Technical Abstract: The USDA-ARS Jornada Experimental Range (JER)(738 km2) north of Las Cruces, NM, was established in 1912 to assess the impact of grazing in an arid land environment. The majority of rainfall occurs during June-September with an annual mean of 241 mm. Ecophysiological studies employing stable isotopes are underway to identify the sources of water uptake for shrubs and grasses and how the temporal and spatial variability affects the amount and sources of water used by various species. Infiltrometer and rainfall simulation studies are being used to quantify the role of soil biota in controlling soil surface hydrology in arid and semiarid environments and to define the resistance and resilience of different soils and plant communities to different disturbance regimes. Previous work at the Jornada quantified the interception of rainfall for different shrubs and infiltration rates in root-plowed areas. Runoff was measured with a 2.8 m3/s critical depth flume on a shrub-dominated, 7.4-ha watershed from 1977-1986. These flow measurements were reactivated in 2003. Runoff and sediment measurements were also made on plots, microwatersheds, and stock ponds. Because of the aridity of the Jornada, there have been numerous rangeland rehabilitation treatments with the goal of slowing or reversing the shrub encroachment into grasslands. The most effective treatments have revolved around redistribution of surface runoff and its effects on infiltration and soil moisture. Simple, low profile, water-ponding dikes seem to have had the best success in achieving a positive vegetation response.