Water release for irrigators delayed due to storm damage

NEW INFORMATION (July 3): With recent rains in the Middle Rio Grande Valley, Anne Marken, water operations division manager for the Middle Rio Grande Conservancy District, said the rain inflows have helped bring down demand and bolster supply in the river, which will help New Mexico in its deliveries to Elephant Butte under the Rio Grande Compact obligations.

“The rains have also bought us some time before we see irrigators go into rotations, but if we do not continue to see rain inflows to the river, farmers will likely be on rotation in the coming weeks,” Marken said.

Heavy rains in northern New Mexico won’t help local irrigators in the coming months.

Intense rains in the community of Medanales in Rio Arriba County along the Rio Chama swept large amounts of sediment out of arroyos and into the river, forming a plug that caused the river to change paths, flooding adjacent agricultural lands and homes.

“This is obviously upstream of the middle valley,” said Anne Marken, water operations division manager for the Middle Rio Grande Conservancy District.

The plug in the river has now essentially trapped the district’s stored water upstream, meaning as the Rio Grande flows begin to dwindle, there won’t be a release of additional water for irrigation in July as planned.

Because the Rio Chama is blocked, the U.S. Corps of Engineers, which owns and operates Abiquiu Dam, has entered flood operations and reduced flows out of the dam to 100 cubic feet per second. The corps will keep the flow at that rate until the plug is removed by the U.S. Bureau of Reclamation, Merken said, an operation that could take up to a month to complete.

“The Bureau of Reclamation is mobilizing equipment to remove the sediment,” she said. “It could take up to four weeks. I do think that’s the worst case scenario, but it’s good to plan for the worst case.”

MRGCD’s stored San Juan Chama water is upstream of Abiquiu in Heron Lake, so while the Corps is in flood operations and BOR is removing the sediment plug, the district cannot access and release any of its stored water.

“Functionally, we are on a ‘run of the river’ system right now. We have no ability to release (stored) water,” she said last week. “Right now, the flows are about what we need to meet ag and conveyance demand, but those flows are dropping rapidly. By Monday, I estimate we’ll be below the flow we need to meet demand.”

That means farmers and irrigators in the Middle Rio Grande Conservancy District should expect to be on rotation very soon, Marken said, as the district “tries to equitably distribute water. Farmers should expect extended periods between irrigation events.

Operations are dependent on supply, and rain can change all of this. Once they do remove the sediment plug, the district plans to release the San Juan Chama water.

“This is really poor timing. We hope for rains this time of year but this threw us a curve ball.”

The only water the district can store is its 2024 allocation of San Juan Chama water, which is imported from the San Juan basin in northwest New Mexico and southwest Colorado. The SJC water can be stored because it isn’t subject to Rio Grande Water Compact restrictions, which only applies to “native” water generated in the Rio Grande Basin.

The compact agreement guarantees a certain amount of water will be delivered south to Texas each year. When New Mexico is in compact debt — which is the current situation — storage of native waters is prohibited.

“Because it comes from another basin, it’s not constrained by the compacts so we can store the San Juan Chama water upstream,” Marken said. “Once the native inflow generated within the Rio Grande Basin is not enough to meet conveyance for agricultural demand, that is when we release (stored) water to supplement what the basin produces naturally and what farmers need.”

Marken said the expectation was to release SJC water in late June this year, depending on rain fall.

“How much we need to release depends on the natural rain fall. We were expecting storage water to last three to five weeks,” she said.

Once the district has released all of the San Juan Chama water, it goes to what is called a “run of the river” system, Marken said, where the district only has what is naturally produced in the basin to divert for irrigation use.

“Typically into late summer and early fall, that is not enough to meet demand,” she said. “We were expecting to start the release (of SJC water) towards the end of this month. I thought we could be on ‘run of the river’ by mid July and trying to equitably distribute (water) to farmers. That is what I was forecasting.”

When the district is on “run of the river,” irrigation is done on a rotational basis, and the length of time between rotations depends on the flow.

“I’ve been telling farmers to be prepared for extended periods between deliveries,” the manager said.