Q.
Is there a pressing timeline to get the dredging done?
A.
Dredging in the navigation channel in the Snake River is restricted
to an in-water work window set by National Marine Fisheries Service
in coordination with state fishery agencies. For the Snake River,
the window is typically set at December 15 to March 1.
Q.
If the Corps does not dredge this winter, will the Corps perform
emergency dredge operations?
A.
If an injunction is still in effect, the Corps could petition
the court prior to any emergency dredging. The scope of such
dredging would depend upon the situation and whether permitted by
the court. If determined necessary, and permitted by the court, the
Corps would attempt to perform the emergency dredging in a manner
that minimizes any adverse effects on the environment. For an
emergency dredging situation, the Corps would, on an expedited
basis, perform environmental coordination as necessary, including
coordination with the National Marine Fisheries Service and the U.S.
Fish and Wildlife Service. The Corps obtained a water quality
certification in preparation for dredging this year to avoid further
reduced channel depths and the accompanying adverse impacts to
shipping. Because of the increased sediment carrying capacity of a
large runoff event, if one occurs next year or in the future, enough
sediment could be deposited to significantly reduce channel depths.
Q.
Costs of dredging in 2002 - 2003?
A.
A contract for dredging on the Snake River was awarded to Dutra Dredging
Company, San Rafael, Calif., in October. The cost of the contract
was for $2.4 million. The contract was terminated on Dec. 27, 2002.
Costs related to terminating this contract will
be negotiated between the contractor and the government.
Q.
What are the economic benefits of maintaining the lower Snake River
navigation channel?
A.
The costs savings of transportation by barge on the lower Snake
River, compared to other transportation methods, are estimated to be
$43 million a year. The
lower Snake River waterway is 141 miles from the confluence with the
Columbia River to Lewiston, Idaho. In 2000, 6.7 million tons of
cargo was transported on the waterway. The majority of the cargo
shipped was agricultural products and petroleum.
Q.
What impact does dredging have on fish? What steps has the Corps
taken to minimize this effect?
A.
Dredging
and disposal of dredged material is expected to have minor short
term negative impacts to fish using the activity areas during the
dredging and disposal period. The dredging proposed will use the
most fish friendly equipment possible, at a time of year when the
fewest fish are expected to be in the dredging areas, and under
strict monitoring conditions for turbidity and water chemistry
parameters that may impact fish. Prior to dredging any areas that
might be used by salmon as spawning areas (i.e. the downstream
navigation lock approaches), the Corps will conduct redd surveys to
determine if any redds are in the area. Redds are the nests that
salmon lay eggs in. The Corps plans to do these surveys even though
studies have indicated that most of the area within the navigation
lock approaches dredging limits is not suitable for salmon spawning.
If any redds are found, the Corps will not disturb them and
will contact NMFS to determine if an adjusted dredging
activity can continue, or if the dredging planned for that area will
have to be rescheduled. For
the 2002 - 2003 dredging, the Corps has conducted redd surveys of
the two navigation lock approaches and has not found any redds.
The National Marine Fisheries Service and U.S. Fish and
Wildlife Service have agreed with the Corps’ plan for dredging
this year. NMFS has issued a Biological Opinion, which the Corps had
planned to implement prior to the injunction.
Q.
How does dredging benefit fish?
A.
One of the beneficial uses of dredged material includes in-water
disposal to create shallow water sand bars along shorelines of the
reservoir where there is currently deep water. The creation of this
habitat will attempt to mimic some of the conditions of the lower
Snake River prior to dam construction, and is expected to provide
benefits to some of the endangered salmon species by providing
resting and rearing habitat for juvenile salmon prior to their
downstream migration to the ocean. Roughly 8 years of research on
this type of habitat creation has shown that this method has good
potential to benefit juvenile salmon and does not tend to
concentrate predatory fishes such as bass and pikeminnow.
Q.
How does the Corps address water quality?
A.
The Corps’ proposed dredging and disposal activities are designed
to avoid or minimize adverse impacts to water quality. Each dredging
activity is evaluated in accordance with sampling and monitoring
plans developed specifically for that site. The monitoring plan for
the 2002 - 2003 dredging is posted on the District website. Each proposed dredging activity is reviewed by appropriate
water quality regulatory agencies as part of the Clean Water Act 401
certification process. The assessment determines whether any
disposal activity will cause or contribute to significant
degradation of the waters of the United States and appropriate
measures will be taken to address the situation. For the 2002 - 2003
dredging and disposal, the Corps obtained Clean Water Act Section
401 water quality certification from Washington Department of
Ecology.
Q.
Does the Corps test for contaminants and how will the Corps
determine if there are hazardous levels of contaminants in sediments
in the areas to be dredged?
A.
Yes, the Corps tests sediments for contaminants. However, the bulk
of the volume of dredged material from project area is made up of
large percentages of fine sand.
Most contaminants typically do not bind with the
larger-grained material such as sand. Limited industrial activity in
the project area also reduces the chance that hazardous levels of
contaminants are contained in the sediments in the project area.
Historic sampling and analyses of sediments prior to dredging
activities has supported these findings.
Q.
Has the Corps evaluated the sediment in the areas that were proposed to be
dredged?
A.
Yes, the Corps has tested and evaluated the sediment for the areas that are proposed to be dredged. Sediment quality evaluation
performed on samples from the proposed dredging areas, even in those
areas with higher concentrations of fine-grained material, did not
indicate contaminant levels that exceed regional and national
guidance regulatory action levels.
