Page 7 - Lake Roosevelt Forum 2020 Public Guide
P. 7
UPPER COLUMBIA VALLEY
Upper Columbia Valley Aerial Deposition Areas (ADAs) where Lead Risks Exceed Benchmarks
ADAs are at least 25 acres in size, and the soil is less disturbed due to infrequent human contact or development.
CANADA
WASHINGTON
Boundary
Columbia River
UPPER COLUMBIA VALLEY
Marble China Bend
Northport
WASHINGTON
Map of lead soil sampling results shows that ADAs exceeding EPA’s high benchmark tend to be closer to the Columbia River and the U.S.-Canada border. As one moves farther east or west in the upland areas, soil concentrations exceeding risk benchmarks decrease.
LEAD BENCHMARK
Low Medium High
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