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, towns and others.
Embayments were graded as Acceptable if all stations in the embayment were graded as Acceptable. If at least one station in the embayment was graded as Unacceptable, the embayment was graded as Unacceptable.
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: Cyanobacteria Monitoring
What it grades: Whether the pond met criteria for the posting of an advisory for cyanobacteria during the season. Parameters: recorded occurrence of a cyanobacteria bloom, high cell counts, or expected high concentrations of toxins according to monitoring data.
Used By: APCC Cyanobacteria Monitoring Program, the Town of Barnstable Health Department, and town health agents
Data sources: APCC Cyanobacteria Monitoring Program, the Town of Barnstable Health Department, and recorded advisory postings by other town health departments.
Final pond grades incorporated the two types of grades, Carlson Trophic Index grades and Cyanobacteria grades. If only one type of grade was available, that grade was used as the final pond grade. If both types of grades were available for a pond, the pond was graded as Acceptable if both grades were Acceptable. If at least one of the two types of grades was Unacceptable, the pond was graded as Unacceptable.
Drinking water quality is graded based on the finished water quality meeting state and federal drinking water requirements and 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 ponds and lakes, 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.