MassDEP Proposes Changes to Chapter 91 Regulations

Applicants for new/renewed licenses must address climate issues

The Massachusetts Department of Environmental Protection (MassDEP) is proposing regulatory revisions in response to the effects of a changing climate, including sea level rise, increased precipitation, and intensifying storms.

To address these issues, MassDEP recently announced its proposed “resilience” amendments to the Commonwealth’s waterways regulations, 310 CMR 9.00, also known as the Chapter 91 regulations, named after the enabling statute. The amendments are intended to ensure that licensing “properly reflects the potential effects of climate change” for existing and proposed structures along the waterfront.

The Chapter 91 Waterways Regulations govern structures, fill, and uses in jurisdictional tidelands, great ponds and non-tidal rivers and streams in Massachusetts. Generally, such structures, fill, and uses must be licensed or permitted by MassDEP and, in accordance with the Public Trust Doctrine, the public must continue to have access to these areas.

Key proposed changes to the regulations include:

  • New definitions. The regulations will now define key concepts and terms including A Zone (or AE Zone), Land Subject to Coastal Storm Flowage, Moderate Wave Action Area, and Velocity Zone (or V‑Zone) for consistency with the Wetlands Protection Act regulations (310 CMR 10.00). The proposed amendments also remove the definition of Coastal High Hazard Area and use the term Velocity Zone in its place.
  • Changes to height requirements. The height requirement for water-dependent uses would be modified to allow licensees to move utilities from the basement (where flooding is likely to occur) to the roof. Nonstructural elements relocated to the roof of an existing building for a non-water-dependent use may be excluded from the height requirement for purposes of licensing. Solar panels would also be allowed.
  • New standards related to sea level rise. Currently, only non‑water-dependent projects located in flood zones must incorporate projected sea level rise during the design life of a building. MassDEP’s proposal will require consideration of projected sea level rise for all fill and structures, within and outside current flood zones, and for the design life of the fill, structure, or public facilities – not just buildings. MassDEP will require applicants to use sea level rise projections published by the Commonwealth ( or other similarly reliable sources.
  • License/permit renewals must address sea level rise. As proposed in the regulatory amendments, applications for renewal of a license or permit must take into account existing conditions and all applicable regulatory provisions at the time the renewal application is submitted, including the changes associated with the impacts of sea level rise on the fill or structures and any public access or other public benefits. Accordingly, renewals of the so‑called amnesty licenses issued in the 1990s (typically for 30 years) will need to meet the new standards. This is a drastic change in license renewal requirements and will call into question the financeablity of any improvements that will need a license renewal during the term of the loan.

MassDEP will conduct two public information sessions on Wednesday, January 17, 2024 via Zoom: one at 1:00 p.m. and one at 6:00 p.m. Advance registration is required. MassDEP will also conduct public hearings on the proposed amendments on Thursday, January 25, 2024 at 1:00 p.m. and 6:00 p.m. via Zoom. Registration is required.

Written comments on the proposed amendments will be accepted until 5:00 p.m. on March 1, 2024. MassDEP encourages electronic submission by email to and must include Waterways Resilience Comments in the subject line.

Additional information regarding the proposed amendments, including links to register for the public information sessions and hearings, can be found here.

If you have any questions on the proposed amendments or how they may affect your property, or would like assistance drafting public comments, please contact Pierce Atwood environmental and land use attorneys Daniel Bailey, Paula Devereaux, Michelle O’Brien, or Gareth Orsmond.