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.
Green River Near Campbellsville, Ky
Elkhorn Creek Near Frankfort, Ky
Barren River Near Finney, Ky
Kentucky River At Lock 4 At Frankfort, Ky
Kentucky River At Lock 2 At Lockport, Ky
Rough River Near Falls Of Rough At Dam, Ky
M Fk Beargrass Cr At Lexington Rd At Louisville,Ky
Beargrass Creek At Brownsboro Rd Nr Louisville, Ky
Muddy Fk At Mockingbird Valley Rd At Louisville,Ky
Nolin River At Kyrock, Ky
Carr Fork Near Sassafras, Ky
Taylorsville Lake Near Taylorsville, Ky
Green River At Greensburg, Ky
Floyds Fork At Fisherville, Ky
M Fk Beargrass Cr At Browns Ln At Louisville, Ky
Floyds Fork Near Pewee Valley, Ky
Floyds Fork Near Mt Washington, Ky
Pond Creek At Pendleton Road Near Louisville, Ky
Chenoweth Run At Gelhaus Lane Near Fern Creek, Ky
Goose Creek At Hwy 22 At Spring Valley, Ky
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.