'Deep Trouble': Water Levels at California's Reservoirs Leaving Towns Dry

Parts of California could be in "deep trouble" in the coming years if more reservoirs are not built to meet the demand for water, with some towns already suffering from major shortages as a result of the megadrought that has gripped the state for decades.

Record rainfall has hit the state since the end of December, which has pulled most of California out of extreme drought.

However, despite increased water levels in many of California's major reservoirs, a lot more rainfall is needed to completely replenish not only the surface reservoirs but the groundwater stores as well.

If the water stores cannot be refilled, many towns may suffer from shortages.

"It really depends on where in California you're talking about in terms of trouble. Certainly, some smaller communities are already in deep trouble," Jacob Petersen-Perlman, a water resources geography expert and assistant professor at East Carolina University in Greenville, North Carolina, told Newsweek. "A couple of Northern California communities ran out of water to supply citizens this fall.

"Other wells are going dry in the Central Valley. Farming is also another dimension where some growers are facing very difficult times, with dropping groundwater levels and not enough water to satisfy their water rights."

Lack of water is already impacting parts of the state. Coalinga in Northern California was forecast to run out of water by the end of last year, with city officials having to purchase additional supplies at a huge cost.

"Our community can't rely just on precipitation amounts or atmospheric moisture demand alone to understand how severe a drought is," Daniella Rempe, a hydrologist and geomorphologist at the Jackson School of Geosciences, University of Texas in Austin, told Newsweek.

"We have to look underground to see how much water has been depleted from storage belowground in soils and rock. This is where the water that supplies streams and trees during [California's] long dry season comes from."

Rempe previously told Newsweek that long periods of low rainfall also remove moisture from plants, increasing the risk of fires. Groundwater levels are also impacted.

"This groundwater is absolutely crucial to supplying streams in [California's] long, dry summers every year, not just during drought," she said. "But what happens during drought is that the rains that would refill this groundwater end up just refilling the dry root zone and either delaying or preventing recharging of the groundwater system that supplies streams and reservoirs."

While the start of 2023 has been a wet one, the rest of the year may not see the same degree of rain for months, putting the reservoirs and groundwater levels at risk of drying out again.

To prepare for the absence of rain, pressure is building for California officials to build more reservoirs to help provide water to residents.

"Nearly every major river in California is dammed, and most were built between the 1920-1980 era," Rich Pauloo, a hydrogeologist and co-founder of the Water Data Lab, told Newsweek.

"We're living off those former investments and massive public works projects, and there's not much more capacity we can squeeze out of California's rivers. We need to turn our water management system 'upside down' and use the natural storage capacity of our state's subsurface aquifers.

"For scale, all of our surface reservoirs are around 50 MAF [million acre-feet], and hydrogeologists estimate the capacity of our subsurface reservoirs [aquifers] at 850 MAF to 1,300 MAF. Thus, aquifers are 17 to 26 times larger 'buckets' than our surface reservoirs, and we would be wise to start refilling them."

Pauloo said that intentionally refilling these natural, underground reservoirs via managed aquifer recharge would bolster the water supply during the dry periods expected in California, especially as climate change continues to intensify droughts and floods.

"It will also increase groundwater levels and help prevent wells from going dry, especially the typically shallow wells associated with disadvantaged communities most vulnerable to drying out during drought. It will support healthy flows in interconnected surface waters [streams and rivers] for recreation and fish. And it will supply groundwater-dependent ecosystems with the water they need," Pauloo said.

One reservoir being planned is the Sites Reservoir in the Sacramento Valley in Northern California, which will create 1.5 MAF of off-stream water storage. Construction of the reservoir is expected to begin in mid-2024, and it is set to be operational by 2030. There are also proposals for desalination plants to help augment the water supply using salt water.

"Also, it's not necessarily supply-side solutions that will solve everything. Regulations and behavioral changes in water use could significantly improve conditions in California," Petersen-Perlman said.

"I think it's safe to say that the larger cities won't run out of water any time soon. It's too politically costly for state regulators to let that happen. Since most of California's and the world's water use is agricultural, farmers will most likely be the first ones to be affected by cuts on a grand scale," he said.

Update 01/17/2023 9.37 a.m. ET: This story has been updated to include additional context.

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