Discharge Monitoring Report (DMR) Pollutant Loading Tool

The DMR Pollutant Loading Tool (“Loading Tool”) is a new Web-based tool that calculates and reports facility pollutant discharges in pounds per year or by monitoring period. The tool also weights chemicals by their relative toxicity and calculates the toxic-weighted equivalent amount of each chemical released. With this tool you can rank facilities and pollutants by total amount of each pollutant released each year and by the total amount of toxic-weighted pounds released each year. The tool allows users to quickly identifies the facilities that discharge the largest amount of particular pollutants or pollutant groupings with simple filters:

• Location (e.g., State, Zip Code, Watershed),
• Type of Pollutant, and/or
• Type of Discharger (e.g., municipal wastewater treatment plants, industrial facilities).

The Loading Tool has six different tabs where you can conduct searches.

1. EZ Search (DMR): 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 (DMR) 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.

See the User‘s Guide for the Discharge Monitoring Report (DMR) Pollutant Loading Tool (PDF) (29 pp, 2.6MB) for more information.

The Clean Water Act (CWA) requires anyone who wants to discharge pollutants from point sources to first obtain an NPDES permit, or else that discharge will be considered illegal. As authorized by the Clean Water Act, the National Pollutant Discharge Elimination System (NPDES) permit program controls water pollution by regulating point sources that discharge pollutants into waters of the United States. Point sources are discrete conveyances such as pipes or man-made ditches. For example, NPDES permits control municipal and industrial sources of wastewater pollution. Permits typically require monitoring and reporting. NPDES permits limit a facility’s discharge of water quality parameters, specific chemicals, bulk parameters, and flow.

The permit provides two levels of control: technology-based limits (based on the ability of dischargers in the same industrial category to treat wastewater) and water quality-based limits (if technology-based limits are not sufficient to provide protection of the water body). See EPA‘s Industrial Water Pollution Controls Web page and Water Quality Standards for Surface Waters Web page for more information. The Water Permits Division of EPA’s Office of Wastewater Management directs and organizes the program in cooperation with EPA regional offices, states, tribes, and others.

The CWA allows EPA to authorize States, tribes, and territories to operate the NPDES program if these entities demonstrate they have the authority and capability to run the program, and if their environmental enforcement authorities are at least as stringent as Federal law. EPA uses memoranda of agreement between the EPA and states to define baselines and set collaborative expectations for program characteristics, permitting, monitoring, inspections, and enforcement activities. See EPA regulations at 40 CFR part 123. EPA has delegated permitting authority to 46 states, while EPA retains primary authority in the remainder of states, tribes, and territories. For more information on this permit program see the NPDES Permit Writers‘ Manual. Since its introduction in 1972, the NPDES permit program is responsible for significant improvements to our nation‘s water quality.

The CWA and NPDES regulations require permitted facilities to monitor the quality of their discharge and report data to the permitting authority. The NPDES permitting authority, EPA and authorized states, have unique policies and procedures to establish appropriate frequencies, procedures, and locations for monitoring. Facilities report pollutant discharge monitoring data in their Discharge Monitoring Report (DMR) as mass-based quantities (e.g., pounds per day) and/or concentrations (e.g., mg/L); however, discharges are reported using a wide variety of units. EPA’s regulations at §122.41(l)(4)(i) require that monitoring results must be reported on a DMR form. View an example DMR form (PDF) (2 pp, 191K). Authorized states may use different forms for the permits that they write.

Unless waived the permitting authority and included as a condition in the permit, the minimum frequency for DMR submissions is once per year. The permit writer can also require reporting more frequent than annually. Many NPDES permits require monthly DMR submissions to the permitting authority.

Yes. Permitted facilities must monitor the quality of their discharge and report this data to their permitting authority. This is one of the central tenets of the National Pollutant Discharge Elimination System (NPDES) Permitting Program. Facilities are required to report their discharge monitoring data on DMRs. Additionally, if any facility monitors a pollutant more frequently than required by the permit, the results of this additional discharge monitoring will also be submitted on their DMR to their NPDES permit authority. Failure to report or failure to report truthfully can result in civil penalties or in criminal penalties. For more information see EPA regulations at 40 CFR 122.41(l)(4) and (k) and the NPDES Permit Writers‘ Manual. Finally, EPA and states can also conduct unannounced, independent wastewater sampling. More information can be found on the NPDES Compliance Inspection Manual website.

EPA publishes laboratory analytical methods that are used by industries and municipalities to analyze the chemical, physical and biological components of wastewater and other environmental samples that are required by regulations under the authority of the CWA. Most of these methods are published as regulations in the Code of Federal Regulations (CFR) at Title 40 Part 136. EPA also allows NPDES regulated facilities to use alternative analytical wastewater methods. Information about the laboratory analytical methods is not collected on DMRs, which means that the Loading Tool cannot identify the laboratory analytical methods used by NPDES dischargers.

In administration and oversight of the NPDES program, EPA has divided NPDES permit holders as either “major” or “non-major” (a.k.a. “minor”) dischargers. For example, EPA identifies municipal wastewater treatment plants (a.k.a., Publicly-Owned Treatment Works (POTWs)) that discharge 1 million gallons per day or more as “major” dischargers. EPA has traditionally placed greater priority on major facilities, and has required 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 discharges” into one of two EPA databases: Permit Compliance System (PCS) or Integrated Compliance Information System for NPDES (ICIS-NPDES). Many authorized states also transmit DMR data for “minor dischargers” to the PCS or ICIS-NPDES databases. The PCS and ICIS-NPDES databases enable permitting authorities to monitor facility compliance with their permit requirements. Information about what data is required to be reported can be found on the Summary of EPA Compliance & Enforcement Data Entry Requirements in ECHO.

EPA recently announced through its Clean Water Act Action Plan a new approach for collecting DMR data from all NPDES permitted facilities. EPA will require DMR data to be submitted electronically by NPDES permitted facilities. Electronic data collection will provide more complete, accurate and timely information to both regulators and the public.

PCS dates back to the early beginnings of the NPDES permit program. Since 1974 EPA has used PCS to collect, manage, and report DMR data. EPA is now replacing PCS with a modernized database called the Integrated Compliance Information System for NPDES (ICIS-NPDES). EPA is steadily migrating authorized state NPDES and tribal permit programs from PCS reporting to ICIS-NPDES reporting.

