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High Nitrate Levels Found In City Well
city of riverbank

The City of Riverbank’s Well No. 10 had nitrate levels above the allowable limit of 10 milligrams per liter in recent testing. This is the first ever nitrate MCL (maximum contaminant level) exceedance from any of the City’s drinking water wells. Upon notification of the nitrate result from the City’s contract laboratory, the City immediately took Well No. 10 offline and collected confirmation samples from the well.

Officials said that the city will keep Well No. 10 offline until the nitrate issue in this well has been remedied.

“The drinking water that you are receiving now from the City is in compliance with all the drinking water standards including nitrate. As such, the water is safe to drink not only for adults but also the infants,” said the city in a press release regarding the incident.

The water supplied to the residents in Riverbank is comprised solely of groundwater. Groundwater is the water that soaks into the soils from rain or other precipitation and moves downward to fill cracks and other openings in beds of rocks and sand.

“The City has nine wells that all contribute to our water system. No single well supplies water to a specific area of the City; the water that reaches each resident that is part of our water system is a collection of all nine wells,” the press release went on to add.

The City’s Water Department routinely monitors for the presence of drinking water contaminants, and on Tuesday, Nov. 9 the department received notice that one of the nine wells (Well 10) that provides water to the system showed nitrate levels of 18 milligrams per liter. The standard or maximum contaminant level (MCL) for nitrate is 10 milligram per liter. Immediately after the notification, Well 10 was taken offline and remains offline currently. It is important to note that only Well 10 presented the MCL and that the nitrate levels from that one well was diluted by the other eight wells.

“The safety and wellbeing of all our residents is the top priority and we are committed to following the State requirements of notification to all our residents. As of Nov. 10 the system is confirmed to be in compliance and the water being supplied to our residents is safe for all to consume,” said the press release.

The State Water Resources Control Board requires that all residents are notified of these incidents and the City of Riverbank provided this notification via the city website and social media platforms.

Because the Well that exceeded the MCL has been taken offline and the system is testing in the normal standard levels, there is nothing residents need to do.

Well 10 will undergo remediation and continued testing and observation; if and when the well is cleared by the State Water Resources Control Board the well can be reincorporated into the system.

For more information please visit or contact the Public Works Department at 209-869-7128 or email the Public Works Director, Michael Riddell, at