LINCOLN, Neb. (AP) — Lincoln’s year-old cardboard ban has led to a 76% drop in the amount sent to the city landfill but the diversion comes with raised costs for the city.

The decline in corrugated cardboard at the city’s landfill is estimated to have saved 239,360 trees, 30 million pounds of carbon dioxide emissions and 1.5 million gallons of gas, the Lincoln Journal Star reported.

Cardboard made up 2.4% of the waste entering the landfill last year, down from 9.4% in 2017, according to Donna Garden, assistant director of Lincoln’s Transportation and Utilities Department.

Garden wrote in a report to city officials that Lincoln’s public recycling sites have seen the amount of cardboard dropped off by residents double since the ban took effect last April. But the cost of running those 29 drop-off sites has also doubled.

Lincoln expects to pay about $900,000 a year to Von Busch Refuse to haul away recyclables from the public sites, Garden said.

Costs are partially offset by revenue from selling the cardboard, but returns have dropped due to changing markets and processing companies paying less for the material. Lincoln made roughly $295,000 from the material’s sales in fiscal year 2016-2017. Garden projects the city’s annual revenue from cardboard will be around $217,000 for a full fiscal year.

The city’s Transportation and Utilities Department plans to consider expanding the landfill ban, Garden said.

The ordinance was originally part of a broader effort that would’ve eventually banned all paper, but Mayor Chris Beutler could only get City Council approval for cardboard.

The issue was recently debated by two candidates running for mayor in the May 7 election.

Candidate Cyndi Lamm believes that Lincoln shouldn’t have “mandated recycling to begin with,” while opponent Leirion Gaylor Baird said she would look for bipartisan support to expand the landfill ban.