Eventually, all authorized state NPDES programs will report DMR data to ICIS-NPDES instead of PCS, although the exact date is unknown. As of November 2011, PCS is used for 16 states and ICIS-NPDES is used for 34 states, Indian Country lands, and 19 other U.S. territories. ECHO provides more details on which database is used for the different states, tribes, and territories.

Dischargers submit discharge monitoring data to their permitting authority using discharge monitoring report (DMR) forms (PDF) (2 pp, 191K). Authorized states may use different forms for the permits that they write.

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. Many authorized state program review hard copy forms and hand enter DMR data into either PCS or ICIS-NPDES. Some authorized states provide permittees the ability to electronically submit DMR data. EPA also supports NetDMR, which is a national tool that allows NPDES permittees to electronically submit DMR data via a secure Internet application to EPA’s ICIS-NPDES database through the Environmental Information Exchange Network.

All authorized states are required to report facility and some permit data (PDF) (14 pp, 4.6MB) for all facilities (“major” and “non-major”). For “major” facilities, EPA expects authorized states to enter compliance and enforcement information into the national databases for at least 95% of their permitted facilities. For “non-major” (or “minor”) facilities, EPA does not require authorized states to enter compliance and enforcement information into PCS or ICIS-NPDES; however, many authorized states are providing the information voluntarily. You can also use the Clean Water Act Annual Noncompliance Report (ANCR) to see recent information (Calendar Year 2008) about facilities designated as “non-majors”. Authorized states that do not provide the data into the national system are required to have their own tracking systems to review incoming reports for violations. The Completeness of Clean Water Act Discharge Monitoring Data by State - Universe Facilities map shows the percentage of individually permitted “majors” and “non-majors” that have DMR data in EPA’s data systems (PCS or ICIS-NPDES).

EPA policy requires that facility data (e.g., facility site name, city, state, longitude, latitude) be shared between states and EPA for all facilities. However, EPA policy only requires states to share data on effluent limits (e.g., parameter limited, limit set type) and DMRs with EPA for major facilies. States do share permit (including effluent limits) data and DMR data with EPA for non-major facilities; however, this data sharing varies across the different state NPDES programs. Consequently, a search in the Loading Tool that specifies a particular parameter will only return facilities when there is match in PCS or ICIS-NPDES. Similarly, not all facility level data on general permit covered facilities are included in PCS or ICIS-NPDES. EPA and states issue general permits to cover multiple facilities in specific categories of discharges. General permits can be a cost-effective option for agencies because of the large number of facilities that can be covered under a single permit. Where a large number of similar facilities require permits, a general permit allows the permitting authority to allocate resources in a more efficient manner and to provide timelier permit coverage than issuing an individual permit to each facility. In addition, using a general permit ensures consistent permit conditions for comparable facilities. However, most general permits are classified by EPA and states as 'non-majors,' which means that a more limited set of facility, permit, discharge, and inspections data is entered into EPA’s data systems (PCS & ICIS-NPDES). More information on general permits can be found in the NPDES Permit Writers’ Manual.

EPA recently announced through its “Clean Water Act Action Plan” a new approach for collecting DMR data from all NPDES permitted facilities. EPA will require DMR data to be submitted electronically by NPDES permitted facilities. Electronic data collection will provide more complete, accurate and timely information to both regulators and the public. Under the Clean Water Action Plan, EPA is working to enhance public transparency regarding clean water enforcement performance at federal and state levels, to strengthen that performance, and to transform EPA‘s water quality and compliance information systems. This new tool is part of this effort to increase the availability and utility of DMR data.

A major part of the Clean Water Action Plan is a forthcoming EPA rulemaking (“NPDES Electronic Reporting Rule”), which will increase the amount of DMR data available to the public. The NPDES Electronic Reporting Rule will identify the essential information that EPA needs to receive electronically, primarily from NPDES permittees with some data required from NPDES agencies (NPDES-authorized States, territories, and tribes) to manage the national NPDES permitting and enforcement program. Through this regulation, EPA seeks to ensure that such facility-specific information would be readily available, accurate, timely and nationally consistent on the facilities that are regulated by the NPDES program. This new tool will incorporate this electronically submitted DMR data and increase the availability and utility of DMR data.

The Loading Tool includes pollutant loadings data calculated using discharge monitoring and permit data from PCS and ICIS-NPDES. Specifically, depending on the type of search you perform, you can view facility information (name, location, permit IDs, flow, receiving waters), pollutant concentrations and loads (average pollutant concentration, average daily load, maximum pollutant concentration, total pounds of pollutant per year), toxicity information, and flow data. The Loading Tool also includes data from the Clean Watershed Needs Survey and EPA Watershed Assessment, Tracking & Environmental ResultS (WATERS) database. The following figure provides a broad overview of the data sources that support the Loading Tool.

The tool also includes wastewater pollutant discharge data from EPA’s Toxics Release Inventory (TRI). Data is available for the years 2007 through 2010. Users can search TRI data to find the facilities with the largest pollutant discharges to surface waters or municipal 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. See the Basics of TRI Reporting and Factors to Consider When Using TRI Data (PDF) (29 pp, 192K) for more information.

The Loading Tool only includes wastewater discharge data for TRI reporters and for point source discharges regulated under the NPDES program. Not all industrial facilities report their releases to surface waters or POTWs under the TRI program and not all NPDES compliance monitoring, is included in the Loading Tool. For example, the Loading Tool does not include the following NPDES compliance monitoring data: biosolids monitoring, municipal separate storm sewer systems (MS4s), Industrial Users that discharge to POTWs, combined sewer overflows, and sanitary sewer overflows. These data are not reported to PCS or ICIS-NPDES or these compliance monitoring data do not have related flow data that would allow an estimate of the amount (pounds) discharged. Also, the Loading Tool does not estimate the pollutant load for any pollutant that is not monitored and reported to PCS and ICIS-NPDES. The tool generally does not have information about pollutants associated with run-off and non-point sources (e.g., agriculture, etc.). The ECHO Users Guide -- Understanding Federal and State Data Entry Requirements provides a summary of the data entry requirements for “major” and “non-major” permits.

The Loading Tool data are from PCS, ICIS-NPDES, and TRI, and therefore only include discharges of pollutants that a facility is required by permit to monitor and/or report. The data do not include all pollutants actually discharged as facilities are not required to monitor all the pollutants that they discharge. The Loading Tool can only calculate mass loadings for pollutants that are measured in units of concentration or mass. Therefore some pollutants, such as toxicity parameters reported as a percent, are excluded from the Loading Tool. Certain pollutants that are tracked in ICIS-NPDES and PCS are excluded from the analysis because it would not make sense to add those releases to an annual total (for example, some permittees have temperature limits).

