The "Lake Project" is an art on billboards exhibition. A number of photos of Owens Lake, in southern California are put up on billboards in the San Francisco Bay Area. Owens Lake is an environmental disaster caused by overdrainage to quench the ceaseless thirst of Los Angeles. This site has images from the billboards in a flash animation and a number of links to information about Owens Lake.
dead link: http://www.lakeproject.org/