SNOWPACK IN THE ROCKIES
Nothing against California, you understand. We’re all delighted to hear about this winter’s bounty of rain and snow, especially as it piles high in the Sierra Nevada.
Love all those “atmospheric rivers.”
It is great to hear of expert-level debates over whether the Golden State’s drought designations should be eased -- or even lifted entirely -- especially in the north of the state.
There are parts of the mountains immediately east of Sacramento and San Francisco that have experienced well over 200 percent of the official average precipitation. As they say in southern Cal: Whoa!
But, well… it’s not all about California, you know.
According to data compiled and analyzed by the National Water and Climate Center, precipitation thus far in the “water year” – that is, the period beginning October 1, 2016 – has been predominately “near to well above average” almost everywhere in the West, except Alaska.
Meanwhile, the snowpack in the southern regions of the Western U.S. – the areas of the West most seriously impacted by record and near-record drought – is being judged “well above average,” according to the results reported in the Water and Climate Center’s Snow Telemetry (SNOTEL) summaries.
That snowpack translates, ultimately, into the statistics that matter most to the 35 million-odd people living in the Colorado River basin: the streamflow forecasts and the expectations for reservoir storage levels. And those are looking better than they have in a long time too:
The SNOTEL measurements depict “well above average streamflow in the middle and southern parts of the West,” and reservoir storage amounts that should be “above average in Montana and Wyoming, near average in Colorado and Nevada.”
As of February 1, the Center is forecasting inflows into Lake Powell at 147 percent of the 30-year average for April through July, a critical streamflow period.
For Arizona specifically, the precipitation picture has brightened considerably this winter.
“We have to go all the way back to 2010 the last time we filled the reservoirs,” said Salt River Project water operations manager Charlie Ester to 12News on February 2.
“In the seven years since then, we have progressively lowered the reservoirs to the current conditions.”
With much of Arizona’s water supply beginning its annual journey on the western slopes of the Colorado Rockies, the Water and Climate Center’s early February report is promising. January produced 217 percent of normal precipitation in Colorado, and the February 1 snowpack is at 156 percent of normal, up 43 percent from January.
As a result, streamflow forecasts “are nearly all above normal with the western basin projections providing the highest forecasts,” according to the Water and Climate Center report.
Even in the best of times, precipitation never distributes evenly.
As of February 1, the “snow-water equivalent levels” – that is, the amount of liquid, flowing water expected to be produced from a region’s snowpack – range from 88 percent of median in the San Francisco-Upper Gila River Basin to 166 percent of median in the Verde River Basin.
Still: “Cumulative precipitation since October 1 is now well above normal in all major river basins for the water year.”
Precipitation disclaimers in the arid Southwest are always lit bright, however. The remarkable measurements of the winter to date are entirely capable of petering out to nil. Which is a pretty good summary of how last winter went.
A winter’s precipitation is the result of weather. And while drought is a function of weather over time, it isn’t something that disappears in a single, wet season.
The effects of drought, for example, can be cumulative. The volume of Southwestern desert dust that blows east onto the western slopes of the Rockies has been shown to have a cumulative effect on the duration of the winter season.
NOAA’s Cooperative Institute for Research and Environmental Sciences at the University of Colorado Boulder, for example, reported in late 2013 that the snowpack of the Rockies “is melting out as many as six weeks earlier than it did in the 1800s,” as a result of a thick layer of desert dust.
It’s not just drought that impacts Colorado River streamflow, in other words.
Moisture at these levels in the West can make people forget quickly the long-term issues the region faces. Already, Californians are in a fierce debate over whether to extend Gov. Jerry Brown’s emergency drought declaration and whether or not to ease up on other water-conservation efforts.
“Most water agencies have yet to adjust to this ‘new normal’ and are operating on outmoded assumptions and practices that place the state at risk of water shortages and worse,” argued climate-change expert Alex Hall of UCLA in a commentary that appeared February 5 in the Los Angeles Times.
Hall’s concern – that the recent snow and rain will blunt efforts to improve water-use efficiencies in southern California – is a concern for the entire Southwest.
Could this one year’s abundance blunt efforts to resolve the systemic over-allocation of Colorado River water, for example?
If there is a downside to the current – and literal – flood of moisture into the region, it is that.
“While I’m happy about all the snow,” said Water Resources Director Tom Buschatzke, “we don’t have enough certainty about what Mother Nature is going to send us.
“We have to focus on what we have control of.”