Thank you for this forum Dave, I didn't know where I was going to post this!
I came across this link in a garden magazine and it is such an important subject I wanted to pass it along. It deals with reducing runoff to sewers by building rain gardens that catch the water before it has a chance to "run off!" This is a Connecticut publication, but applicable anywhere. Very simple and inexpensive to do, but they can have such an impact if the word spreads.
Without knowing this, my DH is digging a ditch today to redirect our runoff to some large pine trees that only get watered when it rains. This will accomplish the same thing, really. The trees will get directly watered in the rainy season, and benefit from the occasional runoff in the dry months - we have a short rain season here and it's been really dry this year.