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.
Truckee Rv Nr Sparks, Nv
Truckee Rv At Clark, Nv
Truckee Rv Blw Derby Dam Nr Wadsworth, Nv
Truckee Rv Nr Nixon, Nv
Walker Lake 4 North Ndow
Walker Lake 3 Center Ndow
Walker Rv Nr Mouth At Walker Lake, Nv
Walker Rv At Lateral 2-A Siphon Nr Schurz, Nv
Walker Rv Nr Wabuska, Nv
Lv Wash Blw Duck Ck Conf Nr Henderson, Nv
Lv Wash Abv Three Kids Wash Blw Henderson, Nv
Walker Rv At Snyder Ln Nr Mason, Nv
Truckee Canal Nr Wadsworth, Nv
Walker Rv At Pt Site Blw Weber Res Nr Schurz, Nv
Virgin Rv Blw Conf Of Muddy Rv Nr Overton, Nv
E Walker Rv At Ivy Ranch Brg Nr Mason, Nv
Lv Wash Abv Homestead Weir Nr Henderson, Nv
W Walker Rv Nr Hudson, Nv
Truckee Rv At Glendale Ave Nr Sparks, Nv
W Walker Rv At Hoye Brg Nr Wellington, Nv
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.