Small-Scale Suction Gold Dredging

1
Small-Scale Suction Gold Dredging
Presented by Joseph C. Greene, Research Biologist
Prepared for a Meeting with Oregon State
Legislators, Oregon Small-scale Miners, and US
EPA Region 10 Representatives
March 9, 2006 Oregon House Of Representatives
Office Building, Salem, Oregon
2
Small-Scale Suction Dredging and the
Environment

• It is my opinion that the results from scientific
  investigations, presented in the Environmental
  Impact Reports, prepared by the State of
  California, Clearwater National Forest and
  Siskiyou National Forest, provide all the
  evidence required to support the determination
  that small-scale suction dredging is
• de minimis
• and impacts from these dredges are
• less than significant.

3
Many people want outdoor settings to be left in a
natural condition for quiet enjoyment. Thus
suction dredging is perceived as a conflict with
these activities. The noise of the suction
dredge engines and exhaust fumes and the presence
of the suction dredge activities may be the very
things many people go outdoors to escape.
However, suction dredgers also enjoy the
outdoors. (CDFG, page V25)
The Real Problem
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The Real Problem

• It should be noted that suction dredging is
  considered a legitimate activity on rivers and
  streams and suction dredge operators have a
  Federally mandated right to operate. Dredgers
  also have the basic right, of all citizens, to
  enjoy and utilize streams as long as their
  activities are in compliance with the laws and
  regulations of the State.

ORS 541.110 provides, the use of water of lakes
and running streams of Oregon for the purpose of
developing the mineral resources is declared to
be a public and beneficial use and a public
necessity.
5
For discussion the following excerpts were taken
from the Draft Environmental Impact Report,
Adoption of Amended Regulations for Suction
Dredge Mining. 1997. State of California, Dept.
of Fish and Game. The Conclusions in this
report concur with those found in the Clearwater
and Siskiyou National Forest Environmental Impact
Reports.
These documents are the culmination of literature
searches for scientific evidence regarding the
impacts of small-scale suction dredging on the
environment and consultations with stakeholders
and concerned citizens.
6
Research to Support the Siskiyou National Forest
DEIR

• The SNF engaged Dr. Peter B. Bayley, Dept.
  Fisheries Wildlife, Oregon State University, to
  conduct a Cumulative Effects Analysis on the
  effects of suction dredging forest-wide

Dr. Bayley concluded
"The statistical analyses did not indicate that
suction dredge mining has no effect on the three
responses measured, but rather any effect that
may exist could not be detected at the commonly
used Type I error rate of 0.05."
(In other words, if there is an effect, it's so
small they can't measure it.)
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Dr. Bayley continued

• "The reader is reminded of the effect of scale.
  Localized, short-term effects of suction dredge
  mining have been documented in a qualitative
  sense. However, on the scales occupied by fish
  populations such local disturbances would need a
  strong cumulative intensity of many operations to
  have a measurable effect."

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Dr. Bayley concluded

• "Given that this analysis could not detect an
  effect averaged over good and bad miners and that
  a more powerful study would be very expensive, it
  would seem that public money would be better
  spent on encouraging compliance with current
  guidelines than on further study."

Now, back to the comments published in the
California Department of Fish and Game Draft
Environmental Impact Report.
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The area or length of river or streambed worked
by a single suction dredger as compared to total
river length is relatively small compared to the
total available area.
An individual suction dredge operation affects a
relatively small portion of a stream or river. A
small-scale suction dredge (representing
90-percent of all suction dredges) may spend a
total of 4 to 8 hours per day in the water
dredging an area from 1 to 10 m2 (3-33 ft2).

• The average number of hours spent is 5.6 hours
  per day. The remaining time is spent working on
  equipment and processing dredged materials.

10
Current regulations on most rivers and streams,
in conjunction with riparian protective measures,
results in a less than significant impact to
channel morphology.
Turbidity and sedimentation levels generally
return to background levels within 20 to 80 m
(66-263 ft) below the dredging activities.

