Grants of land bounded upon rivers carry with them the exclusive right and title of the grantees to the center or thread of the stream unless the terms of the grant clearly denote an intention to stop at the bank or margin of the river. Hardt v. Orr, 142 Neb. 460, 6 N.W.2d 589 (1942); Stubblefield v. Osborn, 149 Neb. 566, 31 N.W.2d 547 (1948).