Any existing and, when allowed by the Council, proposed ditches, drainageways, or swales conducting water through or adjacent to a site shall be maintained by the abutting property owner to the curb line or edge of paving, in the case of a roadside ditch, or by the property owner to the property line, in the case of other ditches, drainageways, and swales. The maintenance shall include clearing and mowing to allow natural channel flows and prevent nuisances. Where development or construction occurs around existing drainageways, ditches, or swales, the following will be considered:
1. Where practicable, they shall remain in natural condition.
2. When relocation is permitted, they shall be constructed to a maintainable slope and not unduly increase flood potential and/or damage downstream.
3. The channel, if reconstructed, shall not have less capacity than that of the existing channel.
4. The floodway shall be preserved so as to provide safe passage of the design flood.
5. A maintainable slope shall be considered to be a slope of 3:1 fall.