Establishment of Native Vegetation for Dust Mitigation On Owens (Dry) Lake.

Owens Lake (280 km²) became essentially dry by 1921, due largely to diversion of water from the Owens River for local irrigation and remote urban use.  Drying of the lakebed has resulted in extensive wind erosion making the playa one of the largest PM10 sources in the western hemisphere.  The dust creates severe air pollution and human health hazards.  One proposed mitigation strategy involves establishment of native vegetation to stabilize and trap fugitive sand.  This study investigated soil and groundwater chemistry and the distribution of native plant species in relation to salts and toxic ions in the soil and groundwater.  Parent materials for soils on the dry lakebed include fine-grained lucustrine deposits and coarse-textured eolian sands and beach deposits.  Parts of the lakebed have efflorescent salt crusts comprised largely of sodium with chloride and carbonates.  Shallow, anoxic groundwater was found to be a major limitation to the establishment of native vegetation.  Groundwater chemistry was characterized by high pH (9.3 – 10), electrical conductivity (3 – 160 dS/m), boron (up to 300 mg/L), and sodium adsorption ratio (46 – 1300), and low redox potential (Eh ~ -240 mV).  The shallow anoxic groundwater restricted the rooting zone of native vegetation.  No vegetation was found when groundwater was within 70 cm of the soil surface while an oxidized rooting zone greater than ~1.5 m was required for adequate vegetation density to stabilize saltating sand.  Raised microsites established using sand fences or groundwater drainage to lower the water table have been successful in establishing an adequate rooting zone for vegetation establishment.