OTTUMWA — The dot on the Iowa Department of Transportation’s map looks innocuous enough. Located in northwestern Van Buren County, its light red color designates it as a 2014 project.
The map on the DOT website is interactive, so you get details on the project by clicking the marks. This one says it’s related to wetlands mitigation. Another in the southern part of the county is for a bridge deck replacement. And a line on Highway 34 from Albia to the Wapello County line is for widening the roadway.
Wait a minute. Back up. Wetlands mitigation?
This is the DOT, right, not the Department of Natural Resources?
Scott Marler chuckled just a bit. Yep, he said, wetlands mitigation is a DOT issue as well.
Marler is an environmental resources manager with the DOT’s Office of Location and Environment. But let’s start a little closer to home, with Scott Sommers. He’s a construction engineer in the local division office.
“Whenever we do a project out there in the field and impact a waterway, we have to do a mitigation project,” Sommers said.
Sommers called such projects “very routine.” Marler agreed. There are several issues that come into play when a construction project has an effect on wetlands. The federal government gets a little concerned when people start changing conditions because that can make a big difference for water quality.
Mitigation in many cases means a new wetlands must replace the one changed by the DOT. And size matters. Marler said the ratio is 1.5 new acres for every acre of disturbed wetlands. While there is a loss of habitat in one spot, another area gains.
“No net loss is one of the key terms,” Marler said.
In this case, the project is a new bridge over the Des Moines River near Douds. The new wetland area is in Warren County. It seems odd at first glance that a project in one spot can be mitigated by changes made roughly 100 miles away, but the key idea there is the watershed.