Nonpoint Pollution Source (NPS) pollution is defined as pollution that comes from many diffuse sources. NPS pollution is caused by rainfall or snow melt moving over and through the ground. As the runoff moves, it picks up and carries away natural and man-made pollutants, finally depositing them into lakes, rivers, wetlands, coastal waters, and even our underground sources of drinking water. If we all do our individual parts in reducing nonpoint source pollution, together we can greatly improve the conditions of our lakes, rivers, and wetlands.