What a Difference a Year Makes on the Colorado

Water returns to Boulder Harbor on Lake Mead. But how long will it remain? (Photo: John Fleck)

By John Fleck

There’s five feet of snow now at Bison Lake, on Colorado’s west slope north of Glenwood Springs. Melted and measured by the folks who run the federal SNOTEL network, that translates to 15.6 inches of “snow water equivalent”, the metric that matters once spring and summer warmth start its trip down into the Colorado River.

The water nerds pronounce SWE as “swee”, a word that sounds vaguely like a ski move, but it’s really the most important number in western water right now, the measure of water supply for the year to come, sitting in the relatively small patch of high country that feeds the entire Colorado River Basin. Last year at this time, the SWE values at Bison Lake were nearly twice as high, and the bounty just kept building. This year things aren’t looking so good.

In December, I paid a visit to Boulder Harbor on the west shore of Lake Mead to see the results for myself. Boulder Harbor is one of those places where the dropping reservoir is made tangible. Two years ago, its boat ramp was closed, its shrinking harbor abandoned to an epic flock of American coots feasting on the critters left in the muck and an osprey that entertained me with a spectacular dive to pick off a stranded fish. Now, thanks to last year’s big snowpack, the water’s back, and boaters have displaced my osprey and coots.

But things appear to be headed back in the other direction. On its face, the effect is clear. After rising with last year’s big snowpack, Lake Mead and Lake Powell, the Colorado River’s two largest reservoirs, are forecast to drop a collective 42 feet in surface elevation over the next year, according to the latest forecast from the US Bureau of Reclamation.

But the while those results are in some sense obvious – reservoirs go up in a wet year and down in a dry one – there’s a subtler problem buried in the Bureau of Reclamation’s data. (Read more)

The formulas used under the “Law of the River” to divide the Colorado’s water between the Upper Basin and Lower Basin meant California, Arizona and Nevada got what amounts to “bonus water” in 2011 – a whopping 4.3 million acre feet above the legal requirement under the Colorado River Compact and related laws. But total storage in Lake Mead, where we’re supposed to be saving the water for a not-rainy day, went up just 2.9 million acre feet.  The problem, as Bureau of Reclamation hydrologist Paul Miller explains, is that the lower basin states are perpetually living beyond their means. They’ve come to depend on bonus water to meet their ongoing hydrologic expenses.

Thanks to some lingering water left over from last year in Lake Powell, held back until this year to maximize power generation at Glen Canyon Dam, the Lower Basin stands to get a bit of bonus water again this year. But the forecasts suggest they’ll have spent it all and then some by the time the year is over. 

Last modified Fri, 3 Aug, 2012 at 12:36