In the early 1900, land development drained the original wetland. Over time, it became a junkyard before park services and volunteers cleaned the land. In 1984, clean up began, hauling away cars, car parts, bedsprings, and all sorts of junk.
Around the same time as the cleanup started, beavers moved back into the area. They had been missing from the area for over a century, trapped out of the area for their fur. The return of the beaver was a sign that the health of the area was returning. They build dams that flooded the area.
With the human cleanup and the beavers flooding the area, dormant seeds reawakened and wetland plants returned, creating a habitat for all sorts of wildlife.
46% of endangered species need wetlands. This marsh coming back too life is an example that it's not to late to reverse the damage.