Alamosa never gets 16 inches of total precipitation in a year. Never. Ever. Except that it did in 2024.
Turns out, 2024 was among the wettest on record across the San Luis Valley going back to 1895, with all six counties registering historic levels of precipitation. Here are the precipitation totals by county, according to data from the NOAA National Centers for Environmental Information:
- Alamosa County, 16.75 inches
- Conejos County, 24.29 inches
- Costilla County, 22.53 inches
- Mineral County, 32.60 inches
- Rio Grande County, 19.66 inches
- Saguache County, 21.86 inches
The headscratching is how so much moisture was realized in a year when the unconfined aquifer of the Upper Rio Grande Basin dropped to near its lowest level, which became problematic for irrigators who are under orders by the state of Colorado to reduce their groundwater pumping to help recover the ailing aquifer.
“Two things,” said Cleave Simpson, general manager of the Rio Grande Water Conservation District and local hay grower. “We didn’t have continuous steady snowpack in the winter months that put us in a good position, and then the volume of snow we got was on top of drier conditions last fall where moisture, instead of showing up in a stream, ends up in the ground in soil conditions.
“So to that end, this year at my farm in October, I get an inch and a half of rain, in October. That never, ever happens. So the hope is then, that nice soil moisture that we got in October will set us up for success.”
Craig Cotten, division engineer for the Colorado Division of Water Resources, said the wet 2024 was a boon to local farmers and their efforts to recover the Valley’s aquifers. What it didn’t do was increase the amount of water stored in reservoirs.
“The reservoirs in the Rio Grande Basin in Colorado typically store water in winter when the senior priority ditches are shut off. The reservoirs can also store during the irrigation season, but only if there is a significant amount of water in the rivers to serve not only the irrigation ditches but the reservoirs as well,” said Cotten.
“This typically requires very high river flows, which did not occur in 2024 even with the rain events that were the primary reason for the high precipitation total in 2024. The significant rains in the Rio Grande Basin did increase the river flows, but not enough to get the reservoirs into priority. The increase in reservoir storage in 2024 was about typical of what occurs in an average year.”
Without the high levels of precipitation in 2024, the critical unconfined aquifer was in danger of falling to a level of storage nobody was expecting to see after years of irrigators working to reduce their groundwater pumping.
“The large amount of precipitation in the Rio Grande Basin during the summer of 2024 helped the unconfined aquifer in multiple ways,” said Cotten. “This precipitation increased the streamflow in the Rio Grande throughout the summer, allowing the ditches and canals to divert more water than they otherwise would have.
“This increased diversion in turn allowed delivery of a higher amount of water into recharge pits and the aquifer. The precipitation also helped to meet the irrigation needs of the crops, allowing the farmers to not pump their wells as much as they would otherwise.”
The hope among local farmers is that the wet fall months of 2024, when October and November delivered more than 11 inches of snow, will translate into an above-average spring runoff and give a boost to surface water coming into the Valley in 2025.