Scientists still looking for source of Torch Lake algae

Linda Gallagher, Contributing Writer

Courtesy photo

Three Lakes Association member Rick Doornbos and TLA Water Quality Chair Becky Norris are shown collecting samples of Golden-brown algae from Torch Lake in June. First identified in 2014, the presence of the algae in the (until now) pristine waters of Torch Lake is a concern to both scientists and riparian property owners.


REGION – In 2014, property owners and visitors to Torch Lake began to notice that the sandy shoals of the lake were becoming covered with a fluffy, brownish substance. And the famous color of the lake, an intense turquoise blue, had more of a greenish tint, especially in shallower areas.

"Although it's hard to know exactly when that began, upon reflection some people have guessed that these changes had started as much as 10 years before," said Becky Norris, a longtime resident of the Torch Lake area and water quality chair for the Three Lakes Association (TLA). The TLA is a grass roots volunteer organization comprised primarily of riparian lake shore property owners dedicated to preserving the environmental quality of Torch Lake, Clam Lake and Lake Bellaire.

It was soon determined that the brownish substance was actually a type of non-toxic algae known as "Golden-Brown Algae," or GBA, which is common and present in many bodies of water in northern Michigan, according to Norris.

In 2015, the Three Lakes Association began to investigate the GBA with consultants Rex Lowe of the University of Wisconsin, and professor emeritus from various schools; Pat Kociolek, a professor at the University of Colorado; and Michigan State University professor Jan Stevenson.

"One obvious fact,” said Norris, “that the diatoms making up the algae would increase their growth in response to an increase in nutrient supply – has guided our investigations. So far we have concentrated on water-borne sources as the primary possible source, the actual composition of the algae, and how it changes over the growing season.

"We have been looking at the levels of the most relevant nutrients, phosphorus and nitrogen, in lake water as well as in the groundwater that wells up into the floor of the lake," she continued.

"As the one most critical nutrient for growth in our area is phosphorus, which is generally bound to soil, depending on the soil composition's and its remaining capacity with exposure over time to nutrient-laden water, that led us to put aging septic drain fields on our list of possibilities as a causative agent for the algae."

But the research has not been able, as of yet, to determine with certainty where the nutrients are coming from, she cautioned.

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