Download data used in the interactive visualization:
Methods and Resources
The following calculations based on measurements by the USGS and Heidelberg University were employed for the interactive visualization:
Total Phosphorus Load (kg P per day) = Discharge (cu. ft per sec) * (28.3168 L per cu. ft) * (86,400 sec per day) * Total Phosphorus Concentration (mg P per L) * (0.000001 kg P per mg P)
Phosphorus Corn-equivalents (bushels corn per day) = Total Phosphorus Load (kg P per day) / (0.06867 kg P per bushel corn)
Phosphorus Fertilizer Dollar-equivalents Wasted (nominal USD per day) = Total Phosphorus Load (kg P per day) * Price of P Fertilizer (nominal USD per Mg P) / (1000 kg P per Mg P)
Data used in the above calculations was sourced as follows:
Discharge (USGS Code = 00060) and Total Phosphorus Concentration (USGS Code = 00665) were obtained from the USGS Water-Quality Data for the Nation portal (http://waterdata.usgs.gov/nwis/qw) and Heidelberg University, National Center for Water Quality Research, Tributary Loading Website (http://www.heidelberg.edu/academiclife/distinctive/ncwqr/data)
The phosphorus content of corn was estimated based on the USDA Crop Nutrient Tool (http://plants.usda.gov/npk/main)
The Price of P Fertilizer (for each year) was estimated based on data from the National Agricultural Statistics Service, USDA (P price derived from DAP price, assuming that DAP is 46% phosphate and that phosphate is 43.64% P).
For the USGS 2002 SPARROW data layers (Robertson and Saad 2011) shown in the interactive visualization as shades of blue:
- Total Phosphorus Load (kg P per yr)
- The mean annual phosphorus load leaving each stream reach, as predicted by the USGS 2002 SPARROW model. The load reflects the accumulated mass of phosphorus contributed by all sources in the total drainage area upstream of the reach outlet. The load includes the effects of in-stream attenuation processes in all upstream reaches. Loads from individual sources leaving each stream reach estimated by the USGS 2002 SPARROW model are also viewable.
- Phosphorus Corn-equivalents Wasted (bushels of corn per yr)
- The mean annual load of phosphorus corn-equivalents leaving each stream reach. This value represents the amount of corn that theoretically could have been harvested containing the Total Phosphorus Load. We calculated these values using the 2002 SPARROW model output and the conversions shown above.
- Phosphorus Fertilizer Dollar-equivalents Wasted (2002 USD per yr)
- The mean annual load of phosphorus fertilizer dollar-equivalents leaving each stream reach. This value represents the theoretical economic value of the Total Phosphorus Load in terms of fertilizer. We calculated these values using the 2002 SPARROW model output and the conversions shown above.
For near-continuous daily datasets of Flow and Total Phosphorus concentration data for the Maumee, Sandusky, and Cuyahoga watersheds, missing data points were estimated using linear interpolation.
In the video, we state the following: “Each year, the amount of phosphorus entering the lake and contributing to toxic cyanobacteria blooms could have instead been harvested in around 100 million of bushels of corn. This lost phosphorus is also equivalent to commercial fertilizer worth approximately 10-30 million dollars per year.” These estimates were determined as follows: We examined recent (2000-2011) variability in annual total phosphorus loading to Lake Erie as estimated in the 2013 Ohio Lake Erie Phosphorus Task Force II Final Report. The values ranged from around 5,000 Mg P per year to around 11,000 Mg P per year. Total P loads were converted to corn-equivalents and fertilizer equivalents using the conversions shown above for each year. The results presented in the video are not exact, but represent the typical approximate magnitude of each resource equivalent embodied in P lost to Lake Erie.
The Percent Frequency of Detectable Cyanobacteria images shown in the video are from Wynne and Stumpf (2015).
Information on the most recent algal blooms presented in the first few sections of the video are from Wines (2013) and Fitzsimmons (2014).
Additional information in the video on Lake Erie trends is from Conroy et al. (2005) and the Ohio Lake Erie Phosphorus Task Force II Final Report (2013). More information on "legacy phosphorus" can be found in Sharpley et al. (2013).
Here, data from the USGS and Heidelberg University are visualized. More Lake Erie basin data are available from other organizations. The following 17 organizations have engaged in water quality monitoring in the region (Betanzo et al. 2015):
- Ohio Environmental Protection Agency
- U.S. Geological Survey, National Water Information System
- Indiana Department of Environmental Management
- Michigan Department of Environmental Quality
- Pennsylvania Fish and Boat Commission
- Northeast Ohio Regional Sewer District
- Saint Joseph River Watershed Initiative
- U.S. National Park Service
- Hoosier Riverwatch
- U.S. Department of Energy
- University of Michigan-Ann Arbor (Dr. Nathan Bosch)
- New York Department of Environmental Conservation
- Heidelberg University, National Center for Water Quality Research
- U.S. Environmental Protection Agency
- Pennsylvania Department of Environmental Protection
- National Oceanic and Atmospheric Administration, National Estuarine Research Reserve System
- U.S. Department of Agriculture, Agricultural Research Service
Betanzo, E.A., Choquette, A.F., Reckhow, K.H., Hayes, L., Hagen, E.R., Argue, D.M., and Cangelosi, A.A. 2015. Water data to answer urgent water policy questions: Monitoring design, available data and filling data gaps for determining the effectiveness of agricultural management practices for reducing tributary nutrient loads to Lake Erie, Northeast-Midwest Institute Report, 169 p., http://www.nemw.org/.
Conroy, J.D., et al. 2005. Temporal trends in Lake Erie plankton biomass: roles of external phosphorus loading and dreissenid mussels. Journal of Great Lakes Research 31: 89-110.
Fitzsimmons, E.G. “Tap Water Ban for Toledo Residents.” NY Times. Aug 3, 2014.
“Ohio Lake Erie Phosphorus Task Force II Final Report.” Ohio Department of Agriculture, Ohio Department of Natural Resources, Ohio Environmental Protection Agency, and Ohio Lake Erie Commission. November 2013.
Robertson, Dale M. and David A. Saad, 2011. Nutrient Inputs to the Laurentian Great Lakes by Source and Watershed Estimated Using SPARROW Watershed Models. Journal of the American Water Resources Association 47(5):1011-1033.
Sharpley, A.N., et al. 2013. Phosphorus legacy: overcoming the effects of past management practices to mitigate future water quality impairment. Journal of Environmental Quality 42: 1308-1326.
Wines, M. “Spring Rain, Then Foul Algae in Ailing Lake Erie.” NY Times. March 14, 2013.
Wynne, T.T., and R.P. Stumpf. 2015. Spatial and temporal patterns in the seasonal distribution of toxic cyanobacteria in western Lake Erie from 2002-2014. Toxins 7: 1649-1663.
GIS Basemap Sources
Esri, DeLorme, GEBCO, NOAA NGDC, and other contributors
Esri, DigitalGlobe, GeoEye, i-cubed, USDA, USGS, AEX, Getmapping, Aerogrid, IGN, IGP, swisstopo, and the GIS User Community
- Algal bloom aerial:
- NASA image by Jeff Schmaltz
GIS Movie Sources
- Rivers and streams:
- HydroSHEDS _RIV_ _ River network _stream lines_ at 15s resolution _ North America
- Ag / urban landcover:
- UN Cartographic Section, National Mapping Organizations (GLCNMO)
- Video Soundtrack:
- "Light Bearer" from 11.11 vol 1 by Ketsa. Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.
- Video Voice-over
- Catherine LeClair