by Robin Meadows
In 1990, Gary Estes moved to Auburn, a town of nearly 14,000 in the Sierra Nevada foothills on the North Fork of the American River. Estes, an environmentalist, immediately joined the fight against Auburn Dam. The proposed dam site was only about one mile from his house.
The U.S. Army Corps of Engineers wanted to build Auburn Dam to boost flood control in the city of Sacramento, which is about 30 miles downstream of Auburn and which the Corps considers to be the region most at-risk for catastrophic flooding nationwide. But the American River already had the 340-foot high Folsom Dam between Auburn and Sacramento.
“The environmental community said, ‘Do we really need another dam?’” Estes recalls.
He and other Auburn Dam opponents thought there had to be a better way to protect Sacramento from floods―and they turned out to be right.
Estes’ search for alternatives to Auburn Dam sparked a new way to operate reservoirs for flood control. His quest also resulted in the California Extreme Precipitation Symposium, an influential conference that celebrated its 30th anniversary in July 2024.
A REVOLUTION IN RESERVOIR MANAGEMENT
Folsom Lake, like many reservoirs in California, is operated for both water storage and flood control. The latter entails releasing water to make room for stormwater, and releases were originally made according to a schedule based on historical weather. Today, water is released from Folsom Lake when storms are known to be on the way. This new approach is called forecast-informed reservoir operation or FIRO.
The idea to try FIRO at Folsom Dam grew out of collaboration between Estes and Don Baker, a fellow Auburn Dam opponent with a degree in meteorology. Baker had noticed a weather pattern over the Pacific Ocean that preceded flood events. One element of the pattern was a southerly jet stream that brought warm, moist tropical air from Hawaii to California, causing heavy rain.
“He thought that when you saw that pattern, you could release water from the reservoir,” Estes says.
Meteorologists now know that the weather patterns that had caught Baker’s eye are atmospheric rivers, storms that bring much of the rain and snow and cause most of the flooding in the Western U.S. But this had yet to be established in the early 1990s, when Baker first told Estes about the weather pattern that preceded inundation.
“We asked, “What should we do with this science?’” Estes says.
Estes suggested a symposium on predicting torrential rainfall, which was first held in 1994 and grew into the California Extreme Precipitation Symposium (CEPSYM). The observation of the flood-linked weather pattern also led to piloting FIRO at Folsom Dam.
“It was only because Auburn Dam was defeated that Sacramento interests realized they had to come up with Plan B,” Estes says.
FOLSOM DAM: FIRST DEMONSTRATION OF FIRO
In 1999, a key ally decided to try FIRO at Folsom Dam. Tim Washburn, then-general counsel for the Sacramento Area Flood Control Agency, convinced then-Congressman Robert Matsui to put FIRO-related language in a bill. Specifically, the language directed the U.S. Army Corps of Engineers to evaluate whether FIRO would work if a second, lower spillway was added to Folsom Dam.
The answer was yes. The first spillway is so high up the dam that Folsom Lake had to be roughly half full before releases could be made. The second spillway is significantly lower. “The huge benefit is we can pre-release ahead of floods,” says Carissa Abraham, an engineer at MBK Engineers and part of a team that updated the Corps operations manual for Folsom Dam. She presented their work at CEPSYM last summer, which focused on Anticipating and Planning for California Floods.
“With FIRO, we’re getting close to the flood protection Auburn Dam would have provided,” Abraham says. “It’s a testament to Gary Estes’s vision.”
Abraham describes implementing FIRO as a “tug of war with flood control on one side and everyone else on the other side.” She grew up boating with friends on Folsom Lake in the summer, and now gets a lot of questions from locals about why the lake is or isn’t full. Her answer is that the reservoir is multipurpose―providing drinking water, flood control, environmental flows, and recreation―and that “we’re trying to balance all that.”
Atmospheric river expert Marty Ralph also spoke at CEPSYM last summer, delivering a keynote address that included acknowledging FIRO at Folsom Dam as helping to pave the way for FIRO in Lake Mendocino and elsewhere. “Breaking ground on incorporation of forecasts into Folsom operations helped give us confidence in the Mendocino study,” said Ralph. As founding director of the Center for Western Weather and Water Extremes (CW3E), he has helped usher in a new era of FIRO in California.
BRINGING TOGETHER THE FLOOD CONTROL WORLD
Ralph first spoke at CEPSYM in 1999. “I thought, ‘Oh my gosh, here’s a meeting on exactly what I’m working on,” he recalls. He credits the symposium with facilitating integration of the emerging science of atmospheric river forecasting with flood management. Crucially, the symposium created a forum for extreme precipitation researchers to connect with water engineers and flood managers.
“CEPSYM brought together an audience uniquely receptive to hearing about the new ideas of atmospheric rivers and flooding,” Ralph says.
Estes attributes CEPSYM’s big-tent approach to his generalist background. He was originally drawn to engineering but didn’t have a specialized degree that might have narrowed his focus. His political science degree provided a broader perspective.
To mark CEPSYM’s 30th anniversary, Estes received an engraved rain gauge and a special recognition award for “extraordinary dedication to advancing the science and engineering of managing extreme precipitation in a way that has profoundly affected public policy.” Estes is now stepping down and George Booth, director of the Floodplain Management Association, pledges to continue sponsoring CEPSYM.
Estes thanks his wife, whose job at Hewlett-Packard supported them, for giving him the time and space to pursue his passions. “I told her years ago that my goal in life is to make a difference,” he says. “She called me her ‘house spouse’ and said that as long as I took care of her and the house, I was free to volunteer for good causes.”
“How do you spend your time?” Estes muses. “I try to make the world a little better.”
