Examination of Dust and Air-Borne Sediment Control Demonstration Projects

Lake Tahoe's water clarity has decreased from ~100 feet in the 1970 to ~70 feet in the last few years. Fine inorganic particles are causing about 58% of light attenuation in Secchi disk measurements of water clarity. The 2010 draft of the Total Maximum Daily Load (TMDL) report indicated that the sources of sediment include urban upland loading (i.e., storm water runoff, 72%), non-urban upland loading (9%), atmospheric deposition (both dry and wet, 15%), and stream channel erosion (4%). The project report describes measurements and results collected in the Tahoe Basin that investigate the transport, deposition, chemistry, and emission control strategies of road dust that is a primary component of both the upland loading and atmospheric deposition sources.

Road side experiments were conducted at three sites around the lake. Instruments measured the composition of the aerosol emissions and how they were depleted as they passed through landscapes ranging from open fields to dense aspen and willow stands. The University of California-Davis Rotating Drum Impactor was used to measure size distributions and chemistry next to the roadway source. Data from the 2007 DRI TRAKER study (SNPLMA Round 5) were revisited to estimate the cost-effectiveness of emission control strategies (including street sweeping, summer construction, road resurfacing, road shoulder paving, anti-icing, and abrasive type) that address airborne particulate matter less than 10 microns (PM₁₀) emission control strategies including: street sweeping, summer construction, road resurfacing, road shoulder paving, anti-icing, and abrasive type.