South Dog Mountain Falls is a 127-foot waterfall in King County, Washington, in the North Cascades region. It lies about 14.1 miles northeast of Tanner and roughly 27.4 miles east of Sammamish as the crow flies.
At 127 feet it is taller than the typical Washington waterfall of about 82 feet, ranking 326th of 941 with a recorded height. By form it is a horsetail, where the water keeps some contact with the bedrock as it falls.
The North Cascades are a wilderness of jagged peaks, glaciers and deep, forested valleys of western hemlock, silver fir and Douglas fir, with some of the heaviest snowfall in the country. Meltwater from glaciers and snowfields pours down thousands of feet of cliffs in countless cascades and horsetail falls.
King County holds 236 recorded waterfalls, and several are close by. Marten Creek Falls, a 141-foot tiered horsetail waterfall, is under a mile away. Upper Marten Creek Falls, a 149-foot tiered horsetail waterfall, is under a mile away. Treen Falls, is about 1.3 miles away.
South Dog Mountain Falls is located at 47.5912° N, 121.4968° W. The listing is based on the World Waterfall Database, one of the sources compiled by the U.S. Geological Survey in its inventory of waterfalls and rapids of the conterminous United States. The exact position has not yet been verified on aerial imagery, so treat the map pin as approximate. Details on trails, parking and access have not been documented for this waterfall yet.