On Thursday, the Louisiana Department of Wildlife and Fisheries said that a growing number of birds with oil-drenched feathers had been spotted around the area of the Phillips 66 Alliance Refinery, in Belle Chasse, Louisiana.
Among the affected birds are black-bellied whistling ducks, blue-winged teal and various egrets. Alligators, nutria and river otters were also found soaked in oil.
Jon Wiebe, a biologist with the state's restoration programme, told the Associated Press that at least 10 oiled birds were captured and sent to a rehab location, and five others - which were found dead - were collected as evidence.
The Environmental Protection Agency said it received 43 reports of substantial inland oil and chemical spills in the wake of Hurricane Ida. The agency is seeking reports from facility operators to determine if any federal environmental laws were broken during the storm.
The AP reported on 1 September that a spill occurred at that refinery after it was battered by Hurricane Ida. According to the AP, the Phillips 66 refinery repeatedly tried to downplay the reports of the damage at the facility.
Bernardo Fallas, a spokesman for the refinery, told the AP there had been "some water" in the facility but said that all operations had been shut down ahead of the storm.
When another reporter asked Mr Fallas if any environmental hazards had originated from the facility, he referred them to the company's website, where it says it will ensure "the safety and well-being of our employees and our surrounding communities."
The AP reported that it sent Mr Fallas aerial photos of the facility which contained evidence of substantial flooding as well as petroleum in the water. Mr Fallas then reportedly said the company had found a "sheen of unknown origin in some flooded areas" and that the contaminants had been "secured and contained within refiner grounds."
An assessment team from the Louisiana Department of Environmental Quality was dispatched to the refinery last week to inspect the spill. According to the team, the oil spill was substantial and the company was using booms and absorbent pads to soak up the pollution.
The team also found that a nearby levee, which was meant to protect the plant from flooding, had breached during the storm. The water unleashed on the plant after the levee fell appears to have flooded the facility.
The Independent has reached out to Philips 66 for comment.
There is no estimate yet as to the extent of the oil spills caused by Hurricane Ida.