Cyanobacteria Harmful Algae Blooms (CyanoHABs) and Recreational Advisories
What are cyanobacteria?
Cyanobacteria aren't actually algae—they're primitive bacteria found naturally in fresh and salt water worldwide. These bacteria are important because they've helped create and sustin the earth's oxygen atmosphere. In warm weather with plenty of nutrients, cyanobacteria can multiply rapidly, forming what's known as a bloom. Some blooms can produce cyanotoxins, which may be harmful to people and pets.
Why is it called cyanobacteria?
The word "cyan" means blue-green, which is an appropriate name since most
blooms are blue-green or green in color.
Why are these cyanobacteria blooms a health concern?
Not all blooms are harmful, but some cyanobacteria can produce cyanotoxins that can cause serious illness or death in pets, livestock and wildlife. These toxins can also make people sick, and in sensitive individuals also cause a red, raised rash or skin, ear and eye irritation.
What toxins are found in these blooms?
The most common toxins in harmful algal blooms in Oregon are microcystins and cylindrospermopsin, however anatoxin-a and saxitoxin have also been detected.
How can I be exposed?
Exposure occurs when you swallow or inhale water with cyanotoxins during recreational activity, or when using affected water for drinking or cooking. Cyanotoxins are not absorbed through the skin, however, a red, raised rash or irritation of the skin and eyes can develop after contact with a bloom.
What are the symptoms of exposure?
If enough water is swallowed or inhaled you may experience one or more symptoms that mimic food poisoning; headaches, cramps, diarrhea, nausea and vomiting, numbness, dizziness, fever. Children and pets are at increased risk of exposure because of their size and level of activity. Symptoms generally begin within 24 hours and last 72 hours.
When should I seek advice from a health provider or veterinarian?
If you have severe diarrhea, vomiting, skin irritation or other related symptoms, or you experience these symptoms for more than 72 hours, you should seek medical attention to prevent severe dehydration or other problems. People with ongoing liver or kidney conditions should seek medical evaluation if they think their condition is worsening. Although it may be difficult to know if symptoms are related to cyanotoxin exposure, persistent symptoms should not be ignored.
Dogs may exhibit symptoms within the first hour of exposure. Because dogs are susceptible to these toxins at extremely low levels it is very important to get your pet to a veterinarian as soon as possible if they show signs of diarrhea, vomiting, breathing problems, difficulty walking or standing, or loss of appetite. If your dog has been exposed to cyanotoxins, you can contact OHA to have a urine sample submitted for cyanotoxin testing.
Reports of animal illness can be submitted directly to OHA.
Are there treatments available if someone gets sick from a cyanotoxin exposure?
There are no antidotes for cyanotoxins. Health care providers can ease some symptoms to make you more comfortable. If you experience prolonged symptoms, drink plenty of fluids to help avoid dehydration. When seeking medical attention, let your health care provider know that you may have been exposed to cyanotoxins from a bloom, and
submit a human illness report to OHA.
What does a bloom look like?
A bloom’s appearance can change over the course of its life, and different types of cyanobacteria can begin to grow once an initial bloom begins to die. Therefore, it is very important to continue visually monitoring a bloom. There are two main types of cyanobacteria blooms, planktonic (in the water) and benthic (attached to rocks and sand).
Planktonic blooms can look foamy, scummy or thick like paint and are often green, blue-green, pea green, brownish red, or white in color. Sometimes cells can be suspended in the water column, making it look bright green without a layer of visible scum. It can also have the appearance of spilled paint.
Benthic cyanobacteria are attached to the bottom of the lake or river, often to rocks or sand. They form "mats" that can be green, blue-green, or brownish red. They are sometimes in waterbodies where the water looks otherwise looks clear. Benthic mat material can detach from the rocks or sand and float in the water or accumlate and dry along the shore.
When are recreational use health advisories issued?
A recreational use advisory is issued when cyanotoxins have been confirmed through testing and are above Oregon Health Authority's recreational use values (RUVs), or a bloom has been sighted and water will be sampled within 1 business day. OHA has established RUVs for people and dogs, but advisories are only issued in relation to human health concerns, not dog health concerns. You should know that even if an advisory is not in place on a water body, a bloom and toxins can still be present, and may be harmful to your pet. Dogs are extremely susceptible at very low levels and exposure could result in death. If your pet exhibits any unusual symptoms after being in a water body you should seek advice from a veterinarian as soon as possible.
What is the difference between a recreational use public health "advisory" and "precaution"?
An advisory is issued when cyanotoxins have been confirmed through testing and are at unsafe levels, or a bloom has been sighted and water will be sampled within 1 business day. An advisory is lifted when water testing shows safe levels. CyanoHAB advisories are posted to OHA's website, are accompanied by a press release, and are added to the list of advisories on the cyanoHAB hotline voice recording (877-290-6767).
