Healthy Swimming Mapper

Map Navigation Tips:

• Current beach advisories, cyanobacteria warnings or cyanobacteria watches are listed on the right-hand side dashboard.
• Click on the right-hand side dashboard or the place of interest on the map to display a pop-up window. The pop-up window will show the current status, previous sampling results, photos and historical reports for a specific beach or waterbody.
• Use the search bar on the top right corner of the map to find your local beach or waterbody by name or municipality.
• On a mobile device, click on the arrow buttons on the bottom of the screen to see cyanobacteria warnings or cyanobacteria watches. 

Beach Inspection Program

The Beach Inspection Program monitors public beaches for the presence of fecal bacteria from Memorial Day through Labor Day. A beach advisory is issued when a water sample contains fecal bacteria levels that exceed the state standard, indicating unhealthy swimming conditions. Enterococci is used as the indicator fecal bacteria at coastal beaches while E. coli is used at freshwater beaches.

A coastal beach advisory is issued if 1 sample exceeds 104 MPN/100 mL.

A freshwater beach advisory is issued if 1 sample exceeds 158 MPN/100 mL or 2 samples exceed 88 MPN/100 mL.

Once an advisory is issued, resampling will occur the following day and will continue until the fecal bacteria levels do not exceed the state standard.

Cyanobacteria Harmful Algal Bloom Program

The Cyanobacteria Harmful Algal Bloom Program monitors waterbodies when a potential cyanobacteria bloom is reported by a member of the public. A cyanobacteria warning (advisory) is issued lake-wide when cyanobacteria cell concentrations exceed 70,000 cells/mL (Administrative Rule Env-Wq 1108.14). Warnings are not based on toxin evaluation but occur at cyanobacteria cell count densities when toxin production may be likely. These are intended as a precautionary measure for short-term exposure to cyanotoxins. When a warning is issued, resampling is performed weekly until the bloom subsides. Warnings are issued from May 15 through October 15.

A watch may also be issued for a waterbody to serve as a statement to be on the watch for a potential cyanobacteria bloom. Sometimes watches become warnings, and sometimes the bloom will pass before an warning is issued. Watches remain active for a week. Resampling only occurs if further bloom reports are submitted. Watches are issued year-round as needed. A watch may be issued based upon a photo before NHDES can analyze a sample; if the cyanobacteria density is approaching 70,000 cell/mL but has not exceeded; or if the bloom has been reported to have passed by the time sample analysis is performed but may reoccur.