OHA Drinking Water Services
Contact Report Details |
|||
| PWS ID: | OR41 00665 | ||
| PWS Name: | TUALATIN VALLEY WATER DISTRICT | ||
| Who Was Contacted: | Joel Cary | ||
| Contact Phone: | (Email address hidden) | ||
| Contact Date: | 09/23/2025 | ||
| Contacted By: | ALFAFARA, NICOLE (DWP) | ||
| Contact Method/Location: | |||
| Assistance Type: | MONITORING | ||
| Reasons: | Other |
||
| Details: | The system submitted a request to invalidate previously reported alkalinity data and provided a revised CCTX report containing new alkalinity results. While initial correspondence referred to this as an “amended report,” the request is more accurately categorized as an invalidation of prior data and submission of a new report. A split laboratory analysis of alkalinity at five sampling sites (some meeting and others not meeting the minimum alkalinity requirement) identified discrepancies of 5% to 17% from the originally reported values. Based on these inconsistencies, the system determined that the original data were unreliable and untrustworthy, and therefore requested invalidation. The system submitted new alkalinity data within the applicable monitoring period, maintaining the original sampling locations where possible. Two locations were replaced with hydraulically and geographically comparable sites due to missing corresponding pH values. DWS staff reviewed the new submittal and determined the revised data may be accepted for compliance. The system will continue on annual L&C monitoring, maintaining an alkalinity minimum of 7.4 in the distribution system (sampled and reported annually with L&C results) and 7.7 at EP-C (monitored monthly and reported only when the source is in use). |
||