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Historic snowmelt could resurrect 'ghost lake' for as long as two years

By Adriana Navarro, Accuweather.com
Fierce winds and an atmospheric river has battered California. File Photo by Terry Schmitt/UPI
Fierce winds and an atmospheric river has battered California. File Photo by Terry Schmitt/UPI | License Photo

After the latest atmospheric river event contributed to the resurrection of a "ghost lake," flooding nearby towns, residents in the path of snowmelt from the Sierra Nevada are waiting for the other shoe to drop.

The train of storms that slammed the West Coast over the winter into March filled parched reservoirs and revived the depleted snowpack. However, while the surplus of water provided an oasis amid a historic megadrought, snowmelt from the Sierra Nevada could contribute to more long-lasting concerns for flood-prone towns.

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Experts have pointed to the southern Sierra Nevada snowpack, which drains into the San Joaquin Valley, as a particular area of concern. Gauges have started to show some runoff, but it's just the start of what will likely play out as intense spring flooding, Jeffrey Mount, a senior fellow at the Water Policy Center at the Public Policy Institute of California, told AccuWeather national reporter Bill Wadell.

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The snowpack held 317 of its historical average as of April 12, and local authorities have warned they have only a short amount of time to prepare for a spring runoff from years' worth of snowmelt delivered over the course of only a few months.

"In the southern Sierra, you're looking at about three years' worth of total runoff [that] is now frozen in place up there in those mountains, and it's going to come down into a system which is absolutely not designed to handle it," Mount said.

One of those areas is the Tulare Basin in the southern San Joaquin Valley, an area that has no outlet to the ocean. Instead, the water travels to what was once Tulare Lake -- where now small towns and farmland occupy the drained lakebed.

The agricultural town of Allensworth, which has a history of periodic flooding, is among those at risk from the impending snowmelt.

Founded in 1908, Allensworth was California's first town established by African Americans, though its population is now predominantly Hispanic. As its population fluctuated over the years, now home to nearly 600 people, it has frequently been referred to as "the town that refuses to die."

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However, the same holds true for the drained watershed it was built upon.

Locals refer to Lake Tulare as a "ghost lake," as water levels at the drained lake will occasionally refill during particularly wet years. However, before the area was developed for agriculture and the rest diverted for irrigation, it was once the largest freshwater lake in the western United States, fed by snowmelt from the Sierra Nevada.

Years of heavy rainfall and snowmelt call forth the ghost of the lake, however, haunting the residents with damaging floodwaters. This happened in 1983 and 1997 -- both years that experienced very strong El Niño events.

Residents prepare for this specter not with salt and crucifixes but with sand and heavy machinery.

When the water returned once more in mid-March, Jose "Chepo" Gonzales, 50, worked to mitigate the reach of the flooding as his father had before him nearly 45 years earlier in 1979.

"I got to do like my dad did then," Gonzales told the Los Angeles Times as he moved sand with a small tractor to help build a berm. He added that the repairs his father had made to stop a leak in the canal bank were still visible.

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Roughly 20 miles to the northwest, the city of Corcoran has all eyes on the levee that stands between the revived Lake Tulare and the city's streets.

"The primary concern right now is that water level is at 178 feet. We have a levee that's 188 feet," Corcoran City Manager Greg Gatzka told Wadell. "We know more water is coming. If that water is going to get too high on top of this levee, we have the situation where that levee can start deteriorating and get compromised, which is our biggest concern and biggest fear."

Kings County, where Corcoran is located, declared an emergency on March 10 and activated its emergency operations center on March 21. While President Joe Biden signed an emergency declaration on April 3 that made federal funding immediately available for seven counties, including Tulare and Kern, Kings County was not included.

Kings County Board of Supervisors Chairman Richard Valle said in early April that this was because the county did not submit its loss damages to the state on time.

"I'm told that once the state could reaffirm our loss damages, then it should not be an issue for us, Kings County, to get added to that declaration," Valle told the Fresno Bee.

