BELLINGHAM — Small expansions are OK, but the city’s nine oversized big-box stores can’t build large additions to become superstores, the City Council ruled Monday.

Rejecting Costco Wholesale’s request to change the law to allow expansions of up to 20 percent, the City Council voted to allow oversized stores to add only 2,000 square feet. The change applies only to the nine existing stores larger than 90,000 square feet: Macy’s, Target, Kmart, both Fred Meyer stores, Home Depot, Costco Wholesale, Lowe’s and Wal- Mart.

The city’s ban on stores larger than 90,000 square feet, approved by the council more than a year ago, would still block new big-box stores.

Costco told city leaders it wants to add 1,500 square feet to its 133,000-square-foot store to install new refrigeration equipment, allowing it to store more products and reducing the need for additional truck deliveries. But, seeing that the store may want to expand more in the future, Costco officials asked city leaders to allow expansions of up to 20 percent, similar to what other Washington state jurisdictions allow.

That would have allowed it to add nearly 27,000 square feet, and the Bellingham Wal-Mart, for example, to add nearly 32,000 square feet to its roughly 160,000-square-foot store.

On Monday, City Council members voted 5-2 to tell staff to bring back an ordinance allowing 2,000-square-foot expansions. Council members Barbara Ryan and Jack Weiss voted against the recommendation, both opting for no expansion. The council must still approve the ordinance.

Many people who spoke at a public hearing Monday opposed allowing expansions.

“We must continue to maintain a level playing field for locally owned businesses and protect the vitality of downtown Bellingham,” said Charles Law, saying expansions would lead to more congestion, noise and environmental impacts from stormwater.

Others pointed to the sales taxes the stores generate for the city, and the flexibility retailers need to stay competitive.

“What Costco is asking you tonight for is the flexibility that it needs to keep its business viable in Bellingham,” said Seattle-based attorney Patrick Mullaney, who represents Costco. “Costco has been in the community for 15 years. It has a store that is currently substandard in size.”

The nine oversized stores paid $2.75 million in sales taxes to the city from September 2005 to August 2006, representing 15 percent of the total sales tax collected, according to a city staff report.

The Planning Commission had recommended allowing an expansion of up to 10 percent, and city planners recommended rejecting all expansions.

Planning Director Tim Stewart said staff will return the ordinance to the council at either the June 23 or July 14 meetings.