GREAT SALT LAKE
What Great Salt Lake is
A terminal lake with no outlet, split in half by a railway, holding a hemispheric bird population on the backs of two animals and a reef made of microbes.
A Union Pacific rail causeway runs east to west across the middle of Great Salt Lake. It has been there since the late 1950s, it is nearly solid, and it has split the lake into two bodies of water that no longer mix freely.
The consequence is that the north and south arms sit at different elevations and very different salinities. There are two federal gauges because there have to be two: 10010000 at Saltair on the south arm, reporting daily since 18 October 1847, and 10010100 near Saline on the north arm, reporting since 1966 .
Flow between the two is managed through a breach in the causeway with a berm in it, which the state raises and lowers to control how much dense north arm brine moves south. That berm is the single most consequential piece of plumbing on this lake and it is barely known outside the agencies.
In January 2024 the Office of the Great Salt Lake Commissioner , created by the legislature in 2023, published a strategic plan that set out what elevation the lake needs. It defines a minimum healthy elevation of 4,198 feet and bands underneath it :
| Band | Elevation |
|---|---|
| Healthy range | 4,198 to 4,205 ft |
| Transitionary | 4,195 to 4,198 ft |
| Adverse effects | 4,192 to 4,195 ft |
| Serious adverse effects | Below 4,192 ft |
One disagreement worth printing. The commissioner's plan gives the healthy range as 4,198 to 4,205 feet . The Great Salt Lake Strike Team's January 2026 summary gives it as 4,198 to 4,202 . The minimum is the same in both. The ceiling is not.
- Record high, 4,211.65 ft, June 1986 . The lake covered about 3,300 square miles. It had risen roughly twelve vertical feet in five years, including a rise of 5.2 feet between 18 September 1982 and 30 June 1983, which the federal survey records as record breaking .
- Record low, 4,188.5 ft, 7 November 2022 . The previous record low was 4,191.35 ft in October 1963, so 2022 did not edge the old mark, it took nearly three feet off it.
That is a twenty three foot range in a single human lifetime, on a lake so flat that a foot of elevation moves the shoreline a long way. It is why a marina built for this lake has had to be dredged twice, and why a sculpture built on the shore in 1970 spent decades underwater and is now a long walk from the water .
Great Salt Lake is what is left of Lake Bonneville, a freshwater lake that covered much of western Utah in the last ice age and drained catastrophically. The terraces cut by its old shorelines are still legible on the mountain fronts above Salt Lake City if you know to look for them.
Because it is a terminal lake with no outlet, everything the rivers carry in stays in. That is the entire explanation for the salt, and it is also the reason the lake concentrates whatever else arrives with the water.
The lake bed is not a natural desert. It is lake bottom that used to be under water, which is a different thing, and it is the reason the dust question exists at all.
The level, and the dust
One chart explains most of this lake. The dust question underneath it is the one most often reported wrongly, so all three bodies of evidence are printed with their methods.
This is the most contested thing about Great Salt Lake and the place where reporting most often goes wrong. There are three separate bodies of evidence and they are not measuring the same thing.
| Who | What they measured | What they found |
|---|---|---|
| Utah air quality division | Metals in PM10 on regulatory filters at fixed monitors, five urban sites 2022 to 2023, seven lake sites 2023 to 2025 | Concentrations of all metals below established levels of concern, and no increase in arsenic or other toxic metals over recent decades |
| Federal geological survey | Passive bulk dust samplers, 17 sites, autumn 2022, eleven priority pollutant metals | Highest dust fluxes near the playa. Thallium, arsenic, lead, cobalt and chromium contributed most to a calculated health hazard, with young children most vulnerable |
| University researchers | Lakebed sediment, not air | Arsenic 0.18 to 118.89 micrograms per gram dry mass, benchmarked against sediment guidelines written to protect aquatic organisms |
What the state air agency says about its own limits is equally important and equally omitted: it states plainly that it does not yet know whether playa metals are being lifted into the air and carried to residential areas, and that not all dust reaching the Wasatch Front is lake dust .
Between 2023 and 2025 there were four exceedances of the federal PM10 standard across the monitoring network, at three stations .
