Lakebed sediment and shallow ground water chemistry at the Umetco Sodium Sulfate Disposal Facility, Owens Lake, California

The effects of constituent migration from the Owens Lake Sodium Sulfate Disposal Facility on the chemistry of the nearby lakebed sediments and shallow ground water were investigated as part of a larger study of the facility. The waste consists primarily of the same sodium sulfate minerals, thenardite and mirabilite, as the naturally occurring salt crust; however, the waste contains higher ammonia and fluoride concentrations. Using probability distribution diagrams, distinct populations of constituents have been identified in shallow ground water and surface sediments at the site. Elevated ammonia and fluoride concentrations near the disposal facility are the result of several processes, including disposal of waste material on the lakebed before the impoundment was constructed, transport of waste material constituents by water impounded against the pile from an adjacent artesian well, and limited migration through the shallow subsurface ground water at the site.