“Overriding districts”—more commonly known as overlay districts—are superimposed on existing zoning districts. Their regulations supplement existing zoning regulations, and in this ordinance are adopted to protect watercourses and wetlands as well as steep slope areas. The ordinance is intended to preserve the flora and fauna of the community and to maintain high water quality. This ordinance is adopted under the authority of New Hampshire’s Planning and Zoning enabling act, § 674:16, and the state’s Comprehensive Shorelands Protection Act § 483-B:8, which delegates authority to municipalities to protect watercourses.