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The Carletonian

The Carletonian

Lyman Lakes undergoing shore restoration

<rleton decided to restore the shorelines of Lyman Lakes in 2000, the project was supposed to last decades. Now, nine years later, the lower of the two lakes near Goodhue Hall is nearly back to its normal water capacity after a second re-shoring effort that began this summer and should near completion some time next week.

“We’re going back and essentially redoing something that should’ve been done in 2000,” Superintendent of Grounds Dennis Easley said.

A plan laid out by the Minnesota Department of Natural Resources (DNR) for the 2000 restoration counted on the emergence of vegetation from the lake bottom to slow erosion — vegetation that never appeared. Since then, the shore on Lower Lyman’s Mai Fête Island, a common recreation area for students, has eroded eight to ten feet, mainly due to wave action.

“At that rate, we were going to lose a lot of the island,” Easley said. “Environmentally, this needed to be done. It seemed to be speeding up.”

Prairie Restorations, a company based in Princeton, Minn. that has worked with Carleton and the Arboretum for 30 years, began work on the project Aug. 12. The plug was pulled on the lower lake’s culvert to dry it out before building a protective wall along the shore.

Students on campus during the drying stage found items ranging from bike parts to Frisbees on the lake bottom, though “there was not a great accumulation of stuff,” Easley said. “In the past there was lots of stuff because it had been decades since we’d dredged them.”

Financed with money designated for the project from facilities funds, the actual re-shoring process involved the use of biodegradable fiber sacks filled with yard-waste composted material from Resource Recovery Technologies, the same company that works with Carleton’s food-waste compost.

“Some of the stabilization techniques are fairly recent,” Easley said. “We’ve gotten smarter since 2000, and so has the DNR.”

Plants placed into the compost will have established roots by the time the sacks biodegrade, presumably holding the soil in place for several decades, which Easley calls a “permanent fix.” Various forms of local prairie vegetation were chosen based on suggestions from the Arboretum staff to replace areas on Mai Fête’s shorelines previously covered in mown grass.

Completion of the project was originally planned for before students returned to campus, though Easley said a mandatory 30-day period for public response and rains in early August delayed the process. Minus some final work on the island, the project is basically completed, though fences will remain around the shoreline for about a year to protect new plants from the ever-present Carleton geese.

Workers re-plugged the lower lake’s culvert last Thursday, but it has risen more slowly than expected, possibly due to new storm retention ponds upstream on Spring Creek, which flows into Lyman Lakes. As of Tuesday, the lake was half full, and Easley expects it to be at full depth, with water spilling over the dams, by next week.

“A couple good rains should take care of it,” he said.

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