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.
South Fork Mckenzie River Near Rainbow, Or
Mid-North - Upper - Mdnu
Mid-North - Lower - Mdnl
Cow Creek Near Riddle, Or
Klamath River Abv Keno Dam, At Keno - Bottom
Upper Klamath Lake At Howard Bay, Or
Middle Fork Willamette River At Jasper, Or
Rogue River At Raygold Near Central Point, Or
Pudding River Near Woodburn, Or
Rattlesnake Point - Rpt
Santiam River Near Jefferson, Or
Deschutes River Near Culver, Or
Fanno Creek At Durham, Or
Long Tom River Near Alvadore, Or
Klamath Straits Drain Above F-Ff Pumps, Worden, Or
Donner Und Blitzen River Nr Frenchglen Or
Mckenzie River Blw Leaburg Dam, Nr Leaburg, Or
Crabtree Creek Near Scio, Or
Elk Creek Near Trail, Or
Columbia River, Left Bank, Near Dodson, Or
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.