• In many of the studies performed on suction
  dredging, potentially adverse impacts to river
  resources were reported. Effects of increased
  turbidity levels and sedimentation, decreases in
  invertebrate populations and re-configuration of
  the streambed were temporary and localized.

11
Suction dredging can have significant short-term
and localized adverse impacts on local benthic
invertebrate abundance and community composition.
However, over the long-term, the impacts appear
to be less than significant.
Colonies of invertebrates generally re-colonize
areas disturbed by suction dredges within a
relatively short period of time ranging from one
to two months. Impacts to benthic invertebrate
communities, from suction dredging, appear to be
less than significant.
12

• Effects to benthic and/or invertebrate
  communities, turbidity and water quality appear
  to be less than significant.
• They are usually localized and temporary in
  duration!

13
Effects from elevated levels of turbidity and
suspended sediment normally associated with
suction dredging as regulated in the past in
California appear to be less than significant
with regard to impacts to fish and other river
resources because of the level of turbidity
created and the short distance downstream of a
suction dredge where turbidity levels return to
normal.
Impacts on Fish
ADULTS

• Suction dredging appears to have little direct
  immediate physical effect on adult fishes in
  terms of harm from actual entrainment by dredges.

14
Yolk Sac Fry
Impacts on Fish
Juveniles
Entrained through a suction dredge does not
appear to have a significant adverse effect on
juvenile fish either.

• Entrainment can have a significant adverse effect
  on the more delicate stages of fish such as the
  yolk sac fry. During this stage the yolk sac can
  be easily ruptured or torn from the fish.

Eggs
Developing eggs of salmonids are significantly
adversely affected by entrainment through suction
dredges. The degree of harm may vary depending
on species.
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Impacts on Fish
Fish eggs and yolk sac fry are protected by
seasonal regulations that keep small-scale
suction dredgers out of the rivers and streams
during this season.

• Current law requires that dredging operations
  must stop or move if redds are present during a
  permitted In Water Work Period. 

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Impacts on Spawning Gravel
Most of the effects related to turbidity and
sedimentation, and the disturbance of spawning
gravels reported were temporary and localized,
and therefore, represented impacts considered
less than significant.

• Dredge piles do not appear to occupy a
  significant portion of the available spawning
  habitat so that dredge pile impacts are expected
  to be
• less than significant

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Impacts on Spawning Gravel
Approximately 60 salmonid redds were observed in
a study on Canyon Creek, CA. None of the redds
were found within dredge tailing piles.

• Once tailing piles are dispersed by high stream
  flows they do make up a component of the suitable
  spawning substrate.

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Salmonids do not spawn in this type of coarse
overburden
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Turbidity
It has been asserted that salmon were not
affected by elevated turbidity but studies have
stated that salmonid growth was reduced at 25 NTU
but not below.
Turbidity caused by suction dredging is highly
variable. Suction dredging bedrock pockets
containing only sand and gravel causes virtually
no change in turbidity whereas suction dredging
clay deposits causes very noticeable turbidity.
20
Flood Stage, Klamath River above Portuguese
Creek, 2006
21
Klamath River water The left vial was allowed to
settled for 24-hours, the right vial was shaken
to re-suspend the particulates. The sample was
measured at 656 NTU.
22

• People with agendas
• often dont put facts in perspective
• and blur the difference
• between facts and speculation

