TRAVERSE CITY — Volunteers studying increased growth of golden-brown algae on Torch Lake’s floor will test for indications of a human vice: caffeine.
“The deer and the turkeys and what have you don’t drink coffee, and people do,” said Becky Norris, the water quality chair of Three Lakes Association.
Volunteers from the Three Lakes Association and researchers from state universities are trying to determine the source of golden-brown algae that became noticeable on the lake in 2014. They released results of last summer’s research into the grungy growth in April.
Algae grows better when more nutrients like phosphorus and nitrogen are available. Researchers suspect those nutrients come from agricultural runoff or leaky septic systems.
Last summer’s water samples showed what is apparent from Torch Lake’s crystal reputation, Stevenson said. There are few nutrients in the lake and the groundwater that feeds it.
“That means any increase in nutrient concentrations can generate an increase in the amount of algae in the lake,” he said.
Changes in algae mean there are changes in the lake, said R. Jan Stevenson, co-director of Michigan State University’s Center for Water Science. The algae is ugly enough to endanger Torch Lake’s reputation for Caribbean blue waters, and it could point to water quality threats.
“We are concerned that the golden-brown algae, the appearance of the golden-brown algae, is an early warning indicator of septic system contamination of the lake and potential changes in the lake that people will not want,” Stevenson said.
Caffeine in the groundwater that flows into Torch Lake would indicate septic systems are leaking into the groundwater, thus into the lake. Researchers also will test for estrogen, a hormone commonly found in birth control, and boron, an ingredient in household cleaning products.
“If people drink coffee and they use their toilets and flush, then you’re going to have caffeine going out to the septic distribution fields,” Norris said. “If we find caffeine in the groundwater that’s a pretty good indication that we do have some spread from a septic distribution fields.”
Norris compared old septic distribution fields to wet sponges. When they’re full, they leak.
“If it isn’t saturated you can put more water in it,” she said. “Once it’s saturated and you put more water in it, the water seeps out.”
Researchers will study the temperature of lake water and groundwater to see if the areas groundwater seeps into Torch Lake match where algae grows, Norris said. Three Lakes Association members tried to use infrared drone footage to track temperature change, but the pictures didn’t indicate changes.