Here is the regualation from the Corp rules regarding their reservoirs

"§ 327.20 Unauthorized structures.
The construction, placement, or existence of any structure (including, but not limited to, roads, trails, signs, non-portable hunting stands or blinds, buoys, docks, or landscape features) of any kind under, upon, in or over the project lands, or waters is prohibited unless a permit, lease, license or other appropriate written authorization has been issued by the District Commander. The design, construction, placement, existence or use of structures in violation of the terms of the permit, lease, license, or other written authorization is prohibited. The government shall not be liable for the loss of, or damage to, any private structures, whether authorized or not, placed on project lands or waters. Unauthorized structures are subject to summary removal or impoundment by the District Commander. Portable hunting stands, climbing devices, steps, or blinds, that are not nailed or screwed into trees and are removed at the end of a day's hunt may be used."

Here is the link to the full set of regulations:

http://www.lrl.usace.army.mil/...id=77
Basically it says if you do not have express permission from the corp of engineers via a license, permit, etc... then you cannot make ANY structure.