By Sarah Maxwell, NRCS
March streamflow forecasts show a decline in nearly every Western state and basin, according to water and climate experts.
USDA’s Natural Resources Conservation Service National Water and Climate Center hydrologists predict dry conditions to continue from the less-than-average precipitation during February, which indicates reduced spring and summer water supply for much of the West.
"With only one month remaining in the snow season, it’s highly unlikely the snowpack will recover to normal levels over the Four Corner States," hydrologist Tom Perkins said.
Although other parts of the country got more snow, it didn’t have impact in the western mountains, he said.
"What fell in the West didn’t really amount to much," Perkins said. "New Mexico, Utah and Colorado are especially vulnerable, because their reservoirs are at low levels due to sustained drought conditions."
At this point, it looks like water supply conditions will end up below average for most of the West’s rivers. Water resource managers will need to make some difficult decisions in the coming months due to this shortage, Perkins said.
There are a few exceptions to the dry forecasts. Spring and summer streamflow forecasts as of March 1, are calling for near normal levels across Oregon, Washington, Idaho and western Montana. Below normal flows are predicted over the rest of the Western U.S.
Although some are at normal levels now, March 1 snowmelt runoff forecasts trends indicated worsening conditions as compared to the Feb. 1 report. Forecasts decreased 5 to 10 percent in Washington and Oregon; 10 to 20 percent in Montana, Idaho and Utah; 10 to 15 percent in Colorado. Forecasts increased 5 to 10 percent in north-central New Mexico, but this was not enough to make up the shortfall.
"Although NRCS’ streamflow forecasts do not directly predict drought, they provide valuable information about future water supply in states where snowmelt accounts for as much as 50 to 80 percent of seasonal runoff," according to Perkins.
In addition to precipitation, streamflow in the West consists largely of accumulated mountain snow that melts and flows into streams as temperatures warm into spring and summer.
The March forecast is the third of six monthly forecasts issued each year between January and June by the national center. The forecast compares the current level of water content in snowpack in the 12 Western states with historical data to help the region’s farmers, ranchers, water managers, communities and other stakeholders make informed decisions about water use and future availability.