As the following discussion on the benefits of road obliteration will show, simply gating a road or taking it off of the inventory does not make the impacts or the road go away. When a road is cut across a hillside, it often intercepts subsurface water flow and runs it down ditches and through culverts. There it picks up sediment and is joined by sediment-laden runoff from the roadbed and cut banks before running into a stream. Hence, subsurface water which would have once welled up to clean bull trout spawning gravels now carries sediment from the surface and deposits it onto the spawning gravels, where it smothers the eggs and fry. Surveys conducted by the Bitterroot National Forest show that its few surviving bull trout populations are located in watersheds with the least roads, stream crossings and timber harvest.
Bull trout are absent in watersheds with the most roads, stream crossings and timber harvest.
Roads, including those behind gates and dropped from inventories, continue to produce sediment until they are totally revegetated. Proper road obliteration, which returns the road bed and fill slope to the contours of the land and replaces culverts with natural stream channels, offers our best opportunity to restore health to our heavily roaded watersheds and the fisheries they support. Benefits to Other Watershed Inhabitants Obviously, sediment sensitive westslope cutthroat trout benefit from road obliteration in the same way that bull trout do. There are many species of wildlife, however, which also benefit from the obliteration of roads. Recent grizzly bear research conducted on the Flathead National Forest shows that grizzly bears avoid closed roads as well as open roads.