It’s a stark view.
Both U.S. and European satellites have captured the profound changes in drought-stricken, continually warming California. The last two years have been the driest such period in over four decades, and the paucity of water is easily apparent in the state’s dropping reservoir levels.
California’s critical mountain snowpack — which ultimately feeds much of its reservoir system — is below average and trending down, but that’s not the only problem. In a warmer climate, less water flows into reservoirs as more of it evaporates or soaks into the parched ground. The Golden State is losing “runoff efficiency.”
“The decrease in runoff efficiency (the runoff that occurs in response to a given quantity of precipitation) is a troubling, yet expected, outcome of a warming climate,” the California Department of Water Resources wrote in mid-June in response to the worsening drought and low reservoir levels.
Western heat waves, which are growing more intense as the climate warms, make matters worse. Droughts feed off heat.
“Drought and heat are natural dance partners,” NOAA meteorologist Tom Di Liberto recently wrote. “Drought conditions are made more likely or more extreme when temperatures soar. And vice versa, hot temperatures can be made even hotter by a drought-stricken landscape.”
Most of California is mired in either extreme or exceptional drought. Take a look at the telltale “bathtub rings” around the reservoirs below.
Shasta Lake, California’s largest reservoir
As of mid-June 2021, the reservoir was at half of its typical levels for that time of year.
The Shasta Lake reservoir, California’s largest, on July 13, 2019
Credit: usgs / nasa
The Shasta Lake reservoir, California’s largest, on June 16, 2021
Credit: USGS / Nasa
This massive reservoir, a critical part of California’s water infrastructure that opened in 1967, may fall to such low levels this summer that its hydroelectric power plant temporarily shuts down.
Seen on right, the Lake Oroville reservoir was at just 35 percent capacity in June 2021.
Credit: usgs / nasa
Los Angeles Reservoirs
Reservoirs in Angeles National Forest are running low. Seen from space, the San Gabriel Reservoir is largely dried up.
Filled reservoirs in Angeles National Forest in June 2020
Credit: European Space agency
Lower or depleted reservoirs in Angeles National Forest in June 2021
Credit: EUROPEAN SPACE AGENCY