WaterQual
Sentinel-2 water quality monitoring for lakes, reservoirs, and other inland/coastal waterbodies — chlorophyll-a and turbidity proxies (NDCI, NDTI) plus calibrated chlorophyll-a estimators (OC3, Gilerson), no account or API key required.
Searches Microsoft Planetary Computer for the least-cloudy Sentinel-2 L2A scene over a waterbody and date you choose, masks clouds/shadows and non-water pixels, and computes one of four water-quality algorithms: NDCI (unitless chlorophyll-a proxy), NDTI (unitless turbidity proxy), OC3 (calibrated chlorophyll-a for clear water), or Gilerson (calibrated chlorophyll-a for turbid water). Works on lakes, reservoirs, ponds, and other water surfaces large enough for a stable sample at Sentinel-2's 10m resolution. Saves a georeferenced index GeoTIFF plus a report with summary statistics, and can optionally also save the raw RGB+NIR+SWIR imagery alongside it for visual monitoring. No sign-in or API key needed — Sentinel-2 is in Planetary Computer's open, public collection tier.