Urban forestry is the planning, establishment, protection, care, and management of trees within and around human settlements.

The Department of Natural Resources (DNR) is authorized to establish an urban and community forest program to encourage planning for, planting, and managing trees in the state's cities, counties, and tribal lands; to maximize the potential of tree and vegetative cover in improving the quality of the environment; to coordinate activities to develop and implement urban forestry programs in the state; to improve human health through delivery of programs and activities in highly impacted communities with health disparities; and to contribute to salmon and orca recovery through programs in regions that include important salmon habitats.

The DNR must identify priority regions for the implementation of urban forestry programs.  The determination of priority regions must include, but is not limited to:  analysis of tree canopy and urban forest inventory; use of health disparity mapping tools to identify highly impacted communities; review of salmon and orca recovery data; and use of the DNR's 20-year forest health strategic plan.  The DNR may consult with outside experts in establishing the priority regions.  Through the use of these tools and analyses, the DNR must identify areas where urban forestry will generate the greatest benefits in terms of tree canopy needs, health disparities, and salmon habitat.

The DNR may also advise, encourage, and assist cities, counties, and tribes in establishing urban forestry programs.  The DNR must provide technical assistance to cities, counties, tribes, and other public and private entities in developing these programs.  The DNR may provide assistance to communities developing urban forestry management plans or in developing urban forestry ordinances.

Many communities do have such ordinances.  These ordinances can regulate, limit, or prevent the removal of trees within the community in order to maintain tree canopy.

For example, in the City of Kirkland, trees that measure more than 6 inches in diameter when measured 4-1/2 feet off the ground are considered regulated trees.  Trees that measure more than 26 inches in diameter are considered landmark trees.  The removal of such trees from private property requires either notification or a permit, as well as proof of mitigation of the removal through the planting of additional trees. 

The City of Olympia has set a minimum number of tree units that must be maintained on a property.  If the removal of a tree would drop the property below that number, then a permit is required.

These regulations can also regulate tree removal during development.  In the City of Renton, for example, a land development permit is required prior to tree cutting, removal, or land clearing.  The City of Sammamish requires that special measures be taken during construction to retain and protect trees from construction damage.

Urban heat islands are urban areas that experience higher temperatures than surrounding areas.  Buildings, roads, and other infrastructure absorb and re-emit more heat than do areas with natural landscapes, leading to increased temperatures in areas like cities where infratructure, roads, and structures are highly concentrated.

A tree bank is an area or areas designated by a community in which trees can be planted to compensate for the removal of trees to enable development elsewhere.

Any city or town that has or enacts an urban forestry ordinance must allow for any obligations for the protection and management of trees imposed by the ordinance to be satisfied by the use of a tree bank.

The DNR must establish guidelines for the incorporation and use of tree banks within urban forestry ordinances.  The guidelines must establish criteria for designating tree banks, including that tree banks must be located in areas identified by the DNR as priority regions or areas suffering from the urban heat island effect.  The guidelines must also use the best available science to determine the appropriate ratio of trees added to the tree bank in order to compensate for trees removed elsewhere in the community, the appropriate species of tree to be used in the tree bank, and how to effectively support urban forest management plans through the use of a tree bank.