The severe drought gripping nearly all of California eased ever so slightly this past week, but the state's reservoirs remain "seriously low," according to the latest figures released Thursday.
The amount of the state that now falls under the "severe" drought category — the third-harshest on a five-level scale — was down to 97.5%, a slight improvement from the 99.8% share during the same period last week, according to the U.S. Drought Map.
The progress, in part, is the result of above-normal rainfall in Southern California deserts for the last six months, according to Richard Tinker, who authored the latest drought report.
"Unfortunately, rainfall in this arid region will have no impact on the water shortages and seriously low reservoir stores reported throughout the state," he wrote.
Meanwhile, a study published in the journal Science on Thursday estimates that the ongoing drought in the western United States has caused a loss of 63 trillion gallons of groundwater since the beginning of 2013.
Researchers from UC San Diego's Scripps Institution of Oceanography and the U.S. Geological Survey said the figure is the equivalent of four inches of water across the United States west of the Rocky Mountains.
Water supplies in California's three largest reservoirs — Trinity Lake, Lake Oroville and Lake Shasta — are roughly at 30% capacity, close to the record lows reached in 1977.
The average capacity for most of the state's reservoirs, however, is at 59%, far better than the statewide average of 41% during the crippling drought of 1977, said Ted Thomas, spokesman for the California Department of Water Resources.
In July, the state's largest federal reservoir at Lake Shasta was at 36% capacity. But the latest numbers on Wednesday show the reservoir is only at 31% capacity, which is 4.5-million acre-feet of water.
Lake Oroville has also taken a huge hit during the prolonged drought.
At the reservoir's lowest point in September 1977, its capacity was at 645 feet above sea level, he said. As of Wednesday, the reservoir's capacity was at 684 feet above sea level.
Thomas said the low reservoir storage levels only stresses the need for conversation.
"The more we use, the less we have," Thomas said.