An edition of: WaterAtlas.org Presented By: Orange County, USF Water Institute
Explore the state of water quality in Orange County.
This tool allows you to view current water quality conditions for lakes and rivers utilizing new dashboard technology that features dynamic maps, filters and gauges
Water quality: How is it changing over time? How does it compare in different areas? The analysis on this page helps to answer these questions.
Learn about the anatomy of a spring as well as the factors that affect water quality and how you can help to protect it.
Take a virtual tour of the Wekiva River Protection Area to discover how managed conservation areas are safeguarding water quality.
This interactive map brings all water resource-related information together in one place
Use this interactive map to find data from continuously-reporting monitoring stations
Use this tool to graph water resource data and to download data for your own analysis
View the geographic distribution and variability of rainfall amounts, access statistical rainfall summaries, or download rainfall data
Find a particular water resource on any of the Water Atlas websites using this tool
Learn about this system of 13 interconnected lakes and how it is being managed for water quality and recreation
What can you do to reduce pollution? Here are 10 actions you can take today that will improve water quality, increase biodiversity, and improve ecosystem health in our communities
Educators can use these inquiry-based lesson plans to teach about watersheds, climate change, and resource conservation
Search our library of water-related documents, maps, websites, videos and organizations
Use this mobile-friendly guide to identify exotic invasive plants and find out how to eradicate them
Find information to help homeowners, businesses, and contractors reduce stormwater pollution
Learn how Orange County implements its NPDES Stormwater Program. Employees of Orange County and its co-permittees can refresh their knowledge and test themselves on the NPDES rules.
Check this list to find out who to call to report problems or to ask questions about rules, regulations, and permitting
Be informed about important water-related news from around Orange County and elsewhere
Use this calendar to find opportunities for recreation, volunteering, and citizen participation
Watch these videos to learn how to protect and enjoy Orange County's waterways
See recent and historic photos of area waterways, submitted by Water Atlas sponsors, partners and users
Find out how you can participate in improving Orange County's waterways and watersheds
See a water quality problem happening? Report it here.
Do you have old photos or documents, or an interesting water-related story to tell? Let us know.
Learn how your lakefront community can set up a special taxing district to provide funds for essential lake services such as invasive plant management
The 28 lakes in the Butler Chain and Windermere Water Navigation Control District are known for their excellent water quality, good fishing, and recreational activities
We welcome user submissions of documents, organizations, videos, etc.
This dual analysis allows you to explore short- and long-term trends for those water quality parameters that are most useful in evaluating the extent of nutrient pollution. The trend analysis () shows whether the measured value of a water quality parameter is increasing or decreasing over time, and at what rate. The hotspot analysis () compares the values measured at a sample site in the past year to values measured elsewhere in the county. Taken together, these two results can help you to gain a more complete perspective on water quality. For example, while the Water Quality Trends map might show that a particular measure of water quality is increasing at a certain monitoring location, the Water Quality Hotspots map may reveal that compared to the county as a whole, the values measured at that location are still very low.
HOW TO USE: Use the map to choose a water quality parameter, time period, and geographic area. One map will show a summary of the results of a Seasonal Kendall Tau statistical analysis for trend*. Each icon displayed on the map represents one monitoring station; it shows whether the data collected there for the selected water quality measure shows a statistically significant trend, and if so, whether it was increasing or decreasing, weak (<10% change/year) or strong (>10%/year). Clicking on an icon will open a popup with a trend graph. Click on the "View full details" link in the popup to see a full page of information about the station, data, and trend, and to download a printer-friendly version.
The other map will show a this "hotspot analysis" that allow you to quickly identify where very high or very low values have been measured for selected water quality parameters, relative to other locations throughout Orange County. The map uses color-coding to represent relative frequency distribution, showing for each monitoring station where the median value for a parameter falls, relative to the median values at other stations of the same type. For example, "< 10%" means that fewer than 10% of stations have median values that are lower. "50-75%" means that at least half of all stations have a lower median value, and at least a quarter have a higher value.
This analysis will be performed annually, with results presented in summary form on the map, and detailed results downloadable as an Access database or CSV files. Each year new results will be viewable on this page as they become available.
Note: Trends were prepared on May 17, 2024 using the latest available data.
The nearby map shows the trend being experienced at the long-term monitoring stations spread throughout the Orange County area.
View Data Source Details
You can download raw data for your own analysis by clicking on the link below. The data is formatted as a ZIP file containing raw and calculated data, methods documentation, and an R script.
Download View archived analyses
Archived Analyses
The nearby map shows water quality hotspots at the long-term monitoring stations spread throughout the Orange County area.
† Numeric Nutrient Criteria (NNC) is only available for some water quality parameters
You can download raw data for your own analysis by clicking on the link below. The data is formatted as a ZIP file containing all supporting data.
Note: Most recent hotspot analyses were performed on May 17, 2024 using the latest available data. Results presented replace all previous editions.
For more information, please contact:
For more information, please see the documents below:
This page displays the results of a statistical ten-year trend analysis developed to use selected water quality parameters from the Water Atlas. In addition to a summary visualization of the trend results, it also provides a compiled data set, and explanatory digital documents that will be valuable to natural resource managers as they attempt to characterize and react to water quality conditions and trends. The statistical analytical techniques employed by this tool were modified from the approach used by Janicki Environmental, Inc. in the 2013 Water Quality Data Analysis Report for the Coastal & Heartland National Estuary Partnership. Data used in this analysis must meet requirements for testing/correction of seasonality: i.e., there must be at least four (4) sample values in each calendar month over the course of a 10-year period.
The Seasonal Kendall Tau test for trend available in the EnvStats R package is used as the statistical approach[1]. The model employs techniques to account for seasonality, autocorrelation and duplicate sampling, in an effort to detect statistically significant trends in the data. Analysis was performed on a suite of water quality measures for all available monitoring sites. For each site/water quality measure, the analysis determined whether a statistically significant trend was detected, and if so, whether it was increasing or decreasing, weak (<10% change/year) or strong (>10%/year).
The amount of nutrients entering a water body has important effects on water quality. Plants and animals that live in lakes, rivers and estuaries use these 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 for submerged plants and trigger events that deplete the 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.
1. Millard SP (2013). EnvStats: An R Package for Environmental Statistics. Springer, New York. ISBN 978-1-4614-8455-4, https://www.springer.com.
The last five years of water quality data collected at each monitoring location are used for this analysis. First, monitoring locations are grouped based on their type – bay, freshwater stream, or tidal stream. Then, frequency distribution analysis is performed to define a percentile distribution for each parameter, for each of the three groups. Finally, for each monitoring location, an annual median value is calculated for each parameter, and that median is used to place the monitoring location in the correct percentile range, depending on its group.
Monitoring stations are assigned to a group based on the type of water body monitored (bay or stream) and if a stream, the classification of the stream segment where the monitoring location is located, either freshwater or marine, as determined by the Florida Department of Environmental Protection’s water body ID, or WBID, definition.
As is the case for the Water Quality Trends analysis, the monitoring locations selected for hotspot analysis must meet minimum data sufficiency and seasonality standards (enough data points collected, spread throughout the year).
Data collected by the following agencies were used in preparation of these reports.