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<br /> <br />II. SUMMARY OF IMPORTANT RESULTS AND CONCLUSIONS <br /> <br />1. Annual salt yields were measured at three locations underlain by Mancos <br />shale. Surface runoff produced an average of 0.07 metric tons (t) of <br />salt per hectare (0.03 English tons/acre, hereafter referred to as <br />tons/acre) during 1981 summer and fall convectional storms on three small <br />moderately sloped watersheds on Mancos shale in the Price River Basin. <br />t.) Approximately 0.11 t/ha/yr (0.05 tons/acre/yr) of salt are estimated to <br />W have been di scharged from three small moderately sloped watersheds on <br />~ Mancos shale at Badger Wash in western Colorado. Roughly 0.23 t/ha/yr <br />CO (0.10 tons/acre/yr) of salt and 7.75t/ha/yr (3.4 tons/acre/ yr) of <br />sediment accumulated in a series of small catch basins over a seven-year <br />period on steep Mancos shale badlands near Huntington, Utah. <br /> <br />2. Storm-period salt concentrations are closely related to suspended <br />sediment concentrations except at the onset of runoff. We hypothesize <br />that flushing of concentrated in-channel salts causes a comparatively <br />high ratio of total dissolved solids (TDS) concentration to total solids <br />(TS) concentrations at the onset of runoff. <br /> <br />3. Highest salt and sediment concentrations in three small washes in the <br />Price River Basin, Utah, occurred in the first streamflow event following <br />a long period where no discharge occurred, suggesting sediments and salts <br />became available for transport during that period. <br /> <br />4. Three broad geomorphic units and 11 different soil series in 22 mapping <br />units were recognized and described at the Woodside, Utah salinity study <br />site. Eleven plant communities were recognized and described within the <br />study area. Soil moisture and soil soluble salts appear to be primary <br />factors affecting vegetation distribution and community differences. <br /> <br />5. Salt and sediment yields from steep Mancos shale badland formations are <br />much higher on a per unit area basis than from gently sloped Mancos shale <br />lowlands. Rilling accounts for approximately 80% of the erosion on steep <br />Mancos shale badlands. Interri11 erosion accounts for almost all upland <br />erosion on gently sloped Mancos shale lowlands. <br /> <br />6. Li vestock trampli ng on dry, fi ne, gray, crusted soil s on Mancos sha1 e <br />lowlands causes surface crusts to be broken and a temporary increase in <br />soil erodibility. These effects are offset by increased depression stor- <br />age and higher total infiltration. Higher concentrations of salt and <br />sediment occurred from trampled study plots. However, reduced runoff <br />creates the potential for livestock trampling to reduce total sediment <br />and salt yields from this soil-landform type. We do not expect this <br />conclusion to apply to compactab1e soils where trampling, especially <br />under moi st soil condi ti ons, may decrease i nfi ltrati on and increase <br />runoff and surface erosion. <br /> <br />7. Basef10ws from ground water sources and irrigation return flows in the <br />Price River Basin, Utah, contribute over three times the annual salt load <br />in the Price River at Woodside, Utah, than surface runoff from short- <br />duration summer convectional storms. <br /> <br />2 <br />