AUBURN — Researchers may drill into the soil beneath Lake Auburn to find out whether a 2012 trout-killing algae bloom was part of a pattern.

University of Maine earth sciences professor Steven Norton hopes to drill out a core of soil at Lake Auburn’s deepest point this winter, Auburn Water District Superintendent Sid Hazelton said.

“We’ve learned a lot, and the lake has been very good and clear, by historical standards, since (2012),” Hazelton said. “But now we want to look for trends to figure out if 2012 was an anomaly, or if it’s something that’s happened again and again for years.”

Previous core sample have been no more than 30 centimeters deep, Hazelton said. That’s almost a foot. Future cores would go about three times deeper, he said.

“We did some basic core samples around the lake, but none of them have gone very deep,” he said. “What we are looking at now is a second phase, really getting down deeper into the lake.”

The Lake Auburn Watershed Protection Commission voted Wednesday to move forward with the second phase.

Water quality officials discovered more than 200 dead trout along the shore or floating close to the shore in mid-September 2012. They blamed the kill on high phosphorus levels in the lake.

Phosphorus in the water encourages algae to grow, using up available oxygen in the water and suffocating fish. The effect is especially notable in the cooler water at the bottom of the lake, where trout like to be in the hot summers.

According to a commission study, heavy rains in 2012 and warm weather later in the year made the algae bloom worse. The study noted that rainfall in 2013 was about 8 inches below the seasonal average, and that the fish-killing algae bloom did not return.

The study outlined about 35 places around Lake Auburn and its feeder tributaries that could be improved to keep soil from eroding and polluting the water.

The district received state and local approval to use copper sulfate to interrupt algae blooms if they occur again, but that has not been necessary, Hazelton said.

Norton’s testing could show whether excess phosphorus came from the watershed or from some other source.

“There are a number of things we can do to help keep it from happening,” Hazelton said. “We can do erosion control along the watershed and stay vigilant and make sure we control what gets in from the watershed.”

Hazelton said the work should cost less than $25,000. The researchers would prefer to do the drilling when the lake’s ice is strong enough to support their drilling equipment.

“The cost and complexity of doing all this on open water is very different,” Hazelton said Friday. “We just hope their preparations can coincide with the conditions of the ice on the lake.”

But Norton said Saturday that the testing will likely wait until May because of the forecasted conditions of the ice. Researchers will use a raft on the lake to steady the drill if do the work then, Norton said.

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