Reports that Lathrop residents became concerned just over a week ago when some noticed that their a tap water smelled different caught a portion of the community by surprise. 

But based on the city’s 2017 Drinking Water Consumer Confidence Report, which details the water quality tests conducted on the city’s water delivery system, those concerns were relatively unfounded.

Lathrop is currently meeting or exceeding all of the drinking water standards set by the federal Environmental Protection Agency, and in some cases is far below the maximum containment level for testable contaminants and inorganic chemicals in both the primary and secondary drinking water standards. 

According to the report, the city’s groundwater wells were well within the standard range for radioactive contaminants — including Gross Alpha and Gross Beta particle activity as well as uranium — and tested far below the maximum threshold for safe water consumption.

Uranium, for example, which leeches into groundwater from the erosion of naturally-occurring deposits, tested at 4.3 picocuries per liter — right in the middle of the average range of not detectable to 8 pCi/L, and far below the maximum containment level, or MCL, of 20. In Gross Beta particle activity, which occurs from the erosion of both natural and man-made elements, Lathrop’s tested water measured only 1.9 with average range that extends up to 5.2, and far below the MCL of 50. 

Other typical areas of concern in drinking water, the concentration of inorganic chemicals that leech from manmade waste as well as naturally-occurring deposits, were well within the acceptable standard. 

Arsenic, which is naturally occurring but is also found in the byproduct of the manufacturing of glass and electronics as well as runoff from orchards, was measured at 7.7 parts per billion which is below the MCL of 10. Lathrop utilizes a state-of-the-art arsenic removal system that binds media to the arsenic particles in water that is known to be high, and then removed to bolster the safety of the water consumed by residents. 

Nitrates, which occur naturally but can also be attributed to runoff from fertilizer placement in agricultural fields as well as leeching from septic tanks and sewage, was detected with an average ppm of 4, far below the MCL of 10. There were no nitrites found in Lathrop’s drinking water. 

Last week, the city reported that the change in color, taste and odor of the water coming from the taps was likely to a surge in the amount of surface water that was pushed through the system as part of a test by the South San Joaquin Irrigation District, and the report details how many of the inorganic compounds found in well water are completely absent from surface water — making it significantly cleaner than what usually comes from the tap. 

Chlorine, which is also used to disinfect well water, is slightly higher in concentration in surface water on average, according to the report, but things like arsenic, barium, fluoride and nitrates aren’t even found in measurable amounts. 

And the odor that was reported by some residents may have an explanation behind it. In the measurement section of secondary standards, which affect taste, smell, and odor, surface water was measured with a unit total of 4 compared to the average groundwater unit total of 1, which the report attributes to chlorine used during the disinfection process. 

The relatively high unit total of four for odor when measuring surface water, where three is set as the typical ceiling, has no health impacts whatsoever since it’s an aesthetic standard. 

Lathrop also has a number of projects that have recently been completed, and several that are ongoing that will bolster the city’s ability to provide clean, safe drinking water to a growing number of residents. 

In the last year, a total of eight water valves which were in need of cleaning, repair or replacement were overhauled — at a cost of $150,000 — and a $350,000 upgrade to the city’s solids handling facility at the wastewater treatment plant is currently under construction and expected to be completed sometime next year. 

The Lathrop City Council approved a draft of the city’s Integrated Water Resources Master Plan earlier this year, and the city has contracted with the De Novo Planning Group to provide environmental consulting services for compliance with the California Environmental Quality Act. 

The council also recently approved purchasing new, unused water metering equipment from a neighboring municipality for $110,207.16 to replace aging and outdated water meters within the city that are no longer giving accurate readings with newer systems and software that tracks water use throughout the city. That particular project is ongoing, and outdated meters will continue to be replaced as they are identified. 

The city’s drinking water is expected to be back to normal by now, but anybody with concerns about ongoing changes to color, taste or odor are urged contact the Lathrop Parks and Recreation Department for follow-up.  

To contact reporter Jason Campbell email jcampbell@mantecabulletin.com or call 209.249.3544.