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Provides an update on High Rock Lake's nutrient modeling, addressing impairment history, role of advisory committee, and next steps in developing a Nutrient Management Strategy.
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High Rock Lake Nutrient Modeling UpdatePam Behm - NC Division of Water Resources Environmental Management Commission Information Item January 8, 2015
PURPOSE To provide an update on the status of the High Rock Lake nutrient modeling and information on the next steps in the process of developing a Nutrient Management Strategy for the lake.
OUTLINE • Description of Lake and Watershed • Impairment History • Addressing the Impairment • Role of Technical Advisory Committee • Next Steps
High Rock Lake Watershed Neuse Yadkin Cape Fear
Population: 850,000 High Rock Lake Watershed
47% Forest 30% Pasture/Crop 18 % Developed 2007 Land Cover
Impairment History • Mid-1970s – Highly nutrient over-enriched conditions first documented • 1992 – DWQ NC Lake Assessment Report • One of the most nutrient over-enrichedlakes in NC • Recommended “management strategies” • 303(d) List • Entire lake listed for chlorophyll-a
Addressing the ImpairmentQuestions • Where are the nutrients coming from and how much? • Tool: Watershed Model • What reductions in nutrient loading are necessary to achieve water quality standards in the lake? Nitrogen? Phosphorus? Both? • Tool: Nutrient Response Model
Addressing the Impairment • 2005 – DWQ formed Technical Advisory Committee (TAC) • 2007 – 319-grant awarded to Yadkin/Pee Dee River Basin Association (YPDRBA) for an intensive monitoring study of the lake/watershed • 2009 – EPA contract awarded to Tetra Tech for model development
Estimates what is happening on land that results in nutrient export to receiving water(i.e. High Rock Lake) Provides relative loading by source (agriculture, developed, point sources, etc.) Watershed Model
Watershed Model – NMS uses • Used to: • Determine nutrient concentrations entering High Rock Lake • Assist with evaluation of potential source reduction scenarios • No direct application to NMS
Nutrient Response Model Lake Response Chl-a Result of Model Determines nutrient load reductions that will achieve water quality standards Existing loading from all sources Lake Response Chl-a Reduced loading
Technical Advisory Committee (TAC) WHO: Stakeholders – state and local agencies PURPOSE: Assist … with the development of mathematical tools for the management of nutrients and turbidity in High Rock Lake
High Rock Lake TAC Members • APGI • DHHS – Environmental Health Section • Dept of Transportation • Div of Soil and Water Conservation • DWR • Duke Energy • Keep Iredell Clean • Kernersville • Piedmont-Triad Regional Council • Salisbury • Winston-Salem • Yadkin Riverkeeper
TAC • Modeling Training • TAC Inputs: • Modeling Goals • Monitoring Plan • Model Performance Targets • Model Review – “Tell us how to make it better”
Next Steps • Finalize nutrient response model • Final TAC meeting END of TOOL DEVELOPMENT (Step 1 in NMS Development Process Completed)
Nutrient Management Strategy Development Process Step 1: Build the tools Who: • DWR and TAC What: • Monitoring • Modeling Step 2: Develop the strategy Who: • DWR and Stakeholders What: • Model scenarios • Reduction targets • Point and nonpoint strategies
EMC Role • Nutrient Response Model Approval • Not required for High Rock Lake • Has been required for previous strategies • “Appropriate tool to use for strategy development”
Questions? Pam Behm pamela.behm@ncdenr.gov 919-807-6419