The Rio Grande gaging station near Del Norte has told the story of the river’s flow since 1889

By cvlopez | clopez@alamosacitizen.com

RIO GRANDE COUNTY ROAD 17

IT’S a commonly known spot off County Road 17 between Del Norte and South Fork. Driving in you might see a blue heron standing off in the marsh and river rafters looking to get onto the Rio Grande at the very spot Colorado has been measuring the river since the summer of 1889 – June 1, 1889, to be precise.

This time of year, with any ice on the river gone and the weather warming, Jessie Jaminet comes every two weeks to the stream gaging station operated by Colorado Division of Water Resources to make sure everything is functioning for measurements that are closely watched by water managers up and down the Rio Grande. He was there this past week to get an early spring reading and when prompted for a prediction on this year’s flows said, “I think we’re probably going to be slightly below average from what I’ve seen.”

Average over the past decade has been 491,000 acre-feet of water; historically going back to 1889 the Rio Grande has an average measurement of 639,000 acre-feet, according to figures maintained by the state.

Jaminet, lead hydrographer for state water resources division 3, cautions that the river “changes daily right now.” 

“Any storm that hits right now is a huge benefit for the whole system. People watch the snowpack numbers, but it really depends on what happens this time of year. Wet spring storms really benefit the system,” he said.

The Rio Grande gaging station near Del Norte is the highest profile gage station in the Upper Rio Grande Basin. That’s because it’s the gaging station the state uses to help determine how much water from the Rio Grande is available and will be delivered downstream into New Mexico and Texas as part of the three-state Rio Grande Compact.

Besides measuring lower-average acre-feet the past decade, another phenomenon has been occurring: an earlier peak to the river flow and then a quick dropoff, which means less water and shorter irrigation seasons downstream for New Mexico and Texas.

“Historically the river would peak and we would maintain those flows for a while before we would fall into base flow conditions,” Jaminet said. Peak flow used to hit mid- to late-June and the Rio Grande would maintain itself through the summer. Now the state is seeing peak Rio Grande flows as early as late May and then drastic drop offs to the height of the river. It’s attributable to the aridification of the Valley floor from persistent drought and climate change.

Colorado’s obligations under the Rio Grande Compact is another aspect to the management of the upper basin of the river that water managers, irrigators, and outdoor recreationalists have to factor in when planning their own water usage. 

“This is what we base pretty much all of our numbers on, this upper index here. Anything that passes this gage here we have to deliver a percentage of it downstream. This is why this is an important gage here,” said Jaminet.

He’s been working the measurements the past 15 years as part of his job with Colorado Division of Water Resources to operate and maintain the gaging stations along the Upper Rio Grande Basin. It’s not what he planned on doing for a career when he graduated from Mountain Valley High School in Saguache in 2001 and then the University of Wyoming, where he majored in rangeland geology and watershed management. But he’s learned and come to understand the importance of taking the river’s measurement, and the fact he grew up in the San Luis Valley makes him appreciate the work he does even more.

“This is a continuous record that we produce here,” he said of the Del Norte gaging station, pointing to the readings from 1890 through 2021. One of the most eye-popping historical figures is Oct. 5, 1911, when the Rio Grande was flowing at 18,000 cubic feet per second. The day Jaminet was at the gage station the river was moving at 519 cfs. 

Most of the big diversions to the Rio Grande happen a bit farther downstream in Rio Grande and Alamosa counties, making the gaging station near Del Norte a natural location to determine the depth and velocity of the river.

In the 1890s and early decades of the 1900s the state division of water resources would take a measurement of the Rio Grande twice a day and then daily as it kept improving the system. It eventually installed a continuous reader in 1983, and then in the summer of 1984 a satellite monitoring system was installed.

Now the gaging station takes a reading every 15 minutes and logs and transmits the data every hour to the Colorado Division of Water Resources website, where it’s tracked and followed by the three states party of the Rio Grande Compact. Fishermen and rafters will also monitor the web site to help them determine the best times to fish and float the river.

One of Jaminet’s responsibilities is to make sure the gaging station is calibrated and reading accurately. A float sitting in a stilling well reads the height of the river and then a rating table unique to the gaging station is applied to give an accurate measurement. In the winter months, with ice on the river, the measurements are more estimates.

Coming off a dry 2021, in January the Rio Grande was at its lowest point to start a year since Colorado began taking measurements 132 years ago. A cooler March and April have helped, but without significant summer rain, the Rio Grande will run dry again early in the summer irrigation season.

“If you go into the fall really dry, even if you get these big spring storms it seems like it just goes into the ground,” Jaminet said. “A lot of it is not making it to the river anymore.”

The measurements at the Rio Grande gaging station near Del Norte tell the story.