Moreau Bank Stabilization

Lake Oahe, South Dakota


This project was located in Dewey County, South Dakota on the river bank at the junction of the Missouri and Moreau Rivers.  The goal of this project was to stabilize the river bank and protect a Historic Native American Village site.  Access to the work site was obtained through cooperation with the reservation and a private landowner.

Two miles of the existing access road/driveway leading to the ranch house was improved so it could be used as a haul route.  A stock pile area was established near the house and top soil was stripped in preparation of transferring the riprap from side dump tractor trailers to tandem dump trucks.  The nearest source for the required 4,000 lb riprap was located 220 miles from the job site.  The riprap was delivered to the site using semi trucks, most pulling two side dump trailers to minimize transportation costs.  It was dumped at the stock pile area where we then loaded it into tandem axel dump trucks and hauled another three miles through the pastures on a “two-track” path.  This was required due to the hilly terrain and the length of the tractor trailers.

At the river bank we built, shaped and compacted the base for the embankment which was approximately 1,200 ft long and averaged 40 ft wide.  Tie-backs reaching approximately 50 ft into the side hill were installed on each end.  Construction of a haul road around the point was required to allow equipment access to the work area.  We installed geotextile stabilizing fabric over the base and placed 10,000 tons of riprap along the river bank.

We installed three cattle guards at locations where existing fences/gates crossed the road leading to the ranch to facilitate the delivery of riprap without concern of disturbing the ranch operations.

Contract Details


  • Value: 785,125.00

  • Project Manager: Mark Lannon

  • Affiliate: USACE Oahe Dam