(KTXL) — The people in charge of California reservoirs have to find the proper balance between holding more water because of a drought and releasing water due to incoming storms, but a burgeoning Air Force weather program is helping reservoir operators find that balance.
Ever since the Folsom Dam was completed in 1955 and the Coyote Valley Dam in 1958, the question of how to gauge when to release water from the respective Folsom Lake and Lake Mendocino has been top of mind for state water engineers.
With weather forecasts being relatively unreliable compared to what is available today, the decision was made to keep the water level at these and other reservoirs at 60 percent of capacity during the winter and to release water as more rain and snowfall occurred.
“Back when the dams were built, it was a pretty wise choice in my opinion not to use weather forecasts because they weren’t very good,” Marty Ralph, director of the Center for Western Weather and Water Extremes at UC San Diego’s Scripps Institution of Oceanography told NPR.
“But now with satellites and radars and models and science, there’s been a lot of improvements, so it seems sensible to give it a try.”
One of the newest tools to aid in forecasting the weather, like the recent atmospheric rivers, is the Atmospheric River Reconnaissance program and its United States Air Force Reserve Weather Reconnaissance Squadron, more commonly known as the “Hurricane Hunters.”
The program began in November 2022, in partnership with the National Oceanic and Atmospheric Administration following a bomb cyclone in October of the previous year that caused mass flooding in Washington State.
The mission of the Hurricane Hunters is to fly their WC-130J, a weather reconnaissance plane based on the C-130J transport plane, into tropical disturbances, storms, hurricanes and other winter storms to obtain data.
The data gained from these flights is helping make the decisions at the Folsom Dam and Coyote Valley Dam, and in the future could help inform the engineers at other reservoirs.
On January 11, a team from FOX 40 News flew for more than 10 hours with the Hurricane Hunters to get an up-close look at them in action.
To collect data from these unique weather patterns, the team drops 16-inch long and three-inch round instruments from the airplanes that measure temperature, pressure, water vapor and winds, and send this back to a “central repository.”
“The AR Recon program also will begin working more closely with Forecast-Informed Reservoir Operations (FIRO), a multi-agency effort to manage water levels in California reservoirs most efficiently,” the Scripps Institution of Oceanography wrote in a December 2022 article about the program.
Folsom Reservoir has benefited from this new and more accurate forecasting by allowing the lake to increase winter storage capacity by 20 percent, to 80, and make more effective decisions to release water when an incoming atmospheric river forms off of the California coast.
Once a strong weather system is detected, the reservoir and dam operators can begin releasing water three to five days ahead of the storm, rather than staying more empty from the start of the winter season, the time when California receives the majority of its rain and snowfall.
This tighter time period allows water levels to remain at a safe level for the dam during the winter and ensures that more water is held for longer periods of time after the storms stop.
Since 2012, California has been through two drought periods, the second of which continues in spite of a series of back-to-back storms in December and January.
The storms will certainly stop one day and state water engineers are getting a better understanding of how to manage the water levels for when that day comes, but they’re also aware that Mother Nature can be unpredictable.
“They’re constantly rerunning these ensemble forecasts for river flows,” Drew Lessard, Folsom Lake Manager at the state Bureau of Reclamation told NPR. “It’s working as intended, but it’s certainly pretty dynamic.”