20071889 Ver 1_More Info Received_20080305

07- 1U9
2-29-2008
Mrs. Cyndi Karoly
401 PERMITTING Unit
1650 Mail Service Center
Raleigh, NC 27699-1650
Dear Mrs. Karoly;
Please find enclosed four (4) copies of a letter that I sent to Mr. Kevin Barnett of the
Surface Water Protection Section on 1-7-2008. As you can see, I responded well within
the time frame laid out.
You will also find a copy of the cover letter that I sent to Mr. Barnett on the same day.
The agreement that we made when I met with Mr. Barnett was that he would go over the
letter with me and make sure that I had all items covered adequately so that I wouldn't
spend a lot of time writing back and fourth answering questions or providing added data.
That obviously didn't work. None of my calls were answered. I finally went to see the
section's supervisor. I don't have his name in front of me where I'm writing this letter.
He got things rolling again this last week and Mr. Barnett e-mailed me to send four
copies of my letter to you.
Please find enclosed the EPA Suction Dredge Study that I sent to Mr. Barnett for his
review. I wanted to make sure that there was enough data to support the fact that
recreational dredging is not harmful to a flowing body of water. I have read several
papers on the subject now and they all draw the same conclusion. Recreational dredging
is actually beneficial to a stream or river. A natural storm does more to disturb a river that
an 8" dredge does. We will be using a 6" dredge, by the way. You will need to go to the
Second component of the study to find the effects of recreational dredging.
By the way, Thermal City is adjacent to our land on the Second Broad River and has been
in operation since the civil war. I can't find a single negative remark about their operation
having any sort of negative effect upon the river over these many years.
I would appreciate it greatly if you would give this your immediate attention. The season
is upon us to begin dredging.
Thank you for your time and consideration.
Tom Bly
Cell: 864-505-4792
Home: 704-487-8296
e-mail: [e-mail] MAR 5 zoos
DENR - WATER QUALITY
VIANDS AND STORAIWATER BRANCH
O?p? W A ?F?pQG Michael F. Easley, Governor
William G. Ross Jr., Secretary
?- North Carolina Department of Environment and Natural Resources
Q Coleen H. Sullins, Director
Division of Water Quality
SURFACE WATER PROTECTION SECTION
December 13, 2007
SECOND MAILING 12/21/2007 DWQ Project # 07-1889
RETURN RECEIPT # 7006 3450 0002 7064 1519 Rutherford County
CERTIFIED MAIL
RETURN RECEIPT REQUESTED - 7006 3450 0002 7064 2288
Michael R. and Linda L. Bly
145 Blalock Road
Boiling Springs, South Carolina 29316
Subject Property: Linda's Place
Rutherford County
?oe4 B
MAR 5 2008
REQUEST FOR MORE INFORMATION
Dear Mr. and Mrs. Bly:
DENR - WATER QUAUTY
WETLANDS AND STORMWATER BRANCH
On November 7, 2007, the NC Division of Water Quality received your application for
stream impacts with respect to your proposed mining in the Second Broad River. Based
on our review of your submitted application, the DWQ has determined that your
application was incomplete and/or provided inaccurate information as discussed below.
The DWQ will require additional information in order to process your application to
impact protected wetlands and/or streams on the subject property. Therefore, unless
we receive the additional information requested below, we will have to move toward
denial of your application as required by 15A NCAC 2H .0506 and will place this project
on hold as incomplete until we receive this additional information. Please provide the
following information so that we may continue to review your project.
Additional Information Requested:
15A NCAC 02H .0506 (f) requires that "a lack of practical alternatives" be
demonstrated. No discussion in regards to mining the project without directly
impacting the aquatic resource has been presented. A discussion regarding
practical alternatives with respect to a reduction or avoiding of impacts must be
presented.
°EhCaro ina
Natimillf
North Carolina Division of Water Quality 2090 U.S. Highway 70 Swannanoa, NC 28778 Phone [phone] Customer Service
Asheville Regional Office Internet:: www.ncwaterouality.ora FAX [phone]
An Equal Opportunity/Affirmative Action Employer - 50% Recycled/10% Post Consumer Paper
Linda's Place
Page 2of 3
December 13, 2007
2. Application Item 111. requires a detailed site plan showing property boundaries and
development plans in relation to surrounding properties. The included plans do not
show the proposed development and lot locations.
3. Application Item III. 10. requests a description of the overall project. Your
submitted application details the impacts related to this activity as being "minor
and temporary." The submitted floating dredge (Keene 6 Inch Dredge) data
sheet states that "increased suction power will pull rocks from over a foot away
and move a tremendous amount of material." You must explain how this amount
of substrate disturbance is "minimal and temporary" to aquatic benthos.
Additionally, you must explain / demonstrate how you will not violate state
turbidity standards during the operation of the dredge (50 ntu).
4. Application Item XI. requests a stormwater management description for the entire
development, for the life of the proposed activity. You application provides no
discussion as to how stormwater will be managed.
Please respond before the close of business on January 14, 2008 by sending four
copies of this information to the 401 Permitting Unit at:
Mrs. Cyndi Karoly
401 Permitting Unit
1650 Mail Service Center
Raleigh, NC 27699-1650
and a single copy to the Asheville Regional Office at:
Kevin Barnett
Surface Water Protection Section
2090 US HWY 70
Swannanoa, NC 28778
If we do not hear from you before January 14, 2008, we will assume that you no longer
want to pursue this project and we will consider the project as withdrawn.
Linda's Place
Page 3of 3
December 13, 2007

This letter only addresses the application review and does not authorize any impacts to
wetlands, waters or protected buffers. Please be aware that any impacts requested
within your application are not authorized (at this time) by the DWQ. Please call Mr.
Kevin Barnett at 828-296-4657 if you have any questions regarding or would like to set
up a meeting to discuss this matter.
Sincerely,
1 e?q
Roger C. Edwards, Regional Supervisor
Division of Water Quality
Surface Water Protection Section
RCE/khb
cc: USACE Asheville Regulatory Field Office
David McHenry, Wildlife Resources Commission
Cyndi Karoly, 401 /Wetlands Unit
File Copy
Central Files
Filename: 07-1889.LindasPlace.Add-Info
1-7-2008
Hey Kevin,
Following is a close rough draft for you to look at with reference to our discussions on
"Linda's Place" near Thermal City, NC.
I'll call tomorrow to make sure that you received the draft. We can go over it on the
phone or I can come up, whichever suite you.
The EPA study will arrive via separate e-mail. Please place it with the draft for your
consideration.
Take care and thanks for your time and consideration.
Tom Bly
1-7-2008
Mr. Kevin Barnett
Surface Water Protection Section
2090 US 14WY 70
Swannanoa, NC 27699-1650
Dear Mr. Barnett,
With reference to the letter dated December 13, 2007 from the North Carolina Surface
Water Protection Section.
Item 1. Lind's Place is not a mining operation.
It is what the EPA in its "Suction Dredge Study-1999", "Impact of suction dredging on
water quality, benthic habitat, and biota in the Fortymile River, Resurrection Creek, and
Chatanika River Alaska" states is "Recreational Dredging".
I have acquired a great deal of information with reference to suction dredging with intake
pipes of 8" and less. The EPA says "Recreational dredges are smaller than those
examined on the Fortymile and typically have intake lines of 2-6 inches in diameter".
All of the studies that I have read and copied from on line have been completed in states
that are popularly known for gold deposits in waterways such as Alaska, California,
Montana, Washington and Utah. I couldn't find any studies completed in the eastern
mountain states. The studies, whether done by the EPA, state agencies or a university all
reach the same conclusion in the various studies as the one that I have enclosed.
The enclosed study contains quite a bit of information on "impacting the aquatic
resource". It is 17 pages made up of two (2) parts. Part I. studies the "Suction Dredging
in the Fortymile River "in relation to commercial suction dredging" using 8 " and 10"
dredges. Part II. Studies the "Recreational Dredging in Resurrection Creek".
Reading the EPA studies, the EPA considers the use of suction dredges up to and
including 8" as dredges used for Recreational Suction Dredging when there is not an
application submitted to a state for a MINING permit. I know from personal experience
that this is true in California. California limits the recreational suction dredge to 8".
"Impacts" were found to be "no significant differences", "not significant" from the
established means. You will find this information in the RESULTS paragraph in Part II
of the study.
Item 2.
You have, in your possession, a "detailed site plan". Please find another site drawing
enclosed. It is a surveyor's print and description of the land that Michael owns and is
named after his wife, Linda.
There is not any "proposed development and lot locations".
Item 3.
The description for the overall project is simply as stated above. The Second Broad
River, which runs through the property, will be used for Recreational Dredging.
This can't be called a project as there is nothing being altered or built that constitutes a
project. I have been involved in many "projects" over the years and "Linda's Place"
doesn't begin to qualify for such a designation. There will not be a quantity of earth
moved or commercial buildings built on the land. It's a family and friends recreational
area. There is no other way to describe what we are doing.
There will probably be a barn or large shed built at some point as well as picnic tables,
perhaps with shelter over them but that is residential and of no concern to the state of NC
with the exception of local building permits, where required.
