Ah, the traditions of a Pittsburgh summer: fireworks, drives to Page Dairy Mart ... and massive algae blooms in Schenley Park's Panther Hollow Lake.
Each summer, the surface of the kidney-shaped pond erupts with thick green muck -- algae whose growth is fueled by high levels of nutrients in the water. Such blooms are not uncommon in lakes and ponds, but in Schenley Park, they are partly caused by another seasonal local attraction: the park's Bob O'Connor Golf Course.
As with many golf courses, the greenery is sprayed with chemicals to keep the grass lush. But those chemicals end up in the groundwater, and often spill into the pond.
"The golf course uses fertilizers and pesticides, and that's what's sort of feeding into the water and creating these algae blooms," says Mike Gable, the city's deputy director of public works.
"It's an ongoing problem," says Oakland resident Steve Pellegrino, whose home on Oakland Square overlooks the park. Left unchecked, the blooms "will kill everything in the lake."
Indeed, "Ponds covered with algae have very little biological activity," says Philip Gruszka, director of park management and maintenance for the Pittsburgh Parks Conservancy. "They're usually at the last stage of life as a body of water."
The golf course is trying to minimize its impact. "We are already doing very, very low applications" of chemicals, says Marc Field, executive director of The First Tee of Pittsburgh, the nonprofit organization that operates the course. "We want to work with the city to minimize the impact on Panther Hollow Lake. If anyone has suggestions to minimize algae blooms, we'll be happy to do them."
And in fairness, the golf course isn't solely to blame. While Panther Hollow Lake is man-made, and fed by Phipps Run and Panther Hollow Run streams, Gruszka notes that the lake's watershed is "fairly large," and includes most of Squirrel Hill. As a result, all kinds of pollutants drain into Panther Hollow Lake -- everything from dog feces and motor oil to lawn fertilizers and pesticides. What's more, the lake itself provides a veritable breeding ground for algae, which thrives in shallow, stagnant water that gets a lot of direct sunlight.
Gable says the city has previously dealt with the algae blooms in different ways.
Sometimes the problem "sort of rectifies itself," he says, since algae can be flushed out by heavy rains. Other times, the city treats the water with chemical "algicides." Algicides can kill algae blooms in just a day or two, but "I'm not in favor of using chemicals," Gable says. "If you use too much, it could affect the fish population."
So with help from the Parks Conservancy and researchers from Carnegie Mellon University, the city is looking for ways to keep pollutants from reaching the lake at all.
"We've got to fix everything up above before we fix things down below," says Gable.
Gruszka says the key is reducing water flows from higher ground. For example, "Meadows are extremely efficient at mitigating storm-water surface flows," Gruszka says. So the city has stopped cutting the lawn surrounding a Schenley playground on Bartlett Street, since few park-goers venture far beyond the equipment.
Another problem, says Gable, is that the pond's shores are made of concrete, which allows chemicals and sediments to spill directly into the water. "We want to [replace the concrete with] a natural wetland," he says. "Wetlands help filter out all the bad stuff."
But that's in the future, and Gable acknowledges, "I can't tell you we have anything planned" for how to deal with this summer's algae.
Locals are hoping the city finds an answer soon.
"I didn't expect to see this much [algae]," says Greenfield resident Jeff Roscoe, walking away from the muck-covered lake after fishing with his 14-year-old son, Giovanni.
"There's still a lot of fish in there," he adds, noting that most of the fish in the lake are pan fish, like bluegills. But "In August, [the lake] will be almost covered" with algae.
His son quickly adds, "Then you'll see a lot of dead fish."