Water from rain and melting snow either seeps into the ground or runs to lower areas, making its way into streams, lakes and other water bodies. On its way, runoff water can pick up and carry trash, debris and many substances that pollute water.
Some substances in the runoff—such as pesticides, fertilizers, oil and soap, dirt, pet waste, grass clippings and leaves—are created by human activity and can harm the Rio Grande.
In addition to rain and melting snow, various activities like watering and car washing can also put water onto the land surface which can carry pollution to our river.
Polluted runoff generally happens anywhere people use or alter the land. In developed areas, the water that falls on hard surfaces like roofs, driveways, parking lots or roads cannot seep into the ground. These impermeable surfaces create large amounts of runoff that can easily pick up debris, substances and dirt. Also, the runoff can erode stream banks. The mix of pollution and dirt muddies the water and causes problems downstream.