North Shore Square mall has been an important economic engine for Slidell since the 1980s, when the city annexed the land to ensure that it would gain the tax revenue generated by cash registers at the center then taking shape next to Interstate 12.

But as rival shopping centers have sprung up in more recent years, including Fremaux Town Center off Interstate 10 on the city’s south side, Slidell officials have been pondering how to prevent the old mall from withering away.

The Slidell City Council took the initial step toward a possible solution last week, creating an economic development district for the mall that will make it possible to levy an additional half-cent of sales tax to be used for improvements and enhancements within its boundaries.

The council will vote Dec. 9 on the additional tax, which would boost the rate within the district from 8.75 percent to 9.25 percent.

The vote would mark the third time the city has used tax increment financing — also known as a TIF — for a retail development, according to Slidell’s chief administrative officer, Tim Mathison. The first was Camellia Square, which, like the mall, was already built when the TIF district was created. The other was for a new development, the Fremaux Town Center, which opened in March and still has future phases to be built.

Mathison called creation of the TIF a first step and noted that many details remain to be worked out in a cooperative endeavor agreement.

Such an agreement could allow the mall’s owners to make improvements designed to attract a new tenant to an anchor store that’s empty, Mathison said.

That’s not an academic question for North Shore Square. Sears, which had been there since the mall opened, shut its doors last month, despite concerted efforts to persuade it to stay.

John Talano, vice president of Morguard Management Co. Inc., which has owned the mall since late 2006, said his company had negotiated aggressively, offering to waive Sears’ rent. But Sears has its own issues as a retailer, he said, alluding to other closings.

Another big question is what will happen to Dillard’s, which owns its two locations in North Shore Square. For that reason, those stores are not included in the economic district, although Talano told the City Council that the TIF could be amended if Dillard’s wants to be added.

City officials and the mall owner do not know what Dillard’s plans to do at North Shore Square, although the retailer has announced its intention to build a store in the second phase of the Fremaux Town Center.

Talano said Morguard’s plans go well beyond renovating an anchor store location. The company is trying to entice new retailers to come to Slidell, he said, and potential tenants are looking for a more comprehensive overhaul of the aging mall.

Most new shopping centers have lifestyle features and are more open, he said, and the mall needs significant improvements to get retailers to come.

Morguard has plans for $25 million to $35 million in work, which would be done in phases, and Talano said the TIF is essential to the plan.

It also would level the playing field with Fremaux Town Center, he said.

Follow Sara Pagones on Twitter, @spagonesadvocat.