ELLSWORTH — You’ve likely seen the photos: pristine lake waters transformed into murky, toxic green sludge, the result of a blue-green algae bloom. You’ve probably also read the articles, about how several dog deaths have been attributed to blooms in North Carolina and Georgia, and about how the blooms are increasing in frequency as waters around the world continue to warm.
So could it happen here?
It could, but it hasn’t yet, said City of Ellsworth Watershed Steward John Wedin.
“Blue-green algae is endemic,” said Wedin. “The key thing is they haven’t bloomed in our lake because our nutrient levels are low. Phosphorus is the limiting nutrient, so phosphorus is the key thing to focus on.”
Wedin said that although he’s never seen a blue-green algae bloom in Branch Lake, he has seen annual metaphyton blooms, which look “like cotton candy.”
Metaphyton is an entirely different group of algae and doesn’t produce toxins, according to the Maine Department of Environmental Protection (DEP).
Blue-green algae actually isn’t an algae at all — it’s actually cyanobacteria, a type of single-celled organism that is found naturally in all types of water, said Wedin.
When it “blooms,” blue-green algae grows to huge numbers, turning spots or entire water bodies particularly funky colors, from reddish brown to neon green. (One bloom in 2011 in Lake Erie could be seen from space.) It thrives in warm, still waters with high nitrogen and phosphorus levels.
With climate change and warming water, blooms are being seen increasingly farther north, including recently at a pond in South Portland.
“Every year has a different amount of rain, a different amount of nutrients, a different amount of heat,” said Public Works Director Lisa Sekulich. “All those things have to be ideal for a bloom to occur.”
Not all species of cyanobacteria (and thus, not all blue-green algae blooms) produce toxins that are harmful to humans, but it’s good practice not to swim in or recreate on water that looks scummy.
The toxins also can be particularly harmful for dogs, and their effect kicks in quickly, so it’s important to keep dogs away from the blooms and get them help as fast as possible if they ingest the water.
In recent months, members of the Branch Pond Association, a volunteer organization that helps steward the watershed, have raised concerns about whether the city knows enough about the water quality in the lake, particularly when it comes to blue-green algae’s favorite food: phosphorus.
“The function of government, in my mind, is to protect citizens. Part of the protection is protecting us from an algae bloom,” said David Edsall, president of the Branch Pond Association.
In a recent letter to the editor published in The Ellsworth American, Edsall wrote that the city is not doing all it should to prevent phosphorus pollution in the lake.
Edsall said he’d like to see more enforcement of best management practices when homeowners around the lake undertake construction projects (particularly alterations to septic systems, which can dump phosphorus into the lake), more inspection of boats going in the lake, more education and, in particular, more collaboration from city officials on keeping roads from eroding and shedding phosphorus-laden sediment into the water.
So what does the city do to protect the lake for drinking water and recreation?
Quite a bit, said Wedin, above and beyond what the state requires.
Staff members test both the lake and its tributaries every few weeks. They try and go out on consistent days (usually sunny and calm) in order to “compare apples to apples,” said Wedin, but also test on stormy days with thunderstorms and flash-flooding.
“We usually test for temperature and oxygen every time we go out on the lake,” Wedin said.
They test for total pH fairly frequently as well, along with any other tests the state requires. This year, staff members were asked to test for Coliform bacteria, nitrate, fluoride, herbicides, carbamate pesticides, inorganics and semivolatile organics, according to testing data provided to The American.
And they test for phosphorus, generally in the late summer or early fall.
“If you test under these worst case scenarios, which is later in the summer, when it’s warm, you get a more protective idea of the relative algae/phosphorus levels in the lake,” Wedin said.
Testing data show that under “quiet” conditions (clear, calm days), phosphorus levels in the lake are between 3 and 7 parts per billion.
Those are safe levels, said Wedin. “20 parts per billion is the common accepted standard for ‘uh oh, we could have a bloom at any time.’”
But the city has seen much higher levels, said Wedin, particularly in the tributaries after storms, when sediment is washing into the lake.
Under those conditions, Wedin has seen phosphorus levels up to 100 times higher than what would be enough to cause a bloom — between 150 and 200 parts per billion.
Most of the information is reported to the state, which keeps records of algal blooms, and is available online. The city does more testing than the state requires, so not all of it shows up on state websites, Wedin said.
Phosphorus is a key nutrient that exists in pretty much everything, from rocks to plants to us.
“It’s a key nutrient in every living thing,” said Wedin.
“We mine it from rock, we use it for fertilizer to give ourselves bigger and greener plants. The challenge is to not have bigger and greener plants in our lakes.”
There are a few ways to prevent that.
Failing septic systems are the source of between 5 and 10 percent of the phosphorus that winds up in lakes, according to the DEP.
Septic systems, even with maintenance, only work effectively for between 15 and 25 years. When they work properly, the leach field binds up the phosphorus, preventing it from flowing into the lake. Several of the systems around the lake are likely old and failing, said Code Enforcement Officer Dwight Tilton.
It can be expensive to replace a septic system, but the city offers a matching grant to residents whose septic systems are impacting the lake. Residents can fill out an application that can help defray the cost of the project.
But the largest contributor of phosphorus to the lake is poorly maintained roads that wash out and into the lake when it rains.
“It’s a problem at every single lake that is inhabited,” Sekulich said.
The majority of roads around the lake are privately owned. Edsall said private road owners often don’t have the expertise to properly maintain their roads and he would like the city to help educate them.
But city officials and staff say they simply can’t devote all of their time to Branch Lake alone.
“I think we have stepped up,” said City Manager David Cole. “The city’s been pretty aggressive about protecting the lake, as we should. It’s a valuable asset to the city, it’s our drinking water. Thirty-five percent of our paving budget this year has gone to roads in the Branch Lake watershed.”
As for enforcement of best management practices, staff urged homeowners to call the city if they see anything that looks amiss.
“To share the lake you have to have protections,” Wedin said. “It’s a compromise that everyone is party to, whether they realize it or not. Keeping the lake shore from being in the lake is the key thing. Everyone that lives around the lake is a partner.”