What Water? Whose Water? What Happened?
At winter’s end early this year, the snowpack was low; the spring runoff forecast was dismal. Two federal agencies, the Bureau of Indian Affairs and the Bureau of Reclamation, stored all the native Rio Chama runoff in El Vado and Abiquiu to ensure a full supply for the six Middle Rio Grande Pueblos prior and paramount water rights. Of the approximately 34,000 acre-feet of water stored, 13% was used and 5% evaporated. Winter arrived again with 26,000 acre-feet remaining in storage.
Federal and state water agencies planned the release of this water. This article summarizes the fate of the release as the water flowed downstream.
A block release of the remaining 26,000 acre-feet of stored water began November 30. Water agencies intended that it flow unused into Elephant Butte Reservoir to reduce this year’s large underdelivery of the water that belongs to water users below Elephant Butte Dam. As of November 24, 2025, the Rio Grande Compact accounting model showed New Mexico’s deliveries were about 39,000 acre-feet short of the delivery obligation.
The hydrographs below show vividly what happens when water is poured down losing reaches of a river. We hope the OSE and ISC will collect a complete data set of this event, analyze it, and report their technical analysis and full data set.
Let This Set of Hydrographs Tell Their Story
Let’s start with a summary of the MRG geography.. The Cochiti Dam releases drive the downstream responses, as the hydrographs above illustrate. The step increases in Cochiti Dam releases are in response to Abiquiu Dam releases to the Rio Chama upstream. The Abiquiu Dam releases flowed down the Rio Chama to its confluence with the Rio Grande, and down the Rio Grande into Cochiti Reservoir. Cochiti Dam releases were stepped up or down once daily to match the total inflows to the reservoir.
During the block release period, the Rio Grande below Cochiti Dam gage steps up rapidly to 2,000 cubic feet per second (cfs) for six days and then steps down. The Cochiti Dam release mimics the Abiquiu Dam release on the Rio Chama, which was sustained at 1,400 cfs for six days. The difference is water from the northern Rio Grande, measured at the Rio Grande at Embudo gage.
2025: An Extremely Dry Setup.
How much of the release made it to Elephant Butte? The answer begins with the conditions leading into the release. Rio Grande flows in 2025 set record lows. The runoff was small and brief. After the runoff ended prematurely in May, the riverbed was dry through Albuquerque and more extensively downstream for several months.
River water users did their best to meet their needs with increased groundwater pumping.
Floodplain and riparian vegetation— cottonwoods, willows, salt cedar, Russian Olive — drank from the wetted soil zones above the shallow groundwater table.
How Much Made It to Elephant Butte? Peak Flows at Downstream River Gages Reveal Large Losses
Individual hydrographs show consistently lower peak flows as the block release moved down the river. The pattern is clear.
- Cochiti Dam release: Peak flows of 2,000 cfs were sustained.
- Bosque Farms: The peak flow is much lower, delayed, and smoothed. Comparing the flow downstream of Albuquerque with the Cochiti Dam releases shows large losses through the Albuquerque reach.
- San Acacia: The peak is lower still at this river gage at the head of the Socorro Valley, but not by a huge amount. The losses between Bosque Farms and San Acacia are relatively small.
- San Marcial (floodway): The peak is further reduced and delayed. The river above San Marcial suffers especially high river losses. The river channel is perched several feet above the adjacent floodplain, trapped between levees on an elevated bed of accumulating sediment.
- Elephant Butte Narrows: As of December 18, only a muted remnant of the original pulse has made it Elephant Butte Reservoir as of December 18.
Reclamation’s 1950s low-flow conveyance channel at San Marcial is added to the San Marcial river flow as the total surface flow moving downstream at that river location. Both flows come together before the Narrows gage.
Comparison of the San Marcial and Elephant Butte Narrows hydrographs shows significant intervening losses as the water flows down a temporary channel dredged by amphibious excavators to the Narrows. The channel is dredged through the top layer of the thick sediment beds that accumulated when the Elephant Butte Reservoir was routinely full and the pool reached almost all the way north to San Marcial.
Summary – What the Hydrographs Show
Each downstream gage captures a smaller and flatter version of the same release, indicating significant losses in every reach. Our calculations show the river lost more than 40% of the block release.
The Embudo gage provides a steady upstream reference.
The Abiquiu release provides a controlled input.
The Cochiti release shows their combined signal.
Everything downstream shows systematic attenuation clearly visible in the curves.
The Bottom Line
The block release was intended to move Prior and Paramount stored water downstream to Elephant Butte Reservoir.
The hydrographs show that much of the water never made it.
The Middle Rio Grande took it — into the channel, the banks, the shallow aquifer, and the steady flow to deep groundwater pumping zones.
Downstream river gages reproduce the Cochiti Dam stepped pattern, particularly the steps down. You can trace the first big drop. These data show a pattern that is consistent with what would be expected after a long season with a dry river, accelerated groundwater pumping, major riparian and domestic withdrawals from the shallow aquifer, and poor channel conditions.
This is more evidence that our current water uses can’t be sustained. Sobering thoughts to consider as a new, even drier year begins.