Fun Facts About the Watershed

What is a watershed?

A watershed is the land which “sheds water,” or drains, into a particular water body—in this case the North and South Rivers. The watershed is also an ecological system based on water, supporting all the life in that area.

Water that falls on the region (as rain, snow, etc.) drains downhill, so hills, ridges and other high points define the boundaries of a watershed. The water flows over the surface of the land and underground (an aquifer) that converge into streams and rivers. As you move downhill and this network of streams and rivers converge and progressively grow 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 is an example of what a watershed looks like:

Photo from the Canada Natural Resources website.

Where are the rivers located and how large are the rivers and their watershed?

The North and South Rivers watershed encompasses 12 towns within its drainage area: 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 seven towns, draining approximately 59,000 acres, before it empties into the Atlantic Ocean.  The source of the South River lies in Duxbury at Round Pond. The rivers share the outlet to the ocean in between Third and Fourth Cliffs in Scituate.

The North River is approximately 12 miles long from the “Crotch” where the Indian Head River and the Herring Brook meet to the mouth and runs through Hanover, Pembroke, Marshfield, Norwell, and Scituate.  There are approximately 3,300 acres of marshes in the North River and just under 2,000 acres of endangered species habitat.  The South River is approximately 15 miles in length from its headwaters and runs through Duxbury, Marshfield and Scituate.

Some major tributaries to the North River include the First Herring Brook (Scituate), Second Herring Brook (Norwell), and Third Herring Brooks (Norwell and Hanover) and the Herring River (Scituate). Tributaries to the South River include the Furnace Brook (Marshfield) and Phillips Brook (Duxbury).

How many people live in the watershed?

The North and South Rivers Watershed is home to approximately 150,000 and includes all or some of the 12 towns noted above. Only the town of Hanover lies completely within the watershed.

Who relies on the watershed for their drinking water?

Approximately 80% of the town of Scituate’s water supply (17,863 pop. as of 2000) is from the First Herring Brook watershed, a tributary to the North River. The town of Norwell (pop. 9,765 as of 2000) obtains some of their water from the Third Herring Brook watershed in Norwell and Hanover and some from the Weir River watershed in Hingham. The town of Hanover (pop. 13,164) uses water withdrawn from the Third Herring Brook watershed and Iron Mine Brook (a tributary to the Indian Head River). The Town of Pembroke (pop. 16,927) uses water from wells within the Herring Brook watershed. The Town of Marshfield (pop. 23,324) relies on drinking water withdrawn within the Furnace Brook watershed (tributary to the South River).

How do people use the watershed?

Many people use the watershed for their drinking water. However, the river, streams, lakes and ponds also provide recreation, including canoeing and kayaking, other boating, swimming and wading, and fishing. The watershed lands provide many other recreational opportunities, including walking and hiking, on- and off-road biking, cross-country skiing and snow shoeing, birding and nature observations, hunting, golf and clamming.

How do human activities affect our rivers?

Activities in the watershed affect the North and South Rivers and their tributaries in several ways. During rainstorms, pollutants wash into the rivers, from roadways and parking lots, construction sites, lawns, landfills and other “non point” sources.

Clearing land not only exposes soil to erosion, but also results in 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 is stored in the ground. This groundwater is what provides continuous flow in a river even when it is not raining. So decreasing groundwater results in less flow in the river during low-flow periods.

Other activities that affect the North and South Rivers and its tributaries are water withdrawals for human use, and the loss of water via sewers. These activities reduce the amount of fresh water available for the river.