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Standard Operating Procedures
Reports and Data
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Lakes are valued for the multiple benefits they provide to the public, including recreational boating, fishing, drinking water, and aesthetic enjoyment. The Division of Water Resources seeks to protect these waters through monitoring, pollution prevention and control, restoration, and public education activities. The Ambient Lakes Monitoring Program (ALMP) originated under EPA's Clean Lakes Program and is designed to identify long-term trends of lakes and reservoirs across North Carolina. The water quality data collected is used to calculate the state of nutrient enrichment (trophic state) and determine if lakes meet their designated use.
Ambient Lake Monitoring Locations
ISB samples approximately 160 lakes on 5-year rotating basin schedule. Lake stations are located statewide.
• Monitoring is performed monthly during the summer (May through September).
Criteria for lakes in the Ambient Lakes Program include:
• Lake must be >10 acres,
Detailed Quality Assurance Program (QAPP) which includes methodology can be found to the left of this page. Physical data such as temperature, dissolved oxygen, pH and specific conductivity are collected from the surface to bottom. Chemical data are collected in the photic zone (zone of light penetration). Common chemical parameters include total residue, total suspended residue, turbidity, chlorophyll a, phytoplankton and nutrients. Hardness is collected at the surface.
NC Trophic State Index:
North Carolina Trophic State Index (NCTSI) is calculated by using chemical and physical parameters to determine the productivity of a lake. The NCTSI formula for this calculation is as follows:
• NCTSI = TONScore+ TPScore+ SDScore+ CHLScore
NCTSI- North Carolina Trophic State Index Scale: