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Discharge Monitoring Report (DMR) Pollutant Loading Tool

Note: The tool uses discharge monitoring report (DMR) data from ICIS-NPDES and PCS to calculate pollutant discharge amounts. EPA has verified the accuracy of the tool’s calculations. EPA has also performed a limited review of the underlying data that has focused on facilities with the largest amounts of pollutant discharges. Due to the large amount of DMR data, additional errors exist in ICIS-NPDES and PCS. Please see the User Guide (29 pp, 2.6MB), Frequently Asked Questions and Answers, and Error Correction page for instructions on how to use the tool and how to correct errors in ICIS-NPDES and PCS. You can send an email to waterloadings@epa.gov with any comments or questions about the tool. You can sign up for our e-mail news bulletin and be notified when new data, enhancements, or training materials are available. The tool also uses wastewater pollutant discharge data from the Toxics Release Inventory (TRI).

Overview

The Discharge Monitoring Report (DMR) Pollutant Loading Tool is a new tool designed to help you determine who is discharging, what pollutants they are discharging and how much, and where they are discharging. The tool calculates pollutant loadings from permit and DMR data from EPA‘s Permit Compliance System (PCS) and Integrated Compliance Information System for the National Pollutant Discharge Elimination System (ICIS-NPDES). Data is available for the years 2007 through 2011. Pollutant loadings are presented as pounds per year and as toxic-weighted pounds per year to account for variations in toxicity among pollutants. The tool ranks dischargers, industries, and watersheds based on pollutant mass and toxicity, and presents “top ten” lists to help you determine which discharges are important, which facilities and industries are producing these discharges, and which watersheds are impacted.

The tool also includes wastewater pollutant discharge data from EPA’s Toxics Release Inventory (TRI). Data is available for the years 2007 through 2011. Users can search TRI data to find the facilities with the largest pollutant discharges to surface waters or sewage treatment plants (a.k.a. Publicly-Owned Treatment Works – “POTWs”). Users can also compare the DMR data search results against TRI data search results and vice versa. The tool clearly labels the source of data when displaying search results but does not mix TRI or DMR data when calculating pollutant discharges.

If this is your first time using the tool then you might want to start with the EZ Search (DMR data) or the TRI Search (TRI data). If you need more flexibility with your searches you might want to try the Advanced Search (DMR data). If you have additional questions or would like more information about the tool, you can access more detailed information in the User Guides/Tech Documents tab.

Read on to learn more about:

How to Navigate the Tool

Whether you are a general user or a more technical user, this tool provides several search options to help you access wastewater pollutant discharge data, for example:

  • If you are a general user, you can use the EZ Search or TRI Search to quickly find discharge monitoring data or TRI data based on simple searches.
  • If you are a technical user (e.g., NPDES permit writer, researcher, watershed modeler, or regulatory agency), you can use the Advanced Search to access more detailed discharge monitoring data that you can download in a comma-separated value (CSV) file for further analysis in your own software application.

You can navigate the Loading Tool home page using the following seven tabs:

  1. EZ Search: General users can perform simple searches using DMR data. Results are displayed on a Web page in “top ten” lists to help you determine which discharges are important, which facilities and industries are producing these discharges, and which watersheds are impacted.
  2. TRI Search: Similar search interface and display results as EZ Search but the data source is TRI data.
  3. Data Explorer: General users can create a thematic map of the United States in which states are shaded in blue in proportion to the user’s search criteria. For example, the user can visually see the number of POTWs in each state with states shaded in dark blue having the most number of POTWs.
  4. Facility Search: Provides direct access to facility-level information, one facility at a time, with the facility name or unique identifier (e.g., NPDES ID).
  5. Advanced Search: Designed for technical users and provides increased flexibility on searching DMR data. Results are provided as a comma separated value (CSV) file for post-processing by the user.
  6. Everyday Searches: Provides access trend charts and other ‘canned’ searches (by geographic location, industry sector, and/or pollutant) of DMR data that are often used by technical users. In particular, the “Facility Loading Calculations” on this tab will detail exactly how the tool calculates annual pollutant loads using DMR data.
  7. User Guides/Technical Documents: Provides the instructions, guides, and metadata to assist users with the Loading Tool.

