Stewardship Monday: What is a watershed?

The water that flows through the San Francisco Bay is part of a watershed that covers 40% of California. What is a watershed? A watershed is an area of land over which all water eventually flows to the same point. Starting at the tops of mountains, water flows (usually from melted ice and snow); forming rivers, streams, lakes, groundwater and every other form of water. Everywhere is part of a watershed!

The major watershed that flows eventually through the Sacramento—San Joaquin River Delta and ultimately out through the Golden Gate may cover 40% of California, but it is the primary source of water for 25 million Californians and 7000 square miles of agriculture. This water is not only important for the humans who live here (who use over 50% of the water), it is also shared by many delicate habitats that house a diversity of organisms. Some endangered species such as delta smelt, steelhead, and Chinook salmon rely on the San Francisco Bay Delta watershed to survive.

You can easily make a model of a watershed at home or in the classroom, and experiment with diverting flow, adding or removing barriers and “marshes” (which can be simulated by a sponge) to see what happens. Simply use clay or plaster to create your hand imprint. The ridges represent mountains and hills—spray water over the cast and watch how it flows into the creases and cracks to form rivers, and pools at the lowest point—the ocean! Adding sprinkles of KoolAid or hot chocolate might help to make the streams stand out and demonstrate how water picks up all kinds of stuff as it flows.

Join our students as they discover their own local watershed and learn how we are all connected. Follow their journey on our YouTube channel.

Stewardship challenge of the week: find out the name of your local watershed and try to visit it! You may find yourself at a beautiful creek. You can be a hero to the ocean, and everywhere in between, by picking up trash before it flows all the way to the sea.


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