A watershed is the land near rivers and streams that “sheds water.” This water sheds into nearby water bodies—in this case the North and South Rivers. The watershed is also a critical ecological system, supporting all the life in that area.

Water that falls on the land (like rain and snow) drains downhill. So hills, ridges and other high points define the boundaries of a watershed. Water flows both over the surface of the land and underground (the aquifer), and converges into streams and rivers. The network of streams and rivers converge and grows larger, eventually reaching the ocean.

Watersheds can be large or small. Every stream, tributary, or river has an associated watershed, and small watersheds join to become larger watersheds.

Watersheds can also be called basins and drainages. Here’s what a watershed looks like:

Where are the North and South Rivers located and how large is their watershed?

The North and South Rivers watershed covers 12 towns on the South Shore: Norwell, Hingham, Scituate, Marshfield, Hanover, Pembroke, Whitman, Hanson, Duxbury, Weymouth, Rockland and Abington.

The North River rises from marshes and springs in Weymouth, Rockland and Hanson, and flows through five towns, draining approximately 59,000 acres before it empties into the Atlantic Ocean. The North River is approximately 12 miles long, running through Hanover, Pembroke, Marshfield, Norwell and Scituate. There are approximately 3,300 acres of marshes along the North River and just under 2,000 acres of endangered species habitat. Some major North River tributaries include the First Herring Brook (Scituate), Second Herring Brook (Norwell), and Third Herring Brooks (Norwell and Hanover) and the Herring River (Scituate).

The source of the South River lies in Duxbury at Round Pond. The river is approximately 15 miles long and runs through Duxbury, Marshfield and Scituate. Tributaries to the South River include the Furnace Brook (Marshfield) and Phillips Brook (Duxbury).

Both rivers share the same outlet to the Atlantic Ocean, between Third and Fourth Cliffs in Scituate.

How many people live in the watershed?

The North and South Rivers Watershed is home to approximately 150,000 people. Which is the only town that lies completely within the watershed? Hanover.

Who relies on the watershed for drinking water?

Approximately 80% of Scituate’s water supply (pop. 18,133) is from the First Herring Brook watershed, a tributary of the North River.  Norwell (pop. 10,506) obtains some of its water from the Third Herring Brook watershed in Norwell and Hanover and some from the Weir River watershed in Hingham. Hanover (pop. 13,879) uses water from the watersheds of the Third Herring Brook and Iron Mine Brook (a tributary to the Indian Head River). Pembroke (pop. 17,837) uses water from wells within the Herring Brook watershed. Marshfield (pop. 25,132) relies on drinking water from the Furnace Brook watershed (a tributary to the South River).

How do people use the watershed?

Many people on the South Shore rely on the watershed for clean drinking water. However, the rivers, streams, lakes and ponds are also great for recreation, like canoeing and kayaking, boating, swimming and fishing. The watershed lands are perfect for nature walks and hikes, on- and off-road biking, cross-country skiing, snow shoeing, birding, hunting and shellfishing.

How do human activities affect our watershed?

Without our even knowing it, many of our daily activities can pollute the watershed and reduce the amount of fresh water for everyone. During rainstorms, pollutants wash into the rivers–including salt and oil from roadways and parking lots, sand and debris from construction sites and chemicals from our lawns.

When we clear land, we not only expose watershed soil to erosion, but also cause changes to the water cycle, affecting flows in the rivers. When land is paved or covered with buildings or other impervious or hard surfaces, the ground cannot absorb water from rain or snow. Instead, the water flows over the ground as runoff. This situation can result in higher peak flows during storm events. At the same time, less water can be stored in the ground. This groundwater is what provides continuous flow in a river, even when it’s not raining. So, decreasing groundwater results in less flow in the river during low-flow periods.

Other human activities that affect the North and South Rivers and its tributaries are water withdrawals for human use and the loss of water via sewer pipes.

Historical activities that today still impact our watershed include road crossings that are not wide enough to allow the rivers to flow freely and dams built to power first the colonists saw mills and grist mills and then the industrial revolution. These dams largely remain today though the purposes that they were built for are long gone.  These aging pieces of infrastructure fragment our rivers having detrimental impacts on the ecology of our rivers and in particular native fish like river herring, shad and brook trout whose populations have been heavily impacted by these dams and other human activities.