IMPORTANT WATER UPDATE FROM THE CITY OF YUMA

Yuma, Arizona - The City of Yuma wants to keep you informed about a recent water quality notice for our water distribution system.

On Saturday, June 7, a sample taken directly from the plant showed a higher-than-allowed level of chlorine dioxide, a product used in small amounts to control taste and odor in the drinking water. The reading was slightly above the regulatory limit.

Here's what you should know:

• In response to the result, the Agua Viva Water Plant immediately stopped using chlorine dioxide.
• Follow-up testing confirmed that the water remains safe to drink. Additional samples from nearby areas, all came back non-detect - showing no concerning levels of chlorine dioxide in your drinking water.
• The issue arose because staff mistakenly reported the exceedance as a different chemical (chlorite), and did not collect all the follow-up samples required by regulation for chlorine dioxide. This was an administrative monitoring error.

The Agua Viva Water Plant already updated all procedures to make sure this doesn't happen again.

Bottom Line:

• Your water is safe.
• No action is needed - you can continue to use and drink your water as usual.
• A formal public notice is available below.

If you have questions, please contact Christopher Grant at 928-373-4628.

The City of Yuma appreciates your understanding and remains committed to transparency and the safety of your drinking water.

IMPORTANT NOTICE REGARDING YOUR DRINKING WATER

A HIGH LEVEL OF CHLORINE DIOXIDE WAS DETECTED

What Happened and How Did We Respond?

On June 7^th, a sample collected at the Agua Viva Water Plant had chlorine dioxide levels of 1.15 milligrams per liter. This is above the standard, or maximum residual disinfectant level (MRDL) of 0.8 milligrams per liter.

In response to this result, we immediately stopped the use of chlorine dioxide and checked a sample location about 2000 feet from the Plant. The result for chlorine dioxide was non-detect. Additionally, a sample collected on June 8^th was non-detect for both chlorite and chlorine dioxide. The city is confident that the City's drinking water is safe, and no action is necessary from residents.

In accordance with regulatory requirements, another chlorine dioxide sample was taken at our treatment plant on the morning of June 8^th. This sample was non-detect for chlorine dioxide. We also sampled (as required) at three locations downstream of our treatment plant. Unfortunately, Operational Staff reported the exceedance as being for chlorite and not for chlorine dioxide. Because of this, samples were collected for chlorite and not for chlorine dioxide the following day in the distribution system. This failure to monitor in the distribution system for chlorine dioxide is the reason for this notification.

This deficiency is being corrected by requiring distribution system sampling for both chlorine dioxide and chlorite on the day following any exceedance.

What are the Effects of Chlorine Dioxide?

Chlorine dioxide is used in small amounts every day to kill bacteria and other organisms that may be in your drinking water. Chlorine dioxide breaks down very quickly in the water system, dissipates within 48 hours, and can be removed through home reverse osmosis systems. It is used for disinfection, but too much of it over a short period of time may harm the development of children, infants, and fetuses. Some infants and young children who drink water containing chlorine dioxide in excess of the MRDL could experience nervous system effects. Similar effects may occur in fetuses of pregnant mothers who drink water containing chlorine dioxide in excess of the MRDL. Some people may experience anemia.

On the morning of June 9, 2025 our water laboratory crew collected and tested additional samples at various locations in the distribution system, showing no chlorine dioxide in your water. Additionally, an inline meter, which continuously monitors chlorine dioxide levels entering the distribution system, showed no instances of chlorine dioxide above the detection level of 0.041 mg/L. You do not need to avoid the tap water or use an alternate source, such as bottled water.

For more information, please contact Christopher Grant at 928-373-4628 or 270 W 13^th Street, Yuma AZ 85364.

Please share this information with all the other people who drink this water, especially those who may not have received this notice directly (for example, people in apartments, nursing homes, schools, and businesses). You can do this by posting this notice in a public place or distributing copies by hand or mail.*

This notice is being provided to you by the City of Yuma. State Water System ID#: AZ0414024 on 6/9/2025

We appreciate your understanding and remain committed to transparency and the safety of your drinking water.