The letter was dated Thursday and confirmed Friday by Corbett's office. On Tuesday, President Obama presented his climate-action plan, praising natural gas as a valuable "bridge fuel."
Industry applauded, and drilling opponents countered that natural gas was more of a "gangplank."
The commission governs water quality and quantity in the basin. States with land in the basin - Pennsylvania, New Jersey, Delaware, and New York - are members, along with a federal representative. The river provides drinking water for 15 million people.
After enacting a ban three years ago, the commission devised and proposed rules. But a vote scheduled for November 2011 was abruptly canceled when Delaware Gov. Jack Markell withdrew his support.
New York also was deemed a "no" vote because officials wanted to complete their own environmental and health assessments, still going on.
Since then, "there have been ongoing deliberations regarding science and best management practices and how to strike the appropriate balance regarding development of natural gas and protection of public health and natural resources," said Robert Tudor, deputy executive director of the commission.
New Jersey officials said they had only just received Corbett's letter. But a spokesman said the state's position had not changed: "Protection of the Delaware River Basin is most vital and most important."
He said the commission had been awaiting results of a U.S. Environmental Protection Agency study of hydraulic fracturing, a technique used to extract the gas.
Delaware officials declined to comment, and New York officials did not respond to a request for comment.
Bob Rutledge, president of the Northern Wayne Property Owners Association, said he was "thrilled Gov. Corbett finally stood up for us."
"It sends a message to the other governors," he said. "It's time for them to stop playing politics and do what they know they have to do, which is end the moratorium and let drilling proceed."
The Marcellus Shale Coalition, an industry group, also welcomed the governor's action.
For three years, "while the DRBC stalled and stood in the way of landowners making decisions with respect to their private property, Pennsylvania has modernized and strengthened environmental safeguards," said Kathryn Z. Klaber, the coalition's chief executive. "The DRBC should not delay any longer."
Corbett said that because of the DRBC's inaction, "operators interested in developing natural gas have closed offices and laid off employees, lease payments have been withheld . . . and communities have watched their neighbors outside the basin benefit tremendously."
He said continued inaction might constitute an illegal "taking" of property.
Maya van Rossum, the Delaware riverkeeper, mocked Corbett's assertion that he was writing on behalf of his constituents.
"Gov. Corbett has made very clear . . . that his constituents are the gas drillers," she said. "That's not the appropriate role of the governor."
She said state law still had inadequate environmental protections. The commission is doing what it is "supposed to be doing - protecting the community, not sacrificing the community for the benefit of a limited few," she said.
Contact Sandy Bauers at 215-854-5147, firstname.lastname@example.org, or follow on Twitter @sbauers. Read her "GreenSpace" blog at www.inquirer.com/greenspace.