No. The EZ Search (DMR) does not estimate pollutant discharges for these facilities. Consequently users must be aware of this important limitation when considering the results from the EZ Search (DMR). However, the Advanced Search does provide users with the option of estimating pollutant discharges using the permit limits data in PCS or ICIS-NPDES. Under the Clean Water Action Plan, EPA is working to enhance public transparency regarding clean water enforcement performance at federal and state levels.

No. The Loading Tool only calculates pollutant discharges from DMRs, which are submitted from permitted point sources. The Loading Tool also provides pollutant releases to POTWs and surface waters from industrial facilities, which are mostly related to point source discharges. Nonpoint source (NPS) pollution, unlike pollution from industrial and sewage treatment plants, comes from many diffuse sources. NPS pollution is caused by rainfall or snowmelt moving over and through the ground. As the runoff moves, it picks up and carries away natural and human-made pollutants, finally depositing them into lakes, rivers, wetlands, coastal waters and ground waters. NPS pollution is a significant factor in impairments to water quality across the Nation. See what EPA is doing to address nonpoint source pollution.

No. The Loading Tool only calculates pollutant discharges from DMRs, which are submitted from facilities that have NPDES permitted outfalls (which in most cases are discharges to surface waters). The CWA regulates industrial discharges to POTWs (a.k.a. “indirect dischargers”) through the National Pretreatment Program. EPA’s regulations require these indirect dischargers to periodically monitor their wastewater discharges and report these data to their local POTW, if the POTW has an approved pretreatment program, or to their state or EPA. See 40 CFR 403.12(e) and (h). Compliance monitoring data on indirect discharges are not uniformly inputted into PCS or ICIS-NPDES so it is not possible to calculate pollutant loadings on a national basis from these industrial sources of wastewater.

However, the Toxics Release Inventory (TRI) program does require a specified list of industrial categories to report on discharges to surface waters and to POTWs for 593 individually listed chemicals and 30 chemical categories (including 3 delimited categories containing 62 chemicals). The Loading Tool’s TRI Search does allow users to see releases to POTWs for TRI reporters.

EPA regulations require that each NPDES permit include technology-based effluent limits based on national, industry specific requirements set by EPA (“effuent guidelines”) or case-by-case requirements established by the permit writer. See 40 CFR 122.44(a)(1). Additionally, NPDES permits must include water-quality based effluent limits for all pollutants or pollutant parameters that “are or may be discharged at a level which will cause, have the reasonable potential to cause, or contribute to an excursion above any State water quality standard, including State narrative criteria for water quality.” See 40 CFR 122.44(d)(1)(i). In addition to these requirements, NPDES permit writers may include effluent limits or monitoring requirements to comply with state water quality standards.

Yes. EPA has used DMR pollutant loadings and TRI data to review the pollutants discharged by industrial point source categories with existing effluent guidelines. EPA conducts this review to support publication of its biennial Effluent Guidelines Program Plan. Specifically, EPA uses DMR data in ICIS-NPDES and PCS and TRI data to rank industrial point source categories by the amount of pollutant discharged, in units of pounds or toxic-weighted pound equivalents. These rankings are used to prioritize categories for additional reviews and rulemakings. The release of the Loading Tool represents a data system modernization that allows EPA to provide a searchable interface that makes the information much more transparent and usable by the public.

You can use the Loading Tool to get access to discharge monitoring data. The information in the Loading Tool can help you determine which pollutant releases are important, and how they relate to watershed impairments. A wide range of questions can be answered. You should start with the EZ Search (DMR) and TRI Search as they were designed for more basic queries and the results are displayed in a “Top 10” list format on a Web page. For example: Which permittees in a watershed have the highest releases? In a given watershed, which pollutants are most frequently released? What are the comparative releases of facilities within a particular sector? For a given chemical, which facilities have permit limits, which facilities monitor but do not have limits, and which facilities have no information available?

Users that are familiar with DMR or TRI data can use the Facility Search tab to jump to a facility specific page with a facility name or unique identifier (e.g., NPDES ID, TRI ID). The Everyday Searches tab provides some of the more common searches with the results displayed graphically or in a comma-separated value (CSV) file format for post-processing. The Advanced Search provides more advanced users with increased flexibility on search criteria and provides data in a downloadable CSV file. Finally, the Data Explorer provides a graphical display of DMR data on a map of the United States. The following are some example uses of the Loading Tool for advanced users:

• Development of permitting and monitoring requirements for a NPDES permit (e.g., ‘reasonable potential’ analysis for water-quality based effluent limits. See 40 CFR 122.44(d)(1)(i));
• Identify those facilities with the largest amount of pollutant discharges above their permitted limits;
• Incorporate point source discharge data into watershed pollution budget plans (a.k.a. Total Maximum Daily Load (TMDL) plans);
• Incorporate point source discharge data into watershed modeling; and
• Improving the reviews of EPA Regional and State NPDES program quality (e.g., permit quality reviews, EPA/OECA’s State Review Framework).

The key search options include the EZ Search (DMR), TRI Search, Facility Search, Advanced Search, Data Explorer, and Everyday Searches. See the User’s Guide for Discharge Monitoring Report (DMR) Pollutant Loading Tool (PDF) (29 pp, 2.6MB) for guidance on using these search options.

The EZ Search (DMR) results include a green “L” icon to indicate when a facility has a NPDES effluent limit for a particular parameter.

Some NPDES permit programs require monitoring to assess whether effluent limits are necessary.

Facilities may be missing from the DMR Loading Tool because their DMR data have not been entered into ICIS-NPDES or PCS or they do not report to TRI. Permitting authorities are only required to submit DMRs for facilities that they have classified as “major” dischargers. Data for “non-major” facilities is very complete in some states, but in other states, data is not readily available. EPA is working with authorized states to improve coverage of data across the country, and the percent of available data is increasing each year. See the User’s Guide for Discharge Monitoring Report (DMR) Pollutant Loading Tool (PDF) (29 pp, 2.6MB) for tips on the Facility Search option. See Data Scope and Limitations for a map of DMR data completeness by state for “major” and “non-major” dischargers from 2007 to 2010.

See the User’s Guides and Glossary for additional guidance. Requests for more information can be directed to waterloadings@epa.gov.

