Diverting the Rio Grande into a grown-over, decades-old canal could cut New Mexico’s water debt

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A man-made channel built decades ago to expedite Rio Grande waters to Elephant Butte still exists, parallel to the Rio Grande. Credit: Bella Davis.

Decades ago, Norm Gaume, a water advocate, paddler, and former director of the Interstate Stream Commission, hauled a canoe to central New Mexico, thinking he’d float down the Rio Grande through the Bosque Del Apache National Wildlife Refuge. But when he arrived, he found no water in the river.

“None,” he said. “Because it was all in the Low-Flow Conveyance Channel.”

The channel is an obscure chapter in New Mexico’s water history that harkens to the 1950s, when New Mexico faced a growing water debt to Texas and needed to move water downstream more efficiently. The best way, they determined, was to route the water away from the riverbed into a 70-mile, rock-lined, narrow channel that would speed it downstream.

The river flowed into the engineered channel beginning just above Socorro for two decades, until its operation was suspended in the early 1980s. 

Even decades later, groundwater seeps and overflow from farms spill into it, so it’s possible to stand on a bridge and watch the flow of what is essentially an irrigation ditch that once held an entire river.  While the Rio Grande meanders red and muddy through sandbars, the channel is uniformly deep and the water in it swift. Willows, cattails, and tamarisk have grown along the channel’s banks and, beyond the gravel service road that frames it, mature cottonwoods. 

The channel might have remained only an engineering artifact from the mid-20th century, an era when people expected to be able to dominate nature. But New Mexico once again owes Texas a massive water debt, so water managers are considering resurrecting the original purpose of the channel.

Diverting water from the Rio Grande to the channel would move it more easily to the state’s southeastern neighbor, satisfying legal obligations from an 85-year-old compact between New Mexico, Texas and Colorado. 

But the era of dominating nature is gone. The Endangered Species Act, with its protection of a fish species called the Rio Grande silvery minnow, blocks diverting all of the river to the channel as water managers’ predecessors did. When and how much they divert will have to be done with that finger-length fish in mind. 

Still, environmentalists worry water managers won’t get the balance right, particularly as climate change is creating a hotter, drier Southwest, diminishing the amount of water flowing in a river that’s already over-taxed. The move, environmentalists say, could compromise habitat for some of the state’s threatened and endangered species, in addition to dewatering what some consider one of the wildest sections left of the Rio Grande. Some fret that the state is again failing to plan holistically for a future that includes rivers, and a bosque of cottonwood trees that people love. 

Cottonwoods in the Rio Grande bosque turn vivid yellow each fall. Credit: Marjorie Childress

Problems with the Rio Grande running short of water began almost as soon as New Mexico, Colorado and Texas signed the compact that divided the river’s flow among the states in 1938. In the early 1940s, high water years created a swampy wetland and string of ponds between muddy swells for miles at a time above Elephant Butte Reservoir. The river ceased running downstream, and deliveries to Texas dwindled.

By 1953, water owed to Texas neared 500,000 acre feet (an acre foot is the amount of water needed to cover one acre of land one foot deep, or about seven times the amount of water used annually by the average Albuquerque resident). So the U.S. Bureau of Reclamation built the Low-Flow Conveyance Channel, and for most of the 1960s and 1970s, the entire river was re-routed into the channel most of the time. By steering around a thirsty riparian area, the channel saved an estimated 60,000 acre feet of water each year. The state’s water debt to Texas was eliminated by 1972. 

The compact measures water delivered by Colorado to New Mexico at the state line, but water that’s designated for Texas from New Mexico is measured just above Elephant Butte, more than 100 miles upstream of Texas. 

Problems getting river water to Elephant Butte have re-emerged. The reservoir’s dam backs up the river for 40 miles. Where water slows, sediment drops out of it, creating a sprawling, muddy delta. Water reaches that delta and spreads out and evaporates, or sinks into the ground.

Maintaining something that looks like a river corridor requires amphibious machines to routinely dredge a channel. The section of river north of Elephant Butte, the San Acacia reach, has developed a reputation for soaking up all the water sent into it and often dries out.

The U.S. Bureau of Reclamation is looking at ways to speed water through that reach by excavating a deeper river channel and removing some thirsty non-native vegetation. But time constraints have compelled the Bureau and state and local water managers to assess rehabbing the channel to move water through it again.

