How does Almanac score fishability?

How does Almanac score fishability?

Almanac's fishability score is a per-river rating (Excellent / Good / Fair / Poor / blown-class outcomes) built mainly from live flow relative to each river's historical optimal zone, water temperature bands for the active target species, clarity, weather context, and storm-lifecycle state — then rolled into the public Alley Index as a 0–100 average across reporting rivers. Fishability on Almanac means how workable a river is right now for the species mode in season — steelhead in the cool season, warm-water targets (often smallmouth) when summer scoring is active. It is not a guarantee of catch rate. Flow is USGS (and proxy) discharge compared with each river's optimal CFS band from historical Good and Excellent reports. Water temperature uses species-aware bands: steelhead prefer cooler water, and warm-water mode shifts both the target and the temperature scoring. Clarity distinguishes stained, clear, and muddy water. Steelhead often prefer some stain; summer smallmouth scoring treats clear water differently. Weather and barometric pressure add forecast modifiers on the recommendation breakdown. Storm lifecycle (active, recovering, or stable) keeps a pretty flow number from being scored as a sweet spot during a blowout. The live engine returns a rating plus a numeric score with a breakdown across flow, temperature, clarity, weather, and pressure. Forecast paths use a simplified projection scorer when a full 24–48 hour history is not available. For each river with a current condition, Almanac maps the fishing rating to a 0–100 river score (Excellent 100, Good 75, Fair 50, Poor 25, blown or peak-class 0). The Alley Index is the rounded mean of those river scores. Rivers are weighted equally so the number stays transparent. Sub-indices for Lake Erie, Lake Ontario, and technique filters use the same math on a filtered set. The public surface is /index. Per-river cards and river pages show the rating, gauge context, and supporting conditions. /index shows today's composite Index, the change, and commentary. Explorer map popups and personal forecast emails reuse the same recommendation family so anglers do not see three conflicting reads. Missing or stale water-temperature readings, and filters that look only at "flow in the optimal zone," have produced false sweet spots in the past. Almanac's fishability composer requires the rating, clarity, temperature range, freshness, and lifecycle together — not flow alone.