U.S. drought conditions have grown more serious in June, drawing concern from climate change experts. The Drought Monitor had predicted that dry conditions would increase in June across western states, which are currently categorized as "exceptional drought," and have encompassed the largest area in 10 years.

"Some states, especially parts of California and parts of the southwest, it's really quite extreme drought conditions," Ben Cook, a climate scientist at NASA's Goddard Institute for Space Studies, told Reuters.

Major reservoirs are reportedly holding about half as much water as they should for this time of year. Jay Lund, a watershed expert at U.C. Davis, told the Sacramento Bee that "we’re starting to chew through the drought storage in our reservoirs."

Lake Mead, the nation's largest reservoir in terms of water capacity, has reached its all-time lowest water level, at under 38% capacity. The 247 square-mile lake in Nevada and Arizona is a major water supply for surrounding states. 

Restrictions on water use are already in place for many southwestern states. The cuts are "a painful reduction to Arizona," Tom Buschatzke, director of the Arizona Department of Water Resources, told NPR.

"If the reservoir continues to decline, more aggressive actions will be taken by the lower basin users, including California, to slow the decline in the system," he said.

Meanwhile, massive wildfires have engulfed eastern Arizona this week, leading Gov. Doug Ducey to issue emergency declarations.

Drought worries have existed in the West for several decades. Drought expert Jeff Marti told NPR that the Northwest hasn't been this dry since the 1920s.

In western states, when cities between Denver and Los Angeles were first growing, it was known that a major water supply would be needed to access such an arid region. Officials had to divide the water supply from the Colorado River between surrounding states but did so when there was above-average precipitation. This led to the overuse of the supply. Hydrologists had warned that the river could not reliably meet future water demands.

Some contributing factors to the dry conditions can be explained by “La Nina” episodes, which is a period of colder conditions when warmer conditions would be expected, as well as the “monsoon season,” which brings the most amount of rain during summer and did not happen in 2020.

Droughts in the west could be the start of a federal water shortage, which would mean water restrictions to several states. These cuts would be expected in August and would impact large areas of farmland out west and Las Vegas at large.  

High temperatures make the opportunity for rainfalls and snowflakes to replenish the water supply harder due to an increased chance of evaporation before it can make any difference. 

A water shortage declaration will be made if the Bureau of Reclamation's August projections show the lake level remaining below 1,075 feet at the start of 2022, according to the Las Vegas Review-Journal.