Here is what is currently in place as to removing trees in Seattle as of November 2013.  .

The “interim” tree ordinance passed in 2009 by the Seattle City Council is the governing ordinance. It came about because of the loopholes in removing trees in Seattle exposed by two citizen battles.  Protecting trees in the Northwest Grove at Ingraham High School in North Seattle and saving Waldo Woods in the Maple Leaf area.

Here is the Seattle City Council’s press release when they passed the interim ordinance:
http://www.seattle.gov/council/newingsdetail.asp?ID=9395&Dept=28
This lists a fine of up to $5000 for violating the ordinance.

Actual ordinance: Council Bill 116404
http://clerk.ci.seattle.wa.us/~scripts/nph-brs.exe?s1=&s2=&s3=116404&s4=&s5=&Sect4=and&l=20&Sect2=THESON&Sect3=PLURON&Sect5=CBOR1&Sect6=HITOFF&d=CBOR&p=1&u=%2F~public%2Fcbor1.htm&r=1&f=G

Three  DPD  memos further explain the requirements:

Tree Protection Regulations in Seattle:
http://www.seattle.gov/dpd/publications/cam/cam242.pdf
This states that no exceptional trees may be removed on developed property over 5000 square feet.

Designation of Exceptional Trees:
http://www.seattle.gov/dpd/codes/dr/dr2008-16x.pdf
This one clarifies what an exceptional tree is and has a list of tree sizes for trees.  For example it states that for Douglas firs,  trees larger than 30 ” in diameter are exceptional and may not be removed unless they pose a hazard.

Seattle Permits -Removal of Hazard Trees – includes Hazard Tree Removal Application
http://www.seattle.gov/dpd/publications/cam/cam331b.pdf

The interim ordinance  is clearly lacking as large trees continue to be  cut down without regard for their size.  There is also no requirement for replacement trees.

Seattle has been working on updating the tree ordinance for four years now.  The Seattle Department of Planning and Development has come up with several drafts which have not been acceptable to members of the public and others.  DPD’s approach has been contrary to the direction of the Seattle City Council which wanted stronger regulations to protect trees.DPD currently does not require or enforce getting permits to remove most trees in the city.  They have operated what they call a complaint system which doesn’t work because there is no way to stop someone cutting down a tree and a complaint after the fact doesn’t save any trees.

DPD’s draft proposals for this reason were also not viewed  favorably by the Seattle Urban Forestry Commission.  The next draft of  a proposed tree ordinance was to be released in Jan or Feb 2014.  This is now most likely up in the air as the current Mayor, Mike McGinn, was defeated in the Nov election and  the new Mayor, Ed Murray,  is likely to view this issue with fresh eyes..

Any new ordinance to be successful needs to require permits to remove any tree over 8 – 10  inches in diameter and require a  two week posting of all proposed tree removals so any conflicts can  be addressed. Also unless replacement of trees cut down is required, either on site or off site, Seattle will continue to lose canopy.  This is despite the Seattle Comprehensive Plan stating a yearly goal of no net loss of canopy..

Cities like Portland, OR; Vancouver, WA, Lake Forest Park,WA and Kirkland, WA currently require permits to remove large trees. Permits are currently required by SDOT to prune or remove trees in the right of way and by DPD to remove hazard trees (although  there is little or no evidence this is working).