Maybe a trash cart will be the newest look for Halloween in Lawrence.

City commissioners on Tuesday took their largest step yet to create a trash system that mandates the use of city-issued carts instead of standard trash cans or bags.

Commissioners unanimously agreed to seek bids to purchase more than 20,000 trash carts, and said that if all goes well, the carts could be in place by the end of October.

But commissioners still have one major issue left to answer before finalizing the program: cost.

City staff members are recommending a system where trash rates stay the same for most residents and are reduced slightly for about 7,000 other households. But commissioners said they wanted to be presented with an option that would reduce rates for a larger number of customers, especially those customers who generate very little trash.

“I think we want to encourage smaller amounts of trash to be put out,” said City Commissioner Mike Amyx. “But I think we really have to create an incentive to do that.”

Commissioners at their weekly meeting said the cart system may allow them to create such an incentive. As proposed the cart system would offer three sizes of carts for households. A 65-gallon cart would be the standard size, a 90-gallon cart would be issued for larger producers, and a 35-gallon cart would be available for generators of small amounts of trash.

But under the current proposal, households that sign up for the 35-gallon cart will pay the same price as someone who has the 65-gallon cart.

Several residents told commissioners on Tuesday such an arrangement wasn’t fair.

“A reduced rate for reduced trash would be a useful slogan for the city to adopt,” said Bill Mitchell, a Lawrence resident who estimated his household sets out only about 5 gallons of trash per week.

Commissioners said they wanted to see a financial analysis of how the city could issue a discount for residents who use the smaller cart. Staff members said they would produce the analysis within the next two weeks, but also expressed concern about offering an immediate discount for the 35-gallon cart.

Tammy Bennett, assistant director of public works, told commissioners a discount may cause many people to choose the 35-gallon cart when the amount of trash they generate is more suitable for a 65- or 90-gallon cart. The result could be, she said, large numbers of trash bags left beside the new carts. The city is trying to eliminate people using cans or bags for their trash because it makes it difficult for the city to use automated trucks, which the city says will reduce worker compensation costs and make the system more efficient.

Under the staff-recommended plan, about 7,000 households that currently rent a cart from the city would see their monthly trash rate decline. Here’s how:

• Households that currently rent a 65-gallon cart from the city pay a $1.50-per-month fee for the cart. Under the proposed system that monthly fee would be eliminated.

• Households that currently rent a 90-gallon cart from the city pay a $2-per-month fee for the cart. Under the proposed system that fee would be reduced to $1 per month.

Commissioners did hear from one member of the public who urged the city to put the cart plan on hold and instead study whether the city ought to turn the trash system over to a private operator.

“I think you are getting the cart before the horse here,” said Jim Mullins, a Lawrence resident and a field director for Americans for Prosperity.

Commissioners on Tuesday did not have any discussion about privatizing the city trash service.

In other news, commissioners did discuss creating a curbside recycling system. Commissioners on a 5-0 vote approved a “resolution of intent” that formally declares the city will study options for a citywide curbside recycling program.

But commissioners did not discuss any of the major details related to a curbside program, and also noted the resolution does not commit the city to start a curbside program. But the resolution does give staff members the authority to spend the next 90 days working on a request for proposals that could be sent to private companies interested in operating a citywide curbside recycling system.