MANSFIELD - The advisory against swimming or swallowing water at Fulton Pond due to a harmful algae bloom has been lifted.

The state Department of Public Health test results have shown that the cyanobacteria in Fulton Pond has decreased to below a level of concern, the Mansfield Board of Health announced Sept. 26.

A warning was issued in late August after the DPH visually confirmed a cyanobacteria algae bloom in Fulton Pond on Aug. 28.

The Mansfield Health Department advised people not to swim or swallow water at Fulton Pond and to keep animals away and and rinse them off if they did come in contact with the water.

Algae blooms form in fresh water when cyanobacteria (blue-green algae) grow quickly and form scum or mats in the water. Some blooms can produce toxins harmful to people and animals, according to the DPH.

Health concerns from harmful algae blooms and their toxins vary depending on the type of exposure and the amounts and types of toxin present.

Contact with these algae can cause skin and eye irritation.

Ingesting small amounts can cause gastrointestinal symptoms. Ingesting large amounts of toxins may cause liver or neurological damage.

Inhaling water spray with algae in it can cause asthma-like symptoms.

Small children and pets are more susceptible to the effects of toxins than adults. Livestock and pets have died from ingesting algal toxins.

Possible causes of algae blooms, according to the state DPH website, are:

Certain environmental conditions, such as warm weather, sunlight, and excess nutrients in the water, help blue-green algae grow faster.

Excess levels of nutrients in water bodies can come from human-related sources.

Phosphorus and nitrogen are two important nutrients used by blue-green algae in their growth. They are found in fertilizers and human and animal waste.

Examples of sources that can input large amounts of nutrients to water bodies are leaking septic or sewer systems, storm water runoff, lawn fertilizers, pet and wildlife waste, and agricultural activities.

Residents can contact the Mansfield Health Department at 508-261-7366 or Health@Mansfieldma.com with any additional questions or go to www.mass.gov/info-details/harmful-algae-blooms-in-fresh-water-bodies.