DDW-2025-008900

September 19, 2025
Sent Via Email Only
Katherine Munns
Portage Town Water System
P.O. Box 4
Portage, Utah 84331
[e-mail]
[e-mail]:MPA Result Notification, South Canyon Spring (WS001) and Upper Spring (WS004);Portage Town Water System, System #02012, File #21229
Dear Katherine Munns:
The Division of Drinking Water (Division) suspected the South Canyon and Upper Spring (identified as WS001 and WS004, respectively, in the Division’s database)to be under the direct
influence of surface water (UDI) based on Escherichia coli(E.Coli) positive samples.
AMicroscopic Particulate Analysis (MPA) sample was collected from the combined location for the South Canyon Spring (WS001) and Upper Spring (WS004) on June 9, 2025. The sample scored
0, which indicates a low risk for being UDI. On this basis,the South Canyon Spring (WS001) and Upper Spring (WS004) arenot considered to be UDI at this time.
The Division can re-evaluate this source at any time if there are circumstances that affect its susceptibility to surface water influence. For information about UDI and MPA sampling,
see the attached UDI Definition and Possible Causes.
If you have any questions regarding this letter, please contact Julie Cobleigh, P.E., at [phone] or Brian Pattee, of this office at [phone].
Sincerely,
Michael Newberry, P.E.
Permitting and Engineering Support ManagerJJC/mrn/mdbEnclosure:Laboratory Report of MPA Sample Taken on June 9, 2025cc:Richard Worley, Bear River Health Department, [e-mail]
Munns, Portage Town, [e-mail]
Julie Cobleigh, P.E., Division of Drinking Water, [e-mail]
Division of Drinking Water VSA Team, [e-mail]
David Kruse, Division of Drinking Water, [e-mail]
Cameron Draney, P.E., Division of Drinking Water, [e-mail] 02012 21229 WS001 WS004 MPA Results
UDI Definition and Possible Causes
A groundwater source that is Under the Direct Influence of surface water (UDI) is vulnerable to contamination by pathogens found in surface water. This vulnerability could be because
the sub-surface formation is not sufficiently filtering water as the water percolates through the formation or because the groundwater collection infrastructure is poorly constructed
and allows surface water to directly contaminate the groundwater. The Division of Drinking Water’s protocol determines and classifies a groundwater source as UDI based on one or more
of the following factors:
Physical evidence of source deficiencies that allow, or have the potential to allow, surface water contamination of the source
MPA sampling results indicating surface water influence:
One high-risk MPA sample result
Two consecutive moderate-risk MPA sample results
Inconclusive MPA sample results, such as alternating low-risk and moderate-risk results, along with other water quality data or observations of the source that indicate potential contamination
by surface water
Water quality data indicating contamination by surface water, for example, Escherichia coli positive source sample results not caused by physical deficiencies, detection of Cryptosporidium
or Giardia in the source water, etc.
An MPA test (Item #2) consists of running the source water through a spiral-wound filter for a period of time. Particles collected by the filter are extracted in a laboratory, examined
under a microscope, and identified. Particles that are expected to be found only above ground or in surface water indicate a risk of surface water contamination. Such indicators include
chlorophyll-bearing algae, parts of flying insects, plant debris, Cryptosporidium,Giardia lamblia, etc. Some of these indicators are not pathogens, but their presence in the source water
means the source water is susceptible to contamination by pathogens found in surface water.
An MPA sample is rated as having a low, moderate, or high risk of UDI if the score is 0-9, 10–19, or 20 and above, respectively. When basing the classification of a groundwater source
on MPA results, the Division protocol classifies a source as UDI if any MPA sample is high risk or if any two MPA samples are moderate risk or above.
The path that surface water takes as it flows to a groundwater source can and usually does vary with season and hydrogeological conditions. It is common for the flow path to be directly
influenced by surface water under some conditions, such as during a high surface runoff during spring, but not to be directly influenced under others. So a surface-water-influenced water
source may have MPA sample results of various risk levels, depending on the timing of the sampling. A true groundwater source that is not under the direct influence of surface water
will always have only low-risk MPA results.