To address the Keene Engineering marketing material statement "increased suction
power will pull rocks from over a foot away and move a tremendous amount of
material":
I talked with Mr. Mark Keene who, with his brother Pat and his father, own Keene
Engineering, stated that " the statement and wording is of a marketing nature". The
amount of material that they can "legally" show being moved is in the form of sand with
shell in it and with the dredge running at full throttle. There are no obstructions of any
kind. Mr. Keene states that the actual amount of material that can be moved in a
California river is on the order of two (2) cubic feet per minute. This is due to the fact
that dredging requires a lot more time to move underwater rocks out of the way, tending
to the dredge itself and the fact that dredge operators, including Mike and I, don't operate
dredges a full throttle. We operate our dredge at approximately 2/3 throttle. They will
pull a small rock, approximately 3" or less, from a foot away. All dredges that we have
used will pull rocks from a foot away, if it is loose on the river bed. The fact remains that
the river material is ALWAYS put back into the river within 10' to 20' of where the
dredge floats, we hope, with the exception of gold. No rock can be moved with the
dredge that is larger than 5" in diameter. It is our intention to weld a cross bar on the end
of the nozzle that will further reduce the size of rock that can be moved through the
dredge. The primary reason for this is safety. We don't want anything run through the
dredge that is very large.
Should you want to talk with Mr. Mark Keene or his brother Pat, I will provide their
phone number for you. Mark Keene said that he would be glad to talk with you, should
you want to do that.
Turbidity is discussed in the enclosed EPA study. Its not of any significance. In my
experience, you can see through the water at all times with the exception of near the
intake in sediment material. That settles or is washed away quickly. You are certainly
welcome to come and observe what we do. I would let you know what weekend we will
be up there and you can send someone out to visit. Please have them properly identify
themselves. We should, weather permitting, be there in April and into October or
possibly November.
Item 4
As previously stated, there is no development planned now or in the future. This is
strictly a recreational/hobby endeavor. The dredge will simply be floated on the river
when we are there and want to use it. This does not require a stormwater management
description. The Second Broad River will manage its own stormwater when storms occur.
Which reminds me, as a side note, some of the data that I have, states that a normal storm
disturbs a river far more than commercial dredging does. If you need a quote on this, let
me know and I will find it for you.
As a result, there is no storm water management description now, nor will there ever be.
Thank you for your time and consideration.
Sincerely,

Thomas K. Bly
704-487-8296
Cell: 864-505-4792
e-mail: [e-mail]
EPA Suction Dredge Study - 1999
Page 1 of 17
EPA Suction Dredge Study - 1999
Alaska Mining & Wing SUPply
Note: This is the full text of this report, but the accompanying tables are lacking. You may download the full
report with tables in Adobe pdf format at
http://www.isu.edu/departments/bios/Minshall/Publications/Report.pdf
Impact of suction dredging on water quality, benthic habitat, and biota in the
Fortymile River, Resurrection Creek, and Chatanika River, Alaska
Prepared For:
US Environmental Protection Agency
Region 10
Seattle, Washington
Prepared By:
Aaron M. Prussian, Todd V. Royer, and G. Wayne Minshall
Department of Biological Sciences
Idaho State University
Pocatello, Idaho
FINAL REPORT
June 1999
Table of Contents
Summary
Part I - Suction Dredging in the Fortymile River
Introduction
Methods
Racilitc
Discussion
Part II - Recreational Dredging in Resurrection Creek
Tntrnrii irtinn
Methods
Results and Discussion
Acknowledgments
Literature Cited
Summary
This report describes the results of our research during 1997 and 1998 into the effects of commercial
suction dredging on the water quality, habitat, and biota of the Fortymile River and recreational dredging on
Resurrection Creek and the Chatanika River. On the Fortymile River, water chemistry, heavy metal
concentrations, riverbed morphology, algal (periphyton) standing crop, and aquatic macroinvertebrate
abundance and diversity were measured in relation to commercial suction dredging for both years. The
focus of our work on the Fortymile in 1997 was on an 8-inch suction dredge (Site 1), located on the
mainstem and a 10 inch dredge located on the South Fork (Site 2a). Our research in 1998 included (1)
resampling the 1997 sites on the mainstem and SF Fortymile to determine recovery after one year, (2)
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sampling a dredge site on the South Fork to examine for possible spatial variability in the effects of large-
scale suction dredging on benthic communities (3) sampling a dredge site on the North Fork Fortymile to
determine whether impact and recovery differ from conditions on the South Fork and the mainstem, and
(4) again sampling unmined sites on the NF and SF to better document suspected background differences
between the two forks in terms of macroinvertebrate communities. In all of the suction-mined sites studied,
dredges were operated by experienced miners. Sampling was performed at fixed transects above and below
the dredge locations. Additional sampling above the confluence of the North and South Forks revealed
differences in background conditions in these two main tributaries.
At Site 1, dredge operation had no discernable effect on alkalinity, hardness, or specific conductance of
water in the Fortymile. Of the factors we measured, the primary effects of suction dredging on water
chemistry of the Fortymile River were increased turbidity, total filterable solids, and copper and zinc
concentrations downstream of the dredge. These variables returned to upstream levels within 80-160 m
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. The impact of suction dredging on water
clarity and heavy metal concentrations may be greater or lesser than we measured, depending on the type
of material the dredge is excavating.
The cross-sectional profiles indicate that the impact of the dredge piles relative to the width of the Fortymile
River was small. After one year, dredge piles at Site 1 had largely disappeared following the scouring flows
that accompany snow-melt in the Fortymile drainage. However, at Site 2, dredge piles were clearly
discernable after one year. Macroinvertebrate abundance and diversity were greatly reduced in the first 10
m below the dredge at Site 1 during 1997, relative to the upstream reference site. For example,
macroinvertebrate abundance was reduced by 97% and the number of taxa by 88% immediately below the
dredge. The abundance and diversity of macroinvertebrates returned to values seen at the reference site by
80 to 160 m downstream of the dredge. A similar decline in macroinvertebrate abundance and diversity was
observed at Site 2a. One year after dredging at both Site 1 and Site 2, recovery of macroinvertebrate
diversity appeared to be substantial. The cumulative effect of suction dredging on the biota of the Fortymile
is a function of the number of dredges operating concurrently, the size of the dredges, the strategy and
effectiveness of their operators, and the rate and extent of re-colonization on the excavated dredge piles.
We compared conditions in the North Fork versus the South Fork of the Fortymile under the hypothesis that
the greater background mining activity (of all types) on the SF would result in reduced macroinvertebrate
abundance and diversity. We also expected that suction dredging would be relatively less harmful at already
impacted sites than at sites that were less disturbed. An increase in macroinvertebrate density was found in
the NF, relative to the SF, and this we attributed to the lower variability of benthic organic matter and
greater amounts of periphyton standing crop that occurred in the NF. We could discern no natural reason
for this difference and therefore attribute this result to the greater disturbance in the SF from all forms of
mining, historic and current.
The second component of this project is to examine the effects of recreational suction dredging on smaller
streams in Alaska. In 1997, sampling was conducted on a single site on Resurrection Creek, a designated
recreational mining stream on the Kenai Peninsula. In 1998, sampling was conducted on the Chatanika
River, known to be popular for recreational dredging. The Chatanika River was sampled at a location north
of Fairbanks. The results from Resurrection Creek indicated that there was no difference in the
macroinvertebrate community between the mining area and the locations downstream of the mining area,
in terms of macroinvertebrate density, taxa richness, EPT richness, or food resources. Results from the
Chatanika showed slight downstream decreases in macroinvertebrate density, but all other measures
remained similar to those of the reference area. In general, our results are in agreement with other studies
that have found only localized reductions in macroinvertebrate abundance in relation to small-scale suction
dredging.
Part I - Suction Dredging in the Fortymile River
Introduction
This report describes the results of research performed during 1997 and 1998 to determine the possible
impacts of commercial suction dredging on the water quality, benthic habitat, and biota of the Fortymile
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River, Alaska (hereafter, Fortymile). Also described in this report are the impacts by recreational dredging
on the Chatanika River and Resurrection Creek. This is the first study of its kind to describe the effects of
suction dredge mining on river ecosystems in Alaska.
In stream ecosystems, aquatic macroinvertebrates have become the primary assessment tool for resource
managers (see Barbour et al. 1996, Cairns and Pratt 1993). Several characteristics of aquatic
macroinvertebrates, as a group, have led to their general acceptance as reliable indicators of ecological
condition: (1) they are generally immobile (relative to fish), (2) they consist of a relatively large number of
species that, collectively, display a range of sensitivities and responses to various types of habitat
degradation, (3) they tend to be ubiquitous throughout streams and rivers, and (4) they are relatively easy
to sample and identify. For these reasons, our assessment of the effect of suction dredging on the
Fortymile, Chatanika, and Resurrection focused on macroinvertebrates. In addition to aquatic
macroinvertebrates, water chemistry, streambed geomorphology, algal (periphyton) standing crop, and
benthic organic matter (BOM) standing crop also were measured in relation to suction dredging for both
years. The latter two components form the food base for stream herbivores and detritivores and are vital to
the production and recovery of aquatic macroinvertebrates. Variations in the sampling method between
years are described in the Methods section.