The Technical Users Background Document for the DMR Pollutant Loading Tool (PDF) (143 pp, 2.4MB) describes the Loading Tool architecture and calculation methodologies in detail. The basic calculation steps include:

• Extracting DMR data from ICIS-NPDES and PCS;
• Converting measurements into standard units;
• Matching pollutant concentrations with wastewater flows to calculate loads (mass per unit time);
• Calculating monitoring period loads (mass per monitoring period);
• Applying methodologies to calculate loads for discharges reported as non-detect;
• Grouping parameters and aggregating nutrient loads;
• Calculating annual loads; and
• Applying estimation functions to estimate annual loads when monitoring reports are missing.

The Loading Tool also presents wastewater pollution discharge data reported under the TRI data program. These TRI data are reasonable estimates of the annual mass of pollutant releases to surface waters (“direct dischargers”) and POTWs (“indirect dischargers”).

The Technical Users Background Document for the DMR Pollutant Loading Tool (PDF) (143 pp, 2.4MB) provides the exact formulas and procedures for selecting DMR data to calculate annual pollutant discharges (in units of pounds and toxic-weighted pound equivalents). The Loading Tool can take representative pollutant monitoring data (in units of milligrams per liter (mg/L)) and multiply by the corresponding wastewater discharge (in units of million gallons of per day (MGD)) and a conversion factor to account for units. For example, if a facility discharges a pollutant with a concentration of 5 mg/L in a wastewater flow of 10 MGD in the month of January (31 days) then the corresponding calculation is:

Example Calculation:

Pollutant Discharge = 5 mg/L × 10 MGD × 31 days × 3.785 L/gal × 2.205 Pounds/Kg (in January)

= 12,936 pounds

The Technical Users Background Document for the DMR Pollutant Loading Tool (PDF) (143 pp, 2.4MB) provides in greater detail how the Loading Tool identifies the representative pollutant monitoring data for calculating pollutant discharges and how it uses these data to calculate annual pollutant discharges (in units of pounds and toxic-weighted pound equivalents).

As noted above the Loading Tool also presents wastewater pollution discharge data reported under the TRI data program. These data are reported as an annual mass amount of pollutant releases to surface waters (“direct dischargers”) and POTWs (“indirect dischargers”).

The user interface of the tool was developed using Adobe ColdFusion 8. More technical information is provided in the Technical Users Background Document for the DMR Pollutant Loading Tool (PDF) (143 pp, 2.4MB). The Loading Tool uses an Oracle 10g database to organize and manage its data.

EPA’s data systems (PCS and ICIS-NPDES) use data qualifiers (“No Data Indicators” or NODI) when there is some reason that data for one or more expected DMR values will not or should not be received. NODI data qualifiers may be entered for an entire expected DMR form, for a particular parameter, or for a particular limit. Facilities report a NODI code on their DMRs where no measurements are reported. The single character NODI code corresponds to a NODI description, which explains why no data are reported (e.g., no discharge, not quantifiable, conditional monitoring, and sampling equipment failure). The type of NODI code reported affects the annual load estimation performed by the Loading Tool. Incorrectly reported NODI codes can result in over or underestimating pollutant loads. For NODI codes that indicate no discharge, the Loading Tool calculates a pollutant discharge of zero for that pollutant for that outfall for that monitoring period.

EPA evaluated the set of NODI codes in PCS and ICIS-NPDES to identify which codes correspond to no discharge events. For example, a NODI code equal to “C” means that no discharge occurred for that monitoring period. However, for NODI codes that indicate a discharge may have occurred for that monitoring period, the Loading Tool estimates a discharge based on discharges reported for the other monitoring periods in that reporting year. For example, a NODI code equal to “G” means that monitoring was required for that monitoring period but not reported due to a sampling equipment failure. The Loading Tool identified the following NODI codes as representing conditions of no discharge:

EPA also notes that states do not all use the same method and codes for identifying these intermittent dischargers. In particular, ICIS-NPDES has three codes for reporting the Duration of Discharge (e.g., 50037, 82517, and 81381), which is an important parameter to estimate the amount discharged for these intermittent dischargers. Consequently, the tool may overestimate pollutant discharges for intermittent dischargers that only discharge in emergency situations (i.e., facilities with unscheduled limit sets). EPA will work with states to improve pollutant discharge calculations for these intermittent dischargers.

EPA’s NPDES regulations require annual sampling of permitted wastewater discharges as a minimum sampling frequency. Most permitted outfalls have more sampling with most the common sampling and reporting frequency being monthly. The Loading Tool uses reported pollutant concentrations and wastewater flows to estimate the pollutant loads where monitoring data are not reported to PCS or ICIS-NPDES. For example, if a facility reports bi-monthly then the Loading Tool will use the six reported monitoring results to estimate the pollutant discharges for the other six months where there is a discharge but no monitoring data. The table below provides an example of how the Loading Tool takes monitoring data from five months to calculate an annual load.

Finally, it is important to note that the EZ Search (DMR) does not calculate pollutant discharges for facilities that do not have any of their DMR data in PCS or ICIS-NPDES. For example, PCS and ICIS-NPDES do not have DMR data for many “non-major” facilities, which means the EZ Search (DMR) does not calculate pollutant loads for these facilities. Users can use the Advanced Search to estimate pollutant discharges for facilities with DMR data in PCS or ICIS-NPDES.

NPDES permit effluent limits and monitoring requirements can be numeric (e.g., average daily discharge of Total Suspended Solids not to exceed 30 mg/L) or narrative (e.g., best management practices). CWA section 402(a)(1) and (2) and the NPDES regulations at § 122.44(k) authorize BMPs in NPDES permits to control or abate the discharge of pollutants when numeric effluent limitations are infeasible, or when the practices are reasonably necessary to achieve effluent limitations and standards or to carry out the purposes and intent of the CWA. Most NPDES permits include numeric effluent limits and monitoring requirements, which are most often expressed as mass-based values (e.g., average daily amount (in units of pounds) not to exceed 2,500 pounds per day) or concentration-based values (e.g., average daily amount not to exceed 30 mg/L). NPDES permit writers also establish numeric effluent limits and monitoring requirements for pollutants that cannot be expressed in terms of mass or concentration (e.g., pH, temperature, radiation) or are better expressed through other means (e.g., unitless ratios). For example, pH is generally expressed as an acceptable range (e.g., 6.0–9.0 standard pH units). The Loading Tool uses numeric data from DMRs in PCS and ICIS-NPDES to calculate pollutant discharge amounts for each monitoring period and for each calendar year.

