Among many possible futures for Lake Michigan communities such as Evanston, one especially likely prediction is a life plagued by excessive flooding, overwhelmed sewers, vicious waves and shrinking beaches.
But in another feasible future, the shores of Lake Michigan are lined with dune grass, creeping juniper, silverweed, thistle, dwarf lake irises and dozens of other plants, grasses and flowers. The Lakefill becomes more than just a well-trimmed green lawn. While students and Evanstonians still have plenty of space to sit, walk and enjoy the lake, they also get to see a thriving ecosystem of native vegetation and migratory birds and butterflies just bordering the shore, absorbing rainwater and buffering flooding, making the earth too strong for the lake to eat away.
“Living landscapes do a great job of managing the shorelines,” said Ethan Brown, the resilience coordinator at the Alliance for the Great Lakes. He says that making the shoreline green again could address many issues of public health and safety.
As flooding and erosion threaten the Lake Michigan shoreline over the coming years, living landscapes could help preserve Evanston's beaches and a vibrant ecosystem, while saving lakeside residents millions in property damage.
Specifically, Brown proposed “living shorelines,” planting native vegetation along the water’s edge and then planting native dune grass to hold in the sand.
Living shorelines are known to control erosion, absorb flooding, increase resilience to the impacts of natural disasters, filter pollution and provide habitat, but a study published in November shows that they also have a capacity to sequester carbon, offsetting some of the emissions from other areas.
Since Chicagoans could face more heat in the future than Texas does today, according to a study published in January, that emission offsetting may be an upcoming priority.
Conserving native vegetation is critical to the Great Lakes overall ecosystem, Brown said, because vegetation holds the earth together, absorbs excess rainwater, and provides habitat for various key species, such as geese, loons, bald eagles, monarch butterflies and various bats.
With climate change looming, bringing increasingly extreme weather and various threats to the lakeshore, Brown says that conserving native vegetation is more important than ever.
Experts have noted increasing rainfall over the Great Lakes area in the past few years, which has caused flooding in surrounding communities, said Debra Shore, commissioner of the Metropolitan Water Reclamation District of Greater Chicago.
“No local sewer system can accommodate the kinds of intense rainstorms that we’re seeing,” she said.
An overwhelmed sewer system is a pretty obvious threat to public health. Flooding can push sewage into waterways that feed into the Great Lakes, according to Shore. This makes the lake unsafe for swimming and can endanger the drinking water supply, not to mention the environmental implications of raw sewage flowing into the water.
Lakeshore property (like Northwestern's Evanston campus) can also be endangered by flooding.
“People who have property right on the edge do worry about storm damage,” said Neal Blair, a professor of civil and environmental engineering and earth and planetary sciences at Northwestern University. Blair said that he just got a proposal from a local coastline owner who wants to install an underwater rock barrier to protect their property from erosion.
Michigan City, Indiana has found a low-maintenance solution that Brown says can be replicated throughout the country. In a form of green infrastructure streetscaping, they’re creating shallow hollows full of native plants beside the streets. Rainwater falling on the streets is diverted into the hollows, where it’s absorbed into the ground and helps replenish underground aquifers.
“It just makes a lot more sense to allow nature to do what it does anyway: take that water into itself, take it out of these systems, and reduce the overall water that we need to manage,” Brown said.
As if intense storms and increased flooding weren’t enough, Brown said that lake levels will fluctuate more and more dramatically in the future. High variability of water levels can jeopardize infrastructure meant to manage erosion or drinking water intake. This, too, can be difficult for municipalities to manage.
Increasing erosion is another concern. Structures normally under the sand or in the lake can be exposed and pose a threat to public health. Central Beach in Indiana, for example, had to be closed for public use last year after a storm created waves that completely eroded the beach and exposed concrete infrastructure that made the beach unsafe.
An article published in the Chicago Tribune in August detailed the erosion of the lake bed since development in the early 1800s displaced large quantities of sand. Since then, waves have been wearing away at the clay soil of the lake bed, deepening the water. As the lake gets deeper, the waves get higher and stronger, which in turn accelerates the erosion.
According to Brown, erosion and movement of sand is natural, but when the clay soil under the sand erodes, it’s irreversible and irreplaceable.
“That’s when you start seeing this really detrimental feedback loop because that deepens the water closer to the shoreline… then you get those higher waves,” Brown said. The increasingly powerful waves that result can make beaches and piers unsafe and swallow them up over time. As the waves eat away at the shoreline, valuable lakeshore property and public spaces are threatened.
Brown said that the Alliance is working with key stakeholders throughout the region to find a long-term solution to the erosion of clay soil.
Philip Willink, however, isn’t very concerned. A senior research biologist at the Shedd Aquarium, Willink says that lake levels are probably going to drop over the next few years, exposing more land and reducing the presence of large waves.
“What we’re looking at in regards to lake levels is a new equilibrium,” he said. “And we don’t know exactly where that’s going to be.”
Lowering lake levels could make harbors too shallow for boats and ships to leave, causing issues for freighters and shipments of goods and costing millions of dollars in harbor dredging, according to Willink. A shallower lake would also dry out shallow water intake pipes or cause them to take in sand, forcing municipalities like Evanston to make deeper pipes or find new sources of water intake.
Still, Willink isn’t concerned about finding solutions to these issues.
“We manipulate the environment so much,” he said. “When the beaches get too small we just bring in truckloads of sand and make the beaches bigger again… We’re not letting nature run its course. We’re changing things all the time.”
In regards to the erosion of clay soil, Brown once again emphasized the importance of native vegetation.
“When it comes to reducing erosion in general, plants are our best friends, especially native plants with their strong root systems,” Brown said. “Nonnative plants often have very flimsy root systems and they don’t do a good job of holding the land together to reduce erosion.”
The Alliance for the Great Lakes advocates for living shorelines, “but we understand that there are a lot of landowners who have different ideas about the shoreline,” Brown said. “And we don’t own their land. They’re the ones who own their land.”