The Environmental Protection Agency's draft rule for post-construction stormwater runoff—originally expected to be released by a court-ordered date of June 10, with final action by June 2014—could be facing some hurdles.

All eight Republicans on the Senate Environment and Public Works Committee have asked EPA's acting assistant administrator for the Office of Water, Nancy Stoner, to delay releasing the proposal, saying the planned rule-making is "clearly inconsistent" with the Clean Water Act and that the agency has failed to allow small businesses to participate in the development of the rule.

Moreover, in a May 20 letter, the group of lawmakers, led by Sens. David Vitter (R-La.) and James Inhofe (R-Okla.), said the EPA has failed to provide Congress with sufficient explanation as to why the new stormwater discharge regulations are necessary.

The EPA did not respond to ENR's requests for clarification on the status of the rule, but several industry sources note the rule already has been delayed more than once and that the release date was behind schedule even before the senators' letter.

The EPA has released few details on what the proposal, which would fall under the national pollutant-discharge-elimination permitting system, would entail. But environmental advocates and industry sources alike say it would be the first regulation to set controls for stormwater runoff from development sites after construction has been completed.

Leah Pilconis, senior environmental adviser to the Associated General Contractors of America, says a proposal could require builders that disturb a certain amount of land to retain a percentage of stormwater on-site. "What percentage that could be could vary depending on whether it is a redevelopment or a greenfield site. … But nobody has seen any of those numbers," she says.

However, such a proposal would go "completely beyond what contractors are currently required to do" under current federal regulations, Pilconis says. The measure likely would incur significant cost as well as legal ramifications for contractors.

Environmental groups, such as the Natural Resources Defense Council (NRDC), say the regulation could present an opportunity to improve the quality of the nation's waters by creating incentives for green infrastructure on a national scale and reducing costs to communities. NRDC says cities such as Philadelphia and Cincinnati have launched major green infrastructure projects and initiatives that will save the cities billions over the next two decades.

But some industry groups balk at requiring green infrastructure on a national scale. Ty Asfaw, environmental policy analyst for the National Association of Home Builders, says that, based on where EPA "could be going, there are some concerns over initially putting in green infrastructure and LID [low-impact development] as opposed to traditional gray infrastructure" on a widespread scale. Asfaw says the long-term effectiveness of green infrastructure has not been proven and that costs for its long-term maintenance could be higher than for gray infrastructure.