Nahant Marsh recently acquired a 60-acre parcel, seen at center/right in this photo (an open field).
In its nearly quarter-century of existence, Nahant Marsh in southwest Davenport has worked to grow and improve inside and outside its borders.
The nonprofit organization and education center (located at 4220 Wapello Avenue) is nearing completion on a major stream restoration, enhancing wetlands and growing 2,500 new trees.
Executive director Brian Ritter says that the re-routing of Walnut Creek has been in the works for more than seven years as part of Nahant’s long-term restoration plan. There are a series of drainage ditches that drain the whole area, coming directly into the marsh.
Nahant started in 2000 as 78 acres and had no ability to protect the greater wetland complex. “We knew we had to acquire more of this to slow down that water, but also have better impact for wildlife,” Ritter says. “It really has been a process that started when we began as an organization 24 years ago, acquiring these parcels and gradually figuring out creative ways of doing the restoration.”
Nahant is currently at 382 acres, with the organization behind it actively pursuing other parcels. They just finished paying off a 60-acre property on the north end of the marsh, negotiations for which had been ongoing for about 20 years.
“We could never come to a consensus on price,” Ritter says, “and what finally pushed it over was the (River Bend) food bank, which is on the other side, needing to expand. They said, ‘We’ll buy 10 acres and you guys buy the 60 acres.' That was a really great partnership.”
Another partner was the Iowa Natural Heritage Foundation, which bought the land on Nahant’s behalf and repaid the foundation at a below-market interest rate. Ritter says that part of the restoration was to plant new trees and re-do land they are in, so it’s not so flat. Dead trees there were wiped out by emerald ash borer from the 2019 Mississippi River flood.
“We decided we were going to turn this into a wetland mitigation bank,” he says. Nahant Marsh sells wetland credits to companies or organizations that destroy wetlands, which requires them to replace wetlands, according to federal law.
“A lot of places don’t want to build their own wetland,” Ritter says, “so they buy credits from a certified wetland bank, and that’s what we are.” Nahant started the reforestation and sells credits to pay for it. The city of Davenport is one such recipient, and the Iowa Department of Transportation also bought credits for altering wetlands for a bridge construction.
The land had a low-diversity forest, formerly of green ash and silver maple trees. Nahant created 30 shallow depressions and ridges, so the land undulates.
In 2021-22, 2,500 trees – a mix of oaks, pecans, hickories, and sycamores – were planted. If there’s another similar flood, most of them will survive, Ritter says. After 20 to 30 years, they will produce fruits and nuts for wildlife. A lot of timber, meanwhile, was sold to help pay for the new trees.
“Once these trees are mature, they can capture moisture out of the ground,” Ritter says, noting it will help dry the land out, cleaning the water in the process. “It's very flood-prone here.”
The Nahant Marsh team wanted to do a better job of filtering the water. About 10 percent of the time, the Mississippi River floods the marsh, so they focus on the 90 percent where water is flowing off the surrounding landscape. To help improve, they build more wetlands to absorb water from the river.
Construction on the re-routed stream was completed in mid-October. Walnut Creek used to run into this area, and around 1930, the upper half was straightened and the lower half was channelized into a drainage ditch. The issue with ditches is that there are habitats affected by runs that move water quickly, and any contaminants are rushing into the marsh, not getting filtered.
The Nahant team took a quarter-mile drainage ditch and created a much longer, meandering stream, forcing water to move more slowly. There will consequently be more prairie plants added, helping to capture the pollutants.
“Essentially, this is a way for us to protect the main marsh,” Ritter says, “to capture a lot of that pollution and, in the process, create some awesome new habitat for wildlife.”
The ripples, he explains, help introduce oxygen in the water, a source for beneficial bacteria that captures the pollutants. It's anticipated that beavers will also create dams, further slowing water down, letting sediment settle, and cleaning the water.
When the creek floods, there is a mini floodplain for it to spread out, Ritter says. “It’s not a raging river, it’s gonna be a small creek, except when we get a big rain event. That area will be planted with native prairie grasses and wildflowers.
“This will be beautiful. If you come back in a year or two, it will be full of wildflowers.”
All the soil excavated for the creek is piled along the 60-acre parcel on the north side, where there’s an eagle’s nest nearby. Ritter says the property had been farmed intermittently (and unsuccessfully) for years. The vast majority of the land will be turned into wetlands with prairie around it, also helping slow the pollution. The wetland restoration may begin by fall of 2025.
Nahant March has been taking water samples for 15 years, and the biggest pollutants coming into the marsh are chloride (from salt), phosphate (from fertilizer), and soil runoff, creating unnatural silt.
“We think we can capture those three main pollutants, and keep them from getting into the main marsh, and ultimately the Mississippi River,” Ritter says. “Slowing the water down, allowing the plants, the bacteria, even mussels that will eventually be in the stream to capture that pollution. We think our water quality will be much improved by these projects.”
The stream construction, forest restoration and prior wetland restoration (39 acres bought in 2019) cost $700,000, and Nahant partnered with a company (EA Restoration, in Johnson County) to fund the stream. EA Restoration will get 88 percent of stream mitigation credit sales. Most of Nahant's funding comes from grants, private donations, and partnerships. This year, half of Nahant’s $1-million budget was covered by sale of wetland credits.
Ritter became Nahant’s first employee in 2007. Now, there are 12 year-round staff members, and this past summer, Nahant had 14 seasonal workers – 11 doing research through a partnership with the National Science Foundation.
“It’s been incredible to see it grow,” Ritter says. “We have an awesome staff that really cares about this place.”
For more information, visit NahantMarsh.org.
