Tempe Town Lake dam proving itself in water release

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(Source: City of Tempe via Facebook) (Source: City of Tempe via Facebook)
Aerial view of water flowing over the dam at Tempe Town Lake on Friday, Feb. 17. (Source: KPHO/KTVK) Aerial view of water flowing over the dam at Tempe Town Lake on Friday, Feb. 17. (Source: KPHO/KTVK)
(Source: City of Tempe via Facebook) (Source: City of Tempe via Facebook)
(Source: City of Tempe via Facebook) (Source: City of Tempe via Facebook)

Between snowmelt making its way down to the Valley and recent rains, Tempe Town Lake is doing exactly what it was designed to do – act like a river.

The City of Tempe tweeted a short video Wednesday afternoon showing the relatively new Tempe Town Lake Western Dam in action.

SRP released the water from upstream – the upper Salt River and Verde River – allowing it to flow through Tempe Town Lake and into the normally dry river channel.

“This is why we built this dam,” Tempe spokeswoman Kris Baxter-Ging during a Facebook Live late Wednesday morning. “It’s safely releasing the water that’s coming from upstream at the Salt River.”

[RELATED: Normally dry Salt River floods Mesa roadway after planned water release]

The flow is slow – about 600 cubic feet per second – which means it’s still safe for boaters to go out on the lake. For perspective, Baxter-Ging described a cubic foot as the size of a basketball and explained that the lake and dam can handle a flow of up to 250,000 cubic feet per second.

“The dam is functioning the way it is intended, lowering to let the water pass through the river channel,” explains her post. “When the flows from upstream stop, the dam raises to maintain the water in the lake.” 

Baxter-Ging said the water release would likely wrap up Thursday.

She also said this is an excellent example of the how the dam, which is the largest hydraulically operated steel-gate dam system in the country, is meant to work.

When Tempe Town Lake was first filled the summer of 1999, it had an inflatable rubber dam system with four bladders on either end.

Because rubber has a limited lifespan, particularly when subjected to extreme heat, the plan was to eventually replace the dam system, but disaster struck before that happened.

One night in July 2010, one of the rubber bladders on the west end of the lake burst, allowing millions of gallons of water to pour unchecked into the river bed. Witnesses said it happened extremely fast. Most of the water was gone within about an hour of the dam rupture, the rest within 24 hours. 

[RELATED: Tempe Town Lake closed for boating, water activities due to Salt River debris]

Plans were already underway to replace the old bladders, but with the bladder burst, the search was on for a system that would be serviceable for years to come.

The City settled on the steel-gate dam system. The new dam, which we are seeing in action now, is expected to last for at least 50 years. The project cost, including removing the old dam, was about $47 million.

The lake was closed while the repairs were effected and then reopened about three months later with a cofferdam in place to allow most of the construction on the new dam to be done while the lake was full. The lake was drained again -- deliberately this time -- in February 2016 for the last phase of the construction.

With the final dam repairs completed and the lake full again, a process that took two weeks by itself, Tempe Town Lake officially reopened on May 6, 2016.

[RELATED: Water flowing into Tempe Town Lake]

Tempe Town Lake, which holds about 880 million gallons of water and is usually 16 feet deep, is about 2 miles long, running from west of McClicktock Road to east of Priest Drive between Rio Salado Parkway and Curry Road.

Copyright 2017 KPHO/KTVK (KPHO Broadcasting Corporation). All rights reserved.

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