Subject: [Tweeters] 520 bridge construction, Foster Island
Date: Jul 27 12:37:27 2012
From: Tim Billo - timbillo at u.washington.edu


Many of you on this list are probably following the construction plans for
the 520 interchanges in the Montlake/Arboretum area and probably have more
updated information than I. But I thought I would bring it to people's
attention anyway.

I had a student in my UW ornithology class this spring do a mini project
on this area, in which he identified bird species regularly occurring or
breeding there, and then looked at the potential impacts of the new
bridges on those species.

Many of you are familiar with the amazing system of wetlands around Marsh
Island, and you know that despite the road noise, a high diversity of
birds can be seen here throughout the year. While many species will likely
be at least temporarily affected until habitat returns to its current
state, he identified a few species he thought were of special concern.
One, the Green Heron, is listed by the state of Washington Department of
Fish and Wildlife as "sensitive." It seems probable that this species
breeds in the area, as it is frequently seen along the 520-facing edge of
Marsh Island. As far as my student could tell, the new bridge proposal
involves widening the 520 bridges out to the edge of Marsh Island,
potentially severely degrading habitat along the edge of those islands
where the herons are most often seen. Assuming that widening in this area
is a foregone conclusion, he proposes at the very least, restricting
construction to periods of the year that are outside the breeding season
for the Green Heron and other species that breed there.

He also notes the Cliff Swallow breeding colonies on these bridges which
will be directly affected by the construction and again suggests limiting
construction to the non-breeding season. Presumably the colony would
re-form once the new bridge is in place.

Construction is already in full swing on the east side of the lake and
over the main span of the bridge. It still seems there is a lot of
worthwhile debate going on on the west side about putting in a bike path
along the brdiges all the way through to I-5 (currently not in the plans)
and whether we even need wider bridges through these sensitive wetlands in
the arboretum anyway (since tolling already seems to have controlled the
original traffic problem). I believe the latest plans will be able to
accommodate light rail, which seems like the most crucial piece if
this bridge is an essential component of planning for future growth in the
region (but if I remember right it took some pushing to get that).

Nevertheless, as the birding community it will be important to keep
monitoring this important Seattle wetland as development plans unfold. I'm
sure there is a monitoring plan in place but can't hurt to have more
citizen eyes and ears out there.


Cheers,

timbillo at uw.edu

P.S. Thanks to everyone I ran into in the field this spring with my
course, and for all of the great postings on this site. You helped make
some of our fieldtrips this spring much more productive.