A bridge replacement backlog is looming in Boone County.
"We're going to have a peak coming up here of structures that are going to need a lot of reconstruction and a lot of maintenance," Boone County Highway Engineer Justin Krohn said.
One of those bridges is the Poplar Grove bridge near General Mills. The county say it's going to cost around $4 million to replace. Three million in federal dollars and about a million on the local level.
"It's something every county and every community struggles with is how to pay for that infrastructure, because as we go on, it becomes more and more expensive," Boone County Board Chairman Karl Johnson.
"We are prepared for this bridge, but we have at least 16 other bridges coming up that are going to need help on the local level," Krohn said.
That's because most of these bridges have one thing in common, they're past their 50-year design life.
"A lot of our structures in our county and the adjacent counties were built in the 50s and 60s," Krohn said.
Now, county engineers say they're in a tough spot to try and replace and repair these aging bridges over the next 20 years.
"The county and townships are in a very difficult situation and the funding doesn't seem to trickle down as it used to," Krohn said.
And with money tight, the county says it's looking more to federal and state grants like the one it's using to pay for the Poplar Grove Bridge project.
"We'll need to continue that, otherwise it's just not feasible to do it on our own," Krohn said.
An expensive undertaking, but one engineers say is important to keeping drivers safe across Boone County.
Highway engineers expect construction on the Poplar Grove bridge to start in the next two years.