A memo laying out the changes came one day before companies and individuals could stake mining claims in national monuments.
Zinke faces anger from governors, including many Republicans, over proposals to allow more drilling on land and at sea.
“The risks of fracking to our health and our environment are real,” California Attorney General Xavier Becerra said Wednesday.
The Interior Department rescinded a set of Obama-era regulations that would have tightened standards for fracking operations on public lands to protect waterways.
Pregnant women living within a two-mile radius of drilling sites were more likely to have babies with low birth weights.
The Trump administration will delay an Obama-era rule limiting methane emissions.
The plan to offer nearly 77 million acres in the Gulf of Mexico for oil and gas leases is the largest in U.S. history.
The Trump administration is working to promote development by weakening environmental laws and public access to government information, according to reports from an invitation-only meeting.
"I got 30 percent of the crew that’s not loyal to the flag,” Interior Secretary Ryan Zinke said in an address to the oil industry.
The project had previously been rejected during the Obama administration.