RIVERDALE, N.D. (AP) — A drainage system is being replaced this summer at the Garrison Dam on the Missouri River in North Dakota.

Army Corps of Engineers project manager Todd Lindquist says the system that manages natural seepage at the dam was losing effectiveness.

The project has included drilling a series of wells and pumping water down them to create a dry area for installing drain pipe.

Lindquist says the level of the Lake Sakakawea reservoir behind the dam isn't affected.

The Minot Daily News reports that the work is expected to be completed later this year.

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Information from: Minot Daily News, http://www.minotdailynews.com