Melanistic!
The bird looks to be gray above with a black bill and black feathers on the nape/neck area. The tail appears to not be notched.
Unfortunately the bird was flying around about 1000' away. The pictures aren't clear enough to see the wings well. In some pictures it looks like there are dark portions on top of the wing and there is no good look at the underside of the wing?
The bird flying low over the water, like a large swallow or a nighthawk that was hawking insects. It may have been picking thinks off of the surface but I don't think so, it never landed or plunged into the water.
The eggs of these turtles were in a woodchip pile in Lucy Stone Park. Maintenance volunteers hatched the eggs and let them go into the river 8/16/23