It flows into the Yakima River near Cle Elum.

The river's name comes from Sahaptin, possibly /tyawnawí-ins/, "drying place".

These forks all begins at elevations above 5,000 feet (1,500 m) in the Cascade Range northeast of Cle Elum Lake.

The confluence is located in the vicinity of the Teanaway Community Forest.

[4] After its forks joins, the Teanaway River curves through the Teanaway River Valley, flowing east, then west, then south to join the Yakima River near Teanaway.