Groundwater in Glenn County contains manganese, nitrate, iron, arsenic, chloride, and sulfate at levels that exceed EPA health standards. Several of these contaminants are present at concerning concentrations that warrant attention from well owners.
These contaminants come from two main sources. Nitrate and chloride enter groundwater from agricultural activities and fertilizer use across the valley. Manganese, iron, arsenic, and sulfate occur naturally in the local rock and sediment, dissolving into water as it moves underground through the aquifer.
Groundwater in Glenn County is very hard, driven primarily by calcium and magnesium from the surrounding rock. The local geology naturally concentrates these minerals as water passes through the aquifer, and this pattern appears across most wells in the county. Sodium levels are moderate, and sulfate concentrations remain low despite the natural mineral character of the water.
Wells in Glenn County commonly have arsenic, chloride, nitrate, iron, and manganese at levels that exceed EPA health standards. Arsenic and nitrate can cause health problems with long-term exposure, including increased cancer risk and issues with infant development. Iron and manganese at high levels can affect organ function over time. These contaminants come from natural sources and human activities in the groundwater.
The very hard water in county wells leaves white crusty buildup on faucets, shower heads, and fixtures. It causes soap to work poorly and can make laundry feel stiff. The hardness can shorten the lifespan of water heaters and dishwashers over time. You may also notice a metallic or unpleasant taste in the water.
We recommend testing your well water with a comprehensive panel to see what is actually in your water, since every well is different and yours could have higher or lower levels than what is common in the county. Testing is the only way to know what needs treatment. A comprehensive metals and minerals panel typically costs two hundred to four hundred dollars. Water softeners and iron filters are common treatment options for the mineral concerns in this area.
Not sure if your well is affected? Get certified results in 5–7 days.
Test Your Well Water with Tap Score →| Contaminant | Samples ⓘ | % Above MCL ⓘ | Distribution ⓘ | Confidence ⓘ | Risk ⓘ |
|---|---|---|---|---|---|
| Manganese | 130 | 12% | High | Moderate | |
| Nitrate | 421 | 4% | High |
Moderate
Elevated concentration, not % above limit
|
|
| Iron | 135 | 3% | High | Low | |
| Arsenic | 125 | 2% | High | Low | |
| Sulfate | 391 | 0% | High | Low | |
| Chloride | 482 | 0% | High | Low | |
| Lead | 81 | 0% | Moderate | Low | |
| PFNA ⓘ municipal | 19 | 0% | Moderate | Safe | |
| Uranium | 66 | 0% | Moderate | Low | |
| Radon | 1 | 0% | Low | Low ⓘ | |
| PFOS ⓘ municipal | 19 | 0% | Moderate | Safe | |
| Boron | 2 | 0% | Low | Low ⓘ | |
| Chromium (total) | 2 | 0% | Low | Safe ⓘ | |
| 1,2,3-Trichloropropane | 3 | 0% | Low | Safe ⓘ | |
| HFPO-DA (GenX) ⓘ municipal | 19 | 0% | Moderate | Safe | |
| Fluoride | 223 | 0% | High | Low | |
| Nitrite | 73 | 0% | Moderate | Low | |
| Perchlorate | 3 | 0% | Low | Safe ⓘ | |
| PFHxS ⓘ municipal | 19 | 0% | Moderate | Safe | |
| PFOA ⓘ municipal | 19 | 0% | Moderate | Safe | |
| Tds | 2 | — | Low | Low ⓘ | |
| Total Coliform | 1* | 0% | Low | Safe ⓘ | |
| Hardness | 491 | — | High | Low | |
| PFBS ⓘ municipal | 19 | — | Moderate | Safe | |
| pH | 648 | — | High | Low | |
| E. coli | 1* | 0% | Low | Safe ⓘ | |
| Sodium | 424 | — | High | Low |
MCL = Maximum Contaminant Level (EPA limit for public water; used as benchmark for private wells). Distribution shows % of sampled wells in each concentration band. Methodology.
* Microbial contaminants (E. coli, coliform) reflect only samples from the last 10 years.
Data shows potential risk — a certified test confirms whether your water is affected.
Order a Tap Score Test →Population-level CDC data. Not individual risk prediction.
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