
COMMISSION AGENDA
T. Yoshitani, Chief Executive Officer
May 28, 2009
Page 2 of 5
The Miller Creek Relocation was to be designed in a manner that maintained stream velocities
throughout the year such that the creek would provide cutthroat trout spawning habitat. Upon
completion of the project, it was determined that actual elevation grades were not sufficient to
maintain the desired minimum velocity.
Although the spawning habitat function was not provided, Port studies have shown that the new
channel does provide winter rearing habitat for cutthroat trout and coho. The agencies
recognized the importance of winter rearing habitat in the Miller Creek system, but required
compensatory measures be provided to make up for low velocities and associated lack of
spawning habitat. After extensive discussions with Port staff, the agencies agreed that removal
of a box culvert under 160
th
Street would compensate for the spawning habitat function not
provided by the relocated channel. The 160
th
Street box culvert is located on Airport property
approximately 2,000 feet downstream of the relocated channel and currently limits fish
migration.
In addition to the 160
th
Street box culvert, the agencies have required the Port to modify the
relocated channel by the addition of gravel on the sides of the creek to improve stream flow
characteristics and water quality.
The Commission fully authorized the Third Runway project which included the scopes of work
for the Miller Creek relocation and environmental mitigation requirements of the §404 and §401
environmental permits for the Third Runway. The Third Runway was opened on November 20,
2008.
PROJECT DESCRIPTION/SCOPE OF WORK
Project Statement:
Remove the 160
th
Street Box Culvert as compensation for the inability of the Miller Creek
Relocation Channel to meet a minimum velocity requirement and add gravel to the relocated
channel to improve stream flow characteristics and water quality.
Project Objectives:
Complete compensatory mitigation associated with the Miller Creek Relocation project to fulfill
permit obligations for the Third Runway.
Scope of Work:
Remove the concrete box culvert and the 160
th
Street bridge
Restore the Miller Creek channel in the culvert/bridge removal area
Enhance the relocated section of Miller Creek with additional gravel and woody
vegetation