Our water has gotten a lot cleaner in the last few decades as we increased regulation of industial pollution. But recently, progress stopped. Scientists think that's because we've underestimated one huge source of pollution -- everything that washes off the ground when it rains. Altogether it’s called “nonpoint pollution,” because it doesn’t come from one point source, like a drainage pipe from a factory. It comes from all over – your neighbor’s lawn, the baseball field down the street, or the farm you pass on the highway. And it might be causing more problems than we know. 

California is dealing now with the issues scientists say New England will face more often in the next century -- as glaciers melt, oceans rise, and the seas claim more coastline.  The California coast is sandier than back East; and the waves are more powerful. So erosion is much farther along here. But lost apartment buildings like these in Pacifica taught California officials a valuable lesson: It’s easier – and cheaper -- to prepare rather than react to the incoming seas.