Subject: Re: Deepen the Columbia?
Date: Feb 18 14:09:21 1996
From: Teresa Michelsen - tcmnem


Jon asks,

>I'd like to know what effects the removal of an extra three feet of river
bottom will do for (or against) the wildlife and fisheries of the lower
Columbia and its estuary? Where will this sediment be placed, and what
effect will it have on bird life and juvenile salmonid habitats? There's a
lot of money to be made for shippers if they can get bigger freighters up
the River.
>

At the risk of being disapproved of by conservationists, I'm not sure that
lowering the river bottom from 40 to 43 feet deep is a major issue,
environmentally speaking. The river bottom is almost certainly not at its
preferred depth already, and may have to be dredged periodically to keep it
at 40 feet. Birds are not likely to know the difference, since they don't
use subtidal areas extensively, nor do juvenile salmonids, which tend to
spend much more time along the shoreline where there is food and they are
safer from predators. The shipping channels usually run down the center of
the river and leave areas near the shoreline alone. This is a minor
deepening proposal compared to some I've seen lately in Puget Sound. It may
depend on the length of the area they plan to dredge, which was not
mentioned in your post, as to how significant of a project this really is.

Where they might put the sediment is another matter. This would seem to be
the main place to concentrate your efforts in commenting on such a proposal.
If they dump it in productive intertidal areas, or use it for nearshore fill
for development, then it;s likely to have a detrimental effect. On the
other hand, there are numerous uses for clean dredged material that are
beneficial from an environmental point of view. Among them, restoration of
lost intertidal habitat, capping or otherwise cleaning up contaminated
nearshore areas (of which Portland has many), just to name a couple. Use of
clean navigational dredging material is a really inexpensive way of
accomplishing restoration or cleanup projects that would otherwise need an
expensive source of material and has often provided a way to get these
projects done that wouldn't otherwise exist. The Dredged Material
Management Office of the Corps of Engineers, Seattle District, EPA, DNR, and
Ecology have pioneered a cooperative program to try to encourage the
beneficial reuse of clean dredged material rather than just dumping it at
the nearest aquatic disposal site. Although this program has not yet
reached Portland District, it has been presented at dredged material
conferences there and could be implemented with a nearby role model.

Teresa Michelsen, Dept. of Ecology
tcmnem at halcyon.com