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