I can see 3 distinct white pixels (or near white atleast) that are spaced evenly, exactly in line with each other. Something might be on the lens or mirror. You have to look at the picture at 100% to see them. One is on the right, in the water, just above the railing, about halfway between the posts. Second is to the left of the small island of trees. On the same level as the first, about the same distance away form the island as the first one is. Third is further left in the water.
You have some in the sky too actually. Put a different lens on the camera and see if they are still there.