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Loading Tool Data Sources

The Loading Tool uses discharge monitoring and permit data from PCS and ICIS-NPDES. PCS and ICIS-NPDES are databases that automate entering, updating, and retrieving discharge monitoring and permit data:

  • PCS and ICIS-NPDES are national in scope, including data from all 50 states and 21 U.S. territories and tribes;
  • PCS and ICIS-NPDES contain discharge data that facilities determine through effluent chemical analyses and metered flow; and
  • PCS and ICIS-NPDES collectively include information for facilities in all point source categories that discharge directly to receiving streams.

Dischargers submit discharge monitoring data to their permitting authority (typically the state) using discharge monitoring reports (DMRs). The permitting authority then enters these data into PCS or ICIS-NPDES and checks whether the discharger is in compliance with the NPDES permit requirements.

Permit data include NPDES permit limits for water quality parameters (e.g., dissolved oxygen and temperature), specific chemicals (e.g., phenol), bulk parameters (e.g., biochemical oxygen demand), and flow. The permitting authority enters these data into PCS or ICIS-NPDES. PCS and ICIS-NPDES also include information on the facility’s permit requirements, such as monitoring frequency.

The Loading Tool also uses data from the Toxics Release Inventory (TRI). While TRI is national in scope, not all facilities report their pollutant discharges to TRI and not all pollutants that are discharged are reported to TRI. A facility must report their releases to TRI if it: (1) is in a specific industry sector (e.g., manufacturing, mining, electric power generation); (2) employs 10 or more full-time equivalent employees, and (3) manufactures or processes >25,000 lbs. of a TRI-listed chemical or otherwise uses >10,000 lbs. of a listed chemical in a given year. Note that persistant bioaccumulative toxic chemicals (PBTs) have lower reporting thresholds. See the Basics of TRI Reporting and Factors to Consider When Using TRI Data (PDF) (29 pp, 192K) for more information.

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Data Scope and Limitations

Before you begin your searches, there are some things you should know about the scope and limitations of the pollutant loadings calculated by the Loading Tool:

DMR Data

Facility Universe

You should understand that while the Loading Tool includes discharges for more than 44,000 facilities, it is not a complete inventory of all discharges permitted under the Clean Water Act.

Although the Clean Water Act requires all point source dischargers to obtain a NPDES permit and monitor their wastewater, not all facility, permit, or discharge monitoring datas are uploaded into PCS and ICIS-NPDES. EPA places greater priority on major facilities, and requires authorized states to provide more information about the compliance status of these dischargers. Specifically, EPA policy requires the permitting authority to enter facility, permit, and DMR information from “major” dischargers into either PCS or ICIS-NPDES. EPA policy requires a more limited set of data be shared with EPA through data entry into PCS or ICIS-NPDES (PDF) (14 pp, 4.6MB) for “non-major” (or “minor”) facilities. Many authorized states also transmit facility, permit, and DMR data for non-major dischargers to the PCS or ICIS-NPDES databases. The links below detail the amount of DMR data that the states share with EPA’s PCS or ICIS-NPDES databases. These data come from EPA’s State Review Framework, which allows EPA to identify recommendations for improvement to ensure fair and consistent enforcement and compliance programs across the states. There are also differences between the states on sharing facility level data with EPA’s PCS or ICIS-NPDES databases for general permit covered facilities (e.g., oil and gas extraction facilities, construction stormwater sites). EPA and states issue general permits to increase the efficiency of the permit program as multiple similar facilities can be regulated under one permit.

