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Everyone in the world lives in a watershed

but what are they?

Think of a watershed like a funnel.  If you place a drop of water anywhere in the funnel, it will fall out through the spout.  A watershed works much the same way, and is the land and drainage area where water runs downhill into a body of water.  Hills, mountains, and sloping topography separate watersheds and act like the walls of the funnel, and the rivers, streams, and stormwater drains represent the spout that concentrates the water flowing over the land, channeling it elsewhere.  

Picture a drop of water falling on a hill, miles from the nearest stream.  When the rain falls, some of the water soaks into the soil and some evaporates into the air.  Everything else runs off the land.  That water joins small streams and wetlands that drain into lakes and rivers, and eventually flows to the ocean.  This is how trash, chemicals or bacteria miles from a water body can still end up in our rivers and lakes, and it's why we all need to understand how our actions impact things downstream!

A change in the watershed affects our lives, and a change that we make in the landscape affects the watershed.  It’s all connected.  Nature’s changes can be as quiet as branches building up behind a fallen log and changing the path of a stream, or they can be as dramatic as a springtime flood.  Our actions, too, can be subtle or very dramatic, but they all affect someone or something.  When we cut forests, clear land, lay concrete, and build houses and towns we cause changes in the watershed. Those changes mean the water cycle works differently.


When rain striking the ground has fewer places to soak in gradually, runoff is faster and more violent, causing erosion and flooding.  Water quality deteriorates as water drains from farms and cities carrying pesticides, animal waste, oil and heavy metals into our groundwater, streams, and eventually, the Great Lakes. 

The more you know about our watershed, the more you can do to protect it.  Which one do you live in?

Watershed diagram-1.png

Learn the Language: Watershed Words


  • Aquifer: An underground water supply flowing through rock.

  • Catchment: Another name for a watershed.

  • Discharge: The volume of water that passes a given location  within a given period of time, often expressed in cubic feet  per second.

  • Drainage Basin: Another name for a watershed.

  • Groundwater: Water that lies beneath the earth’s surface.

  • Headwaters: Source of a stream or creek on the upper reaches of a river.

  • Hydrologic: Related to water in all its forms.

  • Hydrologic Unit Code (HUC): The U.S. is divided and sub-divided into successively smaller hydrologic units which are classified into four levels: regions, subregions, accounting units, and cataloging units. The units are arranged or nested within each other, from the largest geographic area  to the smallest geographic area. Each unit is identified by a unique HUC consisting of two to eight digits based on the four levels of classification. The 8-digit  HUCs are often referred to as watersheds. There are 64  HUCs  within Michigan.

  • Illicit Connection: A physical connection to the separate storm sewer that 1) primarily conveys illicit discharges into the system, or 2) is not authorized or permitted by the local authority.

  • Illicit Discharge: Any discharge to, or seepage into, a separate storm sewer that is not composed entirely of stormwater or uncontaminated groundwater. This can be through pipes or other physical connections including dumping of motor vehicle fluids, household hazardous wastes, domestic animal waste, leaf litter, grass clippings, restaurant waste, etc. 

  • Impervious: A surface that little or no water can filter through, such as roads, parking lots and rooftops. 

  • Infiltration: The slow movement of water from the surface to the groundwater.

  • Non-point Source Pollution: Pollution caused when rain,  snowmelt, or wind carries pollutants off the land and into waterways. 

  • Runoff: Precipitation or irrigation water that does not infiltrate but travels over the land surface and  ends up in water bodies.

  • Stormwater: Includes stormwater runoff (from rain events), snow melt runoff, and surface runoff and drainage.

  • Storm Drain: A slotted opening leading to an underground  pipe or channel that carries stormwater runoff from the land.

  • Watershed: The land from which rain collects and runs to a single point.

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