Aggressive coalbed natural gas (CBNG) development in the Powder River Basin (PRB) of Montana and Wyoming is driven by the Nation's growing demand for energy. Wyoming's PRB had over 13,000 CBNG producing wells in 2004 with more than 50,000 future wells projected. Extraction of CBNG is associated with production of significant volumes of saline-sodic co-produced water in the PRB, estimated to exceed 162,000 ha-m by 2020. Suitable water- management strategies will need to be developed and implemented to address long-term soils impacts from these large water volumes. Land application with sprinkler irrigation systems is a common method for managing these waters. This study examined various soil and native vegetation impacts resulting from up to 5 seasons of land application with saline (EC = 1.6 to 4.8 dS m -1 ) and sodic (SAR =17 to 56) CBNG water. Treated (irrigated) and representative control (non- irrigated) areas were established at several study sites and examined through the 2003-2005 field seasons. Soil and vegetation types, water application rates, and water and soil treatment strategies were variable across study sites so parameters from each treated area were compared directly to those from representative control areas. Soil texture, pH, EC, SAR, bulk density, surface infiltration rate and Darcy flux rates were measured at various depth intervals to 120 cm. Multiple year applications of CBNG water produced consistent trends of increased soil EC and SAR values at depths to 60 cm, reduced surface infiltration rates and reduced Darcy flux rates to 120 cm. These differences were significant (P<0.05 or P<0.10) at most depths on most sites. CBNG water applications also resulted in significant (P<0.05) increases in native perennial grass biomass production and cover (treated vs. control areas). However, species diversity as measured by evenness was reduced. Biological effects were variable and complex, reflecting site specific conditions and management strategies. These findings indicate concern for effective Na + and soluble salt leaching success with