Sir George Simpson used the name "Similkameigh" for one of the groups part of the Okanagan Nation.

The transition from Similkameigh to Similkameen may have been inspired by the name of the Tulameen River despite being etymologically incorrect.

"[5] The river's beginning is at Nordheim Peak, on the east flank of Manning Park, about 10.3 km (6.4 mi) north of Allison Pass and flows past the settlements of East Gate, Princeton, Hedley, Keremeos, and Cawston, closely followed by Highway 3, the Crowsnest Highway.

The United States Geological Survey maintains a stream gauge at river mile 15.8, just upstream from the Oroville–Tonasket Irrigation District canal intake.

The authority responsible for overseeing the IJC agreements is the International Osoyoos Lake Board of Control, composed of appointees from Environment Canada, the BC Ministry of Water, Land Air Protection, the US Army Corps of Engineers, the US Geological Survey, and private consultants.