Despite Rain Storms, California Is Still in Drought
A rapid string of punishing storm systems, known as atmospheric rivers, has brought extreme amounts of rain and snow to California during the past weeks, but the sudden deluge has not made up for years of ongoing drought.
Recent Rains Haven’t Erased Long-Term Drought
Precipitation compared with a 1991-2020 average.
110
30%
50
70
90
150
200
300
400
Short-term view:
Past month
Long-term view:
Past 3 years
Redding
Redding
Sacramento
Sacramento
San Francisco
San Francisco
Fresno
Fresno
Los Angeles
Los Angeles
San Diego
San Diego
110
30%
50
70
90
150
200
300
400
Short-term view:
Past month
Long-term view:
Past 3 years
Redding
Redding
Sacramento
Sacramento
San Francisco
San Francisco
Fresno
Fresno
Los Angeles
Los Angeles
San Diego
San Diego
110
30%
50
70
90
150
200
300
400
Short-term view:
Past month
Long-term view:
Past 3 years
Redding
Redding
Sacramento
Sacramento
San Francisco
San Francisco
Fresno
Fresno
Los Angeles
Los Angeles
San Diego
San Diego
110
30%
50
70
90
150
200
300
400
Short-term view:
Past month
Redding
Sacramento
San Francisco
Fresno
Los Angeles
San Diego
Long-term view:
Past 3 years
Redding
Sacramento
San Francisco
Fresno
Los Angeles
San Diego
110
30%
50
70
90
150
200
300
400
Short-term view:
Past month
Redding
Sacramento
San Francisco
Fresno
Los Angeles
San Diego
Long-term view:
Past 3 years
Redding
Sacramento
San Francisco
Fresno
Los Angeles
San Diego
110
30%
50
70
90
150
200
300
400
Short-term view:
Past month
Long-term view:
Past 3 years
Redding
Redding
Sacramento
Sacramento
San Francisco
San Francisco
Fresno
Fresno
Los Angeles
Los Angeles
San Diego
San Diego
The storms inflicted widespread flooding and killed at least 20 people. The onslaught of precipitation also started to refill reservoirs and pile up snowpack in the Sierra Nevada.
Simultaneous flooding and drought are “basically a byproduct of the high variability of California’s climate,” said Jay Lund, co-director of the Center for Watershed Sciences at the University of California, Davis.
The state typically gets its precipitation during the late fall and winter, much of it from storms fueled by atmospheric rivers, and can go long periods of time in the spring and summer without any rain.
California has built its water infrastructure — reservoirs, wells and irrigation systems — in part to account for the imbalanced timing in precipitation. However, the state’s strategy of capturing water during wet periods and reserving it for dry periods gets “more difficult to implement because of the extremes becoming greater” in a warming climate, Dr. Lund said.
The recent rains resulted in a quick and heavy influx of water into many of the state’s reservoirs. Many have returned to or surpassed average levels, but few are at full capacity.
California’s Reservoirs Closer to Recovery
Some reservoir levels are near their historical averages but below capacity.
Shasta
SHASTA
RESERVOIR CAPACITY
OROVILLE
Sacramento
Oroville
HISTORICAL
AVERAGE
San Francisco
PINE FLAT
SAN LUIS
PYRAMID LAKE
52% of capacity
Los Angeles
83% average
57% capacity
San Luis
104% average
2022-23
RESERVOIR LEVELS
44% capacity
Pine Flat
64% average
47% capacity
125% average
86% of capacity
Pyramid Lake
94% average
Jan.
2022
Jan.
2023
Jan.
2022
Jan.
2023
Jan.
2022
Jan.
2023
Jan.
2022
Jan.
2023
Jan.
2022
Jan.
2023
Shasta
SHASTA
RESERVOIR CAPACITY
OROVILLE
Sacramento
Oroville
HISTORICAL
AVERAGE
San Francisco
PINE FLAT
PYRAMID LAKE
52% of capacity
Los Angeles
83% average
57% capacity
104% average
2022-23
RESERVOIR LEVELS
Pine Flat
47% capacity
125% average
86% of capacity
Pyramid Lake
94% average
Jan.
2022
Jan.
2023
Jan.
2022
Jan.
2023
Jan.
2022
Jan.
2023
Jan.
2022
Jan.
2023
Shasta
SHASTA
RESERVOIR CAPACITY
OROVILLE
Sacramento
Oroville
San Francisco
PINE FLAT
HISTORICAL
AVERAGE
PYRAMID LAKE
Los Angeles
52% of capacity
83% average
57% capacity
104% average
2022-23
RESERVOIR
LEVELS
Pine Flat
47% capacity
125% average
Pyramid
Lake
86% of capacity
94% average
Jan.
