Bumping Lake, Washington state, United States

Bumping Lake is a natural lake on the Bumping River in Yakima County, Washington, enlarged into a reservoir by a 60-foot (18 m) earthfill dam built in 1910 and modified in the 1990s. Its dark, rippled surface stretches to a far shoreline, with a narrow island of tall conifers sitting slightly right of center and a larger stand of conifers on the left where the water meets the shore. Bare pale sticks lie in the shallow water over a rocky bed near the lower right edge.

Bumping Lake appeared as Lake Plehnam on Preston's Map of Oregon and Washington in the 1850s and as Tannum Lake on the 1897 General Land Office map of Washington. A 60-foot earthfill dam, built in 1910 and modified in the 1990s, turned the natural lake into a storage reservoir of the Yakima Project.

Access is via Forest Road 70, which winds through forested land and is open in summer but can be blocked by snow in winter. The lake offers simple camping spots and fishing areas, but there are no shops or rental services nearby, so visitors should bring all needed supplies.

The lake serves as part of the Yakima Project, providing irrigation water to fruit farms in the lower Yakima Valley during the growing season. With storage capacity exceeding 33,000 acre-feet, it plays a key role in sustaining regional agriculture.