When a certain number of trees have to be removed for the construction of a new bridge, they're typically pushed over with a bulldozer. This method can de-stabilize the stream bank and cause it to erode and release clogging sediment into the water. Instead of pushing over trees that need to be removed, the Tennessee Department of Transportation cuts them near the roots. Leaving the tree roots in place as long as possible helps hold the soil, reducing sedimentation. The payoff for fish is often enormous. For example, when bridge-construction crews used this technique at the State Route 29 bridge over White's Creek in Rhea and Roana Counties, they protected a federally endangered minnow called the spotfin chub from its arch-enemy: mud.
--Apr 25, 2003