Three numbers on a water page change what you tie on and where you fish.
Clarity
Measured with a Secchi disc — a black-and-white plate lowered on a rope until it disappears. The depth where it vanishes is the number.
Three feet of clarity means your lure is visible for about three feet. There, a natural colour and a slow presentation make sense. At one foot the fish hunts by vibration and silhouette, so a dark profile and something noisy beat a realistic finish. Past six feet, go lighter on line and longer on casts.
Oxygen
The number that decides where fish can hold at all. Below roughly 2 mg/L most game fish leave, however good the structure looks. Between 2 and 4 they are there but feeding poorly.
That is why a lake can have perfect edges and still be dead for a month after a hot spell or an algae bloom.
Temperature
Water temperature drives the year: the spawn, where fish sit in the column, how often they eat. We show the range across our readings, not one figure, because a lake measured in March and in August is two lakes.
The date matters as much as the number
Every reading carries its date. Clarity from two years ago and clarity from last month are not the same fact. When a reading is old, treat it as history, not as today.
