Grading method: Buzzards Bay Eutrophication Index (EI). 1992.
What it grades: Measures the degree of eutrophication.
Parameters: Dissolved inorganic nitrogen, total organic nitrogen, chlorophyll, oxygen saturation, and transparency (Secchi disk depth). Does not evaluate bacteria.
Used by: Buzzards Bay Coalition, Buzzards Bay NEP, Pleasant Bay Alliance, Center for Coastal Studies, Town of Chatham
Data sources: Cape Cod Commission’s database, CCS, BBC, NGOs, others.
Ponds and lakes:
Grading method: Carlson Trophic Index (CTI). 1976.
What it grades: Measures trophic status in terms of degree of eutrophication. Parameters: Total phosphorus, chlorophyll and Secchi disk depth.
Used by: 208 Water Quality Plan for Cape Cod, states, lake managers.
Data sources: Cape Cod Commission’s Ponds (PALS) database, towns, NGOs.
Grading method: Natural Resources Defense Council (NRDC). 2004.
Grades drinking water quality in terms of meeting requirements and proposed standards.
Data sources: Consumer Confidence Reports and other publicly available information.
Grading system: converts numerical scores to grades as follows:
For coastal embayments and embayment stations, scores are converted to Acceptable: requires ongoing protection (blue), vs. Unacceptable: requires immediate restoration (red).
For public water supplies, scores are converted to Excellent, Good, Fair, Poor or Failing.