Satellite Monitoring of Algal Blooms in Idaho Waterbodies
Harmful algal blooms (HABs) are an increasing concern in Idaho. Within the past few years, Idaho agencies have issued at least 57 HAB notices on 29 waterbodies throughout the state. Toxins produced by HABs pose risks to human and animal health. Local economies may also be adversely affected when algal blooms discourage outdoor recreation.
Routinely monitoring the state's many waterbodies is too expensive to be practical. As a result, state agencies and health districts are often forced to respond to citizen reports to send field crews out to collect water samples. Earth observation satellites can guide more proactive field monitoring by capturing multispectral images of entire waterbodies with a frequency of greater than one capture per week. These images will help agencies to know when and where to collect water samples for testing.
In collaboration with Idaho Power Company, the Idaho Department of Water Resources, and the Idaho Department of Environmental Quality, we produce automated software tools to map aquatic chlorophyll, a common pigment present in algal blooms, from multispectral satellite imagery collected by the Sentinel-2 fleet (European Space Agency). Maps of aquatic chlorophyll conditions are produced approximately once per week for 24 Idaho water bodies and delivered through the REmote Aquatic Chlorophyll Tracker (REACT). Maps are created using an aquatic chlorophyll classification model (King and others, 2022) trained on observations from Brownlee Reservoir on the Oregon-Idaho border (King and Hafen, 2022). The classification model maps probability that chlorophyll-a concentrations exceed 10 micrograms per liter of chlorophyll.
In addition to the calibrated chlorophyll classification map for two-dozen water bodies, the REACT web-application also provides uncalibrated remote sensing indicators of water clarity and aquatic chlorophyll for any pixel identified as water in the Sentinel-2 satellite imagery from 2019 to present. These uncalibrated products, known as spectral indices, can be used to perform relative comparisons in remotely sensed water quality between waterbodies and overtime.
Read our 2022 information sheet USGS Science to Protect Wildlife and Human Health (PDF)
The following other science projects are associated with this study.
Harmful Algal Bloom (HAB) Cooperative Matching Funds Projects
The following other science projects are associated with this study.