The West may experience a lengthy runoff in 2019
While it’s always tricky making May or June runoff predictions in March, Snotel data from around the West indicates that snowpack levels, especially in Southern Colorado, Southern Utah, and parts of California’s Central Sierras, are poised in 2019 to create high flows or a long runoff season or both. Snotels—short for snow telemetry—are automated devices set up by the Natural Resources Conservation Service (NRCS) at various locations and elevations throughout 11 western states to assist water managers in making predictions about runoff, reservoir levels, and potential flooding. There are currently more than 700 Snotel sites scattered across mostly high-alpine watersheds. If you’ve been on a high-elevation hike and seen what looks like an oversized pillow off in the woods—that’s a Snotel. These pillows have pressure sensors; they don’t really measure snow as much as they measure water content in the snow.
Hopefully, the 50-year-floods taking place in Nebraska and Iowa as this issue goes to press are not indicative of what’s coming later for states on the other side of the Divide. All this snowpack might produce a nice extended float-fishing season for Western outfitters, but it also could put added pressure on popular tailwaters like the Madison, Green, Bighorn, or San Juan, as anglers go searching for clear water from late April through June.
Snow levels throughout the West remained moderate for most of December and January, but with the exception of western Washington and parts of northwest Montana, all of that changed in February. Record or near-record snowfall fell from Oregon’s Cascade Range to the San Juans of Colorado, with several basins sitting at more than 150 percent of average by mid-March. Jackson, Wyoming, experienced its snowiest February ever, getting more than 43 inches. And just to the northwest, in Island Park, Idaho—home of the Henry’s Fork—more than 105 inches of snow fell in February alone, breaking the previous record by more than two feet.
Montana also got pounded in February, with the month producing 180 percent of average precipitation. While the Flathead and Kootenai Basins in the northern part of the state were still below average by St. Patrick’s Day, most of the rest of the state was above normal, led by the Madison River Basin in the fishy southwest corner, with a snowpack at 130 percent of average.
The good news for California and Colorado is that, by mid-March, both the Upper Colorado River Basin and much of the Sierra Nevada were at more than 140 percent of average, feeding many thirsty reservoirs in both states. April 1 generally marks the high point of the Sierra snowpack, with spring runoff beginning shortly thereafter. As for runoff elsewhere, if your favorite freestone is too brown or burly in May, then I guess we’ll see you below the dam.