Trends in instream total nitrogen and total phosphorus upstream and downstream of wastewater facilities in Georgia Level III Ecoregions, 1967 – 2010
Behrend, Glen R.
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Using the Georgia Water Resources Database (WRDB), analysis was conducted of instream Total Nitrogen and Total Phosphorus trends at water quality sampling sites in each Level III Ecoregion of Georgia. Over 71,000 individual samples from 1967 - 2010 were analyzed. Each sample station was cataloged using GIS coverages as being either upstream or downstream of a permitted wastewater discharge or land application systems (LAS). Generally, over the period of record, sites downstream of permitted wastewater facilities show higher Total Phosphorus statewide. Total Nitrogen values are split between north Georgia (Ecoregions 68, 67, 66, and 45) and south Georgia (Ecoregions 75 and 65). In north Georgia, Total Nitrogen appears to be greater in downstream sites, whereas the trend is unclear in south Georgia. Decadal trends for each Ecoregion were also analyzed. Generally a declining trend was observed for Total Phospohrus, whereas Total Nitrogen was flat or increasing.