Industrial and municipal loads of BOD5 and TSS estimated as million pounds per year ca. 1995 for the 48 States by Bondelid et al. (2000) for the National Water Pollution Control Assessment Model Version 1.1 (NWPCAM). The primary USEPA data sources used to identify, locate, and estimate annual effluent flow and loading rates of BOD5 and TSS for municipal and industrial point sources were the Permit Compliance System (PCS) and the Clean Water Needs Survey (CWNS) national databases.

The PCS database provides information to characterize pollutant loads from both municipal and industrial wastewater dischargers. PCS defines a wastewater facility as either "major" or "minor," based on the population served (major > 10,000), effluent flow rate (major > 1 mgd), and/or the potential threat to human health or the aquatic environment. PCS further defines the type of wastewater facility using the Standard Industrial Classification (SIC) code for municipal wastewater facilities (SIC = 4952) and industrial facilities (e.g., inorganic chemicals; pulp and paper; iron and steel).

The CWNS database is used by the states and USEPA to track the technical status and needs of municipal wastewater facilities in the United States. The CWNS database provides information about the population served and the level of wastewater treatment for each facility (e.g., primary, secondary, advanced treatment). Data taken from the 1996 Clean Water Needs Survey (USEPA, 1997) were used to characterize municipal wastewater loads ca. 1995.

Industrial Loads The point source inventory compiled by Bondelid et al. (2000) included ~27,000 major and minor industrial facilities. Effluent loads were assigned using composite categories of SIC industrial classifications as compiled by NOAA (1994). Where effluent loading data were not available from the PCS database, typical pollutant concentrations assigned for industrial categories as default values were used to estimate pollutant loads.

Municipal Loads Population served in 1996 (189.7 million) by municipal wastewater treatment plants is based on data obtained from the USEPA 1996 Needs Survey (USEPA, 1997). The municipal point source inventory compiled by Bondelid et al. (2000), using data extracted from the PCS and CWNS databases, included ~ 15,500 municipal facilities. Effluent loads were estimated using either effluent flow and effluent concentration data extracted from PCS for a discharger or the level of wastewater treatment assigned for the discharger in the CWNS database. Where effluent loading data were not available in the PCS database, influent concentrations of 215 mg/L BOD5 and and 215 mg/L TSS were assumed with the following typical removal efficiencies used to estimate the pollutant load of BOD5 and TSS for a discharger:

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