A monthly average effluent limits help control water pollution to avoid chronic effects on human health and water quality. NPDES permittees may sample daily or weekly and then average these values across and month to demonstrate compliance with the average monthly limit. The daily maximum effluent limit helps control water pollution to avoid acute effects on human health and water quality. NPDES permittees may sample daily or weekly and then report the single maximum value for the monitoring period, which is often monthly. Both sets of limits are used by NPDES permit writers to protect human health and the environment.

EPA also uses these two limit types with technology-based effluent limits. In establishing daily maximum limitations, EPA’s objective is to restrict the discharges on a daily basis at a level that is achievable for a facility that targets its treatment at the long-term average. EPA acknowledges that variability around the long-term average results from normal operations. This variability means that occasionally facilities may discharge at a level that is greater than the long-term average. This variability also means that facilities may occasionally discharge at a level that is considerably lower than the long-term average. To allow for these possibly higher daily discharges, EPA has established the daily maximum limitation. A facility that discharges consistently at a level near the daily maximum limitation would not be operating its treatment to achieve the long-term average, which is part of EPA’s objective in establishing the daily maximum limitations. That is, targeting treatment to achieve the limitations may result in frequent values exceeding the limitations due to routine variability in treated effluent. In establishing monthly average limitations, EPA’s objective is to provide an additional restriction to help ensure that facilities target their average discharges to achieve the long-term average. The monthly average limitation requires continuous dischargers to provide on-going control, on a monthly basis, that complements controls imposed by the daily maximum limitation. In order to meet the monthly average limitation, a facility must counterbalance a value near the daily maximum limitation with one or more values well below the daily maximum limitation. To achieve compliance, these values must result in a monthly average value at or below the monthly average limitation.

EPA‘s regulations at § 122.45(f)(1) stipulate that all pollutants limited in permits must have effluent limits, standards or prohibitions expressed in terms of mass except under any of the following conditions:

• For pH, temperature, radiation, or other pollutants that cannot appropriately be expressed by mass limitations.
• When applicable standards or limitations are expressed in terms of other units of measure.
• If in establishing technology-based permit limitations on a case-by-case basis, limitations based on mass are infeasible because the mass or pollutant cannot be related to a measure of production (e.g., discharges of TSS from certain mining operations). The permit conditions must ensure that dilution will not be used as a substitute for treatment.

Mass-based permit effluent limits encourage water conservation (e.g., minimize the potential for diluting process wastewaters by non-process wastewater, more efficient use of water) and pollution prevention (e.g., reduce waste loads to wastewater treatment facilities by physically collecting solid materials before using water to clean equipment and facilities). Additionally, for facilities with on-site wastewater treatment systems, the combination of water-reduction technologies and practices and well-operated wastewater treatment will reduce the volume and mass of discharged wastewater pollution (i.e., after treatment). Another benefit of mass-based permit effluent limitations is that they provide the permittee with more flexibility. Permittees may elect to control their wastewater discharges through more efficient wastewater control technologies and pollution-prevention practices that result in lower pollutant concentrations in the discharged wastewater, or more efficient water conservation practices that result in less wastewater volume discharged from industrial operations), or both.

Additionally, a permit writer may determine that it is beneficial to include concentration-based effluent limits to supplement the mass-based effluent limits. Where effluent limits are expressed in terms of mass, a provision at § 122.45(f)(2) allows the permit writer, at his or her discretion, to express effluent limits in additional units (e.g., concentration units). Where effluent limits are expressed in more than one unit, the permittee must comply with both. The permit writer may determine that expressing effluent limits in terms of both concentration and mass encourages the proper operation of a treatment facility at all times.

The detection limit is the minimum result from a wastewater sample that can be reliably discriminated from a blank sample (for example, with a 99% confidence level). The quantitation limit is the smallest detectable concentration of an analyte greater than the detection limit where the accuracy (precision and bias) achieves the objectives of the intended purpose. In practical terms, these two analytic methods limits put pollutant concentrations measured from a wastewater samples into three groupings:

• Pollutant concentrations that are below the analytic method detection limit are generally interpreted to mean that it is not reliable to determine that a pollutant is present;
• Pollutant concentrations that are above the analytic method detection limit but below the analytic method quantitation limit means that the pollutant may be present but the values are reported as estimated concentrations; and
• Pollutant concentrations at or above the analytic method quantitation limit means that the pollutants are present and that the pollutant concentration values are considered reliable.

NPDES dischargers are required to report the results of their wastewater sampling and add any appropriate qualifiers. EPA and State permitting authorities use data from NPDES permit applications and DMRs to determine whether pollutants are present in an applicant‘s discharge and to quantify the levels of all detected pollutants. These pollutant data are then used to determine whether technology- or water quality-based effluent limits are needed in the facility‘s NPDES permit. It is critical, therefore, that NPDES dischargers provide data that have been measured with precision and accuracy so that they will be meaningful to the decision-making process.

PCS and ICIS-NPDES allow EPA and state permit programs to identify pollutant concentrations that are below a certain value. These data systems allow EPA and state permit programs to identify pollutant concentrations that are below a certain value by using the less than qualifier (<). In PCS, the qualifier is saved with the reported data as the first character. In ICIS-NPDES, the qualifier is saved in a separate qualifier field and the reported data is saved in a separate value field.

ICIS-NPDES

The screen-shot of the DMR data entry screen for ICIS-NPDES shows what data are captured by ICIS-NPDES from the DMR. The green boxes and arrows demonstrate the work flow in entering DMR data into ICIS-NPDES.

Specifically, for each monitoring result (or “Statistical Base Code” in ICIS-NPDES terminology) the NPDES discharger will report, among other information, a value (see “E” in the above figure) and a qualifier (see “G” in the above figure). ICIS-NPDES qualifiers indicate how the actual value relates to the reported value. It defaults to “=” (equal to), but may also be used to indicated various types of uncertainty. Other available qualifiers are “>” (greater-than), “<” (less-than), “T” (too numerous to count), and “E” (estimated). When the less than qualifier (“<”) is used this means that the actual value was some unknown value less than the reported value. Consequently, ICIS-NPDES only allows EPA and state data entry professionals to identify a single value and qualifier when pollutant monitoring data are below the laboratory analytical method quantitation limit. The following is a common data entry procedure to accommodate this system restriction:

• “0” (the number zero) in the value field (see “E” in the above figure) and the “=” qualifier (see “G” in the above figure) when the pollutant concentrations are below the analytic method detection limit; and
• The analytic method quantitation limit in the value field (see “E” in the above figure) and the “<” qualifier (see “G” in the above figure) when the pollutant concentrations are below the analytic method quantitation limit.

