There's a lot of benefit for riparian vegetation in narrow buffers. You don't get the full pollution control, but shading and erosion prevention are wins on first order and second order streams with , say, 15 foot buffers. Farmland can be expensive and a lot of farmers can't afford 100 to 300 foot buffers. I think you have to work with what's best for both sides. At PVTU, our biggest losers were no buffers. Streams heat up quickly in only 100 yards of bare, naked sun.Allowing the vegetation to grow in a wide buffer is the main thing streams need.
But that has been known for a long time. People knew that and were working on it when I began flyfishing, around 1970, i.e. 46 years ago.
The question is how to get landowners to allow a wide riparian buffer of vigorous vegetation.
Many landowners don't want that.
Even some fishermen don't want that.