The Department may develop an overall watershed management plan for the purpose of implementing different policies for waivers and redevelopment. If the Department establishes a watershed management plan for a specific watershed, the Department may develop quantitative control waivers and redevelopment provisions that differ from § 23-1(a)(2)(ii) through (v) and § 23-7. If the Department establishes a watershed management plan for a specific watershed, then the Department may develop separate policies, reviewed and approved by the State Water Management Administration, for providing water quality control. These separate policies may include:retrofitting; stream restoration; pollution trading; design criteria based on watershed management plans developed under <cite data-path="|7|§23-6|(b)">§ 23-6(b) of this Division II</cite>; payment of offset fees that are dedicated exclusively to provide for stormwater management within the same watershed as the proposed development; or other policies developed by the Department. For this purpose, the watershed management plan must:include detailed hydrologic and hydraulic analyses to determine hydrograph timing; include an evaluation of both quantity and quality management and of opportunities for environmental site design implementation; include a cumulative impact assessment of current and proposed watershed development; identify existing flooding conditions and receiving stream channel conditions; be prepared at a reasonable scale; specify where on-site or off-site quantitative and qualitative controls are to be implemented; be consistent with the General Performance Standards for Stormwater Management in Maryland, found in Section 1.2 of the State’s Design Manual; and be approved by the State Water Management Administration. Ord. 02-367 Ord. 10-277