Historic drought conditions are continuing to affect Western states, despite winter weather that included major snowstorms and a high-impact atmospheric river. In 2020, the U.S. slipped into the most widespread drought since the summer of 2013, with about half of the country experiencing some level of drought. With many areas in the Western U.S. in drought for more than 12 consecutive months, it underscores that drought is now more of a rule rather than an exception.
The Palmer Hydrological Drought Index (PHDI) measures droughts and their long-term, hydrologic impacts, like their effects on groundwater and reservoir levels. According to the 24-month average PHDI index, the Western U.S. has experienced drought in 17 of the past 20 years. A huge part of the West has been in consistent drought for a year, including Arizona, Colorado, and northern California.
But it’s not just the West this year. According to the April 1st release of the U.S. Drought Monitor, 44% of the contiguous states are in moderate drought or worse conditions, signaling potential trouble to water supplies for municipalities, agriculture, and recreation:
- West – A majority (59%) of the area is experiencing severe drought or worse. About 21% of the region is in exceptional drought, the most intense drought condition, mostly concentrated in Southwestern states.
- High Plains – 40% of the area is currently in severe drought or worse.
- Midwest – Nearly half (47%) of the area is abnormally dry, and 12% is experiencing moderate drought or worse. In Iowa, 8% of the state has severe drought conditions or worse; 39% of Minnesota is in moderate drought.
- South – More than a third (37%) of the area is considered to be in moderate drought, mostly coinciding with the area in and around Texas. More than two-thirds of Texas (69%) is experiencing moderate drought or worse, with 20% of the state in extreme drought.
Melting snowpack provides an essential water supply to rivers and reservoirs in the Western U.S in their drier summer months. Due to climate change, more winter precipitation falls as rain and, as a result, snowpack has diminished rapidly in the West, becoming less reliable. According to a 2018 study, there has been a 15-30% average decline in the amount of water stored as snowpack, as measured on April 1st (known as the snow water equivalent), across the West since 1955.
Moreover, groundwater supplies that act as a buffer in bad years are becoming depleted. The rate of water withdrawal outpaces the rate at which they are recharged by rainfall, creating an increasingly unsustainable situation which is only worsened by climate change. Once they develop, these impacts take a long time to recover from.
At over $9 billion per event, drought has the second-highest price tag of any type of billion-dollar disaster event since 1980—damaging crops, reducing the efficiency of thermoelectric power generation, threatening outdoor recreation and tourism industries, and degrading ecosystems. Parched rangelands and forests also increase the fuel for wildfires, making for dangerous conditions for vulnerable species and nearby communities. In addition to combating climate change, sustainable water management strategies need to be implemented to maintain water security — in the U.S. and beyond.