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.
Hudson River Above Lock 1 Near Waterford Ny
Schoharie Creek At Schoharie Ny
Pepacton Res Div Outlet Nr Grahamsville Ny
Cohocton River At Bath Ny
Cannonsville Reservoir Near Kelsey Ny
Niagara River At Youngstown Ny
Normans Kill At Karlsfeld Ny
Tioughnioga River At Lisle Ny
Seneca River Near Baldwinsville Ny
Pepacton Reservoir Near Lewbeach Ny
Niagara River At Joseph Davis State Park Ny
Hudson River At Stillwater Ny
Mohawk River At Rexford Ny
Susquehanna River At Binghamton Ny
Niagara River At Lewiston Ny
Esopus Creek Below Lost Clove Rd At Big Indian Ny
Chestnut Creek At Mouth At Grahamsville Ny
S Br Eighteenmile Cr At Bley Rd At Eden Valley
Mongaup River At Mongaup Valley Ny
Stony Clove Cr At Janssen Rd At Lanesville Ny
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.