How to Handle a Missed Monitoring Period

A missed monitoring period is a monitoring or reporting violation the hour the window closes without a valid sample. It is not an MCL. It still has a notify-the-state job, a make-up sample, and a public-notice path. The usual federal path is Tier 3 under 40 CFR 141.204, unless the rule or the primacy agency puts that miss in a tighter tier.

This page is what to do the day you find the miss. It is not how to get the official schedule: How to request your state monitoring schedule. It is not the federal IOC list: Inorganic contaminants, the IOC MCL list, and the monitoring framework. Confirm the make-up site, the hold time, and the notice tier with your primacy agency. This isn't legal advice.

The day you find the miss

Do these in order. Do not wait for the next scheduled window to "catch up."

• Write down what was missed. Contaminant group (VOC, IOC, SOC, DBP, nitrate or nitrite, radionuclides, asbestos, lead and copper, coliform, or a state-only group), the compliance period, the site ID, and the date you discovered the gap. Put the PWSID on that note.
• Notify the primacy agency the same day. Email or portal the monitoring desk or the district inspector. Say what was missed, the period, the site, and that you are arranging a make-up sample. Ask whether they want a specific site, a specific method, or a tighter public-notice clock than the federal default. Wyoming systems notify EPA Region 8. The District of Columbia and tribal systems notify the EPA region with primacy.
• Take the make-up sample as soon as the lab can kit it, at the site the state names. A make-up does not erase the miss. It limits how long you operate without a result, and it is often what the state requires before they will talk about returning to compliance.
• Start the public-notice path for a monitoring or reporting violation. Do not wait for a formal notice of violation to begin the calendar. The violation exists when the period closed without a valid sample.

If you do not have the current official schedule in hand, ask for it in the same email. Public SDWIS views lag. Do not decide "we didn't really owe that bottle" off an ECHO screen. See How to read your SDWIS violation record.

Make-up sampling that counts

Call a state-certified drinking-water lab, not a wastewater bench or a clinic. Method, bottle, preservative, and holding time have to match the contaminant group. That lab choice is a different page: How to choose a state-certified drinking water lab.

• Site. Use the entry point, well, or distribution site on the official schedule. If the schedule is silent, ask. A hose bib you like is not a make-up site.
• Method and holding time. VOCs and some SOCs die in a warm cooler. Nitrate has a short hold. DBPs have designated sites and a sample type (standing vs flushed) the rule already set. If the make-up bottle is rejected, you still have a miss plus a wasted week.
• Paper. Put the PWSID, the site ID, the missed period, and the words "make-up for missed [group] [period]" on the chain of custody so the state can match the result to the violation.
• Do not skip the next routine sample because you just took a make-up. The make-up is for the period you missed. The next window is still due.

If the miss was a repeat coliform, a confirmation nitrate, or a triggered source sample, you are not in a routine make-up. Those have their own short clocks. Treat them as the rule that created them, not as a generic annual IOC.

Public notice for a monitoring or reporting violation

40 CFR 141.204 puts most monitoring violations in Tier 3, except where 141.202 requires Tier 1 or the primacy agency requires Tier 2. Tier 3 means:

• Notice to persons served no later than one year after the system learns of the violation.
• Repeat annually if the violation is still open.
• If you post, leave it up for as long as the situation lasts, and for at least seven days.
• Community systems may use the Consumer Confidence Report as the Tier 3 vehicle when the CCR meets the content and delivery rules and actually goes out inside that year. See how to deliver and certify your CCR.
• You still owe the ten content elements in 40 CFR 141.205, including the standard monitoring-violation health-effects language in 141.205(d)(2). Use the state's template.
• Certify to the state within 10 days after you complete the notice, with a copy of each type of notice, under 40 CFR 141.31(d).

The one-year federal default is a ceiling, not a target. Many states want the notice sooner, or they want it mailed even when you also put it in the CCR. Ask in the same email that reports the miss. The tier table itself is here: SDWA public notice tiers.

Nitrate and nitrite missed monitoring can be tighter

Routine failure to monitor for nitrate or nitrite is still listed as a monitoring violation, and EPA's own failure-to-monitor templates treat that miss as a public-notice event. Some primacy agencies keep it in Tier 3. Some elevate it. Confirm the tier and the deadline with the state the day you find a missed nitrate or nitrite period. Do not assume you have a year.

Two related events are not "missed routine monitoring" and are already Tier 1 under 141.202:

• A nitrate, nitrite, or combined nitrate-and-nitrite MCL.
• Failure to take a confirmation sample within 24 hours after you learn that the first sample exceeded the nitrate or nitrite MCL.

Those write-ups are not this page. Start here for the MCL notice: nitrate violation public notice. If you missed a confirmation bottle, you are on the 24-hour track, not the Tier 3 track.

What this miss is not

• It is not an automatic civil-penalty number. Do not invent one. The state decides whether the miss becomes informal follow-up, a formal order, or a returned-to-compliance line after the make-up and the notice. Ask what they want in writing.
• It is not permission to skip the next period.
• It is not a waiver. If you think the group should not have been on the schedule, request a written schedule correction or a waiver. Sampling first is cheaper than arguing after the window closes. See how to request a monitoring waiver.
• It is not a public SDWIS glitch you can ignore. If the state file says you owed the sample, treat that as the assignment until they say otherwise in writing.

How you keep this from happening again

• Get the current official schedule by PWSID and put every line on the operator calendar the same week. Ask again after a source change, a treatment change, a population jump, or a waiver that expires.
• Call the lab two windows ahead, not two days ahead. Holding times and bottle kits are the lab's job. The due date is yours.
• When a result is rejected (broken bottle, expired hold, wrong preservative), treat that as a miss-in-progress and resample inside the period if it is still open.
• Keep the schedule, the chain-of-custody, and the state reply together. That packet is what you show when someone asks which period you were on.

FAQ

If I take the make-up sample this week, do I still have a violation?

Usually yes. The violation is the missed period. The make-up is what you do next. The state may return you to compliance after it has the result and the public notice. It does not rewrite the calendar. Report the make-up as a make-up, and still do the notice the state requires.

Can I put every missed-monitoring notice in the CCR and be done?

For many Tier 3 monitoring violations, yes, if the CCR carries the required elements, goes to all persons served on time, and the state accepts that method. Ask first. Some states want a separate mailed or posted notice, and nitrate or nitrite misses are the ones they most often pull out of the annual report.

The public ECHO page does not show the miss yet. Should I wait?

No. ECHO lags. The official schedule and the state's file are what you act on. Waiting for a public extract is how a one-period miss becomes two.

We missed VOCs and nitrate in the same year. One notice or two?

You can often combine Tier 3 monitoring violations in one notice or in the CCR if every required element is there for each group. Confirm with the state. If either miss has been elevated to Tier 2 or Tier 1, that one gets its own clock and cannot wait for the annual report.

Check my system at /find-my-system.

Orevant provides compliance information tools. This page isn't legal advice. Confirm the missed period, the make-up sample, and the public-notice tier with your primacy agency.