Here is a stream restoration expert talking about Bolin Creek in Chapel Hill and how building the paved greenway was beneficial for the creek: “I think intuitively sometimes we think that if you’re going to be this close to a stream, that a natural surface is going to have better outcomes for water quality. What the reality is though is the way that water behaves when we have an unstable surface, like bare earth. It really does make it very difficult for any type of vegetative buffer to take hold. The users on the trail are adding to that with the mechanical wear and tear on the surface that is keeping vegetation from growing up. So by controlling where people are in the corridor, we limit the impact that they have on the corridor and it allows vegetation to come back up and start treating the water as soon as it crosses the paved surface.”