STEAMBOAT SPRINGS — The city of Steamboat Springs is exploring a way to help it stay in compliance with state regulations and also cool down chronically high temperatures in an impaired stretch of the Yampa River.
A program called water-quality trading could allow the city to meet the requirements of its wastewater-treatment facility’s discharge permit from the Colorado Department of Public Health and Environment by cooling other areas of the river by planting trees.
The Yampa River flows through downtown Steamboat, where several parks and the Core Trail have been built along its banks. The river, a vital and cherished amenity for the Steamboat community, is popular with tubers and anglers. According to a 2017 survey of citizens, 75% of respondents ranked the management and health of the Yampa as essential or very important.
But low flows and high temperatures, made worse in recent years by climate change, have impacted the public’s ability to use one of their favorite amenities. In July, the city closed the river to commercial use because of high temperatures — over 75 degrees. The city also recommended a voluntary closure for noncommercial users of the river.
The entire 57-mile segment of the Yampa from above the confluence with Oak Creek to above the confluence with Elkhead Creek often has temperatures that are too high during the summer months, and in 2016 the segment was designated as impaired for temperature under the Clean Water Act. For July, August, September and November, stream temperatures exceed state standards for a cold-water fishery.
Because the river is classified as impaired, city officials expect that when CDPHE issues a future discharge permit for the city’s wastewater-treatment plant, it will include more-stringent water temperature standards. The wastewater-treatment plant may not be able to meet these standards unless it cools the effluent before releasing it back into the river. The city’s current discharge permit expires at the end of the year.
According to CDPHE Marketing and Communications Specialist Eric Garcia, Steamboat’s next permit will likely not have temperature limits, but will have temperature monitoring requirements. The soonest the city would have temperature limits for the wastewater treatment plan is Jan. 1, 2027.
“These monitoring requirements are included so that we have a full understanding of the temperature issues in the Yampa River and at the plant before we set any temperature limits,” Garcia said in an email.
But just cooling the effluent won’t fix the temperature problems on the entire 57-mile stretch. The wastewater-treatment facility is not the cause of the high temperatures — an engineering study could not pinpoint an exact cause, and the plant is 12 miles downstream from the start of the impaired section — and city officials see an opportunity to improve the health of the Yampa on a holistic, watershed level. Instead of just cooling the water at the plant, the city hopes to use a program of cooling whole stretches of the river by planting more trees.
“Of course, building a cooling tower will help us meet our permit limit, but it won’t help solve the stream-temperature problem,” said Michelle Carr, water distribution and collection manager for the city. “It would go against what we are trying to achieve in the watershed entirely.”
Steamboat has been working with The Freshwater Trust, an Oregon-based group, to explore what a water-quality trading program could look like. The Freshwater Trust assessed 119 miles of local streams and found 794 acres where riparian plantings could work at a potential program cost of $1.5 million.
According to David Primozich, vice president at The Freshwater Trust, the vast majority of heat in the river comes from the sun, so providing shade is an effective way to keep stream temperatures from rising. Over the decades, development and agriculture operations along the Yampa have removed riverbank vegetation, especially narrowleaf cottonwoods. Replanting these big, shady trees, which can top at least 60 feet at maturity, can help.
Using a modeling tool called the Shade-a-lator, The Freshwater Trust can determine the potential reduction in solar loading as a result of revegetation projects. By quantifying the benefits of restoring a river’s ecosystem, a water-quality trading program can create a path for the city to comply with temperature regulations.
“We found a way to convert the outcomes we know the environment needs into units that people can buy because they have to as a result of regulatory compliance,” Primozich said. “(The city) doesn’t want to spend money on things that don’t help the environment. They want a clean and healthy river.”
A June report from Englewood-based Jacobs Engineering looked at the causes of temperature exceedances in the Yampa and potential technologies that could help reduce high temperatures. The study could not pinpoint an exact cause of high temperatures, but a lack of riparian shading, nearby hot springs and Lake Catamount — an upstream, shallow reservoir — may be contributing factors.
“It’s probably a combination of these things, but if there’s one issue, we can’t point to it,” Carr said. “One of the reservoirs, Catamount, is small and shallow, so that acts as a bathtub that warms in the sun.”
The report presented five options for reducing temperatures at the city’s wastewater-treatment plant: passive cooling ponds/wetlands; cooling towers; pretreating warm water released from Old Town Hot Springs; water-quality trading using riparian shading; and a hybrid of water-quality trading with a cooling pond. City officials prefer the hybrid option because although riparian shading can help cool river temperatures in the summer, the temperature standards are also exceeded in November, when the leaves have fallen off the trees. A cooling pond could be a solution for that month.
City officials are also hoping that they could get credit for previous and current river restoration work as part of a future water-quality trading program. The city’s parks and recreation department, along with Diggin’ It Riverworks, began a restoration project on the Yampa behind the Flour Mill on Sept. 22. The project aims to improve river access, aquatic habitat, bank stabilization and recreational opportunities. Crews will also plant additional vegetation and trees to help cool river temperatures.
The city has submitted the alternatives analysis outlined in the engineering report and its preference to develop a water-quality trading program to CDPHE, which is currently reviewing the analysis. In Colorado, water-quality trading programs have traditionally been focused on pollutants. If Steamboat develops a program specifically to address temperature, it would be the first of its kind in the state.
“We know the city of Steamboat is not the only community having issues,” Carr said. “With climate change, there is no better time to start working toward a solution than now.”