The Loading Tool contains information for industrial and municipal point source dischargers. Other types of Clean Water Act releases that are not available in the Loading Tool include:

  • Wastewater releases from industrial facilities that are connected to a publicly-owned treatment works (POTW) sewerage system, regulated through the CWA Pretreatment Program;
  • Biosolids monitoring data, regulated through the CWA Biosolids Program;
  • Discharges related to wet-weather events, such as stormwater from municipal separate storm sewer systems (MS4s), stormwater from industrial facilities, discharges from construction activities, combined sewer overflows, sanitary sewer overflows, and concentrated animal feeding operations (CAFOs).

Although the Clean Water Act requires all point source dischargers to obtain a NPDES permit and monitor their wastewater, not all discharges are uploaded into PCS and ICIS-NPDES. EPA places greater priority on major facilities, and requires authorized states to provide more information about the compliance status of these dischargers. Specifically, EPA policy requires the permitting authority to enter DMR information from “major dischargers” into either PCS or ICIS-NPDES. Many authorized states also transmit DMR data for “minor dischargers” to the PCS or ICIS-NPDES databases.

Pollutant Universe

The Loading Tool includes approximately 1,000 pollutant parameters including specific chemicals (e.g., phenol), bulk parameters (e.g., biochemical oxygen demand), temperature, and wastewater flow. However, these pollutants do not account for all pollutants discharged to U.S. waters.

  • PCS and ICIS-NPDES only include information about discharges of pollutants that a facility is required by permit to monitor; facilities are not required to monitor or report all pollutants they actually discharge.
  • Discharge data are entered into PCS and ICIS-NPDES using a variety of measurement units. The Loading Tool can only calculate mass discharges for pollutants that are measured either as mass quantities or concentrations. Therefore some pollutants, such as toxicity parameters measured as percent, are excluded from the Loading Tool. Further, the Loading Tool cannot calculate a load for concentration measurements if a wastewater flow measurement is not provided.

Additionally, EPA policy requirement requires a more limited set of facility, permit and DMR data be shared with EPA through data entry into PCS or ICIS-NPDES for non-major facilities. Data sharing for these non-major facilities varies across the different state NPDES permit programs. Consequently, the Loading Tool will not identify all non-major facilities if you limit a search to a particular pollutant. The Loading Tool uses permit data to count facilities when the user searches on a particular pollutant.

Matching Facilities to Watersheds

The Loading Tool matches facilities to receiving watersheds based on a facility’s latitude and longitude coordinates and watershed spatial data in the Natural Resources Conservation Service’s Watershed Boundary Dataset (view the NRCS website). The Loading Tool cannot establish a match between a facility and a watershed if either:

  • The facility does not have latitude or longitude coordinates; or
  • There are no spatial data for the receiving watershed.

The Loading Tool uses names from the USGS Geographic Names Information System (GNIS). The GNIS is closely integrated with the National Hydrography Dataset (NHD), which makes these data more useful for plotting on maps and for watershed modeling and other research. Not all waterbodies receiving wastewater discharges have names in the GNIS and the not all names in the GNIS match the names that facilities provide in their NPDES permit application.

Data Quality

DMR data may be entered into the PCS or ICIS-NPDES database manually, which can lead to data-entry errors. The database supporting this online tool uses data extracts from PCS and ICIS with regular error correction updates from EPA's Integrated Error Correction Process. The Integrated Error Correction Process allows EPA to track and incorporate into the Loading Tool database error corrections submitted by the public. EPA also works with states to identify any error corrections that they make to their data outside of the Integrated Error Correction Process. After the migration of all remaining 15 PCS states to ICIS-NPDES (likely at the end of December 2012), EPA can begin the process of automating extracts from ICIS-NPDES on a monthly basis for the Loading Tool database. This will enable EPA to more completely catch all of the error corrections made in ICIS-NPDES.

Intermittent Dischargers

Some facilities have intermittent discharges and may have one or more outfalls that don’t discharge for one or more months. Both PCS and ICIS-NPDES have ways of identifying when there is no discharge at a particular outfall for an entire monitoring period. In such cases the Loading Tool does not calculate pollutant loads for these outfalls during these monitoring periods.

