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Bay Conditions

How healthy are our coastal waterways? Collected water quality data give us various measures of ecological health, but taken together, what do they tell us about the overall quality of our coastal systems? How do these measures compare from year to year? From bay to bay? Where has progress been made? Where is more effort needed? These are the questions that this section of the Water Atlas attempts to answer.

The Conditions Overview below gives a comparison of the eight major bay systems that comprise Sarasota's coastal watersheds with regard to three important indicators of water quality. The Bay Conditions Index incorporates all three indicators, or you can view each indicator separately. Ratings are given on a calendar year basis, and are determined by comparing the average value of the selected indicators to target (desired) and threshold (undesirable) levels. Learn more about how threshold values were derived »

To view a page with more detailed condition information for a particular bay system, click on its name below. There you will find high, low, historical and average values for the water quality parameters used in determining the ratings, as well as other important measures of bay health, water quality contour maps, seagrass coverage maps, and watershed land use/land cover characteristics.

Please select a year and parameter. Click on a bay to view a detailed report.
Report Year
Report Parameter

2017 Bay Conditions Index Scores for Sarasota Bays

select a bay to view a detailed report

Bay Conditions Index

The Bay Conditions Index gives a quick assessment of the water quality in each bay during a particular year by examining three important indicators of nutrient pollution: chlorophyll a, nitrogen and phosphorus. The rating system used here was developed by a team of local water resource management professionals, incorporating the "numeric nutrient standards" proposed to the U.S. Environmental Protection Agency and based on research sponsored by the Sarasota Bay Estuary Program.

Each bay receives either a PASS or CAUTION rating, depending on whether sampling values for chlorophyll a, nitrogen, and phosphorus were below maximum thresholds established for that bay. A bay receives a PASS rating only if values for all three indicators are below their respective thresholds; otherwise, the bay receives a rating of CAUTION.

Map Icons
Indicator PASS rating CAUTION rating
Chlorophyll a
Nitrogen, Total
Phosphorus, Total

To view scores for an individual water quality parameter, choose it from the dropdown list above.

Learn more about these ratings »