You need a non-resident fresh water licence. You can get a full year, 8-day or even a 3 day I think. The yearly licence is $55 plus tax. You can buy it online.
Vaseux lake is just north of Oliver. The river/channel runs out the south end of Vaseux toward Oliver. Lots of bass, squawfish (pikeminnow), and some giant carp in Vaseux. Big bass in Osoyoos as well.
You can use big dries or bigger streamers. I even had a great evening of fishing dry mayflies where the river leaves lake one night.