Ten-year-old Blake Walls, of Middleburg, screamed as he quickly spun the reel of a heavily bent fishing rod.

“I got one!” he yelled – loud enough that people on the other side of the small Union County lake looked up, expecting a monster catch based on his reaction. Instead, he pulled from the water a wadded mass of green algae – more resembling something retrieved from a shower drain than a freshwater lake.

Suddenly, the mass moved. Buried under a thicket of matted algae was a small panfish.

Anglers and kayakers have dealt with algae on this one specific lake in the past, but never as early as Memorial Day weekend. Nearly half the lake was covered in what appeared to be a heavy green opaque plant-based oil slick.

“Commonly, the highest risk for significant algae coverage comes in the late summer and fall, but there is documentation and reasons for it to occur year-round,” said Nick Decker, of the DCNR State Parks system.

Mike Parker, spokesman for the Fish and Boat Commission, admitted that an increase in algae sightings this early may be at least partially due to an increase in outdoor recreation during the COVID-19 quarantine situation.

“As far as official data on algae, are we seeing more? I’m not sure, but there are so many more users out there – more people fishing. This has been common during trout season, where we are getting more reports from people of things they don’t understand,” he said. “Someone who fishes a lot and is used to seeing aquatic vegetation may consider algae par for the course, but others who are just getting out more now due to the circumstances may notice a situation, think something is wrong and act on that.”

Algae itself is an important part of the aquatic ecosystem.

“It is the base of the food chain – there are a lot of benefits that come from its ability to photosynthesize and offer so many other sources to feed from,” Decker said. “A certain amount is important to sustain the balance of things – we are definitely not trying to create an algae-free environment.”

But an abundance of algae can cause quite a few issues, including recreational strife for those who enjoy fishing, boating and swimming.

“Not everything in nature is pretty, and it definitely isn’t convenient to head to the lake hoping to catch a fish, but instead reeling in a glob of stuff on your lure every time,” said Parker.

“From a recreational standpoint, the main negative outcome is the inhibition of intended swimming in a beach area affected by algae or use of boat ramps,” Decker added. “However, in our work with the state parks, the No. 1 issue with an increase in algae is ecological.”

A layer of algae floating on the surface blocks sunlight from entering the water, prevents photosynthesis and hampers the amount of dissolved oxygen beyond the surface of the waterway.

“It can definitely provide a threat to the warmwater species such as panfish, minnows and other foraging species that bigger predators go after,” said Parker. “Not too often are there fish kill situations involving large bass – it is typically panfish that head out to shallow areas to spawn and nest and there is an oxygen depletion situation.”

Algae in its simplest form, according to Decker, can ride a fine line between being a plant and bacteria.

“True algae is a form separate from aquatic vegetation, but there is also cyanobacteria – also known as blue-green algae (or blue algae) – that can be a definite concern because of toxins it produces,” he said. “Basically, there are three categories – true algae, plant-based algae and cyanobacteria.”

He urged caution around all three types.

“To be completely frank, any kind of algae condition can increase risk for potential health outcomes,” he said. “A true algae can cause dermal irritations, especially if you have sensitive skin. Plus, something that may seem to be a true algae may be something else. Cyanobacteria causes toxins that can be dangerous to people and especially dogs.”

A bloom of cyanobacteria sparked news coverage late last summer at Frances Slocum State Park in Luzerne County, as park staff warned visitors that the blue algae could cause illness, and even death, in dogs.

“Our department is not aware of any reported cases of illness in livestock or pets this year, however we had anecdotal reports of dogs that succumbed to cyanotoxins last summer,” said Shannon Powers of the Pennsylvania Department of Agriculture. “Among domestic animals, dogs are most susceptible to a toxic waterbloom. This is due to their preference for swimming and drinking in dense waterblooms and a greater species sensitivity to the cyanotoxins, especially neurotoxins.”

Algal poisoning is an acute, often fatal condition caused by high concentrations of toxic blue-green algae in drinking water as well as in water used for agriculture, recreation and aquaculture, Powers added.

“Fatalities and severe illness of livestock, pets, wildlife, birds and fish from heavy growths of cyanobacteria waterblooms occur in almost all countries of the world,” she said. “Acute lethal poisonings have also been documented in people.”

Algae blooms are typically caused by warm, sunny weather combined with nutrient-rich water, which is why most algal issues are reported during warm seasons when blooms are longer-lasting and more intense. An increase in algae can also be a sign of nutrient overload that many times is contributed to the agricultural community.

“The runoff of fertilizers and animal wastes can promote nutrient enrichment and contribute to – and intensify – a waterbloom formation,” said Powers. “There is also evidence that supports the observation that global climate change is causing earlier, more intense and longer-lasting warm weather that leads to more extensive waterblooms of cyanobacteria.”

Knowing the differences in algae can be a good first step in preventing an issue for you and your family, according to Decker.

“Once you have a trained eye for it, you can distinguish slight distinctions in colors,” he said. “Cyanobacteria is more fluorescent than true algae, and obviously cyano has more of a blue hue. It is also important to understand that algae is not always occurring at the surface. Even if you are not seeing the condition on top of the water, it may be under the surface.”

Efforts to prevent blooms include flow maintenance in regulated rivers, according to Powers, along with water-mixing techniques to eliminate stratification (where things collect together) and reduce nutrient release from sediments in reservoirs. Certain algicides can improve conditions in dedicated water supply storage situations.

“Water treatment techniques can be highly effective to remove both cyanobacterial cells and cyanotoxins with appropriate technology,” she said.

Ultimately, algae issues in Pennsylvania provide yet another example of why watershed management is important, and how we can all be connected through those efforts.

If you notice an algae situation that seems excessive somewhere within the Middle Susquehanna watershed, please report it to Riverkeeper John Zaktansky, by calling 570-768-6300 or emailing comments and photos to

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