Northern Western Pond Turtle

Identifying this turtle from the Red-slider, there is no marking on the Plastron (bottom) of the turtle. The rear peripherals (top rear edges) are smooth on the Pond and jagged on the Slider. Had to see since this turtle had algae growing on the turtle. Also the inguinal scutes (the part of the bridge from carapace to the plastron by the rear foot) is smaller than the Slider.