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for people who care about the West

Water connections


Thank you for investigating threats to the San Pedro River east of Tucson, Arizona (“Federal agency retracts opposition to Arizona project,” HCN, 1/22/18). The river is unique in that it is one of the last free-flowing desert streams in the United States, supporting riparian habitats for aquatic and terrestrial species of conservation interest. In the San Pedro Valley, groundwater and surface water are connected. Thus, wells may pump groundwater that would otherwise flow to the river and also eventually pull water out of the river towards well fields, resulting in reduced streamflow or drying the river. How to manage groundwater and surface water as a linked resource remains an important policy question being played out across the Western U.S. today. For example, Sarah Tory’s recent hcn.org article on the Texas-New Mexico Supreme Court case highlights the interstate dispute over how groundwater pumping may have reduced Rio Grande flows (“A Southwest water dispute reaches the Supreme Court,” hcne.ws/groundwater-fight). In addition, California’s 2014 Sustainable Groundwater Management Act includes a unique provision that groundwater be pumped at rates that avoid undesirable results, which include “depletions of interconnected surface water that have significant and unreasonable adverse impacts on beneficial uses of the surface water.” It will be interesting to see how these legal and policy actions translate to practical water resource management strategies. 

Brad Wolaver
Austin, Texas