"Mossville, Louisiana -- As the Environmental Protection Agency vans roll from one home to the next, each one marked with a red dot on a map, Dorothy Felix tags along like a proud parent.

At each stop, EPA investigators collect potentially tainted water from the kitchen tap and possibly toxic soil samples from the yard.

"This is a very important day. It's a day that should have come a long time ago. We have traveled a long journey and I feel like victory is close," Felix says, smiling.

Nearby, an EPA contractor uses a hand trowel to scoop hard-packed dirt into glass jars for testing at a government lab in Houston, Texas.

Felix and other environmental activists in this southwest Louisiana community tried for decades to convince the state and federal governments they live in a toxic town."

David S. Martin, Dr. Sanjay Gupta, report for CNN June 2-3, 2010. The second installment will air June 3 at 8 pm ET. [2]