SIOUX FALLS, S.D. (AP) — The Sioux Falls Regional Landfill was considered ahead of the curve five years ago when it installed a system to capture gas given off by decomposing trash and turn it into energy.

But the landfill's operators have now joined others who oppose proposed federal regulations that would require large landfills to control methane gas emissions.

Landfill Superintendent Dave McElroy tells the Argus Leader the rules could require upgrades to the landfill's system, and it might jeopardize a financial incentive it collects for voluntarily reducing emissions.

The Poet ethanol plant near Chancellor pays Sioux Falls $2 million annually for the gas, and $150,000 annually for the carbon credits the city earns for voluntarily curbing emissions.

Federal officials are expected to make a decision on the proposed new rules by April.

Copyright 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.