About a month ago, a frack-sand mining operation near Grantsburg, WI, spilled some fine-grained sediment from a settling pond into a tributary of the St. Croix River. Local news media covered the story, and more details, for example, can be found in the Pioneer Press story by Dennis Lien.
So what’s the big deal?
Well, there are standards regarding water turbidity, which means that as a society we’ve decided that we don’t like cloudy water, at least in some settings and at some levels. For a naturally clear-water system like the St. Croix, increasing turbidity would alter the food chain at all levels. Algal primary producers rely on sunlight blocked by turbidity. Sight-based predation at the top of the food change would be altered. Benthic (bottom-dwelling) organisms that depend on coarse substrates could be smothered by siltation. Especially in the St. Croix, one of the last refugia for freshwater endangered mussel species, we must be on guard against too much fine sediment. And finally, where does the sediment end up? It’s filling up not only man-made reservoirs but also treasured natural lakes, iconically Lake St. Croix and Lake Pepin. These lakes are filling in with fine-grained sediment at about 3X and 10X their natural rates, respectively. (How do we know? See work done by the Museum’s St. Croix Watershed Research Station.)
Hey, it’s only a little bit...
Or was it? How much is a little? A little here, a little there, and a little more from over there -- it starts to add up. All water in a watershed runs downhill to the river, efficiently carrying both particles and dissolved materials. The river ultimately sees it all: all the disturbances, however seemingly minor, throughout the watershed. Rivers die a death of a thousand cuts. We have enough difficulty trying to control nonpoint sources of sediment and other pollutants. Stopping discharge of fine-grained materials from a mining operation is eminently fixable. It’s the right thing to do. Fortunately, all parties seem in agreement on this, including the mining company, which has repaired its leaky dike.
The Mississippi River at downtown St. Paul crested this morning around 10:00 at 19.1 feet, making this year's flood the 8th highest flood of record. So far.
Courtesy City of St. Paul
You see, we're not out of the woods yet. There's a good possibility that we may see a second crest, and the extent of that flooding will be determined by how quickly temperatures warm up (and stay warm) and whether or not we get any big rainstorms.
The Advanced Hydrological Prediction Service has released a new short-term forecast for the Mississippi River at downtown St. Paul. (There's still too much uncertainty in the models to make a new crest prediction for the area.) We should see the river rise above flood stage by midday on Thursday, 3/24.
Courtesy National Weather Service
Click on the image for a larger view.
Yesterday, Mayor Coleman declared a "state of local emergency." The declaration clears the way for the City to start tracking flood-related expenses, in the hopes of getting some of them reimbursed. And there will be lots of expenses this year. There's a 50% chance of a record crest (beating the high water mark of 26.4' in 1965), and a 70% of a crest above 17'. Workers at the downtown airport began installing the flood wall yesterday, and residents of Lowertown and the Upper Landing are being asked to have a plan in case they're evacuated. The lower portion of Lilydale Regional Park, parts of Harriet Island, and the low-lying areas of Shepard/Warner Road will likely be submerged.
With several days of above-freezing temperatures and some rain in the forecast, the National Weather Service expects we could start to see flooding in downtown St. Paul by the weekend.
During the 1960s an average of 5 dams per day were built in the U.S. Many of those were licensed for thirty or fifty years of operation. So, as we approach the close of 2010, a lot of our dams are itchin’ to come down.
As you may imagine, removing a 95-year-old, 210-foot tall dam is no easy feat.
Enter Dr. Gordon Grant, research hydrologist with the USDA Forest Service and professor at Oregon State University. Gordon has worked on some of the largest dam removals in the history of the U.S. Tonight he is all set to tell us about such endeavors. Gordon will be speaking at Research at the Red Stag at 5:30pm. His talk is entitled “Out, out damn’d dam: freeing wild rivers.” It will certainly be a highlight of my November.
Alright, it's absolutely beautiful outside today. So what's up with this predicted flooding?
Remember all that rain the week of September 20th? (We got 2-4" here in the Twin Cities, but areas to the southwest of us got as much as 10".)
