Stormwater Management

What is Stormwater?

Stormwater is excess rain that does not soak into the ground.  You can see it in the gutter of the street during a rainstorm.  In densely developed areas, like Watertown, stormwater is typically collected in catch basins and manholes and then piped downstream to the Charles River.

Unlike some other nearby communities, Watertown has separate sewer No Dumping Sign and stormwater drainage systems. The drainpipes do not go to Deer Island to be treated like sewage from your house is. Instead, stormwater drainage is collected through catch basins, conveyed through drainage pipes, and then discharged into the Charles River, all with little to no treatment.

As stormwater flows through our yards and streets on the way to the river, it can collect pollutants that harm human health and our fragile ecosystems.  Examples of pollutants that stormwater can transport include fertilizers containing harmful nutrients, oil, grease, viruses, bacteria, toxic metals, sediment, and salts.

Learn more about the Charles River and some of our challenges at the EPA webpage.

View the Watertown "Rain Drain Pain" Flyer (PDF).

Watch this video: Low-impact Development and Stormwater Pollution. 

City Stormwater Infrastructure

What is a Catch Basin?

There are over 3,200 catch basins in Watertown!

A catch basin, which is also known as a storm drain inlet or curb inlet, is a structure with an opening into the storm drain system. They include a grate or curb inlet at street level where stormwater enters the catch basin. But not just stormwater can enter the inlet. Oil and grease, car washing, pet waste, and any number of things can enter through the grate.

Catch basins do provide some pollution protection by preventing trash and other floatable materials from entering the drainage system. Most also contain sumps that allow larger sediments to settle in the basin. Nevertheless, catch basins provide little stormwater treatment.

Cleaning collected debris from a catch basin, part of annual stormwater maintenance performed by DPW contractor.

Street Sweeping

Street sweeping does more than make our streets look nice, it removes trash and sediment from our roads before it can get into our drainage system.

Drainage Pipes

There are over 55 miles of drainage pipe in Watertown, ranging in size from 6 inches in diameter to over 6 feet! These pipes convey stormwater from our catch basins to our stormwater outfalls.

What is an Outfall?

There are over 30 stormwater outfalls to the Charles River in Watertown. These outfalls discharge stormwater directly into the river.

Here is one outfall. It is located right along the Charles River Walk Way between the Charles River and Pleasant Street. All of the Town’s outfalls are labelled; this one is Outfall Number 5, behind 304 Pleasant Street.

View our Drainage Outfall Map (PDF) to find out what outfall you drain to.

What is a Green Infrastructure?

Green infrastructure is an approach to managing stormwater that relies on water’s natural tendency to be absorbed back into the ground. Instead of flowing through downspouts, pipes, and other engineered systems into our catch basins and directly to our outfalls, green infrastructure uses vegetation, soils, and other natural elements to reduce the amount of stormwater and stormwater pollutants.

Links with more information:

Charles River Watershed Association 

Mystic River Watershed Association

Think Blue Massachusetts

Beacon Park bioretention basin during a rain storm