Hi,
I had a similar situation where there was an opportunity to install leaky dams but the landowner couldn’t have the water spilling onto the surrounding farmland. The watercourse/ditch was quite deep so we just made dams (a series of 5) which are below the top of the bank, but they work really well. There’s a few photos here http://www.westcumbriariverstrust.org/projects/dovenby-project but I’ve got lots more photos of them in storms showing the difference in water level upstream and downstream of the dam without any damage to the farmland. Let me know if more photos would be helpful and I can send some to you. caitlin”at”westcumbriariverstrust.org