James Leenhouts, Ph.D.

The Southwest Region includes ten science centers conducting work for all five USGS mission areas, about 1300 employees, and an overall annual budget of around $280 million. The Region brings multidisciplinary USGS science to address cross-cutting challenges across the southwest, including California’s Bay Delta and the Colorado River.

Jim joined the USGS Arizona Water Science Center in 2000. Between 2000 and 2007, Jim worked on a project in the Upper San Pedro Basin to quantify the groundwater and surface-water requirements of the riparian vegetation and later on the congressionally requested “Section 321” project to assess progress toward a sustainable groundwater yield in the basin. Jim also assisted the Pinal Creek Toxics project with sampling and analysis of manganese contamination in the Globe-Miami area of Arizona.   

Jim's graduate work focused first on the development of techniques to use isotopic ratios of boron as a co-migrating tracer to track and identify sources of nitrate contamination in groundwater.  Dissertation work examined soil-water/plant interactions with an objective to develop techniques for using plants as 'samplers' of geochemical signatures in soil and groundwater.  Jim's work at USGS focused on stream-aquifer-plant interactions in the San Pedro River basin and later evolved to working with water resource managers and stakeholders in the group to understand the relations between groundwater withdrawals and depletion of streamflow.