Agenda - 08-30-2011 - 1b - Laserfiche WebLink

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Regional Nutrient Management Rules 14 August 2011 nutrient reduction requirements, while other development, such as industrial/ commercial, must meet the targEt of 8 Ibslacre/year N on-site prPOr to using off-site sources to meet the remaining nutrient reductions. The Jordan Lake new_development rules also require the development of a stormwater BMP operation and maintenance program to ensure long-term effectiveness o~ BMPs. A BMP inspection program must also be adopted by local governments. B. Falls Lake Requirements As shown in Table 1 above, the Falls Lake -new development stormwater requirements -are -more restrictive than those in the Jordan Rules. Both the nutrient bading rates and the threshold values included in the -Falls-Rules are-lower than the similar-val-ues included in the Jordan Rules. The-Falls-Rules also require control of the first inch- of stormwater runoff and no difference in pre- or post-development peak flow is allowed. The requirements for off-site nutrient offsets in the Falls Rules are also more restrictive than those included-in the Jordan R-ales. Under the Falls Rules, new development projects less than one acre in size must include at least 30% of needed nutrient reduction on-site while larger projects must include at least ~0% of the needed nutrient reduction on-site. The remaining nutrient-reductions can be achieved in the form of -off- site buy down credits. C. New Deveiopmerrt Implications The Jordan Lake New Development stormwater Program is-under development by staff and will be submitted to DVa/Q in September 2011 as required. As described above, the County intends to enforce sub-watershed-specific stormwater loading rates and development thresholds rather than adopting one uniform set of values for the entire County. Since most development in Orange County within the Jordan Lake watershed is residential and stormwater regula#ions require one acre of disturbance before they apply, it is expected that most new single-lot residential development will not be subject to the new development stormwater rules and as a result not need to develop a stormwater management plan. In the Haw River sub-watershed of Jordan Lake, the nutrient loading targets for- new development are high enough that most new development should be able to meet stormwater runoff targets though current Orange County open space requirements. However, staff- is estimating that some new development in the Upper New Hope arm of Jordan Lake that does meet the County's current impervious surface limits may not be able to avoid the use of engineered stormwater controls to meet the new stormwater targets. Since the runoff targets and disturbance thresholds are strictest in the Falls Lake watershed, most new development, including single family residences, in this watershed is likely to need stormwater BMPs to meet the nutrient requirements.