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River dropping but for how long?
Feds order spillway closed for maxed-out Don Pedro with heavy snowpack waiting
Ceres Regional Park Flood Feb18 2017-3
The lower terrace of the Ceres River Bluff Regional Park north of Hatch Road remains closed off due to flooding from the Tuolumne River which has widened from excessive rainfall this season. - photo by Courtesy of Ryan Guy

Local government officials are worried that the federal government's order to close the spillway at Don Pedro Reservoir could spell disaster if there more heavy rains fall; or if the weather warms up quickly and melts a snowpack that is 200 percent of normal.

Turlock Irrigation District, the agency that operates the storage facility with Modesto Irrigation District, petitioned against the action but lost on Friday. Ceres Mayor Chris Vierra also wrote a letter on behalf of supporting TID's request. On Feb. 20 TID had opened one of three spillways at the dam to release 18,000 cubic feet per second to drop the level of the topped-out lake so there will be more storage space when the snow melts this spring. To reduce flooding, the releases dropped to 16,000 CFS. On Monday morning the spillway was closed in compliance with U.S. Army Corps of Engineers Flood Control Manual regarding operation of the reservoir.

As of Monday Don Pedro was at 828.58 feet. The reservoir's physical capacity is 830 feet. TID wanted to bring the reservoir down to 815 feet.

"Without adequate room in the reservoir, TID could be forced to use its controlled spillway again sometime this year," said TID spokesman Herb Smart. "Snow sensors are recording a historic snowpack with potentially millions of acre-feet of additional inflow into Don Pedro when significantly warm storms or warm weather unfold in the coming months."

TID is continuing to release water through its power generation facility at a rate of approximately 10,200 cubic feet per second (CFS) and are expected to continue at this rate to keep the Tuolumne River at the Ninth Street Bridge in Modesto below the 55 feet elevation mark.

The spillway's closure meant a decline of river level elevation in Ceres/Modesto around 3:30 a.m. Tuesday.

At Monday's Ceres City Council meeting, City Manager Toby Wells expressed concern.

"Right now they're releasing 16,000 cubic feet per second and 14,500 is coming into the reservoir so they're not making that much ground," Wells informed the council. "The snowpack above the reservoir is at 200 percent. In essence what the Army Corps said was the downstream conditions where the Tuolumne meets the San Joaquin River are more concerning than releases from the reservoir - at this point in time. So what that means is the reservoir will stay near capacity, in essence at 99 percent full, with a very heavy snowpack above it and everyone will be very cautiously watching the forecast."

The lower terrace of Ceres River Bluff Regional Park remains closed because of flooding as well as the bottom nine at the neighboring River Oaks Gof Course.

"With the snowpack we're looking at runoff conditions being very high for at least into July. A lot of water coming down the river and out to the ocean which is very unfortunate."