Water Pollution Search Results Help - DMR

The Search Results page presents results that meet the search criteria specified on the Search page. The search criteria you entered will be listed across the top of the page in blue ovals. Select the "X" next to a criteria to remove it and modify the results. The "modify search" will also allow you to change the search criteria. The "new search" button will reset all specified criteria.

Note that a value marked with a  Outlier Flag blue flag indicates that the value contains loads calculated using DMR data that has been flagged as potential outliers or data errors. A value marked with a  Load Over Limit Flag yellow flag indicates that there was one or more exceedances of permit effluent limits for the pollutant sometime during the year. Hovering over the yellow flag allows a user to see the load over limit value. 

Click on the links below to quickly find the table of interest.


Search Statistics - Facility Counts

This table provides information about the scope of the facilities included in your search results. Statistics include the total number of NPDES permits that are included in the search results, the number of permits that have monitoring data, and the number of permits that have discharge limits.

Note that the facility counts and summary tables below do not include pollutants for which annual loadings cannot be calculated, such as temperature and pathogen indicators. Run a separate search for these pollutant categories. Definitions for table column headings can be found in DMR Search Statistics Help.


Top Pollutants by Pounds (year)

For a given year this chart lists the top ten pollutants by name and the total pounds released in lbs/yr. The pollutants are ranked in order of decreasing mass. When available, select the pollutant name to view the EPA Substance Registry Services (SRS) chemical information. For a complete list of pollutants, select the "Download All Data" button.


Top Pollutants by Toxic-Weighted Pounds (TWPE) (year)

For a given year this chart lists the top ten pollutants by name and their total TWPE lbs-eq/yr. The pollutants are ranked in order of decreasing toxic-weighted pound equivalents (TWPE).

EPA calculates TWPE in a given year using DMR data and pollutant specific toxic weighting factors (TWFs) in order to rank the relative toxicities of different pollutant discharges. Pollutants have different toxicities to human health and aquatic communities and the TWPE unit provides a relative measure of how the potential toxic nature of one pollutant compares against another pollutant.

For some pollutants you can select the name to obtain more information about it. For a complete list of all pollutants select the "Download All Data" button. Select the "Compare to TRI" button to link to a single chart that provides both DMR and TRI data as well as the percentage difference between them.

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Top Receiving Watersheds

The Loading Tool only displays this table if you specify a pollutant or pollutant category in your search. This table lists the ten watersheds that receive the largest discharges of the pollutant specified in your search. Each table ranks the watershed loads as follows:

