Table 23. Concentrations exceeding freshwater-quality criteria for trace elements in stormwater runoff, Columbia River Basin, Washington and Oregon, 2009–10.


[Station names are shown in table 3. Concentrations are in micrograms per liter; Acute: Criteria refer to the average concentration for 1 hour. Chronic: Criteria refer to the average concentration for 4 days, neither of these criteria should be exceeded more than once every 3 years. All criteria are based on concentrations in filtered water, except for mercury, which is based on concentrations in unfiltered water; a hardness of 50 milligrams per liter was used for criteria calculations; there were no exceedances of criteria in stormwater collected in Richland, Hood River, St Helens, or Longview. References for criteria are: U.S. Environmental Protection Agency (EPA), 2009b; Oregon (OR) Department of Environmental Quality, 2010b; Washington (WA) State Department of Ecology, 2003. Abbreviations: CMC, criterion maximum concentration; CCC, criterion continuous concentration. E, estimated]

First posted April 25, 2012