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A dry spring is dampening hopes for another year of high water flow in the Colorado

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A dry April in the Colorado River basin has dashed hopes of a second straight record year of high flows and thereby affecting Lake Powell's water reserves, government hydrologists say.

The result is likely a holding pattern for drought response over the next two years, according to the U.S. Bureau of Reclamation. It is unlikely that water levels in Lake Powell and Lake Mead will rise as they did after the heavy snowpack that accumulated in the winter of 2022-2023, but it is also unlikely that the Southwest will initiate a new level of water conservation measures.

The mountain snow season started dry, increased sharply in the middle and came to an abrupt halt in April.

“We've kind of had a yo-yo in terms of precipitation and snowpack,” reclamation hydrologist Heather Patno told members of a Glen Canyon Dam Adaptive Management Program working group Wednesday.

More than 40 million people rely on urban and farm water supplies from the Colorado River in seven states, including Arizona. Drought restrictions had no impact on water users in homes and businesses, but did result in restricted flows to some farmers, particularly in Pinal County.

With the exception of the Colorado headwaters and the Verde River in Arizona, most areas of the seven-state watershed recorded below-average snow and rain amounts in April, according to the Colorado Basin River Forecast Center. Snowpack water content, which was generally above average across the region in late winter, changed to normal or below average as meltwater began to flow toward Lake Powell.

“April precipitation was quite poor as a percent of average for most of the region,” National Oceanic and Atmospheric Administration hydrologist Cody Moser said during the forecast center’s monthly briefing. Much of the watershed will receive only half to 70% of normal April precipitation.

The number of snowpacks decreases during a drier April

For the water year that began in October, rainfall totals in the areas that flow to Lake Powell were about 97% of the 30-year average that month, he said.

A relatively dry month over the large reservoir had reduced the snow-water equivalent value from April 1, which was 113% of the median, to just 89% by May 1. The snow water equivalent describes the amount of water that would be created by melting snow.

Reclamation, which manages Powell's outflows behind Glen Canyon Dam, now predicts the amount of water flowing to the reservoir by the end of the flow season in July will be 81% of average, a total of 7.9 million acre-feet corresponds. With the agency set to release 7.48 million acre-feet toward Lake Mead this year, Powell's storage capacity is not expected to change significantly.

The utilization rate is currently at 34% and, according to the agency's calculations, will most likely be at 37% at the end of the year.

That mediocre outlook contrasts with a year ago, when big snowfalls led Reclamation to predict runoffs at 172% of average, giving both Powell and Mead a respite from the disaster that had been building over two decades of drought .

Negotiation of long-term guidelines

Although this year's meltwater is unlikely to cause the reservoirs to swell any further, a year in which they are not further depleted can be considered a success. If current predictions hold, the agency expects emergency water conservation measures taken this year in the Southwest to keep supplies stable for at least a few years. Officials announced in March that the negotiated plan calls for 3 million acre-feet of water storage by 2026. The agency signed off on the plan this month.

Additionally, to ensure stability, states, tribes and federal officials are negotiating longer-term policies that mandate further water conservation unless a wave of rain replenishes reservoirs, a level not yet reached this century. The US Department of the Interior is expected to propose its chosen guidelines by the end of the year.

In Arizona, the Salt River Project's water supply outlook is good for the second year in a row. The Phoenix metropolitan area supplier said its Salt and Verde watershed reservoirs have been at 93% capacity since May.

Brandon Loomis covers environmental and climate issues for the Arizona Republic and azcentral.com. Reach him at brandon.loomis@arizonarepublic.com.

Environmental reporting at azcentral.com and in the Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust.

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