Document ID: EPA-HQ-OPP-2007-0934-0018
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2008-01-07T05:00Z

Statistical analysis of the representativeness of the watersheds
selected for monitoring:  The Atrazine Ecological Monitoring Program
identified 1172 watersheds that were in the upper 80th percentile of
potential vulnerability to atrazine runoff, and selected a
representative pool of 40 subwatersheds for monitoring.   EPA has asked
the Panel to consider the appropriateness of identification of the pool
of potentially vulnerable watersheds and selection of the representative
monitored subwatersheds (Charge Question # 6).  The enclosed document
statically assesses the characteristics of the watersheds (WARP scores,
atrazine use, and other characteristics that render a watershed
vulnerable to potential atrazine runoff), and concludes that the sample
size of 40 is representative of the 1,172 most vulnerable watersheds.