The authority herein given shall be in addition to and not in derogation of any power existing in any municipality under any statutory or charter provisions which it may now have or hereafter adopt. For all purposes of this article, all municipal corporations shall have jurisdiction for twenty miles outside the corporate limits thereof: Provided, That for stormwater systems, within the twenty miles beyond the municipality's corporate limits the only areas the municipality may serve and supply shall be those areas from which stormwater affects or drains into the municipality.

The jurisdiction and authority provided by this section does not extend to highways, road and drainage easements, and/or stormwater facilities constructed, owned and/or operated by the West Virginia Division of Highways.