Flooding on Belle Isle has resumed. What does that...

Flooding on Belle Isle has resumed. What does that mean for 2020 and beyond?

Belle Isle flooded

Photo: East end of Belle Isle, April 5, 2020. Photo by Amy Sacka

In retrospect, April of 2019 may not have been the best time to reconnect Belle Isle’s Lake Okonoka and its adjoining canals with the Blue Heron Lagoon and the Detroit River.  The project, originally designed to create natural habitat on the island’s eastern end, also opened a path for the historically high Detroit River to flood the interior of the island. The floodwaters have shut down the ring road that circles the park, inundated part of the ecologically significant hardwood forest, closed down picnic shelters, and delayed work on the Piet Oudolf garden near the Nancy Brown Peace Carillon for the past year. 

Of course, project planners didn’t think the water would come up so high, especially being not so long after 2013’s record low. Great Lakes water levels in 2019 and in 2020 have broken records.

“When we were designing this we were more worried [about] what would happen if [Great Lakes water levels] go low,” Sam Lovall,  a project manager for the Friends of the Detroit River (FDR) who is overseeing the Lake Okonoka Habitat Restoration, told Planet Detroit. The decision to launch the project was “based on data,” he said, “and all we know is that [with] previous data, we’ve never seen water levels in the Great Lakes like this.”

The FDR hoped the project could be a win for both park visitors and wildlife, creating acres of diverse bird habitat, fish spawning grounds, and water trails that would allow paddlers to move nearly from one end of Belle Isle to the other through lakes and canals.  Funded primarily by the National Oceanic and Atmospheric Administration (NOAA) through the Great Lakes Restoration initiative, construction on the project began in 2017 at a cost of more than $5 million.

Instead, much of the island has been rendered inaccessible due to flooding.  For those wanting to reconnect with the relatively wild eastern end of Belle Isle, it’s worth asking when they might get some of their park back, and what the past few years may have taught us.

“I think the biggest lesson learned is that to go from all-time lows to all-time highs in under a decade… kind of shows that we need to think about shoreline engineering very differently.” Donald Carpenter, a professor of civil engineering at Lawrence Technological University, told Planet Detroit. Accounting for these wild fluctuations will mean building “adaptability and resiliency” into future projects, he added. 

Several projects underway on Belle Isle are beginning to implement measures that can cope with a range of water levels. A 400-foot-long, ten-foot-high temporary cofferdam–which cost $95,000– is being installed where the Blue Heron Lagoon connects with Lake Okonoka. These structures are normally used to create a dry area for working on things like bridge pilings but it’s being employed here because it is removable, separating the canal system from the river so that water can be pumped out. 

But the cofferdam requires that the pumps in the island’s canals–which Ron Olson, Chief of Parks and Recreation for the Department of Natural Resources (DNR) says may have been over 30 years old–needed to be repaired in order to move water off the island. The $26,030 cost for repairing one pump was paid for by the Belle Isle Grand Prix, while another still needs to be fixed at an estimated cost of $5540.

“We’re hoping that the water balances itself out so that we don’t have the water creeping up and flooding areas that were flooded like last summer,” Olson said.

A culvert at the outlet of Lake Okonoka to allow water and fish to pass into the Detroit River has not yet been punched through due to high water. Once the waters go down, it can be completed. If high water comes back in future years, the culvert could be closed off again and the cofferdam put back in place, potentially affording the DNR the tools they need to adapt to changing water levels. 

Three other projects are underway that could help manage water levels on the island. 

A plan to reengineer Central Avenue – which cuts through the island’s currently waterlogged and inherently soggy flat woods â€“ will restore the hydrology that helps balance moisture levels across the island.  Also, the DNR will permanently close Oakway Road and replace it with a trail and native vegetation to help with water management and create more space for recreation. Finally, Woodside Drive on the north shore of Lake Okonoka will be closed in part, making room for a 200-foot swale or depression that connects the lake with the woods, and would further buffer against flooding by encouraging water to move into the soil.

Controlling flooding on Belle Isle with localized measures like cofferdams and swales, however, can only go so far. A massive amount of water moves through the Detroit River system, with about 1.3 million gallons discharged every second. 

“The volume of water is so great that you need some hard elements,” John Hartig of the Great Lakes Institute for Environmental Research at the University of Windsor told Planet Detroit

Belle Isle, April 5, 2020. Photo by Amy Sacka

Hartig agrees with Carpenter, noting that in the long term, managers will need to make coastal wetland systems like those on Belle Isle more adaptable to an uncertain future. With waters forecasted to rise above historic highs into June, this season could well tell us if the current strategies of using temporary dams and pumps will work.

Angela Lugo-Thomas, a park advocate with the group Belle Isle Concern that was formed to oppose the presence of the Detroit Belle Isle Grand Prix car race on the island, said she wishes the Michigan DNR and FDR had been more forthcoming about what may have gone wrong with the project. And she remains skeptical of plans to manage water on the island going forward. “It all depends on how the next few years go,” she says. However, she supports the idea of opening up the park to more wildlife and connecting the lakes and canals with the river. 

“We might find that maybe some of the parts of Belle Isle are just returned to nature,” Lugo-Thomas said. “And we’ll just have to adjust to that.”

This year could still continue to surprise park users and administrators. Lovall said that water continues to come in from basically everywhere in the park and that the island’s high water table means it often doesn’t have anywhere to go. Last year, boat wake pushed water from the main channel of the Detroit River into at least one picnic shelter, something that could get even worse if water-level records continue to be broken. 

“If we get much higher water in the Detroit River,” he said, “it wouldn’t matter if we did this project or not.”

Brian Allnutt is a writer living in Detroit. He covers open space, environmental justice, food and gardening.