Hydrologists cautiously optimistic about Colorado River Basin flows after a wetter than normal El Nino season | TheFencePost.com

Hydrologists cautiously optimistic about Colorado River Basin flows after a wetter than normal El Nino season

Amy G. Hadachek
for The Fence Post
This is our latest "forecast evolution plot" for Lake Powell. This plot shows how our forecasts have evolved since mid-December. You can see that initially we were forecasting below average conditions, but by the time March came around, we were forecasting near normal conditions. Then, as the wet conditions in March really got going, our forecast increased accordingly. Some parts of the basin have been relatively dry since the middle or end of March, and you can see that our forecast has leveled out, and even decreased slightly, since then.

Cautiously optimistic about the Colorado River Basin which is now trending in the right direction after this wetter than normal El Niño winter/early spring, hydrologists, however, say there’s still considerable ground to make up after 19 consecutive years of historic drought.

That was the key message during a live webinar on April 24. Although the 2018 exceptional drought strained the Colorado River Basin, that drought was followed by heavy 2018-2019 winter snowpack which has a direct impact on basin conditions, and the Colorado River Water Supply as well as critical reservoir operations including Lake Mead and Lake Powell.

The webinar was a joint project of National Oceanic and Atmospheric Administration’s National Integrated Drought Information System, NOAA’s Colorado Basin River Forecast Center. NOAA’s National Weather Service, the Bureau of Reclamation, U.S. Department of Agriculture, state climatologists, universities and other drought experts.

“This year has been wetter than normal over the Colorado River Basin, particularly in the significant, high elevation areas that accumulate most of the snowpack, which results in runoff during spring. The first two weeks of March were exceptionally wet in the western half of Colorado, where there are many SNOTEL stations (SNOTEL is: Snowpack telemetry weather stations that monitor snowpack accumulations.) These SNOTEL stations reported that precipitation was the wettest, or among the wettest, on record,” said Paul Miller, service coordination hydrologist for NOAA Colorado Basin River Forecast Center in Salt Lake City, Utah.

In the Upper Colorado River Basin, precipitation so far this year is well above average throughout Colorado and central Utah, and near average in the northern portion of the basin in southern Wyoming. “These areas contribute significantly to our seasonal runoff, and this year appears to be a beneficial one for many water resource managers in the basin,” Miller said.

Impressively, these spring runoff forecasts are about 120 percent of normal. The most widely known areas reporting the highest runoff are the flows into Lake Powell at the Glen Canyon Dam, which is forecast to be 128 percent of normal. The Gunnison River near Grand Junction, Colo., is at 135 percent of average. The San Juan River near Bluff, Utah, is at 125 percent of average.

“This is all good news,” Miller said. “For us it’s always exciting because regardless of the water condition in the basin, there are always interesting things going on with the way people are managing water resources. For instance, people are trying to meet higher environmental flow targets and using our data more, like state water agencies (including Denver Water and the Central Utah Water Conservation District) and federal agencies like the Bureau of Reclamation.”

Miller said that the Bureau of Reclamation manages the largest reservoirs in the Colorado River Basin, like Blue Mesa Reservoir, Lake Powell and Glen Canyon Dam, Flaming Gorge Reservoir and Hoover Dam and Lake Mead, and help distribute the water supply to the seven basin states (Wyoming, Utah, Colorado, New Mexico, Nevada, Arizona and California) and Mexico.

“While we are pleased to see the above average snowpack conditions in the Upper Basin and the improvement in the inflow forecast which may lessen the chance of shortage in 2020, we are reminded that one near- or above-average year will not end the ongoing extended drought experienced in the Colorado River Basin, nor is it likely to substantially reduce the current risk facing the basin,” said the U.S. Bureau of Reclamation Lower Colorado Region, in a statement.

DRIEST ON RECORD

The period ranging from 2000 through 2018 was the driest 19-year period in more than 100 years of recordkeeping, and that inflow into Lake Powell was below average 15 of the 19 years during the period from 2000 through 2018. Inflow into Lake Powell in water year 2018 (a water year is a calendar year from Oct. 1 of the previous year to September 30) was the fifth lowest on record. Colorado River System storage decreased from 55 to 47 percent of capacity in 2018.

Officials said it’s not unusual to have a few years of above average inflow during longer-term droughts. Water year 2011 was one of the wettest years on record, followed by two years (2012 and 2013) that were two of the driest years on record. As a result of persistent drought, Colorado River system reservoirs have declined significantly, and current system storage, as of April 23, 2019, is 45 percent of capacity.

The combined storage of Lake Powell and Lake Mead is at the same level it was in 1969, when Lake Powell was initially filling. In July 2016, the water level at Lake Mead declined to elevation 1,071.6 feet, its lowest level since initially filling in the 1930s.

When people discuss the word drought in the Colorado River Basin, officials said it’s always a tricky topic because it depends on who you’re asking and when.

“Despite this being a really good year and above average, water levels at many reservoirs are still very low, so we still need to continue to manage water resources efficiently and effectively,” Miller said. “Some will say they’re getting enough water to manage crops and things are good this year, and they kind of operate year by year. If you’re talking to someone at the Bureau of Reclamation or the Southern Nevada Water Authority, who depend on getting water out of Lake Mead, the water is low and they depend on those resources.”

Miller said some states are being proactive in providing incentives to people to manage water more efficiently and investing in infrastructure to manage resources.

Interestingly, the Colorado Basin reportedly is the most legislated basin in the world, and there’s new information being released often, about the basin.

The purpose and goal of the Colorado Basin River Forecast Center is to develop a multitude of streamflow products and services to help water resource managers, like the Bureau of Reclamation, they make important decisions regarding the operation of their reservoirs. “Our forecasts can also help irrigators, recreational officials and others make informed decisions regarding their activities and interests,” Miller said. “The CBRFC produces this information regardless of whether we’re in drought or not, so that we can always help stakeholders make the most informed decisions possible.”

The webinar was recorded and is available on: drought.gov. ❖

— Hadachek is a freelance writer who lives on a farm with her husband in north central Kansas and is also a meteorologist and storm chaser. She can be reached at rotatingstorm2004@yahoo.com.