United States: Widespread water deficits in the West

22 June 2021

THE BIG PICTURE
The 12-month forecast ending February 2022 indicates widespread water deficits of varying intensity in the U.S. West, Pacific Northwest, and Rocky Mountains. Deficits will be exceptional in many pockets including Arizona’s southwest quadrant, Southern California, the Bay Area and Sacramento, the California-Oregon border, and the Salmon River region of Idaho.

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Deficits on the Colorado River will be extreme to exceptional surrounding Lake Mead and severe in the river’s upper basin. Moderate to severe deficits are forecast for western Colorado, northeastern Wyoming, pockets in Montana, and northeastern North Dakota.

Surpluses are forecast in the lower regions of the Mississippi River’s many tributaries, generally moderate in Tennessee, southern Missouri, Arkansas, eastern Oklahoma, northern Mississippi, and northern Alabama. However, surpluses will be more intense in the Gulf region of Louisiana and Mississippi. Moderate to exceptional surpluses are expected in East Texas and moderate surpluses west of Fort Worth and from Corpus Christi along the coast reaching inland. Elsewhere in the nation, surpluses are forecast through southern Nebraska into Colorado along the Republican River, and in a pocket of north-central Kansas.

In the Great Lakes Region, deficits are forecast in Michigan, central Wisconsin, and a few small, isolated pockets in Minnesota. Western Pennsylvania, too, can expect some pockets of deficit. Along the St. Lawrence River in Upstate New York deficits will be intense, while deficits of varying intensity are forecast in Vermont, New Hampshire, and southern and eastern Maine.

Some pockets of deficit are forecast along the coastal region spanning the shared border of the Carolinas. In Florida, moderate deficits are expected between Jacksonville and Orlando and just north of Lake Okeechobee, but deficits will be more intense south of the lake.

Outside the contiguous U.S., moderate to severe deficits are forecast for Puerto Rico. In Hawaii, surpluses are expected in Oahu and Molokai, deficits in Maui and eastern Hawaii. Alaska can expect deficits in the northeast, in a large block east of Norton Sound, and near Anchorage and Valdez. Surpluses are forecast west of Bethel, near Iliamna Lake, in the eastern Alaska Range, and near Juneau.

FORECAST BREAKDOWN
The 3-month maps (below) show the evolving conditions in more detail.

The forecast through August indicates widespread deficits in the West, Rockies, Pacific Northwest, Great Lakes, and Northeast, and widespread surpluses fanning from the Gulf region in Louisiana. Deficits will be exceptional in many regions, notably Northern California, western Oregon, and the Utah Rockies. Moderate deficits will increase in Montana but deficits in the Dakotas will shrink and downgrade. Deficits are forecast throughout Michigan, emerging in the Upper Peninsula, and will include intense anomalies. Moderate deficits will increase in Wisconsin and Minnesota while shrinking in Iowa and in the Upper Ohio River Basin. Intense deficits are expected in Upstate New York and New England, while deficits from Pennsylvania through the Carolinas and in Florida shrink and downgrade.

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Surpluses will increase and intensify in the South from eastern Texas through Alabama with extreme to exceptional anomalies in Texas and Louisiana. Surpluses of lesser intensity will reach into Oklahoma, Arkansas, southern Missouri, and Tennessee. Elsewhere, surpluses are forecast through southern Nebraska along the Republican River into Colorado and in a pocket of north-central Kansas.

From September through November deficits and surpluses will shrink considerably. Deficits will remain intense in a few areas including Idaho’s Salmon River region and northern Utah. Other areas of deficit include California, Oregon, eastern Washington, western Montana, western Wyoming, western Colorado, and northern Michigan. Surpluses are forecast for southern Nebraska into Colorado and north-central Kansas, southern Missouri and northern Arkansas, central Oklahoma, and Ft. Worth, Texas and the Brazos River region to the west.

The forecast for the final months – December 2021 through February 2022 – indicates surplus conditions from eastern Kansas through the northern Ohio River Basin, Michigan, and into New England. Deficits will persist in Idaho and southwestern Colorado into Utah. Pockets of surplus will emerge in the Pacific Northwest and small pockets in the West.

Please note that WSIM forecast skill declines with longer lead times.

IMPACTS
By mid-June, over 97 percent of the U.S. West was in some stage of drought, as reported by the U.S. Drought Monitor, including 100 percent of California.

In the San Francisco Bay Area, mandatory water restrictions affecting 2 million people have been implemented to address shortages.

Along the California-Oregon Border, the Klamath Project, a water diversion project that redirects water from natural waterways like Upper Klamath Lake to agricultural systems, has suspended water flow to irrigators. The move threatens to further polarize relations between Native Americans dependent on local fishing and farmers in the region, with no evident winners likely during this extended drought.

Lake Mead, the reservoir formed by the Hoover Dam on the Colorado River, dropped to a record-breaking low on 10 June, threatening the water supply to 25 million people.

Nevada’s state legislature has enacted a law prohibiting ‘non-functional’ grass in the jurisdiction of the Southern Nevada Water Authority, over 30 percent of the grass in the Las Vegas area, to conserve limited water resources.

For the third time in just a year, Utah’s governor has issued an official drought declaration for the state as conditions plummet to their worst on record. The declaration calls on municipalities to create and enforce water restrictions, and fireworks are banned on state lands.

But as the West suffers from lack of water, Tropical Storm Claudette has torn into the U.S. Gulf Region dumping 15 inches of rain, killing 15 people as it blew through Louisiana, Alabama, Mississippi, and the Florida Panhandle.

NOTE ON ADMINISTRATIVE BOUNDARIES
There are numerous regions around the world where country borders are contested. ISciences depicts country boundaries on these maps solely to provide some geographic context. The boundaries are nominal, not legal, descriptions of each entity. The use of these boundaries does not imply any judgement on the legal status of any territory, or any endorsement or acceptance of disputed boundaries on the part of ISciences or our data providers.

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