During the particularly wet spring and summer of 2014, exposed soil at a construction project at Camden’s Snow Bowl ski area would wash down the mountainside into Hosmer Pond whenever it rained.

Residents were alarmed as storm after storm sent more muddy water into the pond, and many called for more oversight of the project. But the erosion continued into the summer of 2015.

By August of that year abnormal algae growth was reported in the pond, and the following summer, there was a full-blown algae explosion. An aerial photo of a massive green blob, which Maine Department of Environmental Protection estimated to be more than 2 acres in size, ran in newspapers at the end of May 2016.

“The town should have stepped in and said ‘Oh my God, this is a total emergency, and we should throw resources at it and nip it in the bud,’ Lee Schneller Sligh, a volunteer lake monitor who lives on the pond, said Feb 8, "They had opportunity after opportunity to do that over the next year and a half, and they didn’t do it. Now we'll probably be scooping algae out of the pond for a decade.”

For one example of the environmental violations on the mountain, in notes from a June 24, 2015 site inspection provided by Sligh, Dawn Hallowell, regional license and compliance manager for DEP, wrote that she observed erosion of the access roadbed into Hosmer Brook, and an open unprotected ditch eroding into a wetland and settling ponds and then out into Hosmer Pond.

"This same ditch caused a siltation event in early June… Tried to explain to the town that this discharge was foreseeable and avoidable," Hallowell wrote, "Each discharge increases fines."

The town is currently in negotiations with DEP over enforcement actions for environmental violations during the project. But is it also responsible for the algae growth? DEP is investigating the possible link.

Sligh believes there is a connection.

“A lot of evidence has been presented that this has nothing to do with failed septic systems or anything like that. This is clearly on account of the sedimentation,” she said. “The town of Camden should be organizing removal efforts and footing the bill for this 100 percent.”

But Bill Buchholz, president of the Hosmer Pond Association and impromptu algae wrangler, is hesitant to claim the erosion is the cause. “We try to avoid assigning blame, it is important not to throw these assumptions around too loosely,” he said by phone Jan 4.

Though he said he's "never seen anything like" last summer's algae growth in the 30 years he has been living on Hosmer Pond, he said sediment runoff into the pond does occur on occasion. “We have seen that before, maybe not quite as bad [as during renovations], but over the years there’s been erosion from the mountain and it fills the pond.”

Buchholz could be seen on the pond last summer with a makeshift algae net attached to a barge, scooping out green slime by the bucketful. Removing the algae eliminates a source of nutrients — which become available in the water column as the algae decomposes — that would fertilize the next generation of algae.

Instead those nutrients are put to use on land. He dries the algae and distributes to gardeners as fertilizer.

“I would say I’ve taken 25 buckets from the blob this past week. Maybe another 15 from around the perimeter in the past two weeks,” he wrote to Sligh on Aug. 22, 2016, adding a week later, “I’ve removed another 18 buckets from the big patch.”

Jeremy Deeds, aquatic ecologist with the Lake Assessment Section of the DEP wrote in an email that while he knows of no other removal efforts for this type of algae in Maine, DEP granted a general permit to the Hosmer Pond Association to attempt manual removal because of the “extraordinary nature of the algae bloom" at the pond.

DEP did not comment on the ongoing investigation into the relationship between the algae growth and the violations at Ragged Mountain Recreation Area.

Meanwhile, the town suggested there were other possible causes of the algae growth besides the botched erosion control, such as leaking septic systems or over-fertilized lawns.

Members of Hosmer Pond Association looked for evidence of these things in July 2016 by testing water at six locations. If septic systems were leaking, the bacteria E. coli would be found concentrated near the leak, but E. coli was found to be “extremely low in all areas except where the pond abuts public land,” as reported in the association’s annual meeting minutes.

If fertilizer were running off into the pond, there would be a higher concentration of nutrients near the fertilizer application site, but the group found that phosphate levels, though high, “were consistent across all sample sites, indicating that no private properties were the source.”

After the aerial photograph of the algae blob ran in the papers, the town hired biologist Paul Leeper, an environmental consultant and executive director of the Megunticook Watershed Association to act as a liaison between the town, DEP and the pond association. He investigated possible causes for the algae growth, but said “there wasn’t a big smoking gun,” in a Feb. 8 interview.

The algae growing in Hosmer Pond is of a type that is common but not well understood. Unlike single-celled algae that is distributed evenly throughout a water body, turning the water green during blooms, the Hosmer Pond algae is of a class called metaphyton which forms stringy, slimy mats.

“If you snorkel around in August in a swampy cove in most any warm water pond in Maine you’d see these masses of metaphyton — that big slimy goop you see in backwaters,” he said. “It’s not uncommon at all, in fact it’s found in every lake and pond in Maine. It’s when you have an explosion of growth that you have problems.”

