The Downstream Effects of Wildfire

Protecting sensitive aquatic ecosystems in the heart of southwestern Utah’s population boom
By Lindsey Winkel
Intermountain Region
September 7, 2023
In the southwestern corner of Utah where the Colorado Plateau, the Great Basin, and the Mojave Desert converge, is the sprawling red rock city of St. George. According to the 2022 U.S. Census, St. George and the surrounding cities in Washington County is the fastest growing metropolitan area in America, having grown more than 30% in the last decade.

Southern Utah is famous for its monumental geography. Roughly six million years ago, ancient water drainages formed the Colorado River, carving out the canyon country of the Colorado Plateau and revealing layers of earth’s history like a slice out of a tall cake. Today, the remnant river system and its tributaries are the lifeblood for much of Western America, and Washington County residents rely on the Virgin and the Santa Clara rivers for their water.
Despite the region’s arid climate, the Virgin and the Santa Clara are home to a unique variety of plant and animal species that are found nowhere else in the world. As water use continues to evolve to suit the growing needs of human communities, many fish species, like woundfin and Virgin River chub, are continually on the precipice of extinction. Especially important to the Santa Clara River is spinedace, a minnow species that has been proposed twice to be federally listed as endangered. Since the 1990s, a conservation agreement has been able to keep spinedace off that listing, through dedicated monitoring by wildlife biologists and technicians with the Utah Department of Wildlife Resources, and the Virgin River Resource Management Recovery Program.
“The goal of the program is to conserve, enhance, protect, and recover native species in the Virgin River, while at the same time enhancing the ability to provide water for meeting human needs,” said Steve Meismer, the local coordinator for the program. “So, kind of two disparate goals in many respects, certainly out here in the West, trying to have enough water for the native species, while at the same time trying to provide water for one of the fastest growing counties in the United States.”
In nature, a domino effect
Just north of St. George is the Pine Valley Ranger District of the Dixie National Forest. The western slope of the Pine Valley Mountains is home to the headwaters of the Santa Clara River, which winds its way down through quiet farming communities until it confluences with the Virgin River in a modern suburb of St. George, hidden by willows and reeds, and muted by the whirring buzz of Interstate 15.

Recently, the United States Department of Agriculture’s Forest Service identified the Pine Valley Ranger District as one of 21 landscapes that are at risk for high-severity wildfire. Wildfires burn off the already-scarce vegetation of desert ecosystems. Without plants to hold the soil in place, a sudden storm that desert ecosystems rely on could quickly cause catastrophic flooding, sending a slide of debris down a slope and into waterways.
“The number one biggest threat to fish in southern Utah is wildfire,” explained Richard Hepworth, the Aquatics Program manager for Utah’s Division of Wildlife Resources. “A wildfire in the Pine Valley mountains has the potential to kill fish in the Virgin and Santa Clara rivers and downstream into Arizona and Nevada.”
Lake Mead, in Arizona, is the final destination of the Virgin River. From Pine Valley, that’s more than 100 river miles away.
Michael Golden, a previous fish biologist for the Utah Division of Wildlife Resources who now works on the Dixie National Forest, has seen the devastating effects for himself. In 2002, the Sequoia Fire on the southeast side of Pine Valley burned the headwaters of South Ash Creek and Leap Creek — tributaries of the Virgin River. At the time, both creeks contained conservation populations of Bonneville cutthroat trout.The flooding and consequent water quality issues wiped out the fish populations in those streams, and because of the habitat degradation that occurred they were still unable to support populations 15 to 16 years later, even after multiple attempts at reintroductions. Because of the lack of success, Leap Creek is no longer being managed for Bonneville cutthroat trout.

“In addition to the direct impact to water quality, debris flows can actually change the configuration of the stream. So you have the impact of that material coming down and killing fish, but also the aftermath of it where the habitat is not the same anymore, and might not be for decades, or even longer,” he explained.
Golden compared the loss of these species to a canary in a coal mine. He explains that a disturbance's impact on the environment can change our use of the land, like the amount of water that farmers can use for irrigation. If a species becomes listed as endangered, land use can become even more restricted, such as the ability to harvest timber, allow grazing, or even to recreate in the local reservoirs.
“The impacts that are happening to the fish in the stream ultimately are indicators of things happening to their surroundings that could impact people,” he said.
St. George primarily uses the Virgin River for drinking water, but after a flooding incident the Washington County Water Conservancy District started working on a 20-year plan to be able to use the Santa Clara as a backup source, according to Meismer.

The Dixie National Forest is working with several partners to reduce hazardous fuels in the Pine Valley landscape to prevent high-severity wildfire and maintain a healthy watershed. The Bureau of Land Management is treating adjacent public lands, and Utah Forestry, Fire & State Lands is working with private landowners, bringing the entire at-risk landscape to a total of 402,000 acres. Over the next ten years, excess fuels will be removed with the help of recent funding from the Bipartisan Infrastructure Law and the Inflation Reduction Act, and keeping water available for residents both above and below the surface of these vital waterways is just one of several intended goals for the project.
See more photos of the landscape and wildlife biologists at work for the Virgin River Recovery Program.
You can read more about what’s happening on the Dixie National Forest and its Wildfire Crisis Strategy on its webpage.