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Know the West

D-Day for dam decommissioning approaches

  Preparations have begun to bring down the dam that has withheld water from 14 miles of Fossil Creek in central Arizona for almost a hundred years.

In 1908, laborers built Arizona’s first commercial hydroelectric plant, which diverted more than 95 percent of Fossil Creek’s water. The plant, along with a second facility built nearby in 1914, generated power for parts of Phoenix and for mining communities near Prescott and Jerome.

But these days, the two plants, which together generate four megawatts, power only about 1,000 homes. So, in 1999, Arizona Public Service — the state’s biggest electric utility and owner of the plants — bowed to public pressure to restore Fossil Creek, and agreed to shut the plants down. The utility also promised to put $13 million toward resuming full water flow and re-establishing native fish populations (HCN, 12/6/99: Fossil Creek Will Flow Again).

In fall 2004, the Federal Energy Regulatory Commission finally approved the plan. In November, 90 interagency biologists airlifted about 1,200 native Arizona fish, including speckled dace and roundtail chubs, to safety in holding tanks. Then they poisoned the non-native fish, and later returned the natives to the creek’s upper reaches.

The utility plans to redirect the reservoir’s water around the dam for a couple of years, then lower the 25-foot-high main dam by 14 feet. "We want to re-establish habitats before bringing it down," says Mark Fallon, an Arizona Public Service spokesman.

Full flows and plant decommissioning were originally scheduled for December 2004. Heavy rains and pending final approval from the Federal Energy Regulatory Commission pushed that date back to mid-May. The entire area should be restored to its pre-power plant state by 2009. Says Fallon, "That’s when we’re scheduled to walk out of the forest."