ST. PAUL, Minn. – The U.S. Army Corps of Engineers, St. Paul District, is temporarily closing Lock and Dam 7, in La Crescent, Minnesota, July 22, 24, 29 and 31, to replace all four main lock chamber miter gates. The lock will be closed to all commercial and recreational river traffic, from 7 a.m. to 7 p.m. on these days.