Study sheds light on Great Salt Lake’s impounded wetlands, an oasis in the desert

A monitoring well in a Great Salt Lake wetland (Credit: Rebekah Downard)

Fieldwork in the wetlands around the Great Salt Lake can be a mixed bag for researchers. On one hand, there’s the persistent smell of hydrogen sulfide characteristic of these ecosystems.

“It kinda gets in your pores,” said Karin Kettenring, assistant professor of wetland ecology at Utah State University. “After a day of working in the wetlands you go home and wash your hands a few times, you take a shower, and the next morning you sniff your hands and they still smell like rotten eggs.”

And that’s on top of the “lake stink” that wafts up from the bottom sediments exposed by the Great Salt Lake’s fluctuating water levels.

But then there are the millions of waterfowl and shorebirds — species like the American avocet and black-necked stilt — that rely on this oasis in the desert as a critical stopover site in the midst of their North American migratory routes.

“If you’re out doing field work in the spring or the fall during the migration periods you’ll be surrounded by hundreds of thousands of birds, which is a pretty phenomenal experience,” Kettenring said. “They’re beautiful birds. They have beautiful calls. They’re very elegant.”

Many wetlands around the lake are managed to bolster habitat for migratory birds, especially the ducks that draw thousands of hunters to Great Salt Lake marshes each year. These wetlands are impounded and their water levels manipulated, but scientists have no clear picture of how the management practices actually affect wetland health across the lake.

“We know a lot about the discharge of the rivers that go into the Great Salt Lake, and a fair amount about the elevation of the Great Salt Lake, but what’s happening in between is generally unknown,” said Rebekah Downard, doctoral student in ecology at Utah State University’s Department of Watershed Sciences.

A diked Great Salt Lake wetland (Credit: Rebekah Downard)

Downard is leading a study of water levels and other dimensions of wetland health in dozens of sites around the lake. The study seeks to understand how impounded wetlands are managed while developing a better idea of what a healthy wetland looks like amongst the region’s arid climate and hypersaline waters.

Water levels in around half of the wetlands around Great Salt Lake are managed to cope with the seasonal loss of source water when the rivers are drawn down for agricultural uses. The managed wetlands are diked and the impoundments flooded when enough water is available before it’s diverted for the irrigation season.

“It’s the wetland plant growing season too, but a lot of that water is going to agriculture instead,” Downard said.

A monitoring well stands out in a Great Salt Lake Wetland (Credit: Rebekah Downard)

The idea is that these shallow reservoirs will preserve water in the wetlands throughout the growing season while creating habitat for ducks in the private hunting clubs and migratory bird preserves that surround the lake. But the patterns of water level management across the region isn’t well known, nor is it clear that storing water in the wetlands is the best plan for the ecosystem’s health and function.

To shed some light on both those areas of uncertainty, Downard installed monitoring wells equipped with pressure transducers at 25 impounded and 25 unimpounded wetland sites across the lake. From May to September, the instruments measure water levels every hour down to a meter below the soil and up to 60 centimeters above the surface.

In the meantime, Downard is sampling plant cover, plant species diversity and soil quality across the sites. After a few years, she’ll answer questions like how often and deeply impounded wetlands are flooded, how often they go dry, how that affects plant diversity and soil quality, and how that all compares to conditions in the lake’s more natural wetlands.

A Great Salt Lake wetland (Credit: Rebekah Downard)

As far as working conditions go, Downard is enthusiastic about her time in the wetlands. The Great Salt Lake’s wetlands tend to be less buggy and snake-infested than marshes in other parts of the country, even if they are prone to the occasional bout of lake stink.

“I’m from Utah,” she said. “That’s what home smells like to me.”

Top image: A monitoring well in a Great Salt Lake wetland (Credit: Rebekah Downard)