In the absence of immediately available toxin data, a precaution may be issued. CyanoHAB precautions are put in place with lower confidence that hazardous conditions are present and when all the following criteria are met: photos sent to OHA or satellite data are deemed to represent a possible cyanoHAB, the site is known to have public recreational or occupational contact with water, and immediate (<1 business day) water quality testing is unavailable due to resource limitations, remoteness, etc. A precaution is lifted when testing shows cyanotoxin levels are safe, or when the bloom is visibly gone. CyanoHAB precautions are posted to OHA's website and are added to the hotline recording, though are not accompanied by a press release.
How will I know if a bloom is toxic?
Unfortunately, you can't tell if a bloom is producing toxins just by looking at it. Nor is the size of the bloom associated with the amount of toxins a bloom may be producing. Because we don't know why or when cyanobacteria produce toxins, it's impossible to predict when toxins are present unless sampling and testing is done.
How can I protect myself when camping or recreating at a lake with a bloom?
Stay out of water in or around a bloom and keep children and pets away. Never drink or cook with affected water, and do not allow your pet to drink water from the area. Do not do recreationational activities, such as water skiiing, that cause water to splash into your face or cause water to be aerosolized. Although toxins are not absorbed through the skin, if you or your pet come in contact with a bloom, wash your skin or your pet thoroughly with another source of water and soap if
available.
What precautions should I take when using power boats where a recreational use advisory is in place?
Although inhalation from boat spray is an exposure route, it is a low-risk exposure compared to ingestion (swallowing or drinking). That said, high-speed water activities such as water skiing, wake-boarding or power-boating should be avoided in areas where recreational advisories are in place, as these activities can increase incidental ingestion through falling and can aerosolize the water, making it easier to be inhaled.
What about exposure at recreational facilities, like campgrounds and resident camps?
If drinking water comes from a public water system, campgrounds and residential camps will be notified of any do not drink orders when an issue develops and should follow the precautions advised. Check the system’s website for information. Many campsites are on domestic wells which are not usually impacted when a bloom is present. Direct any questions to the campground host or the agency responsible for the campground. If drinking water is pulled from the water body through a private intake and treated on-site, there could be issues. Check with the host or the responsible agency. An alternative source of water may need to be used unless the system has been tested to ensure reduction or removal of the specific cyanotoxin present. Boiling and camp-style filters are not effective at removing cyanotoxins. In fact, boiling will split cells open, releasing any toxins present. Tap water may be safely used for cleaning surfaces in facilities. Follow any public health advisory for recreational waters if issued by the Oregon Health Authority. Information on recreational water advisories can be found online on our
recreational advisories page.
Can I eat fish or shellfish I catch in a water body under a recreational use advisory due to cyanotoxins?
Fish caught in affected waters pose unknown health risks. If you choose to eat them, remove all fat, skin and organs before cooking because toxins are more likely to collect in these tissues. Crayfish (crawdad) muscle can be eaten but discard all organs and liquids before preparing. It is illegal to harvest clams or mussels from freshwater lakes and you can be fined by the Oregon State Police if caught.
Can I treat toxins in the water to make it safe to drink?
Personal water filtration devices for camping or hiking have not been proven to be effective. Boiling water does not remove toxins and in fact, can increase toxins through evaporation. Most home filtration and treatment devices used to purify water drawn through private intakes are not capable of reducing or removing cyanotoxins. However, for microcystin the global public health organization - NSF International has developed a microcystin test method for drinking water treatment units (NSF protocol 477). The method can verify a water filter's ability to reduce microcystin to below the health advisory levels for drinking water set by the EPA. If you do not own one of the certified systems, or there are other cyanotoxins present, the only way to know if an in-home treatment system is effective at removing or reducing these toxins is to have your drinking water tested when a bloom is identified near your intake.
What causes cyanobacteria blooms?
It's difficult to know the specific cause of any one individual bloom. However, in general, sunlight, warm water temperatures, and high nutrient (nitrogen and phosphorus) concentrations favor the development of these blooms. Nutrients can be naturally occurring (from wildlife and decaying vegetation) or arise from human inputs (fertilizer runoff, manure, failing septic systems, or forest management activities). While cyanobacteria blooms have been occurring since early in earth’s history, climate change is likely to increase factors that promote cyanobacteria growth, increasing the frequency and duration of these blooms.
How big can blooms get, and where are they most prevalent?
Cyanobacteria blooms change rapidly over the course of days and weeks. It is therefore difficult to characterize the size of the bloom in terms of acreage covered or volume of water affected. Not all areas of a lake or other water body may be equally affected. Blooms are often most concentrated around the water’s edge, and in coves, backwater areas, and arms of lakes and reservoirs.
Can any chemicals be used to get rid of a bloom?
Unfortunately, many mitigation methods that can be effective against cyanobacteria growth would harm the river or lake’s beneficial aquatic plant and animal life. These blooms naturally dissipate when conditions no longer favor their growth, such as cooler water temperatures, higher water flow, low sunlight and lower nutrient (nitrogen and phosphorus) concentrations. People can help to reduce the development of blooms by using good management practices around water bodies.
Why do blooms seem to appear overnight?
