The Watershed Model

This activity uses a large watershed model to demonstrate the negative effects of stormwater runoff and human pollution.  Participants will find out what a watershed is and how events on land impact the water.  They will also explore how green projects can prevent stormwater from entering our creeks and rivers.

The model promotes awareness about healthy watersheds by helping participants recognize how their actions affect the Bay, and what they can do to make a positive impact.  It may be paired with lessons about the water cycle and the importance of wetlands; it’s also a great way to introduce topics like sustainable agriculture and pollution-reducing “habits that help.”

This resource works best as an activity or station for a small group (15 people max), so everyone can comfortably fit around the model and participate in the demonstration.  While it works great for after-school clubs or classroom presentations, it is not as well suited for an audience with limited time, and requires careful preparation to be used effectively at tabling events.

To adapt this resource for different groups and audiences, see our suggestions for Adaptations below.

A quick guide to using the Watershed Model

* Prior to starting, set up the model and have all the supplies ready.

Concepts to Explore:

A watershed is an area where all the rivers and streams drain to a common area.  Everyone in Maryland lives in the Chesapeake Bay Watershed, which is home to 18 million people, covers 64,000 square miles, and stretches across 6 states and the District of Columbia.

• The ratio of land to water in the Chesapeake Bay watershed is 14:1. What happens on the land affects the water.

• Over several hundred years, the vast wetlands and forests that absorbed water from rainstorms and filtered/cleaned it before it entered the Bay, have been replaced by farms, cities, and roads.

• The difference between pervious/impervious surfaces, point/nonpoint source pollution.

• Without green areas that filter rainwater and help it slowly sink into the ground, stormwater picks up chemicals and carries pollution into the Bay.  Restoring the land by adding projects with native plants and trees can reverse the negative cycle created by human development.

• Some of the problems in the Bay may be fixed if we make simple changes to our behavior.

Move and Learn: Teach the “Watershed Dance.” (See supplement for instructions.)

Hands-On-Activity: Use the model to guide your participants through a story about what happens to a pristine watershed when human development takes away the natural green filters.  Have them help you add structural elements to the model, and then spray it with water to see what happens.

Optional Outdoor Activity: Walk around the area and observe anything contributing to runoff.  What can be done to prevent pollution reaching the stream or Bay?

Reflection: Don’t forget to ask your participants what they learned and how they can use their knowledge to take action for a healthy watershed.

Materials

• The Watershed Model, including buildings, farm animals, vehicles, and trees

• Sponges

• Spray bottles to hold water for “rain”

• Squeeze bottles and powdered drink mix or food coloring to represent pollutants like fertilizer, pesticide, and oil

• Small shakers filled with cocoa or coffee grounds to represent sediment and pet waste

• Small shaker with colored sprinkles to represent microplastics

• Optional: Map of the Chesapeake Bay Watershed and copy of The Watershed Dance

• Optional: Map of the local watershed where your program is taking place

• Optional: A River Ran Wild: An Environmental History by Lynne Cherry.  Copies available through Marina; a 9-minute read-aloud version is available here.

* Stewards may borrow WSA's Watershed Model for educational programs and events.

Directions

Before your group arrives, set up the watershed model in its “pristine” state with sponges, and trees.

1. Movement and Exploration  

• What is a watershed? Define it and introduce the Watershed Dance. 

• Show a map of the Chesapeake Bay watershed.  Locate where you are on the map. Name the closest river to where you are. You are (probably) in that watershed which in turn is part of the Chesapeake Bay watershed.  Name the states and district that comprise the watershed (Virginia, West Virginia, Maryland, Pennsylvania, Delaware, New York, and the District of Columbia).

• The Chesapeake Bay watershed is 64,000 square miles; more than 18 million people live here; and it is about 500 miles from its northernmost point in New York State to the mouth of the Chesapeake.

• This model demonstrates what a watershed is and how runoff from land affects the water.  There are other factors that affect water quality not shown in this model, specifically how pollution from the air gets washed into the rivers when it rains, and the effect of oysters on the Bay.

2. Further Exploration (optional): Read A River Ran Wild by Lynne Cherry. Cherry’s story is about a river in New Hampshire, but there are nice connections that can be made to what has happened to the Chesapeake Bay.  YouTube read aloud here.

