The federal government is planning to release as little as 6 million acre-feet of water from Lake Powell this year — a historic low.

Officials say the move is necessary, after an abysmally dry winter, to keep plummeting lake levels above 3,490 feet of elevation, the point where water is too low to flow through the turbines that generate hydropower.

But doing so could create another hydropower mess downstream at Lake Mead — especially impacting the Arizona farmers and ranchers that rely on this electricity to pump and move water.

The modified releases could drop Lake Mead’s water levels below 1,035 feet of elevation by fall. And that could force 12 of the dam’s 17 turbines offline.

“We’re basically knocking out most of Hoover’s generating capacity,” said Jordy Fuentes, executive director of the Arizona Power Authority that oversees the state’s share of this power. “When that happens, the resource becomes unaffordable for most of our customers.”

Less water at Mead could damage turbines

When water levels at Lake Powell fall below 3,490 feet — a point called “minimum power pool” — the only way to move millions of acre-feet of water downstream is to pass it through four smaller river outlet tubes.

Those tubes were never designed to handle that much water, and the federal Bureau of Reclamation is worried that regular use could cause cavitation, when tiny air bubbles in water expand and then collapse, releasing energy that can severely damage pipes.

Instead of redesigning the dam to flow water at lower lake levels — which could cost upwards of $3 billion — Reclamation has chosen for now to keep Lake Powell above 3,490 feet.

It was long thought that Lake Mead, which has a different dam design than Powell, had more of a hydropower buffer than its upstream counterpart.

Mead doesn’t reach its own minimum power pool until 950 feet of elevation. The lake is now 100 feet above that line.

But concerns emerged last year that cavitation could still damage most of Mead’s turbines at a much higher 1,035 feet — a level it could reach in a matter of months.

Reclamation plans to shut down the older turbines that aren’t designed to handle these lower water levels, Fuentes said, instead of risking damage.

Less power could raise energy prices

Discussions are ongoing to replace the turbines, though it’s unclear who should pay for them or how long the replacements might stave off cavitation problems if water levels continue to plummet.

It also could take years to fully replace the turbines and restore diminished generating capacity — which still may not be enough to keep pace with increasing energy demands.

Uncertain water cuts after 2026, when the current rules governing the lakes expire, further complicate long-term planning for the 71 Arizona cities, tribes, electrical co-ops and irrigation districts that receive power from Hoover Dam.

“The way our contract is set up, we pay the same amount, whether we get our contracted energy or not,” said Robert Van Hofwegen, a dairy farmer and district manager of Electrical District 8, which delivers power in western Maricopa County and eastern Yuma County.

Paring back production makes each unit of power more expensive and less competitive with other energy options.

It also represents the loss of a clean, renewable power source, one that can ramp up quickly and efficiently during times of high energy use.

This reliability is crucial because it helps stabilize the western power grid, Salt River Project noted in a statement.

Farmers are already facing slim margins

Though the utility is among the largest Arizona users of Hoover’s hydropower, it amounts to less than 1% of the electricity that it delivers to homes, businesses and farms in metro Phoenix.

SRP has other sources to fill the gap.

But Fuentes said smaller, rural providers with less diverse portfolios may be forced to buy electricity on the open market at the last minute, and likely at higher cost.

All of which could have disproportionate impacts on farmers and ranchers who already are operating on razor-thin margins.

At the Paloma Irrigation and Drainage District, which Van Hofwegen also manages, about 40% of the power the district needs to pump and distribute groundwater originates at Hoover Dam.

“Power prices will go up, so we’ll probably have to raise water prices,” he said. “It’s just one more Jenga block on top of the tower, and it’s getting pretty teetery up there for a lot of farmers.”


Joanna Allhands writes about issues important to the Arizona Farm Bureau. Reach her at joannaallhands@azfb.org.