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The damages would largely impact agriculture. In 2021, the county's crops were valued at $2.3 billion, and it's estimated that flooding could ruin more than 41 of the crops plus cost $1 billion in damages.

About 30 square miles of farmland had been inundated by the revived lake by early April. Kings County Sheriff Dave Robinson told the Fresno Bee that people had been showing up with boats and kayaks, mistaking the area as a recreational waterway.

"The lake bottom is private farmland that is flooding. Over the course of the next few months, we will be dealing with this," Robinson said during a March press conference.

The damage will not be isolated to just Allensworth and Corcoran, however, with many other rural communities looking to shore up their levees.

"There are a number of small rural communities along the San Joaquin River that are nervous, and they should be nervous because they're going to have to let a lot of water go down that river and it's not well-designed as a flood control structure," Mount said.

Local authorities and water experts have warned that the pending flood event has echoes of 1983, a year when record-level snowpack levels had resulted in Lake Tulare holding floodwaters for two years.

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The scenario towns around Lake Tulare are likely to see is similar to the year 1983, Mount said, which was a strong El Niño year that also saw high snowpack levels. Over the course of two months, about 80% of the snowpack had melted and either turned into runoff or evaporated. Roughly 100,000 acres were under some 3 million acre-feet of water, submerging portions of towns like Allensworth and Corcoran.

The area had pumped water into canals and sent some to Southern California but relied heavily on evaporation, Mount said. The result was water sticking around for two years.

"I don't see any way around it," Mount said. "We're probably going to see the same thing this year where we're looking at two years of water."

Should 2023 echo 1983 and face two years of Lake Tulare lapping at the city's border, Gatzka warned the city would also need to weather a long recovery period with the resulting economic impact.

Ironically, the unusually low March temperatures are one of the factors behind why the flooding could be so intense.

The stubborn cold kept the snowpack from melting for a longer period of time, allowing for more snow to build up in the mountains. When warmer weather arrives, all that snow will melt, and the runoff is more intense.

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March temperatures in 1983 fell 2-4 degrees below normal in some locations of the Sierra Nevada with precipitation at least double the usual amount, according to AccuWeather senior meteorologist Tom Kines. This year, temperatures averaged about 4 degrees below normal in the mountains and foothills east of the San Joaquin Valley, and precipitation was well above normal in both the mountains and the valley.

"Roughly 80% of that snow is likely to melt and turn into runoff or go back into the atmosphere in that two-month period of May and June," Mount said. "And that's kind of what happens even in our really, really epic years, like 1983. That's precisely what happened."

Even with the relief from the drought, Mount cautioned against assuming the state's troubles with persistent dry weather were over.

"How quickly we forget that just a year ago we were in a screaming drought, and how quickly we forgot that in 2019 we had a very wet year," Mount said. "We filled all our reservoirs, and one year later, we were in trouble."

That year had started off with nearly 8% of the state free of drought and abnormally dry conditions, but by early March, that percentage had soared to 93%, according to the U.S. Drought Monitor. The percentage remained between 80% and 96% until November, when dry weather swept across the state, plummeting the percentage of the state that was free of dry and drought conditions to 18.6%.

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While that percentage continued to fluctuate, even rising again to 96% at the start of 2020, it quickly dropped once more at the end of January 2020 and continued to fall. From Dec. 8, 2020, to Feb. 21, 2023, the percentage of California free of drought conditions remained under 1%.

"We fall back into drought very quickly, so no, this has not solved all our problems," Mount cautioned. "In fact, you never solve a problem in California water, you just manage it."

While the rainfall has significantly boosted water levels at California reservoirs, Mount pointed out that the state relies heavily on groundwater. In an average year, he said, it makes up a third of the state's water supply or two-thirds in a drought year. One wet year alone won't be enough to restore those aquifers.

"If you're a fish, you need more than one good wet year to recover. And if you're a bird, you also need more than one good wet year to recover," Mount said. "So drought is in the eye of the beholder, but all I can tell you is our reservoirs are full. We are relaxing our drought restrictions appropriately at this point, but we have not solved the problem."

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