(A) Any increase in upstream flood stages greater than 0.0 foot when compared to the existing conditions, for all flood events up to and including the 100-year frequency event shall be contained within recorded easements or the channel banks (or within existing vertical extensions of the channel banks) such as within the design protection grade of existing levees or flood walls or within recorded flood easements. A permit or letter indicating a permit is not required must be obtained from IDNR-OWR for any structure built for the purpose of backing up water in the stream during normal or flood flow. All dams and impoundment structures as defined in § 152.002 shall meet the permitting requirements of 17 Ill. Adm. Code, Chapter I, IDNR Part 3702 (Construction and Maintenance of Dams).
(B) If the proposed activity involves a modification of the channel or floodway to accommodate an impoundment, it shall be demonstrated that:
(1) The impoundment is determined to be in the public interest by providing flood control, public recreation, or regional stormwater detention;
(2) The impoundment will not prevent the migration of indigenous fish species, which require access to upstream areas as part of their life cycle, such as for spawning;
(3) The impoundment will not cause or contribute to degraded water quality or habitat conditions. Impoundment design should include gradual bank slopes, appropriate bank stabilization measures, and a pre-sedimentation basin;
(4) A non-point source control plan has been implemented in the upstream watershed to control the effects of sediment runoff as well as minimize the input of nutrients, oil and grease, metals, and other pollutants. If there is more than one municipality in the upstream watershed, the municipality in which the impoundment is constructed should coordinate with upstream municipalities to ensure comprehensive watershed control;
(Ord. 3187, passed 1-22-19) Penalty, see § 152.999