Effluent Charts Help

The Effluent Charts page presents dynamic charts and tables of permitted effluent limits, releases, and violations over time for Clean Water Act (CWA) wastewater discharge permits issued under the National Pollutant Discharge Elimination System (NPDES). Note: Information about NPDES discharge measurement is available under "CWA/NPDES Compliance Status" in the Detailed Facility Report Data Dictionary.

Here you can find help with the following topics:

Accessing Effluent Charts

There are two ways to access effluent charts:

  1. From Facility Search Results (All Data, Water, and Hazardous Waste Searches)

Facilities with Effluent Charts available have an "E"  icon in the Reports column of the Results table. An "E" icon indicates that one set (i.e., one NPDES permit ID) of charts is available. Clicking the "E" icon opens the Effluent Charts page in a new tab.

  1. From the Detailed Facility Report

The Three Year Compliance Status by Quarter table in the Enforcement and Compliance section of the Detailed Facility Report provides CWA compliance status information by pollutant (violations only). Clicking the hyperlinked pollutant name opens a new tab with pollutant-specific effluent charts available for selection. The Effluent Charts page pre-selects and loads the charts for the specified pollutant. From this page you can choose to view a different chart set for any pollutant monitored at the facility.

Navigating Effluent Charts

Summary Matrix

The top of the Effluent Charts page displays a chart summary that allows you to further refine the universe of effluent data presented. You can specify a date range of interest, as well as select (or deselect by clicking) one or more of the following compliance status values of interest:

  • Red - Significant Non-Compliance
  • Yellow - In Violation
  • Blue - No Violations
  • Gray - Unknown

By default, data representing the current compliance status for each pollutant/outfall combination is presented. You can toggle this setting to instead view data by overall compliance status. Your selections control the display of the summary matrix of pollutants discharged at a facility by individual outfalls. The summary matrix provides both a quick, high-level view for the facility, as well as a means to select a pollutant/outfall of interest to graphically view effluent data.

Click on any cell in the matrix to display concentration and quantity charts for the selected pollutant/outfall combination. The charts are displayed on the same page below the summary matrix. There are three ways to view multiple charts at one time:

  1. Selecting the left-most cell in the All Outfalls column in a chemical row in the summary matrix displays charts for all outfalls where the selected pollutant is monitored.
  2. Selecting a cell from the All Chemicals row (bottom row on the matrix) displays charts for all pollutants monitored at the selected outfall.
  3. Selecting the intersection cell for All Outfalls and All Chemicals displays all charts for the facility for the specified NPDES ID.

Chart Data

Each effluent chart displays all of the effluent measures, permitted limits, and effluent violations for the given dates, for a single permit, discharge point, parameter, monitoring location, and sampling period. The charts show different violation data for ICIS-NPDES permits, reflecting the different information stored about violations in those systems.

Basic chart information is displayed in the chart header, including:

  • Discharge Point: 3- or 4-character code that uniquely identifies a single permitted discharge point (also called a pipe or outfall).
  • Parameter: The pollutant measured.
  • Monitoring Location: Describes the location at which sampling for the parameter occurred (e.g., effluent gross)

Two effluent charts are available for each pollutant and discharge point at a facility:

  1. Concentration Chart: Displays the maximum, average, and minimum concentration measurements and effluent limits.
  2. Quantity Chart: Displays the maximum, average, and total quantity measurements and effluent limits.

Each chart measurement is placed into one of three possible statistical categories:

  • Maximum (concentration or quantity)
  • Average (concentration or quantity)
  • Minimum (concentration only) or Total (quantity only)

By default, the charts present data for the past three years on a monthly scale. The chart symbols identify the measurement's statistical basis (i.e., maximum, average, minimum or total) and change color if the measurement is in violation of the effluent limit. The Water Compliance Status section of the Detailed Facility Report Data Dictionary defines the CWA violation categories. A timeline at the top of the chart flags time periods when the facility is in violation of its reporting requirements. The violation flag icons identify the corresponding statistical basis associated with the reporting violation. 

Chart Legend

Interacting with Charts

Effluent charts are interactive. Useful features include:

  • Data Point Value: Hover your mouse pointer over any data point or limit line to view an attribute bubble containing the measurement or limit value.
  • Data Series Displayed: Use the chart legend shown below the chart to control which data series are shown on the chart. Click to enable (or disable) data series displayed.
  • Zoom: Using your mouse pointer, drag out a rectangle in the chart. The chart will adjust to zoom into the selected area. Click "Reset zoom" to return to the default chart view.
  • Download Chart: Click the "Download Chart" button in the upper-right corner of the chart to print or download the current view of the effluent chart. Select from one of the following options:
    • Print Chart
    • Download PNG image
    • Download JPEG image
    • Download PDF document
    • Download SVG vector image

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View Chart Data in a Table

Effluent chart data are also available to view in a tabular format. Click the "Show/Hide Table" button to display a detailed data table below the chart. Use the vertical and horizontal scrollbars to view data. Sort columns by clicking on the column heading. The Data Dictionary describes the contents of effluent data tables and downloads.

