The West Road River or Blackwater River or Tiyakoh is an important tributary of the Fraser River, flowing generally north-eastward from the northern slopes of the Ilgachuz Range and across the Fraser Plateau in the Chilcotin region of central British Columbia, Canada.

[3] The river is of significant historical importance to both First Nations and Canadian history.

For centuries, the Dakelh (Carrier) and Tsilhqot'in peoples used a trail—the so-called "Grease Trail"—on the northern side of the river in their trade with coastal First Nations communities.

The name Grease Trail refers to one of the main commodities transported along the route—eulachon grease, a highly prized staple, traces of which coated parts of the route after centuries of use.

It was this trail that Sir Alexander Mackenzie used in his historic overland journey west to the Pacific Ocean in 1793, traversing the river itself on his return.