May showers bring better outlook for Colorado River, but no miracle

It wasn’t the “Miracle May” that some observers called it, but a month of downpours in Colorado and Utah did provide a significant boost to the outlook for the Colorado River.

A terrible year became merely below average.

“ ‘Miracle’ is probably a bit of an overstatement, but the unusually wet May did have a positive impact on water supply,” said Paul Miller, a senior hydrologist with the National Weather Service’s Colorado Basin River Forecast Center in Salt Lake City.

Just a month ago, federal forecasters expected to see the Colorado at about 42 percent of its average flow. The U.S. Bureau of Reclamation’s latest monthly forecast, unveiled Monday afternoon, has upped the projection to 70 percent of average for the river that fills Lake Mead and supplies 90 percent of the Las Vegas Valley’s drinking water.

The change represents an additional 2 million acre-feet of water flowing into Lake Powell on the Utah-Arizona border. That’s enough water to supply the entire Las Vegas Valley for almost nine years.

The new forecast is a big improvement, to be sure, but it’s not enough to avoid the 12th dry year on the Colorado since 2000.

“Not even close,” said Randy Julander, who supervises the U.S. Department of Agriculture’s snow survey program in Nevada, Utah and California. “May has been an outstanding month, but I would have much rather seen it in February. We have a little saying: Rain waters your lawn, but snow fills your reservoirs.”

And as you may have heard, the two largest reservoirs on the Colorado River are far from full. Lake Mead is at about 37 percent of capacity and Lake Powell is at 50 percent after 15 years of drought on the over-taxed river.

Even with the improved outlook, forecasters expect Lake Mead to stay below 40 percent of capacity for at least the next two years, though its surface should be high enough in January to comfortably avoid a federal shortage declaration that would force Nevada and Arizona to take less water from the river.

There probably won’t be a shortage the following year either, according to the new forecast.

The Bureau of Reclamation’s latest prediction calls for Lake Mead to start 2017 a few feet above the shortage line. That’s a major change from last month, when those same forecasters expected the lake to be about 18 feet lower and well into shortage territory in January 2017.

Throughout May and the first part of June, most of Colorado and parts of Utah saw record rainfall and some late-season snow at higher elevations. As of late last week, one watershed in southwestern Colorado boasted 8,000 percent more snow on the ground than usual for this time of year, though Julander called that more of a mathematical quirk than a drought-killing deluge.

“If you average 0.1 (inch of snow) and you get 1 (inch), that’s 1,000 percent of average,” he explained. “But one inch of snow can melt off in one day and be gone.”

At least the May showers were well timed, Julander said. They arrived just as farmers usually ramp up their use of irrigation water, essentially relieving about two months of strain on drought-stricken reservoirs and groundwater tables in Colorado and Utah, Julander said.

Experts agree that it will take more than a single good month for the river to recover and its reservoirs to refill. What’s really needed is a string of extremely wet winters like the one in 2012 that buried some parts of the basin under record snow.

But it’s too late for that this year.

“The snowmelt is pretty well over and done with,” Julander said.

The real miracle will have to wait until winter.

Contact Henry Brean at hbrean@reviewjournal.com or 702-383-0350. Find him on Twitter: @RefriedBrean