Unit 2: Stormwater

Be the solution to stormwater pollution!

Essential question: 

How does what we do on the land affect water quality? How does pollution get from one place to another? How can I learn about the sources of water pollution in my watershed?

Learning objective

Students will be able to: 

  1. Explain how various land uses can affect water quality. 
  2. Suggest best management practices to reduce water pollution. 
  3. Identify potential sources of pollution in the watershed.

Next Generation Science Standards:

NGSS Disciplinary Core Ideas (Grades 6-8)

  • MS-ESS2-Earth’s Systems
  • MS-ESS3 Earth and Human Activity
  • MS-LS2 Ecosystems: Interactions, Energy, and Dynamics

NGSS Science and Engineering Practices (Grades 6-8)

  • Defining and Delimiting Engineering Problems
  • Asking Questions and Defining Problems


The Pacific Northwest might be famous for its rain, but just where does all that water go? In nature, rain or snow can soak into the ground where trees, plants, and soil can absorb it and help to naturally filter pollutants. But hard, impervious surfaces, like roads, driveways, and rooftops do not absorb the water. Instead, the water flows across these surfaces, picking up pollution and chemicals along the way, before eventually going into storm drains. The storm drains take the water in pipes directly to our streams and rivers without pollution controls to filter or clean. The storm drain and the sewer system that carries waste from your house or school (which goes to a wastewater treatment plant for cleaning and filtration) are typically two different systems.

Too much stormwater can cause erosion and stir up sediment that impacts water quality and can smother fish eggs. Additionally, if too much water collects on a surface it could normally soak into, it can pool up and eventually flow into the road and to the storm drain. Typically, urban and suburban areas produce more stormwater because of the high amount of paved or impervious surfaces.

Stormwater can collect fertilizers, pesticides, and pet wastes from yards, parks, and farms; and grease, oil, and heavy metals from buildings, parking lots, and roads. It can flow across surfaces and directly into the river or into storm drains and pipes that discharge polluted runoff into the Columbia, negatively impacting water quality and potentially causing serious harm to aquatic life. To keep the Columbia clean, it’s critical to reduce stormwater pollution and prevent harmful chemicals, wastes, and pollutants from entering the river. Preventing stormwater pollution requires participation from the government, businesses, schools, community groups, and residents. We all have to do our part!

But what can you do?

You can help reduce the pollution that goes into stormwater by properly disposing of hazardous waste and garbage and limiting or avoiding the use of pesticides and fertilizers. Regular upkeep and maintenance of vehicles prevent dripping oil and gas, and if you’re washing a car, do it at a commercial car wash where the water is sent to a treatment plant. And, of course, always pick up after your pet. Communities can reduce stormwater pollution by changing how water moves across the landscape: slowing it down, spreading it out, and offering it an opportunity to soak into the ground. Rain gardens, plants and vegetation, and the use of pavers or gravel instead of regular asphalt can help encourage water to soak into the ground more slowly where it can be absorbed and even filtered and cleaned. 

Just remember, nothing but rain should go down the drain!


  • Impervious surface – areas that prevent or impede the infiltration of stormwater into the soil. These are hard, and often man-made surfaces like roads, rooftops, parking lots, and driveways.
  • Infiltration – the process by which water on the ground surface enters the soil
  • Pervious surface – a surface that allows the percolation of water into the underlying soil, also known as porous or permeable surfaces
  • Runoff – the draining away of water (and pollutants carried in it) from the surface of the land, a building, structure, road, etc.
  • Storm drain – a drain that carries water (such as rainwater) away from a street, parking lot, or other impervious surface
  • Stormwater – water that originates from rain, including snow and ice melt. Stormwater can soak into the soil, be stored on the land surface in ponds and puddles, evaporate, or contribute to surface runoff.
  • Watershed – an area of land that drains all the streams and rainfall to a common outlet (e.g. the river). Watersheds can be as small as a footprint or large enough to encompass all the land that drains water into the tributaries of the Columbia and eventually the Pacific Ocean. The word watershed is synonymous with a drainage basin or catchment area.

Link to all Pollution Prevention Vocabulary Terms


Stormwater Activities

Explore hands-on and thought-provoking activities

This project has been funded wholly or in part by the United States Environmental Protection Agency under assistance agreement RB 01J73501 to Columbia Riverkeeper. The contents of this website subpage do not necessarily reflect the views and policies of the Environmental Protection Agency, nor does the EPA endorse trade names or recommend the use of commercial products mentioned in this document.