California's Matilija Dam is a huge mistake. Over 60 years after its construction, engineers and ecologists are realizing it does more harm than good—a feeling shared by the rogue artists who painted huge, easy instructions as a fix.
I'm not sure what the proper protocol is for removing a dam without causing an instant flood, but it's probably a little more complicated than splitting it down the middle. Still, the work's been a hit with locals. Even the county public works director wants the graffiti to stay: "Everyone I've talked to has really enjoyed it. It sends a good message." [LA Times]
Image credit Mel Melcon, Los Angeles Times / September 19, 2011