Toxic algae bloom in Nevada’s Pyramid Lake – Earth seen from space

This impressive satellite photo shows extremely dense, toxic algae swirling in the waters of Nevada’s Pyramid Lake. Some experts believe this algae has been present in the lake for at least 9,000 years.

Pyramid Lake is an approximately 453 square kilometer (175 square mile) lake located northeast of Reno. It is approximately 43 km in diameter at its widest point and is named for the large pyramid-like rock formation on a small island in the southern half of the lake.

A single river flows into the lake, but it is permeable and has no outflow. As a result, it has a higher salinity than most lakes, as the excess water evaporates leaving behind dissolved salt. The lake is also slightly alkaline, with a pH of around 9, which is roughly equivalent to baking soda.

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Pyramid Lake experiences algae blooms each September and October due to rising temperatures and increased nutrient availability. The main algal species is Nodularia spumigena, a blue-green nitrogen-fixing cyanobacteria that thrives in salty water, according to NASA’s Earth Observatory.

But the 2024 bloom captured in this satellite image was one of the most extreme in recent memory. It reached its peak on October 15th, about a week after this photo was taken. It is currently unknown why this flowering is so intense.

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N. spumigena can produce toxins such as nodularin, which can affect the liver and cause adverse health effects in humans and other animals. Local authorities have warned people to keep their pets away from water during the 2024 bloom.

Pyramid Lake was once part of a much larger prehistoric body of water known as Lake Lahontan, approximately 8,000 square miles (21,000 square kilometers), approximately 45 times the size of Pyramid Lake.

This ancient lake suffered from climate change at the end of the last ice age, or Pleistocene, which ended about 12,000 years ago. After about 3,000 years, Lahontan virtually disappeared, leaving Pyramid Lake as its largest ruin.

Today, Pyramid Lake is known for a series of striking columnar calcium carbonate formations known as tufas that grew from the receding waters of Lake Lahontan between 26,000 and 13,000 years ago, according to the U.S. Geological Survey. (This includes the pyramid-like structure that gives the lake its name.)

A 1990 study analyzed N. spumigena bloom trends during 15 consecutive outbreaks in Pyramid Lake between 1972 and 1986. Researchers theorized that cyanobacteria once bloomed in Lake Lahontan and may have persisted in the remaining waters ever since.

Pyramid Lake is also home to the endangered suckerfish, the cuiwi (Chasmistes cujus), which is found nowhere else on earth. These fish primarily feed on algae such as N. spumigena, and are thought to have once lived in Lake Lahontan.