Rangeland Salinity Degrades Impoundments and Soil Quality in Northwest South Dakota

Author: Patrick Kozak, Program of Atmospheric and Environmental Sciences

Mentor: Dr. Lisa Kunza, Program of Atmospheric and Environmental Sciences and Department of Chemistry, Biology, and Health Sciences

Mentor: Dr. Kurt Chowanski, Department of Chemistry, Biology, and Health Sciences

Mentor: Dr. Dan Heglund, Department of Chemistry, Biology, and Health Sciences

Rangeland and water quantity and quality across the western United States are influenced by soil salinity through transport and concentration. Butte and Harding counties in northwestern South Dakota have over 10,000 identified impoundments as primary water sources that may be influenced by regional soil salinity, thereby, effecting water quality associated with riparian areas used by livestock and wildlife. To evaluate the spatial variation of impoundment and soil salinity we selected 160 impoundment locations on public lands across 12 HUC12 subwatersheds. Impoundment conductivity, soil conductivity, and soil salt concentrations upgradient and downgradient were measured for each impoundment. We also derived physical data about impoundments and their drainage area (impoundment area, impoundment drainage area, percent bare ground impoundment drainage area) to assess upgradient soil salt transport and its influence on impoundments and downgradient soils. Upgradient soil conductivity and impoundment conductivity are correlated, which implies salts transported from upgradient soils to influence impoundments. Across the study area, downgradient salinity either increased or stayed the same in relation to upgradient soil salinity. A better understanding of soil salinity transport and its effects on impoundments and rangeland health will provide rangeland managers with information that may improve rangelands in the region.