United States: Exceptional deficits persist in SW states

26 May 2025

THE BIG PICTURE
The forecast for the 12-month period ending in January 2026 indicates that widespread exceptional deficit in the Southwest is expected to mostly resolve, but remain in some portions of California, Nevada, and Utah, and Colorado. Moderate to severe surpluses are expected in some Southern states.

Severe to exceptional deficits are expected in:

Nevada, appearing in portions of Nye County, continuing further south into areas near Las Vegas. These deficits continue into southern California, within San Bernardino County, and into regions along the southern and eastern borders of Utah.
Regions along the borders of western Nebraska, southeastern Wyoming, and northeastern Colorado.
North Carolina, with the most intense deficits occurring in eastern coastal regions of the state, as well as in southern areas near Sunset Beach.
Southern Pennsylvania, near the Tuscarora State Forest.

Moderate to severe surpluses are anticipated in:

Tennessee, in the westernmost parts of the state. These anomalies continue north into much of western and northern Kentucky.
North-central Texas, in areas west of Fort Worth and east of Lubbock, continuing north into southwestern and central Oklahoma.
Central and southeastern Oregon, as well as east-central regions of Washington.
Alaska, in areas within the Denali Borough, the Seward Peninsula, and the North Slope Borough. Moderate surpluses are expected in western and eastern Puerto Rico.

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

FORECAST BREAKDOWN

The forecast through July 2025 indicates that exceptional deficits will persist in southern North Carolina, central Nebraska, western Colorado, eastern Colorado, and southern Arizona. Extreme to exceptional deficits are expected to emerge in southeastern Wisconsin. Moderate to extreme deficits are expected to be widespread throughout the Midwest. Severe to extreme surpluses are expected to persist in north-central Texas, western Tennessee, central to southern Oregon, and northeastern areas of California. Moderate to extreme surpluses are anticipated in southwestern, central, and northern Alaska, as well as much of Puerto Rico. Moderate surpluses are expected to spread throughout southwestern to central Oklahoma and western to northern Kentucky.

From August through October 2025, severe to exceptional deficits will occur in eastern coastal Carolina, southeastern South Carolina, southernmost regions of California, and southwestern Arizona. Moderate deficits are expected to be widespread across much of the Midwest, including areas of South Dakota, Nebraska, Michigan, Illinois, and Indiana. Severe surpluses are expected in central to southern Oregon, east-central Washington, and north-central Texas. Severe to extreme surpluses are also expected in western Tennessee and western to northern Kentucky, as well as northern and central Alaska. Moderate to severe surpluses are anticipated in southwestern to central Oklahoma.

The forecast for the final months – November through January 2026 – expects severe to extreme surpluses in Texas and Oklahoma to dissipate, becoming near-normal conditions. Southeastern Oregon may experience a continuation of moderate to severe surpluses. Moderate to severe deficits are expected in southeastern Wyoming, northeastern Florida, and eastern coastal North Carolina.

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

IMPACTS
Lake Powell, the second-largest reservoir in the U.S., faces another year of low spring runoff as climate stress, dry soils, and insufficient snow retention worsens water supplies in Utah. The prediction illustrates a major decline from earlier forecasts – forecasts initially projected 92% in December, then down to 70% in March. Hydrologist Cody Moser stated that the snowpack and water supply outlook was “off to a promising start December 1, and then basically, since mid-December, we’ve been tracking below-normal above Lake Powell.”

Lake Mead also faces challenging summer conditions as a severely dry winter and rapidly melting snowpack across the Rocky Mountains threaten the reservoir’s strained supply. This year’s snowpack in the Rockies peaked at just 63% of average and melted up to four weeks early. This drastically reduced runoff into the Colorado River, which provides 85% of Lake Mead’s water.

In contrast, Northern Nevada anticipates a healthy water year as early snowpack melt replenishes reservoirs and robust water management systems aid conservation efforts. According to the Truckee Meadows Water Authority (TMWA), representatives anticipate normal river flows and reliable water supply for the rest of 2025. TMWA maintains 80 groundwater wells and aquifer recharge systems in northern Nevada, as well as access to reservoirs storing 27,000 acre-feet of water.

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.

Subscribe to our monthly Water Watch List

Search blog categories

Search blog tags