Weiss: Some good, some not-so-good for Mississippi River
Environmental Management Program report card has some good news, some disheartening news for lovers of the upper Mississippi River.
Lovers of the Upper Mississippi River in this region, take heart:
- Common carp numbers are dropping, while the river is still blessedly devoid of the Asian carp that are violating it farther south.
- Water up here is much clearer than 25 years ago and plant life is again thriving after a crash about 40 years ago.
- Game fish, such as largemouth bass, sunfish and yellow perch, are increasing thanks to the cleaner water and more plants.
- Phosphorus levels are down, which means less algae because phosphorus is a critical chemical for them in freshwater.
Now, disheartening news:
- Sedimentation continues its insidious, relentless filling in. Tens of millions of cubic yards of sand and dirt from the river’s massive watershed have been threatening the backwaters ever since they were created in the 1930s.
- Nitrate levels haven’t changed, which is really bad news for the Gulf of Mexico’s Dead Zone - nitrates are the critical chemical for algae in salt water.
- While nutrients are down or the same, the Mississippi river continues to have way too many nutrients to meet federal water standards.
- Annual flows are increasing, which can mean more trouble for boaters and sandbar campers. And duration of floods has a big impact on plants.
Those are among the observations in a new report called “Ecological Status and Trends of the Upper Mississippi and Illinois Rivers.” It is 200 pages of documents and graphs covering the Mississippi from south of the Twin Cities near to St. Louis as well as the Illinois River. It is the result of the federal 1986 Water Resources Development Act that created the Environmental Management Program. The EMP is taking a closer look at the Upper Mississippi because it’s so valuable but is also facing significant ecological threats, mainly due to the lock-and-dam system.
Teams of experts have been probing, investigating, measuring and monitoring several stretches of the river for more than a quarter century. The two sections around here are Pool 4 from the lock and dam above Red Wing through Lake Pepin and down to Alma, Wis., and Pool 8 from Genoa, Wis., Lock and Dam to the Dresbach Lock and Dam upriver of La Crosse, Wis.
The report is their first major report card. “The scope, scale, duration, and scientific rigor of the LTRM are unique among large rivers in the United States and perhaps even the world,” according to the report.
The Mississippi is an amazingly complex ecosystem so any report on how it’s changed in the past 26 years would also, out of necessity, be complex. There are many places where the experts said basically: this is what we found, but we’re not sure why it’s happening. Maybe that’s because what’s happening on the river reflects what’s happening in watershed and all its myriad tributaries and that is complicated. John Muir hinted at that when he wrote: ”When we try to pick out anything by itself, we find it hitched to everything else in the Universe.”
I’ve fished, canoed, hunted, watched wildlife and enjoyed the Mississippi those 26 years and nearly two decades more. Reading the report was, at times, like reading my past. I didn’t find any ah-ha! insights or news that stunned me. But it was welcoming to see so many things documented because here’s one of the best things about this report - it’s a blueprint for where we can go from here. It offers those who manage the river things to think about and maybe change or preserve.
Before we go on to more details, a quick history lesson:
For eons, the Mississippi flowed freely, filling in or opening new channels, creating and always renewing its habitat for fish, plants, migrating waterfowl and later for native Americans. When Europeans came, however, the river didn’t suit them because it would get too low in summer so in the late 19th century, a program began to build wing dams to force the river to dredge itself. That didn’t work, so in the 1930s, the locks-and-dams system was built from south of the Twin Cities to north of St. Louis. With that, the river became a series of pools and the main channel is always at least nine feet deep. That also created the backwaters behind the dams and they soon blossomed into incredible places for waterfowl, plants, hunters and anglers. But the Mississippi could no longer drop low enough in summer for new plants to grow nor could it open new channels. Slowly, the backwaters are filling in, they are getting old and can do little rejuvenation.
For reasons not well understood, backwater vegetation dramatically crashed in the late 1980s and some feared the river ecosystem was on the verge of collapse. But it’s coming back and to help it, there have been small drawdowns to expose more soils to sunlight, and get more vegetation, as well as island building to slow the wind from roiling and muddying the water.
That’s where we are now.
Here are some other findings from the report that, to me, seem important, as keys to understanding what’s happening. (I’m concentrating on the river in our region because the lower Mississippi reaches and Illinois River are so different):
- Floodplain forests are dwindling and changing with the additional high water that can kill certain trees, as well as with more invasive bugs like emerald ash borer. Once trees are gone, that wretched reed canary grass and other invasive can take over and choke out any chance of more forest.
- The amount of dissolved oxygen, super critical for any fish to survive, is decreasing in winter in backwaters of Pool 4; low DO was more widespread up here than farther south. Conditions were worse from 2005-2010 with unusually low flows.
- While a little reduction has been made in amounts of agricultural fertilizers in the watershed, it’s not nearly enough to help the river. And “large amounts of legacy nutrients remain on the landscape,” it states. “Groundwater in the region is rich in nitrate as a result of years of fertilized agriculture and analyses indicate it will take decades before nitrate is sufficiently reduced even if fertilization stopped now.” Experts predict more heavy and more frequent downpours “which can increase nutrient and sediment delivery to the river.”
- More dry land is slowly being added to the ecosystem as sediment fills in enough to push land above the water. Most of that dry land came in the Upper Mississippi. Besides less aquatic habitat, that can also mean less water, along with dissolved oxygen, flowing into backwaters.
- The amount of forage fish, such as shad and emerald shiners, is dropping in Pool 4 out stay in Pool 8.
Overall the fishery “represents perhaps the most intact and functionally sound fish community in a large, developed, and modified temperate river anywhere,” the report states. But adds a warning - they have only been looking at 30 years but humans began modifying the river 150 years ago.
John Weiss has written and reported about Outdoors topics for the Post Bulletin for more than 45 years. He is the author of the book "Backroads: The Best of the Best by Post-Bulletin Columnist John Weiss”