An Idaho State University research team has received a $1.3 million grant to study how streams that typically go dry for much of the year affect downstream water quality.
The four-year project, which involves eight universities sharing $6 million in National Science Foundation funding, should shed light on an issue that’s been hotly debated recently and has important ramifications for agricultural producers.
The researchers say their work could also help water users better understand their supply outlook. Thus far, there has been little research done on intermittent streams.
In 2015, the Obama Administration’s EPA approved revisions to the Waters of the U.S. Clean Water Rule, which requires permits for discharges, dredging or dirt fill of regulated waters. The 2015 Rule specified that any waterway with a bed, a bank and a high-water mark, including many streams that flow only intermittently during the year, would be subject to regulation. It also applied to ponds in or near the floodplain of a protected waterway and water bodies that weren’t connected to navigable waters but still had a “significant nexus” with them, such as vernal pools.
Opponents, including many agricultural producers, argued the rule represented a government overreach, potentially expanding regulation to “every puddle” on a farm or ranch.
A repeal of the rule by President Donald Trump took effect on Dec. 23, 2019, revising the definition of “Waters of the U.S.” to cover only streams that flow and are connected to navigable waters in a “typical year.”
Trump’s EPA said in a press release that the updated definition provided “greater regulatory certainty for farmers, landowners, home builders and developers nationwide.”
The ISU team’s co-lead investigators are Sarah Godsey, an associate professor of geosciences, and Rebecca Hale, an assistant professor of biological sciences specializing in water quality. The team also includes Professor Kathleen Lohse, who is an ecosystem scientist; Ken Aho, an associate professor of community ecology and statistics; and Yaqi You, a visiting assistant professor who recently left for New York but will remain involved in the project.
Godsey and Hale conducted a pilot project last summer evaluating the impact of intermittent tributaries on the water quality in Gibson Jack Creek in Pocatello.
“Our pilot data suggests that intermittent headwater streams, even though they’re tiny and not flowing all the time, may have an outside impact on downstream, perennial water quality,” said Godsey, who is tasked with studying spacial patterns of stream drying. “That’s surprising.”
Godsey explained intermittent streams may support different populations of microbes that break down leaves and other material in streams. Furthermore, intermittent streams may cause leaves, debris, manure and other materials that build up over time to flush all at once, temporarily elevating nutrient concentrations downstream.
There’s a national database of intermittent streams, but Godsey said about half of them are incorrectly classified. For example, she explained the database includes no intermittent streams that flow into Gibson Jack Creek, though she and Hale found several of them when they conducted their pilot study.
“I definitely hope we’re going to help improve the models that say when and where the streams are drying,” Godsey said.
Their data will be pooled with research by investigators from University of Kansas, Haskell Indian Nations University, Kansas State University, University of Alabama, University of Mississippi, University of Oklahoma, Alabama A&M and University of Southern Mississippi. The researchers will focus on three streams in three different regions — the western mountains, the central plains and the southeastern forests.
The mountain streams include Gibson Jack, a stream in southwest Idaho and a stream near Boise.
Students with the Shoshone-Bannock Youth Program in Fort Hall will be invited to help with water sampling and to learn about the water-quality research.
Godsey and Hale were among about 30 scientists from throughout the world who attended a workshop in New Mexico a little more than a year ago, where the participants sought to write a collective paper on the different aspects of water quality in intermittent streams.
“We realized that most of the data we needed wasn’t available. ... There was a clear gap in the science,” Godsey said.
A subset of the participants at the workshop collaborated on getting the cooperative grant to fill in some of the missing data. Godsey said project participants are still purchasing equipment; the ISU team will hire students and postdoctoral researchers to aid in collecting the data this spring and summer.
Hale emphasized that the grant has far-reaching implications in many different areas and is not specifically focused on agriculture.
“Ultimately, I think it would be great to look at how these (intermittent streams) interact with different land uses,” Hale said. “These might not flow all the time, but they are connected with navigable waters and they influence water quality downstream.”
For example, Hale said fertilizer applied on a farm field near an intermittent stream eventually makes its way into a downstream, perennial waterway.
Godsey added, “We hope that this basic science helps us to understand how these small, intermittent headwaters can have impacts on the downstream waterways that we depend on.”