Introduction

A 2025 draft of The Massachusetts Guide to Lake Management (MassGLM) has been released for the public and regulatory agency review and comment.  This version of the MassGLM is intended to provide an update to the 2004 Generic Environmental Impact Report on Eutrophication and Aquatic Plant Management in Massachusetts and the accompanying Practical Guide to Lake Management in Massachusetts.  The original Generic Environmental Impact Report for Eutrophication and Aquatic Plant Management in Massachusetts (GEIR) was developed in the late 1990s and early 2000s.  Over the last two decades, much experience has been gained with the management of lakes and ponds.  Additionally, changes in regulations have created additional needs not addressed in 2004 and this document incorporates this information.  This 2025 guide incorporates updates to both the GEIR and Practical Guide into one hybrid document titled "The Massachusetts Guide to Lake Management (MassGLM)".​

The purpose of The MassGLM is:

1. To provide guidance to lake and pond managers, conservation commissions, and citizens concerned with lake management issues.
2. To provide a basis for more consistent and effective lake management in the Commonwealth.
3. Describes technical approaches and management options for control of algae and aquatic vegetation and protection of lakes.

Key updates in The MassGLM includes:

1. It is designed as an editable online resource for internet access. 
2. Hyperlinks throughout the document take you to various websites with additional information.
3. Emphasis is placed on the importance of a sound and comprehensive lake management plan and how to develop one. 
4. Updated science related to lake ecology.
5. Greater focus on the management of algae and aquatic vascular plants. 
6. Acknowledgment that separate guidance must be sought for other ancillary issues, such as fishery management, dam safety, or flood control.  
7. A consolidation of regulatory requirements into one chapter.  
8. Clarification and distinction of those lake management techniques deemed acceptable for use in Massachusetts versus alternative techniques either not accepted, rarely applied, or without a sufficient track record to allow proper evaluation. Many of those alternative techniques may be applicable and even appropriate but require additional scrutiny. 
9. Experience with phosphorus inactivation has expanded greatly, facilitating wider application and more guidance for best results.  
10. Circulation and oxygenation techniques have been separated and expanded, based on considerable advancements in that field over the last two decades. 
11. Coverage of active ingredients in algaecides and herbicides registered for use in Massachusetts as of 2024 has been added; herbicides and algaecides are addressed in a single section. 
12. Changes in the guidance for how drawdowns should be conducted without MEPA review, but an appendix is also provided for considerations for projects where a MEPA review may be necessary. 

Next Steps for The MassGLM:

1. DCR is working with partners to rollout the guide to the public.
2. Public comment will be accepted until May 15, 2025.