President Donald Trump pointed to farmers Monday as winners from the administration’s proposed rollback of federal protections for wetlands and waterways across the country, describing farmers crying in gratitude when he ordered the change. But under long-standing federal law and rules, farmers and farmland already are exempt from most of the regulatory hurdles on behalf of wetlands that the Trump administration is targeting. Because of that, environmental groups long have argued that builders, oil and gas drillers and other industry owners would be the big winners if the government adopts the pending rollback, making it easier to fill in bogs, creeks and streams for plowing, drilling, mining or building. Government numbers released last month support that argument.Real estate developers and those in other business sectors take out substantially more permits than farmers for projects impinging on wetlands, creeks and streams, and they stand to reap the biggest regulatory and financial relief from the Trump administration’s rollback of wetlands protections.