Greenways and the environment

I have recently become fascinated with how the greenway movement interacts with the environment and vice versa. The greenway movement is near 20 years of age and is reaching its peak, not only are progressive urban communities constructing extensive greenways, but so are conservative rural small towns. I worked on the planning for a large portion of the Yadkin river greenway in Boone with a transportation engineer with NCDOT. When I think of greenways I think of green space, buffering and stream and providing permanent protection. When I got involved with this project I was shocked to find that the plan’s called for the removal of buffers or neatness and view consideration.
After further research I realized that in principle greenways are good, but there is a large body of literature that refutes there environmental benefits. Things like raising the path elevation to keep flood maintenance costs down and impervious surface lend themselves to huge environmental problems. I often argue that greenways have a free ticket to develop in the floodplain that no other type of development would be approved. Granted, greenways are probably the lesser of two evils. I think this all goes back to a childish romance with anything that sounds, smells, or tastes eco-friendly so it must be good.