This blog was originally posted on the Great Salt Lake Watershed Enhancement Trust website on August 6, 2024. The Trust is co-managed by National Audubon Society and The Nature Conservancy.
As high temperatures continue to plague the West, wetland managers and state biologists across Great Salt Lake are already witnessing the deadly effects of warming waters as this year’s breakout of avian botulism begins to decimate birds.
“I was out on Farmington Bay last Saturday and saw a handful of dead birds already,” said Rich Hansen, waterfowl biologist and manager of more than 55,000 acres of wetlands including Ogden Bay, Harold Crane, Howard Slough, and Willard Spur Waterfowl Management Areas for the Utah Division of Wildlife Resources.
Avian botulism is a disease that causes paralysis in birds after they ingest a toxin produced by a bacterial spore. Botulism spores can survive for years within an ecosystem, lying dormant until proper anaerobic (oxygen-deprived) conditions exist, usually caused by warming, stagnant water. Without new water flows that essentially breathe oxygen back into the water, the spores come out of dormancy and are ingested by invertebrates. At Great Salt Lake, those invertebrates are mainly brine flies, brine shrimp, and midges, and in the more freshwater bays Corixids and Chironomids—the key food sources and fuel for hundreds of thousands of molting waterfowl and shorebirds during their fall migration through the Pacific Flyway.
Once birds ingest the infected toxins, paralysis will begin in their feet, leading birds to move to the water where they can swim by flapping their wings. Soon after though, the paralysis moves to their necks, causing many to die from drowning or starvation, rather than botulism itself. And once a handful of birds are infected, a feedback loop begins that’s nearly impossible to stop.
“Once one bird ingests those infected toxins and dies, the cycle starts over—maggots cover their bodies and other birds then ingest the maggots, leaving them infected as well,” said Hansen.
The disease is devastating and nearly impossible to eliminate, especially with Great Salt Lake’s ideal conditions for botulism outbreaks—warming waters, the presence of bacterial substrates such as decaying plant and animal matter, which both lead to a decrease in the solubility of oxygen in the water.
“Over my 23 years working on Great Salt Lake, I’ve seen it every year; it’s just a matter of degree,” Rich said, going on to explain that biologists can usually predict severe outbreaks as they often occur when dry years are followed by years with good runoff.
Last year serves as a classic case of these conditions: peak megadrought in 2022 was followed by record-breaking snowpack in 2023. As a result, 2023 saw an estimated 30,000 duck deaths from botulism, mostly on the west side of Willard Spur and in Bear River Bay. And yet, even when ideal weather patterns and conditions occur, severe botulism outbreaks are still fewer and further between thanks to the foresight of Utahns nearly 100 years ago.
From 1910 to 1930, Great Salt Lake lost more than 7 million ducks to one botulism outbreak after another. At the time, there were no managed wetlands, only the Bear, Weber, and Jordan River Deltas.
“That’s when biologists learned that we needed to put dikes and water control structures like impoundments in these systems, giving managers the ability to keep the water moving and avoid anoxic (lack of oxygen) conditions,” said Rich.
Following this realization, many major waterfowl management areas (WMAs) were built along the eastern and southern shores of Great Salt Lake, including Ogden Bay and Farmington Bay, as well as the Bear River Migratory Bird Refuge, and Duck Clubs like New State Duck Club, Bear River Club, and many more. Made up of a series of dikes and water control structures that keep water constantly flowing throughout the summer to prevent botulism from starting, these waterfowl management areas and the refuge have minimal outbreaks compared to unmanaged areas.
Managed, or impounded, wetlands and water control structures aren’t the only mitigation tactic in biologist’s arsenal though. Increased water flows, combined with the ability to control where the water moves, helps wetland managers to better control the spread of botulism, decreasing the number of annual bird deaths.
“Late summer water releases out of Willard Bay Reservoir save thousands to tens of thousands of birds from getting botulism,” Rich explained. “The fresh flows brought in by water releases increase oxygen levels in Willard Spur, eliminating the anaerobic conditions botulism requires.”
With wetland managers already seeing botulism cases this year, water releases such as this are more important than ever, especially as botulism peaks in September.
