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METHODOLOGY TO ESTABLISH WATER QUALITY PARAMETERS ON THE U.S. COUNTY LEVEL
Citation:
JAGAI, J. S., B. J. Rosenbaum, S. M. Pierson, L. C. Messer, K. Rappazzo, AND D. T. LOBDELL. METHODOLOGY TO ESTABLISH WATER QUALITY PARAMETERS ON THE U.S. COUNTY LEVEL. Presented at Water and Health: Where Science Meets Policy, Chapel Hill, NC, October 03 - 07, 2011.
Impact/Purpose:
We are a developing a county-level environmental quality index (EQI) for the US, including variables representing four domains previously associated with human health (air, water, land, and built/social environment) encompassing the years 2000-2005. This index will be used to explore the relationship between simultaneous environmental impacts and human health. Water quality parameters will be included within the water domain of this index. However, it is necessary to have a consistent methodology to establish water quality parameters on the county level. We report on the methodology incorporating this monitoring data to establish turbidity measures at the county level for the entire country.
Description:
The United States Geological Survey (USGS) collects water quality data at approximately 1.5 million sites in the United States (US) for both surface water and ground water locations. These data are provided publicly through the National Water Information System (NWIS) web interface. The data include water quality parameters such as temperature, specific conductance, turbidity, nutrients, and volatile organic compounds. These data are typically used for location specific analyses. However, the data are potentially useful for larger national level analysis. We are a developing a county-level environmental quality index (EQI) for the US, including variables representing four domains previously associated with human health (air, water, land, and built/social environment) encompassing the years 2000-2005. This index will be used to explore the relationship between simultaneous environmental impacts and human health. Water quality parameters will be included within the water domain of this index. However, it is necessary to have a consistent methodology to establish water quality parameters on the county level. We report on the methodology incorporating this monitoring data to establish turbidity measures at the county level for the entire country. We obtained data for the years 2000-2005 for all samples containing turbidity values (93,754 samples), from sites in the US (9615 sites). All states contained sampling sites, with the fewest number of samples in Rhode Island (26 samples from 10 sites) and the largest number of samples in Georgia (25,608 samples from 792 sites). As an example of the extent of the data, turbidity data was available for 92 counties of the 98 counties in the state of Iowa for the time period 2000 through 2005. The highest turbidity level (measured at 4200 NTU) was reported in Fremont County, IA at one sample site. The lowest turbidity level (0.1 NTU) was reported in four counties from four individual sample sites (one per county). Of the 3141 counties in the US, 1344 counties had sample sites with recorded data. Data will be interpolated for the remaining counties. This methodology will be used to calculate county level estimates for the entire country for other water quality parameters from the NWIS system including total sediment discharge, chlorophyll, total nitrogen, nitrate, phosphorus, and ammonia. Utilizing previously collected data to develop national level estimates for water quality parameters allows us to represent water quality when developing a national scale environmental quality index. Water quality is not consistently measured, spatially or temporally, for the entire country; therefore, without implementing these types of interpolation methodologies, water quality parameters cannot be incorporated in national level environmental quality analyses. This abstract does not necessarily reflect EPA policy.