Reporting Errors

If you believe that some of the information in an effluent chart or table is in error, you may report your findings from the Effluent Charts page. Click the "Report an Error" button at the top of the page and a "Report an Error" button will appear above each chart. Click "Report an Error" for the chart where you believe the error is to open an error reporting form for that chart.

The error reporting form will ask for your contact information, in order to keep you informed of progress in addressing your report, and a description of the problem. Please include enough information to allow EPA to identify the data in question and to evaluate your comment.

Once you submit the report, it will be entered into EPA's  Integrated Error Correction Process. You will receive an immediate acknowledgement on the webpage, and status updates as EPA determines how to address the report (see Error Correction Performance Standards).

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Data Considerations

The CWA Effluent Charts only show effluent data and violations, and compliance schedule violations (late or missing discharge monitoring reports (DMRs)). They do not show single-event violations (or other types of permit violations, often the result of inspection findings).

Under certain circumstances, Effluent Charts may appear to be missing effluent, limit, or violation data. There are several reasons for this apparent lack of information, which may be broken into the following cases:

  • Numeric limits are present without measurement data or violations
    This can occur in some cases for non-major permits. Without this functionality, missing measurements will not result in violations.

  • Effluent measurements are present without corresponding numeric limits.
     This may reflect a condition where "monitoring only" is either optional or required.

  • No limit or measurement data are shown for a specific time period. 
    Lack of limit or measurement data may be due to seasonal limits or optional monitoring. Lack of measurement data for required monitoring will generate violations, unless DMR non-receipt tracking is turned off.

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Data Dictionary

This section describes the format and contents of the Effluent Charts data table and data download. For more information about CWA/NPDES discharge measurements, please see the Detailed Facility Report Data Dictionary.

Table 1 below lists the data fields that are displayed for the Effluent Charts data table.

Table 1: Effluent Charts Data Table
Column NameDescription
DateThe end date of the reporting period.
Statistical Base Type
Statistical type of the permitted limit. “MIN”, “AVG”, “MAX” or “TTL” indicate that the smallest, average, largest, or total of the sample measurements taken within a reporting period have numerical limits and must be reported.
Value QualifierMay be "<" or ">" to indicate that the reported value is an upper or lower bound, respectively, on the true value. This field is usually "=" to indicate the true value.
Measured ValueReported value of the parameter. Units are provided in the column name.
LimitValue of the permitted limit for this parameter. Units are provided in the column name.
Violation Severity*Severity of any alleged violation caused by the reported value:

  • SNC - significant noncompliance
  • RNC - reportable noncompliance
  • Effluent - effluent violation, i.e. discharge in excess of permitted limit
  • Mon/Rpt - monitoring or reporting violation
  • No Violation or (blank) - no violation
Violation Type*
Text description of the code value for Violation Code.
Violation Code*
Code that describes the type of an alleged effluent or monitoring/reporting violation:
  • E90 - effluent violation
  • D90 - Discharge monitoring report (DMR) overdue, with a numeric limit
  • D80 - DMR overdue, monitoring only required
Other codes exist but are rarely used.
RNC Resolution Type*
The facility has returned to compliance with its permit conditions. RNC Resolution Type describes the resolution of the reportable noncompliance event:
  • NC - Manual Unresolved RNC
  • RE - Manual by EPA/State/Tribal Action
  • NC - Unresolved RNC
  • RE - Back into Compliance
  • RP - Due to Formal Enforcement Action Final Order with Compliance Schedule
  • RP - In Compliance with Formal Enforcement Action Final Order Requirement
  • RE - Resolved RP by NPDES Closure of Enforcement Action Final Order with Compliance Schedule
  • RE - Manual Resolution by Enforcement Action
  • RP - Manual RP - In Compliance with Formal Enforcement Action Order Requirement
  • RP - Manual Due to Formal Enforcement Action Formal Order
  • RE - Manual by Back into Compliance
* Repeating value: Each "set" of violation data occurs once for each reported value (concentration and quantity). The repeated values describe the up to three concentration-based limits and two quantity- or mass-based limits that can be established in a permit for each pipe, parameter, monitoring location, and period. These data are only populated for permits from ICIS-NPDES.


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