Boating rentals have resumed at Piney Run Park following an advisory from Carroll County officials, who discovered the reservoir contained toxins produced by a summer algae bloom.
Park patrons could rent equipment starting Aug. 1, though the algae, and the toxins, were still then present.
A field test revealed that as of Aug. 8 both the toxins and most of the algae have dissipated, according to Kate Heilman, the county's water resource specialist in the Department of Land Use, Planning and Development.
The county recommended that Piney Run park staff close boating rentals beginning July 25, because of a distinct visual increase in the amount of algae on the lake. Officials from Heilman's department tested the reservoir, also called a lake, July 25 and determined the water contained microcystin, which is harmful to both humans and pets.
The Maryland Department of Health and Mental Hygiene would conduct a test that would more accurately determine the risk for park-goers, Heilman said.
"But we wanted to make sure because the state couldn't test right away," she said.
The Department of Health and Mental Hygiene's test July 29 again confirmed the presence of microcystin. However, state officials gave boat rentals the green light once again, as the reservoir's toxin levels were not high enough to be harmful to boaters, though a risk still existed for those who might ingest the water, Heilman said.
"If we had a swimming beach it might be different," she said.
Microcystin can cause a mild rash, and if ingested, gastrointestinal issues. Pets suffer the same symptoms, and in rare cases, pets have died due to liver damage.
Park officials posted extra signage warning visitors, Heilman said, but in any case, no one, including pets, should swim in the reservoir, per park regulations. Privately owned canoes and boats could still be brought out onto the lake when boat rentals were closed.
Jeff Degitz, administrator for the county's Department of Recreation and Parks, said that he could not comment whether boating rentals have declined in the past following water advisories.
Degitz said that county officials try to alert residents as soon as possible when the advisories end.
"We try to get the information out when conditions do improve," he said.
The popularity of the park is unaffected, Degitz said, and has he never received any complaints regarding the boat rentals.
"There's a lot of things to do, picnics, renting pavilions, going to programs at the nature center" he said. "So while a boat ride may be part of someone's plans for the day, there's certainly plenty to do."
Algae blooms are not a new issue for Piney Run, Heilman said. Like clockwork, during the late summer or early fall, park officials would alert Heilman or her department to a visual increase in the amount of algae on the lake. In 2009 and 2010, Piney Run closed boat rentals following tests that found algae blooms had produced toxins, though the algae was not the same species as July's bloom. Heilman said her department did not observe any blooms in 2011 or 2012.
Any changes in Piney Run's watershed, which encompasses a 6,400-acre area, can stimulate an algae bloom, Heilman said. She encourages holistic practices for locals: planting trees, avoiding chemical lawn treatments, and not allowing pets to defecate by streams, all which could be preventative for future blooms.
Heilman guessed this year's bloom was likely caused by repairs to the nearby dam, which occurred around the time staff saw the visual increase in algae, and also altered water flow to the lake.
A chemical treatment is available, but is only applied if the affected body of water is used for drinking water and needs immediate attention. Presently, the reservoir functions as a recreational facility, and for flood control.
Officials will continue to monitor the water for any changes, Heilman said.
"We just want to play it safe," she said. "For the safety of the park patrons."