Floating brine crusts, reduction of evaporation and possible replacement of fresh water to control dust from Owens Lake bed, California

SummaryOwens Lake, California, a saline terminal lake desiccated after diversion of its water source, was formerly the single largest anthropogenic source of fugitive dust in North America. Over 100 billion m−3 yr−1 of fresh water are projected to be used for mandated dust control in over 100 km2 of constructed basins required to be wetted to curtail emissions. An extensive evaporite deposit is located at the lake’s topographic low and adjacent to the dust control basins. Because this deposit is non-dust-emissive, it was investigated as a potential replacement for the fresh water used in dust control. The deposit consists of precipitated layers of sodium carbonate and sulfate bathed by, and covered with brine dominated by sodium chloride perennially covered with floating salt crust. Evaporation (E) rates through this crust were measured using a static chamber during the period of highest evaporative demand, late June and early July, 2009. Annualized total E from these measurements was significantly below average annual precipitation, thus ensuring that such salt deposits naturally remain wet throughout the year, despite the arid climate. Because it remains wetted, the evaporite deposit may therefore have the potential to replace fresh water to achieve dust control at near zero water use.