Stormwater Runoff Race

Human-developed environments often negatively affect the cleanliness and health of a river. Paved surfaces like streets, parking lots and driveways, for instance, create a surface for water to run off too quickly increasing flood risks and also washing down harmful chemicals and other human waste.

There are many other human alterations to the environment that can severely damage our river ecosystems.

Runoff Race

Water currents carry oil spills, sewage, pesticides and factory waste far beyond where they begin. Explore how currents spread all kinds of pollution in the ocean.

Materials needed

• Clear shallow container about 1 1/2" to 2" deep

• Water

• 2 rocks (or upside down coffee cups)

• Measuring cup for pouring water

• Food coloring (yellow, green, red, blue)

• One large ice cube or several small ice cubes

• Part 2

• Cotton ball, paper towel, cotton swabs, sponge, spoon

Procedure, Part 1

1. Fill the container with water 1" deep.

2. Place the rocks or cups in the water (not touching each other). They represent the continents in your experimental "ocean".

3. Add ice cubes to the water.

4. Add drops of food coloring to represent pollution in the water:

• Yellow, 8 drops

• Green, 4 drops

• Red, 4 drops

• Blue, 4 drops

Observe the movement of the food coloring as the ice melts. Be careful not to jostle the container of water! How does the melting ice affect the movement of the food coloring?

Which part of your ocean ended up with the least pollution? Which part ended up with the most pollution? Which spread the farthest? How did the continents affect the currents and spread of pollution?

Procedure, Part 2

Use the cotton ball, paper towel, cotton swabs, sponge, and/or spoon to remove the "pollutant" from the water. Can you clean the water?

What is Runoff?

Runoff can be described as the part of the water cycle that flows over land as surface water instead of being absorbed into groundwater or evaporating. Runoff causes erosion, and also carries chemicals and substances on the ground surface along to the rivers where the water ends up.

What does the food coloring represent?

The food coloring represents Nonpoint Source Pollution. Nonpoint Source Pollution is pollution resulting from many different sources, in direct contrast to Point Source Pollution which results from a single source. Nonpoint Source Pollution is also known as people pollution. It is the result of the actions of many people.

• Excess fertilizers, herbicides and insecticides from agricultural lands and residential areas

• Oil, grease and toxic chemicals from urban runoff and energy production

• Sediment from improperly managed construction sites, crop and forest lands, and eroding streambanks

• Salt from irrigation practices and acid drainage from abandoned mines

• Bacteria and nutrients from livestock, pet wastes and faulty septic systems

• Atmospheric deposition and hydromodification

Since waterways are connected the actions in our watershed can affect all watersheds connected to it. What happens upstream happens downstream.