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.

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