Often, large woody debris (LWD) at hydraulic structures is considered hazardous from a performance and public safety perspective. However, the sustainable management of rivers requires the consideration of ecological impacts of LWD such as cover for aquatics and the natural movement of LWD through a catchment. Therefore, this study explores the interaction of natural (nonuniform) LWD with rock weirs through field observations in the Blacksmith Fork River in Utah, USA and laboratory testing at the Utah Water Research Laboratory. The passage probability of individual LWD at rock weirs is observed and tested in an effort to describe the balance between hydraulic structure performance and river ecology via the natural transport of LWD by the river at rock weirs.Results demonstrate that LWD entrapment is a function of rock weir geometry, hydraulic conditions at the weir, and LWD element length and representative diameter. Orientation of LWD elements approaching the rock weir also contributes to entrapment probability. For lesser flow depths, minor accumulations of LWD at rock weirs do not negatively impact the hydraulic performance as evidenced by the head-discharge rating curve.