What type of notification is required from the operator when changes to a public water system occur?

When there are changes to a public water system, it is crucial for the operator to provide notification particularly in instances of any change in water source, water quality, or health hazards. This is essential because public health may be at risk if the quality of the water supply is compromised or if there are potential health hazards associated with the water being supplied to consumers. Timely and accurate communication ensures that all stakeholders, including regulatory agencies and the public, are informed about the state of the water being delivered, allowing for appropriate measures to be taken to protect public health.

The other options do not represent critical changes that would necessitate immediate notification to regulators and the public. Maintenance schedule updates, while important for operational purposes, generally do not have the same direct impact on public health. Annual chemical analysis reports may be required, but they represent historical data rather than immediate changes in the water system. Public awareness campaigns, while valuable, do not typically involve necessary notifications regarding the safety or quality of the water itself.