The following table provides a list of interpretive rules and policy statements issued by the NC WW/GW Laboratory Certification program. They are meant to clarify existing legislative rules or to provide guidance where a rule does not exist. Where multiple editions of a single reference source may be approved for reporting purposes and where these approved methods may have conflicting or unclear requirements, the NC WW/GW LC program may adopt a single policy based on a single edition to provide consistency in analytical reporting. Even when citing an alternate reference edition, laboratories must adhere to the NC WW/GW LC policy requirement. 

Policies with an asterisk (* ) beside them notate that the policy could be applicable to Field Laboratory certification, depending upon the parameter methods on the laboratory's Certified Parameter Listing

Parameter Policy Revision
General Quality Control Correlation Coefficient for Linear Calibration Curves * 12/2014

Electrode Slope/Efficiency Documentation 


Electronic Signature and Data Storage Policy *


Factory Set Curve Verification *


Manual Integration

  Required Documentation for Sample Collection and Receipt * 2/2021
  Temperature-Measuring Devices Used for Laboratory Operations Policy * 8/2021
  Titrant Standardization * 5/2019
  Traceability Documentation Requirements for Chemicals, Reagents, Standards and Consumables * 3/2020
  SW-846 Method Implementation 7/2020
  Analytical Balance Weights Verification * 4/2020
  Matrix Spike 5/2020
  Chemical, Reagent, Standard and Consumable Expiration Policy* 3/2020
  Duplicate Sample Analyses for Field Parameters Policy* 3/2020
  Mechanical Volumetric Liquid-Dispensing Devices Calibration Policy* 7/2021
  PT Samples Analyzed Same as Routine Samples* 5/2011
  Parameter Specific  
Ammonia/Fluoride Distillation* 4/2019
Bacteria Quanti-Tray Sealer Check 7/2013
  Fecal Coliform MF Consumables Testing 2/2017
  Fecal Coliform MF Reporting 5/2019
  Fecal Coliform Sample Bottle Sterility 9/2016
  Fecal Coliform MF Culture Positive 9/2016
  Bacteriological Reagent Water Testing 2/2018
  Fecal Sludge MPN Analysis Protocol 8/2021
BOD/CBOD Flagging QC Failures in BOD Data 8/2021
  BOD - Checking DO Meter for Drift 8/2021
  Reporting Limit Policy 8/2021
  Neutralizing Total Residual Chlorine in BOD Samples 8/2021
Chlorophyll Chlorophyll Sample Collection, Preservation and Holding Time Policy 


Dissolved Oxygen Dissolved Oxygen Meter Calibration Policy * 4/2020
Free Available Chlorine FAC Hold Time * 6/2019
pH SW-846 pH Calibration Verification * 2/2020
Residue TSS Reporting Limit 9/2014
  TS and TDS Reporting Limit  3/2009
  Method Blank Requirement for Residues  7/2021
  Anti-static Device Requirement for Total and Total Dissolved Solids 6/2021
  Residue Oven Temperature Documentation 7/2021
Turbidity Turbidity Standards * 12/2007
TRC  Total Residual Chlorine - Sealed Standards in a Field Setting * 10/2017
VAR Option 3 DO Measurement  9/2018
  Option 3 Minimum Sample Volume 9/2018


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