The West's historic drought in 3 maps

Updated 11:00 AM ET, Thu September 23, 2021

(CNN)As the North American monsoon season comes to an end, more than 94 percent of the Western states still remain in drought conditions this week, according to the US Drought Monitor, with six states entirely in drought status: California, Nevada, Oregon, Idaho, Utah, and Montana.

Parts of the West, particularly the northern Rockies and the Pacific Northwest, saw record-setting rainfall that brought some slight relief to the region, but most areas remain dry.
Against the backdrop of climate change-fueled drought, wildfires continue to scar in the region: The KNP Complex, a 28,000-acre, lightning-sparked fire, was burning in California's Sequoia National Park, while the Windy Fire, also ignited by lightning, chars more than 31,000 acres in areas including the Tule River Indian Reservation and the Sequoia National Forest.
In addition, new projections from the US Bureau of Reclamation show major reservoirs in the West such as Lake Powell and Lake Mead continuing to drain to historic lows, which could endanger hydropower generation in coming years.
Scientists say the historic, multi-year drought is a clear sign of how the climate crisis is affecting not only the weather, but water supply, food production and electricity generation.

Current drought

Across the West, drought that is categorized as severe or worse is at 80%, the lowest in three months, down from 88% last month. Exceptional drought, the most intense category, is down to 21% and as low as it has been in all of 2021. This is mainly due to improvements in the Southwest, where the monsoon rainfall improved drought conditions, the US Drought Monitor reports.
In Arizona, more than 50% of the state was in exceptional drought three months ago, but now there is no exceptional drought in the state.
California drought remains significant and there has been little chance in the past few weeks, with 100% of the state in drought and nearly half in exceptional drought conditions.
Drought conditions continue to strain water resources. The new modeling from USBR shows a 3% chance that Lake Powell, a major reservoir on the Colorado River, could drop below the minimum level needed to allow the lake's Glen Canyon Dam to generate hydroelectricity next year. In 2023, the chance of a shutdown grows to 34%, according to the projection.
For its neighboring reservoir Lake Mead, the largest in the nation, the updated projections now show a 66% chance that Lake Mead could drop below the critical threshold of 1,025 feet above sea level in 2025. If water levels stay below that critical threshold, it would trigger deep water cuts, potentially affecting millions of people in California, Arizona, Nevada and Mexico.
Already, the Bureau of Reclamation in August declared a water shortage on the Colorado River for the first time, triggering mandatory water consumption cuts for states in the Southwest beginning in 2022.
As the planet warms, drought and extreme heat will also fuel deadly wildfires. Multiple studies have linked rising carbon dioxide emissions and high temperatures to increased acreage of burning across the West, particularly in California.

Rainfall outlook

The West experienced extremely low rain and snowfall over the past year, compounded by drastically high temperatures. Less rain and increasing heat waves have led directly to drought conditions and water shortages.
The end of the monsoon season, which had brought some short-term relief to the drought in the Southwest US, comes roughly on schedule, but the amount of rainfall across much of Arizona, New Mexico and Colorado was well above average.
The robust rainfall this summer eased drought conditions in Southwest states, "but left significant, underlying long-term drought issues such as groundwater depletion and low reservoir levels," according to the US Drought Monitor.
As climate change accelerates and winter temperatures increase, snowfall will decrease. High-elevation snowpack serves as a natural reservoir that eases drought, storing water through the winter months and slowly releasing it through the spring melting season.

Stream and river flow

Streamflow, a measure of how much water is carried by rivers and streams, is another significant indicator of drought and its impact.
As drought conditions have worsened in 2021, hundreds of stream and river locations are experiencing below-average flow. Fishing restrictions have also been put in place on many rivers in Montana due to low flows and warm waters.
Changes in streamflow affect the water supply for municipal use such as drinking and bathing, crop irrigation and power generation.