Abstract: The earth-rock dam with clay core of Shenyugou dangerous reservoir in Fang County is studied, whose seepage and dam slope stability are evaluated, aiming to provide strength design with reference. Three kinds of stable seepage computing conditions such as check flood water table, designed flood water level and normal storing stage are designed and computed. Two types of unstable seepage schemes, from check flood water table to normal storing stage and lowering from normal storing water table to dead water level, are done. Moreover, five kinds of lowering velocities are designed by the latter unstable seepage scheme. Slope stability of dam is calculated at each seepage step. It is found that stability of downstream dam slope doesn’t meet to the engineering requirement under three stable seepages’ and two unstable seepages’ conditions. So the reservoir is a dangerous one, and is in need of strengthening

Key words: dangerous reservoir, earth-rock dam with clay core, seepage, stability