City commissioners said they believe the changes are firmly rooted in better science and modeling than what was available almost three decades ago, when the original plan was adopted.
But opponents said the commission’s decision is short-sighted and increases the risk of contamination facing the ground water system.
A large crowd packed into Dayton commission chambers in anticipation of the vote. The meeting lasted for more than three and a half hours. There were public hearings on the proposed revisions to the zoning map boundaries and the zoning code.
The proposal would reduce the size of the protected area by 12 percent, removing about 544 acres, but increases fines and the number of prohibited chemicals in the protected area to 26 from eight. Also, the city has 300 early-warning monitoring wells and 200 production wells; 150 monitoring wells would be added.
The plan also will create a variance process that allows businesses to add chemicals based on demonstrated needs.
Tammi Clements, the director of the city’s water department, said the sensitive protected area will shrink because the modeling, monitoring and geological information supports the change.
But she said the city is expanding the area that city staff monitors for contamination. She said staff will identify and work with businesses with chemical inventories to reduce contamination risks and avoid undesirable land uses.
“This will (provide) a higher level of protection than we have today,” she said.