Fences are the most effective defenses against crop damage by deer. If properly constructed and maintained, fences mitigate crop damage. However, it is difficult to enclose farmland completely when a fence crosses a river. This study evaluated the effectiveness of olfactory (wolf urine), visual (flashlight), and sound deterrents against deer at the intersection of river and fence. These deterrents were used for four weeks; the no-treatment control period was also four weeks. The treatments were tested six times. Sensor cameras detected deer intrusions into the fenced area. The sound, flashlight, and wolf urine treatments were 80%, 54%, and 57% more effective in preventing deer intrusions than the control, respectively. Statistically significant efficacy was detected only for the sound treatment. Previous studies reported that sound deterrents were ineffective, but this study revealed efficacy of the sound deterrent; this disparity could be due to the use of an attractant, since most studies employed food to test deterrent effectiveness. The short-term (four-week) tests demonstrated the effectiveness of the sonic device; however, long-term tests revealed that the efficacy declined with long-term usage (habituation effect). Use of the device should be limited, i.e., for no longer than one month.