In what circumstances can a private right-of-way be claimed as a compensable taking?

In United States v. Welch, 217 U.S. 333, 30 S.Ct. 527, 54 L.Ed. 787 (1910), the owner of a tract of land claimed a compensable taking when his private right-of-way across the lands of others was flooded as a result of the government's construction of a dam. The court held that the right-of-way was an easement, which in turn was an interest in land, and that the taking thereof entitled its owner to compensation. The court valued the loss of the easement by reference to its value to the dominant estate. In Welch, the before-and-after valuation of the dominant estate was employed to calculate the loss in the context of a complete physical destruction of the easement.