Easements shall be established for all stormwater management facilities,
including, but not limited to, BMPs and natural and man-made drainageways,
with a width not less than 20 feet adequate to preserve the unimpeded
flow of drainage and to encompass the one-hundred-year water surface
elevation of the facility. The terms of the easement shall prohibit
excavation, the placing of fill or structures, and any alterations
that may adversely affect the flow of stormwater within any portion
of the easement. Maintenance, including mowing of vegetation within
the easement may be required.