Effects of Oil and Natural Gas Development on Native Coldwater Fish Communities
Photo of Colorado River cutthroat trout

The Colorado River cutthroat trout currently inhabits just 13% of its historical range in Wyoming. The Wyoming Game and Fish Department lists it as a Species of Greatest Conservation Need and the U.S. Forest Service Rocky Mountain Region lists it as Sensitive. Although the mottled sculpin and mountain sucker are considered more secure, little is known about the ecology of non-game fish species in southwestern Wyoming.

Project Partners

University of Wyoming

Wyoming Game and Fish Department

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Contact Annika Walters


Why Be Concerned about Native Fish Communities?

The presence of native fish communities in southwestern Wyoming’s streams indicate good water quality. Keeping this fish, community intact supports the overall health of streams and entire watersheds. Important species that are part of this community include, the Colorado River cutthroat trout--a highly valued sport fish that brings revenue to local economies; the mottled sculpin which serves an important role as trout prey; and the mountain sucker, a species that helps to clear algae from streambeds. Effects of oil and natural gas development on fish habitats and communities are a significant concern in southwestern Wyoming, but little science has been conducted to identify and quantify potential effects. Suspected effects include: loss of vegetation cover; pollution from oil and gas spills; and high levels of sediments and salts that erode from denuded slopes or run off from roads and into nearby streams. An understanding of how energy development can affect aquatic habitat and fish will help land managers determine appropriate development levels and prioritize species or areas where monitoring and protection measures might be appropriate.

USGS ecologists and students with the Wyoming Cooperative Fish and Wildlife Studies Unit at the University of Wyoming have been studying native coldwater fish communities in the WLCI region. We compared native fish communities in streams experiencing a range of oil and gas development. Our goals were 1) to determine the effects of oil and gas development on water quality, habitat quality, and fish, 2) to evaluate potential mechanisms through which oil and gas development can affect fish, and 2) to assess physiological and immunological effects of oil and gas development for fish. These correspond to WLCI’s management needs to: 1) identify condition and distribution of key wildlife species/habitats, and species habitat requirements, and 2) evaluate wildlife and livestock responses to development.

Key Findings

  • Study sites with higher levels of oil and natural gas development had
    • less shrub cover,
    • fewer macroinvertebrate species,
  • and higher levels of
    • suspended sediments
    • dissolved salts, and
    • polycyclic aromatic hydrocarbons (pollution from oil and gas).
  • Cutthroat trout and mottled sculpin abundances were lower in sites with high levels of oil and natural gas development, whereas mountain sucker abundances were similar across study sites. This indicates that trout and sculpin may be more sensitive than suckers to effects of oil development.
  • The most important factors determining fish presence varied by species. The presence of cutthroat trout and mottled sculpin was associated primarily with fine-scale habitat features, such as willow cover and streambed composition. Mountain sucker presence was associated more with larger-scale habitat features, such as slope and water temperature.

Study Objectives

The ultimate goal of this research is to determine how oil and natural gas development affect native fish habitat and how altered habitat can influence the presence and abundance of native fish species.

  • Assess how different levels of oil/gas development affect fish habitat, water quality, and the presence of native fish.
  • Determine which fish species are most sensitive to effects of energy development and explore species-specific responses.
  • Collect precise streamflow measurements at multiple locations to coincide with fish study sites and evaluate how hydrology and development may interact to affect fish abundance.
  • Determine where groundwater inflow plays a significant role in sustaining streamflow.
Photo of Dry Piney Creek with oil or gas development nearby.

Dry Piney Creek winds through areas affected by oil and gas development in southwestern Wyoming.

How Will Our Studies Help Native Fish Conservation?

Small streams can be crucial for survival of native fish species. An understanding of streamflow, and in which stream sections flow is sustained throughout the year, will help us understand changes and differences in aquatic communities. We are evaluating groundwater interactions with small streams, such as the effects of groundwater return flow or recent precipitation on streamflow through collection of precise streamflow measurements on Fogarty Creek, Dry Piney Creek and South Beaver Creek. We will use streamflow data to help interpret aquatic species distribution and provide insights into the mechanisms of sustaining small streams in the upper parts of watersheds. Resource managers can use this knowledge of the processes that control streamflow to support resource management and planning decisions.

Some of the native fish that live in southwestern Wyoming’s coldwater streams are habitat specialists. The Colorado River cutthroat trout and mottled sculpin prefer cold, swiftly moving streams with rocky or gravelly streambeds. At the habitat scale, resource managers can use this new information to target sites for reducing sediment loads, restore stream vegetation cover, and prevent petroleum spills. At the landscape scale, the information gained through this work will help resource managers determine appropriate development levels for a given watershed so that habitat and stream function are maintained. The information also helps to point out priority areas in need of monitoring and protection measures. Finally, the absence of native coldwater fish in any one stream or drainage can alert resource managers that stream habitat and water quality may be in decline.

Photo of researchers taking measurements along stream
Photo of oil residue in Dry Piney Creek.
Photo of mountain sucker.

USGS researchers measure characteristics of coldwater fish habitat in southwestern Wyoming study sites, including streambed composition, willow cover and streamflow.

Oil residue left over from a pipeline spill that flowed into Dry Piney Creek. Oil spills can release hydrocarbon compounds into streams which can affect fish growth and development.

Mountain sucker populations are robust throughout the Dry Piney and South Beaver drainages in the Green River drainage.

Project Products: Maps, Papers, Data, and Other Tools