“It has come to our attention that the EPA is informing agriculture producers that it does have the authority to begin enforcing the SPCC rule retroactively beginning September 23,” the senators wrote in a letter to McCarthy. “Congress has repeatedly raised concerns about the implementation of this rule within the agriculture sector, making these reports particularly unsettling.”

Pryor and Inhofe have argued that the SPCC regulations — designed to protect the environment — would be too burdensome for farmers. To comply with the SPCC rule, farmers would be required to install new double-walled engine oil and diesel storage containers, build berms around their storage facility locations, and submit paperwork that must be certified by professional engineers proving their farm is in compliance with the rules.

“Congress has clearly established its intent to limit the impact of the SPCC rule on the agricultural sector, and to ultimately exempt the majority of it from having to comply,” the letter stated.

Earlier this year, Inhofe and Pryor successfully amended the Water Resources Development Act (WRDA). Their amendment permanently exempted most farmers from the SPCC rule. The House hasn’t passed the WRDA bill, but added a similar provision to its farm bill.

“If the agency does plan to retroactively enforce the rule, will you please explain why you are doing this despite the clear, bipartisan steps Congress has taken over the past few months to limit this rule's impact on the agriculture community?” the senators wrote.

The EPA said Thursday that the agency has not investigated "the SPCC compliance status of any owner or operator of a farm." Under the 2013 continued spending resolution (CR), Congress prohibited the EPA from using funds to inspect, seek information or investigate SPCC compliance of farmers until after Sept. 22 — the fiscal year ends on Oct. 1. The EPA said it is in full compliance with the CR.

This article was updated at 1:30 p.m.