Stream Access Rights Buried in Deed Language Almost Broke Me

I used to believe that buying land along a creek meant I'd automatically control who could walk that stream corridor. Dead wrong. When I purchased 40 acres along a tributary here in southwest Montana, I found out after closing that a prescriptive access right had essentially been established by neighboring ranchers using that streambank for decades. Their cattle had been watering there long enough that fighting it would've been expensive and ugly. Here's my hard stance: before you close on ANY riparian property, you need a title search specifically examining historic use patterns along the water, not just standard easement language. Standard title insurance won't protect you from established prescriptive rights that were never formally recorded. I learned that from a lawyer who specializes in water law, not from my closing agent. The deed looked clean. The access situation absolutely was not. Anyone else discovered that their streambank situation was legally messier than the paperwork suggested — or does this vary significantly depending on your state's prescriptive easement thresholds?