed to remove sediment and other pollutants from surface water runoff. In 2018, North Carolina State University’s Center of Excellence for Regulatory Science in Agriculture (CERSA) held a workshop, “Incorporating the benefits of vegetative filter strips into risk assessment and risk management of pesticides.” The workshop was organized by scientists from academia, government, and industry along with conservation experts and producers interested in evaluating VFS for reducing pesticide transport. A second workshop was held in September of 2020 where the mechanistic Vegetative Filter Strips Model (VFSMOD) was recommended in combination with PWC for quantitative mitigation of pesticides with VFS in current high-tier, long-term risk assessments.This document oninput parameter definitions, literature references, and sensitivity analyses of the parameters used in VFSMOD is the result of the discussions following the second workshop for reference in the application of the model.