Historically, gold mining occurred throughout the Fortymile basin and several types of operations are still
active, including placer mining, hydraulic mining, and suction dredging. Large scale placer mining also
occurs in some sections of the Chatanika River and historically in the lower reaches of Resurrection Creek.
Our research was limited to investigations on the effects of suction dredging. We addressed two general
topics: (1) the effect of relatively large (8-10 inch) commercial suction dredges on ecological conditions in
the Fortymile and (2) the general effect of smaller (2-6 inch) recreational suction dredges on benthic
habitat and biota in the Chatanika River and Resurrection Creek. Part I of this report presents the results
from the Fortymile; Part II describes results of small-scale mining within the recreational mining sites.
Suction dredging typically involves excavating the deeper, largely uninhabited sediments and depositing
them on top of the ecologically more important surface substrates. Sorting and re-deposition of substrata
moved through a dredge were expected to alter the streambed geomorphology and create "dredge piles"
downstream of the dredges. Our effort here was directed toward determining the size (height, width) of the
dredge piles, relative to the cross-sectional width of the river. This type of physical disturbance of benthic
substrata generally reduces periphyton standing crop, BOM, and macroinvertebrate density. Thus, substrata
moved through the dredge were expected to support less periphyton than substrata in undisturbed areas of
the river (see Peterson 1996). Abundance and diversity of macroinvertebrates also were expected to be
sharply reduced in dredged areas, as physical tumbling of substrata is known to kill and/or dislodge
associated organisms (see Resh et al. 1988 for review), in addition to reducing the available food base.
The impact of commercial suction dredging on benthic organisms was evaluated in 1997 on the South Fork
and the mainstem Fortymile River (Fig 1.). One site was also sampled in the North Fork near the confluence
of the North and South Forks. In addition to resampling the 1997 mainstem and South Fork dredge sites in
1998, we expanded our sampling to include one dredge site on the North Fork and two additional dredge
sites on the South Fork. We also sampled three reference sites unaffected by mining activity on the North
and South Forks, including the 1997 North Fork Confluence site. Overall, our goals for 1998 were (1) to
determine the potential for recolonization of the previous year's dredge spoils, (2) to expand the spatial
scale of our sampling by including sites that were dredged early (June), and late (September) in the
season, and in different geomorphic settings (inside and outside of a meander bend), (3) to sample
dredged sites in a less-disturbed portion of the basin (North Fork) than our other sites, and (4) to compare
impact and recovery potentials of dredge mining between more disturbed (South Fork), and less disturbed
(North Fork) streams in the same basin.
The research on recreational dredging was designed to assess the potential impacts on the aquatic
macroinvertebrate community in streams from geographically diverse locations and streams known to have
annually repeated, relatively, intense mining occur in the same location. Several potential sites were
examined but most proved to be unsuitable for study because of the absence of discrete areas of
concentrated suction dredging confounded by other disturbances. Resurrection Creek contains a section of
stream designated for recreational mining activity by the State Department of Fish and Game and the U.S.
Forest Service and is located on the Kenai Peninsula in Southcentral Alaska. The Chatanika River has no
such designation that we know of, however it appears that mining is restricted to a section of river near
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Milepost 60 on the Steese Highway. The Chatanika River site is known to receive a sizeable amount of
suction dredge activity throughout its available mining season.
Methods
Sampling Design - The majority of our work on the Fortymile in 1997 was conducted at a single site, with
an 8-inch suction dredge operated by an experienced miner (hereafter, Site 1). Site 1 was located
approximately 13 kilometers (8 miles) upstream of the Taylor Highway-Fortymile River Bridge
(approximately 1411 30' W, 651 17' N; Township 7 south, Range 32 east). Sampling was performed at fixed
transects above, within, and below the dredge location (Fig. 2). Work at this site occurred from 14 through
17 August 1997, under baseflow conditions. Less intensive sampling also was conducted above and below a
larger (10 inch) dredge located on the South Fork Fortymile also by a veteran miner (Site 2a), and near the
mouth of the North Fork Fortymile (NF, Site 4). Sampling at Site 2a and in the NF was performed from 17-
18 August 1997 and was restricted to recently dredged piles and un-dredged reference areas because the
dredge was not active at the time, due to elevated water levels and turbidity following an intense rainstorm
over an extensive part of the basin.
During 1998, we returned to both Site 1 and Site 2a to determine the degree to which the areas dredged in
1997 had recovered relative to the reference areas. At Site 1, the previous year's dredge piles were re-
sampled using the same design as in 1997. At Site 2a, the area that had been dredged in 1997 was re-
sampled and another location, of different mining history and geomorphic setting, was studied for the first
time (2b). During 1998, we also sampled a dredge site located on the NF Fortymile (Site 3) to increase the
spatial extent of the study and to determine if the NF and SF respond differentially to effects of suction
dredging. Also in 1998 the reference site near the mouth of the NF was resampled and a comparable
unmined site on the SF just upstream of the confluence was added for better evaluation of potential SF/NF
background differences.
The Before-After-Control-Impact (BACI) approach is a powerful and generally accepted sampling design for
detecting environmental impacts (e.g., Smith et al. 1993, Stewart-Oaten et al. 1986, Green 1979). For the
present study, a BACI design was used for water chemistry and turbidity sampling at Site 1. Water samples
were collected prior to and during dredge operation (Before and After) as well as upstream and downstream
of the dredge (Control and Impact). Single measurements' were made at each of ten transects. It was not
possible to employ a BACI design for periphyton and macroinvertebrate measurements because of the
logistic problems associated with using an actual dredge and the limited amount of time available for
sampling under baseflow conditions. Instead, samples at Site 1 were collected upstream and downstream of
the dredge while the dredge was in operation. Five macroinvertebrate and periphyton samples were
collected at each transect, except the 0 m, 5 m, and 10 m transects. Sampling the 0 m, 5 m, and 10 m
transects individually was not practical due to the narrow width of the dredge piles; collection of five
samples across their limited width was not possible. Therefore, ten macroinvertebrate and periphyton
samples were collected from the 0-10 m area to document conditions immediately below the dredge. At
Site 2a, sampling was limited to recent dredge piles located 25, 35, and 70 m below the moored dredge,
and a reference transect located 250 m upstream of the dredge. Although the dredge was not in operation
during sampling at Site 2a, it had been in operation during the preceding week. Finally, the samples from
the reference area at Site 2a were used with similarly collected samples from the mouth of the NF to
compare conditions in the two forks of the Fortymile River.
In 1998, five macroinvertebrate and periphyton samples were taken from the reference, mined, 20 m, and
40 m locations at Site 1 to determine the extent of recovery after one year. No mining occurred at Site 1
during the 1998 study period. At Site 2a, samples were taken from the reference, 35 m, and 70 m
transects. At Site 2b, slightly downstream of Site 2a, samples were taken from three locations that had
been dredged along the inside of a meander bend. Ten samples were taken from an "Upper" location that
had been dredged in late September 1997. Five samples were taken from two dredged areas slightly
downstream of the upper location that had been dredged within the preceding week. We sampled a single
dredge site on the NF that had been dredged with a 10 inch dredge within the previous 10 days of our
sampling. Samples were taken at locations that had been dredged, no attempt was made to document the
downstream extent of mining disturbance at this site because of inconsistent (patchy) dredge operations by
the Site 3 dredge operators. Ten samples were taken from a location not affected by mining in the NF, as
well as from each of three transects within the mined area. In addition to the dredged locations within the
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Fortymile basin, ten samples were taken from unmined locations in both the SF and NF near their junction
with the mainstem (Sites 4 and 6). A second NP location was sampled on request by the US Geological
Survey after an upwelling of groundwater containing arsenic and other heavy metals was located on the
North Fork and is described in detail below. Ten samples were taken from this location and were compared
to samples taken from upstream of the upwelling.
Field and Laboratory Methods - The methods used throughout this study are standard and widely accepted
techniques in stream ecology. Published reference sources provide detailed instructions regarding these
methods (Hauer and Lamberti 1996, APHA 1995, Cuffney et al. 1993, Porter et al. 1993, Platts et al. 1983).
These references often provide multiple methods for sampling a given variable. We selected the techniques
that were most applicable to our work on the Fortymile; specific details and modifications used on the
Fortymile are described below.
Turbidity, the inverse of water clarity, and specific conductance, a measure of the amount of total dissolved
mineral salts in the water, were measured on location with portable meters (Hach model 2100P and Orion
model 135, respectively) immediately after collection of the water samples. The meters were calibrated on
a regular basis, as indicated in the manufacturer's instructions. Water samples for alkalinity and hardness
were stored in insulated containers after collection to minimize chemical and biological activity in the water.
For analysis, the samples were sent to the Stream Ecology Center, Idaho State University. The alkalinity
and hardness of each sample was determined in the laboratory using standard titration methods (APHA
1995).
