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.
Chattahoochee River At Spur 39, Near Omaha, Ga
Yellow R Trib At Plantation Rd,Nr Lawrenceville,Ga
West Point Lake Near West Point, Ga
Swift Creek Near Lithonia, Ga
Talking Rock Creek Near Oakman, Ga
Jackson Creek At Angels Lane, Near Lilburn, Ga
Reed Creek At Blue Ridge Drive Near Martinez, Ga
Flint River At Riverview Plantation, Nr Hopeful,Ga
Jacks Creek At Brannan Road, Near Snellville, Ga
Wolf Creek Tributary At Dean Road, Nr Suwanee, Ga
Chattahoochee River At Morgan Falls Dam, Ga
Sweetwater Creek At Us 29, Near Luxomni, Ga
Lake Kedron Near Peachtree City, Ga
Flint River At Ga 26, Near Montezuma, Ga
Kinchafoonee Creek At Century Rd,Near Leesburg,Ga
Sewell Mill Creek At Ga 120, Near Marietta, Ga
Alcovy River Below Covington, Ga
Noonday Creek At Shallowford Road, Nr Woodstock,Ga
Chattanooga Creek At Ga193, Near Flintstone, Ga
Brushy Fork Creek At Beaver Road, Nr Loganville,Ga
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.