Monitoring algal blooms in drinking water reservoirs using the Landsat-8 Operational Land Imager

ABSTRACT

In this study, we demonstrated that the Landsat-8 Operational Land Imager (OLI) sensor is a powerful tool that can provide periodic and system-wide information on the condition of drinking water reservoirs. The OLI is a multispectral radiometer (30 m spatial resolution) that allows ecosystem observations at spatial and temporal scales that allow the environmental community and water managers another means to monitor changes in water quality not feasible with field-based monitoring. Using the provisional Land Surface Reflectance product and field-collected chlorophyll-a (chl-a) concentrations from drinking water monitoring programs in North Carolina and Rhode Island, we compared five established approaches for estimating chl-a concentrations using spectral data. We found that using the three band reflectance approach with a combination of OLI spectral bands 1, 3, and 5 produced the most promising results for accurately estimating chl-a concentrations in lakes (R² value of 0.66; root mean square error value of 8.9 µg l⁻¹). Using this model, we forecast the spatial and temporal variability of chl-a for Jordan Lake, a recreational and drinking water source in piedmont North Carolina and several small ponds that supply drinking water in southeastern Rhode Island.

KEYWORDS:

• Landsat-8
• chlorophyll-a
• water quality
• monitoring

Acknowledgments

The authors thank K. DeVilbiss (NCDEQ DWR); M. Hale (NCDEQ DWR); J. Smith (NCDEQ DWR); E. Morris (NCDEQ DWR); and D. Owen (NCDEQ DWR) for Jordan Lake sampling. They also thank R. Lunetta (USEPA), B. Schaeffer (USEPA), W. Salls (ORISE Fellow), A. Kuhn-Hines (USEPA) and J. LiVolsi (USEPA) for their insightful and valuable review comments.

Disclosure statement

This article is distributed solely for the purpose of pre-dissemination peer review under applicable information quality guidelines. It has not been formally disseminated by the US EPA. It does not represent and should not be construed to represent any Agency determination or policy.

Mention of trade names, products, or services does not convey, and should not be interpreted as conveying, official EPA approval, endorsement, or recommendation. The views expressed in this article are those of the authors and do not necessarily reflect the views or policies of the U.S. Environmental Protection Agency.

Additional information

Funding

This work was supported by the NASA Ocean Biology and Biogeochemistry Program/Applied Sciences Program under proposal 14-SMDUNSOL14- 0001 and by EPA, NOAA, and USGS Toxic Substances Hydrology Program. This work was also supported by the U.S. Environmental Protection Agency Office of Research and Development and the Safe and Sustainable Waters Resources Program.