Willow Waterhole Bayou is a narrow 4-mile-long natural tributary of Brays Bayou. It flows through Houston’s Brays Oaks area—once oil tycoon Walter Fondren's ranch—and Westbury neighborhoods. In the 1940s, when the ranch land was being developed, portions of the original streambed were rerouted. Today the bayou emerges southeast of the intersection of W. Bellfort Blvd. and Fondren Rd. and eventually flows northeast from Braewick Dr. through the Westbury and Willow Meadows neighborhoods.

The bayou, Scout Lake, its weir (similar to a spillway), and the culvert connecting the lake to the basin complex can all be seen at the end of the 500-foot-long Bayou Trail, which begins at the left of The Gathering Place on S. Willow Dr.

In generations past, the bayou was known by people living nearby as “the ditch.” Even today it is generally a quiet stream of muddy water that stays within its banks, with a normal water level between 44.55 and 44.74 feet above sea level.