NPDES Monitoring Data Download Help

The NPDES Monitoring Data Download provides an easy-to-read file for all available permit limit and discharge information for facilities regulated under the CWA National Pollution Discharge Elimination System (NPDES) in a downloadable spreadsheet format (XLSX) or CSV file. The files organize NPDES pollutant permit limits and associated discharge monitoring data in tables by outfall for a single facility within a selected date range.

Search Criteria Help

Monitoring Period Date Range

Select the time period (month and year) for the permit limit and reported discharge data. Dates available for selection are January 2007 to present. Note that depending on when the permit became effective, a permit may not have data for all or part of the selected time period.


Search for one NPDES permit at a time. A nine-character code, starting with the 2-letter state abbreviation, used to uniquely identify a permitted NPDES facility in EPA's program system. The NPDES permit program regulates the direct discharge of pollutants into U.S. waters.

Note that the EPA NPDES ID may be different than the state NPDES ID for a facility. If you do not know the EPA NPDES ID, use the quick search on the ECHO homepage to search for the facility and its program IDs.

Download File Structure

The spreadsheet format follows a repeating structure, with each table defined uniquely by the outfall, monitoring location, and limit set.

Each column in the table contains the time series of pollutant measurements, or Discharge Monitoring Reports (DMRs), taken at the outfall and monitoring location applicable to the limit set. The column header includes the following information:

  • Parameter name, e.g., "Solids, suspended percent removal"
  • Permit limit type, value, and units.
  • Statistical basis of the measurement (statistical base code), e.g., Daily MX = Daily Maximum, and DMR Value type.

Each row corresponds to one monitoring period. The table cells display the reported measurement value or No Data Indicator (NODI) code.

A blank cell within the table indicates that no measurements were reported for the parameter at the applicable outfall, monitoring location, and limit set during the monitoring period.

Data Dictionary

Outfall/Permit Feature ID

A three-character code in ICIS-NPDES that identifies the point of discharge (e.g., outfall) for a facility. A NPDES permit may have multiple points of discharge.

Monitoring Location

A single-character code in ICIS-NPDES that indicates the sampling location for each pollutant measurement.

Limit Set

A single-character code in ICIS-NPDES that groups limits that are set on a similar basis (e.g., monthly vs. annual limits, seasonal limits)


The name of the parameter in ICIS-NPDES.

Limit Type 

The unique code that indicates whether a limit is an enforceable limit (ENF) or a benchmark threshold (ALR). Benchmark thresholds do not receive effluent violations.

Limit Value (Unit)

The numeric limit and units from the Permit or Enforcement Action Final Order. If this value is blank or null, the DMR has report-only monitoring (i.e., no limit, alert, benchmark, or threshold value).

Statistical Base

The code representing the unit of measure applicable to the limit and DMR values (e.g., 30-day average, daily maximum). For a list of all codes and descriptions, download the Statistical Base Code Reference Table (CSV).

DMR Value Type

Indicates whether the DMR data are reported as concentrations (C1, C2, or C3) or quantities (Q1 or Q2).

No Data Indicator (NODI)

The unique code in ICIS-NPDES indicating why no DMR value was submitted by the permittee. Refer to the Loading Tool Glossary for a list of NODI codes and descriptions.