Last updated: August 29, 2025
Article
After Fire, Process-Based Restoration Creates Habitat for Native Fish
The Strawberry Fire devastated Bonneville cutthroat trout populations in a Great Basin stream. By mimicking nature, scientists are helping this ancient fish make a comeback. They’re also hoping to encourage beavers—those skilled ecosystem engineers—to return.
By Scott Shahverdian and Meg Horner
About this article
This article was originally published in the "Features" section of Park Science magazine, Volume 39, Number 2, Summer 2025 (August 29, 2025).
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In 2016, a lightning strike ignited the Strawberry Fire, which burned 2,790 acres in Great Basin National Park.
Among the affected areas were riparian zones along Strawberry Creek. The creek is one of several perennial streams that start in the park at high elevation and ultimately supply water for agriculture in Utah and in Nevada, the driest state in the U.S. These streams are also critical habitat for native plants and wildlife, like the Bonneville cutthroat trout, Utah’s state fish.
The fire severely degraded habitat conditions for the trout in Strawberry Creek. It burned riparian vegetation and increased water temperature. It caused the channel to erode and led to increased sedimentation. “Strawberry Creek was the park’s most productive BCT [Bonneville cutthroat trout] stream before the Strawberry Fire,” said Jonathan Reynolds, fish biologist at Great Basin National Park. “But immediately after the fire, we didn’t observe any fish in the severely burned portions of the stream.”
National Park Service and other scientists used low-tech, process-based restoration (LTPBR) to restore the creek. This approach works with natural processes like erosion, deposition, and local flooding to improve stream conditions. Between 2021 and 2024, we built and maintained 74 LTPBR structures in Strawberry Creek. Initial restoration outcomes have been promising. Internal data show substantial deposition at the structures. This is an important step in restoring previously deepened channels. The structures created more complex instream habitat and increased the number of deep pools, rare in this watershed. They also raised water tables locally, benefiting adjacent riparian areas. So far, the number of Bonneville cutthroat trout has doubled.
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Critical Habitat for an Ancient Species
Mountain streams like Strawberry Creek provide most of the remaining habitat for Bonneville cutthroat trout. Today, these native trout are found in northern Utah and parts of Nevada, Idaho, and Wyoming. This species is a holdover from ancient Lake Bonneville, which once stretched from northern Utah and southern Idaho to eastern Nevada. The lake was connected to mountain streams, including ones that originated in what is now Great Basin National Park. Like their ancestors in Lake Bonneville, the trout require cold water temperatures to survive.
This species is a holdover from ancient Lake Bonneville, which once stretched from northern Utah and southern Idaho to eastern Nevada.
But like many mountain streams, as they flow into valleys below, their water temperatures rise, and stream flows are altered by agriculture or other demands. These conditions make lower stream sections uninhabitable for Bonneville cutthroat trout. As a result, higher, relatively pristine mountain streams like Strawberry Creek—and its riparian habitat—are critical to the trout’s survival.
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Dramatic Changes
Fire is a natural and necessary process in many ecosystems. Certain important tree species, for example, depend on fire for their reproduction. Lush and intact riparian vegetation growing along streams and rivers can be resistant to burning. Wetter soils and riparian plants are also inherently more resilient. This limits the negative effects fire has on streams and aquatic species. But despite the resilience of riparian vegetation, fire poses a substantial risk to isolated populations of native fish because of their restricted range. If a fire is large enough or the population small enough, an entire fish population could be lost.
If a fire is large enough or the population small enough, an entire fish population could be lost.
During and immediately after a severe fire, streams often experience dramatic changes. High temperatures, loss of streamside vegetation, increased sediment loads, and intense floods can change the structure of streams. Resulting channel incision, excessive deposition, and loss of woody debris simplify instream habitat. These changes negatively affect instream species like the Bonneville cutthroat. If the fish can’t move to new areas to find better habitat, these changes are particularly devastating.
