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.
Big Nemaha River At Falls City, Nebr.
Elkhorn River At Norfolk, Nebr.
Niobrara River At Mariaville, Nebr.
Big Blue River At Barneston, Nebr.
Platte R, J2 Outflow And S Ch, Near Overton, Nebr.
Platte River Nr Fremont, Nebr.
Missouri River At Hwy 92 At Omaha, Nebr.
Cole Creek At Blondo Street At Omaha, Nebr.
South Papillion Creek Near Gretna, Nebr.
Missouri River Blw Ponca Creek Nr Verdel, Nebr.
Big Papillion Creek Near Kennard, Nebr.
Big Papillion Creek Near Blair, Nebr.
Missouri River At Niobrara, Nebr.
Thomas Creek Near Bennington, Nebr.
Springfield Creek At Springfield, Nebr.
Missouri River Near Maskell, Nebr.
West Papillion Creek At Pacific St At Omaha, Nebr.
South Blackbird Creek At Hwy 75 Near Macy, Nebr.
Offutt Ditch (Bellevue Drain) Nr Offutt Afb, Nebr.
Papillion Cr At Harlan Lewis Rd Nr La Platte, Nebr
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.