By the time Colorado River water reaches Phoenix, it's already been on a long journey.
Before it comes out of your kitchen faucet, water flows through hundreds of miles of canals, rivers and streams. Before that, more than two thirds of the river begins as water in the Rocky Mountains. Now, the agency that brings Colorado River water to the Phoenix and Tucson areas is stepping away from a program to boost that snow.
The Central Arizona Project, or CAP, operates a 336-mile-long canal system that carries water from the Colorado River, across the desert, and into the Phoenix and Tucson areas. Since 2007, it has been part of a collaborative effort to run cloud seeding equipment in Colorado, Utah and Wyoming.
In a close vote at its latest board meeting, the agency chose not to renew funding for the program's next chapter.
Cloud seeding is a technology that can help boost snow totals in the mountains where the Colorado River begins. It is done by releasing particles into the air that cannot make new snow, but can essentially tell clouds where to drop their moisture.
The program has brought together water users that benefit from faraway snowmelt — like CAP, water agencies in Las Vegas and Los Angeles and major farming districts in Southern California — and agencies that manage water near the snowy mountains themselves.
In recent years, water agencies in Arizona, California and Nevada have sent about $1.5 million per year to upstream cloud seeding work. Going forward, each agency's funding for cloud seeding work would be capped at $525,000 per year in 2027 and gradually climb to $750,000 per year in 2036.
CAP board members questioned whether Colorado River users in Arizona would be getting their money's worth.
"It's hard to see how this is really going to help our customers, especially in the environment that we're working in right now, and our taxpayers," said Alexandra Arboleda, a CAP board member who voted against renewing funding for the program.
Some board members expressed concern over the efficacy of cloud seeding. Scientific studies of the technology have proven that it can add snow in mountain areas, but research is limited on exactly how much.
"The science says it works, but the outcome is difficult to really measure at the end of the day" said Stephen Miller, a CAP board member who voted against renewing funding for the program. "That's where the skepticism comes in."
Scientists and technicians who implement cloud seeding in the Rocky Mountains are confident that it can meaningfully bring snow to places it is needed, and CAP experts made that case to board members.
Nolie Templeton, CAP's Colorado River policy and analysis manager, pointed to studies that suggest up to 20% boosts to snowpack.
"Everyone benefits from a healthier Colorado River basin system," she said. "When we start to look at some of those zero to 20% above baseline precipitations, this quickly becomes one of the most cost-effective strategies to add more water into the basin."
The decision to step back from the collaborative program comes in the middle of an intense feud between two groups of states that use the Colorado River. The Lower Basin states of Arizona, California and Nevada have been locked in disagreement about how to share the shrinking water supply with their Upper Basin counterparts — Colorado, New Mexico, Utah and Wyoming.
At a CAP meeting in early October, board members questioned whether the agency should keep putting money toward a program that might help upstream rivals. Some of those same concerns were brought up at the early-November meeting that resulted in CAP's decision to step away from the program.
"If it does produce an extra 10% per storm that's cloud-seeded, I think that's definitely a worthwhile effort," said April Tornquist, a CAP board member who voted to renew funding for the program. "My biggest concern is just how will we be treated by the Upper Basin? Will we get to see any of that extra 10%?"
Negotiators from the rival basins spent years in tense talks and ended at an impasse, forcing the federal government to come up with a plan to keep the river working somewhat normally after states couldn't agree on a strategy to do the same.
The federal plan forces mandatory cutbacks on the Lower Basin, but does not require the Upper Basin to make any new mandatory cutbacks to water demand. That has only turned up the heat on tensions between the two. The state of Arizona and the Central Arizona Project both moved to join a lawsuit against the federal government over that plan. In doing so, they appear to be tiptoeing closer to a potential Supreme Court battle between the two basins.
However, Arizona's allies in the Lower Basin have already moved to fund more Upper Basin cloud seeding work in the future. Both the Southern Nevada Water Authority and a group of six California water agencies sent letters to CAP encouraging its board to keep funding cloud seeding in the Rockies.
Proponents of cloud seeding are candid that it won't solve the massive regionwide water supply shortage, but have described cloud seeding as a small way to chip away at the bigger problem.
Snowmelt is pivotal for adding water to the Colorado River's major reservoirs, and any hope of refilling the beleaguered storage pools, even a little bit, hinges on snowy winters.
Even major rains like the storms that swept through the Four Corners in recent days pale in comparison to the amount of water that flows into reservoirs from snowmelt.
This October, rain-charged inflows added about 850,000 acre-feet of water to Lake Powell, the nation's second-largest reservoir. By comparison, average spring inflows to the reservoir are around 5 million acre-feet.
An acre-foot is roughly the amount of water it would take to cover a football field with one foot of water. The Arizona Department of Water resources says one acre-foot is roughly a year's supply of water for three homes in the Phoenix area.
However, after more than two decades of drought and climate change, Templeton said, it would take about five back-to-back winters of above-average snowfall in the Rockies to get Lake Powell halfway full.
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