3. Hands-on-Activity

• Ask your audience to travel back in time a hundred years with you.  Tell a story about the watershed, by pointing out the forests and the sponges representing wetlands.  Demonstrate rain by squirting the spray bottle over the area.  You may give a participant the bottle to do this or give a few participants one squirt each and then pass it to the next person.  Observe the clarity of the water as it flows into streams and eventually into the Bay.  Any decaying matter or poop from woodland animals would be absorbed by the wetlands.

• You may act out the story below by passing out materials and adding to or subtracting from the watershed model as the story progresses. 

  • • The first European settlers arrived by boat.  (A boat can sail into the bay.)

    • What would they need in order to survive? (Food, Water, Shelter.)

    • What would be the first thing they would build?  Farm (Clear some trees and sprinkle with cocoa to represent bare dirt. Add farm animals.)

    • Farmers liked this place and wrote back to their friends and family.  More people moved in.  (Clear more land and wetlands and place houses on model.)

    • More people means a need for more food. (Add more “fertilizer” to farm area.)

    • Livestock is not toilet trained. (“Fertilizer” can be used as poop.)

    • What would then be built?  Roads, bridges.  Chainsaws would have to take down trees, bulldozers remove wetlands to build bridges. (Add and subtract items as story is told.)

    • More houses are built.  Bulldozer can go on home construction site. Owners want pretty lawns and use fertilizer. (Remove wetland sponges. Sprinkle drink powder.)

    • Cars are on the roads. (Add drops of syrup on roads.)

    • Need a place to work – Factory (Add drops of food coloring to stream.)

    • Children need a place to go to school. (Clear more land.)

    • Need a place to play – Green felt to represent a playground. (optional)

    • Snowstorms blanket roads and salt is added. (Sprinkle powdered milk on roads.)

    • Now the watershed model is built up as it basically is today.

    • Now let it rain and discuss the differences in the runoff.

• List the actions that caused pollution in the Bay.  What can be done to improve the water? (Plant more trees; restore wetlands, fence livestock away from streams; properly maintain cars; use less fertilizer; enforce clean water regulations on factories and businesses.)

4. Continued Exploration Outside (optional): Go for a walk outside. Notice anything in the landscape that might be creating runoff for the Bay.  What can be done in this community to prevent runoff carrying pollution and soil from reaching the Bay?

5. Reflection: Get the audience thinking about what they've learned and how they can take action.

• What are some actions that contributed to the pollution of the Bay? 

• Where in your community is there bare ground and how does it affect the Bay?

• What effect would planting along the sides of a stream have on the Bay?

Now that the Bay is in this condition, what can be done to ameliorate the situation?

• Replant along shoreline.

• Use permeable surfaces when possible.

• Cover bare ground.

• Dispose of toxins properly and reduce their use when possible.

Suggested Reflection Prompts for Different Age Groups

• Grades K-2: Where does all the water eventually go no matter where it fell? What happens to the water along the way?  In what direction does water flow?  If something is upstream, where will it go?

• Grades 3-5: How does someone upriver affect the people downriver? Where do you think runoff around here picks up pollutants? We can’t change how we got here, but how can we change for the future?  How can we get more runoff to soak in?  If people create bear ground by cutting across the grass instead of staying on the sidewalk, then what happens to that dirt when it rains?  What would keep it from eroding?

• Middle and High School: What are practices farmers and construction sites can perform to improve the Bay? How do wetlands, trees, and other plantings help the Bay?  What can you do to help prevent erosion?  What are some activities you could get involved in to help our watershed?

• Bonus High School/Adults: Some watersheds drain to the ocean, others drain to the Great Lakes. The watersheds of the Great Lakes Basin include land in the United States and Canada. What kind of challenges do you think might arise when a watershed is located in two different countries? What kind of cooperation might be needed to ensure the health of that watershed, and how do you think this is similar to or different from what happens in the Chesapeake Bay Watershed?

• Mixed Age / Families: What are things we/families do that adversely affect the Bay?  What is an action we can take to make things better? We recommend drawing questions from our K-5 examples so that everyone will be able to participate.

Sample Lesson Plan 

Click the link for a sample lesson plan by Watershed Steward Nan Henry.

