SwimZone Water Quality Dataset (13,126 US lakes and beaches)

Location-level swim-safety data for 13,126 lakes and beaches across the United States, combining satellite cyanobacteria monitoring and beach bacteria advisories into a single plain-language verdict for each water body. This is the open snapshot behind SwimZone, a free daily swim-safety check for lakes and beaches. See the methodology for how each water is scored. Source repository: github.com/Nathanzo/swimzone-data. Sources: EPA Cyanobacteria Assessment Network (CyAN) satellite imagery and EPA BEACON / state beach-monitoring programs (public domain). The verdict bands are SwimZone's own synthesis. Snapshot date 2026-07-18.