Technical Abstract: Sheep concentrate on bedgrounds at night which results in disproportionate manure, and thus nutrient, deposition and soil disturbance. The study objective was to determine the immediate and long-term effects of sheep bedding on runoff and runoff-water quality. Rainfall was simulated at 3 sites in 2 years. Within each site and year, 4 off-bedground plots (0.5 m2) and 8 on-bedground plots were selected. A random half of on-bedground plots were protected from sheep disturbance (i.e., unbedded). Rainfall was simulated at 160 mm/hr for 30 min. Runoff was collected every minute for infiltration and erosion. Water samples were collected at 3 intervals for N and P analysis. Final infiltration rate for all treatments exceeded 93 mm/hr, which is high, but mean off-bedground infiltration rate was greatest at 152 mm/hr. Mean erosion rates for all treatments were less than 1.4 Mg/ha, but off-bedground (0.03 Mg/ha) and on-bedground, unbedded (0.07 Mg/ha) treatment erosion rates were significantly less. Mean total-N and total-P export for all treatments were less than 12.0 kg-N/ha and 3.8 kg-P/ha, but export from off-bedground (0.4 kg-N/ha and 0.1 kg-P/ha) and on-bedground, unbedded (0.8 kg-N/ha and 0.3 kg-P/ha) treatments were significantly less. On subalpine rangelands, only recently bedded bedgrounds will have hydrologic function that is significantly different from off-bedground areas. Considering the low risk of runoff, sediment, and nutrient yield, the small area involved in bedgrounds, and the position of bedgrounds on the landscape, it is unlikely that sheep bedding activities will cause off-site effects on stream water quality in rangeland watersheds.