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New Hampshire Department of Environmental Services

Cyanobacteria and Drinking Water
Information for Public Water Systems

Cyanobacteria are microscopic organisms found naturally in lakes, streams and ponds. Once known as blue-green algae, they are actually photosynthetic bacteria. When present at low density they do not cause recreational or aesthetic problems. However when conditions are optimal for their growth, these organisms can sometimes multiply to form harmful algal blooms (cyanoHABs) that can potentially produce toxins capable of affecting liver and kidney functions or the central nervous system, or causing skin irritations.

In addition to producing toxins, cyanobacteria can pose other treatment challenges for public water suppliers, including taste and odor issues and shortened filter run times. While not regulated as drinking water contaminants, some cyanobacteria toxins have been included among the parameters that certain public water systems using surface water will be required to monitor under the Unregulated Contaminants Monitoring Rule beginning in 2018. In 2015, USEPA issued health advisory levels for two cyanobacterial toxins Adobe Acrobat Reader Symbol. The information below is provided to guide drinking water suppliers in preventing, identifying and responding to cyanobacteria blooms.

More information is available in the fact sheet, Cyanobacteria and Drinking Water: Guidance for Public Water Systems.

If you see a cyanobacteria bloom, call 603-848-8094Are you experiencing a bloom?

Contact NHDES:

Jody Connor Limnology Center (JCLC): Call in the following order

  • (603) 848-8094 (Beach Coordinator mobile – primary contact number for Cyanobacteria issues)
  • (603) 271-0698 (Beach Coordinator office)
  • (603) 271-8865 (JCLC Director office)

Drinking Water and Groundwater Bureau

  • (603) 271-2513 (8:00 AM – 4:00 PM weekdays except holidays)
  • (603) 223-4381 (outside business hours)

NHDES Bloom Response Strategy

NHDES CyanoHAB Response Protocol for Public Water Supplies Adobe Acrobat Reader Symbol

NHDES Funding Sources

Cyanotoxin Monitoring Equipment and Training Grants

Local Source Water Protection Grants

Prevention and Treatment

US EPA Ground Water and Drinking Water – Cyanotoxins in Drinking Water

American Water Works Association – Cyanotoxins Resource Community Website

Water Research Foundation – Cyanotoxin Guides for Water Utility Managers

Other Resources:

For information about recreational exposure to cyanobacteria, visit the Beach Inspection Programs webpage.

For current posted cyanobacteria beach advisories or lake warnings, check the Current Beach Advisories webpage.

Cyanobacteria Monitoring Collaborative

Toxic Cyanobacteria of New England – “The Dirty Dozen”

Contact Us

  • Paul Susca
    NHDES Drinking Water & Groundwater Bureau
    29 Hazen Drive; PO Box 95
    Concord, NH 03302-0095
    (603) 271-7061
    (603) 271-0656 (fax)
  • Liz Pelonzi
    NHDES Drinking Water & Groundwater Bureau
    29 Hazen Drive; PO Box 95
    Concord, NH 03302-0095
    (603) 271-3906
    (603) 271-0656 (fax)



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NH Department of Environmental Services | 29 Hazen Drive | PO Box 95 | Concord, NH 03302-0095
(603) 271-3503 | TDD Access: Relay NH 1-800-735-2964 | Hours: M-F, 8am-4pm

copyright 2017. State of New Hampshire