Hydropower decline adds strain to power grids in drought

ST. LOUIS (AP) — After water levels at a California dam fell to historic lows this summer, the main hydropower plant it feeds was shut down. At the Hoover Dam in Nevada — one of the country’s biggest hydropower generators — production is down by 25%. If extreme drought persists, federal officials say a dam in Arizona could stop producing electricity in coming years.

Severe drought across the West drained reservoirs this year, slashing hydropower production and further stressing the region’s power grids. And as extreme weather becomes more common with climate change, grid operators are adapting to swings in hydropower generation.

“The challenge is finding the right resource, or mix of resources, that can provide the same energy and power outputs as hydro,” said Lindsay Buckley, a spokesperson for the California Energy Commission.

U.S. hydropower generation is expected to decline 14% this year compared with 2020, according to a recent federal forecast. The projected drops are concentrated in Western states that rely more heavily on hydropower, with California’s production expected to fall by nearly half.

The reductions complicate grid operations since hydropower is a relatively flexible renewable energy source that can be easily turned up or down, experts say, such as in the evenings when the sun goes down and solar energy generation drops.

“Hydro is a big part of the plan for making the whole system work together,” said Severin Borenstein, a renewable energy expert at the University of California, Berkeley and board member of the California Independent System Operator, which manages the state’s electric grid.

Borenstein noted that hydropower is important as the state works to build out its electricity storage options, including by installing batteries that can...