Baishuihe reservoir is a small single-curvature masonry arch dam (Small-size(1)) built in 1994

and is designed primarily for power generation with flood control as a secondary function. After 30 years of operation

the abutment exhibits defects such as by-pass seepage

localized retaining wall col ⁃ lapses

and insufficient elevation of the protective concrete facing. Therefore

the dam has been classi ⁃ fied as Class Ⅲ. In this paper

the causes of these defects are studied and a comprehensive reinforce ⁃ ment plan is proposed which includes cement curtain grouting for seepage control of the right abutment and reinforcement of the retaining wall at the left dam abutment. Verification results using the rigid- body limit equilibrium method show that

after reinforcement

the safety factor for slip stability of right abutment has improved and the safety margin has increased

while the left abutment maintains a high level of stability; seepage pathways have been sealed

the integrity of local structure has been restored

and major safety hazards have been effectively eliminated. This plan is technically reliable and economi ⁃ cally sound

and can serve as a reference for addressing similar defects in the abutments of aging mason ⁃ ry arch dams.