BUILDING RESILIENCE IN THE WATERSHED
Protecting and Expanding our Tree Canopy
Climate Change Is Here
Massachusetts has warmed by approximately 3.5 degrees Fahrenheit since the beginning of the 20th century. As our climate continues to warm, we expect more frequent and intense heatwaves will impact the watershed, putting vulnerable populations at risk and straining community resources. Extreme heat is the most common cause of weather-related deaths globally.
Warming temperatures also impact the native biodiversity of plants and animals in our watershed. Increasing temperatures can cause a decline in forest health and the loss of carbon sequestration and other ecosystem services.
BY 2070, OUR REGION IS EXPECTED TO EXPERIENCE
Up to 50 days a year where temps exceed 90 °F
Changes in seasonal and growing patterns
Loss for ecosystem services, possibly with severe consequences
Over 180 days annually without rain
Working Together for Regional Solutions
Founded in 2019, the Charles River Climate Compact (CRCC) is a collaboration of over two dozen cities and towns. Led by CRWA, the CRCC takes a regional approach to climate adaptation to address flooding, sea level rise, extreme heat, and river health.
In 2023, CRWA and CRCC were awarded a grant to develop a Regional Tree Protection and Planting Plan for the Charles River watershed. Funding for this project was provided by the USDA Forest Service.
Do you see your city or town? Participating communities include Arlington, Bellingham, Belmont, Boston, Brookline, Cambridge, Dedham, Dover, Franklin, Holliston, Hopkinton, Lincoln, Medfield, Medway, Millis, Natick, Needham, Newton, Norfolk, Sherborn, Somerville, Walpole, Waltham, Watertown, Wellesley, Weston, Westwood, and Wrentham.
Trees Are a Climate Solution
Trees provide cooler neighborhoods, cleaner air, flood reduction, cleaner water, and mental health benefits. Yet our watershed is losing tree canopy at an alarming rate (average 6.9% by municipality across the watershed from 2008 to 2021).
Social inequities also result in variable tree cover across the watershed area. In the Charles River watershed, areas with high percentages of low-income or minority residents typically have less tree canopy cover and are, therefore, more at risk from the impacts of extreme heat. By taking a regional approach, we can work to address tree loss and inequities.
(Left) Map of tree canopy cover by block groups within the watershed meeting the Mass EEA criteria requirements for EJ and how many criteria they meet.
Our 2024 existing conditions tree canopy assessment of the watershed showed that:
Check out our StoryMap to learn more about the state of the existing tree canopy in our watershed.
Watershed municipalities have lost an average of 6.9% canopy across the watershed from 2008 to 2021, with the majority of that loss occurring between 2012 and 2017
Tree canopy is not evenly distributed across the watershed, with most canopy concentrated in the upper and middle watershed
Environmental Justice (EJ) areas have lower average tree canopy cover (ranging from 13 to 38%) than communities with no EJ block groups (61%)
Most significant losses across subregions occurred on private lands*
41% of the watershed canopy is protected by some form of policy or protection strategy
73% of tree canopy is on private land, and 25% is on public land
*Or areas where ownership was not easily classified
If tree loss trends continue, the watershed may lose up to 54,000 acres of unprotected forest by 2060
10 of 35 watershed municipalities have a tree ordinance/bylaw
In 2025, the Charles River Climate Compact (CRCC) developed the Regional Tree Protection and Planting Plan to provide a central resource to help municipalities and residents maximize the health and benefits of existing trees, help protect trees from invasive species and other threats, and identify new opportunities for tree planting to ensure a robust, healthy tree population that can thrive in our changing climate.
The plan recommendations are organized in three categories: Protection, Planting & Expansion, and Maintenance of trees to encompass a holistic overview of tree management for increasing climate resilience benefits.
Recommendations in this Plan are not isolated from one another, but rather a compilation of actions that can be implemented in various aspects of watershed communities’ regulations, culture, and management practices.
LEARN MORE
Watch our latest public webinar recording on this initiative in on our our playlist.
Have questions or want a presentation for your community?
Contact Dira Johanif, Senior Climate Resilience Manager at djohanif@crwa.org