They are being removed by the city at a fast clip. If you look up at the city you will notice that many are sick. Its been a concern of mine. I did a little research and this may be the reason. Look up when you are at the city. I think we may be at the end of this stand of oaks.
http://www.nrs.fs.fed.us/4154/focus/decline/
It's not an oak, but I did take a picture of this one when I saw it:
(http://www.weebly.com/uploads/6/0/7/6/6076564/1582199.jpg)