#LakePowell near historic lows — The Navajo Times #ColoradoRiver #COriver #aridification

Colorado River “Beginnings”. Photo: Brent Gardner-Smith/Aspen Journalism

From The Navajo Times (Krista Allen):

Water levels at Lake Powell, the second-largest reservoir in the country, fell to 3,559.95 feet above sea level on Monday, down from an average of 3,604.09 at this time (May 26) last year, according to the Lake Powell Water Database.

Lake Powell is at 34.2% of full pool (24,322,000 acre-feet) and 140.8 feet below full pool (3,700) as of Wednesday morning.

The primary factors influencing Lake Powell – as well as Lake Mead, the largest reservoir in the country – are inflows into Lake Powell, according to the Bureau of Reclamation.

Upper Basin hydrology accounts for about 92% of the total streamflow in the basin. Inflow into Lake Powell is also affected by Upper Basin water use and the operation of reservoirs above Lake Powell…

The Colorado River, Tooh Bikooh Dinék’ehjígo, originates on the Colorado western slope. Over 25 significant tributaries join it. The Green River in Utah is the largest by both length and discharge.

Tooh Bikooh flows to the Gulf of California. It provides water to nearly 40 million people for municipal use, to irrigate nearly 5.5 million acres of land, and is the lifeblood for at least 22 federally recognized tribes, seven national wildlife refuges, four national recreation areas, and 11 national parks, according to Reclamation.

In August 2020, a 24-month study projected the Jan. 1, 2021, Lake Powell elevation below the 2021 Equalization Elevation of 3,659 feet and above 3,575 feet. The lake level was 3,582.06 feet that day, according to the Lake Powell Water Database.

With an 8.23-million-acre-foot release from Lake Powell in the water year 2021, an April 2021 24-month study projects the end-of-water-year elevation here below 3,575 feet. Lake Powell will continue to release 8.23 million acre-feet through the remainder of the water year.

The Bureau of Reclamation will release its subsequent major study in August…

The current water level at Mead is 1,074.84, which is 154.16 feet below the full pool of 1,229 feet, as of Wednesday morning.

Arizona, Nevada, and Mexico are making contributions to Mead in a collaborative effort to maintain water levels and avoid severe shortage conditions at least through 2022.

But a first-ever official shortage declaration from the Department of the Interior is almost certain later this year…

Because Tooh Bikooh is over-allocated – and because drought and climate change are likely to worsen as the region gets hotter and drier — the seven Colorado River Basin states in 2019 agreed on a plan to manage the river by voluntarily cutting their water use to prevent the federal government from imposing mandatory water restrictions on the supply.

As part of the Lower Basin’s drought contingency plan, the CAP would see its water supply cut by about one-third in 2022 because of its junior water rights in the river’s water. And farms in central Arizona would experience those water cuts.

Reclamation’s projections continue to show a very high likelihood of Tier 1 reductions in 2022 and in 2023, as well as an increased risk of Tier 2 conditions in the future, according to the CAP.

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