Water Well 13 is not contaminated with cyanide. The latest water quality reports submitted and approved by the State Water Resources Board can be found here and show no measurable cyanide levels: https://paramountenvironment.org/annual-water-quality-reports/
The City performs regular testing of the water system as required by law. Should any negative results come about, the City will (in compliance with the law) inform the community about any negative health effects.
Water Well 13 is not shut down and is still operational, however, it is slated to be taken offline in the near future as part of a long-term strategy for the City’s water supply. The well is being replaced with a newer well that is deeper into the ground and uses newer equipment that is more energy efficient. Water Well 13 has outlived its expected life of 30-40 years and is due for replacement (it has been operating since 1978).
There was a history of manganese being present in the water at Water Well 13, and in 2003 the City implemented a filtration system to address these levels (see City Council presentation from 2003 here). Manganese is not a risk to public health, but it can damage pipes and discolor water. Mitigating the manganese requires the presence of an onsite backwash tank that is prominently located on the Water Well 13 property. There is no diesel fuel on the property or immediately adjacent to Water Well 13.
Water Well 13 testing during 2003 detected arsenic in the water supply, and this concern has been addressed on the website here: https://paramountenvironment.org/ufaqs/claim-paramounts-well-13-is-an-active-well-used-for-drinking-water-and-contains-high-levels-of-arsenic-above-the-environmental-protection-agencys-epa-maximum-contaminant-level-mc/.