A barrier that has upstream tributaries of different size classes, such as small streams, small rivers, and large rivers, would contribute a more complex connected aquatic network if it was removed. In contrast, a barrier with fewer upstream tributaries may contribute few if any size classes to the network if removed. In general, a more complex network composed of a greater range of size classes is more likely to have a wide range of available habitat for a greater number of aquatic species.
Barriers that do not contribute any additional size classes are less likely to contribute a wide range of aquatic habitat.
Barriers that have several size classes upstream are more likely to contribute a more complex network with a greater range of aquatic habitat for a greater variety of species.