Lake Tahoe has become a symbol of the controversial balance between preserving and expanding into natural systems. Tahoe’s clarity has also been decreasing since at least 1968; down from 100 feet of visibility to about 70 feet nowadays. Fine particles from urban expansion is one of the main causes, as well as the introduction of invasive species. These photos and questions will help students to understand some of the reasons why Tahoe is becoming murkier. They can provoke relevant ideas about how to slow that loss of clarity down or even reverse it, so that future generations of people and native species can enjoy and rely on this magnificent lake, just as we have done in the past. Simply click the paperclip in each image to see the prompts pertaining to each photo. This collection is ideal for a discussion-based lesson.