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Frequently Asked Questions


A "public shade tree" is a large tree with overhanging branches which provide shade in a public area, such as a sidewalk or park. A small ornamental tree or shrub is not a "shade tree" because it doesn't cast much usable shade.
Public shade trees:
  • Help keep us keep cool walking down the sidewalk or waiting for a bus or just relaxing by the side of the road.
  • Help reduce urban heat islands by shading heat-absorbing pavement.
  • Help control storm water by consuming ground water so permeable surfaces nearby can absorb more water.
  • Help remove carbon dioxide and provide oxygen and cooling water vapor to the atmosphere.
  • Help clean the air by absorbing pollutant gases and filtering particulates through their leaves and bark.
  • Help build community by providing public shady spots for people to relax and chat, particularly with a bench or two underneath.
  • Help connect wildlife corridors for native and migratory pollinators and birds.
  • Help to mitigate global climate change by storing carbon - "think globally, act locally".
The minimum front setback of at least 15 feet comes from the guidance of the Town of Arlington’s Tree Warden. Shade trees need sufficient area to collect water, nutrients and expand as they grow. While small ornamental trees may survive in less space, true shade trees need at least 15 feet. Larger setbacks allow for larger trees, see Arbor Day planting guides. This setback distance provides a pleasant streetscape for pedestrians and a habitat for butterflies, birds and other native species.
Although you can see huge shade trees growing in the unpaved area between the street and the sidewalk, it's not ideal. When trees are planted that close to the road:
  • The roots can be can be severely damaged by heavy equipment going over them in road and sidewalk work, and digging up the street for utility work.
  • Road salt and pollutants from cars can damage trees planted near the road.
  • The trees are more exposed to damage by snow plows, tall trucks, and vehicle crashes.
  • The roots can eventually push up the sidewalk, creating trip hazards and requiring repaving.
  • Bump-outs replace on-street parking, make it more difficult to plow and sweep, and are impossible in some locations, such as a bus stop (where a shade tree can be especially appreciated).
Trees in parks are great for many reasons and there should be lots of them, but they don't provide shade on the sidewalks and reduce heat islands over paved surfaces for people walking down the street or waiting for a bus. Also, tree aspiration cools the air around it, and absorbs carbon pollution from the air and releases oxygen, freshening the air around it. Also, a large tree can absorb 100 gallons or more water every day, helping to suck up ground water and reduce the next flood in the street or your basement. Shade trees near the street serve a purpose that trees in parks don’t, by making a streetscape more pleasant for much of the year.
We are not sure whether the Town can require owners to plant trees on their private property (although it could be incentivized), but we do believe many owners want to plant trees in their front yards for reasons in addition to just liking trees, birds and shade. Numerous studies have shown that trees increase the value of an urban property by 3-15%, so presumably trees planted in front yards should increase a property's selling price or rent. For example, see the following articles: Branch Out! How Trees Can Affect the Value of a Home and Want to Boost the Value of Your Home? Plant a Tree — Right Now.  As a sweetener, a Massachusetts law allows a town to plant trees for free in the front area of private property for the public good (MGL c, 87, s. 7).  Arlington’s Tree Warden and Tree Committee are in the process of developing this program for use especially in areas where there are no, or too small, tree strips for street trees or at multifamily or commercial properties with few or no trees planted on the street side of the building.

Livability & the Environment

Heat Islands are urbanized areas that experience higher temperatures than outlying areas. Structures such as buildings, roads, and other infrastructure absorb and re-emit the sun’s heat more than natural landscapes such as forests and water bodies. Urban areas, where these structures are highly concentrated and greenery is limited, become “islands” of higher temperatures relative to outlying areas. Daytime temperatures in urban areas are about 1–7°F higher than temperatures in outlying areas and nighttime temperatures are about 2-5°F higher. Find more information on the Learn About Heat Islands page." EPA - Heat Islands

View the results of the Wicked Hot Mystic through the interactive map produced by the Mystic River Watershed Association.

With climate change, rainstorms sufficient to cause street flooding are becoming more common. To reduce flooding, we need to provide more permeable surfaces so rainwater can be absorbed directly into the ground instead of running into the street and overloading the storm sewer system.
  • Rain gardens are collection areas that retain and filter rainwater using flood-tolerant plants, shrubs, and trees.
  • Large trees can absorb as much as 150 gallons of water a day, most of which evaporates through the leaves and provides additional cooling.
The minimum 15’ setback we recommend is a perfect locations for neighborhood rain gardens and large trees.


Here's the zoning code definition, which you can find in Arlington's Zoning Bylaw. Setback: The shortest horizontal distance from the front lot line to the nearest building wall or building part not specifically excluded in Section 5. Section 5 says that porches, decks, steps, and landings are not considered to be within the foundation wall. Detached garages are treated separately from the principal building and renewable energy installations enjoy some leeway. There are some fairly complicated calculations that are illustrated on the pages preceding Section 6.
SITES is a rating system that guides, evaluates and certifies a project’s sustainability in the planning, design, construction and management of landscapes and other outdoor spaces. Arlington's Environmental Design Guidelines currently does not require SITES. Green Street Arlington recommends SITES be added. You can find more information about SITES here.

MBTA Communities Action Plan

  1. The MBTA Communities Working Group deliberates and makes a recommendation to Arlington's Redevelopment Board (ARB).
  2. The ARB reviews, edits and completes the plan.
  3. The plan is reviewed by Arlington's Planning & Department Department.
  4. The Planning Department submits the plan to the state's Executive Office of Housing and Livable Communities (EOHLC) for approval.
  5. EOHLC confirms compliance, or returns the plan with comments for modification.
  6. After EOHLC, the plan is submitted as a warrant article to Arlington's Town Meeting for final approval.