Wastewater Outfalls

publication date

Marine Cadastre Data Registry

npdes_dmrs_fy2021.zip

Original source data

Active facilities are those currently in operation. Major/federally-reportable are facilities for which states must submit compliance and enforcement data to EPA. Under the Clean Water Act, a major facility is any NPDES facility or activity classified as such by the regional administrator, or in the case of approved state programs, the regional administrator in conjunction with the state director. Major municipal dischargers include all facilities with design flows of greater than one million gallons per day and facilities with EPA/state approved industrial pretreatment programs. Major industrial facilities are determined based on specific ratings criteria developed by EPA/state. Minor/not federally-reportable are facilities for which states are not required to submit data to EPA. EPA is therefore not able to verify the accuracy or comparability of data for these permits, although the Agency tracks their names and locations and may have some data about their inspections and enforcement activity.

Original source data

Geospatial dataset of facilities containing positional information (latitude and longitude values) regulated by ICIS-NPDES that is maintained and updated monthly by the Facility Registry Service (FRS). The National Pollutant Discharge Elimination System (NPDES) module of the Integrated Compliance Information System (ICIS). Under NPDES, all facilities that discharge pollutants from any point source into waters of the United States are required to obtain a permit. The permit will likely contain limits on what can be discharged, impose monitoring and reporting requirements, and include other provisions to ensure that the discharge does not adversely affect water quality.

Data was downloaded for all US waters and included the following layers that contain pipeline information possibly relevant to wastewater outfall pipes: 1) "Approach_Pipeline_Submarine_on_land_line", and 2) "Overview_Pipeline_Submarine_on_land_line"

These were used as a baseline for mapping outfall pipe locations and were updated or added to during the subsequent build process

Discharge point data. Used primarily as a reference layer to confirm facility locations and outfall locations. The final outfall features were not created from this layer directly as this data often included many point features per facility, and the locations for outfalls often did not represent the actual in water discharge point.

Wastewater facility feature

This dataset was used to help define what inland waterways should be included when considering coastal wastewater outfalls.

Subject matter experts from the NOAA National Centers for Coastal Ocean Science, and the NOAA Office for Coastal Management conducted two pilot studies to evaluate data sources and to inform the design of the proposed data product. These pilots were shared with peers to elicit input on the final data product design.

Outfall Pipes: All data source that could contain a pipeline feature were reviewed, pipeline feature were aggregated, cleaned and flagged with a unique identifier (PGM_SYS_ID) of the coincident facility. Pipeline positions were verified when visible in orthoimagery. Visually verifiable features were retained and superseded any record originating from the ENC and RNC sources. Any ENC or RNC feature that exhibited a break, edge of data offset, or duplicate was edited manually in ArcGIS to repair or remove the error.

Facilities: Through visual inspection, facilities were removed from the source data if they were outside of the vicinity of the coast and the immediate navigable waterways. Duplicate facility records were removed. Facilities that could not be defined as Publicly Owned Treatment Works, or as another significant contributor were removed. Facility locations were adjusted when their location was clearly in error.

Outfall: For each facility an attempt was made to identify the primary outfall location if it discharged into surface waters. Source data for an outfall location included examples such as; EPA FRS records, permits, NOAA RNC, and the end of an outfall pipeline. Generally only one outfall was mapped per facility. Each outfall point feature was flagged with an identifier (PGM_SYS_ID) that links it to the relevant facility and pipe.

Quality control testing for completeness, accuracy, and representativeness was conducted by personnel not directly involved in the hands-on development and editing of the data.

An update was made to the MWRA outfall pipe location and the MWRA outfall location with the EPA FRS Registry Identifier = 110025247720. The source of the update was Raster Nautical Chart 13270, Edition 66, 2018-12-01, compiled at a scale ratio of 1 to 25,000. This supersedes the previous record which was sourced from Raster Nautical Chart 13267, Edition 37, 2019-09-01, compiled at a scale ratio of 1 to 80,000.