I found this turtle on the bike path along the Charles River, a little East of River Street, where there's thick vegetation blocking access to the river, which runs very close to the road. It was facing the road on the pavement, head and feet tucked. I didn't find any obvious injury when I picked it up and examined it, and carried it (while walking my bike, which was awkward) towards one of the boat club docks.

A couple of strangers stopped to admire the turtle, and I ended up posing for pictures with them. Then, I found access to the water, and it perked up and rushed straight in. It was perhaps 4lbs and 10" long - quite a substantial specimen.

I was pretty sure it's a red-eared slider, but then the man claimed it was a painted turtle. Now I look again, and it's clearly the former.