As of Thursday morning, the commission also had received more than 7,600 comments either on paper or through a software portal specially adapted for submissions.
Those alone were far more than the commission had received on any issue in recent memory, a spokesman said. Nor was it a surprise: The DRBC had nixed submissions by e-mail, fax, and telephone in order to handle the deluge.
"The level of organization response, community response, public input, comments, and letters vastly outnumbers anything they've experienced or had to deal with, and that's appropriate," said Delaware Riverkeeper Maya van Rossum.
"This is one of the biggest threats facing the Delaware River certainly in our lifetime, and well into the future," she said.
While drilling has continued in the rest of Pennsylvania underlain by the gas-rich Marcellus Shale formation, the commission - an interstate agency that oversees water quality and quantity in the basin - has declared a moratorium until regulations can be adopted.
New Jersey, Pennsylvania, Delaware, and New York each have land in the basin, and each has one representative on the commission, as does the federal government.
Delaware and New Jersey have no Marcellus Shale formations. New York does, but it also has a moratorium in place until an environmental impact study is completed.
Much of the waters upstream of Trenton are so pristine that they have warranted extra federal protection.
The commission proposed natural gas drilling regulations, which are generally stricter than those in the rest of Pennsylvania, in December. Potential contamination of water supplies has been a concern, since the Delaware River provides drinking water for 15 million people, including Philadelphia and several suburban areas.
The industry, which says drilling is safe for the environment, has said the new regulations are unworkable, too restrictive and in some areas duplicate what Pennsylvania already regulates.
Environmental advocates have criticized the commission for proceeding with regulations before a cumulative environmental impact study. They say the regulations are inadequate to protect the river from pollution.
In recent days, environmental groups have marshaled an intensive information campaign and volunteer effort.
One of the Delaware Riverkeeper Network action alerts showed a person in a hazardous materials suit tubing down the Delaware.
Randy Sklar and Celeen Miller, who live in Perkasie, hosted a forum so people could make more thorough comments.
With several events planned for Thursday night, the groups said they expected to deliver hundreds more comments on Friday. Online comments may be submitted via www.state.nj.us/drbc, the site says, "until 11:59 p.m. Mountain Time on April 15."
Meanwhile, organizations were putting the finishing touches on their own comments, many of them highly technical and lengthy.
The Marcellus Shale Coalition, an industry group, submitted a 13-page letter "on behalf of the coalition's nearly 180 member companies, who employ thousands of Pennsylvanians committed to the responsible development of clean-burning, job-creating American natural gas," said spokesman Travis Windle.
The coalition also submitted a 12-page technical analysis by an Oklahoma engineering and environmental consulting company.
Maya van Rossum said her Riverkeeper group's submission was 174 pages, not counting the eight reports it commissioned from experts in such areas as storm water, contamination, seismic issues, and water use.
The commission now will organize the comments and prepare a response, said spokesman Clarke Rupert.
He said the paper comments were being scanned into the software system by an independent contractor so they could be organized.
"They will all be read through and given consideration," he said. The comments are public record and, as such, will be available for inspection at some point.
"It comes down to a logistics issue," Rupert said. "It's certainly going to take some time."
Officials have said the earliest the commission would act would be its regularly scheduled meeting on Sept. 21.
Contact staff writer Sandy Bauers at 215-854-5147 or email@example.com Visit her blog at http://go.philly.com/greenspace