Samples for total filterable solids were filtered on location within 3 hours of collection. The filters containing
the samples were stored in insulated containers to minimize bacterial degradation of filtered organics. Upon
completion of the field sampling, the samples were sent for analysis to the Stream Ecology Center, Idaho
State University. These samples were analyzed by determining the amount of mass lost on combustion at
5501C for 3 hours. The amount of mass lost on combustion is equivalent to the organic mass of the sample
and is referred to as ash-free dry mass (AFDM). Standard procedures were used to determine the AFDM of
the samples (APHA 1995). Total settleable solids were measured on-site immediately after sample collector
using Imhoff cones; settleable solids were measured only while the dredge was in operation.
Water samples from the Fortymile River were collected for determination of heavy metal concentrations
using the "clean hands/dirty hands" procedure as prescribed by the US Environmental Protection Agency.
All materials (sample containers, filters, coolers, etc.) and protocols used in the collection of heavy metal
samples were provided by US EPA. Samples were sent for analysis to the US EPA laboratory in Manchester,
WA. In 1998, macro invertebrates were collected to examine the potential of these organisms to concentrate
heavy metals within their tissues. Macro invertebrates were collected from four locations: Alder Creek, Polly
Creek, and two locations on the NP Fortymile. Alder and Polly creeks are tributaries to the mainstem of the
Fortymile; Alder served as the reference site and Polly as a site that has been mined historically and
currently experiences some mining activity. On the NF Fortymile, the USGS has identified an area of
upwelling groundwater that potentially is a source for dissolved heavy metals in that river. One of the NF
Fortymile sites from which macroinvertebrates were collected was located above this possible heavy metal
source, the other downstream of it. After collection, the invertebrates were immediately frozen and kept
frozen until analysis. Analysis of the metal concentrations within the invertebrate tissues was conducted by
James Crock at the USGS, Mineral Resources Program, Denver. To obtain a sufficient mass of tissue for
analysis, all individuals from a site were combined; thus the results are based on a single measurement per
site. The invertebrates were dried, pulverized, and weighed. The material was then transferred to a TeflonT"
vessel and digested in 10 mL of concentrated nitric acid. One mL of the solution was diluted to 10 mL and
analyzed using the USGS standard ICP-MS method. Mercury was determined using a cold vapor-atomic
fluorescence spectrometry on a separate 1 mL aliquot diluted to 10 mL in sodium dichromate/nitric acid
(James Crock, personal communication).
Description of streambed morphology was accomplished by developing cross-sectional profiles (see Platts et
al. 1983) of the river at the transects described above (Fig. 2). Distance out from a fixed location on the
bank was measured along a (Kevlar) cable stretched taut across the river. At numerous points across the
width of the river, the distance from the cable to the water surface and the total water depth were
measured.
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All macroinvertebrate sampling was done with a Portable Invertebrate Box (PIB) sampler that was modified
for use in water deeper than the height of the sampler. The PIB sampler encompassed 0.093 m2 of
streambed (the sampler was approximately 30 cm on a side). The sampler was placed into position on the
streambed and held in place by one operator while the second operator disturbed the substrata enclosed by
the sampler to dislodge the organisms. A removable 250p.m mesh net was attached to the downstream
end of the sampler to collect the dislodged organisms. Although designed to be used in deep water, the
current velocity of the Fortymile precluded use of the sampler at most deep-water locations, particularly
those in the center of the river. At some deep-water locations, SCUBA techniques were used to collect the
samples; SCUBA was required for collection of approximately 5% of the samples collected within the
sediment plume. In general, all macro invertebrate samples were collected from near-shore habitats,
approximately 2-30 meters from the bank. This is the same distance from the bank in which the dredge
was operating.
Following collection, each sample was placed into a labeled plastic bag (Whirl-pak brand) to which
approximately 10-15 ml of concentrated formalin was added to preserve the organisms. In the laboratory,
the contents of each macroinvertebrate sample were spread-out in a white sorting tray and all organisms
removed. The sorting was accomplished with the aid of a dissecting microscope of lOX magnification. The
organisms were then identified to the lowest feasible taxonomic level, usually genus, using published
taxonomic references, primarily Merritt and Cummins (1996), Wiggins (1996), and Stewart and Stark
(1993). A reference collection was established and voucher specimens are located in the Stream Ecology
Center, Pocatello at Idaho State University.
Periphyton samples were collected from individual rocks located just upstream of each macroinvertebrate
sample. Processing was done immediately after collection of the rock and followed the procedures of
Robinson and Minshall (1986). Briefly, the process involved removing all material within an enclosed area
(3.14 cm2) from the rock surface. The removed material was then suctioned onto a pre-fired, glass
microfiber filter (Whatman GF/F). Filters were frozen with liquid nitrogen in a modified dewar flask (Taylor-
Wharton model 3DS) and sent to the Stream Ecology Center, Idaho State University for processing.
Periphyton samples were extracted with reagent grade methanol (Holm-Hansen and Riemann 1978) and
the 1997 chlorophyll-a content was determined with a spectrophotometer (Gilford Instruments model
2600). The 1998 chlorophyll-a samples were analyzed using a fluorometer in order to detect very low
concentrations. Following centrifugation, approximately 3 ml of the sample was removed and used in the
chlorophyll-a determination, the remaining material was used for measuring the AFDM of the sample as
described above under total filterable solids.
Results
Water Chemistry and Clarity
At Site 1, dredge operation had no discernable effect on alkalinity, hardness, or specific conductance in the
Fortymile (Fig. 3). Alkalinity ranged from <20 to >50 mg CaC03/L, regardless of whether or not the dredge
was operating. Hardness ranged from approximately 80 to 115 mg CaC03/L. Both alkalinity and hardness
displayed a large amount of variability in the immediate vicinity of the dredge whether or not the dredge
was operating. Values of alkalinity and hardness measured at 320 m below the dredge were similar during
operation of the dredge to values measured when the dredge was not in use (Fig. 3). Specific conductance
showed only slight spatial and temporal variation during our sampling. Values ranged from 131 to 135
pS/cm, with a small decrease immediately downstream of the dredge, when in operation (Fig. 3). Turbidity
and total filterable solids (TFS) both displayed an increase below the dredge (Fig. 4). During operation of
the dredge, turbidity increased from values around 1 NTU upstream of the dredge to values of
approximately 25 NTU immediately downstream of the dredge. The elevated turbidity declined rapidly
downstream and by 160 m ( 525 ft) turbidity had returned to values measured upstream of the dredge. No
such increase in turbidity was recorded when the dredge was not in operation. TFS showed a pattern similar
to that of turbidity, increasing from 3 mg AFDM/L upstream of the dredge to 46 mg AFDM/L immediately
downstream of the dredge (Fig. 4). As with turbidity, TFS did not display an increase downstream of the
dredge when the dredge was not operating. Regardless of whether or not the dredge was operating, a
longitudinal increase in TFS was measured from 80 m to 320 m downstream of the dredge. At 160 m
downstream of the dredge, values of TFS were 28 and 23 mg AFDM/L during operation and non-operation,
respectively. Total settleable solids showed a pattern very similar to that observed for TFS (Fig. 5).
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During operation of the dredge, specific conductance and turbidity were measured across the width of the
Fortymile at 0, 5, 10, 20, and 320 m downstream of the dredge to identify the proportion of the river width
affected by the dredge plume. Specific conductance was unaffected by the dredge plume which was located
along the right bank, but did decrease near the left bank (Fig. 6). This decrease was most likely due to
groundwater and/or a small tributary that joined the Fortymile on the left bank just upstream of the study
area.
Unlike specific conductance, cross-sectional measurements of turbidity from within the dredge plume
showed a large increase, relative to areas outside the plume (Fig. 7). However, at 320 m downstream of
the dredge, cross-sectional variation in turbidity was quite low, ranging from 1.2 to 2.5 NTU. During this
sampling, the dredge was operating in close proximity to the right bank. Under these conditions, the plume
tended to remain near the right bank and did not extend to the center of the river. In terms of turbidity,
approximately 7% of the river width was affected by the dredge plume for a distance of less than 320 m.
Heavy Metals
For the unfiltered samples, two metals, copper and zinc, showed distinct increases downstream of the
dredge (Fig. 8). Total copper increased approximately 5-fold and zinc approximately 9-fold at the transect
immediately downstream of the dredge, relative to the concentrations measured upstream of the dredge.
For both metals, the concentrations declined to near upstream values by 80 m downstream of the dredge.
The pattern observed for total copper and zinc concentration is similar to that for turbidity and TFS (see Fig.
4), suggesting that the metals were in particulate form, or associated with other sediment particles. The
results of sampling for dissolved heavy metals area are shown in Table 1. Zinc, arsenic, and copper
displayed an average value downstream of the dredge that was greater than the average value measured
upstream of the dredge (note that samples sizes are low, particularly upstream of the dredge). Copper
displayed the greatest change, increasing by approximately 3-fold downstream of the dredge. Dissolved
lead concentrations did not appear to be affected by operation of the dredge. Values of dissolved mercury
actually were greater upstream of the dredge, suggesting that any effect of the dredge was likely within the
range of natural variation. (The operator reported observing deposits of liquid mercury within the sediments
he was working.) For both dissolved and total concentrations, budgetary limitations precluded multiple
sampling across either space or time, thus the results of heavy metal sampling are only indicative of likely
conditions.
