The DMR filing process requires every NPDES permit holder to measure the pollutants their permit lists, enter those results into the EPA’s NetDMR system on the schedule the permit sets, and have an authorized signatory electronically sign and submit the report, typically by the 28th of the month after the monitoring period ends. Each submitted Discharge Monitoring Report becomes part of a permanent, publicly searchable federal record, and mistakes carry civil penalties reaching tens of thousands of dollars per day.
Who Has to File
The Clean Water Act prohibits discharging pollutants from a point source into U.S. waters without an NPDES permit,1US EPA. NPDES Permit Basics and every holder of that permit must report monitoring results at the intervals the permit specifies.2eCFR. 40 CFR 122.41 – Conditions Applicable to All Permits That covers industrial plants, municipal wastewater treatment facilities, and commercial operations discharging directly to surface waters. Size affects how closely regulators watch you, but not whether you file.
What the Report Has to Contain
A DMR covers one monitoring period, usually a calendar month. The permit tells you which parameters to measure, how often to sample, and which units to report in. Common parameters include pH, biochemical oxygen demand, total suspended solids, and flow volume, and industrial permits typically add pollutants specific to that industry.3US EPA. Module 11 – USEPA NPDES WET Limits, Monitoring Requirements and Reporting in ICIS-NPDES
Preparing the report means gathering lab results from each sampling event and entering those values in the fields that correspond to the permit’s parameters, using the units and reporting limits the permit defines. Cross-check every entry against the underlying lab report before you submit. NetDMR runs automated validation and flags inconsistencies, but catching transcription errors on your side avoids compliance alerts you’ll then have to explain.
Filling Blanks With No Data Indicator Codes
When you don’t have a numeric result for a required parameter, you can’t leave the field empty. You enter a No Data Indicator (NODI) code that tells the regulator why the value is missing.4US EPA. EPA DMR NODI Codes Picking the right one matters, because each code says something different about your facility. The codes filers hit most often:
- C — No Discharge: the facility had no discharge during the monitoring period.
- B — Below Detection Limit: the lab analyzed the sample but the pollutant was not detected.
- E — Failed to Sample: the required sampling or analysis was not conducted.
- 9 — Conditional Monitoring Not Required: a conditional monitoring requirement didn’t apply that period.
- G — Sampling Equipment Failure: a malfunction prevented sampling.
- K — Natural Disaster: a natural disaster made monitoring impossible.
Code E draws the most scrutiny because it signals that required monitoring simply didn’t happen. Using it repeatedly is a red flag. When you genuinely could not sample, document the circumstances thoroughly in your facility records so you can explain the entry later.
Submitting Through NetDMR
Since December 21, 2016, most NPDES permit holders have had to file DMRs electronically through NetDMR rather than on paper. The EPA can grant temporary waivers for episodic situations, but only for 60 days at a time, and no waiver can extend beyond December 21, 2028.5eCFR. 40 CFR Part 127 – NPDES Electronic Reporting
Once your monitoring data is entered, NetDMR runs an automated validation check and flags potential errors or missing fields. Everything the system flags must be corrected before the submission can go forward. When validation clears, the authorized signatory applies an electronic signature under the Cross-Media Electronic Reporting Rule, which gives that digital signature the same legal weight as a handwritten one.6US EPA. Cross-Media Electronic Reporting Rule (CROMERR) After the signatory clicks final submit, the system generates a Copy of Record with a unique transmission ID. Save it. That document is your official proof of filing.
Setting Up the Signatory and Permit Administrator
NetDMR access is role-based. Two roles drive the filing:
- Signatory: the person with authority to sign and submit DMRs for the organization. This person must execute a subscriber agreement before signing privileges take effect.
- Permit Administrator: manages access to the permit inside NetDMR, approving or denying requests from data providers and other users to view or edit DMR data.