None of that makes the dust question settled or harmless. It makes it open. A page that prints only the sediment number is scaremongering, and a page that prints only the regulatory filters is a press release. All three rows are above, with the method named on each.
Two active federal gauges, one per arm . Both publish parameter 62614, which is elevation above the 1929 datum, not the 1988 one . That distinction matters because the federal elevation to area and volume tables for this lake are published on the 1988 datum, so the two sets of numbers are not directly comparable without a conversion.
Every elevation on this page is on the 1929 datum, because that is what the gauges report.
The south arm daily record runs back to 18 October 1847, which makes it one of the longest continuous water records in the western United States. The north arm record starts in 1966, after the causeway had already split the lake.
The shoreline drawn at the top is traced from OpenStreetMap , which is not an agency. On a terminal lake that has moved twenty three vertical feet inside a lifetime, no single outline is correct for long, and a shoreline captured at one elevation will be wrong at another.
Treat it as the shape of the lake, not the position of the water. The federal survey publishes elevation to area relationships precisely because the area is a function of the level rather than a fixed property .
Federal identifiers, if you want to pull the water body yourself: the lake carries a Geographic Names Information System feature record and a National Hydrography Dataset polygon, both queryable from the same national map service . Its published area is a snapshot like any other outline of this lake.
What lives in it
No fish. Three links in a chain, and ten million birds standing on the end of it.
Microbialites
The reefs on the lakebed. Mounds built by microbes, and the base the whole thing stands on. They were exposed and bleached when the lake dropped .
Brine shrimp and brine flies
The only two animals abundant in the open water. Brine shrimp tolerate roughly 30 to 330 grams of salt per litre, which is three to thirty three percent . Utah runs a certified brine shrimp cyst harvest on them.
Ten million birds
Eared grebes, Wilson's phalaropes, avocets, stilts and the largest California gull colonies anywhere. They are here because the two animals above are here .
Artemia franciscana is the only recognised brine shrimp species in the lake. Adults run about a third to half an inch. They tolerate roughly 30 to 330 grams of salt per litre, which is three to thirty three percent, and that range is why they can live here and almost nothing else can .
What is harvested is not the shrimp but the cysts, the dormant eggs that float in windrows on the surface in autumn and winter. Utah runs it as a certified fishery through the wildlife division's Great Salt Lake Ecosystem Program . The cysts are sold as feed for prawn and fish aquaculture, and a large share of the world supply comes off this lake.
Microbialites are mounds built by microbial communities over thousands of years, and they cover a large share of the lakebed. They are the primary productivity engine here: the photosynthetic mats on them are what the brine shrimp and brine flies graze .
When the lake dropped, they came out of the water and bleached. That is the mechanism by which a falling lake level reaches the birds: it is not that the birds run out of water, it is that the reefs at the bottom of the food chain are exposed and stop producing.
They are visible and walkable at Bridger Bay on Antelope Island, which the state geological survey publishes as a geosite .
Great Salt Lake is a staging ground on a continental flyway, not a local pond with birds on it. The concentrations that matter are eared grebes, Wilson's phalaropes, American avocets, black necked stilts and California gulls, and the reason they are here in those numbers is the two animals in the open water .
The freshwater end of it matters as much as the salt. The Bear River delta at the north of the lake is a federal migratory bird refuge with a visitor centre and an auto tour route, and it is where the fresh water arrives before it becomes salt water .
This page does not print a single total bird count. Several are in circulation, they are counted by different methods over different seasons, and no one agency publishes a figure that all the others use.
Getting to it
Antelope Island for most people, a marina that has been dredged twice, and a sculpture that is now a long way from the water.
| Fee | 2026 |
|---|---|
| Day use, vehicle up to 8 people | 15 dollars |
| Senior 65 and over, vehicle | 10 dollars |
| Motorcycle | 5 dollars |
| Bicycle or on foot | 3 dollars a person |
| Antelope Island annual pass | 65 dollars, causeway fee included |
| State parks annual pass | 125 dollars resident, and it does not cover the Davis County causeway fee. That sticker is a separate 15 dollars |
| Bridger Bay campground, 64 sites | 30 dollars, or 40 with water and power |
| White Rock Bay campground, 20 sites | 40 dollars, covers two vehicles |
Park hours are 6am to 10pm daily, with facilities closed at Thanksgiving and Christmas . No agency publishes a centre point for the island itself, so the map pin for it comes from a secondary source and is labelled as one .
