1. Environmental Management Commission Information Item January 8, 2015
High Rock Lake Nutrient Modeling Update Pam Behm - NC Division of Water Resources
Environmental Management Commission
Information Item
January 8, 2015

2. 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.

3. OUTLINE Description of Lake and Watershed Impairment History
Addressing the Impairment
Role of Technical Advisory Committee
Next Steps

4. High Rock Lake Watershed
Neuse
Yadkin
Cape Fear

5. High Rock Lake Watershed
Population:
850,000

6. 2007 Land Cover
47% Forest
30% Pasture/Crop
18 % Developed

7. Point Sources Municipal and Industrial Wastewater

8. Impairment History
Mid-1970s – Highly nutrient over-enriched conditions first documented
1992 – DWQ NC Lake Assessment Report
One of the most nutrient over-enriched lakes in NC
Recommended “management strategies”
303(d) List
Entire lake listed for chlorophyll-a

9. Addressing the Impairment Questions
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

10. 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

11. Watershed Model
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.)

12. 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

13. 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

14. 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

15. High Rock Lake TAC Members
APGI
Keep Iredell Clean
DHHS – Environmental Health Section
Kernersville
Piedmont-Triad Regional Council
Dept of Transportation
Div of Soil and Water Conservation
Salisbury
Winston-Salem
DWR
Yadkin Riverkeeper
Duke Energy

16. TAC Modeling Training TAC Inputs: Modeling Goals Monitoring Plan
Model Performance Targets
Model Review – “Tell us how to make it better”

17. (Step 1 in NMS Development Process Completed)
Next Steps
Finalize nutrient response model
Final TAC meeting
END of
TOOL DEVELOPMENT
(Step 1 in NMS Development Process Completed)

18. 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

19. 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”

20. Questions?
Pam Behm