In our increasingly digital world, students are often disconnected from the natural environment and may not understand how human actions affect it. One of the most significant human impacts on ecosystems is water pollution. Measuring the water quality of a local stream, river, or lake can be a valuable learning experience but is often impractical. Many schools lack a nearby body of water or a sufficient budget for field trips. The investigation described in this article introduces students to major water pollutants and how each can impact an aquatic ecosystem--without necessarily having to visit a body of water. This activity involves a pretend town, Waterton, which has a river running through it and emptying into the nearby Gulf of Mexico. The river carries pollutants to a Gulf estuary where sea grass provides habitat for seahorses. Students research the components of the seahorses' ecosystem and food web and in the process learn to care about the effects of water pollution. Thus, the seahorses are the lesson's "hook." This lesson was designed for an environmental science elective but also would be appropriate for a biology class studying ecology or an Earth science class studying water and watersheds.