  • Pollutants with Toxic Weighting Factors: Ranks watershed loads by decreasing toxic-weighted pound equivalents.
  • Pollutants with no Toxic Weighting Factors (e.g., Biochemical Oxygen Demand): Ranks watershed loads by decreasing pollutant mass.
  • Pathogen Indicators: Ranks watersheds by decreasing maximum concentration (count per 100 mL).
  • Temperature: Ranks watersheds by decreasing maximum temperature (°F).
  • Wastewater Flow: Ranks watersheds by decreasing annual wastewater volume (millions of gallons per year). Note the Loading Tool does not display this table if you enter search criteria for Location/Watershed.
HUC-12 Code
Hydrologic Unit Code (HUC) code assigned by the US Geological Survey used to classify watersheds in the United States and the Caribbean. Code consists of two to twelve digits based on six levels of classification: Region (first-level, 2-digit HUC), Subregion (second-level, 4-digit HUC), Accounting unit (third-level, 6-digit HUC), Cataloguing unit (fourth-level, 8-digit HUC), Watershed (fifth-level, 10-digit HUC), and Subwatershed (sixth-level, 12-digit HUC).
The Watershed Boundary Dataset does not include HUC-12's for all NPDES permits in ICIS-NPDES. As a result the HUC-12 can be blank for some facilities in the Loading Tool database. However, the Water Pollution Search does not display results for facilities with blank HUC-12 codes in this table.
HUC Name
The name that corresponds to the HUC-12 Code. It is usually the name for the most significant body of water in the subwatershed.
Avg Concentration (mg/L)
The average of the average monitoring period concentrations in a reporting year. For example, if a facility reports monthly average discharge concentrations, the annual average facility concentration is the arithmetic average of the reported monthly average concentrations. For each HUC-12, this table presents the average of the annual average facility concentrations. Note the Loading Tool does not display this column if you select Pathogen Indicators, Temperature, or Wastewater Flow for your search.
Pollutant measurements can be stored in ICIS-NPDES as mass quantities or concentrations. If the measurement of interest is a mass quantity, then the Loading Tool will back-calculate the average concentration using the mass quantity and wastewater flow. However, if the Loading Tool cannot identify a wastewater flow for this calculation, then it will display zero for the average concentration.
Avg Conc (count/100mL)
The average of the average monitoring period pathogen concentrations in a reporting year. For example, if a facility reports monthly average pathogen concentrations, the annual average facility concentration is the arithmetic average of the reported monthly average concentrations. For each HUC-12, this table presents the average of the annual average facility concentrations. Note the Loading Tool only displays this column if you search on Pathogen Indicators.
This table does not display results that have an average concentration of zero.
Average (°F)
The average of the average monitoring period wastewater temperatures in a reporting year. For example, if a facility reports monthly average temperatures, the annual average facility temperature is the arithmetic average of the reported monthly average temperatures. For each HUC-12, this table presents the average of the annual average facility temperatures. Note the Loading Tool only displays this column if you search on Temperature.
This table does not display results that have an average temperature of zero.
Max Concentration (mg/L)
The maximum of the average monitoring period concentrations in a reporting year. For example, if a facility reports monthly average discharge concentrations, the maximum facility concentration is the maximum of the reported monthly average concentrations. For each HUC-12, this table presents the maximum of the annual maximum facility concentrations. Note the Loading Tool does not display this column if you select Pathogen Indicators, Temperature, or Wastewater Flow for your search.
Pollutant measurements can be stored in ICIS-NPDES as mass quantities or concentrations. If the measurement of interest is a mass quantity, then the Loading Tool will back-calculate the average concentration using the mass quantity and wastewater flow. However, if the Loading Tool cannot identify a wastewater flow for this calculation, then it will display zero for the average concentration.
Total Pounds (lbs/yr)
Annual mass discharge of a pollutant to a receiving stream calculated using the methodology described in Section 3.3 of the Technical Users Background Document for the DMR Pollutant Loading Tool. Note the Loading Tool does not display this column if you select Pathogen Indicators, Temperature, or Wastewater Flow for your search.
This table does not display results that have a total annual load of zero.
Total TWPE (lbs-eq/yr)
The relative toxicities of different pollutant discharges (in units of TWPE) to a receiving stream in a year. TWPE is calculated by multiplying the pollutant mass (in pounds) by its toxic weighting factor. See Table 2-3. This value is not a measure of risk or potential for human health impacts but is a relative measure of the potential toxicity between pollutant discharges. Note the Loading Tool does not display this column if you select Pathogen Indicators, Temperature, or Wastewater Flow for your search.
Not all pollutants have a toxic weighting factor (for example, Total Suspended Solids), which means that these pollutants do not have a toxicity score (i.e., TWPE = 0).
Avg Flow (MGD)
The average of the average monitoring period flows (in units of millions of gallons per day) for the reporting year. For example, if a facility reports monthly wastewater flows, the facility average flow is the arithmetic average of the reported monthly wastewater flows. For each HUC-12, this table presents the average of the facility average wastewater flows.
This result will be zero if a wastewater flow was not reported by the facility, or if the Loading Tool was unable to match the pollutant loading to a wastewater flow in the Loading Tool database.
Total Annual Flow (MMGal)
The total annual wastewater volume (in units of millions of gallons) in a reporting year. Note the Loading Tool only displays this column if you select Wastewater Flow in your search.
This table does not display results that have a total annual flow of zero.

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Top SIC Discharges in Pounds/Toxic Weighted Pounds (TWPE) (Year)

This table lists the SIC codes with the ten largest discharges for a given year that meet your search criteria. The SIC code discharges are ranked in order of decreasing pollutant mass. For some pollutants you can select the name to obtain more information about it. For a complete list of all pollutants select the "Download All Data" button.

