Even in the face of strident protests by many residents, St. Tammany Parish officials have for more than a month insisted that the parish is largely powerless to stop a proposed “fracking” oil well in an undeveloped 960-acre tract just north of Interstate 12.

Despite their earlier arguments that state law reserves decisions on drilling to state agencies, though, it now appears that Tammany officials are hoping to use parish zoning law to block the project.

Parish President Pat Brister and 13 of the 14 Parish Council members have signed a letter to James Welsh, the state’s commissioner of conservation, arguing the proposed well would violate parish zoning rules and urging Welsh to deny a drilling permit for the project.

The lone councilman to not sign the letter, Steve Stefancik, was out of town and could not be reached, according to the letter.

Dated May 23, the letter points out that the tract under consideration is zoned A-3, or suburban. “Conducting oil and gas drilling is not among the uses that are permitted on property classified as an A-3 Suburban District,” the letter says.

The parish enacted a comprehensive zoning ordinance in 2010 and every property owner in the area was notified and had an opportunity to object, the letter says, implying that the owners of the proposed drilling site were silent when the land was zoned suburban.

“We respectfully submit to you, based on the above, that the issuance of a permit to conduct oil and gas drilling operations on property zoned for A-3 Suburban District would not be a reasonable and appropriate exercise of your authority for the issuance of oil and gas drilling permits,” the letter concludes.

Despite the letter’s assertion of the parish’s rights, though, it’s unclear whether it will have any impact on what Welsh decides.

Helis Oil & Gas, the company proposing to drill the well, has yet to formally apply for a drilling permit. Before it can do so, Welsh must approve the boundaries of the “unit” or tract of land from which the oil and gas would be extracted.

Welsh is slated to hear Helis’ application for a unit order June 17, after the company agreed to postpone the hearing 30 days so that parish officials could research the issue further. If, as expected, Welsh approves the unit, Helis could then apply for a drilling permit.

Company officials have said they would like to start construction on the drill pad — the 10-acre site on which the actual well would be constructed — this summer.

Once a drilling permit is issued, Helis could drill the well and employ a method known as hydraulic fracturing, or fracking, to extract oil from the Tuscaloosa Marine Shale formation 13,000 feet underground. The method involves injecting water, sand and chemicals into the ground to create fissures in rock through which oil and natural gas can be pumped to the surface and collected. The method has been controversial in other parts of the country, and bans have been attempted in some places, with varying degrees of success.

Much of the opposition in St. Tammany has focused on the project’s potential impact on the parish’s sole water supply, the Southern Hills Aquifer. The well would be drilled through the aquifer, and some activists have questioned whether it could be made safe enough to prevent drilling fluids or oil from leaking into the water supply.

Helis and oil industry representatives have repeatedly insisted that the method is safe and that they would put three layers of casing and cement around the section of the well shaft that goes through the aquifer.

Those assurances have done little to assuage critics’ concerns, however, and active campaigns have been launched to block issuance of the drilling permit as well as a wetlands permit needed from the U.S. Army Corps of Engineers.

In addition, the Parish Council earlier this month approved the hiring of special counsel to help protect the parish’s interests, and Brister has said she is working with council members on ordinances to regulate pre-drilling water testing, noise, hours of operation and possible impacts on roads, among other things.

In addition, opponents are preparing signs to go in the windows of businesses, and the owners of all of the parish’s more than 300 water systems — many for individual trailer parks, campsites or the like — have been urged to join the protest movement.

Parish Councilman Jake Groby, who has steadfastly opposed the proposed well, said he hopes the pressure will bear fruit.

“I think if we get enough letters and enough attention, he (Welsh) and his office may sit down and legitimately contemplate whether they want to do this,” he said. “We are doing our level best to get everybody on board with this.”

Follow Faimon A. Roberts III on Twitter, @faimon.