This chapter may not be construed to limit a municipality's home rule authority or its ability to form a watershed district through its interlocal cooperation authority under Title 30‑A, chapter 115 but provides an additional and alternative method for the formation of a watershed district and provides powers supplemental and additional to powers conferred by other laws, and may not be regarded as in derogation of or repealing any powers existing under any other law, either general, special or local.   [PL 2009, c. 506, §2 (NEW); PL 2009, c. 506, §3 (AFF).]