Researchers Explore Coexistence of Roads and Watersheds

Study finds watershed-scale factors outweigh local road crossing effects on sediment runoff in Arkansas

Apr. 4, 2026 at 1:08am

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A highly textured, geometric abstract painting in earthy tones, depicting the interconnected natural forces and land use patterns that impact water quality in a rural watershed, without any text or identifiable elements.An abstract visualization of the watershed-scale factors that influence sediment runoff from unpaved roads in rural landscapes.Fayetteville Today

Researchers at the University of Arkansas System Division of Agriculture studied the impacts of unpaved roads on water quality in the Brush Creek watershed, a key drinking water source for northwest Arkansas. While they hypothesized that road crossings would be the main driver of sediment runoff, the data showed that broader watershed-scale factors like the extent of unpaved roads and pastureland had a greater influence. The findings will help guide more strategic conservation practices to reduce sediment and nutrient pollution in local waterways.

Why it matters

Northwest Arkansas is experiencing rapid growth, with a network of unpaved rural roads crisscrossing the region's watersheds and feeding into key drinking water sources like Beaver Lake. Understanding the complex relationship between roads, land use, and water quality is crucial for developing effective strategies to protect water resources in fast-growing areas with a mix of urban and agricultural landscapes.

The details

The researchers measured up to 13 tons of sediment entering Brush Creek during a single large storm event, highlighting the significant sediment loads already impacting the watershed. While they hypothesized that road crossings would be the main driver of sediment runoff, the data showed that broader watershed-scale factors like the extent of unpaved roads and pastureland had a greater influence. The findings will help guide more strategic placement of conservation practices, such as pairing on-farm biochar applications with road and pasture management to maximize water quality improvements.

  • The study was published in the Journal of Environmental Quality in 2026.

The players

Shannon Speir

An assistant professor of crop, soil and environmental sciences at the University of Arkansas and the Arkansas Agricultural Experiment Station, who led the research team.

Kathleen Cutting

The lead author and a program associate on the research team.

Brush Creek

A waterway that feeds into Beaver Lake, the primary drinking water source for northwest Arkansas.

Beaver Watershed Alliance

A group that has estimated that implementing road best management practices could reduce sediment loads to Beaver Lake by over 800 tons per year.

Arkansas Unpaved Roads Program

A program that the researchers plan to work with to share their findings and support targeted investments in road management.

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What they’re saying

“We were already out there regularly doing sampling — wading through the creek, collecting water samples up and down the watershed — and we kept driving over these unpaved roads to get to our sites. It was hard to ignore — ruts, loose gravel washing toward the stream, ditches routing runoff directly toward the water.”

— Shannon Speir, Assistant Professor

“The data just didn't support that cleanly. What did matter — a lot — was what was happening at the watershed scale: how much unpaved road network existed in a sub-watershed, how much pastureland was present and what the flow conditions were.”

— Shannon Speir, Assistant Professor

What’s next

The study's findings will help guide future research and conservation efforts, including a $1.9 million EPA-funded project to study how adding biochar to poultry litter can improve water quality in the Brush Creek watershed.

The takeaway

This research highlights the complex, interconnected nature of roads, land use, and water quality in rapidly growing regions like northwest Arkansas. By taking a holistic, watershed-scale approach, the researchers were able to identify the most impactful factors driving sediment runoff, which will inform more strategic and effective conservation practices to protect local water resources.