CLEARWATER — For 20 years, the regional water supply agency known as Tampa Bay Water has provided the state with an example of how local governments can cooperate to provide a vital resource to a large metro region.

Now a pair of bills in the Legislature may dismantle the whole thing — and they're being backed by the City of Tampa.

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The fight is over millions of gallons of highly-treated reclaimed water — essentially, wastewater stripped of ammonia, chlorine and other chemicals so that it's nearly pure enough to drink — which Tampa wants to use in its drinking water supply.

The city could also sell this new source of drinking water. But Tampa Mayor Bob Buckhorn denied Monday that profit was motivating the city to pursue the project against the wishes of Tampa Bay Water.

Buckhorn said he personally requested the two bills because the utility has spent the last year "stonewalling" the city's request to use that water source in this way. "We did this because we had to," he said.

The bills are sponsored by two Tampa legislators from each party — SB 1710, sponsored by Republican state Sen. Dana Young, and HB 1303, sponsored by Democratic state Rep. Janet Cruz. They call for giving each city or county that is a part of Tampa Bay Water "the absolute right" to use its highly-treated reclaimed water as a drinking supply that it can either use or sell to the other members.

Although the bills say they're not intended to mess up the interlocal agreement that formed Tampa Bay Water two decades ago, that's exactly what it could do, said Pete Dunbar, a former legislator who serves as the agency's longtime Tallahassee lobbyist.

Buckhorn denied that, labeling Dunbar's comments "scare tactics."

In a year when local governments across the state are fending off efforts by the Legislature to dictate their actions on a wide variety of issues, the bills targeting Tampa Bay Water ticked off some members of its governing board.

"It's important that this region speak loudly to say to our Legislature: 'Enough!' " Pinellas County Commissioner Dave Eggers said.

The board voted 6-3 at an emergency meeting Monday to oppose the two bills. The three votes against that motion were cast by the two Hillsborough County commissioners on the board, Sandra Murman and Pat Kemp, and Tampa City Council member Charlie Miranda.

After the meeting, Miranda said that despite that vote, his city will continue pushing the Legislature to pass the two bills, both of which have yet to move through their respective committees. Miranda also said he sees nothing wrong with tinkering with the interlocal agreement: "Even the Constitution was amended."

Tampa Bay Water was the first wholesale utility of its kind in Florida, uniting the bay area's often fractious governments. It was born of the contentious water wars of the 1980s, when bay area governments spent millions on lawyers' fees battling each other over the water in the aquifer.

Finally the Southwest Florida Water Management District — commonly known as Swiftmud — stepped in and forced a truce which led to the formation of the regional utility, run by a board made up of representatives of Pinellas, Hillsborough and Pasco counties and their three largest cities, St. Petersburg, Tampa and New Port Richey.

With financial help from Swiftmud, Tampa Bay Water built a desalination plant, the state's largest reservoir and a large surface-water treatment plant. Those alternative supply sources enabled the agency to reduce what's being pumped out of the ground and restore dwindling lakes and drying wetlands.

The pursuit of alternative water sources has now turned to the use of reclaimed water, sometimes derisively dubbed "toilet-to-tap" water. The water supply at stake here is a step above reclaimed water: The chemicals used to treat the water have been stripped away in a process called Advanced Wastewater Treatment, making it legal to dump into the bay. That's where it goes now, but Tampa wants to do more than just throw it away.

Tampa Bay Water has been working on a plan to use highly-treated reclaimed water too, but it hasn't moved nearly as fast as Tampa has.

Instead of dumping its reclaimed water into Tampa Bay, the city wants to build a pipeline and pump the water 9 miles to the north. Up to 50 million gallons a day would be pumped 900 feet underground into the aquifer.

Later the city would pump it back up from a depth of 300 feet, which city officials say would provide natural treatment for the water. Roughly half of the water recovered from the aquifer would be sent to the city's David L. Tippin Water Treatment Facility. The other half would go into the Hillsborough River reservoir upstream from the city dam at Rowlett Park.

There, officials say, it would keep the reservoir full even during the winter dry season. It also would let the city provide an estimated 20 million gallons of water a day to the Tampa Bay Water treatment plant north of E Adamo Drive and near U.S. 301.

Tampa estimates its system would cost $250 million to $300 million. City officials think they could start construction on the system within five years.

But last fall, Tampa Bay Water officials questioned whether Tampa has the ability within the interlocal agreement that created the agency to create a source of potable water for itself or other member governments independent of the utility.

Given the threat posed by the two bills, though, Tampa Bay Water general manager Matt Jordan said the agency could deliver its expected April report on the re-use of highly-treated reclaimed water by mid-February.

Times staff writer Richard Danielson contributed to this report. Contact Craig Pittman at craig@tampabay.com. Follow @craigtimes.