Did You Miss It? Spring Runoff 2025

Pagosa Peak on 4/20/25

Spring runoff is underway! Or is it already over? The San Juan River hit a season high of 671 cfs just after midnight on April 13th. But that was before our abrupt return to winter last weekend. On April 19th, my yard had more snow on the ground than most of our "snowy" months! Thankfully, the recent snow and associated cold temperatures have extended our meager snowpack a little longer.

Late season snowstorm on 4/19/25

The Upper San Juan SNOTEL site peaked with 12.8 inches of water in the snow on 3/21, the 2nd lowest peak since 1979 (2002 peaked at 10.7 inches on 3/27). To provide a greater historical precedent, we can extend the period of record back to 1936 using snow course data. April 1st snow course measurements have been collected since 1936 along a transect adjacent to the site. Based on 90 years of data, 2025 had the 3rd lowest April 1st snowpack behind 1977 and 2002. 

Before the April 19th storm, the SWE at the Upper San Juan site (10140 feet) dwindled to 5.8 inches. Fortunately, the late snowstorm replenished another 1.2 inches of SWE. At the time of this writing, 5.2 inches of water remain in the 15-inch snowpack, which is better than 2002 and 2018. The Wolf Creek Summit SNOTEL site (10,900 feet) still has about 15 inches of water remaining in the 41-inch snowpack. The remainder of our runoff will be generated from this high-elevation snowpack.

As of 4/24, the 2025 snow water equivalent is 20% of normal.

In 2002, the San Juan River peaked at a measly 296 cfs on April 15, and the site was snow-free April 21st! At this point, the streamflow on the San Juan River has exceeded the peak flows in 2002 and 1977, but I don't expect the 2025 peak flow to surpass the 2018 peak. Notice how the historical average dwarfs all three of the years plotted below.

Peak spring runoff generated from years with lower snowpack.

Since 2018, I’ve attempted to predict the magnitude and timing of the peak runoff on the San Juan River using the peak SWE from the Upper San Juan SNOTEL site. Using only the peak SWE from one physical location is bad science because snow can vary dramatically from one sub-watershed to the next, and factors such as air temperature, antecedent soil moisture, sublimation, and dust on snow are other important factors that I ignore. But it’s a fun challenge nonetheless. Based on 89 years of record, my snow-flow prediction model forecasts a peak flow of 1130 cfs on 5/11/25. For context, the San Juan River peaks around 2500 cfs on May 25th.   

Some good news is that the stock ponds in the Turkey Springs area are full, which indicates the soil moisture is in decent shape (unlike our most recent drought in 2018). When the soil moisture is high, more snowmelt reaches the river instead of soaking into parched ground. Also, our dust-on-snow conditions are low, meaning the snowmelt won't accelerate due to a dark surface layer of wind-blown dirt (A Little Dirt Never Hurt...Right?).

The snowfields on our prominent peaks are a low-tech way to gauge the timing of the peak runoff. The snowfield on Pagosa Peak is shockingly low (as it was all winter). In fact, the snowpack has already melted at the Weminuche Creek SNOTEL station (10,730 feet), which monitors the snowpack in the Piedra River watershed.

Comparing the snowfield on Pagosa Peak: 4/11/25, 5/1/23, 5/1/18

Before last weekend’s storm, the geese on Quartz Ridge were nearly visible, and cutthroat was beginning to take shape on Blackhead Peak. Local lore says the spring runoff will recede when the geese are fully visible and the cutthroat jumps out of the snowfield beneath it. Both snow field shapes indicate that the peak flow has yet to occur.   

Snowfields on the Eastern Range on 4/16/25 (click here to read about the geese and cutthroat)

I was pleasantly surprised to see that the NWS is forecasting a chance of snow on Wolf Creek Pass almost every day through next weekend! Then, the long-range forecast shows the temperature bouncing back into the mid-70s in Pagosa Springs.  Assuming the weather forecast is reasonably correct, I think the river will peak at 1000 cfs on May 8th. Let’s hope I’m wrong and the upcoming stormy weather pattern extends our spring runoff event and reduces our wildfire risk. It's important to be prepared since our area has a high probability of burning. Even though I'm ready for summer, we need to delay summertime temperatures as long as possible, given our fire risk.

Burn Probability (Colorado State Forest Service).