Algae floats on the surface of Moores Lake Tuesday afternoon. (Delaware State News/Matt Bittle)
DOVER — Earlier this month, Thomas Hengst went down to Moores Lake, as he does nearly every day, expecting to find the usual photogenic setting, a refuge from urban life that attracts many fishermen.
Only this time, things were different.
The shallow lake, which covers 27 acres on the Dover-Camden border, curves through the trees, with a number of houses sitting on the shore. At one end, water flows down a small dam, right next to the parking lot where visitors often come to fish or just sit by the lake.
Mr. Hengst, who lives next to the lake, frequently brings his fishing pole and camera, enabling him to catch and release fish and to take photos of what can be a picturesque setting. Sometimes he canoes on the lake, which used to be so clear you could see the fish swimming below, he said.
He expected more of the same on this evening, around July 11.
Thomas Hengst holds a clump of algae from Moores Lake last week. (Submitted/Thomas Hengst)
Instead, the lake was covered in algae, a mass of green that threatened to hog the oxygen and choke the fish and plants living in the water.
Algae are simple plants that can range from the microscopic (microalgae), to large seaweeds (macroalgae), such as giant kelp more than 100 feet in length.
“It was heartbreaking to go down there and take pictures of the sunset and not have a reflection at all,” Mr. Hengst said.
In recent days, fishermen have come to the lake only to find it unfishable, leading to them leave almost as soon as they arrive, Mr. Hengst said.
This is the first time Moores Lake has found itself in such dire straits, according to the Department of Natural Resources and Environmental Control.
To combat the pond scum, DNREC deployed two of its harvesters, large machines a DNREC information sheet compares to lawn mowers. The harvesters move through the water collecting algae and other harmful vegetation near the surface.
DNREC never before has had to use harvesters to remove algae from Moores Lake.
After several hours of cutting up algae and removing it from the lake on Tuesday, DNREC workers returned Wednesday.
Over the course of the two days, 264 cubic yards of algae were removed, with about 70 percent of that coming on the first day.
While that may sound like a lot — and it is for Moores Lake — it pales in comparison to the 3,552 total cubic yards of plant and algae mass collected from lakes and ponds last year.
DNREC’s Fish and Wildlife Division oversees 34 ponds, using revenue from fishing licenses to clean the bodies of water when the need arises.
On Wednesday, a pessimistic Mr. Hengst described what he observed the previous day.
A DNREC worker uses an aquatic vegetation harvester. Similar equipment was used to remove algae from Moores Lake. (Submitted /Department of Natural Resources and Environmental Control)
When DNREC left Moores Lake Tuesday, the environment was looking better, but the algae soon began to clump together again and cover the lake’s surface, he said. DNREC’s Mike Stangl said parts of the algae began to break into small pieces and drift into shallow water, making it difficult for the two harvesters to remove more of the material.
After returning Wednesday, workers were able to clear up more of the lake, leaving the boat ramp open.
“There is much more open water for anglers to fish,” Mr. Stangl, freshwater and anadromous program manager for the Fisheries Section, said Wednesday afternoon.
The algae’s rise likely can be traced to nutrient runoff. Nitrates and phosphates from nearby residential and natural areas spill into the lake, causing algae to bloom. Animals also could have tracked the algae into Moores Lake, as could boats with bits of the vegetation stuck to them, Mr. Stangl said.
Although the agency knew the pond scum plaguing Moores Lake was a type of filamentous algae, biologists still were trying to determine the exact type, he said. Lyngbya, a common type of algae, had been ruled out.
Some uncertainty remained as to both the cause and the solution, Mr. Stangl noted, explaining DNREC had to be careful to avoid clearing out the algae only to have “something come in and take its place.”
Time will tell if the lake fully recovers from the pond scum that so troubles Mr. Hengst. He fears the algae will continue to afflict Moores Lake, as small clumps drift together and clog up the water.
“They’ll never get rid of it. It’ll be here every year,” he said sadly.