‘Wonderful’ water year in California: Rain and snow have brought the state’s reservoirs to 128% of historical averages

California ended its “miracle” water year on Saturday with enough rain and snow to fill the state’s reservoirs to 128% of their historical average, making it one of the wettest years in the state’s history.

That’s a welcome boon for a state that has spent much of the past 12 years in a severe drought, forcing state leaders to grapple with how the state should share and manage its water going forward. A series of winter storms in early 2023 ended the state’s recent dry spell.

State officials measured 33.56 inches (85.2 centimeters) of precipitation through the end of September. California’s “water year” begins on October 1st each year, so it can include all fall and winter months when California receives the majority of its rain and snow. The state relies on these wet months to fill its reservoirs, which provide water throughout the state for drinking, agricultural and environmental purposes.

Due to an extreme drought, these reservoirs have fallen to dangerously low levels in recent years. This led to water restrictions for households and businesses and reduced supplies to farmers. It also threatened already endangered fish species, including salmon, which require cold water in rivers to survive.

But the State Water Project — which includes 30 reservoirs and storage facilities and provides water to 27 million people — reported 27.4 million acre-feet in its reservoirs as of Sept. 30. One acre-foot of water is enough to sustain two families of four for a year.

“This was as close to a miracle year as you could get,” said Karla Nemeth, director of the California Department of Water Resources.

The reservoirs were helped by a series of nine strong storms that hit California over the winter. These storms carried so much rain and snow that they were called “atmospheric rivers.” They caused widespread flooding across the state and were blamed for several deaths.

The storms also dumped tons of snow on the mountains. The state’s snowpack as of April 1 was 237% above its historical average. It’s only the fourth time since 1950 that the state’s snowpack has exceeded 200% of average, according to Michael Anderson, the state’s climatologist.

All the snow melted in the spring and summer, filling rushing rivers and reservoirs. Water levels at Lake Oroville rose 240 feet (73 meters) between December 1, 2022 and the end of snowmelt. This is the largest single-season storage increase since the reservoir opened in 1968, according to Ted Craddock, deputy director of the State Water Project.

State and federal officials will need to drain some of the reservoirs to make room for more water expected this year. The state’s rainy season could be complicated by El Nino – the natural, temporary and occasional warming of a portion of the Pacific Ocean. El Nino influences weather patterns around the world. Typically, California experiences more rain and snow during an El Niño year. According to the National Oceanic and Atmospheric Administration, there is a 56% chance that this year’s El Niño will be considered strong and a 25% chance that it will reach supersized proportions.

The potential for more strong storms this year, particularly along the coast, “keeps me up a little at night,” said Gary Lippner, deputy director of flood management and dam safety for the California Department of Water Resources.

“We simply don’t have extensive flood systems on the coast of California,” he said. “This is an area we are paying particular attention to.”

All the rain and snow this year may have contributed to the smaller wildfire season so far. The wildfires exploded during the drought, in part because of the extremely dry conditions. So far this year, just over 476 square miles (1,234 square kilometers) have burned in California. That’s well below the five-year average of 2,031 square miles (5,260 square kilometers), according to the California Department of Forestry and Fire Protection.