The water quality of Casco Bay is generally good. Some areas of concern have been identified, however, where anthropogenic inputs of nutrients from point sources or riverine and other nonpoint sources might be causing higher concentrations of nutrients and lower DO levels.
The overall management goal is to protect the bay’s ecosystem. Since 1993, citizen volunteers and professional staff of the Friends of Casco Bay have monitored water quality at 11 profile stations located throughout the bay. Parameters measured include water temperature, nutrients, DO, and water clarity. Data are used to assess temporal and spatial trends of water quality conditions and identify areas where anthropogenic nutrients from point sources or riverine nonpoint sources are causing problems such as low DO levels.
The Casco Bay Water Quality Index was developed as a convenient way to summarize collected water quality data into a numerical score that can be compared to an index scale ordered from best to worst conditions. The index is based on DO percent saturation and water clarity. The index scores are used to rank areas, identify areas of concern, and analyze trends.
Index scores are used to develop color-coded maps of water conditions across the bay. They can be aggregated in a variety of ways depending on the type of information to be displayed and analyzed. Score distributions can summarize conditions over short or long time intervals—from 1 year to an average of a decade. Problem areas are easily identified based on color (Bricker et al. 2007).
Reference:
Bricker, S., B. Longstaff, W. Dennison, A. Jones, K. Boicourt, C. Wicks, and J. Woerner. 2007. Effects of Nutrient Enrichment In the Nation’s Estuaries: A Decade of Change. NOAA Coastal Ocean Program Decision Analysis Series No. 26. National Oceanic and Atmospheric Administration, National Centers for Coastal Ocean Science, Silver Spring, MD. Accessed October 2016. https://yosemite.epa.gov/oa/EAB_Web_Docket.nsf/(Filings)/3BE82A42C7ED8C3585257B120059CB8A/$File/Opposition%20to%20Petition%20for%20Review%20–%20Ex.%2010%20Part1…23.53.pdf.