Habitat Restoration on the Lower San Pedro River

4 minute read

San Pedro River Below The San José Mountains

Program: Lower San Pedro Pastureland Conversion 

Location: Lower San Pedro River Wildlife Area, Arizona


  •     Groundwater Conservation & Management 
  •     Wildlife & Habitat Protection 

The San Pedro River is the last major undammed river in the American Southwest. Called one of “America’s Last Great Places” by Life Magazine, it runs for 140 miles through the Sonoran Desert from northern Mexico to southern Arizona, where it meets the Gila River, a tributary of the Colorado. This area is home to a variety of unique wildlife including the jaguar, coatimundi, and ringtailed cat, as well as more than 300 species of birds, including the endangered Western yellow-billed cuckoo. 

In fact, the San Pedro River hosts more than 2/3 of the avian diversity in the U.S. along its banks, making it a critically important wildlife area. 

In the last few decades, rapid development and population increases in Southern Arizona have significantly increased groundwater pumping along the river, decreasing the river’s flows by as much as 40% since 1940. Large portions of the San Pedro are now going dry, negatively impacting thousands of acres of riparian forests and wildlife along the river.  

ECOS provides support to the Arizona Land and Water Trust (ALWT) and the Arizona Game and Fish Department to help restore and improve the natural hydrology and habitat along a seven-mile long stretch of the river known as the Lower San Pedro River Wildlife Area (LSPRWA). This partnership is helping convert over 100 acres of agricultural fields historically planted with corn and wheat and watered from wells to native grass pasturelands. Native grasses are adapted to the soil and their deep roots allow them to store water gathered mostly from rainfall, eliminating the need for water to be pumped from the river. The ALWT estimates at least 710 acre-feet of water will be saved in the first six years of the phased crop conversion, with as much as 610 acre-feet per year thereafter. The grasses will help capture surface water, help restore the water table, and improve overall water quality while providing protective habitat areas for wildlife, including the hundreds of nesting and migratory birds on the San Pedro’s fly path. 

We’re honored to support the work of restoring and protecting the LSPRWA, ensuring it will continue to sustain the broad array of bird and wildlife that attracts visitors from across the country.