San Juan River water administration under a microscope as drought plagues Colorado River basin
As the federal government directs more and more scrutiny on the Colorado River and its tributaries, the New Mexico Office of the State Engineer is developing systems to better account for how much water is diverted from the San Juan River and how much is returned in hopes of demonstrating to both federal partners and other states that rely on the Colorado River that New Mexico is meeting its obligations.
Shawn Williams, the district manager for the Office of the State Engineer, said there will likely be tighter administration of water in the future.
New Mexico’s source of Colorado River water is through the San Juan River, along with its tributes like the Animas River. These rivers flow through San Juan County, though the water from the San Juan is also used by people in Albuquerque.
A system of dams and tunnels known as the San Juan-Chama Project diverts water away from the San Juan River in the Navajo Reservoir area into the Rio Grande on the other side of the continental divide. The San Juan-Chama project can divert up to 96,000 acre-feet per year, but Williams said next year that full amount will likely not be available to augment the Rio Grande.
While irrigators that rely on the Rio Grande have been anxiously watching the dropping water levels that recently were bolstered by monsoon storms, the irrigators in San Juan County that rely on the San Juan River have not faced the same types of concerns.
“This year wasn’t that bad of a year up here, the snowpack was actually close to average,” Williams said.
But the drought-plagued Colorado River system means increasing scrutiny. Williams described it as being under a microscope.
Williams said the Office of the State Engineer is working toward what is known as depletion administration on the San Juan River. That means measuring how much water is diverted and how much is returned to the river to calculate how much water is actually being used.
The US Bureau of Reclamation gave the Colorado River basin states until the middle of this month to come up with a plan to reduce water usage for 2023 by two to four million acre feet. In July, the upper basin states submitted their plan, which does not include any mandatory water cuts.
Instead it relies on things like better measurement, monitoring and reporting infrastructure.
“The Upper Basin is naturally limited to the shrinking supply of the river and previous drought response actions are depleting upstream storage by 661,000 acre-feet,” the letter the Upper Basin states sent in July outlining the plan reads.
The previous response actions referenced include releasing water from storage in reservoirs like Flaming Gorge, which is located in Wyoming and Utah.
It won’t be this year, but Williams said someday in the future the San Juan River water users in New Mexico will face a situation when they will have to decide who gets to use water, something that has never happened before. This could be based on priority rights, meaning people who have older water rights get first dibs on the water. But Williams said it is more likely that the system currently used on the Animas River, a tributary of the San Juan, will be implemented. This system uses ditch rotation to ensure that every irrigator gets some water.
Williams said there are a lot of junior water users—or people whose water rights are more recent and thus subject to being cut off under priority administration—who rely on irrigation to farm.
Should it get to that point, people along the Rio Grande will also be impacted as the San Juan-Chama Project will take shortages before many of the water users in San Juan County.
Efficiency projects like irrigation ditches can help make the limited water go further by reducing the amount lost to vegetation and the soil.
“The problem is cost. Lining ditches with concrete or pipe is expensive,” Williams said.
He also encouraged water users to be as efficient as possible.
He said people in the San Juan Basin can only control their own water use.
“If everybody’s efficient there then we have to leave it to Mother Nature and then our office to administer when we do get short,” he said.
Williams said the Office of the State engineer was “given a hammer for administering the basin” and that the office tries to “use that hammer to be as soft as possible.”
The non-Native American water rights in the San Juan River basin were adjudicated in 1948 when San Juan County looked much different.
Williams said back then San Juan County was an agricultural area where produce was grown.
“That’s changed now. The crop types have changed. A lot of pasture and alfalfa. Very little vegetables at all. It’s all changed, so priorities have changed,” he said.
At the same time, farmland has been converted into residential areas.
The 1950s brought an oil and gas boom to Farmington and its surrounding communities, which also led to a change in water use as extraction requires water. But that, too, has changed, Williams said, as the fossil fuel industry has moved away from using fresh water in favor of produced water or deep saline aquifers.
Determining how much San Juan River water is available to use is a complicated process.
The US Bureau of Reclamation manages Navajo Reservoir, which straddles the New Mexico and Colorado state line and is one of the key Upper Colorado River Basin storage reservoirs.
Williams said there are two types of water in Navajo Reservoir—storage water and direct flow.
Direct flow water is based on the rivers flowing into the reservoir.
On Wednesday, the flows into Navajo Lake were 1,582 cubic feet per second while the dam was releasing 396 cubic feet per second. That means all of the water being released was direct flow water.
But, in mid-July, the amount of water released from the reservoir exceeded the amount entering.
That could mean storage water was being released, however Williams explained that agreements like the Navajo Water Settlement complicate that.
The Navajo settlement states that if on May 31 there is at least 1 million acre feet of water in Navajo Reservoir, then the water classified as direct flow cannot drop below 225 cubic feet per second regardless of how much water is actually entering the reservoir.
Williams said the Army Corps of Engineers and the Bureau of Reclamation had different numbers this year. The Corps’ calculations say that it met the requirements settlement; however, the Bureau of Reclamation’s calculations show the reservoir levels below 1 million acre feet of water.
That is not the only factor determining how much water is released. The Bureau of Reclamation is required to keep a certain amount of water—an average base flow of 500 to 1,000 cubic feet per second—in the San Juan River between Farmington and Lake Powell in order to protect endangered fish like the Colorado pikeminnow. Williams described this process as chasing a target baseflow downstream.
Water from storage can be released to protect the critical fish habitat.
Not all of that water in the critical habitat is coming from Navajo Reservoir. The Animas River joins the San Juan River in Farmington and provides some of the water needed to meet that average base flow requirement.
In the last 40 days, the lowest amount of water released from Navajo Reservoir was 381 cubic feet per second.