October 11, 2017
Surface Water Treatment Rule
Turbidity Exceedance Notice
Thief River Falls Public Water System Did Not Meet Treatment Requirements
Our water system recently violated a drinking water standard. Although this was not an emergency, as our customers, you have a right to know what happened, what you should do, and what we did to correct this situation.
We routinely monitor your water for turbidity (cloudiness). This tells us whether we are effectively filtering the water supply. Water samples for the month of September 2017 showed that 22.81 percent of turbidity measurements were over 0.3 Nephelometric Turbidity Units (NTU). The standard is that no more than 5 percent of samples may exceed 0.3 NTU per month. The turbidity levels are relatively low; however, their persistence is a concern. Normal turbidity levels at our plant are 0.08 NTU.
What should I do?
• You do not need to boil your water or take other actions. We do not know of any contamination, and none of our testing has shown disease-causing organisms in the drinking water.
• People with severely compromised immune systems, infants, and some elderly may be at increased risk. These people should seek advice about drinking water from their health care providers. General guidelines on ways to lessen the risk of infection by microbes are available from USEPA Safe Drinking Water Hotline at 1 (800) 426-4791.
What does this mean?
Turbidity has no health effects. However, turbidity can interfere with disinfection and provide a medium for microbial growth. Turbidity may indicate the presence of disease causing organisms. These organisms include bacteria, viruses, and parasites which can cause symptoms such as nausea, cramps, diarrhea, and associated headaches. These symptoms are not caused only by organisms in drinking water. If you experience any of these symptoms and they persist, you may want to seek medical advice.
What happened? What was done?
A problem occurred with the treatment system at the water plant. On September 2nd 2017, the Ferric Sulfate concentration in teh Wash Water recovery basin was elevated so when that water was blended back into the pre-sedimentation basin, the concentration was too great at the flow rate the plant was set at. The blow-offs were operates more frequently unti lthe turbidity samples were brought back into compliance on September 13th.
For more information, please contact Wayne Johnson by phone, at 218-681-3809 or by mail, P.O. Box 528 Thief River Falls MN 56701.
This notice is being sent to you by Thief River Falls Public Water System
State Water System ID# 1570003
Date Distributed: 10/11/2017


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