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RIVER LIFE

St. Anthony Lock to Close: Now What?

On Tuesday, President Obama signed the Water Resources Reform and Development Act (WRRDA) into law.  Mark Gorman at the Northeast-Midwest Institute has posted a summary from one of the national environmental news services.  WRRDA sets federal policies on inland waterways such as the Mississippi River and its tributaries for a number of years; this is a big deal.

Close to home, a section of the Act stipulates that Upper St. Anthony Lock will be closed on or before June 10, 2015; statutory language is “a year from enactment of the law.” This is also a big deal.  The decision is being widely touted as the most important action that can be taken to stop the spread of invasive carp into the lakes region of Minnesota.

Maybe so, but clearly efforts to stop the invasive fish farther downstream must continue.  We can’t simply let the carp get all the way to Pool 2, in St. Paul, and then say “that’s far enough.”  It remains to be seen, though, how urgent the carp are as a priority now that the lock will be closed.

Other things remain to be seen as well.  To my knowledge, this is one of only a very few times that a lock has been ordered closed on a navigable river.  The circumstance gives us an unparalleled opportunity to study how the Mississippi River works and to develop future river management approaches based on scientific investigations.  For example:

  • The Corps of Engineers has indicated that dredging for channel maintenance will stop above Pool 2 (the Ford Lock and Dam).  Will lack of dredging mean that sediment will fill in the riverbed?  Probably not, but if sediment isn’t dredged out, how will the river array it across the bed?  What will be the impacts for fish habitat on the riverbed if there is a lot more sand and silt and less rock?
  • With the end of commercial navigation and large tow boats and barges on this stretch of the river, what will be impacts on streambank erosion?
  • If the lock opens only occasionally for emergencies, or not at all, what might be the impacts on fish migration?  There are currently more diverse populations of mussels above the falls than there were before the lock opened in the 1960s, because the ability of fish to bypass the falls has meant that larval mussels transported by those fish could likewise move upstream.  What are the impacts of that upstream movement being stopped?

These are just three of the numerous questions that scientific investigation of the river system at the point of lock closure can answer.  Closing the lock represents a major change in the management of the river, with associated alterations of the river’s hydrological and ecological patterns that are unknown.  Prudent management of the Mississippi in the Twin Cities would suggest that a program of research be undertaken immediately in order to establish baseline conditions at the point of lock closure and develop indicators of key trends and patterns that can be monitored further.

The impetus to close the lock was the threat of invasive carp.  But the carp are just four species among hundreds found in this stretch of the Mississippi.  Closing the lock is not itself enough to restore the river’s health, but it’s an important step.  Now we need to do systematic science to understand what additional steps will further enhance progress toward a healthy river.

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One Comment

  1. Greg GenzJune 18, 2014 at 11:22 am

    Answers to the questions might be:
    The River will fill with sediment, with a small channel. After the 2012 Duluth super storm, we had 3′ of water in the main channel above Lowry Bridge. I imagine the River will look something like it does around Clearwater, lots of sand bars and shallow water. The real problem will happen downriver, especially in Pool 2. The Corps has dredged an avg of 70,000 cubic yards from the River every year since 1970. This has been sold by the City of Mpls for beneficial use because it is high in desired granular content. Now, once the sediment fills in what it will in Mpls. it will wash into Pool 2 where mixing with the finer sediment of MN River, will make it less marketable. pool 2 is running out of capacity for sediment. Its backwaters and channels are just about full and lack of disposal sites has become problematic. This bodes poorly for the fight to help Lake Pepin.

    Studies confirmed by MNDNR show that towboats and barges cause very little Riverbank erosion. A trip up the MN River, where no towboats go and very little power boat traffic takes place, will show one what the real problem is. Excess water from urban, suburban, exurban, and rural areas utilizing our Rivers as a storm sewer for the State cause the greatest damage to the banks.

    Professor Sorenson is working on studies to utilize native fish passages at locks, once invasive deterrents are in place. Do we have the political will and funding to do what needs to be done? see relentless movement of the Asian carps upriver for the last 20 years for that possible answer.

    I don’t see how one can justify the statement that closing the Lock will improve the health of the River. In my 40+ years on the River, I have seen only one quantifiable action that improved the River. Upgrading the Pigs Eye sewage treatment plant achieved that. Clean up the water entering the Rivers and you will see dramatic improvement. With that in mind, Mpls and the U of M should look at there own houses. The same places that smelled like raw sewage, along the River in the 1970’s, still smell like raw sewage today. No better example of this is right down on the University Flats. Spend a hot summer day down there and tell me closing a Lock will help that!

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