From The Steamboat Pilot & Today (Shelby Reardon):
As a Yampa River Botanic Park team member, [Jeff] Morehead removes the diversion dam on Fish Creek under U.S. Highway 40 every year. The water flows through two arches under the road, and the dam keeps the water level high enough in one of them so water diverts to the Yampa River Botanic Park.
Each fall after Halloween, the park closes and Morehead removes the dam. This year, as requested by Steamboat Springs Water Resources Manager Kelly Romero-Heaney and Public Works City Engineer Ben Beall, Morehead removed the structure a bit earlier. Additionally, he created a wing dam of rock and fabric to divert the water through one arch instead of two, deepening the flow of water.
“I was just happy to help,” said Morehead. “You could tell the fish were going right past me while I was doing it. I was like, ‘Holy crap, this is absolutely working.’”
Without the diversion, waterflow through both arches isn’t deep enough to allow the fish to swim and jump through the box culvert steps. The middle arch has one large step of about 18 inches, according to Morehead, which would be nearly impossible for the fish to leap over.
“It’s staircased in a way that the drops are like 18 inches and there’s a long flat that approaches the staircase, so the whitefish can’t really swim and get a jump over that 18 inches.”
There used to be a third arch, but as of summer 2019, a sidewalk underpass filled the far right arch. That left the far left arch as the only viable option for fish to get upstream.
With more water flowing through the arch, it allowed whitefish to swim upstream and spawn in the waters of Fish Creek. Development and low water levels have made it harder to access their main spawning tributary for the fish living in the headwaters of the Yampa. The whitefish spawn, or lay their eggs, in early to mid-October. The eggs will hatch in the spring before the waters reach their peak flow.
As seen in a video taken and edited by Morehead, the whitefish seem to have utilized the access point to Fish Creek.
Whitefish populations in the Yampa River Basin have been dwindling for years, so, as part of the Yampa River Health Assessment and Streamflow Management Plan adopted in 2018, the city of Steamboat Springs vowed to “promote native fish populations from further decline and promote range expansion where possible.” The Fish Creek diversion is just one way the city is working to accomplish that task.
The mountain whitefish isn’t endangered, but its numbers are falling in the Yampa River Basin, where it’s one of two native salmonids in the area, the other being cutthroat trout. The species is also found in Colorado in the White River Basin. They live in the Northwest in cool waters of high elevation streams, rivers and lakes, particularly in Montana, Idaho, Oregon and Washington.
While they are thriving in other areas of the country, including the White River Basin, they are struggling in the Yampa River Basin as noted in samples taken from the river every few years, most recently conducted by Billy Atkinson, an aquatic biologist for Colorado Parks and Wildlife.
A huge reason for their decline is the non-native northern pike. Pike are predacious fish and feed on the whitefish. There have been efforts to control the pike population in the area, which is another goal of the Yampa River Health Assessment and Streamflow Management Plan.
Mountain whitefish are doing well in the White River, where there are no northern pike to prey on the native fish. There are other ecological factors that can be attributed to the whitefish’s success in the White River basin, but no pike is the biggest difference between that system and that of the Yampa River.
Predation is just one issue plaguing the whitefish.
The whitefish, which can grow up to 2 feet, loves cold water in high elevations. A 20-year drought in Colorado has brought on some particularly rough water years, though, lowering the flow in rivers across the state.
The Yampa River was extremely low this year, closing to usage Sept. 2 when the streamflow dropped below 85 cubic feet per second. Shallower water is warmed by the sun far easier than deeper water, causing stress to fish that prefer cooler temperatures.
Thankfully, there are already efforts in place to improve this on two fronts. The Upper Yampa Water Conservancy District releases water from Stagecoach Reservoir to improve river flow and prevent the loss of fish habitat when the water line lowers.
Additionally, the Yampa Valley Sustainability Council and Retree have been planting young trees on the banks of the Yampa in designated spots. When they grow, the trees will provide shade to the river, helping maintain lower temperatures.
This year, with water levels so low, the end of summer river closure extended into the fall to put less stress on the entire Yampa River ecological system. With low flow, fish, such as the mountain whitefish, concentrate in small pools due to limited resources.