Idaho DEQ harmful cyanobacteria bloom information
Maps and data for monitoring cyanobacteria blooms in Idaho
Use the navigation links above to quickly navigate to the section you are looking for, including the Health Advisory Map and Potential Bloom Map
Please report suspected blooms:
- Use the Report A Bloom form. Please place a location on the map and add photos of the water. Photos are really useful for pre-screening potential blooms.
- Email algae@deq.idaho.gov with a description of the potential bloom. Please include the water body's name, the location of the bloom, and attach photographs,
- Call the DEQ regional office for the region the lake is in.
Cyanobacteria
Many of us learned about “blue-green algae” in school, but these algae are actually bacteria that photosynthesize, turning sunlight into energy, like plants. These algae, properly called cyanobacteria, occur naturally in Idaho’s lakes and rivers. During the summer months cyanobacteria populations can grow, or bloom, to densities that outcompete the other phytoplankton in the lake.
Cyanobacteria make a variety of chemicals, known as cyanotoxins that can be harmful to many other organisms, including people, animals, and fish. Cyanotoxins can remain in the water days or weeks after a bloom is no longer visible.
Cyanotoxins
You can be exposed to cyanotoxins through skin contact and by eating or drinking (ingesting) the water. Exposure to cyanotoxins can cause health effects ranging from mild skin irritation and upset stomach to more serious effects including trouble breathing or even death. Anyone with symptoms should seek medical attention. Cyanotoxins can also be particularly harmful to dogs and other animals that may swim in the water.
Is it safe to fish in waters with a bloom?
It is best to avoid direct contact with water affected by a bloom. If you choose to fish in affected water, wear protective clothing such as gloves or waders, and wash your hands thoroughly with clean water.
There have been no reports of people becoming sick from eating fish caught during a bloom. Information about the risk of eating fish from affected waters is limited. However, fish fillets are less likely to accumulate toxins compared to other parts of the fish. If you decide to eat fish from affected waters:
- Remove the skin, organs, and fatty deposits from the fish
- Avoid cutting into organs
- Rinse the fillets with clean water before cooking
More health information can be found on the Idaho Department of Health and Welfare Harmful Algal Bloom page.
DEQ bloom response and monitoring
DEQ and the Idaho public health districts rely on boaters, fishermen, and anyone who visits Idaho's lakes to let us know when they see a potential bloom, there are simply too many lakes and reservoirs for us to actively monitor. Please email photos, descriptions, and location information to algae@deq.idaho.gov.
Once a report has been received:
- DEQ staff will visit the water body, typically within 1-2 days,
- They will make a visual observation (is a potential bloom visible and how large an area does it cover),
- Collect two samples - one to see if any toxin producing species are present and identify which ones, the second sample will be used to determine if toxins are present in harmful concentrations.
Recreation Health Advisories
This section is updated as this year's health advisories are issued and lifted. The Recreation Water Health Advisories map on the DEQ website is maintained and updated as health advisories are issued and lifted.
DEQ and the Idaho public health districts work together to issue a health advisory. A health advisory informs the public of where an active, potentially toxic bloom has been confirmed. DEQ staff typically respond to reported blooms by visiting the water body, collecting samples, identifying the potential toxin-producing species, and analyzing the sample for toxins. The public health districts use the sample data and DEQ observations to issue a health advisory. Health advisories are lifted once two samples, collected a week apart, have toxin levels below the safe threshold.
Health Advisories Map
The health advisories map has moved to the Department of Health and Welfare. This space will be updated when a link is available.
DEQ Cyanobacteria Response and Monitoring
DEQ staff use several techniques to monitor harmful cyanobacteria in Idaho water bodies. These techniques allow DEQ to identify potential blooms before they begin and estimate a bloom’s cyanobacteria population density. Satellite (remote sensing) technologies allows DEQ staff to remotely monitor water bodies for the following purposes:
- to identify water bodies that may be in the early stages of bloom development,
- to monitor a bloom’s density once high toxin levels are confirmed,
- to determine when toxin concentrations may have returned to safe levels.
Potential Bloom Map
This map displays the estimated abundance or number of cyanobacteria cells in large water bodies, based on calculations from the satellites. It is designed as a screening level analysis tool. Decisions for health advisory postings will be made based on results from water quality samples. No regulatory decisions, or signage postings, should occur based solely on information from the map.
Satellite data allows DEQ staff to remotely monitor Idaho's lakes and reservoirs and see an estimate of how many cyanobacteria are in the water. The data comes from NASA and European Space Agency satellites and updates are usually received every 3 -4 days.
- Cascade Reservoir Sample Collection Data:
- Sample date: 6/22/2022
- Water body: Cascade Reservoir
- Location: Blue Heron, Sugar Loaf, Boulder Creek Arm
- DEQ Contact: (208) 373-0550
- Health District Contact: (208) 375-5211
- Toxin results: Blue Heron: Microcystins: 0.31 ng/mL.
- The microcystin contact recreation threshold is 4 ng/mL.
- qPCR results: Toxin genes detected: 0
- Notes: Low levels of toxins were detected in the sample. Further investigations may attempt to identify where these toxins are coming from.
Cyanobacteria Assessment Network (CyAN)
Remote sensing data allows DEQ staff to remotely monitor their region's lakes and reservoirs as the summer bloom-season begins to identify which water bodies may be in the early stages of bloom development, remotely monitor the density of a bloom once high toxin levels are confirmed, and see when population levels are returning to the normal levels that indicate toxin concentrations may have returned to safe levels.
CyAN - Cyanobacteria Assessment Network: a NASA, EPA, NOAA, and USGS Project
The CyAN project agencies collaborated to develop an early warning indicator system for detecting algal blooms in U.S. freshwater systems. This research supports federal, state, tribal, and local partners in their monitoring efforts to assess water quality to protect aquatic and human health.
Pictures of Idaho Blooms
Pictures of harmful blooms from across Idaho
Examples of plants and algae that are not cyanobacteria
Additional resources
Frequently Asked Questions
How can I tell if the water has cyanobacteria? If you suspect the water is not safe to be in the best course of action is to notify DEQ. The Jar and Stick Test can be used to differentiate between the kinds of cyanobacteria that float and other types of phytoplankton that do not typically float.
What about other types of algae? Algae in our lakes, ponds, and streams are an essential component of the food web and a healthy aquatic ecosystem. Algae have many forms and colors, and most do not produce toxins. Cyanobacteria are the exception, when some bloom toxins can be produced.
Can I swim and undertake other water sports when a bloom is in process? Swimming and water sports, including water skiing,or other activities that result in direct contact with affected water are not recommended.