Jody Peterson took the pitching loss for the host Wolverines, allowing eight runs on eight hits and two walks, with four strikeouts.
Jessica Fundermann, Kelsey Wright, and Peterson each had two hits in the game, while Alissa Slota, Shelby Chester, and Trisha Todd also stroked hits.
"Little things cost us a win," said River Valley coach Erika Slota. "The girls didn't give up and were not ready to lose. It was a close one in the bottom of the seventh inning, they wanted it, but came up just a bit short."