OHA Drinking Water Services
OR41
PWS ID: 00457 ---- LAKE OSWEGO MUNICIPAL WATER

Most Recent Water System Survey
Survey date: Oct 16, 2025
Notification date: Nov 04, 2025 (19 days)
Regulating agency: DWS (REGION 1)
Survey frequency: 3 YR  -  Visit the Water System Surveys page to see the list of surveys due each year.
Significant deficiencies and unmet rule requirements:
Category Significant deficiency or unmet rule requirement Due date Resolved date
Cross Connection Testing records not current (CWS, NTNC, TNC)Dec 23, 2025 Oct 16, 2025
Management & Operations Annual CCR not distributed (CWS)Dec 23, 2025 Sep 02, 2025
Bold text indicates a significant deficiency. All others are unmet rule requirements.


 Hide Site Visit History
Water System Site Visit History
Reason Visit date Frequency Next due Notification date
(Days after survey)		 Responsible
agency		 Comments and
significant deficiencies or unmet rule requirements
Sanitary Survey, Finished (SNSV) 10/16/2025 3 YR  * 11/04/2025 (19) REGION 1 Show details
Sanitary Survey, Finished (SNSV) 06/29/2022 3 YR  * 08/08/2022 (40) REGION 1 Show details
Sanitary Survey, Finished (SNSV) 06/26/2019 3 YR  * 07/25/2019 (29) REGION 1 Show details
Water Treatment Plant Site Visit (TRTP) 06/26/2019 3 YR 06/26/2022 07/25/2019 (29) REGION 1 No details
Sanitary Survey, Finished (SNSV) 09/27/2016 3 YR  * 12/19/2016 (83) REGION 1 Show details
Water Treatment Plant Site Visit (TRTP) 09/27/2016 3 YR 09/27/2019 12/19/2016 (83) REGION 1 No details
Sanitary Survey, Finished (SNSV) 03/28/2013 3 YR  * 06/14/2013 (78) DWP Show details
Sanitary Survey, Finished (SNSV) 03/24/2010 3 YR  * 05/14/2010 (51) DWP Hide details
  Comments:

The significant deficiencies and rule violations noted are as follows:

Treatment Deficiencies
1. Backwash coagulant, RTU-1 polyacrylamide emulsion, is not NSF approved.

Recommendations
* Inspect the 10th Street & Palisades 1 reservoir.
* Determine overflow location at Forest Highlands - 0.5 million gallons.
* Consider updating ERP and/or VA.
* If plant flows exceed 17.6 mgd a new tracer study is required.

Category Significant deficiency or unmet rule requirement Due date Resolved date
Other Treatment Non-NSF approved chemicalsNot tracked
Significant deficiency and unmet rule requirement dates were not tracked prior to 1/1/2014.
Water Treatment Plant Site Visit (TRTP) 03/24/2010 3 YR 03/24/2013 05/12/2010 (49) REGION 2 No details
Sanitary Survey, Finished (SNSV) 07/18/2007 3 YR  * 08/01/2008 (380) DWP Show details