Wellhead Protection
http://www.epa.gov/safewater/whpnp.html

I am drawing a lot from the one I am most familiar with
http://www.iowadnr.com/water/iwp/index.html

Karst
http://en.wikipedia.org/wiki/Karst

http://www.karstwaters.org/

Edwards Aquifer
http://www.edwardsaquifer.net/

http://edwardsaquifer.org/

http://www.bseacd.org/