Portland-Milwaukie Light Rail Project - FEIS - Volume 1 - TriMet

In-water habitat impacts due to the installation of piers and scour protection in the Willamette
River will be offset through the removal of identified derelict pile fields and through the
creation and enhancement of shallow water and beach habitat within the active channel of the
Willamette River at a site known as the Central District or South Waterfront Greenway,
upstream of the Ross Island Bridge on the western bank. Further detail is included in Section
3.8.3.2.
Kellogg Lake
In the project area, Kellogg Creek is impounded to form Kellogg Lake, which currently lacks
the water velocity of a free-flowing stream and has very little habitat diversity. Consequently,
the quality and diversity of the lake’s fish habitat is low and, because velocities are very low,
the impact of the in-water bridge structure to existing habitat and channel integrity, primarily
by scouring, is minimal.
The shafts of the in-water pier would likely be small (two 6-foot columns) relative to the size
of Kellogg Lake (100 feet wide). Depending on the final design of the bridge pier, total area
and volume of the waterbody impacted by the piers would likely be less than 10 percent of the
water column. Analysis and reduction of hydraulic effects from piers could allow for
unimpeded flow under most conditions.
Crystal Springs, Johnson, Crystal, Spring, and Courtney Springs Creeks
Crossings of the other streams would occur with the use of bridge structures above OHW (at
Crystal Springs Creek and Johnson Creek), by utilizing and repairing existing culverts (Spring
Creek and Courtney Springs Creek), or by extending an existing culvert (Crystal Creek). At all
crossings, the project would adhere to applicable regulations and policies, including use of
approved in-water work windows and stormwater management requirements. Unavoidable fill
located in the channel or floodplain also would be offset by a balanced cut, reducing impacts to
floodplain function and stream hydrology.
At Westmoreland Park, Crystal Springs Creek will be rechanneled and revegetated with wetland
and riparian plants. The project will partially fund this City of Portland project to mitigate
wetland impacts along the project corridor. Long-term effects of this project include controlling
water temperatures, improving water quality, and restoring in-stream habitat complexity to
benefit native fish species present in Crystal Springs Creek and the Johnson Creek watershed.
Fairview Creek
At the Ruby Junction Facility, no structures are proposed to be built within Fairview Creek or its
floodplain. If structures were constructed in the floodplain or if it were otherwise encroached
upon, balanced cut and fill would be required. In addition, necessary stormwater treatment from
any new construction would result in minimal impacts to surface water or groundwater
resources.
Long-Term Indirect Impacts
Long-term indirect impacts typically are associated with increases in impervious surface area.
Impervious surface can have an adverse impact on hydrology and water quality for four reasons:
3-162 Portland-Milwaukie Light Rail Project FEIS
Section 3.8. Ecosystems