Mitigating botulism isn’t the only benefit of increased water flow and management. As the Great Salt Lake Watershed Enhancement Trust—its managers, National Audubon Society and The Nature Conservancy—the state, and other entities and partners work across specialties to get more water and better control structures installed, especially in WMAs and other wetland areas, collectively we can expect to see benefits including, but not limited to:
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Improved capacity to control phragmites
While it’s not certain how the invasive European plant found its way to Great Salt Lake, in the last decade phragmites have spread quickly across Great Salt Lake’s native marsh lands. The thick, dense weed requires a large amount of water to survive, consuming the already scarce resource, and choking out crucial wetland habitat for birds and other species.
Wetland managers have employed many tactics to control the growth and spread of phragmites on Great Salt Lake including herbicide application, controlled burns, mowing, and most recently grazing by cattle to reduce seed production, but water control remains one of the most effective tools.While it might sound counterintuitive, directing water flows into stands of phragmites allows it to grow healthy, improving the effectiveness of herbicide sprays. Another tactic of water control is flooding sites with fresh water flows to help decompose phragmites litter or moving water away from phragmites to drought stress the weeds and promote growth of native, drought-tolerant plants.
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Increased precipitation levels
It’s well known that Great Salt Lake contributes to what’s been deemed “the greatest snow on earth.” Evaporation from Great Salt Lake increases the moisture content of storms moving across the state, providing “lake effect” snow that contributes to 5-8% of Utah’s base snowpack. Recently a research team found that a 25% decrease in Great Salt Lake’s area, results in roughly a 10% decrease in total precipitation.
Increasing water flows into Great Salt Lake will help to increase the size of the lake, bringing it back to a healthy lake level, and consequently increasing the likelihood of greater precipitation events and lake effect snow. As snowpack provides 95% of Utah’s water, this investment in the lake would also prove a wise and thoughtful investment in the future of the state and its residents.
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Improved air quality and environmental equity
In 2022, when Great Salt Lake shrunk to its lowest water levels on record, one of the main concerns facing Utahns was the concentration of toxic heavy metals in the dust of the dry lakebed. During weather events, dust storms can carry these metals and pollutants, depositing them not only in surrounding communities but onto the snowpack causing earlier snowmelts and polluted water sources. As more lakebed is exposed, the impacts of a drying lake—financial, health, and environmental—will continue to mount in cost and severity.
Increasing water flows to restore the lake to healthy water levels not only reduces the impact of dust events, providing cleaner air quality and a slower, more natural rate of snowpack melt, but a recent study released by One Earth Journal suggests it could reduce disparities and environmental inequities experienced by communities disproportionately affected by harmful dust exposure.
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Increased habitat for shorebirds and other species
Each year, more than 10 million birds, including more than 330 species, utilize Great Salt Lake and its surrounding wetlands, dependent on the complex food web of the lake. As water systems throughout the West experience rapid change, Great Salt Lake has remained one of the most significant wetland habitats in the Pacific Flyway for migrating birds. As lake levels decline though, habitat loss can impact millions of birds, having hemispheric consequences.
Increasing water flows gives wetland managers the tools to sustain and improve wetland habitats and continue to provide essential habitat for the hundreds of species that depend on them for survival. More habitat and water enables the disbursement of birds, leaving them less concentrated and reducing the spread of botulism and other avian diseases.
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Improved management of salinity content in the South Arm of the Lake
Under normal conditions, the salinity levels in the lake’s South Arm, such as Gilbert Bay, are optimal for a robust brine fly, brine shrimp (and cyst) population. Declining lake levels increase the level of salinity, interrupting the balanced network and leaving algal mats on exposed microbialites to become desiccated, impacting the viability and reproductive ability of the brine fly and shrimp populations and putting the entire South Arm at risk of ecological collapse.
With increased water flows, and better ability to control where the water moves, managers can ensure that the South Arm salinity remains at a viable level for ecological balance, ensuring the production of brine flies, brine shrimp, benefiting the economy, the food web, and overall health of the lake.
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Reducing Greenhouse Gas Emissions
Recently, a new study has shown the exposed sediments in Great Salt Lake’s dry lakebed are a significant source of global greenhouse gas emissions. Compared to the lake’s aquatic emissions, the lakebed emissions constitute a ~7% increase in emissions, equivalent to 4.1 million tons of carbon dioxide and other greenhouse gases.
Increasing water flows into the lake will not only help Great Salt Lake reach a healthy lake level once more, but will decrease the amount of exposed lakebed, therefore decreasing the lake’s overall contribution to greenhouse gas emissions that are causing the planet to warm.