“The majority of BCT that lived in the mid and lower parts of the stream were likely killed due to increased water temperatures,” Reynolds said. “During population surveys that first year, BCT were present at two out of nine survey sites, and the average population density was only 114 fish per mile. For comparison, a few years before the fire, the average population density was 755 fish per mile.”
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When the Strawberry Fire burned over Strawberry Creek, it consumed riparian vegetation, which provided shade and cover for trout. Channel incision led to towering stream banks and riparian plants no longer able to reach the water table with their roots. These conditions make it almost impossible for a stream to spread out during flood events. Floodwaters and continuous, fast-moving streams are hard places for fish to survive. In contrast, streams that can connect to their floodplains can withstand high flows by spreading water, sediment, and energy onto floodplains or into side channels. Slowing and spreading water create areas for riparian plants to grow and for fish to rest and hide.
Mimicking Nature
In Strawberry Creek, the restoration team used a specific LTPBR technique that relies on hand-built instream structures. These structures, called “beaver dam analogs” and “post-assisted log structures,” mimic naturally occurring beaver dams and wood jams. Both are critical to healthy fish populations and riparian habitat. The analogs are built with native woody vegetation and sediment, just like their natural counterparts. They help promote stream and floodplain health, especially after a wildfire.
Healthy streams and riparian areas are dynamic, and LTPBR enables and works with expected changes from floods or drought.
Because they are built by hand and use native materials, they are often less costly. They’re less likely to damage sensitive riparian areas than restoration that relies on engineering and heavy equipment. They are also supposed to change through time, mimicking what streams do naturally. Healthy streams and riparian areas are dynamic, and LTPBR enables and works with expected changes from floods or drought.
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Through this work, we aimed to improve stream conditions for Bonneville cutthroat trout. The structures trapped sediment and raised the stream channel. This increased the likelihood that peak flows would connect the stream to its floodplain. Like beaver dams, the analogs created deep pools, critical habitat for fish to rest and survive the winter. Adding wood to the stream with log structures and beaver dam analogs also created more complex instream habitat, benefiting aquatic species.
Expert Help
"Land managers and restoration practitioners need multiple tools to restore riparian resources,” said former Great Basin Resource Program Manager Ben Roberts. Roberts helped kickstart the project. “[These resources] provide critical benefits for visitors, downstream users, and wildlife,” he added. “Luckily, we have subject matter experts within the NPS that can assist parks with finding the right organizations and tools to meet our objectives and mission."
“Land managers and restoration practitioners need multiple tools to restore riparian resources.”
In 2021, Great Basin National Park worked with the National Park Service’s Water Resources Division and Utah State University to plan and implement this project. We invited other groups to help out, as well as staff from other parks. The Nevada Department of Wildlife, Nevada Conservation Corps, and Bureau of Land Management all participated. Utah State University staff provided training during the first phase of implementation. National Park Service staff led and completed the subsequent restoration in 2022–2024. By working with outside experts and other federal and local partners, we boosted the park’s capacity to implement LTPBR.
Positive Signs
The restoration team conducted Bonneville cutthroat trout population surveys annually at nine sites along Strawberry Creek from 2021 to 2024. We used a backpack electrofisher and nets for the surveys. During those three years, the number of captured Bonneville cutthroat more than doubled to 136 (estimated density of 511 fish per mile). We found Bonneville cutthroat at eight of the nine survey sites. Such a distribution had not been recorded since before the 2016 Strawberry Fire.
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“We regularly surveyed for BCT in Strawberry Creek to see how they were responding to post-fire conditions and our restoration actions,” said fish biologist Reynolds. “Surveys also helped us avoid interfering with any important life stages, like spawning, when building [analogs]. Our surveys suggest that the BCT population in Strawberry Creek is returning to pre-fire levels.”