PCS

PCS (the legacy) system uses two single character codes to collect and manage data that are that are below the laboratory analytical method detection limits or quantitation limits. Specifically, PCS uses a single character code that indicates why pollutant measurements are blank for a reporting period. NODI equal to “B” and “Q” are defined in the PCS Data Element Dictionary as “Below detection limit/no detection” and “Not quantifiable,” respectfully. Most facilities use NODI equal to “B” rather than “Q”. Based on 2007 data, NODI equal to “B” was reported for more than 250 parameters.

Most often facilities report the analytic method quantitation limit in the value field with a less-than (“<”) sign when the actual analytical sample measurements are less than the analytic method quantitation limit. However, some facilities leave the value field blank and reporting “B” in the NODI field when the actual analytical sample measurements are less than the analytic method quantitation limit.

If pollutant concentrations for all monitoring periods in a given year are reported below the laboratory analytical method quantitation limit then the annual load calculated by EZ Search (DMR) for that parameter is equal to zero. This means that all pollutant concentrations in a given year are either “0” or qualified with “<” (ICIS-NPDES) or qualified with “<” (PCS). In practical terms this means that pollutants may have been detected as present through wastewater sampling but never reliably quantified during the year.

EZ Search (DMR) uses a hybrid approach to calculating pollutant loads with at least one monitoring period has a pollutant concentration that is above the laboratory analytical method quantitation limit. This means that pollutants were reliably quantified at least once during the year, which confirms the presence of the pollutant in the wastewater discharge. In this case the EZ Search (DMR) annual pollutant load is the sum of:

• The product of the pollutant concentration data that are above the laboratory analytical method quantitation limit and the related wastewater flow, monitoring time period, and the appropriate conversion factors; and
• The product of one-half the laboratory analytical method quantitation limit and the related wastewater flow, monitoring time period, and the appropriate conversion factors.

It is important to note this method requires the reporting of the laboratory analytical method quantitation limit. In cases where there is no reported laboratory analytical method quantitation limit in PCS or ICIS-NPDES, the EZ Search (DMR) does not make an estimate of the laboratory analytical method quantitation limit and uses “0” (zero) for the pollutant load for that monitoring period. Additionally, PCS or ICIS-NPDES data entry errors where the “<” sign or other qualifier is inadvertently omitted means that the Loading Tool will treat such values without the “<” qualifiers as being above the laboratory analytical method quantitation limit (even though they may be reported on the paper DMRs with the appropriate “<” qualifiers). Finally, it is also important to note that the hybrid approach is the method EPA uses to calculate annual pollutant loadings for its review of industrial sources of wastewater and develop is Biennial Effluent Guidelines Program Plan (see Section 304(m) of the CWA).

EPA examined this relative difference with toxic pollutant discharges (in units of toxic-weighted pound equivalents). Toxic pollutant parameters are the most sensitive to these calculations as even very small discharges of some toxic pollutant discharges (in units of mass) equate to large amounts of toxic-weighted pound equivalents. EPA identified that only 0.12 percent of the toxic-weighted pound equivalents in 2007 are based on below detection level assumptions using the hybrid approach. The industrial categories showing the greatest sensitivity to below detection level assumptions include Superfund Sites, the Pulp, Paper and Paperboard Category, and the Petroleum Refining Category. Pollutant parameters showing the highest sensitivity to the below detection level assumptions include 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), TCDD equivalents, and chlorine.

EPA requires TRI reporters to make reasonable estimates of their releases to surface waters and POTWs (in addition to other air, land, and groundwater releases). TRI reporters may elect to use the following method to estimate their releases:

= ½ × laboratory analytical method quantitation limit × wastewater discharge volume × conversion factors

when all of their wastewater monitoring data is below the laboratory analytical method quantitation limit. For dioxin discharges, which are particularly toxic chemicals to human health, EPA guidance recommends the following: “[I}f a facility is not detecting dioxin or a particular dioxin-like compound using a particular method but has information that shows that they should be detecting them the facility should use this other information and it may be appropriate to estimate quantities using one half the detection limit.” See EPA’s “Guidance for Reporting Toxic Chemicals within the Dioxin and Dioxin-like Compounds Category.” (PDF) (78 pp, 165K). This means that the results for EZ Search (DMR) and TRI Search when pollutant concentrations are below the laboratory analytical method quantitation limit.

The Advanced Search currently provides three options for calculating annual loads. These include: (1) setting values below the analytic method quantitation limit equal to zero; (2) setting values below the analytic method quantitation limit equal to one-half times the analytic method quantitation limit; and (3) setting values below the analytic method quantitation limit equal to the analytic method quantitation limit.

The Loading Tool uses the formulas outlined in the Technical Users Background Document for the DMR Pollutant Loading Tool (PDF) (143 pp, 2.4MB). The Loading Tool does not round DMR data or apply significant figure rules prior to calculating pollutant discharges. For example, the EZ Search (DMR) may report a pollutant discharge of 547,139 pounds but does not round this calculated figure to a specified number of significant figures. The annual pollutant results are presented as they are calculated in order to facilitate error correction. Presenting results as they are calculated will allow users to perform their own hand calculations of pollutant loadings using pollutant and wastewater flow discharge data for each monitoring period (available through Advanced Search). Users can also download pollutant and wastewater flow discharge data for each monitoring period and apply their own rules for significant figures to calculate rounded pollutant loadings.

Pollutant discharges are reported in pounds and toxic-weighted pound equivalent (TWPE). EPA calculates TWPE 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.

• See EPA's Draft Toxic Weighting Factor Development in Support of CWA 304(m) Planning Process (104 pp, 1MB) for more information.

It is important to note that this value is not a measure of risk or potential for human health impacts. EPA presently lacks on a national scale the detailed exposure assessment data and tools necessary to complete a risk assessment with these DMR data (e.g., analyze for each industrial facility the fate and transport of discharged pollutants in an actual waterbody, exposure pathways of pollutants to populations in a watershed, and uptake of the discharged pollutants).

To convert pollutant loadings into TWPE, EPA multiplies the pollutant mass (in pounds) by its toxic weighting factor (TWF). For example, total mercury (CAS No. 7439976) has a TWF equal to 117 TWPE/lbs-mercury while total copper (CAS No. 7440508) has a TWF equal to 0.63 TWPE/lbs-copper. Therefore a discharge of 1 pound of mercury equals 117 TWPE discharged while a discharge of 1 pound of copper equals 0.63 TWPE discharged. 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).

