#ColoradoRiver can no longer sustain Western thirst — Western Farm Press #COriver #aridification

From Western Farm Press (Todd Fitchette):

Back when the Colorado River Compact was being negotiated about 100 years ago, water was not viewed as a problem. Officials deemed there was plenty to go around.

Fast forward a century and the seven Colorado River Basin states – particularly the three lower basin states of California, Arizona, and Nevada – are using more than the system can sustain. Nowhere is this more evident than on the chalk-white dry rims of Lakes Mead and Powell, the two large reservoirs on the system that some fear will hit catastrophically low levels in the next couple years.

Chris Harris, executive director of the Colorado River Board of California, says the basin states must grapple with the “new normal” of reduced flows in a river system once thought to provide ample water for the West…

The 14maf annual average is bookmarked by years of plenty – 15 of them over the last century at over 20maf. Conversely, 44 of those years, or nearly half of that period, produced under 14maf of natural flow at the Lees Ferry Gaging Station in Arizona.

Viewed another way, Harris points to data that show the worst hydrology years on record since 1906 are all in the 21st Century…

The vulnerability of the Colorado River system was seen in a 2012 basin study report showing the average annual natural flow at Lee Ferry of 13.8maf. Some years were much less.

When California alone has access to 4.4 maf and there are years when the unregulated flow into Lake Powell in the upper Colorado River basin is at or below 5maf, “the math doesn’t add up,” he said.

Climate scientists similarly point to water scarcity because of severe drought, and the need for the basin states to “pull together, and that includes California.” Not only must water managers and urban planners consider water-short years that challenge supply, they must manage for the extreme rain events that can damage and destroy flood control infrastructure…

By 2019 California’s use of the Colorado River had fallen to 3.85maf and the following year California had about 1.4maf of “intentionally created storage” (ICS) water banked in Lake Mead for years like the current. This created concerns in Arizona and Nevada as Lake Mead continued to fall and officials there tried to slow the inevitable Tier 1 shortage call by encouraging MWD to not take all its saved water from Lake Mead.

Because California also has access to [Central Valley Project and State Water Project] water, Harris said there are huge incentives for water management there to become sustainable and reduce demand for the Colorado River.

“You take an entity like the Metropolitan Water District of Southern California (MWD), which gets about 2.2maf from the State Water Project; they got 100,000-acre feet this year from the State of California,” he said.