PBT Trend Monitoring: Measuring Lead in Suspended Particulate Matter from Washington State Rivers and Lakes, 2011 Results

Mathieu, Callie; Friese, Michael

The Washington State Department of Ecology began a long-term study on lead in suspended particulate matter (SPM) as a component of Ecology's persistent, bioaccumulative, and toxic chemical (PBT) monitoring program in 2008. The goal of this study is to evaluate spatial and temporal trends in environmental levels of lead in Washington State waterbodies. This report summarizes results from the fourth year (2011) of the long-term study. A total of 59 SPM samples from 15 river and stream monitoring sites were analyzed for lead in the spring and fall of 2011. Concentrations ranged from below detection limits to 1,7i80 mg/kg with a median of 64 mg/kg. The Spokane River at the Idaho border had the highest lead concentrations, followed by the Spokane River Nine Mile site. Lead concentrations were also elevated at three urban streams and the Upper Columbia River site. Six out of 59 samples (10%) contained lead levels above Ecology's proposed Sediment Quality Standard (SQS) of 360 mg/kg. All samples collected from the Spokane River at the Idaho border were above this level, as well as both spring samples from the Spokane River at Nine Mile. Four new sites were added to the project plan in 2011: three small urban streams and one small rural stream. Lead concentrations measured at the urban streams ranged from 117-237 mg/kg and were higher than 70-80% of all other data collected for this program from 2008 to 2011. Mean lead levels were significantly higher at the three urbanized streams than the reference stream Huge Creek. In a qualitataive temporal analysis of lead smaples collected between 2008 and 2011, very few monitoring sites displayed consistently increasing or decreasing patterns. Yakima River data showed generally decreasing levels each year. The two mid-section sites on the Columbia River - McNary Dam and Rock Island Dam - showed lead levels generally increasing each year. At this time, the small sample size prohibits a quantitative statistical temporal analysis. [The Queets River in Olympic National Park was one of the monitoring sites.]

PBT Trend Monitoring: Measuring Lead in Suspended Particulate Matter from Washington State Rivers and Lakes, 2011 Results

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