EPA also developed a methodology with the states to estimate intermittent discharges that occurring within a monitoring period (e.g., there is a discharge from the outfall but it only occurs two days out of the monthly monitoring period). Specifically, the Loading Tool uses three ICIS-NPDES "Duration of Discharge" codes for identifying these intermittent dischargers: 50037, 82517, and 81381. The Loading Tool will automatically adjust the pollutant loading calculation such that the calculation only estimates pollutant discharges for the time when the outfall is discharging (e.g., two days in the month instead of the entire month).

However, there is a limitation with ICIS-NPDES data in that not all NPDES permits require permittees to submit these Duration of Discharge codes when they intermittent discharges that occurring within a monitoring period. Consequently, the tool may overestimate pollutant discharges for these intermittent dischargers that do not report these Duration of Discharge codes. NPDES permittees with intermittent discharges are encouraged to engage with their permit writers to add one of these Duration of Discharge codes to their DMR. NPDES permittees can also contact EPA (waterloadings@epa.gov) if these Duration of Discharge codes are not yet in their DMR.

TRI Data

Facility Universe

TRI reporting is limited to industrial facilities (i.e., POTWs do not report to TRI) and not all industry sectors report to TRI. Additionally, small establishments (less than 10 employees) are not required to report, nor are facilities that don't meet the reporting thresholds. Thus, facilities reporting to TRI may be a subset of an industry. See the Basics of TRI Reporting and Factors to Consider When Using TRI Data (PDF) (29 pp, 192K) for more information.

Pollutant Universe

TRI reporting focuses on toxic pollutant discharges and does not include common wastewater pollutants like Total Suspended Solids and Biochemical Oxygen Demand, which can be important factors when assessing the potential impact to surface waters. Additionally, the TRI Program doesn’t require additional monitoring, so reported releases are often, in part, based on estimates, not measurements, and, due to TRI guidance, may differ greatly from DMR data, especially at facilities with large wastewater flows. Finally, certain chemicals (polycyclic aromatic compounds [PACs], dioxin and dioxin-like compounds, metal compounds) are reported as a class, not as individual compounds. Because the individual compounds in most classes have widely varying toxic effects, the potential toxicity of chemical releases can be inaccurately estimated.

Matching Facilities to Watersheds or to POTWs

TRI reporting does require facilities to report the names of the surface waterbodies and POTWs that receive their wastewater discharges. See Sections 5.3 and 6.1 in TRI Form R. However, these reported names are not standardized or indexed to the NHD or EPA’s Federal Registry System (FRS). Consequently, it is not currently possible to accurately match TRI reporters to the receiving waterbody or POTW that is receiving their wastewater discharges.

Data Quality

The TRI Program conducts a number of activities every year to ensure the quality of TRI data reported to EPA. These activities range from providing extensive reporting guidance, intelligent reporting software, and training to facilities prior to the reporting deadline as well as data validation and analysis after the data are received. See the TRI Data Quality Program Information page for more information on these activities.

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State Review and Testing

2013 – Version 1.2 Testing and Release

In response to comments and suggestions from the public and EPA TRI Regional staff, OECA and OEI's TRI Program have jointly developed new enhancements to the Loading Tool as Version 1.2 (PDF) (4 pp, 59K).

2012 – Version 1.1 Testing and Release

In response to comments and suggestions EPA incorporated new enhancements to the Loading Tool as Version 1.1 (PDF) (18 pp, 257K). These included incorporated 2011 DMR and TRI data into the Loading Tool and by providing more flexibility in creating searches.

2010 – Beta Version Testing and Release

EPA initially released the Loading Tool as a beta version on 2 December 2010 with 2007 data to incorporate early public input on the development of the new tool. EPA received 38 comments during the public comment period. EPA reviewed these comments and incorporated suggested enhancements into the tool. See the following comment response document (PDF) (121 pp, 5.4MB) for the public comments and EPA responses to these comments. EPA continues to solicit input and suggestions on the tool. You can send your comments and suggestions to: waterloadings@epa.gov. You can sign up for our e-mail news bulletin and be notified when new data, enhancements, or training materials are available.

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