No clue really! I had thought maybe it was a kite at first but the only ones we usually have in Connecticut are Mississippi and Swallow-Tailed Kites and neither fit the bill. White-Tailed Kite has been suggested to me.
Osprey hit my mind to but I've dismissed that as I had seen an Osprey here the day before and it looked different than this. Also, I saw this bird while talking to a lady doing a water test and, after we saw the bird, she said, "You know, we also saw an Osprey last week, too." She couldn't tell me what this was, though.