A bit south of Smilkameen - Chopaka Wildlife Area is Palmer Lake.
Palmer Lake viewed from the southeast
Smilkameen River valley with Hurley Mountain on left
The relief from Smilkameen valley to mountain summit is 6,500 feet
The lake is within a deep valley that was at least in part modified by continental glaciation. The valley was carved at least in part by glacial ice that extended well south of the lake. As the glacial ice retreated during the late stages of the last glacial period the lower end of the present Smilkameen was blocked by the Okanogan ice lobe and water flow was diverted southward though the deep valley to other outlet locations - such as the valley east of Loomis.
As a result Palmer Lake has some odd hydrology. The Smilkameen River flows south from BC into the valley and then makes a U turn before reaching Palmer Lake and flows east through a narrower canyon to the Okanogan River. However, during high water in the late Spring flood water flows south into Palmer Lake raising the lake level somewhere on the order of 10 feet.
As a result Palmer Lake has two deltas. One from the north associated with an overflow channel from the Smilkameen River and another from the south associated with the Sinlahekin River. The lake also receives groundwater from the high mountains on either side of the valley.