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U.S. Army Corps of Engineers
St. Paul District
Programs & Project Management
180 5th St. E., Suite 700
St. Paul MN 55101

(651) 290-5755.


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Posted 2/26/2015

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Updated September 2018


Lock and Dam 1 is located on the Minneapolis side of the Mississippi River.  The purpose of this project is to re-establish armor downstream of the concrete apron.   The existing rock protection consists of grouted derrick stone.  This stone bedding has broken up and washed downstream, exposing bedding material and risking failure of the wooden piles and sheet pile located underneath the existing concrete apron.



The U.S. Army Corps of Engineers performed a cursory analysis in fiscal year 2013 and determined placing riprap 200 feet from the concrete apron downstream would be the most efficient and effective solution. Construction involves a contractor removing grouted riprap, excavating excess material immediately downstream of the concrete apron, and using the material to smooth out the downstream topography.

The Corps completed plans and specifications fiscal year 2015 and awarded a construction contract in September 2015. Unfortunately, construction was adjusted nearly three years due to continued high water. Persistent high water has prevented the contractor from accessing the area safely.

The Corps will conduct site surveys of the area in late summer/early fall when water levels have lowered enough to allow safe access. Pending the results of the site surveys, the Corps will assess the current design, update plans and specifications, and award the construction contract in fiscal year 2019.


The project was authorized as part of the River and Harbor Act approved July 3, 1930.


Project design and construction costs are 100 percent federal.

Project costs to date                            $441,692

Estimated contract cost                     $2,500,000

Ambursen Dam Downstream Repair dam safety Lock and Dam 1 Mississippi River St. Paul District U.S. Army Corps of Engineers