Toxic Blue-Green Algae Closes Second SoCal Lake

First Pyramid Lake, a popular location an hour northwest of the city, was closed due to a toxic algae bloom that colored the waters bright green. Pyramid reopened last week after a ten-day closure, but now state water officials have issued an advisory for a second Southern California lake, warning potential visitors to stay out of the water at San Bernardino County's Silverwood Lake until further notice. CBS LA reports that as of Thursday, the lake above Crestline will be closed to all water activities so that officials can treat the bloom.

Blue-green algae, or cyanobacteria, are a kind of photosynthetic microscopic bacteria that occur naturally in surface waters, according to the California Department of Public Health. A number of conditions can lead them to multiply into a toxic bloom, particularly in summer months when temperatures are warmer, lake levels are low, and waters are mostly stagnant. Exposure to the slimy blooms can pose risks to humans, pets, livestock and wildlife. Kids are especially vulnerable, as their small body weight means their exposure to the toxins will be higher than adults, given the same volume of water intake. At least three people were sickened from the waters at Pyramid Lake. Similar advisories have also been issued this summer for the San Luis Reservoir in Merced County and Shasta Lake in Northern California, according to the San Bernardino Sun.

The San Gabriel Valley Tribune published an investigation into the growing presence of cyanobacteria in June. After analyzing water testing data from various agencies they found that toxin levels across California exceeded the proposed thresholds in more than 100 lakes, reservoirs and streams in at least 36 counties, including Los Angeles, San Bernardino, Riverside and Orange, between 2011 and 2015.