Cyanobacteria and Harmful Algal Blooms
If you suspect that Lake Winnipesaukee is experiencing a cyanobacteria bloom please notify LWA and NH DES immediately.
The map linked below indicates Cyanobacteria observations and advisories in the Lake Winnipesaukee watershed. The report card summarizes key information that can have an influence on cyanobacteria. The report card is updated on a weekly basis and the map is updated as needed.
Surface blooms can rapidly change and accumulate in various locations around a waterbody. NHDES advises lake users to avoid contact with the water in areas experiencing elevated cyanobacteria cell conditions, also known as a bloom. NHDES also advises pet owners to keep their pets out of any waters that have a cyanobacteria bloom.
To Report a Bloom: Take a picture of the suspected bloom and send it to NHDES and LWA with the date/time/location and your contact information
- Report a Bloom to NHDES
- Text/Call HAB Hotline: (603) 848-8094
- Email: HAB@des.nh.gov
- Contact LWA
- Text/Call: (603) 581-6632
- Email: brossiter@winnipesaukee.org
Plan Ahead Before Venturing Out!
- NHDES Healthy Swimming Mapper
- NHDES Waterbody-Specific Cyano Updates
- Sign Up for Weekly NHDES Updates
Sighting Locations: Please note that the map is meant to be used as an informational tool with approximate locations of cyanobacteria sightings. Click the points on the map for additional details. Surface blooms can rapidly change and accumulate in various locations around a waterbody. The green circles represent confirmed sightings while red circles represent active advisories issued. The purple circles represent advisories that have been removed. State advisories are issued when samples are collected and identified with cell concentrations exceeding the state threshold of 70,000 cells/ml. Click each point on the map below for additional information about each observation/advisory.
Click Here to View a List of Observations and Advisories (2019-2021)
Click Here to View a List of Observations and Advisories (2022)
Is that cyanobacteria? LWA has created this guidance document to assist people with identifying potential bloom formations in our lakes. Please note that not all cyanobacteria blooms look alike and are often mixed in with pollen or other algae. This document is to be used for general guidance only. If you suspect a bloom, please stay out of the water. NHDES advises lake user and their pets to avoid contact with the water in areas experiencing elevated cyanobacteria cell conditions.
Additional Information