Crab Creek, Brook in central Washington, United States

Crab Creek is a 163-mile stream in Washington that runs from near Reardan southwest to the Columbia River at Beverly. It passes through Brook Lake, Moses Lake and Potholes Reservoir, and below Smyrna cuts a two-mile-wide canyon between the Saddle Mountains and the Royal Slope.

Before 1904, drifting sand dunes blocked Crab Creek below Moses Lake, so its water did not reach the Columbia River; a large flood that year washed through the dunes and lowered the lake by eight feet. The connection remained intermittent, and only with the Columbia Basin Project did the creek's character change. The O'Sullivan Dam, built from 1947 to 1949, formed Potholes Reservoir, which has no perennial outlet to Lower Crab Creek.

Indigenous Spokane and Palouse peoples established important trails along the creek, utilizing its waters for food gathering and transportation routes.

The creek water is unsuitable for human consumption, so visitors should bring their own drinking water. The water facilities present are designed mainly for livestock and not intended for travelers.

Crab Creek is sometimes called the longest ephemeral stream in North America, yet it is also one of the few perennial streams in the Columbia Basin. Before the Columbia Basin Project, Upper Crab Creek ran dry and there was no year-round flow between Brook Lake and Moses Lake.