The hilltops of Cougar Mountain form a rough horseshoe-shape around the Klondike Marsh headwaters of Coal Creek, which runs northwest to Lake Washington through Coal Creek Park. Long Marsh Creek, Far Country Creek, Cabbage Creek, and Wilderness Creek are tributaries of May Creek, draining the south side of Cougar Mountain to Lake Washington. Deeply etching the sandstone precipice on the north and east side, Lewis Creek, Kline Creek, AA Creek, West Tibbets Creek, and Claypit Creek carry their water to Lake Sammamish.