Press Release: 3/5/2026

How MassDEP's Poposed Noise Policy Update Could Affect Renewable Energy Developers

 



MARCH 04, 2026 BY ADAM P. KAHN ,  ZACHARY GERSON ,  AARON LANG ,  KEVIN Y. CHEN





The Massachusetts Department of Environmental Protection (MassDEP) is poised to revise its Noise Policy for the first time since the Policy’s adoption in 1990. The Policy often plays a critical role in the assessment of operational noise in the Commonwealth, including in siting and permitting renewable energy projects.



MassDEP is revising the Policy based on:




  • MassDEP’s own experience in administering the Policy over the past few decades; 

  • Input MassDEP has received from developers and noise professionals regarding more effective ways to regulate noise;

  • Requests from local health officials for greater clarity; and 

  • An explicit recommendation by the Clean Energy Infrastructure Siting and Permitting Commission that the Policy be updated “to address the disparity of treatment of projects proposed in rural versus urban areas.” 



The Commission’s recommendation was one of several in its March 29, 2024 report to the Governor. Its report served as the precursor to several siting and permitting reforms that were recently codified in “An Act Promoting a Clean Energy Grid, Advancing Equity and Protecting Ratepayers,” Acts of 2024, Ch. 239. For more on those reforms, see our other publications below.



MassDEP’s Discussion Document, which it released on March 2, 2026, outlines several planned revisions to the Policy. Many of them appear likely to improve certainty for project developers, particularly those siting and permitting projects in quieter, non-urban areas, though stakeholder feedback will be critical to ensuring that any revisions are workable. MassDEP is soliciting stakeholder comments on the Discussion Document, which are due March 23, 2026 at 5:00 p.m.



The Current Noise Policy

MassDEP’s 1990 Noise Policy has long guided the agency’s interpretation of its noise regulations. The Policy  has also played a role in other agencies’ environmental permitting proceedings for energy projects, including proceedings before the Energy Facilities Siting Board.



The current 1990 Noise Policy consists of just one page and two requirements:




  1. A sound source may be found to violate MassDEP’s noise regulations (310 CMR 7.10) if it increases broadband sound levels by more than 10 dBA above ambient.

  2. A sound source may also be found to violate MassDEP noise regulations if it produces a “pure tone” condition (i.e., when any octave band center frequency sound pressure level exceeds the two adjacent center frequency sound pressure levels by 3 decibels or more).



Both the 10 dBA limit and the pure tone prohibition are currently measured at the facility’s property line and the “nearest inhabited residence.”



For purposes of the 10 dBA limit, the Policy defines ambient sound as the “background A-weighted sound level that is exceeded 90% of the time measured during equipment operating hours.” This is referred to as the “L90” levels by regulators and acoustics professionals. 



Key Proposed Changes

MassDEP proposed the following key changes to its Noise Policy:




  1. 40 dBA Floor for Quiet Areas. Perhaps the most significant proposal, particularly for developers building projects in quieter areas, is the potential introduction of a 40 dBA baseline below which the “10 dBA above ambient” criterion would not apply. MassDEP notes that this change would be more relevant for projects in areas that are already “extremely quiet,” where allowing sound levels to reach 40 dBA (i.e. comparable to a typical library) may be appropriate even upon an increase by more than 10 dBA. 

  2. Measurement at Sensitive Receptors, Not Property Lines. MassDEP proposes to clarify that compliance should be evaluated at the location of affected receptors rather than at property lines. This clarification would align with the noise regulations’ purpose to protect people adversely affected by noise (as opposed to setting sound limits in locations where few, if anyone, may be directly affected).

  3. Deference to Permit Conditions. Where a project has been permitted by MassDEP, the Energy Facilities Siting Board (EFSB), or local officials under approvals that include specific noise requirements, MassDEP is proposing to evaluate compliance primarily based on the requirements and conditions in those permits. This proposal could benefit from further clarification. Oftentimes, other state agencies and municipalities look to MassDEP’s Noise Policy as a yardstick for assessing noise impacts. In proposing this revision, MassDEP appears to be more expressly allowing regulators to deviate from Noise Policy requirements in their own permits or other approvals.

  4. Revised Approach to Background Sound Studies. MassDEP is proposing to move from using the single lowest 1-hour L90 sound level over seven days of monitoring in favor of the average of the lowest hourly L90 sound levels measured during each daytime and nighttime period. This change would generally result in a somewhat higher ambient baseline when assessing whether a project exceeds that baseline by more than 10 dBA.

  5. Updated Tonal Sound Evaluation Guidance. The agency also plans to update the Policy regarding pure tones to reflect current acoustical best practices, specifically referencing “1/3 octave band analysis under ANSI S12.9-2005/Part 4 Annex C or other generally accepted industry standard (including full octave band where appropriate).”



Implications for Renewable Energy Developers

Taken together, these proposals represent a positive update to the way state regulators address noise compliance. Stakeholders should consider participating in the comment process. MassDEP would benefit from comments regarding the specific experiences of renewable energy developers and others who have worked directly with the 1990 Noise Policy and may be well positioned to recommend updates.



Comments must be submitted to MassDEP by March 23, 2026 at 5:00 p.m.