Due to the low densities of macroinvertebrates in the dredge plume (and in the Fortymile in general) and
the short exposure times, no macroinvertebrates were collected for heavy metal tissue analysis
downstream of the suction dredge. However, results from the 1998 analysis of macroinvertebrate tissues
suggest that these organisms are capable of concentrating heavy metals at least under conditions of
chronic exposure. Although the data are preliminary in nature, several metals showed substantially greater
concentration in the invertebrates from Polly Creek (mined) than from Alder Creek (reference), including
mercury, zinc, molybdenum, and arsenic (Table 2). Other metals, such as copper and nickel, did not exhibit
substantial differences between the two sites. The upwelling area identified by the USGS as a potential
source of metals in the NF Fortymile did not appear to be influencing metal concentrations in
macroinvertebrates. For the metals listed above, nickel was the only metal that showed a substantial
increase (Table 2).
Channel Morphology
Site 1- Cross-sectional profiles were mapped to quantify the extent of the dredge piles relative to the width
of the river. At Site 1 only the pile created most recently, 0 m downstream of the dredge, was visible with
our profile mapping (Fig. 9). At the transects 5 and 20 m downstream of the dredge the piles were visually
obvious due to the light color of the excavated material compared to undisturbed riverbed. However, the
piles did not appear as distinct "mounds" in the measurements made at these transects. One year after
active dredging occurred, the distinct mounds seen in Figure 8 at the 0 m transect were no longer
apparent. There was no discernable dredge pile at the 5 and 20 m areas. Figure 9 is based on detailed
mapping along the right bank of the river and is drawn to scale to represent the conditions within the
streambed relative to the depth of the river in that area. There is a large width:depth ratio for Site 1 as
indicated by Figure 10. Discernable dredging activity can be seen within the first 5 m from the right bank.
The area that this particular dredge operation affected was about 6% the width of the river.
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Site 2a- In August 1997 partial cross-sectional profiles were measured every 5 meters, beginning slightly
downstream of dredging activity and continuing for 110 meters, to map a series of dredge piles along the
right bank of the South Fork of the Fortymile (Appendix A). In July 1998 three transects were re-measured
to map the change in location of the dredge piles (Fig. 1). The dredge pile at 30 m shows a shift towards
the center of the stream, though the overall size remained essentially the same after one year. A profile of
the 40 m transect produced similar results. Remaining partial cross-sectional profiles are presented in
Appendix A.
Site 2b- In July 1998 a second site on the South Fork was included in our sampling to determine if there
are spatial differences in dredging effects on biota. Cross sectional profiles were measured. Full cross-
sectional profiles were completed for the "upper" pile in 1998 which had been dredged in September of
1997 (Fig. 12) and partial cross-sections were measured for the upper, middle, and lower locations (Figs.
13 and 14). Easily discernable dredge piles were observed and measured between 0, 5, and 10 m below a
reference transect at the upper location for Site 2b. Partial cross-sectional profiles also were measured to
determine the longitudinal extent of the upper dredge pile (Fig 13). According to our measurements, the
upper dredge pile tapered off at about 35 m. Profiles for the middle and lower dredge areas show another
dredge pile beginning between 80 and 100 m. The lower dredge pile begins at about 130 m and continues
slightly past 140 m (Fig 14). The middle and lower dredge areas were mined about 7 days prior to our
sampling at Site 2b.
Site 3- Cross-sectional profiles also were measured at Site 3 in the North Fork. Entire width profiles were
measured every 20 m along this reach (Fig. 15) and partial profiles were measured at various distances
between each full profile (Fig. 16). Dredging was active at the 0 m and 10 m locations and between the 40
and 60 m locations. There is a large width:depth ratio for Site 3. Figure 13 shows the size of the dredge
piles relative to the entire width of the river for Site 3. The full width profile measured for Site 3 shows
distinguishable channel forms where mining activity had occurred within 10 days of our sampling at 20 m,
60 m, and 80 m though the 80 m location may simply be due to natural bed forms. The lack of obvious
dredge piles at the 0 m and 40 m locations are most likely because the dredge pile began slightly upstream
of these locations. Dredge piles accounted for approximately 15% of the total channel width at Site 3.
The partial profiles show very distinct dredge piles 5 m downstream of mining activity which can be seen
nearly 4 m from the right bank. 10 m downstream another relatively distinguishable streambed "rise" is
discernable between 4 and 6 m from the right bank. There is no discernable effect on the streambed 15 m
downstream of mining activity according to these profiles.
Periphyton Standing Crop
At Site 1, 1997 periphyton AFDM was greatest at the transect upstream of the suction dredge, with a mean
value of 1.8 mg AFDM / cm2 (Fig. 17). Periphyton standing crop was reduced by approximately 2-4 fold at
the transects downstream of the dredge. The lowest value, >0.5 mg AFDM / cm2, occurred in the first 10 m
immediately below the dredge. Unlike other variables, periphyton standing crop did not appear to recover
at subsequent transects downstream of the dredge. At the 320 m transect, for example, AFDM was only
50% of the value measured upstream of the dredge. Chlorophyll-a concentrations are reduced to
unmeasurable values within the areas dredged and 20 m below the operating dredge. Measured
chlorophyll-a concentrations follow the results of periphyton standing crop biomass downstream of the
operating dredge. After one year, chlorophyll-a concentrations and periphyton standing crop biomass in the
mined area had returned to values near those from the unmined reference location, indicating that
periphyton is unaffected by dredging the previous year at this location (Fig 18).
Both periphyton standing crop and chlorophyll-a at Site 2a showed little response to dredging in comparison
to the upstream reference location in 1997. In 1998, mean chlorophyll-a concentrations were nearly
identical at the reference location to those values in 1997; however, mean chlorophyll-a concentrations
were greater at each of the dredged locations in 1998 than in 1997 (Fig 19). Periphyton standing crop in
1998 also increased 2-4 fold in the reference and 25 m locations and increased slightly less in the 70 m and
100 m locations after one year (Fig 19).
At Site 2b, periphyton standing crop biomass averaged between 3 and 4 mg/cm2 for all locations regardless
of the year in which they were dredged. However, mean chlorophyll-a was 2.5 times greater in the "Upper"
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location, which had been dredged late in the previous year, than either of the other two nearby locations
that had been dredged in 1998. The Upper location was dredged late in the 1997 mining season but
sampled only during 1998. The greater amount of chlorophyll-a in the upper location, compared to the
other two (1998) dredge piles is most likely due to the additional time of recovery (Fig. 20).
Comparisons between the NF and SF Fortymile were conducted to document differences in background
conditions and the potential for recovery of mined areas in two tributaries with different mining pressures
within the same basin. Mean periphyton biomass was three times greater in the NF site (Site 4) than in the
SF site (Site 6) in 1997. Mean chlorophyll-a concentrations were 4 times greater in the NF than, in the SF
for the same year (Fig 21).
Aquatic Macroin vertebrates
Site 1- The short-term influence of the suction dredge on macroinvertebrates appeared to be limited to the
first 20-40 m downstream of the dredge. Two locations were examined upstream of the dredge at Site 1,
the first was approximately 80 m upstream and the second approximately 200 m upstream. In terms of
water velocity and substrate characteristics, the -200 m site was considerably more similar to the habitat
downstream of the dredge than was the -80 m site. For this reason, only the -200 m transect was used as
the reference for Site 1.
The abundance of macroinvertebrates at Site 1 was low, relative to large rivers in other parts of North
America (e.g., Royer and Minshall 1996). A mean of 270 individuals per m2 was collected at the reference
site; approximately 370 individuals per m2 were found at the site 160 m downstream of the dredge (Fig.
22). Diversity averaged 6-7 taxa per sample at the reference site and ranged from 1 to 7 taxa per sample
at the sites downstream of the dredge. Taxa within the orders of Ephemeroptera (mayfly), Plecoptera
(stonefly), and Trichoptera (caddisfly) are considered sensitive to habitat degradation and are used
commonly in aquatic bioassessment. The mean number of EPT taxa was 5 per sample at the reference site
and ranged from <1 to 5 per sample at the sites downstream of the dredge.
The abundance and diversity of macroinvertebrates at Site 1 was greatly reduced in the first 10 m below
the dredge, relative to the reference site. Immediately below the dredge (0-10 m) macroinvertebrate
abundance was reduced by 97%, number of taxa by 88%, and number of EPT taxa by 92%, relative to the
site 200 m upstream of the dredge. The abundance and diversity of macroinvertebrates returned to values
seen at the reference site by 80 to 160 m downstream of the dredge.
The relative abundance of all taxa collected from the Site 1 in 1997 are presented by transect in Table 3.
The order Trichoptera was the most abundant, in terms of richness, with seven genera represented. Five
genera of Ephemeroptera and two genera of Plecoptera were collected. Two families of Diptera were found,
Simuliidae (blackflies) and Chironomidae (midges). Other groups included: one genus of Coleoptera
(beetles), Acarina (water mites), Collembolla (springtails), Oligochatea (aquatic earthworms), and
Ostracoda. For all transects, 50% or greater of all taxa were members of the Chironomidae and the
Ephemeroptera.
