FREQUENTLY USED TERMS 

Cyano Status LOW

Monitoring results indicate no or low concentrations of cyanobacteria detected. To the best of our knowledge at the time and location of sample collection, regular recreational usage of the pond is safe with respect to cyanobacteria and toxins.

Cyano Status MODERATE

Monitoring results indicate moderately high levels of cyanobacteria concentrations detected. While these conditions pose low to minimal health risks to adults, they can be dangerous for children or pets if water is ingested accidentally or incidentally during recreational activities. Pet exposure can be from drinking pond water or grooming after swimming. Due to lower body masses, children and pets are more susceptible to impacts at lower concentrations than adults. 

Cyano Status HIGH

Monitoring results indicate high levels of cyanobacteria concentrations detected. Health risk to adults is high and is especially dangerous for children and pets when ingested. Town water monitoring has found cyanobacteria concentrations near or exceeding state recreational standards with potential for exponential growth rates of cyanobacteria. Any accidental consumption of pond water is considered dangerous and interacting with the pond in general carries risk for adverse health effects. When Cyano Status is High, the Concord Health Division will take the following actions:

• Water Use Advisory signage will be posted at all public access points to White Pond; signage will advise the public against swimming and other contact with the pond water.

• A notification of the Water Use Advisory will be issued via the town’s News and Notices email listserv and posted on the town’s social media accounts.

Two Common Types of Cyanobacteria Frequently Seen in White Pond

• Microcystis – A genus of cyanobacteria that is common in Cape Cod ponds. It can produce hepatotoxins, dermatoxins, and neurotoxins, but is known to produce Microcystin toxin at relatively high levels.  Most Water Use Advisories posted for White Pond have been based on the presence of microcystin toxin.
• Dolichospermum – A genus of cyanobacteria very common in Cape Cod ponds. It can produce hepatotoxins, dermatoxins, and neurotoxins, but is known to produce Microcystin at relatively low levels.  

Common Toxins Produced by Cyanobacteria

• Dermatoxin – A toxin that is a skin irritant. The most commonly occurring dermatoxin, lipopolysaccharide, is unregulated by the state.
• Hepatotoxin – A toxin that can cause liver damage.
• Microcystin – A type of hepatotoxin that can cause liver damage and is the primary cyanotoxin regulated by the Massachusetts Department of Public Health.
• Neurotoxin – A toxin that can cause neurological damage. Anatoxin and beta-N-methyl amino-L-alanine (BMAA) are known neurotoxins that are unregulated by the state, but are currently being studied by cyanobacteria researchers.

Dominance

Indicates which type of cyanobacteria is most abundant in a given sample. A “mixed” dominance sample indicates roughly equal abundance of different types. This information is important because different types of cyanobacteria produce different types of cyanotoxins at different rates.

Possible Pet Health Effects

Pet exposure can be from drinking pond water or grooming after swimming. Due to lower body masses, pets are more susceptible to impacts at lower concentrations than adult humans. Pets exposed to suspected cyanotoxins should be rapidly assessed by a veterinarian.

Scum

A visible material is present as a dispersed or dense floating layer on the pond surface, or as scum washed up on the shoreline at the water’s edge. Scums may be blue, green or yellow, anns can sometimes look like swirls of paint in the water.    A visible cyanobacteria scum can indicate high toxin levels in the pond.  The Massachusetts Department of Public Health generally requires that Water Use Advisories prohibiting swimming be posted when persistent cyanobacteria scums are present.   and the state recommends avoiding contact with the pond for a minimum of two weeks after a cyanobacteria scum has formed.[sr1] 

Massachusetts Department of Public Health (MDPH) Criteria for Water Use Advisories

The Concord Health Division will post public health Water Use Advisories prohibiting swimming and avoiding recreational contact with pond water when weekly water sampling results show a condition of Cyano Status High, or when pond water exceeds the following MDPH criteria:

• If a visible cyanobacteria scum or mat is evident
• If either the cycanobacteria cell count exceeds 70,000 cells/mL or the toxin level of lysed cells meets or exceeds 14 ppb (check to see if this has been changed to 8 ppb)  microcystin.
• Since decreasing cell counts indicate cell die-off and dying cells may release toxins, algal toxin concentrations in the water may rise for a period of time after cell counts decrease.  Water Use Advisories may be lifted after two successive and representative sampling rounds one week apart demonstrate cell counts or toxin levels below those at which an advisory would be posted