Most of the urban cenotes in Cozumel are unfortunately not ones I would want to dive in but it is good they are doing research to hopefully raise awareness.
For example, Cenote Chu-Ha (San Francisco) behind the Ecology office on Av65 has very high levels of fecal coliform.
Exceeds the maximum permissible limits of fecal coliforms and Escherichia
coli, according to NOM-001-SEMARNAT-2021 for karst environments.
High number of fecal viral indicators (greater than 100 genome copies), increases the probability of presence of some enteric transmitted virus and the risk of human exposure, with affectation to your health.
Presence of the metals barium and zinc in sediments that may become available to the environment
Very interesting report here.