RAY: Here's the answer. Upstream there are trees that take carbon dioxide from the air and make oxygen out of it. That greenery is using up water to make leaves and do that process of photosynthesis.
Well, by the time November rolls around, the trees and all the other shrubs that are growing by the stream have begun to go into dormancy. The leaves change color, they fall off the trees, and the need for water diminishes considerably so they're not sucking water out of the stream. Then, even though there's no rain--the level what?
TOM: Goes up.
RAY: There you go. Do we have a winner?
TOM: Yes. The winner is Susan Cady from Morrison, Missouri. And for having her answer selected at random from among all the correct answers that we got, Susan's going to get a $26 gift certificate to the Shameless Commerce Division at cartalk.com, with which she can get something for her father for Father's Day.
RAY: Yeah, and you know if your father's kind of a pain in the butt, you can get him a copy of our CD, Why You Should Never Listen to Your Father When It Comes to Cars. Once he gets that he might ignore you for weeks. Congratulations, Susan!
[ Car Talk Puzzler ]