Largest Freshwater Lake in California Turns Green Due to Huge Algal Bloom, NASA Image Reveals

Photos taken on the Landsat 9 satellite's OLI-2 (Operational Land Imager) last May 15 show that California's Clear Lake has a bright green color due to algal blooms.

For a long time, Clear Lake has been plagued by grave algal blooms that pose health and environmental concerns.

Clear Lake: California's Largest Freshwater Lake

Clear Lake is North America's oldest lake, being roughly 500,000 years old. It covers roughly 68 square miles.

Huge populations of fish are supported by the lake, while several bird species also get attracted to it. This makes it a hotspot for enthusiasts of wildlife.

Algal blooms regularly take place in the lake, as the shallow depths and warm waters make it an ideal spot for algae to breed.

Algal Blooms in Clear Lake

The algal blooms within this freshwater lake are mainly caused by cyanobacteria or blue-green algae. Such single-celled organisms can thrive in environments that are rich in nutrients, especially when nitrogen and phosphorus are abundant.

Such surplus nutrients could lead to HABs (harmful algal blooms). This is a boom or bust scenario wherein cyanobacteria, for instance, could proliferate and make use of all the dissolved oxygen that is available. This was explained by senior scientific officer Ian Hendy from the Institute of Marine Sciences of the University of Portsmouth.

Agricultural runoff and other activities of humans, such as sewage treatment and mining, usually exacerbates the issue. Such matters can increase nutrient levels within the water, triggering more regular and severe blooms.

Last May 15, which was when the photo was taken, it was found that chlorophyll-a levels went up to some of this month's highest levels in Clear Lake. Chlorophyll-a is a chemical that plants and algae use to harvest light energy.

More than 130 algae species have been picked up in Clear Lake's water. Three of these species could be harmful to the health of humans.

Based on a statement of the NASA Earth Observatory, some of Clear Lake's algae could produce some toxins, such as microcystin. This could end up posing grave health risks to wildlife and humans.

Microcystin could trigger liver damage, skin irritation, and even kidney failure.

Even when the toxins are not present, the algal blooms could get energy from the water. They may potentially lead to the asphyxiation of fish and other life forms.

Hendy explained that such a process results in extremely low levels of oxygen in the water. This would make life for marine organisms extremely dangerous.

There are vital recreational and ecological implications that come with Clear Lake's algal blooms. Tourists and residents are also advised to not engage in water activities due to their health risks. Moreover, the visual effect of the blooms end up deterring visitors, which could resultantly affect tourism and the economy.

Clear Lake's situation stresses the greater environmental challenges brought about by climate change and nutrient pollution. With the increase of nutrient levels and warming of water bodies, the severity and frequency of algal blooms could go up. This could necessitate efforts to protect public health and water quality.

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