NDMA was in Wichita Falls drinking water in 2009.
Five years before a drop of treated wastewater entered the drinking water supply.
These results were collected under a federal monitoring program, analyzed by an EPA method, and published by EPA. They are not my measurements, not the City's measurements, and not in dispute. They are the baseline against which everything that came afterward should be read.
Federal NDMA monitoring results, 2009
| Sample date | Location type | NDMA (ng/L) |
|---|---|---|
| 13 Jan 2009 | Distribution site 1 | 3.6 |
| 13 Jan 2009 | Entry point 2 | 4.3 |
| 13 Jan 2009 | Distribution site 2 | 15.5 |
| 13 Jan 2009 | Entry point 1 | 16.5 |
| 7 Apr 2009 | Distribution site 1 | 4.3 |
| 7 Apr 2009 | Entry point 2 | 5.2 |
| 7 Apr 2009 | Entry point 1 | 23.4 |
| 7 Apr 2009 | Distribution site 2 | 25.0 |
| 7 Jul 2009 | Distribution site 1 | 2.3 |
| 7 Jul 2009 | Entry point 2 | 3.6 |
| 7 Jul 2009 | Entry point 1 | 7.9 |
| 7 Jul 2009 | Distribution site 2 | 18.6 |
| 28 Oct 2009 | Distribution site 2 | not detected |
| 28 Oct 2009 | Entry point 2 | 4.6 |
| 28 Oct 2009 | Distribution site 1 | 5.5 |
| 28 Oct 2009 | Entry point 1 | 36.1 |
Shaded rows are results above 10 ng/L. That is not a legal limit — there is no federal standard for NDMA. It is California's notification level, included here only as a published reference point that readers can measure these numbers against.
These results predate the direct potable reuse project by five years. They were collected under a federal monitoring program, not by the City, and they are published by EPA.
There is no federal maximum contaminant level for NDMA, so these results are not violations of any standard. California, which has no enforceable NDMA standard either, uses a notification level of 10 ng/L; several of these results are above that reference point.
The reason this matters here is simpler than any standard: NDMA was measurably present in Wichita Falls drinking water before wastewater was ever added to the supply.
N-nitrosopyrrolidine (NPYR), another compound in the nitrosamine family, was detected on 28 October 2009 at 2.5 and 3.5 ng/L.
NPYR appears again later in this record. In August 2012, TCEQ recommended that both NDMA and NPYR be monitored in connection with the reuse project, describing them as highly recommended analytes. See the timeline →
What this table shows, and what it does not.
It shows NDMA was present. Fifteen of the sixteen samples reported a detection above the 2 ng/L reporting level, across four quarterly sampling events at four locations. One sample came back below that level. This was not a single anomalous result.
It shows a likely source that is not wastewater. NDMA forms as a disinfection byproduct, and chloramination is a recognized formation pathway. In 2009 there was no potable reuse in Wichita Falls. Whatever produced these detections, it was already part of the system. One caveat belongs here: the records I hold do not yet include a document stating which disinfectant the system used in 2009. That record has been requested.
It does not show a violation. There is no federal maximum contaminant level for NDMA. The City was not required to act on these results, and no finding of non-compliance follows from them.
It does not show what happened later. These are 2009 numbers. They say nothing directly about concentrations during the 2014–2015 direct potable reuse period, or about the current indirect potable reuse system. What they establish is that the question was live before reuse began.
It does not tell us whether anyone was harmed. Nothing on this page establishes a health effect in any person.
Do not take my word for any of this.
This is federal data, published by EPA, free to download. You do not need a records request and you do not need my copy of it.
Go to EPA's UCMR occurrence data page and download the UCMR 2 dataset.
Filter for public water system ID TX2430001 — Wichita Falls.
Filter the contaminant column for NDMA. Results are published in micrograms per liter; multiply by 1,000 to get the nanograms per liter shown above.
Compare to the table on this page. If anything differs, tell me and I will correct it and log the correction.
EPA's published file includes descriptions of the sampling locations, one of which is a street address. The locations are labeled generically on this page for that reason. The underlying file is public and unchanged; anyone who wants the raw site descriptions can download it directly from EPA.
Open EPA's UCMR Data →What happened after 2009.
The timeline follows the record forward: what was recommended, what was monitored, what was removed from monitoring, and what the City operated.