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Harmful Algal Blooms (HABs) Notifications Page

Introducing NYHABS: a new HAB locations map. HAB locations are updated through October.

HAB Locations in New York State

The link below displays the location of HABs in New York State. Each yellow dot represents a HAB reported in the past 2 weeks. There may be other waterbodies with HABs that have not been reported to DEC.

NYHABS (leaves DEC website) displays the location of current freshwater (non-marine) HABs in New York State. Try switching browsers if the application does not load properly.

Map Icons

  • Current HABs (yellow icons) have been reported through DEC's reporting system within the last two weeks.
  • Archived HABs (grey icons) have been reported through DEC's reporting system within the current season (2019).

NYHABS can also be accessed through an easy to remember short link:

What if the map shows a HAB on my waterbody?

Avoid contact with HABs. HABs in large lakes or rivers may be limited to specific shorelines or confined bays. Portions of any of these waterbodies may be clear and fully support recreational uses.

The public should use the information on this site to help them to make informed decisions about where and when to recreate, particularly outside of designated swimming areas. Swimmers and recreational users should remember that health and safety cannot be assured outside of designated swimming areas- for more swimming information, visit DEC's swimming webpage.

The NYHABs map does not include

What the NYHABS map shows

Each dot on NYHABS represents an individual HAB observation, and includes the date of the observation, the HAB status, the extent of the HAB, who reported the HAB, the county, and any pictures submitted in the report.

HAB Status

DEC HABs Program staff use visual observations, digital photographs and laboratory sampling results to determine whether a reported bloom consists of cyanobacteria (which would indicate a HAB), or another type of algae. If the bloom is thought to be a HAB, it is labeled with one of three statuses, described below. Exposure to blooms can pose health risks to people and pets, regardless of whether toxins are present.* Therefore, people and animals should avoid any visible blooms.

  • Suspicious Bloom: DEC staff determined that conditions fit the description of a cyanobacteria bloom (HAB), based on visual observations and/or digital photographs. Laboratory analysis has not been done to confirm if this is a HAB. It is not known if there are toxins in the water.
  • Confirmed Bloom: Water sampling results have confirmed the presence of a cyanobacteria HAB which may produce toxins or other harmful compounds.
  • Confirmed with High Toxins Bloom: Water sampling results have confirmed that there are toxins present in enough quantities to potentially cause health effects if people and animals come in contact with the water through swimming or drinking.

*Some HABs can produce toxins, some do not. However, exposure to any HABs can cause health effects in people and animals when water with blooms is touched, swallowed, or when airborne droplets are inhaled. Exposure to high levels of HABs and their toxins can cause diarrhea, nausea or vomiting; skin, eye or throat irritation; and allergic reactions or breathing difficulties.


The extent of the bloom is a rough estimate of the size of the bloom within the waterbody and is recorded by monitoring program staff or from public reports.

  • Small Localized: Bloom affects a small area of the waterbody, limited from one to several neighboring properties.
  • Large Localized: Bloom affects many properties within an entire cove, along a large segment of the shoreline, or in a specific region of the waterbody.
  • Widespread or Lakewide: Bloom affects the entire waterbody, a large portion of the lake, or most to all of the shoreline.
  • Open Water: Sample was collected near the center of the lake and may indicate that the bloom is widespread and conditions may be worse along shorelines or within recreational areas. Special precautions should be taken in situations when a Confirmed with High Toxins Bloom is reported with an Open Water extent because toxins are likely to be even higher in shoreline areas.

Reported by

The data provider is also listed for each record on NYHABS. Reports may come from the public, or other monitoring programs such as the DEC Lake Classification and Inventory (LCI) Program, Citizen Statewide Lake Assessment Program volunteers, and partner HABs monitoring programs.

How to filter records on NYHABS

NYHABS records can be filtered by county and waterbody.

To filter records on the map:

  • Click on the funnel in the info tab on NYHABS, labeled "Filter HAB reports".
  • Users may filter either just one type of HAB report (current or archived) or both.
  • Select the lake or county from the dropdown and toggle the filter on. The filter is on if the toggle is green.
  • Only waterbodies or counties with HAB reports will appear in the dropdown choices.
  • To turn off filters, and view the entire data set, either refresh the page, or turn off the filters so the toggles are grey.

How to print records from NYHABS

NYHABS also has a print records feature. The printing feature will only print those records displayed on the map. If any filters are enabled, only those records will be printed.

To print HAB records:

  • Click on the print records widget in the info tab on NYHABS, labeled "Print HAB records".
  • Use one of the two drawing methods to select the records for printing.
  • Draw a box around the desired HAB records.
  • Click the print records button.
  • Select from both or either of the current or archived HABs records.
  • Hit the printer icon to start printing.
  • Select the desired layout, or paper size.
  • Select print again.
  • A new window will open with a .pdf report with a map of the boxed records.
  • Select the print icon on the top of the ribbon to save or print.
  • Directions are also available on the info tab for NYHABS.

Report a HAB through the NYHABS system

Use the Suspicious Algal Bloom Report Form (leaves DEC website).