What is this?
This indicator shows the top wastewater dischargers in the Triangle. Wastewater is any water that has been biologically or chemically contaminated by some anthropogenic influence. Most wastewater is treated at wastewater treatment plants where it goes through a multi-step process to remove physical, chemical and biological contaminants. Once treated to the level where it complies with surface water quality regulations developed by the U.S. Environmental Protection Agency and the North Carolina Department of Environment and Natural Resources, it is often discharged into neighboring lakes, rivers or streams.
Why is this important?
Although surface water quality regulations have been developed for many contaminants, there are numerous potentially harmful contaminants for which the U.S. Environmental Protection Agency has not developed safe limits. Known as organic wastewater compounds (OWCs), these classes of unregulated compounds include household, industrial, and agricultural-use compounds, pharmaceutical drugs and antibiotics. A 2007 study conducted by the Triangle Area Water Supply Monitoring Project and the United States Geological Survey, for example, revealed that among the top ten organic wastewater compounds found in eight river and reservoir sites in the Triangle were four known or suspected to disrupt endocrine systems in fish. The study noted that the potential human health effects of many of these compounds are poorly understood and have not been researched. Dischargers are not required to remove unregulated contaminants and thus many of these contaminants have become pervasive in most surface waters.
What does this measure show? In order to discharge to neighboring streams, wastewater treatment plants or private businesses must obtain a National Pollutant Discharge Elimination System (NPDES) permit, which stipulates how much can be discharged as well as the type and amount of allowable pollutants in discharge waters. Discharges from treatment systems with a flow of 1.0 million gallons per day or with a pre-treatment program are classified as major dischargers. There are 22 major dischargers in the Triangle region: 12 wastewater treatment plants, 5 water reclamation facilities, 1 water treatment plant, 2 power plants, and 2 private companies. There are 104 minor dischargers in the study region.
Limitations and Further Research
Although unregulated organic wastewater compounds (OWC) from dischargers are a possible threat to surface water quality, existing water quality standards for known contaminants largely protect streams receiving treated wastewater from wastewater treatment plants. A 1998 study by the Triangle Area Water Supply Monitoring Project and the United States Geological Survey, for example, found as their most significant regionwide water quality trend a decrease in total phosphorus after 1998 that coincided with substantial phosphorus removal measures at many municipal wastewater-treatment facilities in the region. Additionally, the report found that among sites reporting declines or stable amounts of organic nitrogen concentrations were sites receiving wastewater treatment plant effluents (Eno River near Weaver and Knap of Reeds Creek). It should also be noted that concentrations of OWCs detected in the 2007 Triangle Area Water Supply Monitoring Project study were generally within ranges observed at other surface water locations across the U.S. Further research needs to be conducted on the potential human health and environmental impacts of organic wastewater compounds.
Author Brunell Gugelmann, Forestry and Environmental Resources, North Carolina State University :: 2010 April 27 Reviewers Tom Davis, Water Resources Coordinator, Orange County :: Amy Pickle, Duke University Technical Notes
Fresh Water Supply :: Water Use
Water Pollution :: Miles of Impaired Streams :: Riparian Buffers :: Major Dischargers :: Groundwater
Case Studies :: Jordan Lake Rules :: Falls Lake Rules
Major Dischargers
What is this?
This indicator shows the top wastewater dischargers in the Triangle. Wastewater is any water that has been biologically or chemically contaminated by some anthropogenic influence. Most wastewater is treated at wastewater treatment plants where it goes through a multi-step process to remove physical, chemical and biological contaminants. Once treated to the level where it complies with surface water quality regulations developed by the U.S. Environmental Protection Agency and the North Carolina Department of Environment and Natural Resources, it is often discharged into neighboring lakes, rivers or streams.
Why is this important?
Although surface water quality regulations have been developed for many contaminants, there are numerous potentially harmful contaminants for which the U.S. Environmental Protection Agency has not developed safe limits. Known as organic wastewater compounds (OWCs), these classes of unregulated compounds include household, industrial, and agricultural-use compounds, pharmaceutical drugs and antibiotics. A 2007 study conducted by the Triangle Area Water Supply Monitoring Project and the United States Geological Survey, for example, revealed that among the top ten organic wastewater compounds found in eight river and reservoir sites in the Triangle were four known or suspected to disrupt endocrine systems in fish. The study noted that the potential human health effects of many of these compounds are poorly understood and have not been researched. Dischargers are not required to remove unregulated contaminants and thus many of these contaminants have become pervasive in most surface waters.
What does this measure show?
In order to discharge to neighboring streams, wastewater treatment plants or private businesses must obtain a National Pollutant Discharge Elimination System (NPDES) permit, which stipulates how much can be discharged as well as the type and amount of allowable pollutants in discharge waters. Discharges from treatment systems with a flow of 1.0 million gallons per day or with a pre-treatment program are classified as major dischargers. There are 22 major dischargers in the Triangle region: 12 wastewater treatment plants, 5 water reclamation facilities, 1 water treatment plant, 2 power plants, and 2 private companies. There are 104 minor dischargers in the study region.
Limitations and Further Research
Although unregulated organic wastewater compounds (OWC) from dischargers are a possible threat to surface water quality, existing water quality standards for known contaminants largely protect streams receiving treated wastewater from wastewater treatment plants. A 1998 study by the Triangle Area Water Supply Monitoring Project and the United States Geological Survey, for example, found as their most significant regionwide water quality trend a decrease in total phosphorus after 1998 that coincided with substantial phosphorus removal measures at many municipal wastewater-treatment facilities in the region. Additionally, the report found that among sites reporting declines or stable amounts of organic nitrogen concentrations were sites receiving wastewater treatment plant effluents (Eno River near Weaver and Knap of Reeds Creek). It should also be noted that concentrations of OWCs detected in the 2007 Triangle Area Water Supply Monitoring Project study were generally within ranges observed at other surface water locations across the U.S. Further research needs to be conducted on the potential human health and environmental impacts of organic wastewater compounds.
Author Brunell Gugelmann, Forestry and Environmental Resources, North Carolina State University :: 2010 April 27
Reviewers Tom Davis, Water Resources Coordinator, Orange County :: Amy Pickle, Duke University
Technical Notes
Major National Pollutant Discharge Elimination System (NPDES) permit owners were obtained from Appendix VI of the Cape Fear Basinwide Water Quality Plan and Appendix III of the Neuse River Basinwide Water Quality Plan. The Cape Fear Basinwide Water Quality Plan (October 2005) and the Neuse River (July 2009) Basinwide Water Quality Plan are available on the North Carolina Division of Water Quality Basinwide Water Quality Plans website.
Major NPDES Dischargers in the Triangle.xlsx
Water Indicators
Fresh Water Supply :: Water Use
Water Pollution :: Miles of Impaired Streams :: Riparian Buffers :: Major Dischargers :: Groundwater
Case Studies :: Jordan Lake Rules :: Falls Lake Rules