Rhode Island’s Ten Mile River Clear of Toxic Algae
PROVIDENCE, Rhode Island, December 24, 2007 (ENS) – The Rhode Island Department of Environmental Management and the Department of Health have lifted the four month long “no contact” advisory imposed for the Ten Mile River and its impoundments, Turner Reservoir and Omega Pond.
The river originates in Massachusetts and forms the boundary between Massachusetts and Rhode Island along the northern half of East Providence and Seekonk.
In September, a dense algae bloom turned the waters of Turner Reservoir a bright green color.
Laboratory results from tests on water samples taken at that time found high levels of the naturally occurring algal toxin, microcystin.
Toxic microcystis algae
(Photo courtesy NOAA)
The levels, which exceeded 25,000 micrograms per liter, were significantly above the guideline of 40 micrograms per liter from the World Health Organization.
Since microcystin can still be present in elevated levels for a time even after the end of a bloom, Department of Environmental Management personnel conducted more sampling on November 23.
Those test results showed microcystin at only 0.2 micrograms per liter, well below the health threshold.
Microcystis is an algae that grows naturally on the surface of many waterbodies. Under certain conditions, such as warm weather and an abundance of nutrients in the water, the algae may undergo an explosive type of growth that results in dense, floating mats of algae, commonly referred to as an algae bloom.
As the days get shorter and cooler, the algae dissipated and any toxins remaining in the water declined as the algae died off. In addition, rainfall helped to circulate the water and break up the blooms.
High levels of microcystin in water causes serious damage to the liver when the water is used as a water supply, or when water is swallowed repeatedly during swimming or other recreational activities.
Symptoms of exposure to microcystin include stomach cramps, vomiting, diarrhea, fever, muscle and joint pain, and irritation of the skin, eyes and throat.
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