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Home > Programs and Policy > Habitat Conservation > Federal Lands > Border Policy

San Pedro Riparian National Conservation Area

Flowing from Mexico into the United States, the San Pedro River is renowned as one of the last undammed, free-flowing rivers in the Southwest.  The 56,431-acre San Pedro Riparian National Conservation Area (NCA) managed by the federal Bureau of Land Management (BLM) stretches 40 miles north into Arizona from the U.S.-Mexico border.

Border Wall Construction Resumes

On Nov. 1, Defenders of Wildlife and the Sierra Club filed an amended complaint in U.S. district court which challenges as unconstitutional the Bush administration’s power to single-handedly waive any and all United States laws to continue construction of border wall segments in environmentally sensitive areas.

The San Pedro River and surrounding watershed are one of the most biologically diverse areas of the U.S. This diversity stems from the San Pedro’s location at the convergence of four major ecosystems—the Sierra Madre and Rocky Mountains, and the Sonoran and Chihuahuan deserts.

The River and its larger watershed have plants and animals from all of these ecosystems. The San Pedro River and NCA harbor particularly incredible bird diversity—more than 100 species of breeding birds and an additional 250 species of migratory and wintering birds occur in the area, representing approximately half of all known avian species in North America. In addition to a diversity of birds, there are 83 species of mammals documented along the San Pedro River corridor.

Wildlife Hero:

Up Against A Fence

Bill Odle, wildlife heroBill Odle knows better than anyone about the damage a border wall along the U.S.-Mexico border will do to the breathtaking lands and unique wildlife that call this area home.

Learn more in this month's issue of Wildlife eNews.

The San Pedro is an important wildlife migration corridor linking populations in Mexico to habitat in the U.S. The San Pedro region has been designated as a World Heritage Natural Area by the United Nations World Heritage program and a Globally Important Bird Area by the National Audubon Society, American Bird Conservancy, and the international Commission for Environmental Cooperation.

Unfortunately, the National Conservation Area designation for the area has not excluded it from the impacts of illegal border traffic and enforcement activities facing the entire borderlands region.

On October 10, 2007, a federal judge granted a motion by Defenders of Wildlife and the Sierra Club to halt construction of a damaging border wall that was being built in the San Pedro Conservation Area until further study of its impacts is conducted by government agencies.

The proposed border wall road and vehicle barriers would:

  • Cross the San Pedro River and its floodplain, as well as over 60 seasonal streams and desert washes causing erosion and sedimentation into the river impacting habitat
  • Block wildlife movements that ensure healthy wildlife populations
  • Increase the likelihood that invasive species will colonize an ecosystem of international importance
  • Shift undocumented migrant traffic, enforcement activities and associated degredation into adjacent wildlands, including rugged and ecologically-sensitive Sky Island* mountain ranges


    *Sky Islands are tall mountain ranges that rise up from a "sea" of surrounding desert to support diverse ecosystems. These mountains receive enough moisture to sustain woodlands and forests, and provide niches for unique species that can only be found in these isolated "islands" of habitat.