The ongoing record-breaking drought in the Southwest US is putting hydropower’s long-term viability as a domestic energy source into question. Hydropower, often promoted by the industry as low-carbon, doesn’t directly give off massive amounts of climate-damaging emissions, but reservoirs essential to hydro are a large source of methane emissions. Recently the EPA has been petitioned to start measuring these greenhouse gas emissions as they do emissions from other large-scale facilities. But, the construction of new plants is expensive and incurs high environmental costs -- damming rivers alters communities and destroys nature.

This summer, hydropower plants and their affiliated reservoir systems are under further pressure due to low levels due to lacking snowmelt and precipitation. A recent report from the US Energy Information Administration estimates that the drought could slice hydropower’s electricity generation in half. As Nick Schlag, a partner with the consulting group Energy and Environmental Economics Inc., put it to E&E News, "The premise behind hydropower being a reliable resource is that there’s water behind the dam. When water levels are so low that you can’t actually run water through the turbines, the reliability value has been jeopardized.”

Why This Matters

Utilities and grid operators for Arizona's Glen Canyon Dam say this summer’s energy needs are secured. But at Lake Powell, the country’s second-largest dam, low water levels have forced New Mexico, Arizona, and other states to decide between conserving water or having electricity.

Limited water resources and rising temperatures intersect across the energy grid. A heatwave during the drought, causing people to switch on the AC, could spike demand. As efforts to retire fossil fuel plants continue, the expectation for hydro to fill the gap in energy demand is looking less likely. Further straining the limited resource, coal and gas plants require billions of gallons of water for cooling.

The Real Cost of Hydropower

The US has nearly 100,000 dams, but an estimated 75 to 90% no longer serve any functional purpose. Instead of providing energy, they harm ecosystems and water quality. The reservoirs created by dammed rivers add nearly a billion tons of carbon dioxide equivalent into the air every year as submerged vegetation and trapped nutrients from upstream break down and bubble methane to the surface. Meanwhile getting rid of dams can lead to waterway restoration.

The Klamath Basin will soon be the site of the largest dam removal in US history. Over $450 million has been allocated to demolish four of the river’s five dams. The project is a collaboration between the federal government, California and Oregon state governments, universities, consultants, nonprofits, and indigenous tribes. The first removal begins in the fall of 2023.