More About the Santa Cruz River Watershed

The Santa Cruz River watershed is the land that water runs over, under, or through, on its way to the Santa Cruz River. The river begins in Arizona, flows south into Sonora, Mexico, makes a u-turn, and flows north back into Arizona and through Santa Cruz County, Pima County and the City of Tucson. The Santa Cruz River is the only river to cross the U.S./Mexico border twice (see map below, or Download a PDF copy).

The Santa Cruz River and major tributaries sustain one of the country’s largest cottonwood-willow riparian forests and provide habitat to numerous species, including the endangered Southwestern Willow Flycatcher and Gila Topminnow.

The Santa Cruz River:

* feeds agricultural and ecological processes that contribute to local economies;
* increases municipal water supplies;
* sustains invaluable riparian ecosystems in rural and urban areas;
* provides many imporant ecosystem services or benefits to local communities; and
* is central to the culture of the region.

As the primary water resource in Santa Cruz County, the Upper Santa Cruz River (USCR) provides water to communities, farmers, and ranchers. The USCR aquifer (groundwater storage system) is generally shallow with limited capacity and extreme sensitivity to drought.

Along the USCR, people and river ecosystems depend upon the same sources of water - notably surface flow in the river and shallow groundwater. Climate predictions forecast longer and more intense droughts for the region which could diminish supplies of water.  Meanwhile, growing populations increase demand for clean water. The EPA has a taskforce that focuses on water quality challenges in the U.S./Mexico border region. One of these challenges centers on the Nogales International Wastewater Treatment Plant, which discharges 15 million gallons of treated effluent (wastewater that has been cleaned to an accepted level) a day into the river in Santa Cruz County. While this discharge creates water quality concerns, the effluent also nourishes the riparian vegetation and recharges the aquifer.

Many local planning and research efforts have focused on assessing the values, threats, and needs of the USCR and associated riparian habitat.

• In 2004, Santa Cruz County approved a comprehensive land-use plan that identified the USCR as an important regional resource and specifically stated on page 11 that “the Santa Cruz River and its watershed should be conserved and managed as a ‘Living Ecosystem.’ ” Download the plan (pdf).