America is certainly suffering the effects of flooding this spring and while we have no large-scale disaster such as that currently plaguing the Mississippi Valley, the West has its own flooding problems. As I look out my window at the Bitterroot Mountains I see a solid mantle of white, a scene more likely noted in March rather than May. After a cold, wet spring that inhibited the melting of that snow and even added to it, the Salmon River has finally risen with runoff.
The West has experienced a decade of "precipitation deficits," if not outright drought, so this past winter saw an embarrassment of riches for skiers and other winter recreationists. Snowpacks in the Northern Rockies, Pacific Northwest, and the Sierra Nevada in California are running 150-200% of average. Here where I live in Idaho, the Salmon Basin is 155% of normal, which is actually a low number. Farther south, the Portneuf River Basin above Pocatello sports an amazing 286%. These numbers promise at least minor flooding regionwide. But if the weather suddenly gets hot or rainy, it will be disastrous.
According to a recent story by AP, climatologists are pointing to this year's strong "La Niña," in which cooler water in the Equatorial Pacific Ocean causes wetter-than-normal winters in the Pacific Northwest, California, and Northern Rockies, and drier conditions in the Southwest. New Mexico, for instance, is suffering an early fire season with over 300,000 acres already scorched. The snowpack there along the Rio Grande is only 72% of average.
The numbers are extraordinary. Loveland Ski Area west of Denver broke its annual snowfall record of 572 inches (49 feet) set in the winter of 1995-'96. Snowbird Ski Resort near Salt Lake City also broke its own record with a massive 711 inches (as of three weeks ago), which is 59 feet. AP tells us that the resort plans to remain open until July 4.
The latter indicates huge snowpacks averaging over 200% along Utah's Wasatch Front, which spells flooding woes for metropolitan Salt Lake City. These snowpacks are even higher than those seen in 1983 when City Creek flooded parts of downtown. Interstate 80 was closed and the Great Salt Lake lapped at the runways of Salt Lake International Airport. This year sandbagging has been done earlier throughout the area.
The snowmelt in the Colorado River this year has caused the U.S. Bureau of Reclamation (BuRec) to release 3.3 million acre-feet of water from Lake Powell to Lake Mead, thus raising it 23 feet. That flow itself is 14 times the amount of water used in Las Vegas last year. Metro Las Vegas was in a drought with impending water restrictions as recently as last fall. "I'm delighted, absolutely delighted," Southern Nevada Water Authority general manager Patricia Mulroy told AP. BuRec is draining reservoirs throughout the West, as it seeks to move "storage" from one to the next to better handle the snowmelt. Palisades Reservoir sits at a mere 11% of capacity after water was sent downstream to other Snake River reservoirs in anticipation of the big snowmelt soon coming from the upper Snake drainage, notably Wyoming's Teton Range and the southern reaches of Yellowstone National Park.
The major problem regionwide is that a cold April has passed without snowmelt. Usually about 25% of the snowpack melts before May 1, but not this year. This means that a substantial warmup, or what meteorologists euphemistically call a "rain event," could trigger disastrous flooding, degrees of which are inevitable. In Montana, for instance, the last big flood year was 1997, when the Yellowstone River (the last great undammed Western river) inundated parts of Livingston and other towns downstream. That scenario is likely again this year. Already the Yaak River in northwest Montana, the Clark Fork downstream from Missoula, and the Bitterroot River flowing from the south through its eponymous valley toward Missoula are at flood stage.
In California the Sierra Nevada snowpack is so bountiful that Central Valley Project irrigators will have 35% more water available to them this year than last. The snowpacks average 159% down to 127% north to south along the mountain range. The higher peaks around Lake Tahoe accumulated over 60 feet this past winter. Again, a fast warmup could inundate valley towns as in flood years past.
The West doesn't flood on the scale of the South. And considering that ongoing aridity is our normal state of nature, we'll take the bad with the good. It'll be a nice green summer.
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