Home to a vast variety of plants and wildlife, the Delaware River basin which stretches 14, 000 square miles across four states is extremely valuable to humans.

The river and its watersheds provide drinking water to millions of people.

It's a vital economic resource but for much of the last century, the section of the Delaware River around Camden and Philadelphia was a foul mess full of sewage, chemical waste and other byproducts of rapid urbanization.

At one point, the river was so contaminated, parts of it became uninhabitable for fish.

It was even dangerous to humans.

The river has been cleaned, though not completely, and new threats loom with a changing climate.

Rapid urban growth and encroaching development have contributed to declining wildlife populations and threatened the fragile ecosystem.

The excess use of fertilizers and industrial pollution have threatened the waterways that flow into the Delaware and as climate change brings about warmer temperatures extreme weather events and rising sea levels, every aspect of the river basins ecosystem is affected.

If the watersheds within this vast region don't remain healthy they'll be unable to keep the water clean, control erosion and reduce flooding.

In this special series "Water's Edge: the trials and tributaries of the Delaware River Watershed," our reporters explored the Delaware River Basin.

Speaking with experts conservationists and citizens.

We'll take you to four regions of the watersheds in New Jersey: the Highlands, the Pinelands, the Delaware Bayshore, and the urban Delaware region.

We'll examine the threats and challenges each region faces and why conservation efforts are so critical to the river's survival.

This is Water's Edge.