The Wilson’s phalarope, a small migratory shorebird that depends on the Great Salt Lake as a refueling stop during its annual journey between North and South America, is running out of food and habitat as the lake shrinks to historic lows. In November 2022, the lake’s average daily elevation dropped to 4,188.5 feet at the South Arm Causeway gauge, more than 11 feet below the historic average of roughly 4,200 feet. That collapse in water volume is driving salinity higher, killing off the algae and invertebrates the phalarope needs to survive, and raising the prospect that the species could face an Endangered Species Act listing petition if conditions do not reverse.
How record-low lake levels are starving shorebird colonies
The Great Salt Lake’s decline is not a slow drift. It is a sharp contraction that hit record-low volume in 2022, according to peer-reviewed research published in Geophysical Research Letters. That study attributed the collapse to a combination of anomalously low streamflow and persistent evaporation losses over multiple years. Agricultural diversions upstream have steadily reduced the freshwater inflows the lake needs to maintain its size, and prolonged drought across the Great Basin has compounded the problem.
Every foot the lake loses concentrates its salt content. The relationship between elevation and salinity is well documented by the USGS monitoring platform, which tracks real-time conditions across both the north and south arms of the lake. As the water surface drops, the lake’s brine becomes too salty for the organisms at the base of the food web. Brine flies and brine shrimp, the two primary food sources for migrating shorebirds including the Wilson’s phalarope, cannot reproduce effectively when salinity climbs past certain thresholds. The result is a collapsing food supply at exactly the site where hundreds of thousands of phalaropes historically gathered each summer to build fat reserves before flying to South America.
The state water agency recorded the 4,188.5-foot low at the South Arm Causeway gauge, placing it well below the historic average near 4,200 feet. At that average elevation, the lake covers a vast area of shallow, productive water. At 4,188.5 feet, large sections of lakebed are exposed, and the remaining water is far saltier and far less hospitable to invertebrate life.
Salinity data and the deep brine layer since 1966
A peer-reviewed synthesis published in the journal Water examined long-term salinity conditions from 1966 through the early 2020s, establishing a detailed record of how the lake’s deep brine layer responds to changes in elevation and inflow. The deep brine layer sits beneath the upper water column and acts as a kind of chemical boundary. When the lake is healthy and receiving adequate freshwater, that boundary stays relatively stable, and salinity in the upper layer remains within the range that supports biological productivity. When inflows drop and the lake shrinks, the chemistry shifts. Salinity rises in the upper layer, and the deep brine layer can expand or migrate, disrupting the conditions that algae and invertebrates need.
This matters for the Wilson’s phalarope because the bird’s entire migration strategy depends on the Great Salt Lake producing enormous quantities of brine flies and brine shrimp during the summer months. The phalarope is a specialist. It does not have many alternative stopover sites with comparable food density. If the lake’s invertebrate populations crash because salinity has climbed too high, the birds arrive to empty water and cannot gain the weight they need for the next leg of their journey. Over successive years of poor conditions, population-level declines become likely.
The hypothesis that a sustained recovery in lake elevation above roughly 4,195 feet for several consecutive years could push salinity back below levels that support invertebrate rebound is grounded in the elevation-salinity relationship documented by USGS monitoring data. But that recovery requires a significant and sustained increase in freshwater inflows, which current streamflow records do not yet show. Without that water, the deep brine chemistry remains hostile to the organisms shorebirds eat.
The ESA petition and what scientists still do not know
The legal dimension of this crisis centers on a petition to list the Wilson’s phalarope under the Endangered Species Act. The S.J. Quinney College of Law has outlined the mechanics of that petition, explaining that ESA listing would trigger federal protections for the species and potentially force changes in how water is allocated in the Great Salt Lake basin. The petition rests on whether the food-web disruptions caused by the lake’s decline are severe enough and persistent enough to threaten the phalarope’s long-term viability as a species.
Several questions remain unanswered for scientists and regulators evaluating that risk. One is how quickly invertebrate populations could rebound if lake levels were restored. The long-term salinity record shows that the system can shift between relatively fresh and hypersaline states, but it is less clear whether brine shrimp and brine flies can recover at the same pace after prolonged stress. Another uncertainty is how much flexibility the phalarope has in its migratory behavior. Some individuals may be able to use alternative wetlands in the interior West or along the Pacific coast, yet there is little evidence that any other site currently offers the same combination of area and food density that the Great Salt Lake once provided.
Researchers are also still piecing together how changes in the deep brine layer propagate through the food web. The chemistry of that layer affects nutrient cycling, oxygen availability, and the vertical distribution of algae. Small shifts can cascade into large changes in primary productivity, but the thresholds at which those cascades occur are only roughly constrained by existing data. This scientific uncertainty complicates efforts to set precise management targets. Managers can say with confidence that higher lake levels and lower salinity will help, but they cannot yet guarantee that a particular elevation will produce a specific biological response in a specific year.
What recovery would look like for birds and the lake
Despite the grim trends, the same research that documents the lake’s decline also points to a path for recovery. Because the Great Salt Lake is a terminal basin, nearly every additional acre-foot of water that reaches it and is not diverted upstream contributes directly to higher elevations. Model results from hydrologists suggest that sustained reductions in consumptive use, combined with wetter years, could push the lake back toward the mid-4,190-foot range over time. In that scenario, salinity in the upper water column would likely drop, the deep brine layer would contract, and conditions for algae and invertebrates would improve.
For Wilson’s phalaropes, a successful recovery would be visible in the form of dense swarms of brine flies along the shorelines and robust summer populations of brine shrimp in the open water. Birds arriving from breeding grounds would encounter a buffet instead of a biological desert, allowing them to double their body weight before departing for South America. Banding and tracking studies could then confirm whether survival rates during migration and on the wintering grounds improve as lake conditions stabilize.
Whether that future materializes depends on policy choices being made now. The Endangered Species Act petition has raised the stakes, but it does not by itself deliver more water to the lake. That will require negotiated changes in water rights, conservation programs that reduce agricultural and urban demand, and careful management of any new development in the basin. Scientists stress that time is a critical factor: the longer the lake remains at very low elevations, the more likely it is that parts of the ecosystem will cross thresholds that are difficult or impossible to reverse.
The fate of the Wilson’s phalarope has become a powerful symbol of this broader ecological gamble. A bird that weighs less than a deck of cards cannot, by itself, change the trajectory of western water management. But its dependence on a functioning Great Salt Lake has clarified how intimately tied the region’s wildlife is to decisions about rivers, reservoirs, and fields hundreds of miles upstream. In that sense, the phalarope is both a victim of the lake’s decline and a messenger, signaling how much is at stake if the water does not return.
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*This article was researched with the help of AI, with human editors creating the final content.