The sampling conducted in 1998 indicated substantial recovery at Site 1 from the dredging that occurred in
1997, in terms of macro invertebrate diversity. Diversity was notably reduced downstream of the dredge in
1997 (see above) but in 1998 the difference in diversity among the four transects was minimal (Fig. 23).
For example, at the location 20 m downstream of the dredge macroinvertebrate diversity was
approximately 6 taxa in 1997 but 17 taxa in 1998. A similar increase in the number of taxa was observed at
all Site 1 transects that were sampled in both 1997 and 1998. Macroinvertebrate density and the number of
EPT taxa also increased after one year (Fig. 24).
Site 2a- Sampling in 1997 revealed patterns at Site 2a similar to those observed at Site 1.
Macroinvertebrate density at the reference transect was approximately 200 individuals per m2 (Fig. 25). At
the transect 25 m downstream of the dredge, density decreased to approximately 20 individuals per m2
and then increased to about 100 individuals per m2 at the transect 70 m downstream of the dredge. The
number of taxa at the reference transects was equal for Site 1 and Site 2a and showed a similar
downstream pattern at both sites. The number of EPT taxa, however, was considerably less at Site 2a in
1997, although the downstream pattern was the same as that for Site 1. Recovery of macroinvertebrate
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diversity at Site 2a was nearly complete one year after dredging with approximately 20 taxa at each of the
transects (Fig. 26). One year after dredging with a 10 inch dredge at Site 2a, macroinvertebrate density,
richness, and number of EPT taxa also had recovered to pre-mining conditions (Fig. 27).
Site 2b- A second site was established on the South Fork of the Fortymile River in 1998 to evaluate the
effects of dredging on a nearby site with different water flow and possibly substrate composition. This site
was on the inside bank of a meander bend, about 800 m downstream of Site 2a. Site 2b was also used to
evaluate the effects of dredging late in the fall on macroinvertebrate composition. In Figures 28 and 29,
locations labeled "Upper" represent an area dredged with a 10-inch dredge in late September 1997.
Locations labeled "Middle" and "Lower" represent adjacent areas mined within a week of our sampling in
July 1998. Comparing Site 2a results with the Upper location of Site 2b revealed that there were in fact
differences in macro invertebrate density between the Upper site of Site 2b and the reference area of Site
2a. Mean macroinvertebrate density at the reference location of Site 2a was 26% of the "Upper" location of
Site 2b, 40% of the "Middle" and nearly 30% of the "Lower" locations (Fig 28A). The number of EPT taxa
per sample present in the Site 2a reference location were 74% that of the "Upper" location of Site 2b (Fig
29A). Likewise, the number of Diptera present in each sample from Site 2a were 72% those present at Site
2b (Fig. 29B) Diptera comprised between 40 and 80% of the macroinvertebrates per sample at all of our SF
sites.
Site 3- We sampled a single dredge site on the North Fork in which a 10-inch dredge was operated by an
experienced miner and was actively dredged within 10 days prior to our sampling. This site consisted of
three dredged areas, one beginning at the head of our study reach (TO), the second stretching the length
between 10 and 20 m from the TO location (T10), and the third encompassing the distance between 40 and
60 m (T40) from the TO location. The mined areas at 0 m, 10 m, and 40 m were compared to a reference
location in an unmined area of similar substrate type and water velocity. We were not able to determine the
distance downstream affected by dredging because of inconsistent dredge operations by the North Fork
miners which were caused by relatively high flows over the duration of our sampling. The study reach
chosen here allowed us to determine the short term recovery (> 10 days) of these dredged areas in the
North Fork. Our results suggest that all measures except macroinvertebrate density appeared to fully
recover within 10 days since dredging. Macroinvertebrate density at the reference location averaged about
1600 organisms per m2 while densities within the mined areas averaged between 1200 and 1400
organisms/m2 (Fig. 30A). Macroinvertebrate taxa ranged from 10 to 12 per sample for all locations (Fig.
30B). Mean numbers of EPT taxa ranged from 5 to 6 per sample (Fig. 30C). Diptera, which comprised the
majority of the macroinvertebrate community at all of the sites sampled, ranged from 60 to 80% in the NF
sites (Fig. 30D).
North Fork/South Fork Comparison - Comparisons between the North Fork and South Fork were made to
determine if the South Fork macroinvertebrate populations were depauperate due to degraded water quality
from increased mining activity on the South Fork itself and some of its major tributaries. In 1998 we
sampled a different reference location on the South Fork (Site 6, see Fig. 1) that was nearly 500 m
upstream of its confluence with the North Fork and compared this data with those from an unimpacted
reference site several kilometers upstream on the North Fork (Site 5). We also compared this North Fork
reference site to a location downstream of an upwelling of heavy metals noted by the USGS near the
confluence of the North and South Forks (Site 4).
The upwelling of heavy metals between Sites 4 and 5 appears to have little effect on macroinvertebrate
populations in the North Fork. The number of taxa, number of EPT taxa, and overall relative abundance of
Diptera are nearly identical for both Sites 4 and 5. Macroinvertebrate density was nearly 2500/m2
downstream of the upwelling and nearly 1500/m2 upstream (Fig 31A). The number of taxa per sample at
all locations ranged from 11 to 12 (Fig 31B). The number of EPT taxa ranged from 5 at the NF and SF
reference areas, to 6 at the NF confluence area (Fig 31C). Diptera comprised 60 to 80 % of the
macroinvertebrates at all locations (Fig 31D).
Although we did not sample the South Fork confluence site in 1997, there may be some degree of yearly
variation in macroinvertebrate populations in the South Fork as seen from comparison of reference
conditions from Site 2a (see Fig. 26). In the North Fork however, there appears to be less yearly variation
in macroinvertebrate populations in the years that we sampled. Even though taxa richness was similar at
the NF and 2a sites in both years, the relative dominance of taxa differed among the sites (Fig. 32). There
was a greater difference in the taxa abundance of some taxa between years at the SF reference location
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whereas there is almost no change in the relative dominance of taxa in the NF site. The difference is seen in
the shape of the curves. Table 4 shows that the Chironomidae (order Diptera) comprised over 75% of all
the macroinvertebrates present in our samples at Site 4 in 1997 and 82% in 1998. Baetis comprised 0.5%
in 1998, and 5.5% in 1997. In the SF Diptera comprised about 34% of the macroinvertebrates in 1997 and
about 35% in 1998. However, Oligochaeta (Annelida) comprised 32% of the macroinvertebrates in 1998
and only 8% in a 1997. Baetis, a mayfly, comprised 1.3% of the macroinvertebrates in 1998 and 5% in
1997.
Benthic Organic Matter
Benthic organic matter (BOM) is a primary source of carbon and energy for organisms that live on and
within the substrate of the river. In general, the amount of BOM found in the Fortymile was lower than
values from many streams in the contiguous United States (see Minshall et al 1982), but are similar to
other studies from the interior arctic and subarctic Alaska region (for example, see Miller and Stout 1989).
Site 1- In 1998, mean amounts of BOM within the mined area were slightly lower than those found at the
reference and downstream (20, 40 m) areas. BOM at the 20 m location is also much more spatially variable
than at the other locations (Fig. 33). This increased patchiness may be a result of the downstream
redistribution of BOM from upstream dredged areas.
BOM concentrations at Site 2a in 1997 were similar between reference and mined locations, averaging 5 g
per m2 at the reference location and 9 and 11 g per m2 at the 35 m and 70 m locations, respectively (Fig.
34). Mean amounts of BOM in 1997 at the reference area was 15% that of 1998. In 1998, mean BOM at
Site 2a ranged from an average of 33 g per m2 at the reference area to 25 and 37 g per m2 at the 35 m
and 70 m areas, respectively. BOM at Site 2b ranged from 23 g per m2 at the locations mined in 1998
(Middle and Lower areas) and averaged 53 g per m2 at the location mined in the late fall of 1997 (Upper
area). These values were similar to those from 1997 for Site 2a, indicating a yearly variation in BOM of
between 15 and 30%. BOM from Site 3 averaged between 6 and 7 g per m2, and showed little difference in
average amounts between locations (Fig. 35). However, the coefficients of variation in the mined locations
showed considerable variability, particularly at the 35 m location.
Mean amounts of BOM in both the NF and the SF confluence locations show considerable differences. At the
SF confluence site (Site 6), BOM was more spatially variable and averaged more than twice the amount
found at the NF confluence site (Site 4, Fig. 36).
