Coldwater River, River in British Columbia, Canada

The Coldwater River rises west of the Coquihalla Lakes on the northeastern slopes of the North Cascades and flows about 94 km northeast to enter the Nicola River at Merritt. Its cobble-bedded, irregularly meandering channel is 10 to 25 m wide, with abandoned channels forming low-lying wetlands. It passes through Interior Douglas Fir forest, then drier Ponderosa Pine/Bunch Grass, and holds coho and Chinook salmon, steelhead, bull trout and rainbow trout.

Nlaka'pamux peoples have lived in the Coldwater valley at least since the early 1800s; the Coldwater Band's main reserve is Coldwater 1, with Paul's Basin IR 2 to its southwest and Gwen Lake 3 on Gwen Lake. In 1848 and 1849 the Hudson's Bay Company tested a Kamloops–Yale trail through the valley via Nicola Lake and the Coldwater, rejected as too arduous. A 2-metre-wide cattle trail linking Hope and Merritt via the Coquihalla Pass was built in 1872–1876 and destroyed in the 1910s by Kettle Valley Railway construction.

The river's Shuswap name, Tsillatko (also recorded as Ntstlatko), translates as "cold water". The English name Coldwater River is first documented in 1875, and G.M. Dawson's 1877 map of the Southern Interior of B.C. is the earliest to adopt it. The Coldwater First Nation's main reserve, Coldwater 1, lies along the river.

The river is followed for almost 39 km by Highway 5 (Coquihalla Highway), which crosses it at the Kingvale Interchange; a Canadian Pacific Railway line runs along the northern part. Its canyon, 7 km long, lies north of Brodie. Summer low flows come in late August and September, and peak flows in May and June.

The river's Shuswap name, Tsillatko (also recorded as Ntstlatko), means "cold water"; the English name is first documented in 1875 and appears on G.M. Dawson's 1877 map of the Southern Interior. Its temperature stays below 10 °C until early July, about a month later than the Nicola.