EPA’s Office of Water’s Engineering and Analysis Division (EAD) developed TWFs for use in its effluent limitations guidelines and standards (ELGs) development program to allow comparison of pollutants with varying toxicities using data from PCS, ICIS-NPDES, and EPA’s Toxics Release Inventory (TRI). The DMR Pollutant Loading Tool makes this data more available to the public (as this facility specific TWPE discharges were previously available only through EPA’s docket system supporting its ELG program). These TWFs are available on the Users Guide/Technical Documents tab.

All results tables for the EZ Search (DMR) and Facility Search include a “Download All Data” button that produces a comma-separated value (CSV) file that users can save to their desktop and import into software of their choice. In addition, all Advanced Search results are provided as a CSV file. The Loading Tool also provides the means for users to download facility, permit and DMR data.

EPA is happy to provide the entire Loading Tool database to users; however, due to its size (˜20GB) EPA can only provide the complete database as an Oracle dump file. EPA recognizes that most users will not have Oracle capabilities; therefore, EPA can also provide portions of the database in Microsoft Access format. To obtain a Microsoft Access database with Loading Tool data, please first evaluate your data needs:

• Do I need monthly data or annual data?
     –– The annual dataset is significantly smaller than the monthly dataset and can be stored in an MS Access database.
• Do I need all facilities nationwide or just a particular geographic region or industrial category?
     –– Limiting the scope of the dataset may help reduce the size of the dataset you are requesting.

Please contact waterloadings@epa.gov with any data requests.

EPA’s PCS and ICIS-NPDES databases both use Standard Industrial Classification (SIC) codes. ICIS-NPDES does allow authorized NPDES programs to track the industrial category for a NPDES facility using the North American Industry Classification System (NAICS), which is the system that replaced the SIC code system. Most NPDES programs still use the SIC codes to track the industrial category for a NPDES facility. Consequently, users should first conduct their searches of DMR data using SIC codes before using NAICS codes.

No. The Loading Tool does not collect information on water quality trading. This trading is a relatively new approach to achieve water quality goals more efficiently. Trading is based on the fact that sources in a watershed can face very different costs to control the same pollutant. Trading programs allow facilities facing higher pollution control costs to meet their regulatory obligations by purchasing environmentally equivalent (or superior) pollution reductions from another source at lower cost, thus achieving the same water quality improvement at lower overall cost.

ICIS-NPDES manages information related to water quality trading through trade partners, which are managed in connection to specific limits. The presence of an active trade partner allows adjusted DMR values reflecting the results of the trade to be entered for that limit. These adjusted DMR values allow EPA, states, and the public identify whether a facility that does water quality trading is in compliance with its NPDES permit. The main purpose for these adjusted DMR values is to assess whether the permitted facility is in compliance with its permit. The Loading Tool does not use these adjusted DMR values in the EZ Search results. The results from EZ Search (DMR) are meant to provide estimates of who is discharging what pollutants in a specified area.

The Advanced Search output provides a comparison of the DMR value to the permit limit. This comparison is called "Load-Over-Limit" and is calculated two ways in the tool: 1) Load-Over-Limit Option 1 only shows the amount (mass) of the DMR value that exceeds the permit limit. DMR values that are below the limit are set to zero. 2) Load-Over-Limit Option 2 shows the mass of the DMR value that is above or below the permit limit. Option 2 allows users to see how much the DMR value is below the limit, while Option 1 only provides information on exceedances. Both of these options are presented in the Advanced Search output.

The current TRI toxic chemical list contains 593 individually listed chemicals and 30 chemical categories (including 3 delimited categories containing 62 chemicals). If the members of the three delimited categories are counted as separate chemicals then the total number of chemicals and chemical categories is 682 (i.e., 593 + 27 + 62). TRI reporters are not required to report releases for chemicals that are not on this list of 682 chemicals. Consequently, the TRI Search does not provide wastewater pollutant discharge estimates for pollutants that are not on this list of 682 chemicals. However, the EZ Search (DMR) and Advanced Search will likely have wastewater pollutant discharge estimates for pollutants not included in the TRI list of 682 chemicals (e.g., Total Suspended Solids).

As previously noted not all facilities report the same pollutants to the NPDES and TRI programs. These differences in pollutant reporting mean that there will likely not be a one-to-one match between pollutant discharges displayed by EZ Search (DMR) and TRI Search. For example, the TRI program focuses on toxic pollutant discharges and the NPDES program focuses on all aspects of water pollution. Consequently, the results of EZ Search (DMR) may show Total Suspended Solids (TSS) as the top pollutant discharge while the corresponding TRI search will not display any results for TSS (as TSS is not a toxic pollutant and is not reported under the TRI program).

Additionally, the universes of facilities that report under the NPDES and TRI programs do not overlap perfectly. For example, POTWs do not report under the TRI program. Consequently, the Loading Tool will have pollutant discharge data for a facility that reports monitoring data on DMRs and these data are imported into PCS and ICIS-NPDES even when the facility does not report under the TRI program. Conversely, the Loading Tool will have estimates of pollutant discharges to surface waters and POTWs for a TRI reporting facility even when the facility's DMR data is not in PCS or ICIS-NPDES.

The NPDES and TRI programs both require reporting of pollutant discharges; however, only the NPDES program requires wastewater sampling and reporting of these monitoring results to their permitting authority. While many TRI reporters base their TRI data on monitoring data, others report estimated data to TRI as the program does not mandate additional release monitoring. Various estimation techniques are used when monitoring data are not available, and EPA has published estimation guidance for the regulated community. Variations between facilities can result from the use of different estimation methodologies. These factors should be taken into account when considering data accuracy and comparability. See the following guide for considerations on how to use TRI data (PDF) (18 pp, 299K).

Another potential cause for a different between TRI and DMR data are errors in one or both of the databases. These errors may have originated with the reporting facility or, in the case of DMR data, with the state or EPA Region that entered these data into PCS or ICIS-NPDES. Finally, another potential difference might be that the DMR data are focused on point source releases (e.g., pipes, ditches, swales), while TRI releases include all releases to surface waters (including nonpoint source releases of TRI chemicals).

Yes. EPA may issue a civil administrative complaint to any person or company who violates the Emergency Planning and Community Right-to-Know Act (EPCRA), which is the main law supporting TRI reporting. The complaint may impose a civil penalty, including recovery of any economic benefit of non-compliance, and may also require correction of the violation. See the following page for more information on EPA's enforcement program for TRI reporting.

