A couple years ago the city of Devils Lake bought Toulna Coulee and lowered the coulee to 1457', so if the armoured control structure holds back a foot of water, it will still only be at the original elevation.  I just don't see any other way to do it except back up water into Devils Lake (the lake, not the city).  the Sheyenne River is already running at high flood stage and can't take any more.