Study: Low Flows Compound Development's Impact On Fish

Nov 22, 2019

Scientists at the University of Wyoming wanted to know how fish fare in streams near energy development. Their results were recently published in the Journal of Applied Ecology and paint a picture of how human disturbance and less water can crunch the habitat that some fish need to survive and thrive.

Low stream flows exacerbate the stress some fish face living in the shadows of oil and natural gas development.

That's what University of Wyoming researchers found from studying the mottled sculpin and mountain sucker in the Dry Piney and South Beaver stream drainages. Both tributaries of the Green River are inside ExxonMobil's LaBarge natural gas field in southwestern Wyoming.

"We essentially found that in areas where development is high, low discharge is likely to have an especially negative effect on species ability to persist over time," said lead author Rich Walker.

Walker is now an adjunct professor at American University in Washington, D.C. He signs off his emails with the phrase "best fishes" instead of "best wishes."

The scientists tramped through scrubby sagebrush and battled water-loving willow trees to get to their 64 study sites over the course of seven years. They waded through streams, one holding a beeping electroshocker, used to stun fish, and two others trailing with nets.

"We collected fish using backpack electrofishing," Walker said. "So if you can imagine someone standing in a stream with waders on and walking around with a backpack electroshocker you look like a, it's a Ghostbuster style backpack shocker."

The energy industry in the Upper Green River Basin is often studied in terms of the impact on more charismatic critters like pronghorn, mule deer and sage grouse. But another scientist on the team, Annika Walters, says aquatic species are also affected.

"Oil and natural gas development will require the construction of roads and well-pads and pipelines," Walters said. "And so this increased rate of surface disturbance can increase sediment input into our streams."

Walters is a research ecologist for the United States Geological Survey's fish and wildlife cooperative unit. While the sculpin and sucker fish might not draw anglers like cutthroat and brook trout do, Walters says they matter too.

"I think the short answer is that, you know, an intact native fish community is indicative of good water quality and a healthy watershed and that's something that's really important for all of us," she said.

The sucker wasn't harmed as much by energy development as the sculpin - suggesting fish vary in their sensitivity. Its numbers slightly grew in areas where there was land use change.

The scientists were interested in looking at how natural fluctuations in water flow also complicated the picture. Fish are happier during higher flow years. But climate projections show the mountain west will have warmer winters with less snow, more rain, earlier melt offs and lower stream flows.

"So that can have an effect on the availability of habitat and the quality of that habitat late in the summer when fish really need it most," Walker said.

This research is part of the broader Wyoming Landscape Conservation Initiative. That's a decade-long effort to assess and enhance land and water habitats in southwestern Wyoming and facilitate responsible development.

"Knowing when local populations will be hit the hardest is an important conservation tool," Walker said.

Amanda Withroder works for Wyoming Game and Fish's habitat protection program. She supervises teams of biologists who review energy development projects, look for conflicts and if necessary, make recommendations to minimize disturbance.

"The location of the project and the size of it are the two main things that we're looking at," she said.

Changes can be made to help fish specifically, like keeping development as small as possible and away from waterways.

"So for instance if the operator is proposing a 10-acre well pad, and we can work with them and get it down to like a 5-acre well pad or an 8-acre well pad, the less acres disturbed, the less erosion, the less dirt, is going to be moving around on that landscape," Withroder said.

Restoration plans are in the works for some of the area researchers studied. Pinedale's Bureau of Land Management office is working with the Sublette County Conservation District on a project encompassing the Dry Piney Creek, where the scientists worked, Dry Basin Draw and Birch Creek watersheds. While site specifics still need to be nailed down, assistant minerals and lands field manager Doug Linn said efforts will focus on restoring stream banks and channels to a more natural state.

"What this project is looking at is everything from anthropogenic, or human caused erosion, to natural erosion," Linn said. "How can we reduce the amount of sediment that is moved off of the land's surface into the Upper Green River itself."

Fences that block silt from getting into the river and replanting willows are just a few ways fish habitat near industry development can be improved. Twenty projects are identified as a priority and will likely get underway in the next year or two.