Very Low	Low	Moderate-Low	Moderate	Moderate-High	High	Very High	Extreme
0% - 40%	40% - 70%	70% - 90%	90% - 110%	110% - 130%	130% - 160%	160% - 200%	>200%

Very Low: Water flow should not represent any danger (class B = a2).
Low: Not as fun, but should be safe even for beginners (class B/C = a3).
Moderate-Low: A bit low, still fun but not very challenging (class C1- = a4-).
Moderate: Challenging but not dangerous for intermediate canyoneers (class C1 = a4).
Moderate-High: A bit high, quite challenging but not too dangerous (class C1+ = a4+).
High: High water, only for experienced swift water canyoneers (class C2 = a5).
Very High: Dangerously high water, only for expert swift water canyoneers (class C3 = a6).
Extreme: Extremely dangerous high water, may be unsafe even for experts (class C4 = a7).

Historical reference pictures used in Waterflow analysis[edit]

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4 Jul 2019 Moderate-Low	28 Dec 2025 Extreme

References:Arroyo Seco - Switzer Falls-20251229222840