Canyon Lake, a storage reservoir and popular recreation spot on the Salt River, will be drained for the first time in 20 years starting this month.
On Sept. 8, the Tonto National Forest closed the lake off from visitors for the next 16 weeks. The Bureau of Reclamation and Salt River Project have started to draw down the water level at the lake by 54 feet to begin safety inspections and maintenance.
”Every 20 years, SRP is required to draw the lake down essentially to see all the equipment that is submerged by water,” said Matt Pendergraft, director of hydro-generation for SRP. Lowering the water level reveals intake gates and other gear at the dams, including Horse Mesa Dam and Mormon Flat. “It gives us the opportunity to check everything to make
sure it's safe to operate,” he said.
Boat ramps, marinas and other access points will remain closed for the entirety of the project, but State Route 88, which runs along the lake’s southern shore, will stay open to the public.
Mormon Flat, which dams Canyon Lake, was constructed in 1925, and is one of SRP’s oldest dams. The last time the lake was drained was in 2007, and before that in 1987.
SRP operates four major reservoirs along the Salt River — Roosevelt, Apache, Canyon and Saguaro. Built in the early 1900s, they help provide water and energy to 2.5 million residents living in the Valley. Apache Lake is scheduled for its drawdown around 2030, according to Pendergraft. The maintenance cycle helps make sure the dams, and SRP’s water delivery system, keeps running smoothly.
With 18.6 billion gallons of water, the capacity of nearly 30,000 Olympic-size swimming pools, Canyon Lake can provide enough water for 173,000 households a year. All that water will take four weeks to draw down and another four to fill it back up.
But the water won’t be wasted. As the lake is lowered, the water will flow into Saguaro Lake and the lower Salt River before being delivered to customers in the Valley. Some will also be stored in the other SRP reservoirs nearby. The drawdown won’t affect water deliveries, SRP said.
The maintenance will take crews about eight weeks to complete.
“ I expect it will be in, what we call “full pool,” where Canyon Lake will be full, in January,” Pendergraft said.
After those 16 weeks are up, water will funnel back into the lake from upstream at Apache and Roosevelt lakes.
Sarah Henry covers environmental issues for The Arizona Republic and azcentral. Send tips or questions to sarah.henry@arizonarepublic.com.
Environmental coverage on azcentral.com and in The Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust.
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This article originally appeared on Arizona Republic: Canyon Lake closing for 16 weeks of inspections and maintenance
