If you have ever been to modern San Marcial, New Mexico – or what is left of it – the notion of an 86-pound catfish requires some explanation.

The spot where D.C. George hooked his record catfish is today ragged scrubland. But for a brief, shining, extremely odd period of time in the 1940s and ’50s, Lake San Marcial was a big deal.

It was popular with the hook and bullet set, while on occasion also swallowing Atchison, Topeka, & Santa Fe locomotives (so, less popular with the railroad).

It was the subject of dueling litigation. The railroad was mad about the swallowed locomotives, blaming the federal government for causing the lake. The Hunters, owners of the fishing resort, got mad when the federal government decided to drain (or maybe fill?) the lake, so they sued too.

It is a useful example of a common sequence of events when we engineer a river:

1. Change a river with engineering.
2. Something weird happens.
3. People and ecosystems improvise, optimizing around the new state.
4. But the new state causes problems, too.
5. Try to fix these problems.
6. People who had optimized around the new state, or who value the ecosystem’s optimization around the new state, are pissed about the change.

Located 120-ish river miles down the Rio Grande from Albuquerque, the town of San Marcial was a happening place in the early 1900s – major railroad employment center, heart of a what was, in the romantic retellings, a lovely little farming valley with its sibling Tiffany just up river and Val Verde across the narrow desert valley.

As the retellings often point out, it had an opera house. (I’m a writer. I get it. How can you resist an opera house.)

Upstream from a geomorphic bottleneck – the volcanic Black Mesa to the east, a string of sediment-laden arroyos coming in from the west – the San Marcial reach of the Rio Grande has long been a trouble spot for those bent on settling on the valley floor. Flooding was not uncommon. But with the 1916 completion of Elephant Butte Dam to the south, the flooding got worse. Elephant Butte’s full pool elevation is downstream of the bottleneck, but as a reservoir encroaching from downstream slows a river, sediment deposition creeps upstream, often well beyond the reservoir’s actual high water mark.

Whether Elephant Butte’s presence, the sediment deposition, actually caused the flooding that in 1929 ended San Marcial’s opera house days would be the subject of some legal debate in the decades that followed. A federal judge in 1960 ruled that the federal government, builder of Elephant Butte, was not to blame but, as I said, further research needed.

Base Level, Aggradation, and Grade

The modern scientific consensus seems to be that, duh, of course Elephant Butte caused the demise of San Marcial.

Perhaps the most notable example of the aggrading wedge upstream of a reservoir is at the Elephant Butte reservoir, built in 1912 on the Rio Grande about 300 km downstream of Albuquerque, New Mexico (Eakin, 1936). By the 1930s, the Rio Grande had aggraded many kilometers upstream of the head of the lake. Because the sediment load was sand, most of the aggradation was in the channel with the creation of natural levees. Drainage from the distal land on to the floodplain was blocked from entering the stream by the natural levees and thus the floodplain became a wetland and was even ponded in many places. Near the reservoir, the stream level was superposed, or higher than the floodplain. By the 1930s, a local village, San Marcial, began to be flooded and was finally evacuated (Eakin, 1936). It was feared that the wedge of sediment would eventually extend all the way to Albuquerque but that never happened (Mackin, 1948).

– Trimble, Stanley W. “Streams, valleys and floodplains in the sediment cascade.” Sediment cascades: An integrated approach (2010): 307-343.

In their seminal paper Base Level, Aggradation, and Grade, Luna Leopold and William Bull explained how a river slows and drops is sediments as it reaches a controlling base level. The most obvious example is the ocean, which on geomorphological time scales is relatively stable. The result is a wedge of sediment well upstream of the ocean itself. This also happens when we dam a river. The reservoir level acts like a mini-ocean, and the sediments back up well upstream of the of the reservoir level itself as water slows down and spreads out.

Natural constraints do this as well – constraints like the pinch point between the volcanic mesa to the east and arroyos dumping in their load from the west just downstream from the ill-fated community of San Marcial.

A tale of catfish and willow flycatchers

The weird thing for today’s blog post is the lake, which seems to have emerged in the 1940s, perhaps following the floods of 1941 and ’42, which pushed Elephant Butte to its high stand, depositing sediment in this reach and in general causing a geomorphologic mess – not a mess for the river, the river’s just doin’ river stuff, but a mess for the humans who had taken on the obligation of managing the Rio Grande.

Like, trains kept falling into Lake San Marcial, but more importantly for the task of river management, water that humans wanted to hurry on down to Elephant Butte so folks downstream could water their crops was instead spreading out in the “lake” and surrounding swamps. The river no longer flowed here, and New Mexico as a result had fallen hundreds of thousands of acre feet behind in its obligations under the Rio Grande Compact to deliver water to Elephant Butte Reservoir for use in Southern New Mexico, Texas, and Mexico.

