Warm, dry year breaks records in the Yampa River Basin
October 20, 2018
STEAMBOAT SPRINGS — Each spring, the snow that piles up in the Flat Tops, Elkhead and Park mountains melts off, making the Yampa River swell with runoff water.
Some of that water is captured in local reservoirs, but what isn't captured makes its way downstream into the Green and then Colorado rivers, irrigating hay meadows, helping generate power and providing habitat for plants and wildlife and recreation for river rats along the way.
When the snow melts, the river recharges through rainfall and reservoir releases.
This cycle of snow, swell and streamflows make up a water year.
The past water year, which began in October 2017 and ended in September, broke records on the Yampa. Average temperatures in much of the Yampa River basin were the warmest on record, and for the first time ever, the main stem of the Yampa River was placed on call, meaning use of Yampa water was curtailed.
This summer, the portion of the Yampa River in Steamboat Springs city limits was open to summer recreation — including tubing, fishing and paddling — for about 40 days, one of the shortest summer seasons on this stretch of river. For much of the summer, the river was under a voluntary closure as the water was too hot, too low or without enough dissolved oxygen to meet streamflow standards set by the city and Colorado Parks and Wildlife to protect river habitat.
Warm and dry summer
The Yampa and Colorado rivers peaked in mid-May, and according to long-term averages of daily flows, both rivers normally peak in June. This led to the second earliest start to tubing season on the Yampa in 10 years.
A warm spring played a role in this — as snow melted off the mountains earlier, water flowed downhill into the river and its tributaries earlier. This water year was the warmest on record in the state, according to the Colorado Climate Center.
In Routt County, about half of the county saw its warmest water year on record, while parts of central and south Routt saw temperatures in ranges that placed it among the top 10 percent of the record.
Most of Routt County received below normal precipitation this year, though the area fared better than other parts of Colorado. The National Weather and Climate Center's snow telemetry sites in the Routt County area received 70 to 80 percent of average precipitation this year, though July, August and September saw lower rainfall compared to historic averages.
"Statewide, this was the fourth driest year in the 123-year record,” said Kelly Romero-Heaney, water resources manager for the city of Steamboat Springs. "It was fourth only to 2012, 1934 and 2002."
This year was the driest water year on record in southwest Colorado, western Moffat County and parts of the San Luis Valley, according to the Colorado Climate Center.
Human-caused temperature increases and drought have caused earlier spring snowmelt and shifted runoff earlier in the year across the southwest, according to the 2014 National Climate Assessment.
"Not only are we in situations where we get less water, but we get it earlier, which makes for a longer season of need," said Kevin McBride, district manager of the Upper Yampa Water Conservancy District.
His agency operates Stagecoach and Yamcolo reservoirs.
The early runoff means producers kicked off the irrigation season earlier, too. Producers are also seeing longer growing seasons in Colorado, according to the U.S. Environmental Protection Agency.
Reservoir water keeps flows up
Drought conditions and warm temperatures have made supplementing the Yampa River's natural flow with releases of reservoir water a consistent practice in recent years.
Since 2012, the Colorado Water Trust has purchased reservoir water to supplement flows in the Yampa River. This year, Tri-State Generation and Transmission also released water from Elkhead Reservoir to keep up power generation at Craig Station.
The Upper Colorado River Endangered Fish Recovery Program releases water from Elkhead Reservoir to provide habitat for bonytail, razorback suckers and humpback chum. These releases are determined based on the amount of water flowing by the U.S. Geological Survey's stream gauge near Maybell in western Moffat County.
"Obviously, when you have low flow years, you have warmer stream temperatures and then less habitat available to aquatic life," Romero-Heaney said.
In Steamboat, the river dropped to 50 cubic feet per second — low flow — during spawning season for brown trout, she added. That made habitat more difficult to come by, and Romero-Heaney said it could have impacts to fish populations in the upper Yampa.
The Yampa Valley suffered major droughts in 2002 and 2012. In 2002, the USGS reported less than 10 cubic feet per second of flow at the Maybell gauge at the Yampa River's lowest points in the summer, said Erin Light, area division engineer for the Colorado Division of Water Resources.
Reservoir releases likely kept the water higher than that mark this summer. The USGS streamflow gauges can’t show how much water is natural flow and how much is reservoir water, so stream gauge measurements don't reflect the full picture when it comes to water.
"To the person that's just looking at the river, they're thinking ‘Oh, this isn't as bad as 2002 or maybe not as bad as 2012,'" Light said. "You're not comparing apples to apples. You have to think about how much reservoir water is in the river.
"No doubt, this year the Maybell gauge dropped down — I think even at one point there was really no natural flow left or very minimal natural flow," she said. "So we can imagine that scenario if that reservoir water wasn’t there. It would probably be close to 2002 levels."
When the call was administered for about two weeks in September, the water at the Yampa's lower reach through Dinosaur National Monument fell to about 18 cfs — its long-term average for the same time frame is about 260 cfs. At Lily Park, near the Little Snake River's confluence with the Yampa, irrigators' pumps were sweeping the river, Light said earlier this year.
Planning for the future
Romero-Heaney said flows on the Yampa in Steamboat were “extremely low,” falling below 34 cfs at the gauge at the Fifth Street Bridge in Steamboat.
"That is extremely low, and it was unexpected, especially given our snowpack year, which was still mediocre, but not horrible," she said.
"It's the extremes that get you," McBride said. "The extremes are what we are trying to plan for."
Researchers have used tree ring data to understand about 500 years' worth of streamflows in the Upper Colorado River Basin. Some long, dry times are in that record, McBride said, but now, there is the added “wildcard” of rising global temperatures. McBride believes more stored water in reservoirs is the path forward.
The city outlined its plans to purchase reservoir water on contract to boost flows in dry periods in the Yampa River Streamflow Management Plan released this summer. The plan also seeks to implement voluntary projects that would pay water users to participate in projects enhancing the health of the river.
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Earlier this year, some of the city's water rights were curtailed in the call. As droughts and warm temperatures become more common, releases to augment river health will likely have to be balanced with releases to augment municipal water.
"We developed a stream management plan to prepare the community and the river for years like this, so as we move forward implementing that, our hope is that our system will be more resilient to drought years like this and like 2012 and 2002," Romero-Heaney said. "If it happened this year, we know it can happen again."