Updating the Groundwater Conservation Overlay District
Latest Update
The Boston Zoning Commission approved minor updates to the Groundwater Conservation Overlay District (GCOD) zoning regulations on October 22, 2025. The approved zoning updates include:
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Consolidating and simplifying the existing zoning text to be more legible; and
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Not requiringSubstantial Rehabilitation projects to seek zoning relief from the Zoning Board of Appeal. Note: Substantial Rehabilitation projects still need approval from the The Boston Groundwater Trust (BGwT) and the Boston Water & Sewer Commission (BWSC). If there are other zoning violations for the project, it must still go to the ZBA.
Overview
The GCOD is regulated by Article 32 of the Boston Zoning Code which prevents deterioration, and promotes the restoration of groundwater levels in different parts of Boston. The GCOD is mapped in areas of the City that are on filled land, where many buildings are supported on wooden piles. When the groundwater goes below these wooden piles, they can deteriorate and cause structural and safety issues for the buildings they support.
Applicable development projects within the GCOD must incorporate groundwater recharge systems, which ensure that water infiltrates into the ground instead of onto the streets, and certify that there is no negative impact on groundwater levels from the proposed project. The BGwT and BWSCreview applicable projects for compliance.
2025 Zoning Amendment
The proposed updates for GCOD were made in Article 32, with some minor changes in Articles 2 and 3. TheGCOD Zoning Text Amendment is available below:
A summary of the GCOD Zoning Text Amendment is available here: