OMAHA, NE — The U.S. Army Corps of Engineers will hold two public meetings to seek comments on the draft environmental assessment (EA) for addressing dam safety issues at the Snake Creek embankment, which separates Lake Sakakawea and Lake Audubon, in Garrison, ND.
The meetings will be held at the following times and locations:
Tuesday, June 19 from 6 - 8 p.m.
Ramada Bismarck Hotel
1400 East Interchange Avenue
Bismarck, ND 58501
Wednesday, June 20 from 6 - 8 p.m.
Garrison City Auditorium
800 S. Third Street
Garrison, ND 58540
The public meetings will include a presentation, starting around 6:30 p.m. each evening, and an open house to provide the public an opportunity to ask questions about dam safety issues at the Snake Creek embankment and provide input on the draft EA. The preferred alternative outlined in the EA includes updating the current Lake Audubon Water Control Plan with a provisional operating restriction to manage lake level differences between Lake Sakakawea and Lake Audubon during drought conditions.
The draft EA may be downloaded at http://www.nwo.usace.army.mil/Missions/Civil-Works/Planning/Project-Reports/. Comments on the report can be emailed to cenwo-planning@usace.army.mil or mailed to: U.S. Army Corps of Engineers, Omaha District, CENWO-PMA-C, ATTN: Amee Rief, 1616 Capitol Avenue, Omaha, NE 68102-4901. Comments must be postmarked or received by July 20, 2018.
Background: Snake Creek embankment, constructed in 1954, is located eight miles northeast of Riverdale, North Dakota and impounds Lake Audubon, which is a sub-impoundment of Lake Sakakawea. As a result of the prolonged period of drought from 2000-2009, USACE conducted a re-evaluation of the Snake Creek embankment underseepage design which identified a dam safety concern due to high pressures in the dam’s foundation during large elevation differences between Lake Sakakawea and Lake Audubon.
To date, USACE has installed additional dam safety instrumentation to relieve foundation pressures and increase underseepage monitoring capabilities; however, the most effective interim risk reduction measure is to implement a provisional operating restriction to manage lake level differences between Lake Sakakawea and Lake Audubon during drought conditions. Implementing an operating restriction would require an update to the Lake Audubon Water Control Plan, which currently does not include guidance when the Lake Audubon pool elevation is higher than Lake Sakakawea.