See the West’s historic drought in 3 maps
John Keefe, Rachel Ramirez and Angela Fritz, CNN
(CNN) — Weeks of monsoon rains have led to drought relief for parts of the Southwest, particularly in Arizona, New Mexico and Utah. But dry and windy conditions continue to drive and worsen wildfires that have been burning parts of the Western states, particularly California, for weeks.
Seven states remain entirely in drought as of Thursday — California, Nevada, Oregon, Idaho, Utah, Montana, and North Dakota — and more than 94 percent of the region is in some level of drought, according to the US Drought Monitor. (See map above.)
Against the backdrop of climate change-fueled drought, the Caldor Fire has been torching more acres for nearly three weeks, threatening the popular tourist city of South Lake Tahoe as it marches toward Nevada’s border.
Scientists say the 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.
In concert with the intensifying fire conditions, the ongoing drought in California continues to strain the state’s water resources. The levels of California’s two largest reservoirs — Lake Shasta and Lake Oroville — are currently at 43% and 34% of their historical averages, respectively. In the Southwest, Lake Powell is currently 31% full and Lake Mead is 35% full. The total Lower Colorado system is 40% full, compared to 50% full at the same time last year.
The US 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, as climate change-fueled drought pushes the level in Lake Mead to unprecedented lows.
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.
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.
Rain in parts of Arizona, New Mexico, Utah, and Montana helped stave off any expansion of drought areas this week.
“Some improvements were made in New Mexico and Utah in response to the cumulative impact of this summer’s active monsoon and its associated short-term improvements to vegetative health, soil moisture, and streamflow activity,” 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.