The discharge data base contains estimates of the amount of nutrients
entering Chesapeake Bay waters from both point and nonpoint sources.
It also contains some estimates of toxic chemical loadings to Bay
waters from municipal and industrial dischargers. National and regional
EPA files were merged to create the point source discharge data base.
These included the 1980 NEEDS Survey, the Industrial Discharge File,
the Management Information Control System, the Permit Compliance System,
and the National Enforcement Information Center data base. Data elements
included are nutrients, heavy metals, and flow data. In addition,
information related to location including county, state, and administrative
identifiers such as NPDES number and activity type is available. Hydrologic
information identifiers include basin, receiving stream, sub-basin,
and an indication if above or below the fall line. The geographic
coverage is for the entire Chesapeake Bay drainage basin. This data
base was used to estimate both nutrient and toxic loadings into the
Bay. Nutrient loadings were used in the Chesapeake watershed modeling
efforts, the VIMS modeling efforts and the NVPDC models. The period
of record is 1980, however, some nutrient load estimates were made
for 1970.