4-digit SIC Code
Code that describes the primary activity of the facility. The first two-digits define a major business sector and the last two-digits denote a facility's specialty within the major sector. See the U.S. Department of Labor website for more information
SIC codes are not required to be reported in ICIS-NPDES, and can be blank for some facilities in the Loading Tool database. However, the Water Pollution Search does not display results for facilities with blank SIC codes in this table.
SIC Description
Description that is linked to the 4-Digit SIC Code that identifies the primary activity of the facility.
Top Pollutant
The name used in ICIS-NPDES to identify the substance discharged. Of the pollutants discharged by each SIC code, the pollutant with the highest annual load is listed.
Top Pollutant Pounds
For the top pollutant for each SIC code, the annual mass (in units of pounds) discharged to a receiving stream. This table does not display pollutants that have a total annual load of zero.
Top Pollutant TWPE
For the top pollutant for each SIC code, the relative toxicities of different pollutant discharges (in units of TWPE) to a receiving stream. TWPE is calculated by multiplying the pollutant mass (in pounds) by its toxic weighting factor. This value is not a measure of risk or potential for human health impacts but is a relative measure of the potential toxicity between pollutant discharges.
Not all pollutants have a toxic weighting factor (for example, Total Suspended Solids), which means that these pollutants do not have a toxicity score (i.e., TWPE = 0).
When available you can select the name to obtain more information about it. For a complete list of all pollutants select the "Download All Data" button.

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Top Facility Discharges in Pounds/Toxic Weighted Pounds (TWPE) (Year)

This table lists the facilities with the ten largest discharges that meet your search criteria. The facility loads are ranked in order of decreasing pollutant pounds.

The "Browse All Facilities" button will provide a list of all facilities meeting the search criteria. For a complete list of all pollutants click the "Download All Data" button.

NPDES ID
A nine-character code used to uniquely identify a permitted NPDES facility. The NPDES permit program regulates the direct discharge of pollutants into US waters.
Facility Name
The primary name used to identify a facility in ICIS-NPDES. Select the facility name to bring up the facility information page.
City, State
The city name and two-character state abbreviation for the facility location. City names can be blank in FRS and ICISNPDES. The Water Pollution Search will display states for all facilities and the city name, if provided.
SIC Code
Four-digit code that describes the primary activity of the facility. The first two-digits of the code define a major business sector; the third and fourth digits denote a facility's specialty within the major sector. See the U.S. Department of Labor website for more information. SIC codes are not required to be reported in ICIS-NPDES and can be blank for some facilities.
HUC-12 Code
Hydrologic Unit Code (HUC) code assigned by the US Geological Survey used to classify watersheds in the United States and the Caribbean. Code consists of two to twelve digits based on six levels of classification:
  • Region (first-level, 2-digit HUC)
  • Subregion (secondlevel, 4-digit HUC)
  • Accounting unit (third-level, 6-digit HUC)
  • Cataloguing unit (fourth-level, 8-digit HUC)
  • Watershed (fifth-level, 10-digit HUC)
  • Subwatershed (sixth-level, 12-digit HUC)
The Loading Tool obtains this data element using a Watershed Assessment Tracking and Environmental ResultS (WATERS) web service (OWRAD/PCS_WMERC) which obtains the HUC-12 code from the Natural Resources Conservation Service's Watershed Boundary Dataset. The Watershed Boundary Dataset does not include HUC-12's for all NPDES permits in ICIS-NPDES. As a result the HUC-12 can be blank for some facilities in the Loading Tool database.
Top Pollutant
The pollutant name used in ICIS-NPDES to identify the substance discharged.
Total Pollutant Pounds (lbs/year)
Annual mass discharge of a pollutant to a receiving stream (in units of pounds/year). Select the Top Pollutant Pounds to see a breakdown of the facility loading calculations.
Average Daily Flow (MGD)
The average of the average monitoring period flows (in units of millions of gallons per day) for a reporting year. For example, if a facility reports monthly wastewater flows, the facility average flow is the arithmetic average of the reported monthly wastewater flows.
This result will be zero if a wastewater flow was not reported by the facility, or if the Loading Tool was unable to match the pollutant loading to a wastewater flow in the Loading Tool database.

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