Most cyanobacteria have evolved to be able to
control their buoyancy. By being able to sink and rise they can move to where
nutrient and light levels are best. During the day, cells get more dense and
less buoyant as they generate food reserves through photosynthesis, which often
results in them sinking into the water column in the late afternoon, where they
can scavenge for nutrients in the deeper water. At night as cells consume their
food reserves, they become less dense and more buoyant, allowing them to float
to the water surface. This is why we often seen scums and dense blooms early in
that day. Cells can also be transported by wind and waves, and may accumulate
in specific parts of a lake as a result.
Who does the sampling, testing and reporting of results for recreational water bodies?
Department of Environmental Quality (DEQ) samples for cyanotoxins in selected Oregon waterbodies between May and September. The DEQ Laboratory analyzes the samples for cyanotoxins and reports the results to the AWQMS database.
Waterbody managers can also contract with laboratories to do their own cyanotoxin testing. OHA’s recreational sampling and advisory guidance documents provide information on best practices for waterbody managers.
How often is sampling performed to determine whether an advisory is lifted or stays in place?
After an advisory is issused, OHA works with partners to schedule follow-up sampling. The exact timing of the follow-up sampling depending on factors such as the duration of the bloom, remoteness of the location, and resources.
For waterbody managers that do their own sampling, this is usually decided by water body managers for individual water bodies. OHA guidance recommends that sampling and analysis for cyanotoxins be conducted every other week after a bloom has been identified. However, OHA’s role is not regulatory, which means we cannot require water body managers to sample and analyze waters used for recreation. That said, if an advisory is issued based on data submitted to OHA, the water body manager must provide data to lift the advisory once the bloom is gone.
How many waterbodies does OHA monitor?
OHA works in conjuction with Department of Environmental Quality (DEQ) to monitor 40 sites in Oregon. The sampling sites were chosen based on factors including the waterbody's susceptbility to cyanoHABs and the location's recreational use level.
Samping at waterbodies that are not included in DEQ's regular monitoring effort is done at the discretion of the designated management agency. Such agencies include, but are not limited to, U.S. Army Corps of Engineers, U.S. Forest Service, Oregon Parks and Recreation Department, cities and counties. In general, these agencies have little to no dedicated financial and staff resources to carry out sampling and analysis throughout the season. Since OHA has no regulatory authority over monitoring, we can’t require agencies to monitor or sample for cyanobacteria or cyanotoxins, even when it is highly recommended.
Does OHA post recreational water quality results?
The public can access recreational data that triggers a recreational use advisory on the cyanobacteria (harmful algae) bloom website here: http://healthoregon.org/hab.
Why are trigger levels for recreation and drinking water advisories different?
A recreational use advisory is issued when cyanotoxins have been confirmed through testing and are at unsafe levels, or a bloom has been sighted and water will be sampled within 1 business day. Toxins for recreational use advisories are measured in a waterbody—a reservoir, lake, or river. Drinking water advisories are based on concentrations of cyanotoxins measured in the finished water, after treatment. Cyanotoxin concentrations are typically much higher in the waterbody than in finished water. Further, the amount of water people incidentally swallow while swimming, water skiing, etc. is much lower than when people use it as a primary drinking water source.
Are these blooms a new problem?
No. cyanobacteria are one of the earliest forms of life on earth and the toxic effects on livestock have been documented for more than 100 years. Bloom formation is linked to environmental conditions and nutrients which provide the elements necessary for cyanobacteria to multiply into what we call a bloom. Blooms are not going away any time soon as global climate change may be increasing their frequency and duration through increased air temperatures and decreasing water levels, creating warmer water temperatures.
Is OHA investigating specific sources that cause cyanobacteria blooms?
OHA’s role is to advise the public on how to reduce exposures once a bloom has been identified. Natural resource agencies are better suited to investigate the causes of blooms, and to work on actions that may reduce the frequency of conditions that favor the growth of blooms.
Recreational Advisory Levels
Health advisory values are different for recreational and drinking water.
The difference between the two reflects the amount of water children and adults incidentally ingest while swimming, water skiing, etc., and the amount of water ingested when drinking from the tap.
Since much more water is ingested through drinking water, the health advisory values for drinking water are much lower than for recreational use advisories.
Recreational Use Values (RUVs) for Cyanotoxins in Recreational Water (in μg/L)
- Microcystin: 8
- Cylindrospermopsin: 15
- Anatoxin-a: 15
- Saxitoxin: 8
Recreational Water
The recreational use advisory values are based on incidental ingestion of water while people are recreating in waterbodies affected by a cyanobacteria bloom and the cyanotoxins that may be produced.
Since people are not intentionally drinking water while swimming, water skiing, wake-boarding or during other recreational activities, the amount of water incidentally ingested over time is much smaller than the amount ingested by children and adults when drinking tap water.
For this reason, OHA uses the recreational values when determining exposures for children and adults while showering, washing hands, cleaning countertops, washing/rinsing teething rings, and all other activities that
could result in incidental ingestion.