Southwest Drought?

By: Icecap.us
By: Icecap.us

Science magazine claims in a recent article (attached) by Benjamin Somers and Becky Ham: “Drought in the American Southwest, already decades old, could soon be exacerbated as rainfall plummets.”

Yet according to the people who really know and work with the data every day and not models, Roosevelt Lake in Arizona has reached highest level ever and the all time record level is even prompting SRP water releases. See this story at icecap.us and see the improvement since 2002.

What’s turned into an unexpected second consecutive wet La Nina winter has brought the level at Roosevelt Lake to its highest-ever elevation. And with another bountiful winter runoff comes another first for SRP, storage limitations, which have required the release of water into the Salt River through the Valley.

With the four reservoirs on the Salt River all nearly full, additional precipitation or runoff from melting snow has brought the elevation of Roosevelt Lake into uncharted territory—and with it a second consecutive runoff year of excess water releases into the Salt River.

On Friday, Feb. 27, Roosevelt Lake’s elevation exceeded 2,151 feet. Water storage at elevations greater than 2,151 feet - which is considered full - is designated as Flood Control Space, as regulated by the Army Corps of Engineers’ Water Control Manual. The Corps’ Water Control Manual specifies release rates during the rising and falling stages of storage at Roosevelt Lake and a 20-day drawdown period to meet environmental requirements.

Release impacts river crossing
The water releases are having an impact on Valley residents. Water being spilled from Granite Reef Diversion Dam east of Mesa is moving west down the Salt River and has closed the river crossing at McKellips Road. This closure likely will last through the spring.

Reservoirs filling to record levels
Now at this all-time high elevation, New Conservation Storage space has been completely filled. This consists 272,500 acre-feet of space behind Theodore Roosevelt Dam that is allocated for the Valley cities of Chandler, Glendale, Mesa, Phoenix, Scottsdale and Tempe. This is the third time water has been stored in this space since the completion of a modification project in 1996 that raised the dam 77 feet, but the first time the entire space has filled.

December storms produced one of the wettest Decembers in SRP history, when more than 4.3 inches of precipitation fell on the Salt and Verde watersheds. That total ranks as the 11th highest on record during the past 110 years. The median amount of precipitation for the December-through-March period is 6.25 inches, which means nearly 70% of the median was achieved in December alone. February storms dropped another 2 inches on the watershed.

The wet La Nina runoff season has significantly improved SRP’s water-supply situation. The reservoir system on the Salt and Verde rivers stands at 96% of capacity, compared to 92% a year ago. Roosevelt Lake, which holds about 70% of SRP’s reservoir system storage capacity, has reached 100% “Capturing water in wet years for use in dry years means the SRP reservoir system is doing exactly what it was designed to do” said Charlie Ester, Manager of Water Resource Operations.

(Icecap note: Hat tip to Mark Albright who notes “I also know of no significant evidence or impact of climate change in the Pacific Northwest. The reality of climate change and the hysteria of climate change are now miles apart.)


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