Matt and Elves:

While we were driving on Del Dios Highway, my eight-year-old son could barely maintain himself as he noticed some "bridges" barely visible (to me, anyway, as I tried to concentrate on that lovely yet deceptively treacherous roadway) camouflaged in the hills. I dared to take my eyes off the winding road for a moment to squint into the chaparral, and I did notice bridge-like structures. They appear to be made of wood and resemble small trestles. My best guess, not overwhelmingly approved by my son or my five-year-old daughter, is that they may have carried water pipes or an aqueduct. To increase the "credibility index" with my progeny, can you or the elves (North County branch) help sort this out?

-- kbqhsmith, San Marcos

Okay, Smith Kidlets, it's story time. Shove the elves out of the way and have a seat here in front of the big, sparkly Matthew Alice Fountain of Knowledge (known as the Spigot of Speculation before we redecorated).

Once upon a time, Daddy knew everything. He knew why you had to eat all those icky green things on your plate, and why you couldn't watch the Cartoon Channel all the time, and why you couldn't paint the dog to look like Barney. But one day you noticed that as you're getting taller, Daddy's getting -- oh no! -- dumber! Well, maybe so, but every once in a while he gets one right. Just plain luck, I'd say.

The little pipes and trestles you see on the cliff along the west side of Del Dios Highway is part of the Lake Hodges flume. It carries water from Lake Hodges to the San Dieguito Reservoir in Rancho Santa Fe, about five miles away. Sometimes it goes underground and sometimes it's out in the open. It works without pumps, even though it looks like it runs uphill. (It actually runs downhill.) Tell Dad to siphon some gas out of his gas tank and you'll understand better how the water moves. When people in Rancho Santa Fe and Solana Beach and Encinitas flush their toilets, the water comes from the San Dieguito Reservoir. That's a combination of expensive water from Lake Skinner, very far away, and cheaper water from Lake Hodges. People in Rancho Santa Fe watch how they spend their pennies, so the water district likes Lake Hodges water and has the flume running all the time. It's been running since 1918. That makes it even older than Dad!

If you kids really think the flume is the bomb, well, you better go back and visit it soon. It's about to be replaced by a new system that doesn't hang off the edge of a cliff.