It typically forms in shallow areas with underwater vegetation. Sometimes the mats float to the surface when they fill with oxygen bubbles through the process of photosynthesis, according to a University of Southern Maine report.

While it is a nuisance to people who want to swim or fish in the pond, Deeds, of DEP, said the algae “poses no harm to the pond or humans that we know of. It is a green algae which does not produce toxins.”

And Leeper said that it has not yet negatively impacted the health of the pond: “There are fish in the pond, and there hasn’t been any evidence of oxygen depletion.”

Widespread problem

Increases of metaphyton growth have been reported in lakes and ponds throughout Maine in recent years, but its causes and effects are still a mystery.

According to its executive director Scott Williams, The Volunteer Lake Monitoring Program has been receiving “many, many calls” from the general public concerned about metaphyton and why there appears to be more of it lately.

He said it is hard to do any quantifiable studies on growth of the algae over time, and the information the organization has amassed is purely observational, but many people with long-term knowledge of particular lakes have been reporting last year’s metaphyton growth as the worst they've seen.

Williams said, “I’ve been a lake scientist for 35 years and I can say confidently that I am seeing more now than in decades past."

The growth is not linear — some years there’s more growth, some years less, he said, and in some lakes there is a significant increase.

Among the water bodies with increasing metaphyton, Hosmer Pond is an “extreme example,” Williams said.

Deeds, of DEP, also called the growth in Hosmer Pond “a unique situation.”

“Metaphyton is a common occurrence in Maine lakes, even in our most remote and undeveloped lakes, but we typically do not see [it] growing in the density that we observed in Hosmer Pond last summer,” he said.

“There’s a lot more that is not known about metaphyton than what is known," Williams said. "There is obviously a piece of the puzzle we don’t understand."

That missing piece is how the algae gets its nutrients.

Leeper said phosphorus is a limiting nutrient for plant growth in most freshwater systems, and that an increase in phosphorus is known to cause blooms of the more well-known single-celled algae.

He said that phosphorus that enters the water through soil runoff is chemically bound in the soil and not available for algae to use. Those bonds can be broken in the absence of oxygen in the “hypolimnion,” the deepest area of a lake that becomes oxygen depleted over the course of the summer as bacteria break down decaying organic material. When the surface water cools and mixes with the deep, cold water in the fall, the newly available phosphorus enters into the upper areas of the lake where light can penetrate. This is one way phosphorus that enters the water bound to soil becomes available to fuel single-celled algae growth.

Hosmer Pond is shallow enough that it is oxygenated all the way to the bottom throughout the year, so the metaphyton growing there must be getting its phosphorus another way, Leeper said.

Deeds said besides being carried into the water in soil, phosphorus can also enter a water body through streams and a minimal amount enters through atmospheric deposition.

But Williams said that unlike single-celled algae blooms, metaphyton growth is not correlated with high phosphorus levels. “We see substantial growth in lakes with low phosphorus,” he said. “We see it in lakes with very good water quality and lakes with not so good water quality.”

Climate change?

There are several possibilities lake scientists have suggested for where metaphyton is getting its nutrients and why its growth has been increasing lately.

One possibility is warmer springs seasons and early ice-out dates. USGS analyzed 163 years of ice-out data and reports is occurring "significantly earlier" than in the 1800s. Last year ice-out occurred in mid-March (March 16 for China Lake) for many Maine lakes — about a month earlier than usual. Williams said early thaw means warmer water and greater light penetration earlier in the season, two factors which will have a profound impact on lakes.

Some lake scientists suggest that early ice out gives metaphyton an ecological advantage over other types of algae for nutrients in the water. Others suggest that extreme rainfall events could affect not only runoff but groundwater flow into lakes, and that nutrients in groundwater could be entering the waterbodies through springs.

While the situation as Hosmer Pond is extreme, Williams said, "linking it to land use in the watershed is going to be a tough case to be made.

"There could be a relationship," he said, “but there are most likely other factors at play as well."

But whatever the cause of the algae explosion, protecting the water quality of Hosmer Pond is a priority for the pond association and the town.

Buchholz said that although the association did not find any leaking septic systems or excessive amounts of phosphorous near private land, he knows that some people in the watershed still fertilize their lawns.

"That’s really a tough nut to break," he said. "It is important to realize if you fertilize your lawn next to a pond and it drains into the water, it will cause problems."

Leeper said the erosion problems on the former renovation sites have been dealt with, and that he has been working with the town to minimize runoff on other public properties around the pond, because every little bit will help.

“Typically with water quality in lakes and ponds," he said, rather than finding a single source, "it’s more death by a thousand cuts.”

Editor's note: An earlier version of this story misquoted Lee Schneller Sligh in the fourth paragraph and misspelled Bill Buchholz's name.

Courier Publications reporter Jordan Bailey can be reached at 338-3333 or by email at jbailey@villagesoup.com.