Satellite Monitoring of Algal Blooms in Idaho Waterbodies Active
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 datasets are related to this study.
Chlorophyll-a concentrations and algal bloom condition paired with Sentinel-2 aquatic reflectance values collected for Brownlee Reservoir, ID from 2015 through 2020
The following publications are associated with this study.
Mapping the probability of freshwater algal blooms with various spectral indices and sources of training data
The following web tools are associated with this study.
REmote Aquatic Chlorophyll-a Tracker (REACT)
This tool shows the presence of aquatic chlorophyll-a in select waterbodies. Note: This tool indicates the presence of aquatic chlorophyll-a and should not be used to determine if a toxic cyanobacterial bloom (harmful algal bloom) is present.
The following news stories are associated with this study.
We thank these partners for their support.
- Overview
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)
- Science
The following other science projects are associated with this study.
Harmful Algal Bloom (HAB) Cooperative Matching Funds Projects
New projects from coast to coast will advance the research on harmful algal blooms (HABs) in lakes, reservoirs and rivers. The vivid emerald-colored algal blooms are caused by cyanobacteria, which can produce cyanotoxins that threaten human health and aquatic ecosystems and can cause major economic damage. - Data
The following datasets are related to this study.
Chlorophyll-a concentrations and algal bloom condition paired with Sentinel-2 aquatic reflectance values collected for Brownlee Reservoir, ID from 2015 through 2020
This data release presents two calibration datasets that relate aquatic reflectance derived from Sentinel-2 satellite imagery with algal bloom conditions in the Brownlee Reservoir on the Idaho Oregon border. These datasets were developed to evaluate remote sensing methods for identifying algal blooms in Brownlee Reservoir like those from July 2022 that are illustrated in field photo (left) and sat - Publications
The following publications are associated with this study.
Mapping the probability of freshwater algal blooms with various spectral indices and sources of training data
Algal blooms are pervasive in many freshwater environments and can pose risks to the health and safety of humans and other organisms. However, monitoring and tracking of potentially harmful blooms often relies on in-person observations by the public. Remote sensing has proven useful in augmenting in situ observations of algal concentration, but many hurdles hinder efficient application by end userAuthorsTyler Victor King, Stephen Hundt, Konrad Hafen, Victoria G. Stengel, Scott D. Ducar - Web Tools
The following web tools are associated with this study.
REmote Aquatic Chlorophyll-a Tracker (REACT)
This tool shows the presence of aquatic chlorophyll-a in select waterbodies. Note: This tool indicates the presence of aquatic chlorophyll-a and should not be used to determine if a toxic cyanobacterial bloom (harmful algal bloom) is present.
- News
The following news stories are associated with this study.
- Partners
We thank these partners for their support.