The West’s historic drought in 3 maps

CNN

By John Keefe, Rachel Ramirez and Angela Fritz, CNN

After months of unrelenting drought, precipitation is bringing minor relief to the West, particularly in the Pacific Northwest and northern California.

While some of the drought and fire conditions have been alleviated, the rain and snow has not yet been enough to replenish reservoirs, and the long-term impacts of drought persist.

More than 91 percent of the West is still in drought, according to the US Drought Monitor, with five states entirely in drought conditions: California, Nevada, Idaho, Utah, and Montana. Experts say La Niña conditions could exacerbate the drought, particularly in the Southwest.

Scientists say the West’s 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.

Drought map

California drought remains significant, with the entire state under drought conditions. Still, recent much-needed rain has reduced the area of the state in the highest two drought categories to their lowest points since June 1, according to the Drought Monitor. Other parts of the West have also reaped the benefits of recent precipitation, the agency reports.

The historic drought has strained water resources. The US Bureau of Reclamation said in September that there’s a 3% chance 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 bureau’s projection.

There is also a 66% chance that Lake Mead could drop below the critical threshold of 1,025 feet above sea level in 2025, the bureau said. 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.

The bureau 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 alarmingly high temperatures. Less rain and increasing heat waves have led directly to drought conditions and water shortages.

Though recent rain certainly helped alleviate some of the short-term drought conditions, the latest updated from the Drought Monitor said groundwater and reservoir levels are slow to respond, and that more precipitation this season is needed to fully recharge them.

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.

But now that the rainy season has begun, streamflows in the West are improving, according to the Drought Monitor. Soil moisture and stream flows have improved for many areas in the central and northern Great Basin, including in parts of Idaho, Nevada, and Utah.

Meanwhile, snowpack has also started to form across the northern Rockies as well as the Cascades, and even into parts of the Sierra Nevada, “but it is still early in the season to reap the benefits,” the Drought Monitor noted.

Changes in streamflow affect the water supply for municipal use such as drinking and bathing, crop irrigation and power generation.

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CNN’s Brandon Miller contributed to this report.