HABs (Harmful Algal Blooms)

What is an Algal Bloom?

Is an abundant or excessive growth of algae.

What is a Harmful Algal Bloom?

A harmful algal bloom (HAB) is a large growth of planktonic bacteria.  HABs are actually cyanobacteria, which are commonly referred to as "blue-green algae" and may produce toxins.  These toxins may affect the liver, nervous system and/or skin.

What causes blooms to form?

Like plants and true algae, cyanobacteria have a pigment called chlorophyll that captures sunlight to photosynthesize sugars for energy.  Aquatic plants and algae require nutrients, especially phophorus and nitrogen, from the water or sediment to grow.  Not all algal blooms are HABs.  Some true algae like Cladophora can also create large blooms with the right nutrient and light conditions.  Such blooms can be a serious nuisance and cause environmental problems but do not generate the toxins associated with many cyanobacteria.

Factors that can contribute to HABs
  • excess nutrients (phosphorus and nitrogen)
  • sunlight
  • low-water or low-flow conditions
  • calm water (low wind conditions)
  • warmer temperatures
  • low salinity
  • selective grazing (avoiding cyanobacteria) by zooplankton or zebra/quagga mussels

The presence of cyanobacteria does not necessarily mean that toxins are being produced.  The level of toxicity depends on the strains present and environmental factors.  HAB toxicity also depends on the sensitivity, the age, and the sex of the animal or person that consumes or comes into contact with the toxin.

Useful links

  •  Visit the Ohio EPA's webpage here more general information about algae and HABs.
  • Ohio EPA's Public Water System Harmful Algal Bloom Response Strategy provides guidelines on monitoring and sampling protocols, identifies acceptable analytical methods, identifies cyanotoxin levels that will be used to make drinking water use advisory decisions and recommends contingency planning for public water systems.  Download the Strategy document here.
  • NOAA hosts recent satellite imagery of Lake Erie from the MODIS equipment on board NASA's Aqua and Terra satellites.  Algal blooms are often easily visible on the imagery.  The latest satellite images are available here.
  • NOAA also provides a weekly bulletin providing the latest HAB status in Lake Erie from a number of sources.  The latest bulletin is available here.
  • The City of Toledo has established a water quality dashboard to provide citizens with the latest water quality status water from the City's treatment plant.  Toledo's dashboard is available here.
  • The City of Toledo maintains a buoy to monitor conditions near the water intake for the Collins Park Water Treatment Plant.  Visit the buoy's reporting site here.
  • Northwestern Water & Sewer District employs the CodeRED emergency notification system to provide customers with important information. Sign up for CodeRED voice notifications here.

In August 2014, there was an algal bloom in western Lake Erie that resulted in the City of Toledo issuing a notice to Toledo water customers not to use their water. The water ban lasted for just over 2 days.

The following images show the HAB in western Lake Erie in August 2014. Click on one of the images to see a larger version.

                           Credit for Images: NASA Earth Observatory, August 2014; http://earthobservatory.nasa.gov/


Algal Bloom News

Toledo, August 2014

2017 HAB

The District provides treated water from five different water sources including Lake Erie, the Maumee River and smaller streams.  This year, along with the water treatment facilities, The District is monitoring harmful algal blooms (HABs) in all of our water sources.  

NOAA forecasters are predicting a significant bloom this season.  Toxic algae has NOT been detected in our drinking water, however small amounts of microcystin have been detected in raw water samples collected from the western Lake Erie Basin.

District Customers using Lake Erie as a Water Source:

Approximately, 6,500 customers are supplied with Lake Erie water treated by City of Toledo (Rossford, Perrysburg Township, Walbridge, Lake Township and the western portions of Northwood). 

Approximately 3,000 customers are supplied with Lake Erie water treated by the City of Oregon (Oregon, Millbury, and eastern portions of Northwood). 

Our remaining water customers get their water from rivers and streams.  

The District does not expect a repeat of the 2014 water crises.  

If you are concerned about HABs:

  1. Know where your water comes from. CLICK HERE TO FIND OUT!  
  2. Sign up for emergency notifications.  In Wood County offers CODE Red emergency notification.  Sign up or be sure your information is updated. 
  3. The Federal Emergency Management Agency also recommends you keep a supply of water for all types of disaster.  LIST OF ITEMS FOR EMERGENCY SUPPLY KIT