Seattle: When it rains, it pollutes

When rain falls in undeveloped areas, water is absorbed and filtered by the soil and plants. But in built cities like Seattle, water washes over rooftops, roads and sidewalks, picking up a cocktail of pollutants on its way: gasoline, tire particles, heavy metals, pesticides and even animal droppings. Most of it ends up passing directly into the Puget Sound, transforming the city’s waterway into a house poisonous to marine life.

This week, Down to Earth meets a diver, a filmmaker and now an activist defending local efforts to save Seattle’s Puget Sound.

In addition, a renowned aquatic ecotoxicologist from Washington State University explains why coho is an important sentinel for the dangerous effects of rainwater.

Finally, we explore how new types of building constructions that mimic nature could help filter pollution, an idea that can be replicated in cities around the world.