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.
Frio Rv At Leakey, Tx
Adams Bayou At Fm 3247 Nr Orange, Tx
Little Blanco Rv At Fm 32 Nr Fischer, Tx
Berry Ck At Fm 970 Nr Florence, Tx
Austin Bayou At Sh 35 Nr Liverpool, Tx
Frio Rv At Tilden, Tx
Crystal Ck At Fm 1314 Nr Conroe, Tx
Pecos Rv At Fm 3398 Nr Pecos, Tx
Poesta Ck At Beeville, Tx
Sabinal Rv At Utopia, Tx
Cole Ck At I-10 Nr Orange, Tx
Oyster Ck At Cr 34 Nr Angleton, Tx
Housen Bayou At Sh 87 Nr Hemphill, Tx
Piney Ck At Us 59 Nr Corrigan, Tx
Brushy Ck At Fm 685 Nr Hutto, Tx
Goose Ck Nr Mcnair, Tx
W Fk Trinity Rv At Us Hwy 281 Nr Windthorst, Tx
Colorado Rv Abv La Grange, Tx
Peach Ck Nr Cleveland, Tx
Cowhouse Ck At W Range Rd Nr Ft Hood, Tx
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.