Courtesy National Weather Service
It all had to go somewhere, and that somewhere was the Minnesota River. Why does that affect us here in St. Paul? Take a look at another map:
Courtesy NASA (Landsat)
Remember: rivers don't necessarily flow south. The reddish line is the Minnesota River. The blue is the Mississippi. And that little blip just north of where the two rivers come together is downtown St. Paul. (The yellow elipse is the area of highest rainfall.)
All that rain is flowing right past us. And it should be impressive. The river's at 15.4' this morning (moderate flood stage), and predicted to crest at 18' (major flood stage) on Saturday morning. But the recent spate of lovely weather means that the flooding should pass quickly--today's prediction has the water level back under 17" by Monday morning.
St. Paul police have closed all the river roads and parks, and are discouraging people from walking down by the river. But you can get a stellar view of everything from outside the Museum on Kellogg Plaza, or inside the museum from the Mississippi River Gallery on level 5.
With forty-four percent of our 3.5 million miles of rivers and streams degraded due to sedimentation and excess nutrients, stream restoration has become big business in the United States. Estimates show that over $1 billion has been spent on stream restoration projects in the U.S. in every year since 1990.
Trouble is, the field of stream restoration lacks a lot of scientific rigor, making the prediction of successful restoration strategies difficult. Take, for example, one of the most commonly used tools of the trade—the in-stream structure. Man-made, in-stream structures (think small wall jutting out into the water from a stream bank) are frequently used in stream restoration and management to try to stabilize beds and banks or to improve aquatic habitat. Despite the frequency with which they are used however, engineering standards for the design and installation of the structures are inadequate, a problem that would be good to remedy if we are to make reliable predictions about whether a given stream restoration strategy or project will succeed.
Establishing comprehensive, quantitative engineering guidelines for in-stream structure installation and maintenance is far from simple though. The underlying physical processes that govern the behavior of a stream and its inhabitants are very complex. To deal with the complexity, researchers at the National Center for Earth-surface Dynamics (NCED) have come up with a novel approach—build a near-field scale experimental stream and a computational “virtual” stream to help elucidate the underlying interactions of water, sediment, and biota.
The experimental stream is the Outdoor Stream Lab (OSL) that sits right on the Mississippi River. The virtual stream is the (surprise, surprise) “Virtual StreamLab” (VSL) that exits as code within massively parallel supercomputers. This past summer, NCED researchers were able to complete their first simulation of a real stream (the OSL) using the VSL (see the video above). The simulation involved mapping more than 90 million data points into the computer model. The result was the most accurate model of a real stream to date.
The ability to simulate water flow over topography with this degree of realism will provide researchers with the insights necessary to improve sustainable stream restoration strategies and help to optimize techniques to fight erosion, prevent flooding, and restore aquatic habitats. NCED researchers are currently using their simulation to develop comprehensive, quantitative design, installation, and maintenance standards for in-stream structures.
With so many miles of degraded streams and rivers in the United States, the VSL is a good step in the right direction for the design and use of in-stream structures specifically, and for the field of stream restoration generally.
Mississippi River peaks Wed. March 24, 2010 at Harriet Island Saint Paul, MN.
For hundreds of years, thousands of people have connected with the Mississippi River. Today, we sometimes forget that the Mississippi is always flowing through our fair cities, at least until it floods.
In this moment, the river can be an extraordinarily humanizing resource. When we stand together on the Science Museum's plaza, peek over the rails on Kellogg Blvd.'s parkland, or sit near the steps on Harriet Island, all gazing at the flooding river, we are not accountants, scientists, or novelists but everyday people witnessing an event that still produces the same awe, fear, romance, or dread that thousands of people for hundreds of years before us have experienced when they too watched or experienced a flood.
In future posts, my colleagues and I will chat about the impact of flooding on the Mississippi's landscape and try providing some historical perspectives on river floods.
If you'd like to learn more about our National Park Service unit, the Mississippi National River and Recreation Area, please visit us at www.nps.gov/miss.
Check out our full feature on the 2010 Mississippi River flooding.
That's 2 feet higher than predicted yesterday, and would make the 2010 flood #7 on the top-ten list of recorded floods at this site.
Check out our full feature on the 2010 Mississippi River flooding.