Before a signatory can submit anything, they have to complete an identity verification process and sign either an Electronic Signature Agreement or a paper subscriber agreement. The electronic route typically runs through a third-party identity-proofing service. The paper route means printing, signing, and mailing a physical document to the regulatory authority for approval. Requirements vary by state, so confirm with your permitting authority which process applies before you plan around a deadline.
When the DMR Is Due
Most NPDES permits set the submission deadline at the 28th day of the month following the end of the monitoring period. A DMR covering January sampling is due by February 28. Some permits require quarterly or annual reporting instead of monthly, depending on the type and volume of discharge. Read your own permit for the schedule that applies to you.
These deadlines are firm. A late submission is treated as a reporting violation, and the agency sees non-receipt status in real time through its compliance tracking systems.
Reporting Bypasses and Upsets Separately
A DMR reports numbers. When something goes wrong at the facility, a separate notification obligation kicks in on top of the DMR, and federal regulations treat two situations differently.7eCFR. 40 CFR 122.41 – Conditions Applicable to All Permits
A bypass is when wastewater intentionally skips part or all of a treatment process. If you know about one in advance, you must notify the regulatory agency at least ten days ahead when possible. An unanticipated bypass requires 24-hour notice. A bypass is prohibited unless all three conditions apply: it was unavoidable to prevent loss of life, personal injury, or severe property damage; no feasible alternatives existed; and the facility submitted proper notice.7eCFR. 40 CFR 122.41 – Conditions Applicable to All Permits
An upset is an unintentional, temporary failure to meet permit limits caused by factors beyond reasonable control. To use it as a defense in an enforcement proceeding, you have to identify the cause, show the facility was being properly operated at the time, and submit 24-hour notice. The burden of proof sits with the facility. Noncompliance from poor maintenance, operational error, or inadequate treatment capacity does not qualify as an upset.7eCFR. 40 CFR 122.41 – Conditions Applicable to All Permits
Records You Have to Keep After Filing
Filing the DMR isn’t the end of the paperwork. Facilities must keep all monitoring records, calibration logs, original strip chart recordings, and copies of submitted reports for at least three years from the date of the sample or report.2eCFR. 40 CFR 122.41 – Conditions Applicable to All Permits Records related to sewage sludge use and disposal carry a longer minimum of five years.7eCFR. 40 CFR 122.41 – Conditions Applicable to All Permits The regulatory agency can extend either retention period at any time simply by asking.
Inspectors may arrive unannounced to review the archive. Keep lab reports, chain-of-custody forms, and calibration records organized so any individual sampling event can be traced from the field to the final DMR entry. That traceability is what auditors check.
What Errors and Late Filings Cost
Civil penalties for permit violations, including filing inaccurate DMRs, can reach $68,445 per day per violation after the most recent inflation adjustment.8GovInfo. Federal Register – Civil Monetary Penalty Inflation Adjustment Rule 2025 The statutory base of $25,000 per day rises over time under the Federal Civil Penalties Inflation Adjustment Act.9Office of the Law Revision Counsel. 33 USC 1319 – Enforcement
Criminal exposure scales with intent. Negligent violations run $2,500 to $25,000 per day and up to one year in prison. Knowing violations run $5,000 to $50,000 per day and up to three years. False statements in a report or tampering with monitoring equipment carry fines up to $10,000 and up to two years in prison, with second convictions doubling the maximums.9Office of the Law Revision Counsel. 33 USC 1319 – Enforcement
The falsification provision reaches further than most filers realize. It covers not only fabricated lab results but any false statement in a report, application, or plan required under the Clean Water Act. Signing a DMR while knowing the data is inaccurate creates individual criminal exposure for the signer, regardless of whether the discharge harmed the environment.
Every DMR you submit also feeds the EPA’s Enforcement and Compliance History Online (ECHO) database, which is freely searchable by anyone.10Enforcement and Compliance History Online. ECHO Home Page Environmental groups, journalists, downstream communities, and potential business partners use it to evaluate facilities. A pattern of late filings, missing data, or exceedances shows up in the public record long before any formal penalty is assessed, and often carries reputational consequences that outlast the compliance issue itself.