In New Mexico, under the pressures of climate change and population growth, demand for water is increasing, and there is mounting evidence that the available water supply may actually be decreasing. While water use conservation efforts are necessary, there is great interest in finding ways to increase the available water supply. Tree thinning in mountain regions is an effective way to decrease fire danger in areas where forests are overgrown. Potentially, tree thinning can also be used as a tool to increase water supply. This report describes a watershed study in the southern Sacramento Mountains, which focused on the effects of tree thinning on the hydrologic system, specifically on the potential to increase groundwater and surface water availability in the Sacramento Mountains.