23
Turbidity plumes, usually, do not cover wide
areas of the stream and they are not continuous
or consistent in sediment content
24
Turbidity
Effects of the levels of turbidity and suspended
sediment normally associated with suction
dredging appear less than significant with
regard to the health or physiology of adult and
juvenile salmonids, particularly when one
considers that turbidity levels return to normal
levels on an average of 20-80 m (66-263 ft.)
below the suction dredge. Also, natural levels
of turbidity may be higher than levels of
turbidity caused by suction dredging during
certain times of the year.
25
Notice the switch in plume turbidity density.
Now the distant dredge plume is lower in suspend
material concentration
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• United States Department of Agriculture Forest
  Service Siskiyou National Forest, 200 NE
  Greenfield Road, Grants Pass, OR  97526-0242
• Reply to 2800 Date October 16, 1995
• Subject A comparison of stream materials moved
  by mining suction dredge operations to the
  natural sediment yield rates
• To The Record
• There are 1,092,302 acres on the Siskiyou
  National Forest. Using a factor of 0.33 cubic
  yards per acre per year times 1,092,302 acres
  will produce a very conservative estimate that
  331,000 cubic yards of material move each year
  from natural causes compared to the 2413 cubic
  yards that was moved by suction dredge mining
  operations in 1995 on the Siskiyou. This would be
  a movement rate by suction dredge mining that
  equals about 0.7 of natural rates.
• MICHAEL F. COOLEY, Recreation, Lands and Minerals
  Staff Officer, Siskiyou National Forest

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Constructing a nice deep hole for fish habitat
while producing an almost imperceptible turbidity
plume
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Fish Feeding
Fish have been observed feeding in turbid plumes
created by suction dredging. Stern (1988)
observed young steelhead feeding on dislodged
invertebrates in turbid dredge plumes, even
though clear water was available nearby.
Cutthroat and rainbow trout have also been
observed feeding.
The effects of suction dredging on the feeding of
fish appears to be less than significant.
Although invertebrate populations are negatively
affected by suction dredging, the impacts are
localized and short-term.
29
Fish feeding below outfall from a small-scale
suction gold dredge sluice box
30
Behavior and Distribution
Studies in Canyon Creek, Butte Creek, and the
North Fork American River, CA did not indicate a
difference in fish distribution or density below
or above suction dredging sites.
Stern (1988) reported that suction dredging did
not appear to influence the behavior of adult
spring-run salmonids in their summer holding
areas.
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Behavior and Distribution
Abandoned dredge holes can provide holding and
resting areas for fish. Stern (1988) observed
young steelhead in active and abandoned dredge
holes in Canyon Creek.
Suction dredge operators report adult salmon and
steelhead moving into dredge holes overnight.
Dredge holes often provide thermal and deeper
water habitat for fish and some dredge holes in
the Scott River, CA have held more juvenile
salmonids than adjacent habitats.
32
Benefits to the Environment
Small-scale suction dredge miners remove lead
shot, fishing sinkers, bullets and other metals
and fragments from streams and rivers. Removal
of these materials by suction dredgers is
considered a benefit to the environment.
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Intention of Congress

• "The development of information which describes
  the relationship of pollutants to water quality
  is essential for carrying out the objective of
  the Clean Water Act.  This information, known as
  criteria, is required under Section 304(a) to be
  developed and published by the Administrator and
  issued to the states and public.  Criteria to be
  developed in this section should draw upon the
  best scientific knowledge on the subject,
  including information, if any, from the National
  Academy of Sciences, the U.S Geological Survey in
  the Department of Interior, scholarly literature,
  academic experts, and other sources.

34
Establishing Effects of Pollutants

• Criteria establish the effects of pollutants on
  health or welfare, receiving water ecosystems and
  man, and identify the natural chemical, physical
  and biological integrity of the Nation's waters.

The concentration and dispersal of pollutants
and their by products through biological,
physical and chemical processes and any related
changes in the diversity, productivity, or
stability of receiving water ecosystems would be
part of the information provided.
35
Natural Integrity of Waters

• may be determined
• Partially by consultation of historical records
  on species composition
• Partially from ecological studies of the area
  or comparable habitats and,
• Partially from modeling studies which make
  estimations of the balanced natural ecosystem
  based on available information.

