The water quality index (WQI) is an index derived from five separate parameter groups
that describe the health of a stream. A WQI may be determined from as few as two of these
parameter groups (one parameter from each of two groups) and is determined for a quarter
of a year. The Water Atlas employs all-source data to calculate a WQI. The possible sources
for this calculation include: SWFWMD, FDEP, USGS, EPCHC and Hillsborough County Stream WaterWatch.
Streams without appropriate data are not coded.
The streams are color coded for "good", "fair" and "poor" WQI levels.
The verbal descriptors for the ranges used are based on an early determination by
stakeholders of the generally acceptable and understood terms for describing
the state of a stream. The terms were then related to the stream segment's (reach)
Water Quality Index (WQI) value. The source for the WQI calculations used by
the Water Atlas is the Florida Water Quality Assessment, 1996, 305(b) (Table 2-7, p 86).
To download data from a specific stream reach, please visit the Data Download Tool.
Read more at our Learn More about WQI page.
When reading any chart or graph, please keep in mind that space and software
limitations may create misleading spatial relationships. The Y-Axis may not
necessarily start at zero, further distorting spatial relationships among the
data. Furthermore, if multiple samples were taken on the same date at different
locations on the water body, multiple values are plotted for that date. This
presentation of the data explains the appearance of vertical lines on some of
the graphs. If you need to see accurate spatial relationships, we highly
recommend that you use the Data Download section, download the available data,
and graph according to your needs.
To download data, visit the
Data Download Download tool within the Analysis area
of the Seminole County Water Atlas.