Popular US Lake Turning Toxic, Undergoing Startling Change

In an image captured from space, the normally clear waters of Northern California's Clear Lake reveal a striking sight: extensive algae blooms spreading across its surface.

Recorded by NASA's Landsat 9 satellite on May 15, the image displayed vibrant green patches signifying the presence of algae throughout much of the lake, as per information provided on the National Aeronautics and Space Administration website.

The proliferation of algae in the lake is attributed to various substances, including phosphorus and other chemicals, stemming from diverse sources such as nearby farms, vineyards, faulty septic systems, gravel mines, and an abandoned open-pit mercury mine, according to NASA.

Ian Hendy, a senior scientific officer at the Institute of Marine Sciences of the University of Portsmouth in England, remarked on the consequences of excessive nutrients, stating, "These excess nutrients can cause harmful algal blooms. This is a bust or boom scenario whereby blue-green algae, for example, will proliferate and utilize all of the available dissolved oxygen."

The utilization of oxygen by algae leaves insufficient levels for other aquatic life forms, creating perilous conditions. "This process creates very low oxygen levels in the water, making life for aquatic organisms such as fish and invertebrates very dangerous," added Hendy.

NASA issued a warning regarding the potential presence of blue-green algae, also known as cyanobacteria, in the bloom. Certain cyanobacteria produce microcystin, a toxin capable of irritating the skin and causing liver and kidney damage.

Clear Lake, situated approximately 60 miles north of San Francisco Bay and covering an area of 68 square miles, serves as a popular destination for outdoor enthusiasts engaged in activities like boating and fishing, according to the Los Angeles Times. However, the lake has long grappled with recurring algae blooms.

NASA's recent observations indicate a surge in the frequency of these blooms, with the agency noting, "three species of blue-green algae can cause adverse human health effects under certain conditions."

Analyzing the lake, NASA highlighted elevated levels of chlorophyll-a on May 15, suggesting heightened cyanobacteria levels. Nonetheless, NASA cautioned that definitive conclusions require actual water samples.

Even in the absence of toxins, the abundance of algae poses risks to aquatic life, as bacteria consume oxygen during the decomposition of dead phytoplankton, potentially leading to hypoxia and dead zones, NASA cautioned.

The extent of the algae bloom could disrupt recreational activities such as boating, fishing, and swimming at Clear Lake, one of the nation's most-visited lakes, for several weeks, according to the Los Angeles Times.

Although a May 8 assessment did not reveal the presence of the bloom, further testing is scheduled for Tuesday, as reported by the Times.