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.
Pequest River At Pequest Nj
Pohatcong Crk At Creek Rd Nr Carpentersville Nj
Ramapo River At Pompton Lakes Nj
Cooper River At Haddonfield Nj
Raccoon Creek At Wrights Mill Nj
Mcdonalds Branch In Byrne State Forest Nj
Paulins Kill At Blairstown Nj
North Branch Raritan River Near Raritan Nj
D&R Ca Feeder Us Of Gate At Washington Crossing Nj
Raritan River Below Calco Dam At Bound Brook Nj
Passaic River At Dundee Dam At Clifton Nj
Passaic River At Pine Brook Nj
Musconetcong River Near Bloomsbury Nj
Passaic River At I-80 At Singac Nj
Pequannock River At Oak Ridge Nj
Ramapo River At Dawes Highway At Pompton Nj
North Branch Raritan River At North Branch Nj
Peckman River At Ozone Ave At Verona Nj
Millstone River At Weston Nj
Greenwood Lake At Awosting Nj
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.