Draining the lake and those swamps was as a result a passionate imperative among New Mexicans in the 1950s, as we essentially agreed to federalize the river so the taxpayers of the nation, after helping create the problem by subsidizing Elephant Butte Dam for our benefit, were now asked to again subsidize the fix to the problem created at Elephant Butte’s upstream end.

The Middle Rio Grande Project

The Flood Control Act of 1948 (and a subsequent 1950 iteration) authorized the US Bureau of Reclamation and the Army Corps of Engineers to, among other things, “fix” the San Marcial stretch of the Rio Grande- “river rectification” was the formal terminology of the day. To do that, the Bureau dug what amounts to a second river channel, which today we call the “Low Flow Conveyance Channel,” alongside the river’s old channel. Here’s the explanation from Chris Gorbach’s 1999 history (found in these conference proceedings):

In 1951, President Truman gave Reclamation special authority to start channel construction immediately. Work on the low-flow channel and clearing a floodway for passage of higher flows began in October of that year. Construction on the low-flow channel continued throughout the ’50s. A first phase, the so-called San Marcial Channel, was completed at the end of 1953. Diversions through a heading near the southern end of the Bosque del Apache began in November of that year. Extension of the low-low channel upstream to San Acacia was completed in 1959. When completed, the low-flow channel extended some 70 miles from San Acacia to a point just above the narrows of Elephant Butte Reservoir.

By 1956, the lake where D.C. George hooked that 86-pounder was dried up, turned to grazing land for cattle, and the Hunters were suing the federal government over the loss of their fishing resort. Further research needed on the demise of San Marcial Lake. The news coverage of the day suggests the Bureau of Reclamation diverted silt-laden Rio Grande water into the lake to fill it up. The Hunters called that negligence, the Bureau responded that, no, it was exactly what they intended, and were authorized by Congress to do.

Laguna de Fray Cristóbal

Three quarters of a century after the demise of San Marcial Lake, we’re experiencing a repeat. About ten miles downstream, a large body of water has emerged, apparently of some interest to anglers, certainly of great interest to Southwestern Willow Flycatchers (ecosystems improvise, optimizing around the new state), and also certainly of extraordinary interest to the water managers of 2025 charged with carrying out the obligations we took on as a community when we began engineering the Rio Grande more than a century ago.

Off to the west of the end of the Low Flow Conveyance Channel are 100 acres of open water surrounded by wetlands that are, from a “water in the desert” environmental aesthetic perspective, a delight created by leaks and levee failures in a stretch of the river that doesn’t get a lot of love. The Bureau of Reclamation has even installed gizmos to divert some of the water now flowing down the Low Flow Conveyance Channel into this wetland, beloved by the endangered flycatcher. But in a world in which competing and conflicting values include a desire to move water to farms and cities downstream, in the process meeting the legal requirements of the Rio Grande Compact, the River Mile 60 pond is not universally beloved. Here’s Middle Rio Grande Conservancy District CEO/Chief Engineer Jason Casuga in a letter to the state last summer:

What was originally a failure in infrastructure has now become a managed habitat feature by the federal government. The breach channel eventually makes its way back to the river some 7 miles downstream of RM 60. MRGCD is concerned about the depletions taking place within the breach channel and adjacent floodplain habitat when you consider the area of inundation is likely between 900 to 1,500 acres and has a corresponding evapotranspiration rate of more than 5.5’ per acre annually (based on OpenET).

At a time New Mexico is falling farther and farther behind on its compact obligation to communities in Southern New Mexico and Texas, this is a problem. It is an example of the sometimes competing and conflicting values at play when we take on the enduring obligation of engineering a river.

In a letter last week (July 17, 2025) to the Bureau of Reclamation, New Mexico Office of the State Engineer General Counsel Nat Chakeres gently suggested that diverting water into the wetland was not in keeping with the aforementioned Flood Control Acts of 1948 and ’50, which authorized Reclamation to bail us out of the messes that Reclamation in part created by building Elephant Butte in the first place. Chakeres’ argument is that the acts of Congress setting the whole thing up explicitly prioritized delivery of Compact water.

In summary, the sole authorized purpose of the LFCC is to convey water to Elephant Butte for compliance with the Rio Grande Compact. If water is diverted from the LFCC and consumed for habitat purposes, that is water that could have been delivered but was not.

There’s been some discussion about what we should call the River Mile 60 pond. A number of names have been suggested, but none capture the grace of this much-maligned, often forgotten but, to my eyes, magnificent stretch of the Rio Grande.

Nearby is the old Paraje de Fray Cristóbal, a hardscrabble stopping point on the old Camino Real. I suggest we call it “Laguna de Fray Cristóbal.”