CLEARWATER -— Facing strong public opposition, the region's water supply authority again postponed voting on a city of Tampa plan to produce 50 million gallons a day of drinking water by pumping treated wastewater into the Floridan aquifer.

Tampa Bay Water board members voted unanimously to put off making a decision for more than a year, the latest in a string of delays for the $350 million project dubbed "toilet to tap" by critics.

Water board members had already postponed a scheduled October vote until February. In February they postponed it until Monday. On Monday, they agreed there were still too many unanswered questions to make a final decision and postponed a vote once more, this time until June 2020.

"There is considerable public concern and alarm about what effects there might be on the aquifer and our drinking water," Hillsborough County Commissioner Mariella Smith, a water board member, said during the meeting. She said she had asked the Tampa Bay Water staff to ask the city questions about those issues, and most of the answers involved a variation on "we can't tell you until we do a feasibility study."

Smith said she had highlighted in blue ink all the places where that answer had occurred. Then she held up several pages of documents entirely covered in blue highlighter.

The motion to postpone the vote on what Tampa officials call the "Tampa Augmentation Project" came from St. Petersburg council woman Darden Rice, who dangled an incentive for Tampa to agree to another delay: The board would support Tampa's attempt to get $1.6 million from the Legislature to pay for a feasibility study, and if that fell through, then Tampa Bay Water would provide the money itself. Tampa would provide a matching amount.

PRIOR COVERAGE: Is Tampa's toilet-to-tap plan swirling down the drain?

Leaders of local chapters of the Sierra Club and the League of Women Voters strongly urged the board to reject Tampa's proposal. They complained about a lack of transparency, a lack of scientific studies of the potential effects and what they perceived as a rush to gain approval before Bob Buckhorn leaves office as Tampa's mayor.

Tampa's plan calls for ending its legal discharge of its highly-treated wastewater into Tampa Bay, instead pumping the wastewater deep into the aquifer to further purify it, then releasing it into the city's Hillsborough River reservoir near the city's water plant. Tampa officials say that eliminating the minimal nutrients the water currently discharges into the bay from its Howard F. Curren sewage plant would help the environment. They also said the plan would bolster the region's water resources by allowing Tampa to be virtually self-sufficient in water, freeing up water for needier Pinellas and Pasco counties.

But in addition to the environmental questions about the project, critics — including several former Tampa Bay Water officials — have raised concerns that Tampa may be trying to break free from the 20-year-old Tampa Bay Water agency, which was created to end the notorious water wars of the 1990s. Tampa officials have insisted that is not their goal.

PRIOR COVERAGE: Tempers mount over Tampa's plan to turn wastewater into drinking water..

Hillsborough County Commissioner Sandra Murman, who chairs the water board, wanted a guarantee that there would be no further delays beyond June 2020, explaining, "There's got to be a fish or cut bait on this." But board members left the door open for other potential problems in the future.

Contact Craig Pittman at craig@tampabay.com . Follow @craigtimes.