SAN DIEGO – With recent storm systems that swept through the west, California has seen more precipitation this year than normal, bringing the water supply stored in reservoirs — both locally and across the state — up from historic lows to levels that are some of the highest in years.

And with drought conditions having improved in much of California, experts say that the amount of water captured from this year’s particularly wet winter could help ease the impact of hotter, drier weather in San Diego, as the state recovers its depleted water supplies. 

“The state received nine atmospheric rivers and they provided major precipitation, (allowing) water agencies across the state – including San Diego County – to store some of that water for hotter, drier summertime, when water usage goes up,” Efren Lopez, water resources specialist with the San Diego Water Authority, said to

One of the state’s largest reservoirs, Lake Oroville in Butte County, was considered to be among the driest in the state last November when it reached about half of the 58% historical average capacity. Now, according to the Department of Water Resources (DWR), the reservoir is about 76% full, which is over 110% the historical average.

As of March 3, the snowpack in the Sierra Nevada – the state’s frozen reservoir – has far exceeded normal levels, as data from DWR shows that all three sections of the mountain range are around 140 to 200% of the historical average for April 1.

That trend holds true for local San Diego reservoirs.

A spokesperson for Sweetwater Authority – the agency that monitors two of the county’s reservoirs that are able to capture precipitation, Sweetwater and Loveland – said to that both of the reservoirs haven’t been this full in years. 

As of March 9, Sweetwater Reservoir was estimated to be at over 61% capacity, holding about 17,289 acre feet in water. Before the storm last week, the reservoir was about 56%, according to numbers collected on Feb. 20.

One acre foot is enough gallons of water to cover a football field about a foot deep. The current water levels in Sweetwater, according to the Sweetwater Authority, are enough for about a year’s supply of water.

These gains in reservoirs are expected to continue easing drought conditions across much of the state in the short term, however, experts say it will likely not be enough to fully recover given the climate pattern of longer, hotter periods and frequent dry winters. 

This pattern, as illustrated by the last few years’ lack of precipitation, can cripple the state’s water supply, worsening drought conditions in areas that rely on things like the snowpack and surface water capture. But San Diego’s hydrology is different.

Since the early 2000s, the county has taken extensive measures to diversify the water supply, in order to insulate residents from the impact of sustained droughts. 

Very little of the county’s water supply currently comes from local reservoirs that trap surface and groundwater, unlike other parts of the state like Northern California and Los Angeles.

“Our reservoirs are used as a storage system for our imported water and they also serve as emergency storage in case there is a drought or we get cut off from our supplies,” Lopez said.

The bulk of this imported water comes from the Colorado River via the Imperial Irrigation District. Another of the region’s major, and most expensive, water sources is the Carlsbad Desalination Plant, which produces about 50 million gallons of drinkable water every day from the ocean water.

Because of this diversification, abnormally wet or dry years have little impact on whether water will continue to flow. 

“It’s great to have these wet years because we can turn off our irrigation and conserve water that way and then we can use that water that’s conserved later in (summer) when it’s really hot,” Lopez said. 

These kinds of conservation efforts countywide have cut back per-person water use by nearly 40% since the 1990s, which has helped maintain the more drought-sensitive sources of San Diego’s water supply.

While both conservation and reliable water sources are generally regarded as good things, it has come at a cost for residents: higher rates given the sale of less water.

San Diego County has raised rates by an average of about 4% in each of the past five years to cover the costs associated with the agency’s annual fixed expenses for its diversified supply, as water use has fallen.

The recent storms could ease some of the financial burden from purchasing water from these more expensive sources.

Sweetwater Authority, in a statement in February, said that transfers of water captured from the recent precipitation between the reservoirs it administers could help save ratepayers in National City, Chula Vista and Bonita approximately $11 million in costs over the coming months.

Despite that short term relief, drought conditions remain a concern for experts in the region.

“We promote the value of each drop of water. We can use it efficiently, because we have it,” Lopez said. “But we have to accept that there’s a new reality with our climate, which (has) longer, hotter, drier spells…We need to be mindful (of) that.”