Water Quality Trends

It is important to track improving or degrading water quality health over time. Plants and animals that live in aquatic habitats require nutrients, especially nitrogen and phosphorus, to grow and survive. However, when excessive amounts of nutrients enter the water, negative impacts can occur, such as algal blooms that block sunlight and may trigger events that deplete oxygen in the water and result in fish kills. The indicators shown here are those most valuable in assessing the health of our waterways relative to nutrient pollution.

Total Nitrogen - Period of Record (All Available Data)

Select a water quality parameter and time period to see the trends in Pinellas County. Clicking on an icon in the map will open a pop-up with a trend graph. Additional information can be obtained in the “View full details” link in the pop-up.

View Data Details

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Note: Trends were prepared on November 15, 2024 using the latest available data.

Trend Analysis Downloads

Please visit the following online resources for information, data, and downloads related to water quality trend analyses in Pinellas County:

Map Legend

  • Increasing Trend, Larger Rate Improving
  • Increasing Trend, Smaller Rate Improving
  • No Trend
  • Decreasing Trend, Smaller Rate Declining
  • Decreasing Trend, Larger Rate Declining
  • Pinellas County Watershed Boundary

Map Legend

  • Increasing Trend, Larger Rate Declining
  • Increasing Trend, Smaller Rate Declining
  • No Trend
  • Decreasing Trend, Smaller Rate Improving
  • Decreasing Trend, Larger Rate Improving
  • Pinellas County Watershed Boundary

Map Legend

  • Increasing Trend, Larger Rate
  • Increasing Trend, Smaller Rate
  • No Trend
  • Decreasing Trend, Smaller Rate
  • Decreasing Trend, Larger Rate
  • Pinellas County Watershed Boundary

Contacts

For more information, please contact:

Documents

For more information, please see the documents below:

Trend Analysis Process Overview

The interactive map depicts the results of long-term trend analyses for select parameters. For each site and water quality parameter, the analyses determined whether a statistically significant trend was detected, and if so, whether it was increasing or decreasing, and whether the trend was weak (<10% change/year) or strong (>10%/year). The analysis method used is a modified Seasonal Kendall Tau test, and the details are described in the report "Pinellas County Timeseries Trend Analysis" by Janicki Environmental, Inc., 2014. At least 60 data points over at least a seven-year period are required for this analysis, so sites with fewer data points or a shorter data record will not show a trend result.

Agency Summary

Data collected by the following agencies were used in preparation of these reports.

Agency Period of Record Data Last Loaded Max Year
Pinellas County Department of Environmental Management 9/1/1999 - 5/30/2024 1/18/2025 2024
PINELLAS Water Quality Data 1/2/1991 - 12/9/2022 12/7/2024 2022

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