The Environmental Protection Agency (EPA) has introduced a proposed rule to eliminate all diesel exhaust fluid (DEF) deratements, offering significant regulatory relief to agricultural producers and the trucking industry. Farm Director KC Sheperd recently spoke with EPA Region 6 Administrator and fifth-generation Oklahoman Scott Mason to discuss the agency’s efforts to address ongoing concerns regarding DEF, emissions regulations, and water policy.
Addressing DEF Concerns and Deratements
In a conversation with Farm Director KC Sheperd, EPA Region 6 Administrator Scott Mason—a fifth-generation Oklahoman from Washita County—highlighted the agency’s response to feedback gathered from the agricultural and transportation sectors.
“This administration under President Trump and Administrator Zeldin are really leaning in, listening, and delivering,” Scott Mason said. “You recall our roundtable conversation last May out in Burns Flat, Oklahoma, where we had a lot of members from the farm and ranch community really represented where we said, ‘What waterways can EPA assist you and help you out?’ And the number one topic that day was please do something about DEF, diesel exhaust fluid.”
“I heard that loud and clear,” Scott Mason said. “Administrator Zeldin has now heard that in his travels to all 50 states loud and clear. President Trump has heard that loud and clear. And so, we have started working incrementally over the last year on addressing these issues that farmers, ranchers, truckers have been dealing with on DEF.”
Mason explained the details of the proposed rule and how it aims to change vehicle operations when DEF levels are low.
“We are taking this as far as the law will allow us to, and so I’m very proud to say that last week, we came out with a proposed new rule to eliminate all DEF deratements entirely,” Scott Mason said. “So, what does that mean? Essentially, going forward—well, we’re currently in a 45-day comment period, so we encourage any person who’s listening to this, go online to epa.gov, comment, make your thoughts, your concerns, your ideas heard. We will read through every one of those comments, and at the end of that 45 days, if we need to, based on the comments we’ve received, we will modify our proposed rule.”
“But our proposed rule would do away with all DEF deratements,” Scott Mason said. “So that means that now, instead of getting a deratement, you would just have an audible sound maybe that comes on in the cab of your tractor or your truck going forward to alert you that you’re low on DEF and you need to refill it with DEF, or maybe it’s something similar to a check engine oil light or low fuel light that comes on in your vehicle.”
“Whatever that looks like, the person driving the diesel-powered vehicle no longer have to worry that they’re going to go into a deratement of total shutdown or 15–20 miles an hour or something like that,” Scott Mason said. “They’re going to have time now to take it in on their own time and resolve the DEF issue and not be at the whim of the engine. So, this is extremely positive news. We’ve been working with farmers, ranchers, truckers, manufacturers on this for the last year, really trying to fine-tune this, and it’s led us to where we’re at now in this proposed new rule, KC.”
Emissions Requirements and Regulatory Certainty
Farm Director KC Sheperd asked about future expectations regarding emissions requirements for agricultural equipment.
“One thing that producers always talk to us about, and I hear it loud and clear—and it’s really across any kind of genre of industry—is please provide regulatory certainty,” Scott Mason said. “And we’re doing that with this. And I would also note that EPA is also specifically proposing to scale back the emissions warranty requirements that added the largest single cost to the trucking industry because truckers have been hampered by this just like farmers and ranchers.”
“Under this proposal, the Trump EPA would then maintain the underlying emissions standards, including a nearly 90% of the nitrous oxide or $NO_x$ reductions, while also sparing Americans from unnecessary warranty costs,” Scott Mason said. “Once again, our Trump EPA is demonstrating that environmental protection and economic prosperity does not need to be a binary choice. You can do more than one thing at a time.”
WOTUS and Supreme Court Compliance
Farm Director KC Sheperd also inquired about the agency’s position on the Waters of the United States (WOTUS) definition following judicial decisions.
“Since the Supreme Court’s Sackett decision, where does EPA stand on WOTUS, and what should farmers really know about that?” Farm Director KC Sheperd asked.
“Great question, and something we’re hearing a lot about right now,” Scott Mason said. “We have had listening sessions and roundtable discussions on WOTUS for the last several months, and so our headquarters team is still working on that. Know that this agency will come up with a proposal that does have a proposal that is durable, it is clear, it is concise, and it is in line with the Supreme Court’s decision on Sackett.”
“So, we’re still working on it, but it will be something that follows the law and is clear, and it is durable,” Scott Mason said. “It is in plain English. No longer will you have to determine if your stock tank—as I often like to say at my farm in Western Oklahoma—is not a waters of the United States. So, it will be a definition that is clear, concise, and durable and stand the test of time and the law.”
Pesticide Application Backlog
Addressing questions regarding pesticides and endangered species guidelines over the coming year, Mason indicated ongoing agency action.
“The EPA at headquarters continues to comb through our pesticides backlog,” Scott Mason said. “We have had a tremendous backlog, and I’m proud to say that this agency has leaned into that, and we are continuing to work on that, and I think there’s a whole lot more to come there, so stay tuned.”
“Scott, always thank you for representing not only just Oklahoma, but Western Oklahoma,” Farm Director KC Sheperd said. “We’re glad to have you where you’re at right now. Thank you so much for visiting with us today.”
“Always proud to represent Oklahoma wherever I go,” Scott Mason said. “I appreciate your time today, KC, and say hello to all my friends and everyone listening in Western Oklahoma and throughout the state of Oklahoma.”