National Park Service staff established streamflow monitoring stations upstream and downstream of the project area. From 2020 to 2024, we took regular measurements from May to October at each monitoring station. We took additional measurements as resources allowed. Our data show that the positive ecological changes in the creek have not impaired water delivery to downstream users, who rely on flows from Strawberry Creek to support agriculture.
In 2024, park staff discovered a few aspens felled by an apparently far-ranging beaver, the first sign of the species in Strawberry Creek in 19 years.
The restoration team also monitored changes in flow type by recording the proportion of the stream that was fast and free-flowing riffle or run habitat versus sections with slower backwater pool habitat. We recorded flow type once a year by walking survey transects and measuring the length of pools and backwaters. Between 2022 and 2024, slower-moving pool habitats increased by 10 percent.
In 2024, park staff discovered a few aspens felled by an apparently far-ranging beaver, the first sign of the species in Strawberry Creek in 19 years. The nearest known active beaver dams were more than five miles downstream. The aspen chewed down by the beaver fell right on top of one of our recently built beaver dam analogs. This was an exciting and welcome discovery.
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Beavers are effective ecological engineers. Through their dam building, they can improve stream habitat, increasing its complexity. This benefits a wide range of species, including trout. The deep water that backs up behind a beaver dam provides great habitat for fish and a safe place for beavers. It also slows water down and releases it downstream more gradually. These are all important outcomes that land managers hope to achieve.
Only the Beginning
Other approaches to stream restoration tend to be “one and done” projects. But LTPBR is founded on the principle of ongoing stewardship and engagement. Initial phases often create new opportunities for subsequent phases. “Building instream structures is the beginning of restoration,” said Derek Schook, a hydrologist with the Water Resources Division. “The restoration will take place through time, as streamflow and sediment interact with the [structures].”
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Degraded riparian areas and severely down-cut channels take time to recover. But monitoring indicates that our restoration treatment is already having positive outcomes. Historically, in Strawberry Creek, the deepest pools were likely associated with natural beaver dams. Remnants of these dams can still be found in the upper sections of the creek. Until we started this project, the creek had few such pools. By building beaver dam analogs, we created more deep-pool habitat. In years with lower streamflow, these pools persisted. They provided resting and winter habitat for Bonneville cutthroat trout.
During high-flow years, many of the pools filled with sediment. This led to a wider channel, capable of spreading peak streamflow. One large analog built in 2021 initially created a pool about three feet deep. In the following years, this pool filled with sediment, capturing nearly 500 cubic feet of it. The erosive potential of flooding was thus reduced, creating areas for riparian vegetation to take hold.
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By building wood jams, we also widened the stream channel and captured sediment. This was an important step in restoring severely down-cut channels. Wood jams help restore down-cut channels and provide refuge for trout during high flows. “Restoring instream habitat heterogeneity after the fire was a critical goal for enhancing stream function,” said Schook. “The instream structures the crews built affect flow hydraulics and thus add microhabitats that help various stream and riparian species.”
A Natural Fit
Low-tech, process-based restoration is a natural fit for the National Park Service, which champions long-term stewardship and adaptive management. Ongoing monitoring and management of Strawberry Creek will continue to improve the creek’s post-fire condition. The project can also give National Park Service staff the tools and knowledge to effectively manage streams in this and other parks. With continued work and a little luck, we hope to create better habitat for beavers to move back into Strawberry Creek. They’ll continue the work we’ve begun to ensure the creek’s long-term health.
About the authors
Geomorphologist Scott Shahverdian works at Utah State University and a private consulting company in Logan, Utah.
Meg Horner is a biologist at Great Basin National Park. Photo courtesy of Meg Horner.
Cite this article
Shahverdian, Scott, and Meg Horner. 2025. “After Fire, Process-Based Restoration Creates Habitat for Native Fish.” Park Science 39 (2). August 29, 2025. https://www.nps.gov/articles/000/psv39n2_after-fire-process-based-restoration-creates-habitat-for-native-fish.htm