Federal water managers will repair a set of little-used pipes within Glen Canyon Dam after discovering damage earlier this year. The tubes, called river outlet works, have been a focus for Colorado River watchers in recent years. If Lake Powell falls much lower, they could be the only way to pass water from the nation’s second-largest reservoir to the 25 million people downstream of the dam.

The Bureau of Reclamation will use $8.9 million from the Bipartisan Infrastructure Law to apply a new lining to all four pipes, which were originally coated more than 60 years ago. Conservation groups, however, say Reclamation should turn its attention and finances to bigger, longer-term fixes for the dam.

“Duct tape and baling wire won’t work in the long run,” said Kyle Roerink, executive director of the nonprofit Great Basin Water Network. “These short-term efforts are myopic in the grand scheme of things.”

The river outlet works were originally designed to release excess water when the reservoir nears full capacity. Now, Lake Powell is facing a different problem: critically low water levels.

After more than two decades of climate-change-fueled drought and steady demand, the reservoir is less than 40% full. It was only 22% full as recently as 2023.

Currently, water passes through hydroelectric generators inside Glen Canyon Dam before flowing into the Colorado River. Water experts fear that shrinking supplies and unsustainably heavy demand will keep sapping Lake Powell, bringing the top of the reservoir below the intakes for the generators.

Not only would such a drop jeopardize power generation for about 5 million people across seven states, but it would leave the river outlet works as the only means of passing water from Lake Powell to the other side of the dam.

The pipes are only capable of carrying a relatively small amount of water. If they become the only means of passing water through the dam, the Colorado River’s Upper Basin states—Colorado, Wyoming, New Mexico, and Utah—could fail to meet a longstanding legal obligation to share a certain amount of water with their downstream neighbors each year.

That could mean less water for cities like Las Vegas, Phoenix and Los Angeles, as well as massive farm districts that put vegetables in grocery stores across the country.

Recent boosts in Lake Powell water levels are mostly due to back-to-back snowy winters, which climate experts say are becoming increasingly rare.

Conservation groups are putting pressure on policymakers to rein in demand. Some environmental advocates are asking them to consider draining Lake Powell altogether and storing its water elsewhere.

“We need to start planning for a river with less water,” said Eric Balken, executive director of the nonprofit Glen Canyon Institute. “That means drastically rethinking infrastructure that was built for a much bigger river. As climate change and overuse continue to put pressure on this river system, Glen Canyon Dam’s plumbing limitations will become more and more problematic.”

This story is part of ongoing coverage of the Colorado River, produced by KUNC and supported by the Walton Family Foundation. KUNC is solely responsible for its editorial coverage.