Government sampling in Fresno County’s S100CNRLVL aquifer shows sulfide was detected in about half of tested wells, with values ranging from none detected up to 0.43 mg/L, based on 34 samples collected across 32 wells between 2010 and 2021.
Sample Size and What It Means for Your Water
The data behind these figures come from 32 wells sampled over an 11-year span, with well depths varying from 78 to 1020 feet. While this offers a regional snapshot of sulfide presence, it does not define the condition of any individual household water supply. A limited number of samples means variability can exist beyond this range, so local conditions and specific wells may differ.
Measured Range Compared to Federal Standards
None of the sulfide measurements from these samples exceeded federal thresholds. This means the sulfide concentrations found in the tested wells do not indicate a breach of safety standards. However, sulfide can cause an unpleasant sulfur or rotten-egg odor in water, affecting water’s aesthetic quality even when it is safe. These aesthetic impacts can be a concern for households considering treatment.
Additional Considerations for Non-Residential Users
Commercial or industrial users might face stricter or different water quality requirements that could require more detailed analysis. Households generally focus on taste and odor issues, while larger-scale operations may need to consider process water standards or regulatory compliance beyond what the government sampling covers.
Understanding Detection, Median, and Range in the Sampling Data
"Detected" means the presence of sulfide was measured at some level; "median" represents the middle value of all measurements, showing the typical concentration; and "range" reflects the full spread from the lowest to highest value observed. For Fresno County’s aquifer, the median sulfide is 0.02 mg/L, indicating that half the samples measured less and half measured more, with some wells showing no sulfide and others up to 0.43 mg/L.
Comparing Fresno County with Neighboring Areas
When looking at sulfide data from nearby counties, remember that geology, water table depth, and land use vary, which can affect sulfide presence. It’s important not to assume conditions in Fresno County are identical elsewhere. Each region’s sampling data should be reviewed independently to avoid overgeneralizing.
Laboratory Testing and What Results Mean for Your Home
To know your household water’s specific sulfide concentration, a certified laboratory test is needed. Such testing reports the actual concentration in your water rather than regional estimates. This helps in making an accurate assessment of whether sulfur smell treatment is necessary and what treatment technology fits.
Deciding on the right treatment depends on recognizing regional water characteristics and confirming your own water’s quality. The Fleck Rotten-Egg Sulfur Smell Filter ships ready to configure and provides a proven solution specifically targeting sulfur odor issues identified in water like that from Fresno County’s S100CNRLVL aquifer.
Where this information comes from
Source: USGS groundwater sampling. Sampled 2021-03-01. These figures describe groundwater sampled in this area. They are not a test of any individual private well - only a test of that well can establish its own water.
On record: U.S. Geological Survey sampling of Sulfide in the S100CNRLVL aquifer (Fresno County): 34 results from 32 wells, median 0.02 mg/L, range 0.0-0.43 mg/L; none above any federal threshold