Toxic algae was discovered recently in the ponds at South Portland's Hinckley Park. Credit: Courtesy of South Portland Parks and Recreation Department

For the second year in a row, the discovery of a toxic algae bloom likely fortified by dog feces has forced South Portland to close two ponds in Hinckley Park until this fall.

Like last year, bluish green blobs of oscillatoria were discovered in the park, with the Maine Department of Environmental Protection confirming the presence of the toxins on Monday, according to a posting on the South Portland Parks and Recreation Facebook page.

The closure coincides with the reopening on Tuesday of Portland’s East End Beach, which closed this weekend after a wastewater spill of undetermined size into Casco Bay from the East End water treatment plant. The Portland Water District operates and maintains four wastewater treatment plants, including the East End facility, and provides wastewater services to Cape Elizabeth, Cumberland, Gorham, Portland, Westbrook and Windham, according to its website.

According to the Maine Department of Environmental Protection, blue-green oscillatoria algae is found in all lakes and is a natural part of a lake’s ecosystem, but high nutrient concentrations ― from sources such as dog feces and lawn fertilizer runoff ― can promote a population explosion of these organisms and result in algal blooms, especially during warm weather.

The algae can damage the liver or nervous system, produce gastrointestinal symptoms or cause skin irritation, according to the Maine Department of Environmental Protection.

The ponds will remain closed until the fall weather helps kill off the algae by cooling the water.