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 to FRS. Without this linkage it is not possible to connect these names of receiving waterbodies to other data sets as many waterbodies share their names with other waterbodies (e.g., there are 82 streams in the United States with the name “Pigeon Creek”). Likewise, there may be multiple ways of spelling a POTWs name and different POTWs can share the same name (e.g., there are three POTWs with the name “Middletown WWTP”). Consequently, it is not currently possible to accurately match TRI reporters to the receiving waterbody or identify in FRS the receiving POTW that is receiving their repoted TRI wastewater discharges.

There are differences in the way that the Loading Tool calculates loads over limit and exceedances, which can lead to inconsistent results:

• Load Over Limit The Loading Tool calculates loads by prioritizing average quantities/concentrations over maximum quantities/concentrations even if the permit limit is a maximum quantity/concentration. As a result, the measurement that the Loading Tool uses to calculate the pollutant load may not have the same statistical basis as the permit limit.
• Exceedances The Loading Tool measures exceedances by comparing the DMR measurement that directly corresponds to the permit limit (e.g., maximum concentration compared to maximum concentration limit).

Therefore, results for Load Over Limit searches may not directly match Exceedance Counts searches. For example, the load over limit calculation may compare a pollutant load calculated from an average concentration to the permit limit load calculated from a maximum concentration. If the average concentration-based load is less than the maximum permit limit-based load, then the load over limit will be zero. However, for Exceedance Counts, if the maximum concentration is greater than the maximum concentration limit, then the Loading Tool will flag the maximum concentration as an exceedance.

EZ Search (DMR) results tables include links to Enforcement Compliance Reports, Effluent Charts, and Water Quality Reports on EPA’s Enforcement and Compliance History Online (ECHO) Website:

• Enforcement Compliance Reports contain information summarizing compliance monitoring (5 year history), compliance status by quarter (3 year history), notices of violations (5 year history), and formal enforcement actions (5 year history).
• Effluent Charts plot the pollutant concentrations and quantities reported on facility DMRs and flag violations (3 year history).
• Water Quality Reports summarize watershed conditions, listed impairments and causes of impairment, and proximity of discharges to drinking water intakes.

Yes. When you navigate to a specific facility you will see a blue “C” icon, which is a link to the ECHO Detailed Facility Report. This report will show compliance history over the last three years.

You can also navigate to ECHO, select “Water Data Search” on the left hand side bar, and choose a retrieval tool based on your state (there are currently two separate water databases, PCS and ICIS-NPDES). Users can then search based on ZIP code, city, or other area of interest. The output from your searches can be displayed on a map.

Finally, you can use the following searches on the Everyday Searches tab to identify instances of limit exceedances:

• Exceedance Charts. Search by geographic location, pollutant (required), and/or industry to visually compare the number and magnitude of exceedances over multiple years.
• Load Over Limit Summary. Search by year, geographic location, and/or industry to generate a data file showing facility information, the total facility load over limit, top load over limit parameter, and the parameter load over limit for each reporting year.
• Facility Exceedance Counts. Search by facility and monitoring period range to generate counts of exceedances for each type of effluent limit (e.g., maximum concentration, average concentration), for each pollutant, at each outfall at the facility.

There are several sources of information. Please use the resources below.

• EPA Annual Accomplishments Report
• EPA Annual Results Statistics
• EPA Information about CWA Priority Areas
• Access EPA Case and Press Release Search
• ECHO‘s Enforcement Data search provides data about EPA cases taken under the CWA

In order to limit your case search to cases related to Clean Water Act compliance, scroll to the “Case Attributes” section of the ICIS Enforcement Data (EPA Cases) Search, and select “CWA - Clean Water Act” from the “Primary Law” drop down menu.

EPA will add loading data to existing ECHO searches and features. These enhancements will be developed in early 2012.

No. The Loading Tool does give information on the receiving waterbody and whether a watershed pollution budget plan is needed (TMDL).

EPA makes available information about water quality that EPA receives from states on its EnviroMappper for Water. You can also view watershed monitoring reports that states submit to EPA on a two year cycle.

EPA verified the accuracy of the calculations. Section 5 of the Technical Users Background Document for the DMR Pollutant Loading Tool (PDF) (143 pp, 2.4MB) describes procedures that EPA used to verify the accuracy of the Loading Tool calculations.

EPA also conducted a preliminary review of the Loading Tool output to investigate the accuracy of the underlying DMR data used for the calculations. EPA identified and corrected a number of data errors. However, additional data errors may exist because EPA’s review focused on the highest discharges and included only a limited number of facilities. If users identify errors in the underlying DMR data, they can submit comments to EPA’s Integrated Error Correction Process.

The Loading Tool generates its output using annual data extracts from its compliance databases (PCS and ICIS-NPDES) and TRI. EPA has verified the accuracy of the TRI data used by the Loading Tool and the Loading Tool’s calculations using DMR data, and has conducted a preliminary review of the tool output to verify the accuracy of the underlying DMR data used for the calculations. However, EPA‘s review of the underlying data has focused on the highest discharges and included a limited number of facilities. EPA is unable to identify and correct all the errors in the PCS and ICIS-NPDES databases.

You can help improve data quality by following the step-by-step instructions on how to report errors to EPA. Once you submit an error report, it will be entered into EPA’s Integrated Error Correction Process. You will receive an immediate acknowledgement, and status updates as EPA determines how to address the error report.

A general rule of thumb is that users should more carefully review pollutant discharges from “non-major” facilities if the annual pollutant discharge for any one pollutant for any one facility exceeds 9 million pounds. As noted above the average “non-major” facility typically has a discharge flow that is less than an average “major” facility. A very large “major” sewage treatment plant can discharge 100 million gallons of wastewater per day or more. A value of 9 million pounds of annual discharge roughly translates to a facility discharging 100 million gallons of wastewater per day, 365 days per year, at a pollutant concentration of 30 mg/L. You can use the Advanced Search to review each set of monitoring data or the link to “Effluent Charts” to identify potential errors.

As described below, the results of EZ Search (DMR) are also flagged if there is a potential outlier.

You can send suggested corrections to non-DMR data to to the waterloadings@epa.gov (please include: “Error Correction” in the subject line). Any suggested error corrections regarding DMR and TRI data that are sent to waterloadings@epa.gov will be returned to the send with the correct error correction submission process (see previous question).

EPA plans to add more recent DMR and TRI data each year. EPA plans to update the Loading Tool database monthly to incorporate any error corrections.