2022
Jan.
2023
Jan.
2022
Jan.
2023
Jan.
2022
Jan.
2023
Jan.
2022
Jan.
2023
Shasta
SHASTA
RESERVOIR CAPACITY
OROVILLE
Sacramento
Oroville
San Francisco
PINE FLAT
HISTORICAL
AVERAGE
PYRAMID LAKE
Los Angeles
52% of capacity
83% average
57% capacity
104% average
2022-23
RESERVOIR
LEVELS
Pine Flat
86% of capacity
47% capacity
94% average
125% average
Pyramid Lake
Jan.
2022
Jan.
2023
Jan.
2022
Jan.
2023
Jan.
2022
Jan.
2023
Jan.
2022
Jan.
2023
Oroville
RESERVOIR CAPACITY
OROVILLE
Sacramento
San Francisco
PINE FLAT
PYRAMID LAKE
HISTORICAL
AVERAGE
Los Angeles
57% capacity
104% average
2022-23
RESERVOIR
LEVELS
Pine Flat
47% capacity
125% average
Pyramid
Lake
86% of capacity
94% average
Jan.
2022
Jan.
2023
Jan.
2022
Jan.
2023
Jan.
2022
Jan.
2023
Oroville
RESERVOIR
CAPACITY
OROVILLE
Sacramento
San Francisco
PINE FLAT
HISTORICAL
AVERAGE
PYRAMID LAKE
Los Angeles
57% capacity
104% average
2022-23
RESERVOIR
LEVELS
Pine Flat
47% capacity
86% of capacity
125% average
94% average
Pyramid Lake
Jan.
2022
Jan.
2023
Jan.
2022
Jan.
2023
Jan.
2022
Jan.
2023
If reservoir levels continue to creep up above average levels, it could alleviate some deficits that have accumulated over consecutive extreme drought years, said Molly White, an operations manager for the California State Water Project.
“It all helps the overall drought picture,” she added.
California has a naturally variable climate: Periods of drought are punctuated by periods of wetter weather. But research suggests that global warming caused by greenhouse gas emissions is making it more likely that any given drought will persist or become more intense, and less likely that any string of wet years will continue.
Climate change will also worsen the wettest extremes. Because warmer air can carry more moisture, atmospheric rivers, which are essentially long plumes of water vapor, will also be able to unleash larger cargoes of precipitation.
The winter is typically the rainy season for California, the time of year when many of the state’s aquifers get recharged with precipitation. But snowmelt that begins in the spring and continues throughout the summer is crucial in refilling aquifers, too, typically providing about 30 percent of the water supply for the state.
The recent storm systems have been the biggest contributor to the snow accumulation in the Sierra Nevada so far this winter. A number of monitoring stations have measured record amounts of snow water equivalent (the amount of liquid water available in snow) for this time of year, reaching seasonal highs usually not seen until late April, when snowpack usually peaks.
On Jan. 17, the recorded snow water equivalent was double what it was last year on the same date, according to data from the California Department of Water Resources.
Storms Build Up California’s Snowpack
Average snowpack levels statewide reached seasonal highs usually not seen until April.
45
Previous years since 2003
40
35
This year
30
25
20
15
Last year
10
5 inches
Aug.
April
June
Feb.
Dec.
Oct.
Oct.
45 inches
Previous years since 2003
40
35
This year
30
25
20
15
Last year
10
5
Feb.
June
Oct.
Oct.
45
Previous years since 2003
40
35
This year
30
25
20
15
Last year
10
5 inches
Aug.
April
June
Feb.
Dec.
Oct.
Oct.
Atmospheric rivers don’t always bring more snow; storms can actually shrink the snowpack if precipitation falls as rain instead of snow at high elevations. That may happen more frequently as the climate continues to warm.
“Snowpack is in pretty good shape right now,” said Rich Tinker, a meteorologist at the National Weather Service and an author on the latest U.S. Drought Monitor report. “But how it melts is going to be important.” Snow melt usually happens in a slow, stable way, but if temperatures rise quickly, that stability can change, he said.
Last year, an unusually wet early winter ultimately gave way to several dry months that led to restrictions on water use in the summer. Research shows that climate warming and unseasonably warm temperatures in the spring and summer have contributed to an earlier thaw season and more rapid melting.
California’s recent spate of storms will not reverse three years that have been the state’s driest on record. It’s taken multiple years to get to the current state of persistent drought, said Gus Goodbody, a hydrologist at the United States Department of Agriculture’s National Water and Climate Center. “It’s going to be hard for a single season to counteract that.”