Great Salt Lake State Park sits at Saltair on the south shore, next to the gauge that produces every elevation figure in the news . Its marina has been dredged twice because the lake kept retreating from it.
The first dredge was approved in 2015 at about 1.5 million dollars, delayed as the lake kept falling, and carried out in 2017 and 2018 by suction dredging that proved ineffective because the brine destroyed the equipment. A second dredge began in August 2025 at roughly 4.5 million dollars, with the state aiming to reopen the marina when water levels allowed.
Robert Smithson built Spiral Jetty out at Rozel Point on the north arm in April 1970, from something in the order of six thousand tons of rock and earth . It was underwater for most of the following three decades and it is now well clear of the water.
It is on the north arm, the hypersaline half, which is why the water beside it is often pink. That colour is halophilic microorganisms, and it is a salinity signal rather than pollution.
The published coordinate for the jetty carries four decimal places, so the fifth digit on the map pin for it is a zero rather than measured precision. It is also a long way down unpaved road from anywhere.
What to watch for
Mud that holds until it does not, no water, no shade, and a dust question that is open rather than settled.
A falling lake leaves miles of exposed lakebed that looks walkable and is not. It is saturated silt with a dry crust on top, and the crust carries weight until it does not. People and vehicles get stuck out there every year, a long way from a road, in full sun, with no shade and nothing to push against.
The distances are the danger rather than the depth. If you are a mile out on the flats and stuck to the knees, nobody can see you from the shore and there is nothing to walk to.
- There is no drinking water on the flats or at most access points. Carry more than you think.
- No shade at all. The exposed bed is white and it reflects.
- Brine will destroy gear. It ate a suction dredge . It will do the same to bearings, zips and anything chromed.
- Mobile coverage on the west side and out at Rozel Point is unreliable.
The lake is hypersaline. It stings cuts and eyes and it is unpleasant to swallow, and its salinity is the reason it holds almost nothing that can hurt you biologically. The brine flies that swarm the shoreline in season do not bite.
On dust, the honest position is the one in the science section above: the state air agency measured metals in filtered dust and found them below levels of concern, and states plainly that it does not yet know whether playa metals are reaching residential areas . A federal study using different methods calculated possible hazards from arsenic and other metals with playa attribution . The very high arsenic figures in circulation are lakebed mud, not air .
The lake has not reached the elevation the state itself calls healthy since 2012.
Fathom Restoration is a Utah 501(c)(3) that runs volunteer dive cleanups and is built to pull what does not belong out of Utah water, statewide.
Donate to Protect Great Salt LakeEvery figure on this page is quoted from the source named beside it.
Sources
How these were checked
Every figure is quoted from the sentence or the database field it appears in. Numbered sources are agencies. Lettered sources are everything else, and the most important of them is source A, a university study that measured arsenic in lakebed mud and is routinely quoted as though it measured air. Where agencies disagree, all of them are printed. On this page that happens over the top of the healthy range, over what the dust actually contains, and over which datum an elevation is on.What these numbers are measuring
Two gauges, because there are two lakes. The causeway split this lake into arms that no longer mix freely, and they sit at different elevations. South arm is USGS 10010000 at Saltair . North arm is USGS 10010100 near Saline .
The datum matters more here than anywhere else in this series. Both gauges publish parameter 62614, which is elevation above the 1929 datum . The federal elevation to area and volume tables for this lake are published on the 1988 datum. Numbers from the two cannot be compared without converting, and mixing them is an easy way to be several feet wrong.
The below healthy card is arithmetic on the south arm reading, against the 4,198 foot minimum in the state strategic plan . It is not a measurement.
There is no live salinity. Salinity on the north arm exists as 135 discrete samples between 1998 and 2022, not as a continuous series . Nobody publishes how salty this lake is today.