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.
Sipsey Fork At Sipsey, Ala
Talladega Creek At Alpine Al
Black Warrior River Below Selden Dam Nr Eutaw, Al
Conecuh River At Brantley Al
Sipsey River Nr Elrod, Al
Fish River Near Marlow, Al
Mulberry Creek At Jones Al
Cahaba River Near Marion Junction Al
Murder Creek Near Evergreen Al
Hillabee Creek Near Hackneyville Al
Choctawhatchee River Near Newton, Al.
Town Creek Near Geraldine Al
Clear C At New Hope Church Nr Poplar Springs, Al.
Locust Fork At Sayre, Al.
Tombigbee River Bel Bevil L&D Nr Pickensville, Al.
Flint River At Brownsboro, Al.
Cahaba River At Centreville Al
Conecuh River At State Hwy 41 Near Brewton, Al.
Valley Creek Near Oak Grove Al
Tallapoosa River Nr New Site, Al.(Horseshoe Bend)
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.