AUBURN — Watershed officials will work with city and state public crews over the next few weeks to head off potential erosion problems around Lake Auburn.
The goal is to get the work wrapped up before winter, hoping to cure potential algae problems at the lake, according to Sid Hazelton, district engineer for the Auburn Water District.
“Some of our preliminary data pointed out some areas we should fix immediately to limit phosphorous that could get into the lake from different sources,” Hazelton said.
Hazelton said the work is targeting erosion at three areas: the southwestern corner of the intersection of Route 4 and Lake Shore Drive, the foot of the hill on North Auburn Road between Holbrook Road and Hersey Hill Road and a channel along Whitman Spring Road.
“Those are three potential areas where some work is needed to stabilize some culvert outfalls that have caused erosion and have been washing material into the lake,” he said. “These type of things certainly contribute to phosphorous input and these three projects are the most obvious and ones we felt were priorities to take care of now.”
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 an algae bloom, triggered by high phosphorous levels in the lake. But officials did not know why phosphorous levels had increased.
Phosphorous and warm weather encourages algae to grow. The algae eventually dies and sinks into the lake, decaying and using up oxygen in the process. That asphyxiates the trout, which prefer the cooler bottoms of the lake in the summer.
The Lake Auburn Watershed Protection Commission kicked off a monitoring program in the spring designed to stop future algae problems before they started. Strategies called for more water testing around the lake and using an algae-killing copper sulfate to halt any new blooms.
Water quality tests this summer have showed a healthy lake that seems to be recovering from last summer’s algae bloom. Visibility levels so far in 2013 have been much improved compared to both 2012 and 2011, and the algaecide has not been needed.
But the response also called for a survey of the land around the lake, looking for possible soil erosion that could have put phosphorous in the lake.
Hazelton said that final watershed survey is expected this winter, but early reports pointed to problems at those three areas.
Crews from the Maine Department of Transportation should begin working Friday at the intersection of Route 4 and Lake Shore Drive. It’s an area maintained by the MDOT, where culverts go under the road and dump near the lake. Crews will be adding erosion resistant fabric, rocks and mulch along the road between the Route 4 and the lake to stabilize the channel.
“They’ll probably bring in some fill material too, to bring this eroded ditch up to grade,” he said. “They’d slope back the sides to make it blend in.”
Auburn Public Works crews should begin installing a new channel along North Auburn Road. That channel will steer road runoff away from the lake.
“There is a culvert that goes under North Auburn Road and discharges in a field,” Hazelton said. “It’s causing some scour there, and it’s eventually getting into the lake.”
And water district crews have been working along Whitman Spring Road.
“There is drainage that comes along a large area through the forest,” he said. “It’s kind of a continuing project, and it’s quite extensive.”
The work involves adding rock to stabilize the channel.
“That channel keeps transporting sediment and digging into the ground carrying gravel and dirt into the lake,” Hazelton said. “We are armoring this channel so it will stabilize the ground so it can accept the water as it comes down the channel.”
Send questions/comments to the editors.