36
USEPA Fact SheetJanuary 14, 2000
On Nov. 18, 1996, EPA and the two environmental
groups entered into a settlement agreement to
resolve the challenge to the general permit. The
proposed permit sets conditions on the discharge
- or release of pollutants from the operation
into waters of the United States.
The settlement agreement required EPA to complete
two studies related to the impact of placer
mining on the natural environment in Alaska. One
was to address the discharge of metals by placer
mining operations and the other was to address
the impact of suction dredge mining.
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FINAL REPORT Submitted June 1999Prepared For
US Environmental Protection AgencyRegion
10Seattle, Washington Prepared ByAaron M.
Prussian, Todd V. Royer, and G. Wayne Minshall
Department of Biological SciencesIdaho State
UniversityPocatello, Idaho 
Impact of Suction Dredging on Water Quality,
Benthic Habitat, and Biota in the Fortymile
River, Resurrection Creek, and Chatanika River,
Alaska
38
Alaska Study Summary

• The report described the results of research into
  the effects of commercial and small-scale suction
  dredging on the water quality, habitat, and biota
  of Fortymile River, Resurrection Creek and the
  Chatanika River, Alaska.

Focus of the work on Fortymile River was on an
8-inch suction dredge located on the main stem
and a 10-inch suction dredge located on the South
Fork.
39
Alaska Study Summary

• Water chemistry measured on Fortymile River
  showed the primary effects of suction dredging
  were increased turbidity, total filterable
  solids, and Cu and Zn concentrations downstream
  of the dredge.

The results from this sampling revealed a
relatively intense, but localized, decline in
water clarity during the time the dredge was
operating. These variables returned to upstream
levels within 80-160 m (263-524 ft.) downstream
of the dredge.
40
Alaska Study Summary

• Cross-sectional profiles indicate that the impact
  of the dredge piles relative to the width of the
  Fortymile River was small.

Macroinvertebrate abundance and diversity were
greatly reduced in the first 10 m (33 ft.) below
the dredge but returned to values seen at the
reference site by 80 to 160 m (263-524 ft.)
downstream of the dredge.
One year after dredging on the main stem and
South Fork of Fortymile River, recovery of
macro-invertebrate diversity appeared to be
substantial.
41
Alaska Study Summary

• The second component of this project is to
  examine the effects of small-scale suction
  dredging on smaller streams in Alaska.

Sampling was conducted on Resurrection Creek and
on the Chatanika River, Alaska.
The results from Resurrection Creek showed that
there was no difference in the macro-invertebrate
communities between the mining area and the
locations downstream of the mining area, in terms
of macroinvertebrate density, taxa richness, EPT
richness, or food resources.
42
Alaska Study Summary
Results from the Chatanika River showed slight
downstream decreases in macroinvertebrate
density, but all other measures remained similar
to those of the reference area.
In general, the results are in agreement with
other studies that have found only localized
reductions in macroinvertebrate abundance in
relation to small-scale suction dredging.
43
USEPA Fact SheetJanuary 14, 2000The U.S.
Environmental Protection Agency (EPA)Plans To
Issue A Wastewater Discharge Permit ToAlaska
Mechanical Placer MinersThis will also serve
as a notice of a
FINDING OF NO SIGNIFICANT IMPACT
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USEPA Fact SheetJanuary 14, 2000

• The environmental groups believed that the
  suction dredge report (40-mile River,
  Resurrection Creek, and Chatanika River) did not
  address all of the required elements as set out
  in the 1996 settlement agreement.

To avoid further litigation over the general
permits, EPA and the environmental groups entered
into another settlement agreement.
45
The EPA had chosen to flex its legal muscle where
scientific data does not justify their actions.
Other Federal Agencies have stated the following
. . . For decades, suction dredging has been
essentially unmanaged. Its effects were
considered insignificant and its consequences
immeasurable. (Siskiyou National Forest Draft
Environmental Impact Statement).
And, the U.S. Army Corps of Engineers stated, To
regulate against a potential for harm, where none
has been shown to exist, is unjustifiable and
must be challenged."
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Presented by Joseph C. Greene, Research Biologist
(March 9, 2006 in Salem, Oregon)