“Not a great year,” is how Colorado Division of Water Resources Division 3 Engineer Craig Cotten summed up the flows on Rio Grande and Conejos River systems this water year which ended Nov. 1.

The Rio Grande had an estimated annual flow of 485,000 acre-feet or 78 percent of the long-term average, while the Conejos River had 238,000 acre-feet or 79 percent of the long-term average, according to figures Cotten presented this week to Rio Grande Basin Roundtable members.

Under the Rio Grande Compact with New Mexico and Texas, Colorado will be obligated to deliver an estimated 122,500 acre-feet from the Rio Grande and 67,800 acre-feet from Conejos River downstream into New Mexico and its storage at Elephant Butte Reservoir.

“We are delivering all the water we have in the system to the state line,” Cotten said, noting that with the water year now ended there is 100 percent curtailment on the Rio Grande and Conejos River systems.

Getting into the fine details of the Rio Grande Compact, Cotten said Colorado is not storing any water from this year at Platoro Reservoir in Conejos County due to Article 7 of the compact. Platoro Reservoir is a post-compact storage reservoir which Colorado can’t utilize this year because storage of a usable water supply at Elephant Butte and Caballo Reservoir in New Mexico has potentially dropped below 400,000 acre-feet.

“Article 7 of the Compact is in effect and that restricts our ability to store in post-compact reservoirs. So we are not currently storing additional water in Platoro Reservoir,” he said.

The irrigation or water season in the Valley typically runs from April 1 to Nov. 1 and is primarily reliant on snow runoffs in the springtime from the surrounding San Juan and Sangre de Cristo ranges. The runoffs feed into the creeks and streams that come together to form the Rio Grande.

A lack of consistency in snowfalls over the past two decades and the warming of the southern end of Colorado compared to the state’s northern frontiers has San Luis Valley irrigators constantly working to figure out how to farm and ranch in a climate of aridification.

“The forecast is for the northern areas to get more snow than the southern areas,” Cotten said in looking at the outlook for 2024-25 winter.

The Colorado Climate Center, at the start of 2024, released a study showing how “the greatest warming has been observed over the Southwest and San Luis Valley climate regions.”