The coast is not so clear at California’s Clear Lake.
A satellite image taken by NASA shows the popular tourist destination so overcome by bright green algae that it is visible from space.
The bright swirls seen in the May 15 photo covered most of the freshwater lake, which is located about 120 miles north of San Francisco and is the Golden State’s largest natural freshwater lake — and the oldest lake in North America.
The bloom could pose a threat to marine animals and humans, according to the agency, and officials warn it may affect recreational activities.
Clear Lake is the largest natural freshwater lake in California and the oldest lake in North America — and possibly the world. NASA Earth ObservatoryThe bloom may contain blue-green algae, also known as cyanobacteria, which can produce a potent toxin that can cause skin rashes, eye irritation and respiratory issues.
In extreme and rare cases, it can result in gastroenteritis, liver and kidney failure and even death, according to the Environmental Protection Agency.
Humans are typically exposed by accidental ingestion or inhalation during activities near or on the water.
Clear Lake State Park draws visitors for swimming, fishing, boating and water skiing.
Only a direct sample will determine the exact composition of the lake’s bloom.
Clear Lake, one of California’s oldest and most-visited lakes, is typically blue but an algal bloom has recently turned it cloudy and green. Cam M Poggensee/Wirestock – stock.adobe.comToxicity monitoring done on May 8 did not show the bloom and the next sampling will take place on June 4, the Los Angeles Times reported.
Cyanobacteria is a type of phytoplankton, a floating, plant-like organism that reproduces abundantly with the right nutrients, sunlight and water conditions.
Clear Lake is already a nutrient-rich body of water and humans have recently contributed to an increased number of harmful growths, according to studies.
The lake, which is one of the Golden State’s most visited lakes, once lived up to its name but has grown murkier as a result of nutrients such as phosphorus entering through tributaries, according to the US Geological Survey.
Officials say runoff from nearby farms, vineyards, faulty septic systems, gravel mines and an abandoned open-pit mercury mine are likely to blame.
Waves and nonnative carp also kick up nutrients from the lake bed into the water.
The blooms typically pop up annually and thrive during the summer months.
