How to Read Your Monthly Operating Report

A monthly operating report is the state's month-end picture of how the plant and the distribution system actually ran. Operators shorten it to MOR, or monthly report. It is not a Consumer Confidence Report, and it is not a public notice. It is the form the primacy agency uses to see disinfectant residual, production, chemical feed, and, if you filter, turbidity, for the month that just closed.

There is no single national MOR and no national due date. States write the form, name the lines you must fill, and set the day the form is due. Confirm both with your primacy agency. Wyoming, the District of Columbia, and tribal systems ask the EPA region with primacy. This isn't legal advice.

What the form is, and what it is not

The monthly operating report is a primacy-agency document. Some states call it a monthly report or an electronic worksheet. Community systems, non-transient systems, and some transient systems can all owe a version of it. Surface-water plants almost always do. Many groundwater systems that disinfect do too. Ask. Do not assume a well system with no filter is exempt.

It is not the official monitoring schedule. Ask for that schedule with the PWSID: How to request your state monitoring schedule. A complete MOR with a missed VOC period is still a missed VOC period. It is not the annual CCR. Do not wait for July 1 to notice a blank residual line from March. This page does not restage the CCR posts. Inspectors do read MORs; a year of blank residual rows is a finding waiting for the next letter. See How to read your sanitary survey letter.

Read the header before you argue a number

Open the form the state actually uses, not a copy you inherited from a prior operator. Confirm:

• PWSID, system name, and month. A name-only header is how last month's residual lands on someone else's file. If you need the identifier, use PWSID lookup.
• System type and source. Community or non-community, ground water or surface water, purchased or own source. The lines you owe change with that classification.
• Which plant or entry point the page covers. Consecutive systems and systems with more than one plant often owe more than one page. See consecutive and purchased-water obligations.
• The due date printed on this year's instructions. Do not reuse a date you remember from a different state or from a training slide. If the instructions do not print a date, ask the primacy contact and write the answer on the folder.

If the form is electronic, save the submitted file the same day. Portals overwrite.

Disinfectant residual is two edges, and the MOR is where they show

If you disinfect, residual is a floor you must hold and a ceiling you must not cross. The federal numbers live on Chlorine residual and the disinfectant MRDL. This page is how those readings look on the monthly form.

Typical residual rows, depending on the state form:

• Entry-point residual, often a daily minimum. 40 CFR 141.72 is the federal floor that matters here: the residual entering the distribution system cannot fall below 0.2 mg/L for more than four hours, when that requirement applies to you. A day you left blank is not a day the state will treat as "probably fine."
• Distribution residuals at the sites the state named. A dead-end main that reads undetectable is a citable problem, not a nuisance. If more than 5 percent of distribution samples in a month are undetectable, and that happens two months in a row, you are in the federal failure the residual page already describes.
• Chlorine, chloramine, or chlorine dioxide, whichever you actually feed. Do not log free chlorine on a chloramine month. The MRDL is 4.0 mg/L for chlorine and for chloramine, and 0.8 mg/L for chlorine dioxide, as running annual averages under 40 CFR 141.65. The MOR is often where that average is built.

Read the residual block for blanks and for a day the plant ran but the cell is empty. The form is what the state will quote.

Turbidity, if you filter

If you treat surface water, or groundwater under the direct influence of surface water, the turbidity lines are a treatment-technique record, not an aesthetic note. The numbers you are held to depend on the filter type and on whether you have a filtration-avoidance waiver. That framework lives on Turbidity in drinking water, NTU, and the treatment technique. On the MOR, you are looking for three things:

• The daily (or continuous) readings the state asked for, not a once-a-month grab you took because the bench was free.
• Whether the month met the 95-percent test that applies to your filtration type. Conventional and direct filtration are held to 0.3 NTU or less in at least 95 percent of monthly samples, and never above 1 NTU, under 40 CFR 141.73. Slow sand and diatomaceous earth have a different pair of numbers. Use the pair that matches your plant, not the pair from a training plant you visited.
• Any spike, even if the rest of the month was clean. A storm-day exceedance is still an exceedance. The turbidity page explains what that can trigger. The MOR is how the state sees that it happened.

If your form asks for a turbidity reading, fill what it asks. Do not leave it blank because you think the rule does not apply. Ask the primacy contact whether that line is required for your classification.

What a blank or late line becomes

A blank required line is not a neutral cell. In most primacy programs it becomes a reporting or monitoring violation for that period: you either did not measure what the state required, or you measured it and did not report it. The public-notice path for a reporting or monitoring violation is usually Tier 3. Confirm the tier with the state. The clock and the write live on other pages. This page is only the finding that starts them.

A late form is the same family of problem. Filing March in May is how a clean residual month still lands as a reporting violation. If the portal was down, keep the time you tried and tell the primacy contact the same day. Send the missing month as its own filing.

Keep the bench sheets with the filed form. If a meter failed, write that on the form the way the state allows. Silence on a required line is what turns into the violation.

If the state records a reporting violation for a blank or late MOR, filing the missing form is usually the start of closeout, not the closeout itself. See How to close an open SDWIS violation.

Keep a copy with the PWSID

Save the submitted MOR the day you file it. Put the PWSID on the filename. Keep it with the bench sheets and the residual log. 40 CFR 141.33 is the federal retention floor; use the longer of that floor and the state's MOR instructions. See water system record retention.

The day the month closes: walk every required line, match the form to the bench sheets, and file on the state's clock. Save the copy with the PWSID. If a residual floor, an MRDL, or a turbidity number was missed, call the primacy contact.

FAQ

Is there a federal due date for the monthly operating report?

No. The form and the due date are state (or EPA-region) requirements. Confirm both with your primacy agency. Do not use another state's date, and do not use a date from a training handout.

We do not filter. Do we still file an MOR?

Many groundwater systems that disinfect still file a monthly report for residual, production, and chemical feed. Some transient systems file a shorter form. Ask. A "we don't filter" assumption is how a residual month never gets reported.

Check my system at /find-my-system.

Orevant provides compliance information tools. This page isn't legal advice. Confirm the monthly operating report form, the required lines, and the due date with your primacy agency.