Discussion
The primary effect of suction dredging on water chemistry of the Fortymile River, as detected at Site 1, was
increased turbidity, total filterable solids (TFS), and copper and zinc concentrations downstream of the
dredge. Turbidity and TFS were substantially elevated downstream of the dredge and the plume of
sediment-laden water created by the dredge was visually obvious. But, although the plume was visually
dramatic it was spatially confined to within 160 m (= 525 ft.) of the dredge and was restricted to the
portion of those days that the dredge was operating. Furthermore, the effect of the plume was limited to
approximately 7% of the width of the river. The results from this sampling revealed a relatively intense, but
very localized, decline in water clarity during the time the dredge was operating. Wanty et al. (1997)
reported turbidity values of 19 NTU 30.5 m (100 ft) downstream of a 10 inch dredge located below Wilson
Creek on the North Fork Fortymile River. Values returned to near background levels (3.7 NTU) within the
next 30.5 m but remained slightly above background levels (2.2 - 2.3 NTU) as far as 150 m downstream
(furthest sampling transect). Turbidity values downstream of an 8-inch dredge operating in the same
vicinity were lower because less sediment was being disturbed and the sediments were coarser and hence
settled more rapidly. The 19 NTU at 30.5 m is comparable to the value we found at 20 m at Site 1.
Wanty et al. (1997) examined dissolved metal concentrations 60.8 m (200 ft) downstream of a 10-inch and
an 8-inch dredge and found no difference between the sides and center of the dredge plume. In our study,
dissolved metals displayed no clear pattern in relation to the dredge suggesting the increased
concentrations of total copper and total zinc at Site 1 were likely a result of metals associated with the
sediments excavated by the dredge. As the metal-laden sediments were transported downstream and
deposited on the riverbed, total copper and zinc concentrations declined. By 80 m downstream of the
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dredge, copper and zinc concentrations were similar to those measured upstream of the dredge (see Fig.
8). These results suggest the need for examining heavy metal accumulation on the riverbed, rather than
instantaneous measures of heavy metal concentrations in the water column. The examination of heavy
metal concentrations in aquatic macroinvertebrates indicated that at some locations, such as Polly Creek,
the chronic effects of mining may be reflected in the physiological condition of the biota. However, the
degree to which metals within the tissues of the macroinvertebrates may influence life-history or other
biological traits is unknown.
Discussions with local miners indicated that the amount of material in the plume is, in part, a function of
the type of sediment that is being excavated from the riverbed. Thus, the impact of suction dredging on
water clarity and heavy metal concentrations may be greater or lesser than that reported here, depending
on the type of material being excavated. In general, the observed decrease in water clarity was unlikely to
have altered ecosystem function in that area of the Fortymile. However, the increased sediment load and
rapid reduction in light could cause aquatic organisms to drift (Allan 1995:221-237, Wiley and Kohler
1984), resulting in reduced macroinvertebrate abundance and/or delayed re-colonization of dredge piles.
The effect of suction dredging on the abundance of drifting macroinvertebrates was not addressed in the
present study, but drifting is likely an important mechanism in the interaction between macroinvertebrate
abundance and suction dredging. In particular, organisms capable of drifting may be displaced, but not
killed, by the dredging activities. Those organisms that are entrained by the dredge will not necessarily be
killed. For example, Griffith and Andrews (1981) examined >3,600 organisms and reported less than 1%
mortality for macroinvertebrates entrained through a 3-inch suction dredge.
The cross-sectional profiles indicate the impact of the dredge piles relative to the width of the river was
small (see Fig. 10). Assuming widths of 2 m for the dredge pile and 80 m for the river, the dredge pile
would represent 2.5% of the river width. Our results show that in all four of the dredge sites studied, there
were substantial changes to the bed morphology where dredging had occurred, but there was no
discernable change toward the center of the river. There also did not appear to be any downstream
influence on bed morphology by dredged sediments, indicating that dredging strongly influenced
immediately adjacent substrates but had little effect beyond, either laterally or downstream of the dredged
area. Though no measurements of substrate composition were made directly in the Fortymile, it seems
likely that suction dredging has little effect on the size and distribution of bed sediments. Local miners claim
that much of the Fortymile River system has been mined in recent history and though this is an
unsubstantiated claim, it appears reasonable as we observed no striking differences between sediment
compositions within mined areas and those in reference areas particularly in the amount of deposited fines.
We did observe that at Site 1, downstream gravels were covered with a fine sediment within the plume
caused by the dredge. Given the shallow depth of bedrock and the intense scouring action by ice-flows and
spring runoff, it is likely that sediments of all sizes may be well mixed and that fine sediments do not
accumulate at the bed surface.
After one year discernable dredge piles remained at one of the two sites studied in both years, though
reduced in size and in the South Fork site, shifting toward the stream's center. Thomas (1985) studied
suction dredging in a stream in Montana and reported that spring flows eliminated dredge piles created
along the stream margin. Likewise, Somer and Hassler (1992) examined the effect of suction dredging in
two northern California streams and observed that dredge piles existed only seasonally and did not persist
beyond springtime high-flows. Based on our observations and results, it appears likely that the dredge piles
at the locations we examined will remain in place no longer than 1 to 3 years. In many cases the stream
channel will return to its pre-dredge condition in a year as a result of river freezing and the succeeding ice-
action and springtime flows that accompany snow-melt in the Fortymile drainage.
The abundance and diversity of aquatic macroinvertebrates at a given site are closely related to the size,
stability, and surface complexity of the substrata at that site (e.g., Minshall 1984, Hart 1978). In addition,
the magnitude of impact a particular disturbance has on a macroinvertebrate community may be mediated
by substrate size; small rocks are more easily tumbled (i.e., disturbed) than are larger rocks (Gurtz and
Wallace 1984). Thus, the effect that suction dredging has on the macroinvertebrate community of the
Fortymile depends on the characteristics of the substrata being disturbed. The rate at which dredge piles
are re-colonized also will depend on stability of the individual substratum. A detailed study requiring a
longer period of time than was available would be required to accurately determine the rate at which
macroinvertebrates re-colonized dredged areas. Studies of smaller scale dredging impacts have shown
complete recolonization within 30 days of the cessation of mining activity. Given the northern extent of the
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Fortymile region, the harsh climate and short time available for production and recolonization, the
depauperate macroinvertebrate structure, and the likely low quality and quantity of available food resources
typical of sub-arctic rivers, recolonization would likely be extended beyond 30 days. It also is possible that
the initially low abundance and diversity of macroinvertebrate taxa in the Fortymile would cause rapid
recolonization due to the low numbers of organisms required to call an area "substantially recovered".
Without detailed recolonization studies for longer periods of time, it is difficult to "guess" at potential times
of recovery.
As with water clarity, the effect of suction dredging on macroinvertebrate abundance and diversity at the
locations we examined was confined spatially to a relatively small area downstream of the dredge. Other
researchers also have documented the localized nature of suction-dredge effects (Somer and Hassler 1992,
Harvey 1986, Thomas 1985), although each of these studies was conducted using smaller, recreational
dredges. In the present study, both abundance and diversity were notably reduced for 10 m downstream of
the dredge at Site 1. By 80 m below the dredge, however, abundance and diversity appeared unaffected by
the dredge plume. Site 2a displayed a similar pattern, although the sampling was more spatially limited.
The short-term, downstream impact of suction dredging on macroinvertebrates probably was limited to the
same area in which the dredge plume was visible. Therefore, the percent of the riverbed being affected by
the dredge was small: approximately 7% of the width for <80 m downstream. The cumulative effect of
suction dredging on the biota of the Fortymile cannot yet be assessed fully, but likely will depend on the
number of dredges operating concurrently and the distance between them, the size of the dredges, the
strategy of the dredge operators, and the extent of re-colonization that occurs on the excavated dredge
piles. Clearly, the effect of suction dredging will not be the same for all locations in the Fortymile and/or
sizes of dredge.
The results from 1998 indicate that substantial recovery of the macroinvertebrate community occurs within
one year after suction dredging. At both Site 1 and Site 2a, the transects dredged in 1997 showed, in 1998,
taxa abundance curves very similar to the reference transects (see Figures 23 and 26). Although suction
dredging is a very intense, local disturbance to benthic organisms. the biological and chemical effects of
suction dredging do not appear to extend for more than a year. However, conditions at these two sites after
two years and at sites 2b and 3 after one year could not be determined prior to the termination of the
project.
The comparison of conditions in the North Fork versus the South Fork suggests that macroinvertebrate
density in this river system may be a function of annual variation in food resources and physical conditions,
especially flow and suspended sediment (likely caused by additional mining activity in the SF tributaries).
Results from 1997 suggested that greater food abundance (e.g., periphyton and BOM) in the NF
corresponded to an approximately 5-fold greater density of macroinvertebrates. These comparisons were
made under the assumption that the reference location at Site 2a was representative of the South Fork
conditions. However, our 1998 comparison of the North and South Forks, using an undredged site in the SF
nearest to the confluence of the two streams (Site 6) and that we believe is more representative of
conditions in the tributary, showed no clear difference in biotic conditions between the two sites. The results
suggest that conditions may vary markedly among locations and years and suggest that in addition to
differences in food resources differences in physical conditions may be important. We suggest that other
mining activities within the basin, primarily those in the South Fork tributaries may be important causes of
decreased biotic integrity in some years and locations. However, suction dredge mining clearly reduces
macroinvertebrate densities, diversity, BOM, and periphyton immediately below dredge activity regardless
of the background conditions, though these effects are local and short lived.
