20030179 Ver 6_Public Comments_20071026 (3)

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C A R O L I N A U N I V E R S I T Y
DEPARTMENT of GEOSCIENCES ArrD NATURAL RESOURCES MANAGEMENT
Mr. Steve Tedder
A'f`fN: John Dorney D ~~~~~~ D
NC Division of Water Quality
401/Wetlands Unit OCT 2 6 2007
1650 Mail Service Center
Raleigh, NC 27699-1650 DENR _ WATER QUALITY
October 23, 2007 1NEflAND3ANDSTOftbNdATSRBRANCH
Dear Mr. 'Tedder:
"Phis letter provides comments on the monitoring plan in Duke Energy's 401/404 Application for the
Dillsboro Dam Removal Project and is submitted by the Geology faculty at Western Carolina University.
In numerous cases, the long-term benefits of dam removal have been shown scientifically to outweigh
short-term impacts. Key to the decommissioning of any dam is an effective, scientifically based
monitoring plan, which is the focus of this letter. It is important to monitor pre- and post- removal
conditions as carefully as possible to 1) allow adaptive management during the removal to safeguard
water quality and stream habitat, and 2) better plan future dam removal projects in Western North
Carolina and elsewhere. Our comments are framed around issues related to monitoring parameters from
pre- to post dam removal and a concern regarding chemical evaluation of the older sediment within the
reservoir.
~'he 401/404 Application describes the monitoring of the river at 14 sites pre- to post-dam removal. It
appears that that there will be a total of four days of river monitoring in the year preceding the dam
removal. On each of those days the tests include conductivity, DO, pH, turbidity, temperature, TSS,
velocity and depth. Continuous monitoring will occur only for DO and temperature at one site upstream
and another downstream from the dam. Other tests may occur during rainfall events. The testing during
the dredging phase is scheduled more frequently. Finally, monitoring will be again run quarterly for four
or five years after the dam has been removed.
Our primary concern is the paucity of data to be collected. Most water quality parameters (including pH,
dissolved oxygen, turbidity, total suspended solids, and chemical pollutants) vary dramatically with
discharge, higher values associated with higher Flood events. In addition, hysteresis effects can lead to
different parameters during rising and falling water levels of an individual flood, even when discharge
conditions are similar, thereby causing significant variations in data. The number of measurements, four
sample sets per year, for pre- and post- dam removal is ridiculously small, and is unlikely to reflect the
changes in any of the measured water quality parameters during moderate to high flow events. Moreover,
it is absolutely essential to collect water level/discharge data to interpret the cause (s) of any observed
variations in the obtained water quality parameters. Our position is that without adequate measurements
it will be impossible to detect changes that may result from dam removal, and the analysis (as currently
designed) will be meaningless.
207 Stillwell Building
Cullowhee, NC 28723-9047
Office: [phone]
Fax: [phone]
Western Carolina University is a campus of the University of North
Carolina and an affirmative action/equal opportunity institution.

We suggest that a minimum of four to five fixed-location monitoring sites be installed up- and
downstream from the dam which allow for (1) the collection of information over short-time intervals
(minutes), and (2) and its recording in digital form on a data logger for easy manipulation and
interpretation. A number of companies currently manufacture such systems, and their installation is quite
simple. In brief, the data are collected using submerged probes and can include such parameters as water
depth and velocity (and, therefore, discharge), turbidity, electrical conductivity, temperature, dissolved
oxygen, and pH. Collection of these nearly continuous data can be combined with water samples
obtained using an automatic sampler (as made by Isco) which allow water samples to be pumped into pre-
cleaned bottles during fluctuating flow conditions (floods). Actual water samples are necessary to
conduct analysis of total suspended solids as well as most organic and inorganic pollutants.
Duke Energy's 401/404 application is rightly concerned about changing channel morphology during
release of water and sediment and it includes construction of channel cross sectional profiles at each of
the 14 sites. As above we are concerned that the type and number of profiles plotted are far too few.
Fifty cross sectional profiles downstream of the dam is likely to give a more reasonable estimate of what
is occurring within the channel than the 14 proposed. Also, there is no mention of construction of at least
localized longitudinal profiles which are likely to provide better insights into changes on the stream bed.
The second sentence on page 3l, Section 5-1, reads "The majority of this sediment is sand and gravel
with very little fines." In the Appendix there is a document titled Sediment Contaminants at Dillsboro
Reservoir: Report on Site Assessment and Sediment Analyses. The Sample Collection section on page 2 of
the document states °`At each site, two to six grabs of the top 5 to 10 cm of sediment were collected and
composited to form one sample per site." Therefore, only the top 10 cm of sediment were analyzed for
contaminants and grain size. During the spring of 2005 a 2 meter sediment core was extracted by geology
faculty and students at Western Carolina University. That core showed a sequence of sediment fining
downward with fine grained (> 20% mud) mixed with organic material.
If indeed the fining downward pattern of sediment is common, this is another cause of concern. The
lower sediment layers within the reservoir are older and are likely to have been deposited before the
Clean Water Act came into existence. Fine grained organic rich sediment is known to hold contaminants
more readily than coarser grained sediments. Therefore, we suggest that if fine grained sediments are
encountered during dredging then grab samples should be collected and analyzed for potential chemical
(organic and inorganic) contaminants.
Continuous monitoring of the Tuckasegee River during all phases of the Dillsboro Dam removal is
essential to understanding and maintaining the health of the riverine system. Continuous monitoring will
provide the data to better manage the dam removal process and to restore the river. From a scientific and
engineering view the data collected in this proposal is likely to be very useful to other dam removal
projects and can be used as a model.
In order to move this dam removal project forward we encourage strong consideration of our
recommendations. Thank you for the opportunity to contribute to this discussion.
Sinc ely,
teven P. Yur ovi ,Professor of Geology
~b ~ ~~~
Rob Young, Pro ssor of Geology
Associate Professor of Geology

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Ben Tanner, Assistant Professor of Geology
Dave Kinner, Assistant professor of Geology
_. _.
Cheryl aters-Tormey, Assista Professor of Geology Bair Tormey, Instruct of Geology
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Susan Barbour-Wood, Assistant Professor of Geology