California is emerging from its driest 12-month period in nearly a century, and catching its reservoirs up will be difficult even if it sees a historically wet winter.
The state experienced its lowest level of statewide precipitation since 1924 during Water Year 2021, which spanned Oct. 1, 2020, to Sept. 30, driving the dry conditions that fuel wildfires and simultaneously straining resources to make fighting them more difficult.
A recent report from the California Department of Water Resources assesses Water Year 2021, and it puts hard data to the shortages the state has been experiencing all year long, with total rainfall and snowmelt falling woefully behind historical averages.
Storage in Nevada's Lake Mead — a lake that provides water to millions of people in California, Arizona, Nevada, and Mexico — and Lake Powell reached new record lows. In addition, several regions saw less than half of their average annual precipitation, including major cities such as San Francisco and Los Angeles, as well as Sacramento, Bakersfield, and Santa Barbara.
California's reservoirs were in good shape going into Water Year 2021, following an above-normal year in 2019 that carried through 2020. However, dry conditions in recent months triggered a drawdown of the state's reservoir storage to 60% of its average by the end of the water year, and researchers detect a trend.
"Extreme conditions that once were rare are occurring with increased frequency. California’s climate is transitioning to a warmer setting in which historical relationships among temperature, precipitation, and runoff are changing," the department's report said.
The authors also explained the volatile climate's effect on projection-making, saying that it is becoming "increasingly difficult" for forecasters to rely on historical data to develop water supply predictions and note how they got burned by overestimating snowmelt runoff for Water Year 2021 by 68% for one region.
For that reason, the authors withhold forecasts for rain and snowmelt over the next five months, during which the state has historically gotten about 75% of its annual precipitation. But only an extraordinarily wet winter would bring water runoff levels back to where they have been historically.
"When precipitation occurs under conditions of severe moisture deficit, an increased amount of that precipitation replenishes depleted soil moisture and is taken up by vegetation, reducing runoff efficiency," the report said, adding, "For the upper Colorado River Basin (the watershed tributary to Lake Powell), an estimated 165% of average annual precipitation would be needed to achieve average runoff."
California's water resources strain led Gov. Gavin Newsom to introduce emergency drought proclamations in April and May for multiple counties. Newsom then expanded the emergency again in July, bringing the number of covered counties to 50.
Newsom also signed an executive order promoting water conservation, pitching it as "a way of life" in California. He urged residents to take "commonsense" water use reduction measures, such as lowering irrigation volume and shortening shower times.
"We are hopeful the people of the state of California will take that mindset brought into the last drought and extend that forward with a 15% voluntary reduction," Newsom said during a July press conference near San Luis Obispo at Lopez Lake, which provides drinking water to Arroyo Grande, Grover Beach, Pismo Beach, Oceano, and Avila Beach. The lake fell to about one-third of its capacity during the summer and remains 31% full.
Newsom emphasized at the time that the conservation recommendations, which were directed at residences, business, and agricultural operations, were voluntary and not representative of a "nanny state."
"We are not trying to be oppressive," he said.
In his fourth action in seven months, on Oct. 19, Newsom expanded his drought emergency proclamation to the remaining eight counties to cover the entire state.
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Original Author: Jeremy Beaman
Original Location: Drought-stricken California suffers the driest year in nearly a century
Source : https://news.yahoo.com/drought-stricken-california-suffers-driest-030000818.html722