Citywide Drainage and Water Quality Master Plan

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The City is developing a Citywide Drainage and Water Quality Master Plan, a collection of infrastructure projects that will reduce flooding, improve water quality, and mitigate combined sewer overflows. After years of modeling and evaluation, the Engineering Division and its consultants have developed 30 projects that would address the root causes of flooding and prepare Somerville for climate change. Now, the City is ready to present these ideas and get feedback from the public. Community input will help identify preferred alternatives and determine which of those 30 projects are included in the final Drainage and Water Quality Master Plan.

The City is developing a Citywide Drainage and Water Quality Master Plan, a collection of infrastructure projects that will reduce flooding, improve water quality, and mitigate combined sewer overflows. After years of modeling and evaluation, the Engineering Division and its consultants have developed 30 projects that would address the root causes of flooding and prepare Somerville for climate change. Now, the City is ready to present these ideas and get feedback from the public. Community input will help identify preferred alternatives and determine which of those 30 projects are included in the final Drainage and Water Quality Master Plan.

  • Green Stormwater Infrastructure Info

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    In 2018 and 2019 leveraging funding from a Municipal Vulnerability Grant, the City of Somerville investigated the potential for Green Stormwater Infrastructure (GSI) to provide flood relief and water quality benefits. The study investigated eight representative neighborhoods to determine the extents to which GSI could be implemented, and utilized our advanced hydraulic model to determine their benefits for a range of storm events.

    This report provides the details on GSI types and logistics for locating them in our Rights-of-Way:


    This report and its appendices provide the conclusion of the benefits evaluation for implementing GSI both in the Rights-of-Way and on private property:


    The report provides important details, but in general, the volume of flood relief provided by GSI varies by location throughout the City, but that volume is substantially smaller than the flood volumes produced by large storms. However, GSI does provide significant water quality benefits, particularly with respect to phosphorus, which is the primary pollutant of concern when considering sewer separation and new stormwater outfalls. Therefore, the solution to flooding will require a combination of “green” and “grey” infrastructure solutions. Those conclusions were carried forward to the Citywide Drainage and Water Quality Master Plan.

    Additionally, the 2018 effort produced planning guidance for both City projects and to provide developers obtaining building permits on how to design GSI. That guidance can be found here:

Page last updated: 12 Apr 2022, 08:21 AM