“We’re almost in an emergency situation in needing to improve our deliveries to Elephant Butte for the compact, so I think, timing-wise, it’s going to be a lot faster to fix up the low-flow conveyance channel,” said Page Pegram, Rio Grande Basin bureau chief for New Mexico’s Interstate Stream Commission.

That the Legislature included $10 million in the just-passed state budget for maintenance to improve river flows into Elephant Butte, including millions likely to be earmarked for the low-flow conveyance channel, demonstrates the seriousness with which New Mexico policymakers are treating the situation. 

Stephanie Russo Baca, who chairs the board of the Middle Rio Grande Conservancy District (MRGCD), which formed in 1923 to regulate the Rio Grande’s erratic flows for the 174 miles between Cochiti and Elephant Butte dams, calls it a “Hail Mary effort to get the water instead of it just evaporating. … If you’re going to deplete, don’t let it deplete just into the air.”

Preserving what exists now along the Rio—irrigated alfalfa, pecan orchards, fields of cotton, crops of chile, onions, and melons—relies on water. Downstream, Texas uses the water for vegetables, cotton, sugarcane, and the country’s third-largest source for citrus, a crop valued at $200 million a year. When people chastise farmers in the Middle Rio Grande Conservancy District for using so much of the Middle Rio Grande’s water, Russo Baca points out, so does the bosque of cottonwood trees and willows lining the riverbank. Statewide, agriculture, including livestock, consumes about 77 percent of the water used. And with climate change, everything—crops, streamside plants, even the air—will suck up more water. 

A map at the Bosque Del Apache National Wildlife Refuge shows the low flow conveyance channel running parallel to the Rio Grande. Credit: Bella Davis

Even with dramatic measures to conserve water in 2021, including shortening the irrigation season, New Mexico missed its downstream delivery requirement to Texas. And despite a plentiful monsoon season in 2022, the total water owed to Texas dropped below 100,000 only because the Interstate Stream Commission was able to negotiate a credit for 32,000 acre feet of water the Bureau of Reclamation released from Elephant Butte in 2011.

That credit has done little to ease minds or reduce pressures to conserve water. If the amount owed reaches 200,000 acre feet, New Mexico could lose control of its water to the U.S. Supreme Court, which handles disputes over the Rio Grande Compact. That’s a crisis water managers are looking to the low-flow conveyance channel to help mitigate. 

“Granted, the way that the low-flow was used back then is not a way in which the district or probably any other water agency envisions using it, but we think there is a middle ground there,” said Casey Ish, water resources specialist with the Middle Rio Grande Conservancy District.

That middle ground might include using the channel during high-intensity monsoon rain storms to capture and fast-track that water downstream. Reclamation is planning a project this spring that would start on that effort by constructing a temporary outfall—a canal that returns unused water—to the river from the channel just south of the Bosque del Apache National Wildlife Refuge. The channel has been functioning as a drain for the river valley. The outfall would reconnect that often pooled water with the river channel so it can make its way to Elephant Butte while  the end of the channel is prepared to expedite water downstream if diversions resume.

Tens of thousands sandhill cranes winter at Bosque Del Apache National Wildlife Refuge. Credit: Bella Davis.

Modeling work on the Rio Grande assessed how big a difference the channel might make, Gaume said, and the indications were that the increased water delivered through the channel roughly matched the amount of water gained by eliminating about half the irrigated agriculture in the middle Rio Grande valley. 

“So it’s a big deal,” he said. “And always has been a big deal.” 

Mike Hamman, previously the conservancy district’s director and now the state engineer, also lists re-opening the channel as a way to address “high loss” in that reach of the river but agrees it has to be done in an environmentally conscious way. The channel predates the Endangered Species Act and wasn’t operated before with the wellbeing of the Rio Grande silvery minnow, one of the river’s flagship endangered species, in mind.

“The LFCC today would likely never function as it did in the 1960s and 1970s due to the environmental impacts,” Jason Casuga, CEO and chief engineer of the MRGCD, explained via email to Sen. Martin Heinrich’s staff shortly after a meeting to discuss a water conservation program aimed at farmers. 

“We’d like to use it differently, so it’s not essentially drying the river in that reach,” Pegram agreed. “I don’t think anyone wants to operate it without considering environmental impact.”