Part II - Recreational Dredging in Resurrection Creek and the Chatanika River
Introduction
Recreational gold mining is a popular activity throughout much of Alaska and suction dredging is a common
method used in recreational mining. Recreational dredges are smaller than those examined on the
Fortymile and typically have intake lines of 2-6 inches in diameter. Despite the relatively small size of the
dredges, streams that are popular with hobbyists may experience a more intensive mining disturbance than
do larger rivers such as the Fortymile because of the concentrated and repetitive nature of the mining in
these areas. Part II of this report describes the results of our research into the effects of recreational
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suction dredging in several Alaskan streams.
Methods
Page 14 of 17
This research was conducted on Resurrection Creek located on the Kenai Peninsula in 1997 and on the
Chatanika River, located along the Steese Highway north of Fairbanks, in 1998. Resurrection Creek is
designated as a recreational mining site by the State of Alaska and the U.S. Forest Service and is open to
recreational dredging from about May 15 through July 15 of each year. The Chatanika River is not officially
designated for mining, but is a popular recreational site with few accessible areas that are open to mining
during approximately the same time period.
Our sampling on Resurrection was conducted on 22 August 1997; approximately 5 weeks after recreational
dredging in the Resurrection Creek had ended for the year. The general design was similar to that described
above for sampling on the Fortymile. Four locations were sampled: (1) within the reach of stream that
suction dredging is permitted, (2) approximately 500 m upstream of the dredged area, (3) approximately
35 m downstream of the dredged area, and (4) an area >500 m downstream of the dredged area. In each
of these locations, five macroinvertebrate samples and three periphyton samples were collected. Water
samples were collected at the location within the dredged area, but as active dredging was not occurring,
these samples are indicative of conditions in the stream as a whole. All samples were collected, preserved,
and processed as described above for samples from the Fortymile River.
Sampling on the Chatanika River occurred during July 1 and 2, 1998 approximately two weeks prior to the
end of the mining season for that region. Because there was no designated downstream mining boundary
as there had been for Resurrection Creek, a slightly different sampling regime was used. Samples were
taken at approximate distances downstream of last distinguishable active mining location within the river.
Transects at "Mined", 50, 100, 150, 300 and 500 m were sampled on two different days. However, an
intense rain within the Chatanika basin on the second day caused the river to rise and alter conditions from
the first day and therefore the samples beyond 100 m were discarded. Samples from the Mined ( "0 m"
transec location were taken from representative locations within the entire actively mined area. An area
upstream of any active mining was used as our reference location. Substrate measurements were also
made to document any changes in substrate size or sorting caused by mining. Approximately 25 stones
were chosen at random from near the location of each macroinvertebrate sample. Each stone was
measured to the nearest cm and embeddedness was determined. Embeddedness is the portion of stone
covered by fine sediments and is an indication of the amount of interstitial filling.
One-way ANOVA was used to test for statistically significant differences among the four locations in
Resurrection Creek. Prior to analysis, the data were transformed using either natural log (X) or aresin
(square root (X)) as appropriate (Zar 1984). Pairwise comparisons were conducted using the Tukey HSD
test.
Results
At the time of sampling, total alkalinity, total hardness, and specific conductance in Resurrection Creek
were 29 mg CaC03/L, 69 mg CaC03/L, and 110 pS / cm, respectively. Mean benthic organic matter (BOM)
ranged from approximately 15 to 30 g / m2 among the four sampling locations (Fig. 37), but ANOVA
indicated no significant differences (p=0.252). Mean chlorophyll-a was greatest in the mining area and the
location immediately downstream, but the differences among the means were not significant (p=0.182)
(Fig. 37). Periphyton AFDM showed a pattern similar to chlorophyll-a, with the greatest mean values in the
mined area, but here too the differences were not significant (p=0.064) (Fig. 37). The reach of Resurrection
Creek in which suction dredging occurs is bordered by a campground and numerous foot trails along the
stream. The riparian canopy along that section of Resurrection Creek appeared reduced, relative, to areas
downstream, by the activities associated with recreational mining (e.g., stream-side camping). The reduced
riparian shading (= increased solar radiation) may be responsible for the trend towards greater periphyton
AFDM and chlorophyll-a observed in the mined area and the location immediately downstream. Additionally,
these results suggest that activities other than the actual dredging, such as long-term camping, firewood
collection, trampling of vegetation, etc., also may have an impact on streams open to recreational suction
dredging.
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The pattern seen with periphyton was not observed for macroinvertebrates in Resurrection Creek. Mean
density was 3,700 individuals per m2 in the mined area, and ranged from 4,300 to 4,500 individuals per m2
in the other three locations, although the variability was large and the differences not significant (p=0.581)
(Fig. 38). Total taxa richness from about 17 to 19 among the four locations (p=0.811). The number of EPT
taxa was not significantly different among the sites (p=0.415), although the mean values increased from
9.5 at the upstream location to 11 taxa at the most downstream location (Fig. 38).
Results from the Chatanika River showed a trend toward decreasing macroinvertebrate density as well as
less variable distribution of those macroinvertebrates with distance from active dredging (Fig 39). Average
densities decreased from 6000 per m2 at the reference location, to 2000 per m2 150 m downstream of the
mined area. The number of taxa per sample was more even among locations, ranging from 10 to 13 taxa
per sample. EPT taxa per sample also showed a slight trend toward decreasing numbers downstream of the
mined area, ranging from 6 EPT taxa at 150 m, to 8 EPT taxa at the reference area. Mean amounts of BOM
were greater within the mined area (10 g/m2) than within the reference area (6 g/m2) or the 50 and 100
m areas (7 g/m2 each) (Fig. 40). Substrate measurements showed little change among locations, ranging
from 11 to 15 cm. Substrate embeddedness also averaged 15 to 24 percent (Table 5). The mined areas
showed no discernable trends toward any significant change from the reference area.
Based on density, taxa richness, and EPT richness, there was no difference in the macroinvertebrate
community between the mined area and the locations downstream. The relative abundance of Plecoptera
(stoneflies) was significantly greater at the two downstream locations than in the mined area (p=0.037)
(Fig. 32). However, if the observed reduction was a result of recreational suction mining, downstream
recovery was rapid (i.e., by 35 m).
In general, other studies on the effects of recreational suction dredging have reported only localized
reductions in macroinvertebrate abundance (Sourer and Hassler 1992, Harvey 1986, Thomas 1985).
Studies that examined temporal recovery have found that macroinvertebrates return to pre-dredging
densities within 30-45 days (Harvey 1986, Thomas 1985). Our sampling in Resurrection Creek occurred
approximately 35 days after suction dredging had ended for the year. Thus, it is not surprising that the
abundance and diversity of macroinvertebrates was not significantly different between the mining area and
the locations downstream. Results from a concurrent but separate study not funded by the EPA in 1998 also
suggest considerable redistribution of BOM downstream of mining areas and reduced numbers of
macroinvertebrates (both richness and density) within those mined areas immediately following the end of
the mining season (A.M. Prussian, pers. comm.).
The results presented here on the effects of recreational suction dredging on macroinvertebrates are
derived from a one-time sampling of only two streams. All of the streams specified in the litigation, plus an
additional 13 streams were examined for compatibility with the study design. The two sites presented here
represent the best examples of concentrated mining activity we could find and should be considered "worst-
case" scenarios because both streams receive considerable mining activity and have relatively well-defined
downstream boundaries. The remaining sites suggested in the litigation were either not as intensively
mined or do not contain easily identified mining boundaries. Together with the results of other studies, we
suggest that the impacts by small-scale dredging activity are primarily contained within mined areas and
persist for about one month after the mining season. However, other studies suggest a high degree of
variability among streams in terms of impact caused by small-scale dredges (A.M. Prussian, pers. comm.)
confounding our ability to draw broad conclusions for small-scale mining impacts on stream ecosystems in
the State of Alaska. Additional study is needed to fully quantify the impact of suction dredge mining on the
environment of Alaska before final conclusions are reached regarding the effects of this activity on Alaskan
streams and their associated plant and animal communities.
Acknowledgments
This project could not have been completed without the help of numerous individuals. Gretchen Hayslip
(EPA), Steve McGroarty (Alaska DNR), and Phil North (EPA) assisted in the planning and development of
the study. Field sampling was accomplished with the help of Jeff Davis, Mike Monaghan, Eric Snyder, and
Steve Thomas. Larry Taylor, Pat Scofield, and Scott Reed and Dave Hatch kindly allowed us access to their
mining sites. In the laboratory, Angela Bright, Christine Fischer, Jamie Larson, Cary Myler, Cecily Nelson,
Mark Overfield, Kelly Sant, Amanda Rugenski, Maria Blackhorse, Mark Sjostrom, Chris Seeley, and Jacklynn
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Johnson helped with sample processing and data entry. Taxonomic identification of the aquatic
macroinvertebrates was performed with the help of Christina Relyea. Jim Crock and Larry Gough of the
USGS facilitated sample processing and heavy metal analysis of the macroinvertebrates. The EPA laboratory
in Manchester, WA conducted heavy metal analysis of suspended and dissolved samples. Judy Minshall and
Marie Davis assisted with logistics and purchasing of field supplies. Funding for this research was provided
through a contract with the US Environmental Protection Agency.
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