The three numbers gauges give you
Discharge (cfs) is how much water moves past per second: the river number. Gauge height (ft) is the water's surface level at the sensor: rivers and some lakes. Reservoir elevation (ft above a datum) is a lake's absolute level: compare it to 'conservation pool' (full) to know if a lake is high or low. Every water page on this site pulls these live and charts 30 days of context.
Rivers: fish the trend, not the number
Every river has a personal 'green window': learn it once, use it forever. Rising sharply: blown out soon, fish the first hours or go home. Falling after a spike: the magic window: fish push to feeding stations as clarity returns (steelheaders live by this). Stable low: technical but predictable: downsize. Our river reports flag rising/dropping automatically, and the 30-day chart shows where today sits in the story.
The post-rain hydrograph: the shape every river angler learns to read.
Reservoirs: level trends move fish for weeks
Rising lakes flood cover: bass and baitfish follow the new water into brush and grass: flipping season. Falling lakes pull everything to the outside edges, points and channels: structure season. The change matters more than the level: a lake two feet low and rising fishes 'high'; the same level falling fishes 'low'. Check the vs-pool number and the 7-day arrow on any lake page here before choosing your water.
Beyond flow: the other numbers worth reading
Gauge pages carry more than cfs. Water temperature (where sensors exist) beats any estimate: trust it over models. Turbidity sensors on some rivers quantify 'is it clear enough': under 10 NTU generally means sight-fishing water, over 50 means bait and vibration. And reservoir storage (acre-feet) tells the drought story better than elevation alone. Our water pages surface what each station offers: not every gauge measures everything.
Building your own gauge habit
The professional move is memorizing three numbers for your home water: its blown-out threshold, its prime band and its too-low floor. Then the morning check takes ten seconds: our 30-day charts show today against the month's shape, and the trend arrow tells you tomorrow. After one season of pairing gauge readings with your actual results, you will predict your river better than any generic forecast: that is the entire secret of the locals who always seem to pick the right day.
A five-minute morning routine
The professional check, in order: your water's level or flow and its 7-day arrow (our page, ten seconds); the pressure trend (same panel); wind speed and direction against the banks you planned; and the day's solunar windows against your free hours. Four data points, one coffee: it converts 'let's see how it looks when we get there' into a plan that survives contact with the lake. Every element sits on the water's page: the routine is reading one screen.
Gauge limitations worth knowing
Gauges measure where they sit: a dam-release reading describes the tailwater, not a tributary ten miles down that a storm cell just browned out. Ice throws winter readings on northern rivers; weed growth shifts summer stage readings on slow water; and 'provisional' USGS data occasionally revises. Treat gauges as the best single signal: not gospel: and cross-check with recent rain maps when a number looks too good after weather.
Common questions
What is a good cfs for fishing?
There is no universal number: 300 cfs is a flood on a mountain creek and a trickle on the Clearwater. Compare today's flow to the river's own median (our charts show the recent range) and to the wadeable windows named in each river's guide.