Aeromonas hydrophila infection has been described as the cause of necrotizing fasciitis in patients with suppressed immune systems, burns, and trauma in an aquatic setting. The following presents a case in which severe necrotizing fasciitis and myonecrosis of the lower extremity, as well as toxic shock, developed as a result of wound infection from direct contact with brackish water. Mixed aerobic and anaerobic bacteria, including Aeromonas hydrophila, were isolated from the wound culture. This case illustrates that an infection with Aeromonas hydrophila can cause severe necrotizing fasciitis and myonecrosis. Early and aggressive surgical intervention should be implemented immediately after necrotizing fasciitis is diagnosed.