Bank stabilization must be contained within the applicant's property lines extended lakeward and not to exceed 3 feet from the eroded bank following the contour of the shoreline. Bank stabilization must be constructed as close to the eroded shoreline as possible and must be constructed for erosion control only. Proposed seawalls, which are not deemed necessary for bank stabilization purposes, will not be permitted within the project boundary. The placement of riprap is the preferred method for bank stabilization. In 2004, Ameren Missouri implemented a waiver that allows riprap to be placed below the waterline between March 15 and June 15 as long as no excavation is involved. Riprap must be clean limestone or native rock that is 8 to 12 inches in diameter or larger. Riprap stacked stone (ledge rock) may also be used to stabilize the shoreline. See Riprap Stacked Stone Detail drawing for correct installation.
A minimum of 24 inches of vertical erosion must be evident before a seawall will be considered for bank stabilization. Ameren Missouri will conduct an on-site evaluation for each bank stabilization request before a permit for bank stabilization is issued. Rip-rap, stacked stone with rip-rap, and/or vegetation should be pursued in all cases where vertical erosion is less than 24 inches. In cases where a seawall is permitted, the permittee will be required to place five horizontal feet of riprap at the toe of the seawall.
Seawalls cannot be constructed to gain or reclaim usable property. Seawalls will not be allowed below elevation 658.5 feet, except for cases of extreme erosion. Applications for seawalls below 658.5 feet will require additional documentation or studies and require approval from the Corps of Engineers. Seawalls permitted within a wetland or head of cove area must be constructed landward of elevation 659.5 feet.
Seawalls constructed of concrete or rock can be used if they are environmentally and aesthetically acceptable.
Guidelines for the replacement of existing seawalls are as follows:
- Existing walls shall be stabilized with riprap or a new concrete footing, whenever possible.
- If the wall cannot be stabilized and is located above elevation 658.5 feet, a new wall can be constructed against the existing wall, if the new wall is not below elevation 658.5 feet.
- If the existing wall cannot be stabilized and is located below elevation 658.5 feet, the existing wall must be removed and either installed at the same elevation or brought back to a higher elevation, as specified by Ameren Missouri.
Construction of seawalls cannot occur from March 15 to June 15, if construction requires excavation below the waterline at the time of construction, to minimize the disruption of fish spawning activities.