At coastal archaeological sites, measuring erosion rates and assessing artifact loss are vital to understanding the timescale(s) and spatial magnitude of past and future site loss. We describe a straightforward low-tech methodology for documenting shoreline erosion developed by professionals and volunteers over seven years at Calusa Island Midden (8LL45), one of the few remaining sites with an Archaic component in the Pine Island Sound region of coastal Southwest Florida. We outline the evolution of the methodology since its launch in 2016 and describe issues encountered and solutions implemented. We also describe the use of the data to guide archaeological research and document the impacts of major storms at the site. The response to Hurricane Ian in 2022 is one example of how simply collected data can inform site management. This methodology can be implemented easily at other coastal sites at low cost and in collaboration with communities, volunteers, and heritage site managers.