PRZM-GW (Pesticide Root Zone Model for GroundWater) is a Water Model that is used as a screening-level and refined tool for risk assessment purposes. In general, PRZM-GW provides conservative estimates of pesticide concentrations in groundwater, but it also allows for region specific scenario development in cases where refined drinking water assessments are needed.
Estimation of pesticide concentrations in groundwater is an important consideration of the exposure assessment in the pesticide registration process. For this reason, Canada and the United States combined efforts as part of the North American Free Trade Agreement (NAFTA) to develop a harmonized groundwater modeling protocol. This effort included the development of a common conceptual groundwater modeling scenario for regulatory purposes designed to be protective of even the most vulnerable drinking water supplies. Nineteen existing modeling programs were screened as candidate programs to implement the conceptual model.
PRZM was selected as the NAFTA regulatory tool to implement the conceptual model because of ease of use and in-house expertise required for maintenance.
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PRZM-GW Version 1.07 - Support Document - Identification and Evaluation of Existing Models for Estimating Environmental Pesticide Transport to Groundwater (PDF)(71 pp, 2 MB)
DRAFT FINAL REPORT of NAFTA Projects for Identification and Evaluation of Existing Models for Estimating Environmental Pesticide Transport to Groundwater. PRZM was selected as the NAFTA regulatory tool to implement the conceptual model because of ease of use and in-house expertise required for maintenance.