Aquatic Barrier Prioritization ToolAquatic Barrier Tool

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Network length

Network length measures the amount of connected aquatic network length that would be added to the network by removing the barrier. It is the smaller of either the total upstream network length or total downstream network length for the networks subdivided by this barrier. This is because a barrier may have a very large upstream network, but if there is another barrier immediately downstream, the overall effect of removing this barrier will be quite small.

Low network length

Barriers that have small upstream or downstream networks contribute relatively little connected aquatic network length if removed.

High network length

Barriers that have large upstream and downstream networks will contribute a large amount of connected aquatic network length if they are removed.


  1. The total upstream length is calculated as the sum of the lengths of all upstream river and stream reaches.
  2. The total downstream length is calculated for the network immediately downstream of the barrier. Note: this is the total network length of the downstream network, not the shortest downstream path to the next barrier or river mouth.
  3. Network length is the smaller of the upstream or downstream network lengths.