Pennsylvania's experience with shale-gas drilling has given the Delaware River Basin Commission plenty of reason to take a long and careful look before letting the rigs set up shop in the region's most important watershed.

Gas wells bring up millions of gallons of water that carries high levels of radioactivity. Air pollution builds up as drilling rigs and diesel trucks and huge gas-pumping compressors proliferate. Pipelines spread across the land, even where landowners don't want them to cross.

There are questions about how much methane gas leaks into the air from drilling and pipelines - a significant concern, since methane is a powerful greenhouse gas.

But the biggest threat is what all the drilling may be doing to nearby drinking water. Where drilling takes place, residents routinely report their water wells are turning up methane gas and other contaminants.

It's become common in shale-gas country to see "water buffaloes," trucks that haul in clean drinking water. Pennsylvania law presumes that gas drilling causes any well-water contamination that shows up within a thousand feet.

A study led by Duke University researcher Robert Jackson published in May found three places in Pennsylvania where it appeared gas from deep shale drilling was leaking into water wells close to the surface.

Despite the wide range of obvious environmental impacts to drilling, the Delaware River Basin Commission has declined to do a formal environmental impact study. The multistate commission is an orphan agency that doesn't have its own funding source and is chronically strapped for money.

Seeing all that, several conservation groups filed suit Thursday to force the commission to do an environmental impact study. It looks as if federal lawyers will respond by saying the commission is not officially a federal agency covered by the federal law that requires an impact statement.

That's the kind of lawyerly technicality that might carry the day in court, but it would be unfortunate if it did. An environmental impact study is essential to answer critically important questions, and it shouldn't take a court order to make it happen.