Project Reports

Omaha District seeks public comment for Garrison Spillway Approach Channel Rehabilitation Draft Environmental Assessment

USACE Omaha District
Published Aug. 17, 2022
Expiration date: 9/17/2022

The U.S. Army Corps of Engineers, Omaha District announced it is seeking public comment for a Draft Environmental Assessment for the Garrison Spillway Approach Channel Rehabilitation through September 17, 2022.

The draft EA was prepared to identify potential operation and maintenance solutions to correct deficiencies identified with the Garrison Dam, Lake Sakakawea Project located near Riverdale, North Dakota in McLean County. This draft focuses on identifying a feasible alternative to repair and maintain a functioning bubbler system, allow for operation of the Tainter gates as described in the Garrison Dam Operations Manual, and restore spillway capacity while considering environmental effects.

Evidence indicates that the bubbler system for the spillway Tainter gates at the Garrison Dam, Lake Sakakawea Project is not functioning properly due to sediment accumulation in the spillway’s approach channel. The bubbler system is necessary to prevent ice accumulation on the gates and to permit safe emergency wintertime gate operations. An inoperable bubbler system would result in ice buildup on the Tainter gates in the winter and inhibit the placement of stop logs during annual and routine maintenance.

In addition to covering the bubbler system, the sediment accumulation has also reduced the design condition capacity of the spillway approach channel. The onset of sediment accumulation in the spillway channel was exacerbated in 1975 when riprap on the east embankment was removed and not replaced.

This draft environmental assessment was conducted in accordance with the National Environmental Policy Act of 1969, as amended, Council on Environmental Quality’s regulations for implementing NEPA (40 CFR § 1500-1508), the U.S. Army Corps of Engineers Engineering Regulation 2002-2 (33 CFR 230), and to comply with other applicable environmental laws and executive orders.

Comments can be mailed to: U.S. Army Corps of Engineers, Omaha District; CENWO-PMA-C; ATTN: Rebecca Podkowka; 1616 Capitol Avenue; Omaha, NE 68102-4901. Comments may also be emailed to:  

A copy the draft EA is available for viewing or download at:

All comments must be postmarked or received no later than Sept. 17, 2022.