We believe the Watershed Model can work with audiences of all ages in a variety of settings.  It’s also possible to do a fun, engaging presentation about watersheds without using WSA’s model at all!

General Suggestions

You can do fun hands-on activities about watersheds without using the watershed model, by creating your own using simple materials you have at home!  Check out our companion lesson, All About Watersheds.

Adaptations for Different Audiences

The Watershed Model works well for any age.  You may adapt the story as needed, and it can easily be adapted for the specific audience you’ll be engaging.  For example, instead of a school, a new building in town could be a nursing home or a library; trees may have been cut down to make room for cell towers or a playground.

Adaptations for Different Formats

• Presentation for a Large Audience (more than 20, not as interactive or hands on):  If audience is too large to gather around the model and participate, consider using this as a station with other activities.  Or the group could be split in half, with someone discussing the map and reading the book, and someone else running the model and reflection.

• Program with a Club: the model could be part of a series of lessons about the water cycle, dead zones, and erosion.

• Table at a Community Event or Festival: If the audience is passing by and not staying for a whole presentation, have the model set up with modern additions (buildings, roads) in place.  Demonstrate the effects of runoff and pollution; then, ask your audience to add green areas (sponges) on the model, and see what happens when it rains!

Key Terms

Watershed – an area where all the rivers and stream drain to a common area.

Runoff – water that flows downhill to a stream or other body of water.

Pervious – a material that allows water to pass through it.

Impervious – a material that does not allow water to pass through it.

Point Source Pollution – pollution that comes from a source we can easily identify, including pipes, sewers, channels, and ditches.

Nonpoint Source Pollution – pollution that does not come from one specific location; instead, it is runoff that collects and deposits pollution over a wide area.

Fun Facts

• The Bay holds about 18 trillion gallons of water. That amount of water would fill more than fifty billion bathtubs to the brim.

• Only about half of the water in the Bay comes from the ocean. The rest comes from the 64,000 square mile watershed, which extends approximately 524 miles from Cooperstown, New York to Norfolk, Virginia.

• Roughly 51 billion gallons of water enter the Bay each day from the 100,000 streams, creeks, and rivers that feed it.

• Every year, new parking lots, driveways, roofs, and other hardened surfaces from development convert land in the Chesapeake Bay region from great green filters to hard grey funnels. Every four years, an area of land the size of Washington, D.C. is lost.

• The Bay's fishing industry used to harvest tens of millions of bushels of oysters. Today, harvests have fallen to less than one percent of historic levels.

More Information

From The Changing Chesapeake: an introduction to the natural history and cultural history of the Chesapeake Bay by Valerie Chase

A good description of how water reaches the Bay:

Two things may happen to the rain and snow that falls on the Chesapeake Bay watershed, the land that drains into the Bay.  Some of the water runs over the land directly into streams and rivers and is called runoff.  The rest of the water soaks into the soil and moves down through soil and rock until it reaches the groundwaters where the spaces in the rock layers are full of water.  When the groundwater meets the surface of the earth, the water runs out as springs which also flow into screams and eventually into the Bay.  People tap into the groundwater when they dig a well.

From The Chesapeake Bay Foundation, “Polluted Stormwater Runoff: A Growing Threat"

The causes and effects of runoff:

Runoff pollution is increasing because the amount of land covered by parking lots, roads, roofs, and driveways, continues to grow. Meanwhile, forests, meadows, and other natural filters are disappearing, and manmade filtration systems to control runoff have not compensated for the loss.

With climate change potentially increasing the amount of precipitation, localized flooding can result as once designated "100-year storms" occur with greater frequency.

Only 10 to 20 percent of rain that falls in forests, fields, and other natural areas runs off, with the rest absorbed by soil and plants. By contrast, close to 100 percent of the rain that falls on concrete and other hard surface produces runoff. An inch of rain falling on an acre of hardened surface produces 27,000 gallons of runoff.

Further Reading

The Chesapeake Bay Foundation - The Chesapeake Bay Watershed 

The Chesapeake Bay Program – Modeling and the Chesapeake Bay

Caring for Our Watersheds – Watershed Information: Chesapeake Bay Watershed

USGS EarthWord - Watershed

The Watershed Model - all the information on this website in one PDF

The Watershed Model Quick Guide - a PDF version you can print