Hydropower has no direct substitute.

It doesn’t emit the greenhouse gases of coal or natural gas.

It’s available any time, unlike solar and wind, to meet spikes in demand.

And it’s cheap. 

But the outlook for hydropower — a source that fills up to half of some Arizona irrigation and electrical districts’ power needs — is growing increasingly grim.

Lake Powell could be too low to generate any electricity in more than half the years through 2060.

And Lake Mead’s capacity could fall to a third of what it is now by spring. It’s forecast to remain there most of the time through 2039.

Hydropower costs could skyrocket

Water levels are plummeting at the nation’s two largest reservoirs, and that is making hydropower more expensive to generate.

If production falls too much, it could quickly become among the most expensive forms of energy, potentially forcing buyers to walk away from their long-term contracts.

That’s a problem for federal officials, which rely on hydropower revenue to operate and maintain the lakes.

And it’s a problem for farmers, which depend on affordable power to pump and deliver water for irrigation.

“This is an emergency,” said Dennis Delaney, general manager at Southwest Public Power Agency, which helps find and manage power for irrigation and electrical districts.

“We can replace lost energy, no problem, but replacing the lost capacity that hydropower provides is the challenge. The whole region is scrambling to add capacity.”

Without sufficient capacity — the ability to store and distribute power at a moment’s notice when demand spikes — systems can become overloaded, unable to supply electricity when it’s most needed.

Small districts are joining forces

Replacing lost capacity won’t be cheap or easy, particularly as hydropower diminishes and as intensifying heat and proliferating technology increase demand.

And that is only going to make electricity more expensive.

Few irrigation or electrical districts have the resources to bolster capacity on their own.

But many are banding together to build facilities that can.

About 50 entities have joined a large-scale solar and battery storage project in Eloy that could be online by December 2027. 

The 400-megawatt solar and 400-megawatt battery project now in the final stages of approval can generate and store energy for when it’s needed.

It also would be connected to the Western Area Power Administration’s distribution network — which already moves electricity generated by hydropower — to help replace some of Lake Mead’s lost energy capacity.

“It’s not going to solve everything,” said Patrick Ledger, CEO of Arizona Generation and Transmission Cooperatives, which is shepherding the Eloy project for its members.

“But it’s a really good first step to provide a little bit of safe harbor, some flexibility and resource diversity for customers.”

Many are turning to batteries

Electrical District 3 — which serves residents in Maricopa and Stanfield, as well as providing power to irrigate about 65,000 acres — only gets about 7% of its electricity from hydropower. 

But demand for power is growing quickly as growth in Maricopa accelerates. 

The district has made substantial investments in natural gas, solar and battery storage since 2020.

It is banking on the Eloy project to help fill expected hydropower losses at Lake Mead. 

“At a time when demand is rising, this sharp reduction (in hydropower) creates risk and uncertainty for electric cooperatives and not-for-profit electrical districts across Arizona,” general manager Brian Yerges wrote in a letter of support for the project.

Many other districts wrote similar letters, noting the need for additional projects that can provide long-term capacity — including solar and battery storage or natural gas peaker plants that only turn on when demand spikes.

What about Lake Mead?

Though this is critical work for the long term, challenges remain in the short term.

The federal Bureau of Reclamation has no real plans to replace lost power at Lake Powell.

And while plans are taking shape at Lake Mead to replace a handful of turbines that can operate at lower water levels, they are unlikely to be in place before the Eloy project or others become operational.

Even if all 17 turbines are replaced, it’s unclear how much time that buys before water levels at Lake Mead are too low to generate any hydropower. 

These shakeups could force districts to buy expensive backup sources on the open market.

Many are combining their purchasing power ahead of time in hopes of getting a better deal.

Meanwhile, officials are exploring whether it makes sense to install batteries at Lake Mead to store hydropower, excess solar power or any other available electricity.

“Solar is sometimes so abundant that generators will pay you to take it,” said Jordy Fuentes, executive director of Arizona Power Authority, which manages Arizona’s share of hydropower from Lake Mead. 

“Imagine turning a low-capacity resource like that into one that has the capacity utilities need. We could make the system a lot more efficient if we invested in these things.”


Joanna Allhands writes about water, land use and other issues important to the Arizona Farm Bureau. Reach her at joannaallhands@azfb.org.