Well Water in Mono County: What to Test and Why

Groundwater in Mono County contains arsenic, manganese, uranium, chloride, fluoride, and sulfate at levels that exceed EPA health standards. These contaminants are present at concentrations the EPA considers concerning enough to regulate.

The Basin and Range landscape here creates conditions where these metals and salts accumulate in groundwater. Arsenic, uranium, and manganese dissolve naturally from the rocks and minerals in the basin-fill aquifers. Chloride, fluoride, and sulfate also come from the surrounding rock layers. The dry climate and internal drainage typical of this region mean water sits underground longer, allowing more minerals to dissolve.

Groundwater in this county is moderately hard, driven mainly by sodium and moderate hardness minerals. The basin-fill rocks release these dissolved solids slowly into the water as it moves through them. Wells across the county commonly show these moderate mineral levels, though individual wells vary depending on their depth and location.

Wells in Mono County have been found to contain arsenic, uranium, fluoride, and manganese at levels above EPA health standards. Arsenic and uranium are radioactive elements that can increase cancer risk with long-term exposure. Fluoride at high levels can cause dental problems and bone issues. Manganese can affect the nervous system and brain development, especially in children.

County well water tends to be moderately hard, which means you might see white scale buildup on faucets and fixtures or inside pipes. Hard water can reduce how well soap works for cleaning and leave spots on dishes and glassware. Over time, mineral buildup can shorten the lifespan of water heaters and dishwashers. You may also notice a slight taste or odor difference in your water compared to treated public water.

We recommend testing your well water with a comprehensive metals and minerals panel, since several analytes exceed standards in this county. Every well is different, and your water could have higher or lower levels than what is common here. Testing is the only way to know exactly what is in your well so you can decide on proper treatment. A comprehensive panel typically costs between $200 and $400 and can identify all the contaminants present, and treatment options like reverse osmosis or activated carbon filters can remove many of these substances.