Agenda - 10-21-2003-10a - Laserfiche WebLink

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Upper Neuse Watershed Management Plan Appendix A Development Ordinance Changes Recommended for Orange County's subwatersheds Orange County's jurisdiction within the Upper Neuse Watershed covers portions of six upland drinking water supply watersheds; this land area constitutes approximately 25 percent of the Upper Neuse Watershed. For each drinking water supply watershed, you will find a brief description of the land area, existing regulations, and recommended changes to the development ordinance. First, there are two important notes: The TAC recommended testing two alternative management scenarios: 5-acre lot zoning and 3- acre lot zoning with a small village allowed per township. A village was defined as a 50-acre area developing under a high density option (up to 70 percent imperviousness). Although the 5-acre lot zoning was the only scenario that absolutely met the non-degradation target (except for the Lake Orange subwatershed where existing zoning is sufficient), for two subwatersheds (West Fork Eno Corporation Lake, and Little River) the 3-acre lot zoning with village exceeded the water quality target by only 1 to 2 µg/I of chlorophyll a which was deemed adequate to address the target. Therefore, both are listed as meeting the target for these two subwatersheds. 2. Modeling demonstrated that Lake Ben )ohnston is more sensitive to alternative management options. The Lake Ben Johnston subwatershed includes the West Fork Eno, Lake Orange, and Corporation Lake subwatersheds and can therefore potentially be impacted by activities that increase loading in those drainages. The West Fork Eno and Lake Orange reservoirs have more storage than Corporation Lake and thus provide more nutrient trapping than Corporation Lake. The trapping allows for different options to be selected for the West Fork Eno and Lake Orange subwatersheds, while still protecting the downstream waters. However, if Orange County wishes to meet the non-degradation target for the Lake Ben )ohnston drinkingwater supply, the remaining drainage in the Corporation Lake subwatershed (i.e., the area below the West Fork Eno and Lake Orange subwatersheds) and the direct drainage to Lake E3en Johnston should be zoned at 1 unit per 5 acres and 5 percent maximum impervious area for new development, or should meet the nitrogen loading performance standard of 1.7 Ibs/ac/yr and phosphorus loading performance standard of 0.3 Ibs/ac/yr, rather than zoning for 1 unit per 3 acres with villages. Northwest Upper Eno Area in Orange County: 9.5 sq. mi. 2.4 percent of land area of Orange County Existing development regulations: ORANGE • 1 unit per 2 acres in Critical Area COUNTY • 1 unit per acre and 12 percent impervious surface area maximum in Protected Area • Stream buffer approximately 100 feet UNRBA May 2003 A-5