Professional Engineers Of North Carolina

SUM 2014

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15 Summer 2014 the Professional Engineer suitability of Jordan Lake — and newly impound- ed Falls Lake — for swimming and water supply. A report — "Water Quality Investigations of Falls and Jordan Lakes" — was presented to EMC in 1983. Portions of the lake were classifed as Class B — suitable and protected for primary recreation (swimming) — and Class A-II — suitable for water supply after treatment — in 1984. Te very shallow upper lake remained Class C since it was the most eutrophic and the shallow water was not conducive to primary recreation. Te entire Jordan Lake watershed also was classifed as nutrient-sensitive waters since the water quality monitoring informa- tion indicated that the lake was eutrophic. Te NSW plan required implementation of moderate controls for TP from point sources (2 mg/L) and voluntary eforts to manage nonpoint sources of TN and TP. Tese and other nutrient-control actions throughout the state prompted the General Assembly to ban phosphate detergents in 1985. Jordan Lake became a popular recreational desti- nation almost immediately after flling. Te towns of Cary and Apex studied and implemented the lake as a water supply source in the early 1990s. Although WQP monitoring continued to indicate that the lake was highly eutrophic in its biennial water quality reports, there was little regulatory action or water quality concern about the lake from 1984 through 2002. Te WQP and EMC did revise water supply classifcations in the mid-1980s, and portions of the lake were reclassifed from A-II to WS-IV as appropriate for a multipurpose reservoir. Subsequent legislative and rule-making actions in the late 1980s and early 1990s, which afected all Class WS waters, required mandatory eforts in portions of the Jordan Lake Watershed to protect the lake as a water supply from development activities and subsequent runof, including stream bufers. In 1997 the General Assembly passed changes to the General Statutes, requiring discharges to waters classifed as NSW to meet efuent limitations for TN and TP implemented as annual mass loadings based on a TN of 5.5 mg/L and TP of 2 mg/L. Tis action was prompted over the water-quality concerns and rules development to protect the Neuse River estuary. Te legislation did allow development of a nutrient response model to justify alternative efuent limitations. Several communities in the Jordan Lake Watershed believed that the TN limitation was not necessary and contracted with a frm to develop a nutrient response model. Te model was completed in 2002 and submitted to the WQP staf within DENR for use. Te WQP staf continued work with the contractor. Te additional water quality data collected for the model and the predictions of the model led the agency to identify Jordan Lake as "impaired" on the 2002 impaired waters [303(d)] list. Te model showed that signifcant reductions in TN and TP were required for waters in the New Hope arm of the lake — including Chapel Hill, Durham and much of the Research Triangle Park — and subse- quently a total maximum daily load was developed for portions of the lake, primarily the upper portions of New Hope arm, and a nutrient management strategy was developed for remaining portions of the watershed. Less stringent controls of TN and TP were required for the Haw River arm of the lake. Recent regulatory actions In 2003, the WQP within DENR initiated a stakeholder process for the development of rules to implement the requirements of the TMDL in the context of an overall nutrient management strategy. Te EMC frst considered reviewed several versions of proposed rules beginning in 2005 and after several iterations of the rules and public hearings, the EMC adopted the Jordan Lake rules in 2008. Tey were approved by the Rules Review Commission later that year. Te rules were quite complicated and included overall nutrient reduction targets as follows: Upper New Hope Arm • TN – 35% reduction from the 1997 to 2001 baseline load of 986,186 pounds per year allocated approximately 52% to point sources and 48% to nonpoint sources. • TP – 5% reduction from the 1997 to 2001 baseline load of 87,245 pounds per year allocated approximately 28% to point sources and 72% to nonpoint sources. Lower New Hope Arm • TN – 0% reduction from the 1997 to 2001 baseline load of 221,929 pounds per year allocated approximately 3% to point sources and 97% to nonpoint sources. • TP – 0% reduction from the 1997 to 2001 baseline load of 26,574 pounds per year allocated to less than 1% to point sources and greater than 99% to nonpoint sources.

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