Saqib Rahim reports via Wired: It’s been one of the wettest years in California since records began. From October 2022 to March 2023, the state was blasted by 31 atmospheric rivers — colossal bands of water vapor that form above the Pacific and become firehoses when they reach the West Coast. What surprised climate scientists wasn’t the number of storms, but their strength and rat-a-tat frequency. The downpours shocked a water system that had just experienced the driest three years in recorded state history, causing floods, mass evacuations, and at least 22 deaths.
Swinging between wet and dry extremes is typical for California, but last winter’s rain, potentially intensified by climate change, was almost unmanageable. Add to that the arrival of El Nino, and more extreme weather looks likely for the state. This is going to make life very difficult for the dam operators tasked with capturing and controlling much of the state’s water. Like most of the world’s 58,700 large dams, those in California were built for yesterday’s more stable climate patterns. But as climate change taxes the world’s water systems — affecting rainfall, snowmelt, and evaporation — it’s getting tough to predict how much water gets to a dam, and when. Dams are increasingly either water-starved, unable to maintain supplies of power and water for their communities, or overwhelmed and forced to release more water than desired — risking flooding downstream.
But at one major dam in Northern California, operators have been demonstrating how to not just weather these erratic and intense storms, but capitalize on them. Management crews at New Bullards Bar, built in 1970, entered last winter armed with new forecasting tools that gave unprecedented insight into the size and strength of the coming storms — allowing them to strategize how to handle the rain. First, they let the rains refill their reservoir, a typical move after a long drought. Then, as more storms formed at sea, they made the tough choice to release some of this precious hoard through their hydropower turbines, confident that more rain was coming. “I felt a little nervous at first,” says John James, director of resource planning at Yuba Water Agency in northern California. Fresh showers soon validated the move. New Bullards Bar ended winter with plumped water supplies, a 150 percent boost in power generation, and a clean safety record. The strategy offers a glimpse of how better forecasting can allow hydropower to adapt to the climate age.