Breaking: TID preparing to open Don Pedro Reservoir spillway as early as 3 p.m. Monday

The Modesto Bee ^ | February 20, 2017 | Brian Clark

[keat]

The spillway gates at Don Pedro Reservoir could open as early as 3 p.m. Monday, but no earlier, authorities said.

The Turlock Irrigation District made the declaration late Sunday night due to “volatile changes in forecasts for upcoming storms,” an agency press release stated.

“Landowners, growers and those living along the Tuolumne River, out of an abundance of caution, should undertake necessary steps to protect their property and livestock as Tuolumne River levels will rise quickly,” the agency stated in an 11 p.m. press statement.

Opening the spillway would provide relief for the brimming reservoir, which was just under 4.5 feet from reaching its maximum as of 4:40 a.m. Monday.

A storm that’s made its way into the Central Valley and could bring up to five inches of rain in and above the Sierra foothills would likely bring the reservoir that’s about a 50-minute drive from Modesto to its maximum.

Since midnight, downtown Modesto has received 0.25 inches of rain.

The water from the spillway would flow into the Tuolumne, which runs through the eastern part of Stanislaus County, into Modesto and then to the west part of the county. It eventually runs into the San Joaquin River between Highway 132 and Grayson just east of Interstate 5.

Some residents in Modesto and west of town along the Tuolumne already have been evacuating from their homes as the river has been within inches of the 55-foot flood stage.

[Hieronymus]

Thanks for the tip. The wiki article on him made for an interesting read. I think I’ve met one of his descendants.

[Lisbon1940]

The article doesn’t say the dam/reservoir was named for the Frenchman but the location of his mining claim.

[Eric in the Ozarks]

Reminds me of the story of Rojo Rodriguez...

[keat]

Three is a dam, it had no gates but it does have a release mechanism through the power plant.

There is a spillway, it has gates. Three large gates as opposed to eight smaller ones at Oroville.

As for opening the gates, the force must be balanced by opening them simultaneously. Whether a little or a lot.

There is also an emegency weir, like Oroville, that can release water over the top.

[drellberg]

I know this is off-topic, but what is the Monday mid-day state of the Lake Oroville dam? I have hung on every word written by those in the know at Free Republic, but very little is being written the past day or two even as the storm bears down.

Would anyone favor me with an update? Thank you.

[stormer]

California has an interesting and complex history.

[AppyPappy]

The last thing I saw was that the lake level was still down.

[Terry Mross]

I thought names ending in ian were Armenian.

[keat]

It's just a screenshot so bear with me. And this was taken when the lake was lower. You can see the dam. To the left, a channel and the spillway gates. The channel is dry in this photo.

There is no concrete spillway like Oroville, just dirt and rock. The Don Pedro spillway was constructed a distance from the dam and at a 90 degree angle away. For this reason, erision of the dam is not likely.

The released water will wash out the road below and follow a natural ravine down to the river. This ravine was scrubbed to bedrock back in 1997 when the gates were first opened and little in the way of soil or vegetation exists.

Here's the area below the spillway after the 97 release.

[keat]

Oroville is down about 50 feet and still releasing more than is coming in. But rain is falling hard in the mountains. Rain, not snow. The next 24 hours will tell.

[PLMerite]

“...a French settler in California during the Mexican era.”

per Wiki: https://en.wikipedia.org/wiki/Pierre_Sainsevain

[editor-surveyor]

.
They should have been releasing long before this!

Very poor management. Don Pedro has in the past flowed over roads and spilled into McClure several times.

Don Pedro is actually owned by the University of Kalifornia.
.

[editor-surveyor]

.
What other reservoir has a Spanish name?

Certainly none in the area.
.

[keat]

New Melones is nearby, and Modesto Reservoir, if that counts.

[GreenLanternCorps]

This does:

https://en.wikipedia.org/wiki/New_Don_Pedro_Dam

[Axenolith]

Ohhhh... there’s gonna be shiny stuff in there!!!

[editor-surveyor]

.
Melones is named after the town that it inundated, not an individual.
.

[pelican001]

“Haven’t heard the name Modesto, since Gary Condit”

Modesto is also the home of “The King”, Kenny Roberts. The following is from Wiki -

Kenneth Leroy Roberts (born December 31, 1951 in Modesto, California) is an American former professional motorcycle racer and racing team owner. In 1978, he became the first American to win a Grand Prix motorcycle racing world championship.[1][2] He was also a two-time winner of the A.M.A. Grand National Championship...His dirt track-based riding style changed the way Grand Prix motorcycles were ridden.

[deport]

Here’s a few name reservoirs in CA.

https://en.wikipedia.org/wiki/List_of_dams_and_reservoirs_in_California

https://en.wikipedia.org/wiki/List_of_largest_reservoirs_of_California

[Mariner]

The reason the Tuolumne is at flood stage now is because they have been releasing all the can via the power station:

“Rising 585 feet (178 m) above its foundations and 560 feet (170 m) above the Tuolumne River,[21] New Don Pedro is a massive earth and rock fill structure containing 16,750,000 cubic yards (12,810,000 m3) of material.[2] The 1,900-foot (580 m) long dam is 40 feet (12 m) wide at the crest and over 2,800 feet (850 m) wide at the base.[1] High water releases are controlled by four sets of gates. A set of internal gates in the diversion tunnel can release up to 7,370 cubic feet per second (209 m3/s), while a hollow jet valve at the base of the dam can discharge 3,100 cubic feet per second (88 m3/s). The service spillway, controlled by three 45-by-30-foot (13.7 m × 9.1 m) radial gates, has a capacity of 172,000 cubic feet per second (4,900 m3/s), and finally the emergency spillway, a 995-foot (303 m) long concrete overflow structure, can discharge more than 300,000 cubic feet per second (8,500 m3/s).[17]”