The Upper Mississippi National Wildlife and Fish Refuge turns 85 this month, and biologists are still hard at work to protect it.
The refuge, stretching 300 miles from Wabasha, Minn. to Rock Island, Illinois, has a storied past. The wetlands have ebbed and flowed from a glorious home for wildlife to a virtual dead zone, and back again.
Established in 1924 by Will Dilg, the park is now the most-visited in the country.
Dilg was an advertising executive from Chicago who fished the river for bass in the 1920s. His son, age 4, fell off the family's houseboat and drowned in the Mississippi. That only made Dilg more attached to the river.
After his son died, Dilg heard that developers wanted to turn the Mississippi's backwaters into agricultural land. He decided to stop that.
Tex Hawkins, a watershed biologist at the U.S. Fish and Wildlife Service, calls Dilg a "marketing genius."
Dilg decided to create the Izaak Walton League as a way to bolster awareness of the environment. He also used it to promote the concept of a Mississippi wildlife refuge.
Hawkins says the effort was wildly successful.
"And by golly, they had chapters in every state. And he could take the numbers to Congress and really lobby for the establishment of the refuge," he says.
But the river of Will Dilg's era was much different from today's.
The river and its wetlands face constant challenges from things like barge traffic and invasive species. Biologists are its stalwart protectors. Hawkins points out a curved arm of rock that cradles an island.
"These are rock groins, and they are there to keep the wave action down and to form little habitat patches, so there will be fish concentrated around each one of these," he explains.
Biologists like Hawkins have had to build most of the islands and rock formations on the refuge. They've also had to study what sorts of formations withstand the waves and high waters, and whether they attract birds and other wildlife.
Eric Nelson, a wildlife biologist who directed this island project, says when the Army Corps of Engineers built the locks and dams for ship traffic in the 1930s, it damaged the refuge. The Corps dredged the slow, meandering river into an inflexible highway.
"Originally when the locks and dams went in in the '30s there were islands. Over time they've eroded due to constant wind and wave action," he says.
When the islands disappeared, so did the food and shelter for wildlife on the river. For decades the wetlands suffered. But they're returning.
"You can see there is cottonwood and willow and some shrubbery growing," he says. "There are a few mallards, a few teal and geese nesting out here right now."
Half a million birds stopped on the Refuge during fall migration last year.
Overall, the river is considered in good health. But parts of it, like Lake Pepin north of Winona, are impaired. Hawkins says pollution is a challenge.
"The river is a reflection of its watershed," he says. "These valleys that you see, these wooded valleys, are bringing cold spring water into the river."
But Hawkins says that's not all these springs have. "Those streams do take a lot of contaminated, polluted and sediment-laden runoff from agricultural and from developed land and that comes into the river as well."
The Minnesota River is a huge source of pollution for the Mississippi. It drains agricultural runoff and sediment into the river. The runoff feeds algae blooms that choke the system from oxygen. Lake Pepin is so polluted with sediment that within 300 years it will be a mud flat.
Invasive species are also harming the river. Hawkins says Asian carp are one example.
"They use the food sources that would otherwise be available to other species. They are planktonic feeders, so they intervene in the food chain. It can impoverish an area from a nutritional standpoint," he says.
They also breed earlier and faster than other fish. Zebra mussels are another known invasive species that threaten the native mussel population, like the Higgins eye pearlymussel. Those two problems are linked. Mussels have fewer fish to carry their eggs upstream. What fish remain have a tough time maneuvering around the locks and dams.
But biologists say they've made a lot of progress, and in the refuge's 85 years there's a lot to be proud of.