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Clock ticking on Gila dam decision

The Gila River reflects the glowing Mogollon Mountains as the sun sets. The Interstate Stream Commission is deciding whether to partially dam the river in southern New Mexico. (Jim Thompson/Albuquerque Journal)

The Gila River reflects the glowing Mogollon Mountains as the sun sets. The Interstate Stream Commission is deciding whether to partially dam the river in southern New Mexico. (Jim Thompson/Albuquerque Journal)

Copyright © 2014 Albuquerque Journal

As New Mexico’s Interstate Stream Commission heads into the final stretch of a decision a decade in the making – whether to partially dam the Gila River – the federal agency best known for building dams says the costs far outweigh the benefits.

The eight-member commission has fewer than five months before it must communicate a decision to the Interior Department about whether to divert up to 14,000 acre-feet of water from the Gila River under the 2004 Arizona Water Settlement Act.

It’s a decision that has stirred debate among those who worry about the financial and environmental costs of diverting water from a river often referred to as New Mexico’s last “wild” river, and others who believe that a drought-prone state cannot miss a chance to take water when it’s offered.

Three proposals to divert water through a series of partial dams, reservoirs and pipelines – known as “diversion” projects – are on the table. So are 15 alternative projects, mostly hinged to conservation, reuse and watershed restoration.

“The cost and benefit analyses indicate the costs exceed benefits for all of the diversion proposals,” as well as for five of the alternative projects, according to the Bureau of Reclamation’s final appraisal, a more than 400-page analysis issued earlier this month.

The benefits evaluated include water supplies for agricultural, municipal or industrial use; recreation, water quality, and fish and wildlife. Costs include construction, taxes, design and construction contingencies, and non-contract costs.

The settlement resolved a long-standing dispute, dating back to the 1960s, regarding how much water Arizona and New Mexico could respectively take from the Colorado River system.

It made available to New Mexico $66 million – nearly $100 million today, accounting for inflation – that could be used to pull water out of the river via a diversion, for conservation efforts or both. Another $62 million is available under the agreement to put toward a water diversion project only.

The costs of a diversion range from $41 million to nearly $600 million depending on the project, according to the Bureau’s analysis. They are estimates of conceptual designs fleshed out to about 10 percent of the total design, according to ISC Director Estevan López.

Those estimates don’t yet take into account the full scope of the complex engineering that would be required to partially dam the river, create storage reservoirs within canyons and construct a pipeline to haul the water out of the Gila system to end users – possibly farmers, ranchers or municipalities, although the consumer has yet to be determined.

The Gila River is often called the “last free-flowing river” in New Mexico, given that no major infrastructure interrupts its course.

In the winter, the river curls like a sapphire ribbon through a monotone landscape of leafless trees and bare brush. Some years, melting snowpack will fill the river, flooding secondary channels where plants and animals depend on these peak flows to survive – although drought has made those high times few and far between, according to Martha Cooper, a field representative for The Nature Conservancy.

By late summer, depending on the frequency and ferocity of storms during the monsoon season, some areas that were bare in the winter and the hot summer months will again be covered by the rushing water. It’s a river whose depth rises and falls with the seasons, whose course shifts with periodic floods.

Although the settlement allows the diversion of 14,000 acre-feet of water from peak flows only, the Bureau report shows that amount has not always been historically available and bases its calculations on an average annual yield of 12,000 acre-feet. An acre-foot, or roughly 326,000 gallons, can supply one to two U.S. households with all the water they need in a year.

In addition to the variable availability of water, the Bureau acknowledges in its report that the geology of the proposed reservoirs “is the most significant unknown associated with all alternatives” and notes that the final costs of implementing any of the proposals won’t be known until more detailed feasibility studies are done.

“It seems the more we know, the higher the costs go,” said Sharon Wirth, freshwater program manager for the Audubon Society in Albuquerque, which supports conservation efforts instead of a diversion. “Very important engineering components are missing as of yet. When will those be evaluated and what will the costs be?”

It’s also unclear who would pay for a diversion, given that most estimates put the costs well above what is available under the settlement.

An ISC meeting scheduled for Aug. 26 kicks off the decision-making process.

Commissioners will hear summaries of the project proposals and of the studies completed so far, as well as presentations from advocates and detractors of a diversion, said López, who as ISC director is a voting member of the commission.

López, who has been nominated to head the Bureau of Reclamation, said he plans to recommend the commissioners postpone making a preliminary decision on whether or not to choose a diversion project or one or more of the alternatives until additional studies are in.

“There is a lot more analysis that still needs to be done,” he said. “We’re trying to give sufficient information to our commission to make as informed a decision as it can.”