WINDHAM — A forum hosted by the Highland Lake Leadership Team provided an update on what researchers and water quality specialists know – and don’t know – about the mysterious bloom that has temporarily appeared in the lake over the past four summers.

“Things are fairly inconclusive in terms of what’s going on in the lake,” said Karen Wilson, a professor in the University of Southern Maine’s Environmental Science and Policy Department, at the March 21 forum held at Windham High School.

Wilson explained that the likely culprit behind the bloom has been identified as a form of cyanobacteria, also known as blue-green algae. But Wilson, who used the term picocyanobacteria to denote the organisms’ small size, said that the source and specific type remain elusive.

“We don’t know the full identity and source of the picocyanobacteria that we think are causing the bloom,” Wilson said. “We know that they’re picocyanobacteria, but we don’t know necessarily where they’re coming from – we don’t know what species.”

At least 70 people attended the science forum last week, which had to be rescheduled from its original March 7 date because of snow. The public forum followed a December roundtable with various scientists, researchers, and experts which was hosted by the lake association and closed to the public.

Last week’s two-hour public meeting featured several presentations: an overview of the lake watershed and its history from Maine Department of Environmental Protection environmental specialist Wendy Garland, a description of the lake’s ecosystem from Wilson, and insight on how property owners can help protect the watershed from Heather True of the Cumberland County Soil and Water Conservation District and Windham Stormwater Compliance Officer Gretchen Anderson.

Garland outlined past efforts to bolster the lake’s health, noting that the lake – which is primarily located in Falmouth and Windham, but touches into Westbrook – was removed from the state’s list of impaired water bodies in 2010 after years of collaborative efforts.

“These water quality problems are real, and there are solutions, and your hard work in the past has paid off,” Garland said. “And we’re trying to look at the challenges that lay before us, and refocus our energies on the next challenge ahead.”

True and Anderson offered suggestions on how property owners can minimize their impacts on the watershed, particularly how they can reduce the amount of nutrients such as phosphorus and nitrogen that find their way into the lake.

Those suggestions include adding vegetative buffers to lakeside properties to decrease runoff, eliminating or reducing lawns, using phosphorus-free fertilizer, maintaining and adding filtration measures to roadways near the lake, and regularly maintaining septic systems.

Wilson said that the various experts working to understand Highland Lake’s bloom have offered several suggestions on where the research should go next.

Areas slated for additional study include learning more about the physical structure of the lake and nutrients within the watershed, confirming the species of cyanobacteria and whether or not it’s associated with toxins (so far, there’s been no evidence of toxicity, Wilson said), and building on the lake association’s existing water quality testing with an emphasis on timing and location.

“The focus for this summer is to get the timing and location of the sampling in the right place at the right time, with all of these different parts,” Wilson said.

Researchers are also looking to track changes within the lake’s food web, including the smaller phytoplankton and zooplankton as well as the fish population.

Bill Walker, who serves on the Windham Planning Board, asked the panel how local policymakers and the lake community can “rule out what’s noise in the process” and determine the critical aspects of the issue in which they should be working together.

“We know phosphorus is going to play a role in what’s going on,” Garland said in response, adding that the updated Highland Lake watershed survey planned for May 19 will include an effort to identify erosion sources.

Town Councilor Jarrod Maxfield highlighted actions taken by the council in an effort to protect Highland Lake.

“We have taken some dramatic steps to help protect the lake,” Maxfield said. “In my opinion, it’s now time for the watershed – for you guys to pick up that ball and run with it.”

In February, the council voted 6-1 to extend an existing moratorium on development in the Highland Lake watershed for another six months after first passing the measure in September 2017. Some members of the public have raised concerns about the moratorium, saying it has negatively impacted their development plans.

Falmouth Town Manager Nathan Poore attended the March 21 session and addressed a question about what his town has been doing to help protect the lake. He noted the creation of the Highland Lake Leadership Team, which includes members from both towns.

“We are not necessarily seeing the same development pressure (as Windham),” said Poore, who didn’t rule out a retroactive moratorium for the Falmouth part of the lake watershed. “We have had our eye on it. There isn’t a moratorium in place, but we’re ready to go with it if we start to see that pressure.”

Poore also said his town is going to join Windham in financially supporting the lake association’s water testing efforts. Windham provided $4,000 last year, and Poore said Falmouth will be allocating $5,000 to the testing this year.

Matt Junker can be reached at 781-3661 ext. 123 or mjunker@theforecaster.net. Follow him on Twitter: @MattJunker.

Wendy Garland, a Maine Department of Environmental Protection environmental specialist, gives a presentation during at a March 21 forum on Highland Lake at Windhan High School.