LAKE STEVENS — The possibility of a Costco coming to Lake Stevens is moving closer to reality.

The retailer has applied for a design and site plan review through the city. It also has received a planned action certificate, and can move forward with environmental reviews.

The store would go on the southwest corner of Highway 9 and 20th Street SE, according to the application. There’s no timeline yet for construction to start.

“We are still fairly early on in the project,” said Russ Wright, the city’s community development director.

Plans say the building could be 170,000 square feet. There also would be 850 parking spaces and a gas station with 30 pumps. In all, the business would cover almost 37 acres.

New roads are expected to be built around the development. The first would be called 91st Avenue SE, and connect to 20th Street SE. The other would be called 24th Street SE, and link to Highway 9 with a roundabout.

Estimates show that nearly 800 cars would be in the area at peak evening traffic times.

“At least drivers who are there would go to that site,” Wright said. “It doesn’t necessarily mean there will be new people.”

It’s been about a year since Costco first showed interest in moving to Lake Stevens. The city and other agencies have been studying the area since then.

Wetlands on the lot are being reviewed by the city, in coordination with other affected agencies, Wright said.

It’s not clear yet how the project could impact those habitats, or what measures would need to be taken to preserve them.

Costco doesn’t comment on new locations until they are about three months from development, a company spokeswoman said.

Costco Wholesale has four Snohomish County stores — in Smokey Point, Everett, Lynnwood and near Woodinville. There also is a smaller Costco Business Center in Lynnwood.

Stephanie Davey: 425-339-3192; sdavey@heraldnet.com; Twitter:@stephrdavey.