GREELEY, Colo. -- A group of environmental advocates is suing a Greeley beef company for allegedly polluting the South Platte River.

JBS Swift Beef is required to treat its wastewater from the thousands of animals it slaughters each day. Permits limit the amount of ammonia, fat and excrement that can be released into local waterways.

"For the past four years JBS has been in violation of the Clean Water Act permit. Essentially, they have been dumping more into Lone Tree Creek than they should, or (dumping) things they shouldn't be dumping," Tyler Van Kirk with Food & Water Watch told Denver7 Wednesday.

The water from the creek flows into the South Platte River.

The lawsuit points to Environmental Protection Agency (EPA) reports which show the company has not been in compliance going back to 2014.

“The best end result is they clean up their act," said Van Kirk. "They’ve been out of compliance for four years, they have (had) every opportunity to do that; they aren’t going to do it out of the goodness of their hearts, (so) the goal of this lawsuit is to get them to follow the law.”

JBS sent us a statement saying they are in the process of improving their water treatment process:

“We are committed to being good neighbors in the communities in which we operate. That includes a focus on water quality at our Lone Tree wastewater treatment facility. We recently invested a significant amount to buy and install new blowers that provide oxygen to the wastewater treatment process, allowing us to further improve our processes and ensure compliance. We’ve seen strong performance of the treatment process in recent months, and we work closely with the state of Colorado on an ongoing basis.”

Environmental groups hope their lawsuit pushes JBS to get in compliance.

Officials with the Colorado Water Quality Control Division say they are aware of the violations and have been working with JBS to resolve it. They say JBS has been in compliance with the terms of its discharge permit since January.