SAN FRANCISCO (CBS SF) -- An increase of blue-green algae blooms in California due to fertilizer runoff -- exacerbated by the drought -- has decreased fresh water swimming options for Californians trying to cool off this summer.
In mid-August, health officials urged recreational water users to avoid direct contact with yet another California body of water, the Mountain Meadows Reservoir in Lassen County.
While the cause of the Mountain Meadows Reservoir algae bloom remains unknown, other toxic algae blooms across California have been linked to fertilizer runoff.
The Central Valley Regional Water Quality Control Board said the water at Mountain Meadows Reservoir contains blue-green algae, or cyanobacteria, and that "Recreational exposure to toxic blue-green algae can cause eye irritation, allergic skin rash, mouth ulcers, vomiting, diarrhea, and cold and flu-like symptoms. Pets can be especially susceptible because they tend to drink while in the water and lick their fur after."
Cyanobacteria was identified there and can produce toxins, but health officials said the presence of toxins has not been confirmed at Mountain Meadows Reservoir.
A Central Valley Regional Water Quality Control Board employee, when asked by CBS San Francisco for nutrient levels of the water, said that due to funding limitations, crews are only testing for the presence of toxins, not nitrate or phosphate levels -- high levels of which cause algae blooms.
A 2007 report on the Mountain Meadows Reservoir by the Stewardship Council, a California nonprofit public benefit corporation, notes that the surrounding lands were being used for timber production, hydropower, grazing, and rock mining. It also stated that PG&E, which operates a hydropower project on the reservoir, "has previously leased grazing rights for the upland parts of the meadow on the northern shore, but the leases have not been renewed in recent years."
The 2007 report, which doesn't account for the recent drought, states that Mountain Meadows Reservoir is shallow and warm, and therefore has a higher potential for being nutrient-rich. High e. coli bacteria counts were previously reported in the reservoir, "which may derive from upstream cattle grazing, migratory waterfowl, or the adjacent sewer ponds for the town of Westwood," the report states.
The long-term effects of cattle grazing on surrounding lands, which can contribute to increases in nutrients in the water, has not been determined.
The bloom may also be linked to last fall's sudden drainage of the lake, which killed thousands of fish. When aquatic plants and fish die and decompose, it increases the phosphorus and nitrogen levels in the water.
In Contra Costa County, health officials are dealing with a blue-green algae emergency.
A U.S. Environmental Protection Agency lab in Richmond confirmed the presence in Discovery Bay of the toxin, microcystin, which is produced by cyanobacteria.
Health officials are urging people not to go in the water in Discovery Bay but say drinking water has not been impacted.
Contra Costa County Health Services officials said earlier this month, when the bloom was initially detected, "The best way to reduce and prevent blooms is to reduce water pollution, particularly from runoff containing fertilizers or pesticides."
In California's Central Valley, one of the world's most productive agricultural regions, green-blue algae blooms are growing and have been linked to fertilizer runoff and the ongoing drought, which has caused waterways to warm, providing a hospitable environment for cyanobacteria.
Already this summer, the Central Valley Regional Water Quality Control Board has issued warnings for swimmers and recreational water users to avoid the waters of the San Luis Reservoir, after water tested there exceeded safe levels for human health.
San Luis Reservoir is part of the California State Water Project and provides drinking water to many parts of California. State officials said they are not aware of any drinking water impacted by the current algae blooms in the reservoir and are working to ensure that water from the reservoir doesn't end up in tap water.
The link between fertilizers and toxic blue-green algae has been well-documented by scientists as well as California government agencies.
A factsheet by the Office of Environmental Health Hazard Assessment, dating back to 2009, states, "Any efforts to prevent nutrients from running off of lawns, pastures, or agricultural fields will reduce the frequency and severity of toxic blue-green algae blooms as well as other types of nuisance blooms...Agriculturalists can play a major role in reducing BGA blooms by also carefully controlling the use of fertilizers." The fact sheet goes on to explain that toxins produced by cyanobacteria thrive when phosphorus levels rise.
Hans W. Paerl, Ph. D., Professor of Marine and Environmental Sciences at the University of North Carolina-Chapel Hill, studies cyanobacterial algal blooms and states, in a 2011 study, that loading of nitrogen and/or phosphorus to water bodies from agricultural, industrial and urban sources influences the development of these algal blooms and may be related to cyanotoxin production.
The Russian River in Sonoma County also has sections with blue-green algae blooms this summer. And while there are not yet any restrictions on human recreational use of the Russian River, the public is being advised that "potentially harmful algae may be present" and that children and pets should be kept from playing in the algae and prevented from drinking river water.
According to 2012 water testing results posted on the U.S. Environmental Protection Agency's website, the Russian River has been impaired by high levels of phosphorus, a key element in agricultural fertilizers.
U.S. Environmental Protection Agency water tests from 2012 show that high levels of phosphorus and nitrogen are also impairing Lake Tahoe, causing algae to bloom there too.
Among the waterways around California that swimmers are being urged to avoid or to limit contact with this summer are all or parts of O'Neill Forebay, the Pit River arm of Shasta Lake, Lake Britton, Copco and Iron Gate Reservoirs on the Klamath River.
By Hannah Albarazi - Follow her on Twitter: @hannahalbarazi.
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