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Regional Nutrient Management Rules 13 <br />August 201.1 <br />review and BOCG approval, staff estimates the new stormwater requirements may <br />become effective in July 2D12. <br />A. Jordan L-ake Requirements <br />The primary new development requirement concerns the control of nutrients in <br />stormwater runoff. stormwater control, and as a result a reduction.-in the ~oracentration <br />of nutrients- leaving the site, is accomplished through the construction of stormwater <br />BMPs, such as bioretention devices or stormwater wetlands. Currently, BMPs are <br />required on some development projects in Orange County-. Table 1 and Figure 3 <br />compare the nutrient loading r-equirernents and disturbance threshold values for the <br />Falls Lake watershed and each of the Jordan Lake sub-watersi~eds, as included in the <br />nutrient management ales. Staff is proposing tv enforce the different loading targets <br />and disturbance thresholds fog eaach of the different sub-watersheds as shown in the <br />table. <br />Table 1. Comparison of Falls Lake and- Jordan Lake New Development <br />stormwater Rules <br /> iVitrogen Phosphorus Disturbance <br />Watershed Loading-Target Loading Target Threshold <br /> (Ibs/ac/yr) (Ibs/ac/yr) <br />Upper New Hope 2 2 0 82 Comm./Indus. - 0.5 acre <br />Arm of Jordan Lake Residential - 1 acre <br />Haw R-fiver Arm of 3 B 43 <br />1 Comm./Indusr- 0.5 acre <br />Jordan Lake . Residential - 1 acre <br />Entire Falls Lake 2 2 33 <br />0 Comm./Indus. -12,000 sq ft <br />Watershed . Residential - 0.5 acre <br />In addition to the nutrient loading restrictions, new development must adhere to the <br />following additional stormwater s#andards: <br />• No net increase in peak flow leaving the site for the 1-year, 24-hour storm-event, <br />when compared to predevelopment conditions. <br />• Must aaso control the first inch of stormwater runoff. <br />Alternatively, proposed new development may satisfy the requirements by meeting the <br />post-development hydrologic criteria included in Chapter 2 of the most recent version of <br />the North Carolina Low Impact Development Guidebook. <br />The Jordan Rules also allow developers to meet a portion of their nutrient reductions <br />off-site, once a minimum specified reduction is met on-site. For residential <br />development, the project must be designed such that runoff leaving the site does not <br />exceed 4 Ibs/acre/year N prior to using off-site offset sources to meet the remaining <br />