THE SAN PEDRO RIVER

The San Pedro River watershed is one of the most biologically diverse ecosystems on Earth, with the highest diversity of vertebrate species in the inland United States. Located along the interface of the Sonoran and Chihuahuan deserts and influenced by both the Rocky Mountains and the Sierra Madre, it’s one of North America's most important wildlife havens, with more than 400 bird species — nearly half the U.S. total — living in or migrating through the basin. It’s also home to 180 species of butterflies, 87 species of mammals, and 68 reptiles and amphibians.

Several San Pedro-dependent species are already imperiled. The jaguar, Mexican spotted owl, cactus ferruginous pygmy owl, southwestern willow flycatcher, yellow-billed cuckoo, loach minnow, spikedace, and Huachuca water umbel are the most threatened of the myriad species that need the river’s perennial flow and riparian canopy for survival.

In recognition of its biological importance, the American Bird Conservancy picked the San Pedro as its first "Globally Important Bird
Area," and The Nature Conservancy deemed it one of the "Last Great Places" in the western hemisphere. In 1988, Congress recognized its value by establishing the nation's first Riparian National Conservation Area along a 45-mile stretch of the upper San Pedro. If this biodiversity oasis is to endure, it will be because humans display the foresight to preserve the last free-flowing river of the desert Southwest.

But the San Pedro River is drying up. Unsustainable pumping of the groundwater that supports the river has caused base flows to decline by 67 percent since the 1940s. The current population of more than 50,000 people in the upper basin is pumping thousands of acre feet (billions of gallons) more out of the aquifer each year than are recharged by rainwater. By 2020, the deficit is projected to reach 13,000 acre feet (4.2 billion gallons) annually. The burgeoning water deficit is caused by unsustainable population growth and a lack of effective water-conservation planning.

The population of the town of Sierra Vista has exploded in recent years, driven largely by nearby Fort Huachuca, the U.S. Army base that is the largest single water user in the valley. While it has made great strides in reducing per-capita water use on post, the fort is also the region's biggest employer, driving growth and excessive, uncontrolled pumping off the post. Sierra Vista, Cochise County, the state of Arizona, and the federal government have not shown the political will to protect the river. Unless things change soon, the San Pedro will resemble the lower reaches of the Santa Cruz, Gila, Salt, and other Arizona rivers: dry, treeless, and devoid of the diversity of life that once graced its waters and shores.

In June 2008, we sued Pinal County for misusing the San Pedro by creating an unrestricted passageway across the river, straight through the San Pedro river conservation area southeast of Phoenix. Our lawsuit seeks to revoke the county’s illegal seizure of the land on which the passageway was created, so that dredge-and-fill operations cease and off-road vehicles drawn to the passageway don’t destroy important habitat.

OUR CAMPAIGN

The Center has worked to protect the San Pedro and its wildlife since filing our first Endangered Species Act petition to protect the Mexican spotted owl in 1989. The Center has also won Endangered Species Act protection for the cactus ferruginous pygmy owl, southwestern willow flycatcher, jaguar, Sonoran tiger salamander, and Huachuca water umbel, and is seeking federal protection for the yellow-billed cuckoo, Gila chub, and Chiricahua leopard frog. The Center has won the designation and protection of specific critical habitat areas along the river for the willow flycatcher, pygmy owl, loach minnow, and spikedace, and in the upper watershed for the spotted owl.

The Center is currently working on several fronts to protect the San Pedro, including pressuring Fort Huachuca to adequately mitigate its presence both on and off the base and challenging the hydrologic basis of Arizona water law. A key step forward for 2008 would be the repeal of a rider to the 2003 Defense Authorization Bill that exempts Fort Huachuca from responsibility for the impacts of growth and pumping off the post.

In the spring 2007 session, the Arizona state legislature authorized the creation of a special water district for the Sierra Vista subwatershed. Although local political realities may preclude much progress on this front, the Center will be pushing for the strongest regulation possible. Ultimately, if the San Pedro is to be saved, it will be necessary to change the way Arizona water law treats groundwater pumping near riparian areas. Along those lines, the Center is exploring the potential for a statewide ballot measure that would protect rivers like the San Pedro from depletion through excessive groundwater pumping.