Environment

Few people know the orcas of Puget Sound as well as Ken Balcomb.

A researcher with the Center for Whale Research on Washington state's San Juan Island, Balcomb has been studying the whales for more than 30 years.

It takes Balcomb only a few seconds of listening to the squeaks and whistles of underwater whale recordings to recognize the different pods of orcas.

In one recording, Balcomb identifies the group known as the L Pod — the family many people in the area are talking about right now.

Orca L112, also known as Victoria, was a 3-year-old L Pod female who washed up dead on the Washington coast in February.

Quite a few of the 225 people who live in Dish, Texas, think the nation's natural gas boom is making them sick.

They blame the chemicals used in gas production for health problems ranging from nosebleeds to cancer.

And the mayor of Dish, Bill Sciscoe, has a message for people who live in places where gas drilling is about to start: "Run. Run as fast as you can. Grab up your family and your belongings, and get out."

But scientists say it's just not clear whether pollutants from gas wells are hurting people in Dish or anywhere else. What is clear, they say, is that the evidence the town has presented so far doesn't have much scientific heft.

'This Place Was Absolutely Beautiful'

A proposed study of people in northern Pennsylvania could help resolve a national debate about whether the natural gas boom is making people sick.

The study would look at detailed health histories on hundreds of thousands of people who live near the Marcellus Shale, a rock formation in which energy companies have already drilled about 5,000 natural gas wells.

If the study goes forward, it would be the first large-scale, scientifically rigorous assessment of the health effects of gas production.

Secret Weapon: A Very Large Database

Living in the middle of a natural gas boom can be pretty unsettling. The area around the town of Silt, Colo., used to be the kind of sleepy rural place where the tweet of birds was the most you would hear. Now it's hard to make out the birds because of the rumbling of natural gas drilling rigs.

The land here is steep cliffs and valleys. But bare splotches of earth called well pads are all over the place.

"That's the one I'm worried about because it just went in," says Tim Ray.

We're on his front porch just after sunset. You can see the lights of drill rigs all around his small house.

"There's actually one up here over the hill that they just put in." He points in another direction: "There's three or four of them up there."

In Pennsylvania, there's an industrial revolution going on. Battalions of drilling rigs are boring into the earth to extract natural gas from an underground layer of shale called the Marcellus formation.

And as the wells multiply all along the western end of the state, people worry they may be facing another toxic legacy.

The first one came from coal mining. All over the state, you can see bright orange rivers and streams. The aquatic life was killed by acidic runoff from abandoned mines.