Here’s what ‘thousands of floating eggs’ look like on Utah’s Great Salt Lake

An aerial view shows a swirl of light brown on Great Salt Lake.
Utah’s Great Salt Lake Park shared photos of floating brine shrimp egg clusters, which start to resemble thick pools of chocolate milk the closer they get to shore.
(Utah State Parks via Tribune News Service)

A thick, chocolaty sludge has formed on Utah’s Great Salt Lake, and state parks officials say talk of an oil slick is unfounded.

It’s actually more gooey and disgusting than that.

What’s floating atop the lake is “trillions” of brine shrimp eggs, technically called cysts, according to Great Salt Lake State Park & Marina. The park is just northwest of Salt Lake City.

“In good conditions, these cysts will come together and form a ‘slick,’ ” the park wrote Friday on Facebook. “These will look like an oil slick in the water, hence the name, but if you look closely you will see thousands of floating eggs.”


Low temperatures cause brine shrimp to produce dormant eggs, which are commercially “harvested as food for fish and commercially grown shrimp,” the state says.

The Great Salt Lake Park shared multiple photos of the floating egg clusters, which start to resemble thick pools of chocolate milk the closer they get to shore.

At 75 miles in length, Great Salt Lake is “the largest lake west of the Mississippi River” and “one of the saltiest bodies of water in the world,” the state says. It is fed by four rivers but has no outlet, so the water sits until it evaporates, making it heavy with minerals, the state says.

Brine shrimp is one of the few species that can live in the water, but even they cannot survive when it gets cold, officials say.

“In the fall brine shrimp lay trillions of eggs that float on the surface of the lake until spring when it is warm enough to hatch. The eggs are so small that 150 eggs can fit on the head of a pin,” the state says. “Dried brine shrimp eggs can lay dormant for many years and hatch when placed in salt water.”