Yeah, there’s a watercourse visible on the OS OpenData StreetView imagery. It might be seasonal, if it wasn’t visible when you cycled through.

I originally mapped this as a bridge on a survey in 2019 (changeset 70642115), but I might have been lax about the difference between bridge and culvert.

I’ve added the stream/ditch and changed the bridge to a culvert in https://www.openstreetmap.org/changeset/171142902. Please let me know if that matches what you saw, as I haven’t visited for a few months :)