Harmful Algal Blooms

blue green algae

Cyanobacteria / Harmful Algal Blooms (HABs)


Excerpts of information from Idaho Department of Environmental Quality &

Idaho Dept of Health and Welfare



2019 Impacts & Advisories for Ada, Elmore, Boise and Valley Counties

9/6/2019 - Health advisory issued for Lake Cascade in Valley County - Lifted on 11/4/2019

8/16/2019 - Health advisory issued for Little Camas Reservoir in Elmore County

7/31/2019 - Health advisory issued for Mountain Home, Indian Creek and Blacks Creek Reservoirs
  • For a map of statewide harmful algal blooms and related health advisories, click HERE. (link to the DEQ's website)

Most of the year, Idaho's beautiful lakes, reservoirs and ponds are safe to enjoy. However, when water temperatures rise and the right type of nutrients are available, some bodies of water can produce Cyanobacteria which can produce harmful algal blooms (HABs). These blooms can pose health risks to humans, pets, livestock, and wildlife. 

In Idaho, only a fraction of all water bodies are monitored due to limited physical and monetary resources. The absence of an advisory is not an indication that a HAB or E. coli is not present at a water body. You are your own best advocate when ensuring your safety, and that of your family and pets. Be aware and "when in doubt, stay out."

What is a Harmful Algal Bloom?

Cyanobacteria occur naturally in the environment and are a vital part of the ecosystem. A harmful algal bloom occurs when excessive growth cyanobacteria exists, which has the potential to produce toxins. Abundant nutrients (phosphorus and nitrogen), sunny conditions, warm temperatures, and low-flow or low-water conditions can contribute to exponential growth resulting in algal blooms.

Appearance

Blooms can vary in appearance, sometimes looking like mats, foam, or surface scum — especially near the shoreline. Blooms can range in color from blue and bright green to brown and red. Some blooms produce a foul odor.

Blooms can occur at any time, but they most often occur in late summer or early fall. Often in association with a HAB, you may hear reference to cyanobacteria.


IMPACTS TO HEALTH

Not all blooms are toxic, but when toxic harmful algal blooms do occur they present a health risk to humans, pets, and livestock. Exposure may occur from ingestion, skin contact, or inhalation. Exposure can result in a range of health effects from skin irritation and stomach upset or pain to neurotoxic effects and at very high levels, death.

The most common health effects are skin and eye irritation. Other more severe health effects can include:

Difficulty breathing
Stomach pain
Nausea
Vomiting
Diarrhea
Dizziness
Numbness and tingling in lips, fingers, and toes

Symptoms in humans and pets can occur within minutes of exposure but may take as long as 36 hours to develop depending on the particular toxin and its concentration (CDC 2016). Anyone with symptoms should seek medical attention.

Call your pet's veterinarian immeditely if your pet has been around an algal bloom and shows symptoms such as vomiting, staggering, drooling or convulsions.


HEALTH ADVISORIES

When a harmful algal bloom is suspected, the Idaho Department of Environmental Quality (DEQ) will collect a water sample from the affected water body and send it to a lab for analysis. Health advisories are issued for a water body when the number of cells in the water is above a level recommended as unsafe for recreating.

When a health advisory is issued, is the entire water body unsafe for recreational use?

Algae blooms are known to be very patchy in nature. Higher densities may be present in areas not surveyed, particularly along shorelines. The density of a harmful algal bloom can change with wind direction and temperature. Regardless of whether a health advisory is in effect, recreational users should avoid contact with water whenever surface concentrations of cyanobacteria are evident or when the lake has scums with obvious green to blue-green appearance.


PROTECT YOURSELF AND PETS

People and animals can be exposed to HABs by swallowing water and/or touching the water during recreational activities such as swimming, water skiing, and diving.

The following precautions are recommended when an advisory is in effect. However, whether or not a health advisory is in place, if the water looks questionable, the best advice is, when in doubt, stay out.

Avoid exposure to water experiencing a harmful algal bloom. Take extra precautions to ensure children, pets, and livestock are not exposed to the water.

Do not consume water with a harmful algal bloom. Neither boiling nor disinfecting removes the toxins from water.

If fish are known to have been exposed to a harmful algal bloom, only consume the fillet portion (remove the fat, organs, and skin). Wash hands after handling. The risk associated with consuming fish caught in waters with a harmful algal bloom is unknown. Toxins produced by a harmful algal bloom can accumulate in the organs of fish.

Symptoms can occur within an hour of exposure but may take as long as 36 hours to develop depending on the particular toxin and its concentration (CDC 2016). Anyone with symptoms should seek medical attention. If you experience mild irritation, rinse with clean water immediately.

If your pet comes in contact with a bloom, rinse them with clean, fresh water immediately. If severe symptoms occur, call a veterinarian immediately. In severe cases, animals may die within tens of minutes to hours after they have been exposed to harmful algal blooms. When harmful algal blooms decompose, they can also kill fish that live in the water.  


How to Report Potential HABs

In Idaho, only a fraction of all water bodies are monitored due to limited physical and monetary resources. The absence of an advisory is not an indication that a HAB or E. coli is not present at a water body. You are your own best advocate when ensuring your safety, and that of your family and pets. Be aware and "when in doubt, stay out."

You can help report potentially harmful algal blooms in Idaho:

Idaho DEQ - Bloomwatch Reporting Site

Resources

Frequently Asked Questions on HABs
Idaho DEQ: Harmful Algal Blooms

Idaho Health & Welfare: FAQs About Harmful Algal Blooms
Protect Your Pets

Past Health Advisories

2018 Lifted Advisories

upcoming events

Events Timeline



NOV 11
VETERANS DAY-OFFICES CLOSED

All Offices

NOV 1411a-1p
R4 BEHAVIORAL HEALTH BOARD MEETING

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CDH - Boise Office
707 N. Armstrong Pl., Boise

NOV 18 3:30p-4:30p
WIC BREASTFEEDING SUPPORT GROUP

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CDH - Boise Office
707 N. Armstrong Pl., Boise

contacts


Ada County

Elmore County

Boise County

Valley County

208-327-7499

208-587-4407

208-327-7499

208-634-7194