Weather

Update: TID reduces flow from Don Pedro spillway; area rivers running faster

Update, 11:25 a.m.: Turlock Irrigation District reports that the total outflow to the Tuolumne River of about 16,000 cfs is coming from one spillway gate plus water being released from the Don Pedro Power Plant.

At 11 a.m. Tuesday, TID began reinspecting all areas not impacted by flooding for potential restoration of power that has been turned off. “TID will continue to monitor and re-evaluate power restoration time lines based on current and forecasted river levels,” it announced. “More information on these scheduled outages is available at tid.org/riveroutage.

Update, 10:57 a.m.: Here’s a look around the county about four hours from when the spillway water is expected to hit Modesto. Area farmer Jake Wenger also caught some great video from yesterday.

Update, 10 a.m.:

The impact outlook from the spillway release at Don Pedro Reservoir was brighter Tuesday than it was the day before. Turlock Irrigation District decided Monday night to reduce the flow from the floodgate to 16,000 cubic feet per second from the initial 18,000 cfs. The reduction began at 10 p.m., TID spokesman Calvin Curtin said Tuesday morning.

The decision to reduce flow was made because “the storm basically went around the upper watershed and did not impact Don Pedro as much as anticipated,” he said. The National Weather Service has good forecast models, but predictions are just predictions, he said.

TID, which manages dam operations at Don Pedro, said Monday that the spillway would be open a minimum of four days and releases could be as high as 30,000 cfs. That remains true, Curtin said. Asked if the highest releases still could reach 30,000 cfs, he said, “It’s all based on inflow projections for the reservoir, which includes weather and runoff from the snowpack.”

For now, at least, TID is glad it was able to reduce the flow, he said. “For folks still impacted, it will help some but not all.”

A National Weather Service flood warning remains in effect through Thursday as water comes down the Tuolumne River from Don Pedro to keep the reservoir below capacity.

The water takes 23 hours to travel from the dam to Ninth Street in Modesto, so the swell should arrive about 2 p.m. The Stanislaus County Office of Emergency Services reported that the water arrived in the Waterford area about 3 a.m.

According to the weather service’s Advanced Hydrologic Prediction Service, the Tuolumne – with a flood stage of 55 feet in Modesto – was at 56.34 feet at 8:30 a.m. and flowing at 12,300 cfs.

The latest forecast data, which run through Sunday afternoon, show it peaking at 59.5 feet Tuesday at 5 p.m., flowing at 16,800 cfs. It should begin to recede slightly at 2 a.m. Wednesday, the service says. The prediction depends, of course, on what TID decides to do at the spillway.

Dry Creek in Modesto was at 79.01 feet at 9 a.m., flowing at 2,780 cfs. The hydrologic prediction service’s latest data show it getting no higher.

The California Nevada River Forecast Center showed the San Joaquin River in Patterson at 51.0 feet and 23,657 cfs Tuesday morning. Flood stage is 54.7 feet and danger stage is 55.7 feet. The maximum numbers in the forecast are 51.3 feet and 24,421 cfs.

For the San Joaquin as it flows through Newman, the forecast center showed it at 65.7 feet and 21,127 cfs Tuesday morning. Flood stage is 69.4 feet and danger stage is 70.4 feet. The forecast shows the flow getting slightly higher but the river not rising.

In other storm news, Stanislaus County appears to have been spared the strong winds with gusts up to 60 mph that had been forecast for Monday night.

Modesto Fire, Stanislaus Consolidated and other agencies reported a quiet night in terms of storm-related calls. So did the Tuolumne County Sheriff’s Office.

As for rain, downtown Modesto got 1.23 inches Monday, according to Modesto Irrigation District measurements. The heaviest was morning into early afternoon, and the most recent recorded was before 10 p.m.

The total for the season – which runs July 1 through June 30 – now stands at 15.28 inches. The 11 highest since MID began keeping records in 1889 are: 1983, 26.01 inches; 1998, 24.60 inches; 1958, 23.04 inches; 1907, 20.55 inches; 1978, 20.19 inches; 1995, 20.18 inches; 1890, 19.09 inches; 1914, 18.58 inches; 1993, 18.45 inches; and 1969 and 1925, both at 18.33 inches.

But keep in mind that four full months plus the rest of February remain in the current season.

Though the sun was out early Tuesday, the National Weather Service says the day holds a 70 percent chance of rain, and possibly thunderstorms after 10 a.m. Without thunderstorms, up to a quarter inch of rain could fall.

Tuesday night, the chance of rain decreases to 40 percent, and less than a 10th of an inch is anticipated.

Wednesday through Friday night, the forecast is for mostly sunny days and mostly clear nights.

A chance of showers returns Saturday, the weather service says, and showers are likely Sunday.

We’ll have more throughout the day on the effects of the spillway release.

To register for flood alerts on electronic devices, visit stanaware.com.

Deke Farrow: 209-578-2327

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