This dam was built by Spanish missionaries and local
native Americans between 1813-1816 in San Diego, CA.
It is now an almost forgotten corner of the Mission
Trails Regional Park. It still does its job -- there's
water there, even though it hasn't rained here in 180
days. (This water, however, is no longer used for drinking
or any other purpose.)

My alternative PaD is here: http://www.pbase.com/digitalgee/image/35067918

If you want to learn more about the park, click here: http://www.mtrp.org/