Mining-induced seismicity was monitored at Grassy Trail Reservoir in eastern Utah. Coal mining activity at increasing proximity required evaluation and monitoring of potential impacts to the reservoir and earthfill embankment dam. Attenuation relationships for small-magnitude near-source events were used to predict the ground motions at Grassy Trail. Geotechnical instrumentation was installed and monitored on the dam and reservoir rim to allow assessment of impacts as mining drew near. The number of seismic events detected at the reservoir was related to the distance to the area being actively mined, and the intensity of ground shaking at the reservoir appeared to be a function of both distance and event magnitude. A comparison of predicted and recorded ground motions is presented herein, along with a general discussion of the dam's overall performance.