Can bacteria rescue lake bogged down by algae?

The two-acre lake at the center of Yardley Borough is the source of Nick Primola's favorite childhood memories. That's where he and his friends splashed one another from canoes and went exploring, where they skipped rocks on the water and fed the ducks, where they competed for fishing bragging rights.

So when Primola, 47, moved back to Yardley with his family five years ago, he was dismayed to find Lake Afton uninviting for canoeing or splashing. It was so covered with algae, it "looked like you could walk across it."

For three centuries, the lake has drawn nature lovers and strollers in the summer and ice skaters in winter. But in the last decade, muck has accumulated at the bottom and the water has become increasingly choked by algae, a problem inadvertently made worse after a 2012 street improvement project. Now, however, local preservationists say the tide is turning.

Last weekend, about 30 residents gathered to clean the area, sprucing it up for the warm-weather season.

They weeded and trimmed, picked up trash, and planted shrubs. And in June, the next fix will be added: an all-natural black dye that will act as "sunglasses" for the lake, shielding it from the sun, whose warmth encourages the growth of algae in the increasingly shallow water.

Friends of Lake Afton, a group that works to maintain the privately owned lake, is hoping such natural remedies work.

Every two weeks, the lake is treated with bacteria and enzymes, which will continue through the summer, said Michelle Sharer, president of Friends of Lake Afton. The group hired Clean-Flo, a West Chester company specializing in biological water restoration, last year; now the treatments are ramping up.

"In the long run, it will take longer maybe than using chemicals, but it's better for the environment, better for everything that lives out there," said Sharer, who with her husband became owners of part of the lake when they bought an adjacent house in 2008.

Neither Sharer nor Primola, the group's vice president, expected to become so passionate about the water when they each moved to Yardley -- "We've basically been turned into marine botanists," Primola quipped -- but they were lured by tradition, need, and natural beauty.

The lake was originally created for a grist mill at the start of the 18th century, and in the mid-20th century, half of it was filled in to create more parking for the borough. It has long been a "gem" in the center of town, attracting the public for all kinds of recreation.

More recently, Lake Afton has been attracting public interest because it began looking so swamplike, said Dave Bowker, a board member for the group.

"The key now is to turn that into improvements, quickly," he said.

The lake has not been dredged in decades, so sediment has accumulated at the bottom, cutting the depth nearly in half, Sharer said. The shallower the water, the more quickly it warms, and that's a boon to the algae. Left unchecked, the lake would eventually become a swamp.

The algae thrives on phosphorus, which has been found in the water in tests and comes from the dam that sources Lake Afton, Sharer said. The group also believes that increased runoff from nearby homes draining into the lake -- a result of the 2012 improvement project on Afton Avenue -- has contributed to the growth: Common lawn treatments include phosphorus.

Because the lake remains privately owned by multiple parties, funding to remedy these woes presents an unusual challenge. "We can't expend borough money on the lake ... since it's a private lake," said borough manager John Boyle.

If it were a public body, officials would be able to apply for grants or other funding for the upkeep. The possibility of leasing the lake to the borough has been discussed but hasn't come to fruition, Boyle said. Sharer is now looking into a conservation easement to open more funding opportunities.

Dredging would be the quickest remedy, but that can cost $500,000 to $750,000, Sharer said. So instead, they have turned to the cheaper natural treatments.

The group raised $10,000 for new aerators last year, which made a small difference but cannot fix the problem alone. This year, the group needs $15,000 to $20,000 for the treatments and regular maintenance, Sharer said.

A fund-raiser was held at a local business last week, and another is scheduled for next month, along with activities on Yardley's 50th Harvest Day, an annual festival, in September.

But already, Bowker said, the lake should begin seeing less algae this year, although major improvements will take time.

"We're definitely probably in the best place we've been I can ever remember for potential improvements," Bowker said. "We're on the cusp of, I think, a lot of good things."

For Primola, the efforts to restore the lake are about paying it forward to his kids' generation. He'd like to be able to hold canoeing and paddleboating, cocktail hours, and, of course, fishing contests.

"To have something like that that you're not really fully able to use and appreciate is kind of frustrating, knowing, as I know and many others do, what it once was," he said. "Many kids have no idea the simple joy they could get out of that."