TULALIP — Those who have stopped by the Seattle Premium Outlets on the Tulalip Reservation since the fall of last year might have noticed a new development to the west of the outlet center.

Last summer, the the Simon Property Group announced their plans to expand the Seattle Premium Outlets’ retail space, since the outlet center’s existing 120 stores produce sales in excess of $700 per square foot, making them one of the group’s most productive centers.

As part of that expansion, S.D. Deacon — the same contractor that originally built the Seattle Premium Outlets in 2005 — began construction on a two-level parking deck on the west side of the outlet center in October of 2011.

According to Michele Osgood, assistant general manager of the Seattle Premium Outlets, this new parking area is slated to be open in the summer of 2012, in time to provide additional parking in advance of the planned expansion of the outlet center that’s set to follow.

“The planned expansion will add 100,000 additional square feet of retail space to the outlet center in 2013, bringing the total square footage of the center to 500,000,” Osgood said.

Osgood declined to specify how many parking spaces would be added with this move, just as Michele Rothstein, a spokesperson for the Premium Outlets division of Simon, had previously declined to speculate on how many new stores would be added during the expansion, or which ones they would be.

The Seattle Premium Outlets were built in 2005 and include Adidas, Ann Taylor, Banana Republic, Calvin Klein, Coach, Cole Haan, DKNY, J.Crew, Kenneth Cole, Lacoste, Nike, Polo Ralph Lauren and Tommy Hilfiger.

Rothstein attributed the stores’ sales success to shoppers coming from the local area, throughout the Puget Sound region and even from Canada. She predicted that the Cabela’s store currently under construction at Quil Ceda Village, just south of the Seattle Premium Outlets and the Tulalip Resort Hotel and Casino, would also draw customers to those stores.

“The Tribes are very excited about this,” Tulalip Tribal Chair Mel Sheldon Jr. said. “It furthers our goal of making this a destination resort and gives shoppers even more choices.”

Sheldon credited his predecessors and peers on the Tribal Board with laying the groundwork for the Tribes’ ongoing economic expansion, which he hopes will benefit the Tribes’ neighbors and Snohomish County as a whole.