Along the Mighty Mississippi, Cities Swap Sandbags for Marshes
Mayor Rick Eberlin of Grafton, Ill., knows that by the end of this week he will probably be in another fight with the Mississippi River.
But sandbags and flood walls are not in his arsenal.
The city of 640 people just below the confluence of the Illinois and Mississippi rivers will allow floodwaters to sweep across its low-lying areas, enveloping roads, parks, docks and a strip of scruffy riverside lots where no one has lived since the Great Flood of 1993.
“We don’t use walls or sandbags. There’s nothing to protect,” Eberlin said Friday afternoon. “What we do is pray that it doesn’t get as high as the forecast. Then we cope with it.”
But don’t mistake Eberlin’s resignation as surrender.
Grafton has been through 18 high-water events since 1993, and Eberlin, a farmer, has learned a few things about negotiating with the Mississippi River. One is to let flood tides go where they want to go.
Eberlin is one of a growing number of Mississippi River mayors who are rethinking what it means to live next to a river whose floods seem less predictable than ever—when spring rains become bomb cyclones and six weeks of gradual winter snowmelt can be compressed into two weeks of sheet-flow flooding across frozen ground.
“What used to be a high-water event every two, three, five years, now it seems we’re getting it every year, sometimes twice a year,” Eberlin said. “I know we’ve got a different weather pattern, and the events are getting more fierce.”
Towns like Grafton have little choice but to take adaptation to the next level.
Rather than simply pulling back from the river’s edge, communities are looking at landscape-scale flood control measures that are also environmentally restorative. Towns are constructing—or rather, allowing nature to reconstruct—marsh and wetland areas that were once the targets of dredges.
When Grafton built a new riverside marina in 2006, it placed tons of dredge material into a river shallow to help establish what is now a functioning wetland that traps sediment; slows water; and provides habit for fish, waterfowl and small mammals.
It also helps reduce flood damage downriver, where communities south of St. Louis have witnessed some of the worst floods on record over the past decade. The events have fueled debate over the role that levees and flood walls have in worsening flood conditions for downstream neighbors (Climatewire, Aug. 8, 2018).
Colin Wellenkamp, executive director of the St. Louis-based Mississippi River Cities and Towns Initiative, said mayors along the entire 2,300-mile length of the river are beginning to see the picture.
“We’re more conscious of these things,” he said. “Our mayors are really beginning to focus on not just managing water in their town, but managing on a corridor scale. It’s not easy and it’s not cheap, but it makes a hell of a lot more sense, and it saves the taxpayer a lot of money.”
‘Doing exactly what it’s supposed to do’
Davenport, Iowa, located a few hundred miles upriver from Grafton, has been an exemplar of landscape-level flood protection.
The city of 102,000 is home to the largest urban wetland on the Upper Mississippi River. Known as the Nahant Marsh, the 305-acre preserve was for decades a hunting and skeet-shooting club. When the club closed in 1995, the marsh was so polluted with spent lead that more waterfowl were dying of toxic exposure than gunshot.
EPA declared the Nahant Marsh a Superfund site in the late 1990s. After the removal and cleaning of about 60,000 cubic yards of toxic soil, the site was handed back to the city. It’s managed today as an education center, providing residents with rare access to seasonally wet bottomland forest, marshland and open water habitat.
But the Nahant Marsh’s greatest community benefit is its ability to act as a massive urban floodwater sponge, catching and filtering up to 2 billion gallons of water during peak flows on the Mississippi.
Brian Ritter, executive director of the nonprofit organization that manages the marsh, said the city of Davenport has long viewed flooding as part of its natural heritage and has adapted accordingly.
Like Grafton, Davenport has no levee or flood wall. Its roughly 9-mile riverfront, including its signature park, is designed to be submerged in floodwaters for weeks at a time.
Former Davenport Mayor Pat Gibbs, who was criticized in the mid-1990s for refusing to build a flood wall along the waterfront, told the Quad-City Times last June that he has no regrets about the decision, even as Davenport’s across-the-river neighbor, Rock Island, Ill., stands by its decision to build one in the 1970s.
“I still believe you give to the Mississippi what belongs to it,” Gibbs told the newspaper. “If the water wants to come in, it’ll come in no matter what you build.”
But as flood frequency and intensity has risen over the last 25 years, the Nahant Marsh has become a community asset in ways few people considered before the Great Flood of 1993.
“We’re flooding right now,” Ritter said last week. “The river went up last week, and the forecast says it will go up again in early April. Our soils are completely saturated, so the marsh is doing exactly what it’s supposed to do.”
Like Eberlin in Grafton, Ritter has kept tabs on high-water events in Davenport over the last two decades. He is convinced climate change is leading to more extreme precipitation and more floods.
“This is our 21st flood that we’re experiencing since the year 2000,” he said. “Historically on this stretch of the river, it was one or two floods per decade.”
“I mean, you know, climate change and land use—it’s the double whammy,” he added. “At one time we had this wonderful prairie sponge all through the Midwest that would soak up the rain and snowmelt. Now we have to build the sponge.”
Even the Army Corps of Engineers, which has invested billions of dollars to line the Mississippi River with levees and flood walls over the last century, has begun to see the benefits of reconnecting the river to its natural floodplain.
In 2017, the Army Corps worked with Iowa, county officials and the Green Island Levee District to buy out privately owned farm tracts along the Maquoketa River, a Mississippi River tributary south of Dubuque, that saw frequent severe flooding.
After high water breeched a 1940s-era levee on the Maquoketa in 2010, the Army Corps opted not to patch the holes but instead offer it to the state as an extension of the 4,000-acre Green Island Wildlife Management Area, one of the state’s most important flood backwaters and wildlife sanctuaries.
Calls to the Army Corps’ Upper Mississippi River Restoration Program, based in Rock Island, were not returned Friday.
Ross Baxter, land projects director for the Iowa Natural Heritage Foundation, said at the time that returning the affected areas to a natural state avoided future infrastructure expenses while better protecting other surrounding farmland from floods.
“Ultimately it made more financial sense to buy, protect and restore the land than fix the levee and continue to farm the flood-prone land,” Baxter said.
Nathan Woiwode, North America climate adaptation project manager for the Nature Conservancy, said the organization has observed a significant uptick in nature-based flood protection measures in the Mississippi River Basin, especially in states like Iowa, Illinois and Missouri.
“These states are taking very intentional looks at how they’ve done floodplain management in the past,” Woiwode said. “It’s not purely about flood protection. It’s also about protecting agricultural interests and creating community assets.”
Woiwode also pointed to the recently launched “Engineering With Nature,” an Army Corps initiative that aims to incorporate natural solutions to water management. The agency in January published an atlas detailing 56 projects that apply nature-based approaches to challenges around river management and flood control.
“It’s about understanding that the things we used to be able to rely upon, like how the water moves through a river system, it’s all changing,” he said. “It’s about recognizing that we need to start planning for a very different future.”
Reprinted from Climatewire with permission from E&E News. E&E provides daily coverage of essential energy and environmental news at www.eenews.net.