The U.S. Fish and Wildlife Service is “definitely involved” in conversations around reopening this channel, said Debra Hill, large river restoration and recovery program supervisor with the agency. It is helping to identify where the river provides habitat for a trio of endangered and threatened species: the Rio Grande silvery minnow, southwestern willow flycatcher, and yellow-billed cuckoo. So far, none of the work to remove brush and maintain roads along the channel looks likely to injure endangered Rio Grande silvery minnow—it’s never been good habitat for them—and the one nesting Southwestern willow flycatcher in the area was unlikely to be disturbed by the work, according to the Service’s analysis for the Bureau of Reclamation.

Where the river itself is not providing that habitat, maybe it would be okay to route a portion of the river into the channel, Hill said. Generally, the agency prioritizes working in the river channel itself, even when ditches might be a faster way of moving water downstream.

The Rio Grande has always been a boom-and-bust waterway, with wet years followed by dry years. But the Southwest is entering uncharted territory. 

“I don’t think we can look at our historical data and make decisions into the future anymore,” said Hill. “We have to have a paradigm shift in how we look at water in the middle Rio Grande, and probably the entire state, and probably the entire West. We’re going to have to have a paradigm shift to realize, we live in a desert, and it’s only going to become more of a desert.”

To environmentalists, the idea of reopening the channel prompts a slew of questions and concerns, most of which hinge on whether these water management institutions are looking at the bigger ramifications in ways that, historically, they haven’t. 

Looking elsewhere in the Rio Grande Basin, there’s a stack of instances where the river has been abandoned. Downstream of Elephant Butte, it flows only in rare floods or while delivering irrigation water. Below El Paso, all the river’s water flows through irrigation ditches, leaving a dry channel. The “Forgotten Reach” through Texas, is even more rarely wet and is largely overgrown.

Given the compact crisis, Paul Tashjian, director of freshwater conservation for Audubon Southwest, is concerned that the channel might be revived and all the water entering the San Acacia reach, just north of Elephant Butte, redirected into it. 

“That would be a dead river,” he said. 

What might rank among the most important components of the river to preserve isn’t a perpetual flow, but how the water level surges with melting snow in spring.

Everything along the Rio Grande evolved with an erratic river that ran big and high with snowmelt in spring, then retreated. Cottonwood seeds only sprout on muddy banks. Willow seedlings likewise rely on damp ground. Birds nest above that snowmelt-thickened river. The silvery minnow spawns its eggs into the current, but they need to drift into slower channels and pockets of stiller water in the floodplain to grow up. 

Restoring the Rio Grande silvery minnow has required water for the fish to live in, but it’s also prompted federal and state agencies to re-engineer a “pulse flow” of water in spring to mimic snowmelt runoff that cues minnows to spawn. To do that, they release water from dams upstream timed to boost flows the way melting snow would.

“If you look historically, that spring pulse was the ecologic driver. That is how the system functions,” Tashjian said. “If you could maintain that, there are so many species that are keyed into that—it’s not just the minnow, it’s the cottonwoods and the songbirds.”

At the United Nations Biodiversity Conference in December, a global gathering on staving off the rampant loss of nature, biodiversity advocates built a giant Jenga tower to symbolize the notion that all these fish, birds, and plants are like building blocks. Only so many pieces can be lost before the whole tower topples, and which and where and how many species the planet can lose without jeopardizing human life, too, isn’t any clearer than the next move in that game.

Gina Della Russo worked as an ecologist for the Bosque del Apache National Wildlife Refuge for 17 years, aiding native plants in reestablishing on about 4,000 acres. The wildlife refuge also relocated the river channel away from the low flow conveyance channel into areas where it will build backwaters and wetlands for fish and bolster habitat for meadow jumping mouse, southwestern willow flycatchers, and yellow-billed cuckoo. One of her questions has been how reactivating the low flow conveyance channel might affect those nascent wetlands. 

“As a short-term solution, under the conditions we’re in right now, you try whatever you can to get water balance,” she acknowledged. “It’s a human condition, we react, so we think of things that may get us out of problems for a year or two, but will they actually solve the long-term problems of the river in this reach?”

This article was supported by The Water Desk, an independent journalism initiative based at the University of Colorado Boulder’s Center for Environmental Journalism.

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