Red-eared slider (melanistic male)

Melanistic (old) male red-eared slider. (see ID suggestion) This one appears to have survived some shell trauma on his left side.

Aaron what would you say they are ?

He's one the guys from California Herps

These are incredibly common in my area and I see A LOT of them. :-)

This came from an expert: I'm afraid I don't know what it is. You really need to see the full head to get an ID. Large old red-eared sliders often do not have red on the head. It seems like I can see a trace of a red patch behind the eye with a faint amount of red. This might be due to the photo, but it could be a slider. I don't know why the shell is yellow. That seems unusual.

I am asking an expert. But I'm guessing a pet dump.

http://www.californiaherps.com/identification/turtlesid/turtles.id.html

how about some yellow?

If the face is striped and has a red patch on the sides of it's face, yes

Not really. That happens with exposure and age and chemicals. Unless it was a pet from out of California, you only have a few species from CA it could be and I narrowed it down to two.

Do you have another angle? If this has stripes and red on the side of the face it's most likely a Red-eared Slider-Trachemys scripta elegans If it has spots or marbled it maybe a Pacific Pond Turtle -Actinemys marmorata