> I live in Washington, though, and we sure have a lot of man-made storage ponds.
I can think of some spots where four or five adjacent suburban developments will all have their own pond/catchment tucked away, although their appearance and attractiveness varies.
I'm out duck hunting right now and there's quite a lot of very very damp farmland in the Seattle/Tacoma/Everett metroplex. The river valley behind microsoft would be idiotic to build anything bu farms and golf courses on (and the golf course is unplayable half the year). The term colloidal substance describes these areas well. Also a ton of water retention areas on the hills, otherwise stuff would wash out very easily.