FIRO: A Drop in the Bucket?
The Coyote Valley Dam, and by extension Lake Mendocino, just got a software update. Officials are celebrating the revised water control manual, touting its incorporation of Forecast-Informed Reservoir Operations (FIRO) principles. The headline figure? An additional 11,650 acre-feet of potential water storage. Sounds impressive, right? Let's dig into the numbers.
The core idea behind FIRO is smart: use weather forecasts, specifically those related to atmospheric rivers, to make better decisions about when to release or store water. The goal is to balance flood control with water conservation, a particularly tricky balancing act in drought-prone California. And, according to Sonoma Water Board Chair Lynda Hopkins, FIRO has already saved water – "equivalent to a second Lake Mendocino," she claims.
That's a bold statement, so let's unpack it. Lake Mendocino holds roughly 113,700 acre-feet at full capacity. Hopkins is essentially saying FIRO has saved over 100,000 acre-feet. But wait. The fact sheet also mentions that "over the past three years, FIRO has saved nearly 30,000 acre-feet of water in Lake Mendocino." That's a pretty significant discrepancy. Is Hopkins exaggerating for political effect, or is there another factor at play? (Perhaps she's including projected savings, not just realized ones).
This is where the story gets interesting. Lake Mendocino isn't exactly a self-contained system. It "depends on annual rainfall and diversions from the Potter Valley Project to fill." The Potter Valley Project, which diverts water from the Eel River, has been in decline for years, facing regulatory hurdles and aging infrastructure. So, while FIRO might be optimizing water storage, the actual amount of water available is heavily dependent on factors outside of FIRO's control. I've looked at hundreds of these water management reports, and this interplay between local optimization and external dependencies is a constant source of misleading claims.
The Illusion of Control
The politicians are lining up to take credit, of course. U.S. Representative Jared Huffman praised the update for advancing drought management, flood control, and fish habitat, emphasizing the shift to science-based operations. DWR Director Karla Nemeth stated Lake Mendocino is the first of many efforts across California to guide new reservoir operations across the state. But how much of this is genuine progress, and how much is simply good PR?
Consider this: Lake Mendocino serves approximately 650,000 people in Mendocino, Sonoma, and Marin counties. That 11,650 acre-feet of potential additional storage? That works out to about 0.018 acre-feet per person. An acre-foot is roughly 326,000 gallons. So, we're talking about ~6,000 gallons per person. That might sound like a lot, but spread out over a year, it's less than 17 gallons per person per day. A drop in the bucket, really. (And that's assuming the potential is actually realized.)
And this is the part of the report that I find genuinely puzzling: the reliance on the Atmospheric River Reconnaissance Program. They're using Air Force and NOAA "Hurricane Hunters" and a network of drifting buoys to collect data on atmospheric rivers. It's impressive, no doubt. But it also feels…expensive. What's the cost-benefit analysis here? How much does this program cost, and how does that cost compare to the actual water savings achieved through FIRO? The press releases are silent on this point. For more information on the implementation of this decision-making tool, see New forecast-informed decision-making tool implemented at Coyote Valley Dam and Lake Mendocino - Scripps Institution of Oceanography.
A False Sense of Security
Ultimately, while FIRO and the updated water control manual represent a step in the right direction, they shouldn't be mistaken for a silver bullet. The fundamental problem remains: California faces a structural water deficit, exacerbated by climate change and increasing demand. Tweaking reservoir operations can only go so far. Until we address the bigger picture – including diversifying water sources, investing in infrastructure, and managing demand – we're just rearranging deck chairs on the Titanic.
