OHA Drinking Water Services
OHA Drinking Water Services
Contact Report Details

PWS ID: OR41 05549
Who Was Contacted: Lisa Cornell
Contact Phone: 541-260-2627 (Email address hidden)
Contact Date: 03/31/2021
Contacted By: DOWNS, KENT (DWP)
Contact Method/Location: Email
Assistance Type: OTHER REGULATORY - Operator Info request - E. Coli Contaminated Spring, chlorination and Safe drinking water
Reasons: GWR
Details: 03.31.21 - I received a letter dated 3/14/2021 from the operator asking “Why have the results for the households run on 2/8/2021 at the same time as the source sample been totally ignored?

The samples are not being ignored. However, the absence of E. Coli bacteria in the household samples can’t be considered as a conclusive proof that your water is safe to drink.

Reasons provided to the operator:
- E. Coli bacteria present in a groundwater source is an indicator of possible parasites and viruses in the water. It also tells us that it is possible your spring is contaminated
with surface water.

- As shown by the household test results collected on 02.08.2021, chlorine is able to kill E. Coli bacteria present in the source. However, chlorine alone is not sufficient to remove-inactivate parasites, an approved filter is needed as well as the appropriate disinfection contact time to inactivate parasites (Giardia).

At this point the source is not considered surface water so there is no requirement to treat for Giardia. However since the spring source has been confirmed to have E.coli present, the operator has to be able to achieve 4.0 log inactivation of viruses in order to lift the boil water notice.

To effectively destroy/inactivate viruses to a level where the system is protecting the public health, 4-log treatment or 99.99% removal and/or inactivation of viruses is needed. In other words, the operator has to determine how much chlorine contact time is needed before the first user and then calculate a minimum concentration of chlorine that must be maintained at all times at the first user to ensure 4.0 log inactivation of viruses. A link to determine the 4-Log inactivation of viruses was provided and the operator was instructed to contact Rick Hallmark for assistance.
Associated Alerts: COLI20818 - 02/10/2021 - COLIFORM (TCR) , E. COLI  See also: 02/10/2021, 03/15/2021

COLI20823 - 02/10/2021 - COLIFORM (TCR) , E. COLI  See also: 02/10/2021, 02/10/2021, 03/15/2021, 02/10/2021

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