This lake sustains trillions of animals, but it’s drying up

The fragile heartbeat of Mono Lake

In the heart of California’s Eastern Sierra lies a lake that defies the ordinary. Its waters shimmer in shades of blue and silver, sustaining trillions of tiny creatures that fuel one of nature’s most remarkable food webs.

Yet beneath its beauty, this ancient lake faces a silent crisis that threatens life far beyond its shores. What’s causing this natural wonder to fade, and can it be saved before it’s too late?

How Mono Lake was formed and its geology

Mono Lake lies in an “endorheic” basin, which means water flows in but has no river outflow, so evaporation is the only exit. Over hundreds of thousands of years, salts have accumulated, making it highly alkaline.

Beneath the lake surface lie springs that bring fresh water, interacting chemically with lake salts to form tufa towers, limestone spires rising from the water. These tufa formations are both geological monuments and ecological features used by wildlife.

The base of the food web

At the core of the Mono Lake ecosystem are microscopic algae and single-celled plankton that photosynthesize using sunlight. These algae support enormous populations of brine shrimp, sometimes numbering in the trillions in a season.

The shrimp graze algae and convert them into biomass that larger animals can consume. Without a healthy algae base, the entire food web, including birds, would collapse.

Alkali flies and their role in the shore zone

Along the shallow margins of Mono Lake live vast numbers of alkali flies (Ephydra hians). These flies dive underwater in small air bubbles to lay eggs on submerged surfaces and feed on algae and bacteria.

Their larvae later emerge and provide food for birds and other invertebrates. The fly populations are a crucial bridge between aquatic and terrestrial zones.

Migratory birds and the lake as a stopover

Mono Lake is a critical stopover and nesting site for millions of migratory birds, including Wilson’s phalaropes, eared grebes, avocets, and gulls. Birds migrating between the Arctic and South America rely on the lake’s abundant food to fuel long flights.

Some species also nest on islands in the lake. They are taking advantage of predator protection when water levels are high.

No fish, but a simple and robust system

Unlike many lakes, Mono Lake has no native fish because its salinity and alkalinity are too extreme. This absence of fish means the system is simpler: algae, shrimp and flies, and birds.

The simplicity makes it vulnerable: if one link falters, the chain breaks. The lake’s stability depends on maintaining precise balances of water, chemistry, and species abundance.

History of human water diversion

Starting in 1941, the City of Los Angeles diverted freshwater streams that fed Mono Lake through the Los Angeles Aqueduct. Over the decades, these diversions lowered the lake level.

These lower levels exposed more shoreline, increasing salinity, and threatening the ecosystem. By the 1980s, the lake had dropped severely, doubling its salinity and exposing tufa towers and the lakebed.

Legal protections and the Public Trust doctrine

In the 1980s and 1990s, environmental advocates used the Public Trust doctrine. This doctrine states that certain natural resources must be preserved for public use to protect Mono Lake’s water rights.

In 1994, the California State Water Resources Control Board required limits on water diversions. They ended up mandating raising the lake level toward a healthy target.

Current lake level and mandated targets

As of 2025, Mono Lake remains several feet below the mandated healthy level of 6,392 feet above sea level. The lake has recovered somewhat from its lowest historic levels.

However, conservationists stress that it is about halfway short of its required target. The ecosystem continues to show signs of strain.

Trends in bird nesting success

In recent years, biologists have documented dramatic drops in bird nesting success at Mono Lake. In 2024, only 324 gull chicks survived, down from thousands in prior years.

This represented one of the lowest reproductive events ever recorded. The collapse is linked to disruptions in prey availability (shrimp) and anomalous water chemistry.

Effects of meromixis on lake mixing

A concerning trend is that Mono Lake has at times become meromictic, meaning its deep waters no longer mix with the surface layers. This reduces oxygen exchange and nutrient cycling.

This ends up harming deep-water organisms and altering the chemical balance. The shift toward meromixis has been linked to changing water levels and reduced inflows.

Dust, air quality, and human health risks

When water levels fall, the previously submerged lakebed is exposed. Wind can lift dust carrying fine particles and toxic compounds like arsenic, harming local air quality and human health.

Similar problems have been documented at other drying saline lakes. The danger is that dust events can become more frequent and severe as the lake shrinks further.

Broader patterns

Mono Lake’s crisis is not unique. More than half of the world’s large lakes and reservoirs have shrunk since the early 1990s due to climate change.

This has led to water withdrawals and reduced river inflow. The trend threatens ecological, economic, and human systems globally.

Comparison with Great Salt Lake

Another example is Utah’s Great Salt Lake, which has lost 73% of its water and 60% of its surface area in recent years. Because of that, its ability to sustain wildlife is at serious risk.

That lake also faces toxic dust problems when dry beds blow in the wind. The two cases show how saline lakes globally are under stress from similar forces.

Challenges ahead for restoration

One challenge is that more water is being consumed upstream for agriculture, cities, and industries. Second, reduced snowpack and shifting precipitation patterns shrink the natural supply.

Third, political and legal disputes over water rights slow down implementation. Fourth, climate extremes like droughts may overwhelm management plans.

Do you know how climate change in the 1400s emptied Arizona’s ancient great pueblos?

Lessons from other drying lakes

The Aral Sea is a stark example, once one of the world’s largest lakes, it largely dried up due to unsustainable diversion of rivers. Toxic dust from its exposed bed has spread health hazards over vast regions.

Local economies collapsed as fisheries vanished and salinity rose. That case shows how prolonged neglect can make recovery nearly impossible.

Looking at the birght side, these Oregon Hills display 35 Million years of climate history in colorful layers.

Have you ever seen a place so full of life yet on the brink of disappearing? Don’t forget to like and share your thoughts in the comments!

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This slideshow was created with AI assistance and human editing.