June 22, 2001 – The U.S. Bureau of Land Management set aside nearly 480,000 acres of wildlife habitat in the Sonoran and Mojave deserts as off-limits to off-road vehicle use. The protections were part of a settlement of the Center's larger California Desert Conservation Area lawsuit.
April 12, 2002 – A federal court sided with the Center when it ruled that a planned expansion of Fort Huachuca was dewatering the San Pedro River, jeopardizing the existence of several endangered species in the process.
June 9, 2003 – After two years of steady local pressure conjured by the Center, the Bureau of Land Management ordered Grupo Mexico/ASARCO to remove an illegal pipeline, powerline, and road that crossed the Ironwood Forest National Monument near the Silverbell mine.
November 7, 2003 – Despite opposition from the Center and allies, Congress passed the Renzi rider, attached to the Defense Authorization Act, that exempted military gardens, lawns, pools, and golf courses from environmental laws — and exempted Arizona's Fort Huachuca from responsibility for groundwater pumping. The rider remains the single largest impediment to the Center's legal work to protect the upper San Pedro River from the overpumping of groundwater.
2004 – The Center developed the Sonoran Desert Conservation Plan, an award-winning, comprehensive report on best management practices for continued growth in Pima County while protecting irreplaceable natural resources.
June 8, 2004 – The Center, along with other environmental groups and private citizens, filed a notice of appeal against the Arizona Department of Water Resources and the state of Arizona over their misrepresentations of the size of the water supply in the Sierra Vista sub-basin — which encouraged development that would destroy irreplaceable San Pedro habitat.
December 4, 2004 – The Center filed a notice of intent to sue the city of Prescott over a plan to purchase the JWK Ranch for the purpose of transferring water from the Big Chino basin into the Prescott area. The project, known as the Big Chino Water Ranch Pipeline, would inevitably result in less water for the Verde River, downstream residents, and river-dependent wildlife.
April 5, 2005 – The Center, represented by Earthjustice, filed a lawsuit against the Veterans Administration, the Federal Housing Administration, and the Small Business Administration for failing to examine the environmental impact of developments relying on water from the San Pedro.
June 1, 2005 – Along with the Maricopa Audubon Society, the Center filed a lawsuit against Fort Huachuca, the U.S. Department of Defense, and the U.S. Fish and Wildlife Service for approving rapid expansions of Fort Huachuca that exceeded what was recommended as sustainable in a 2002 federal “biological opinion.” The expansions violated the Endangered Species Act and threatened species dependent upon the San Pedro River.
July 9, 2005 – For the first time in recorded history, the San Pedro River ran dry at the Charleston gage near Fort Huachuca.
March 1, 2006 – In a successful resolution to the Center's June 2005 lawsuit, Fort Huachuca announced that it would reinitiate consultation with the Fish and Wildlife Service in an effort to fulfill its obligations to protect the San Pedro River and its dependant species.
May 17, 2006 – The Center condemned a Senate vote that approved the construction of a massive triple wall over 270 miles of the U.S.-Mexico border; in addition to being ineffective in curbing illegal immigration, the wall would further damage sensitive wildlife habitat and block known migration corridors.
August 15, 2006 – The Center announced the start of a long-term campaign to protect the Verde River from a multitude of threats, including the proposed Big Chino Water Ranch Pipeline proposed by the city of Prescott.
March 4, 2008 – The Center filed a formal Clean Water Act violation against Pinal County for its ongoing destruction of rare habitat along the lower San Pedro River.
April 25, 2008 – Bureau of Land Management documents revealed that the U.S. Department of Homeland Security had ignored warnings of damage to the San Pedro River prior to exempting the border wall across the San Pedro Riparian National Conservation Area from all environmental laws.
May 14, 2008 – The Bureau of Land Management moved to protect the Sonoran Desert National Monument from off-road vehicle abuse by closing 89 miles of routes; unfortunately, the protections cover only a small portion of the monument.
June 4, 2008 – Along with the Maricopa Audubon Society and the Tucson Audubon Society, the Center filed a lawsuit against Pinal County to stop ongoing ecological damage to the Bureau of Land Management's lower San Pedro River conservation area after the agency began illegally dredging and filling in the river.
December 12, 2008 – The Center, the Sierra Club-Grand Canyon Chapter, and private citizens, represented by the Arizona Center for Law in the Public Interest, filed an administrative appeal that challenged a November 2008 decision by the Arizona Department of Water Resources allowing more than 8,000 acre-feet of water per year of water to be pumped from the Big Chino sub-basin. The proposed pumping would eventually reduce the base flow of the upper Verde River, destroying the first 25 miles of the river's habitat and eliminating river-dependent wildlife in the process.
April 22, 2009 – The Center sued the city of Prescott in Yavapai County for its failure to provide documents relating to the construction of the Big Chino water pipeline that would, ultimately, deplete the Verde River.
June 17, 2009 – The Center filed an administrative appeal that challenged the Forest Service for its failure to protect endangered wildlife and water quality in the federally designated “wild and scenic” Fossil Creek watershed when it authorized livestock grazing on 42,000 acres southeast of Camp Verde.
February 10, 2010 – The Center's June 2008 lawsuit against Pinal County was settled when the Army Corps of Engineers cited the county for its illegal activities and the Bureau of Land Management agreed to cease dredging and filling activities that were damaging the San Pedro watershed.
May 2012 –The BLM abandoned a proposal to ban target shooting in the Sonoran Desert National Monumentunder political pressure from gun advocates. Earlier plans for the monument admitted that target shooting was harming the resources the monument was established to protect.