Friday, 29 March 2024

Blue-green algae bloom in San Luis Reservoir and O’Neill Forebay; caution urged in water contact

sanluisreservoirmapSACRAMENTO – The Central Valley Regional Water Quality Control Board and the California State Parks are urging swimmers, boaters and recreational users to avoid direct contact with, or use of, waters containing blue-green algae (cyanobacteria) now blooming in San Luis Reservoir and O’Neill Forebay located in Merced County on the western edge of the San Joaquin Valley.

Due to the potential health risks, the San Luis Reservoir and O’Neill Forebay are now posted with health advisories.

Water samples collected by the Department of Water Resources on July 11 and July 25 exceeded the trigger levels for the protection of human health from the California Cyanobacteria and Harmful Algal Bloom Network’s Voluntary Guidance. 

Cyanotoxins in samples from San Luis Reservoir near Dinosaur Point Boat Ramp exceed the danger action trigger and samples from the O-Neill Forebay exceed the caution action trigger.

Samples taken at the O’Neill Forebay North Beach swim area had toxin levels less than the caution action trigger level. However, the public is still urged to use caution when recreating in this area as bloom conditions can change rapidly.

For more information on the status of recreational activities at the San Luis Reservoir and O’Neill Forebay, the public should contact the San Luis Reservoir’s State Parks Service at 209-826-1197.

Officials urge people to choose safe activities when visiting San Luis Reservoir and O’Neill Forebay and recommend that people and their pets avoid contact with water, including swallowing or inhaling water spray, in areas with algae blooms. Children and pets are particularly at risk.

The map above shows the location of the Dinosaur Park Boat Ramp in the San Luis Reservoir where toxin levels tested above the danger action trigger.

Danger signs are posted at this location and water contact recreation is prohibited. The North Beach Swim Area in the O’Neill Forebay has Caution signs posted limiting water contact.

San Luis Reservoir, part of the California State Water Project, provides drinking water to many parts of California.

The State Water Resources Control Board’s Division of Drinking Water is communicating with drinking water systems that pull water from the project, and is not aware of any drinking water impacts from the current algae blooms.

The algae bloom appears bright green in the water and scum or mats that float on the water’s surface have accumulated along the shoreline and boat ramp area in San Luis Reservoir. The blooms also appear as blue-green, white or brown foam.

Recreational exposure to toxic blue-green algae can cause eye irritation, allergic skin rash, mouth ulcers, vomiting, diarrhea, and cold and flu-like symptoms. Liver failure, nerve damage and death have occurred in rare situations where large amounts of contaminated water were directly ingested.

Pets can be especially susceptible since they tend to drink the water and lick their fur after going in the water.

The Statewide Guidance on Cyanobacteria and Harmful Algal Blooms recommends the following for blue-green algae impacted waters:

– Take care that pets and livestock do not drink the water, swim through algae, scums or mats, or lick their fur after going in the water. Rinse pets in clean water to remove algae from fur.
– Avoid wading, swimming, or jet or water skiing in water containing algae blooms or scums or mats.
– Do not drink, cook or wash dishes with untreated surface water from these areas under any circumstances; common water purification techniques (e.g., camping filters, tablets and boiling) do not remove toxins.
– People should not eat mussels or other bivalves collected from these areas. Limit or avoid eating fish from these areas; if fish are consumed, remove guts and liver, and rinse filets in clean drinking water.
– Get medical treatment immediately if you think that you, your pet, or livestock might have been poisoned by blue-green algae toxins. Be sure to alert the medical professional to the possible contact with blue-green algae.

For more information visit the following:

– California Department of Public Health: http://www.cdph.ca.gov/healthinfo/environhealth/water/Pages/Bluegreenalgae.aspx ;

– State Water Resources Control Board - California CyanoHAB Network: http://www.mywaterquality.ca.gov/monitoring_council/cyanohab_network/index.html ;

– California Office of Environmental Health Hazard Assessment, information on microcystin: http://oehha.ca.gov/ecotoxicology/general-info/information-microcystins ;

– US Environmental Protection Agency CyanoHAB Web site: https://www.epa.gov/nutrient-policy-data/cyanohabs ;

– US Environmental Protection Agency, Anatoxin-a report: https://www.epa.gov/sites/production/files/2015-06/documents/anatoxin-a-report-2015.pdf .

072716sanluisreservoiralgage

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