UAS footage captured during harmful algal blooms (HABs) mapping campaign over Williams Fork and Willow Creek Reservoirs in Grand County, CO

Harmful algal blooms (HABs) caused by cyanobacteria have become an ongoing concern in Colorado reservoirs, including Williams Fork and Willow Creek Reservoirs, where blooms have led to recreational closures and can pose risks to people, pets, livestock, and wildlife. To improve HAB monitoring, researchers are exploring high-resolution uncrewed aircraft system (UAS) data, including hyperspectral imagery potentially capable of distinguishing algal species and pigments at spatial and temporal scales not achievable with traditional boat-based or satellite observations alone.

In August 2026, the USGS National Uncrewed Systems Office collected hyperspectral UAS data in support of HAB and water-quality studies led by the Colorado Water Science Center and Hydrologic Remote Sensing Branch. Aquatic drones were deployed to measure algal fluorescence and other water-quality parameters through surface transects and vertical profiles, while boat-based sampling provided water-column measurements and samples for nutrient analysis, phytoplankton identification, and cyanobacteria toxin and gene testing.

The scientific UAS flights were conducted with authorization from Denver Water, Northern Water, and the U.S. Forest Service.

Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.