It may be worth looking at your own deeds, as the land is hard to reach, there may well be a covenant on your deeds giving the farmer/owner of the land, the right to access it through your land.
Your boundary should be clearly marked on your deeds, and you can look at the boundaries on the internet,for instance if you have a fence at the boundary of your land, if your boundary is marked with a "T" this means the fence belongs to you, and you must maintain it.
What may be more interesting is, who owns the stream, if its the local Water Company, it may be them who own the strip of land.
Your boundary should be clearly marked on your deeds, and you can look at the boundaries on the internet,for instance if you have a fence at the boundary of your land, if your boundary is marked with a "T" this means the fence belongs to you, and you must maintain it.
What may be more interesting is, who owns the stream, if its the local Water Company, it may be them who own the strip of land.