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.