PHOENIX — A Northern Arizona University research team is studying the effects of returning water to areas with decommissioned dams, as momentum grows behind a movement to tear dams down and repair damage to waterways.
The team's work includes research on the effects of restoring water to 14 miles of riverbed in a Northern Arizona creek after a nearby dam was retired.
Fossil Creek, located in Strawberry north of Payson, presents a rich learning environment for the team.
"We're going to learn so many things about how rivers function," said Jane Marks, who leads the NAU team. "You learn a lot about a system just by changing it."
The 17-mile tributary flows down the face of the Mogollon Rim in a rugged canyon that stretches just outside Camp Verde. Water from its springs distributes minerals that build stunning layers of travertine, which create shimmering blue-green pools and waterfalls.
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The creek's reliable flow and location upstream from mining operations and growing towns proved irresistible to dam builders.
In 1909, the creek was diverted to generate electricity in the Irving power plant, and later, the Childs power plant.
Except for storm runoff, the creek was left dry.
The two plants were still producing about 4 megawatts of power in 1999 when Arizona Public Service decided to voluntarily shut down operations on the creek and decommission the dam.
Since water returned to Fossil Creek in 2005, its native fish population has increased tenfold.
State and federal wildlife agencies helped remove non-native fish from a stretch of the restored Fossil Creek and restocked it with native species, including the roundtail chub, the speckled dace and the Sonoran sucker.
Researchers are studying other aspects of the dam decommissioning, including what will happen to the tons of sediment trapped behind the structure once it's physically removed. Currently, the dam is still there, but its open gates allow the creek to flow through.
Work is also under way to prepare for an expected increase in human activity along the creek, which drew only the hardiest of hikers and campers before water was restored.
Since publishing an article on dam removal in Scientific American magazine this year, Marks has heard from a growing number of people and organizations interested in learning about the process.
She expects her work and that of her colleagues to yield valuable guidance for future projects.
"We're lucky to be able to observe it as it changes," she said. "We'll see more changes in this river in a decade than we'd see in a career on most rivers."
Studies show that nearly 500 dams have been decommissioned around the United States since the early 1980s.
The Fossil Springs dam was the first major structure in Arizona to be retired.
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