At a time when natural-gas drilling poses a threat to so many Pennsylvania communities' rivers, streams, lakes, and drinking-water supplies, Harrisburg lawmakers cannot permit the state's open-space and environmental cleanup effort to run dry.

Yet, the Growing Greener initiative — a signature program launched by Republican Govs. Tom Ridge and Mark Schweiker — is running perilously close to the edge on its funding.

A GOP successor, Gov. Corbett, has proposed an austere state budget that would mean annual grants under Growing Greener would decline precipitously. While around $150 million has been available in each of the last six years, annual grants under the Corbett plan would drop nearly 82 percent, to $27.3 million.

That said, Corbett inherited the fiscal plight facing Growing Greener. Trash-dumping fees meant to recharge the fund were diverted to cover debt service in recent years. Former Gov. Ed Rendell was a proponent of Growing Greener, but left office without reaching a deal with lawmakers on added funding.

The new governor's no-tax pledge, however, has put the state in a bind. In order to free up the trash-tipping fees for new projects to preserve open space, perform stream and other watershed cleanups, and reclaim brownfield sites in urban communities, new revenues would have to be found — all without raising anyone's taxes, according to Corbett's governing philosophy.

Fortunately, a coalition representing 250 organizations and government entities — the Renew Growing Greener Coalition — is keeping up public pressure to push the envelope in tax-averse Harrisburg.

Despite Corbett's pledge, the most obvious solution would be to join every other state that has a natural-gas industry and impose a tax on the drillers exploring the huge Marcellus Shale formation.

In February, state Rep. Greg Vitali (D., Delaware) offered a sensible plan that would impose a gas extraction tax and devote a third of the revenue to Growing Greener. Significantly, Senate President Pro Tempore Joe Scarnati (R., Jefferson) has offered support for that concept, and may offer a majority-party plan on a shale tax.

With or without a tax on drillers, Corbett's state Department of Environmental Protection must crack down on any threat to watersheds. But imposing a shale tax that funds the open-space and cleanup efforts of Growing Greener would be a smart strategy to preserve the livability of communities across the state.