What does the Murray City water record tell us about chromium-6 in Salt Lake County?
The Murray City Water System serves over 38,000 people in Salt Lake County using groundwater. Federal monitoring from 2013 to 2015 found chromium-6 (also called hexavalent chromium or chromium(VI)) was detected in most samples, with levels ranging up to 1.51 micrograms per liter (µg/L), equivalent to parts per billion (ppb). While these detections show chromium-6 is present in the water supply, no federal maximum contaminant level (MCL) currently applies to chromium-6, and the total chromium levels recorded stayed well below the EPA’s total chromium MCL of 100 µg/L. This means the presence of chromium-6 here is not regulated as a violation or considered unsafe based on federal standards. It’s important to note that these results describe the water system’s supply and do not reveal conditions in any individual household’s water.
Why did California establish its own 10 µg/L limit for chromium-6, and what does that imply for Salt Lake County?
California set a public health goal of 0.02 µg/L and a regulatory limit of 10 µg/L for chromium-6, reflecting concerns about its potential health effects based on state-level assessments. This limit is specific to California and does not apply federally or in Utah. For households in Salt Lake County, this means there is no similar state-mandated limit for chromium-6 in their water supply. The California limit provides a reference point but does not define safety or regulatory status for water in this region.
What are common sources of hexavalent chromium, and which supply types are most affected?
Chromium-6 in groundwater can originate from natural geogenic sources, especially in arid, alkaline aquifers like those found in parts of Utah. It also can come from industrial activities such as metal plating but Murray City’s groundwater is the source here. This suggests that the chromium-6 detected is largely from natural geological conditions rather than industrial contamination. Understanding this helps homeowners consider the nature of chromium-6 in their water and its likely persistence.
What was the purpose of the UCMR3 survey that measured chromium-6, and what are the limits of its findings for a household?
The EPA’s Unregulated Contaminant Monitoring Rule (UCMR3) survey was designed to gather nationwide data on contaminants like chromium-6 to inform potential future regulations. It is a broad snapshot taken at select system points, not a compliance test or household-specific analysis. For any particular home, the actual chromium-6 concentration could be different due to variations in source water, plumbing, and treatment. Homeowners should perform individual water testing to know their own water quality.
How does chromium-6 typically enter household water and impact specific fixtures or appliances first?
Chromium-6 comes from the groundwater source and is delivered into the distribution system. Its presence in pipes can be influenced by changes in water chemistry that may alter its oxidation state. Appliances and faucets that use a lot of water, like drinking fountains or kitchen taps, may reflect chromium-6 levels more directly. Hot water systems may show different chemistry affecting chromium species. Knowing this can guide which water points homeowners test or consider protecting first.
What does the range of chromium-6 measurements mean compared to federal standards, and what should not be assumed?
The highest chromium-6 concentration measured in the Murray City Water System was 1.51 µg/L, which is well below the EPA’s total chromium MCL of 100 µg/L and is not a violation or safety finding. Chromium-6 detections indicate measurable presence but do not establish health risk without further context. Readers should not conclude that their home’s water matches these results, nor assume that chromium-6 here indicates unsafe water. Testing is necessary for individual assessment.
What should residents avoid concluding from community-level chromium-6 data?
Households should not assume that the area-wide monitoring figures represent their own water’s exact chromium-6 concentration. A detection in the water system record is not an exceedance of a legal limit or a health-based violation. This data does not guarantee any specific treatment need or water safety status for an individual home. To evaluate chromium-6 at a household level, water testing from the tap is essential.
For households seeking to address chromium-6, equipment using a Fleck System designed for chromium-6 filtration ships ready to configure and can provide a documented treatment approach tailored to reducing chromium(VI) where testing shows it is needed.
Where this information comes from
Source: EPA SDWIS public water system record. Sampled 2015-03-27. These figures describe the public water system's record, not the plumbing inside any individual building.
On record: EPA UCMR3 monitoring (2013-2015) for Murray City Water System (UTAH18024), UT: 74 results across 2 listed contaminants, 64 detections above the reporting level; no federal MCL for hexavalent chromium; total chromium MCL 100 ug/L
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