Beaver Dams

There are pros and cons of Beaver Dams.

http://i801.photobucket.com/albums/y...s/dd155af3.jpg
Do they block spawn movement?
http://i801.photobucket.com/albums/y...s/54363ae2.jpg
Does you Trout Of A Lifetime live here?
http://i801.photobucket.com/albums/y...s/4b106ed0.jpg
Do long term dams make water temps go up and ruin the ph?
http://i801.photobucket.com/albums/y...s/59881211.jpg
Do you get fired up when you see a dam?
http://i801.photobucket.com/albums/y...s/e675843b.jpg
Have you ever had 2 outings at a beaver dam where both times you scored over 100 trout?

What do you think of them?