The lake in the picture below is San Luis Reservoir near Santa Nella.
The lake in the picture below is Castaic Lake in Southern California (picture from the commons at Wikipedia). It fills a canyon region in the western San Gabriel Mountains near I-5 above the Santa Clarita Valley.OK, so here is my observation: Picture #1 is to picture #2 as picture #3 is to picture #4, but on a different scale of magnitude (magnitude of what? Not stated here!). Any ideas?