The chemistry, mineralogy, and rates of transport of sediments in the ...

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that increased suspended and deposited sediments in small streams and
lakes resulted in reduced abundance of zoobenthic organisms . Rosenberg
(in prep .) indicated that increased sedimentation above 50 g m-2 of
stream bottom in a 5 hr period in the Harris River caused increases in
zoobenthic organisms drifting away from the area of sediment addition .
From the above, it would appear that it is necessary to have
estimates of the natural rates of movement of suspended and deposited
sediments in streams in order to consider the effects of increased
s:edimentsupply on the stream ecosystem . Of the many factors that
influence stream discharge, suspended sediment load, and bed load, some
will likely be affected by construction and operation of roads and
pipelines . The objectives of this paper are to 1) estimate natural
suspended sediment transport rates for selected watersheds, 2) to
identify characteristics of streams or their watersheds that influence
the rate of sediment supply to a stream, and 3) to relate present and
projected . increased sediment supply A the stream bottom (the habitat of
aquatic organisms) and to the watershed area ( the source of stream
sediments) .
METHODS
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Samples for suspended sediments were taken in streams and rivers
with a) van Dorn samplers at the surface and at various depths, b) by
hand filling carboys or bottles at the surface, and c) by using depthintegrating
suspended sediment samplers (such as the US DH-48 sampler,
see Stichling, 1974) . Samples were taken when possible at the point of
maximum velocity and depth in the stream cross section . A few comparisons
of depth-integrated suspended sediment samples and samples taken by hand
filling a 20 L . carboy at the surface indicated that the latter method
yielded results within 20% of the former method . Samples were taken at
least monthly when possible in the open water period . In some cases,
fewer samples were taken from rivers that' presented logistic problems of
access during break-up and ice formation periods . Usually only one or
two samples per year were taken from the river sampling stations under
winter ice . Sampling stations were reached by freight canoe, skidoo, and
aircraft . In situ measurements of temperature, turbidity, and conductance
were made as described in Brunskill et al . (1973) .
In the Jean Marie River bedload experiment, 22 August 1973, cobbles
and boulders from 0 .100 to 27 kg dry weight were painted bright colors
(coded for weight classes) and replaced in the strew : bed, just below a
riffle, in a straight line perpendicular to the river channel . After one
year, the site was revisited and the distance travelled by the painted
stones was measured from a tape stretched across the river at the site
of the original placement of the stones .