SRP pulls back curtain on Mormon Flat Dam maintenance work at Canyon Lake

Salt River Project recently offered a glimpse of its maintenance work at Mormon Flat Dam near Apache Junction in the Tonto National Forest.

Canyon Lake, just behind the dam, has been closed since Labor Day so SRP can draw it down 54 feet, diverting the water to Saguaro Lake.

SRP drains Canyon Lake by about 65% every 20 years or so for upkeep of Mormon Flat Dam.

This is the time of year when SRP switches from the Salt River to the Verde River to meet customer demand, making the drawdown possible.

“We are doing our 20-year drawdown so we can do gate maintenance and we can do intake maintenance on equipment that’s submerged underwater,” Matt Pendergraft, SRP’s director of hydro generation, told KTAR News 92.3 FM on Oct. 14.

SRP relies on reservoirs and dams along the Salt and Verde rivers to deliver water to about 2.5 million Phoenix-area residents. The utility company also provides electricity, some generated by hydroelectric dams, to more than 1 million customers in central Arizona.

The U.S. Bureau of Reclamation owns the dams, while SRP operates and maintains them.

How does SRP keep Mormon Flat Dam in working order

With the Mormon Flat Dam gates now exposed, SRP can lift both 400,000-pound metal doors to ensure they work, a three-hour process for each gate.

“These gates are what keep the dam safe because they open up and pass water through, up to 150,000 cubic feet per second. So, it’s very critical that this equipment works perfectly,” Pendergraft said.

Crews will also wash and paint the gates to protect them from corrosion.

“We’ll sandblast everything off and we’ll recoat it with a protective sealant, and it will keep it nice and good for the next 20 years,” Pendergraft said.

SRP is also removing the intake hydraulics and sending them to a shop in Apache Junction to be refurbished.

The whole process takes about 16 weeks: four weeks for the drawdown, eight weeks for the maintenance and four weeks to fill the lake back up.

As a result, Canyon Lake will remain closed until mid-January.

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