15 year old female turtle

Northwestern pond turtles are sexually dimorphic (females and males look different). One way to tell female and male turtles apart is that they often have different color patterns on their face and throats. Females have a more speckled throat, while males throats tend to be more solidly white/yellow. Females also often have a "mustache" which are the vertical dark markings on their upper beak.  

Photo taken at Lookout Point Reservoir, Oregon