The Mississippi River is healthier than its been in years; the fish we like are back and the bald eagle population is booming. But invasive Asian carp, sediment and pollution still pose challenges to the long-term health of the river.
That glass-half-full-glass-half-empty situation was detailed in a new "State of the River" report issued Thursday by the National Park Service and Friends of the Mississippi River.
It used existing data and the work of 30 scientists to create an overview of the river.
MANY SPECIES DOING WELL
The health of the Mississippi River today, compared to 40 years ago, is good.
Before wastewater treatment plants and pollution limits, game fish like walleye and smallmouth bass had practically disappeared from the section of the Mississippi that runs through the metropolitan area.
Now, the fish are back. Mussels are also back — they are an important sign of good water quality. And bald eagles, which depend on fish, are back too.
Lark Weller is water quality coordinator for the National Park Service, which manages the Mississippi National River and Recreation Area. She said the metro stretch of the river has 36 nesting pairs of bald eagles, and they're raising healthy families.
"The basic threshold that we call a healthy reproducing population is when there's one eaglet, one baby eagle per nest; our nests in the park average about two per nest, so we have a really healthy population," Weller said.
The National Park Service has been monitoring contaminant levels in the eaglets' blood over time and found that many of those are going down as well, Weller said.
Another positive sign: Over the last 10 years, the Metropolitan Wastewater Treatment Plant has reduced the amount of phosphorus it pumps into the river by 90 percent.
THREATS: SOME FAMILIAR, SOME NEW
But the report also highlights several important concerns, most dramatically the threat posed by invasive Asian carp. Minneapolis Mayor R.T. Rybak said he wants Congress to direct the U.S. Army Corps of Engineers to close the lock at the Upper St. Anthony Falls to halt the spread of the carp.
"We make one mistake and it's over," Rybak said. "We should not be waiting to discover Asian carp upriver."
There are other new threats to the river's health. The report urges people to avoid using products that contain the antimicrobial agent triclosan. Wastewater treatment plants are not designed to remove products like triclosan, said Bill Arnold, a professor in the University of Minnesota's Department of Civil Engineering.
Triclosan is found in a wide variety of household products like soaps, toothpastes and deodorants. Chlorination used to clean waste water can cause the triclosans to morph into something called dioxins. Dioxins are highly toxic compounds.
"A recent USGS study has found triclosan throughout Minnesota in sediments downstream of wastewater treatment plants," he said. "My own group's work has looked at Lake Pepin and we've found that over time the levels of triclosan in Lake Pepin sediments have been increasing and the dioxins that are derived from triclosan have also been increasing."
One of the biggest threats to the upper Mississippi comes from a major tributary. Three-quarters of the sediment in the Mississippi comes from the Minnesota River — and sediment is filling in Lake Pepin at 10 times its natural rate.
"Your curb is your lakeshore, it is your riverbank."
The report includes suggestions for policy makers and for those of us who live along the river
Friends of the Mississippi River's Watershed Program Director Trevor Russell said there are things we can all do to protect the river.
"Pick up after your pet; it's a major source of phosphorus and bacteria pollution to the river," Russell said. "Rake up your leaves. Use lawn chemicals wisely. Everything that's on your lawn is eventually going to flow into street, and your street is waterfront property. Once it's in the street it's in the storm drain; once it's in the storm drain it's in the river. So your curb is your lakeshore, it is your riverbank."
Russell said because it's in our backyard, we tend to forget what a majestic, special place is the Mississippi. He and the other authors are hoping the State of the River Report will remind us to treasure and protect it.
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