US Water Quality Index
Our composite Water Quality Score combines temperature, reservoir levels, and flow rates to rate conditions for swimming, fishing, and recreation.
How We Calculate Water Quality Score (0–100)
Maximum points when water temp is near ideal 71.5°F (22°C) for most recreational activities.
Full points when reservoir is at or near full pool capacity. Low levels reduce score.
Moderate, stable flow (100–5,000 cfs) earns full points. Extreme highs or lows reduce score.
Little Withlacoochee River Near Tarrytown, Fl
South Fork Little Manatee River Near Wimauma Fl
Levee 31 North Extension At 3 Mile Nr West Miami F
Harney Pond Canal 2.4 Miles Bl S70 Nr Lakeport, Fl
Hillsborough R Bl Crystal Spr Near Zephyrhills Fl
Popash Creek At Leetana Rd. Nr North Fort Myers,Fl
Bonnet Creek Below Culverts Near Kissimmee, Fl
Brooker Creek Near Tarpon Springs Fl
Little Charlie Creek Near Mouth Near Wauchula Fl
Anclote River At Little Rd Near Elfers, Fl
N.W. Wellfield Canal Nr Dade Broward Levee Nr Penn
Turkey Creek At Palm Bay, Fl
Withlacoochee River Nr Pineola, Fl
South Prong Alafia River Near Ft Lonesome Fl
Shingle Creek At Airport Near Kissimmee, Fl
Howell Creek At State Hwy 434 Near Oviedo, Fl
Tamiami Canal At S-12-A, Nr Miami, Fl
Cypress Creek Tributary Nr Wesley Chapel Fl
Saddle Creek At St.Hwy 542 Near Lakeland Fl
L-28 Canal Above S-140 Near Clewiston, Fl
Understanding the Water Quality Index
The US Water Quality Index is a composite score designed to give anglers, swimmers, boaters, and outdoor enthusiasts a quick, at-a-glance assessment of water body conditions. Unlike traditional water quality indices that focus on chemical pollutants (which require laboratory analysis), our index uses real-time USGS sensor data to reflect physical conditions relevant to recreation.
Temperature Component (40 points)
Water temperature is the most important factor for recreational fishing, swimming, and wildlife activity. The ideal range for most activities — comfortable for swimming, optimal for bass and walleye fishing — is approximately 65–78°F (18–26°C). Our scoring peaks at 71.5°F and decreases proportionally as temperature moves away from this ideal.
Reservoir Level Component (30 points)
Reservoir levels (measured as a percentage of full pool) reflect drought conditions, drought recovery, flood risk, and overall ecosystem health. A reservoir at full pool (100%) scores maximum points. Severely depleted reservoirs — common during drought — score fewer points. This metric is particularly relevant in western states where water storage is critical.
Flow Rate Component (30 points)
River discharge (measured in cubic feet per second, cfs) indicates safe boating, wading, and kayaking conditions. Moderate, stable flow rates between 100–5,000 cfs are typically ideal for most recreation. Extremely high flows indicate flood risk, while extremely low flows suggest drought stress and limited habitat for fish.