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The new system for managing Yukon placer mining under the Fisheries Act classifies every watercourse in the Yukon River drainage basin according to how suitable the stream is for fish. Below are maps which show the classifications.

A few notes on the maps...

Fish habitat suitability in each stream is predicted according to the stream gradient, how close the stream is to rivers used by Pacific salmon for migration, and water quality.

Gradient is a measurement of the slope of the stream as it descends from higher areas. This is important because streams with shallow or low gradients typically support more fish species and life stages than those with steeper gradients. Also, shallow gradients usually correspond with beneficial habitat features, such as pools, more large woody debris, undercut stream banks and abundant stream-side vegetation.

However, these predicted habitat features and conditions may not be present in streams already affected by placer mining. That’s why the new management system includes a “Previous Development” designation. It adjusts the classification of streams being currently mined, or that were mined in the past. The Previous Development designation reduces the habitat suitability ranking to better reflect actual conditions in the stream. The standards for sediment discharges and stream channel diversions in such streams are less restrictive.

These maps show the final habitat suitability classification and the type of Previous Development that exists (resulting from historic or current activity). Changes may be made on an annual basis following the Adaptive Management Framework.