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Rural Programs

Middle San Pedro

The Middle San Pedro watershed is a northwest-southeast trending basin in Cochise and Pima Counties in southeastern Arizona.

The watershed includes parts of two ground-water basins designated by the Arizona Department of Water Resources: the southern part of the Lower San Pedro Basin and the northern part of the Upper San Pedro Basin.

Benson is the largest city in the watershed and had a population of about 4,900 in 2005. The population of the watershed has grown moderately by a factor of about 1.5 during the past 20 years (ADWR, 2005; U.S. Census Bureau, 2006), but it is expected to rapidly increase during the next 20 years as residential developments are constructed for retirement communities or for satellite communities of nearby Tucson.

Watershed Studies

Hydrogeologic Investigation of the Middle San Pedro Watershed



[ Back to Watershed Map ]

If the approved and planned developments are constructed as scheduled, the population of Benson is expected to increase to more than 50,000 by 2025.

Groundwater is the primary source of water and is essential to support a growing population, agriculture, industry, and the riparian habitat of the San Pedro River.

The city of Benson, Cochise County, the public, and other interested parties are concerned about the future availability and sustainability of the water supply.

Increased groundwater pumping could have several undesirable consequences, such as (1) loss of available ground-water storage, (2) increased cost of pumping, (3) need for deepening existing wells, (4) need for new wells, (5) decreased quality of drinking water, (6) land subsidence, and (7) damage to the riparian habitat of the San Pedro River. To be effective and acceptable to all interested parties, planning and management of the ground-water supply needs to be guided by an objective and comprehensive scientific understanding of the ground-water system.

In 2005, the U.S. Geological Survey (USGS) began an investigation of the hydrogeology of the middle San Pedro watershed in cooperation with ADWR.  The primary objective of this project is to improve the understanding of the hydrogeology of the middle San Pedro watershed.

The project is part of the Rural Watershed Initiative (RWI), which is a program established by the State of Arizona and managed by the ADWR.

--Courtesy of the U.S. Geological Survey


External Links Outside of the ADWR Network

       Community Watershed Alliance of the Middle San Pedro Valley OffSite Icon


Hydrology Division Navigation Links

Use the above links to navigate the Hydrology Division