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Photo © Tabitha Walters

Poor Sister

Environmental challenges at Third Sister Lake

by James Leonard

From the August, 2018 issue

Third Sister Lake, in the U-M's Saginaw Forest off Liberty Rd., looks idyllic. But it's next door to the former Gelman Sciences facility on Wagner, and 1,4 dioxane from the now-closed factory has contaminated the lake and groundwater under the forest.

No one drinks that water, though, so it's not county water resources commissioner Evan Pratt's main worry. He says the real danger to the lake and forest comes from erosion and runoff. "There were soil erosion issues at the 2|42 Church site related to construction [in the former Gelman building] that have been resolved," he emails, but runoff remains a problem.

"Nutrients and salts have entered the lake via the small but highly eroding stream channel that runs through the forest," emails U-M School for Environment and Sustainability prof Bob Grese, who chaired a SEAS committee overseeing the forest. "The runoff in this stream is very flashy and empties considerable sediment into the lake each time it rains. It changes the whole ecology of the lake when the water doesn't turn over. The saline and sediments have increased the nutrients in the lake, spreading invasive species like those at the east end."

If the runoff isn't addressed, Grese warns, Second Sister Lake will develop "broader bands of disturbed wetlands around its borders, sections of trails in Saginaw Forest would likely need to be abandoned or rerouted as erosion becomes more extensive, and invasive exotic species would likely become more dominant in Saginaw Forest and around the lake."

Grese says addressing those problems will require collaborative planning among the U-M, the county, and neighbors. "Right now, there are no plans in place," he writes, "and my suspicion is that it will take considerable effort to bring all the players together to make this happen."

Neither the dioxane or the runoff poses a danger to nature lovers hiking in Saginaw Forest. But until recently, traffic did: visitors had to cross busy Liberty Rd. on foot to get there.

That problem, at least, was easily solved. Thanks to Mark Smith, who's building a live-work neighborhood on either side of the woods ("Ground Zero," March), signs on Wagner Rd. now direct visitors to the 2|42 Church parking lot, where a trailhead leads into the woods.