Map of the area under the "1,310 line" (orange highlight.)

The area around present-day Kettle Falls, with land under 1,310 feet elevation highlighted in orange. On steep shores like the west edge of the lake, that twenty feet passes in a narrow slice of land. But on gentler slopes, like the site of the original Kettle Falls (center-left, on the West shore of the lake,) it takes up a wider stretch of land.