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Susitna-Watana Hydroelectric Project Document
ARLIS Uniform Cover Page
Title:
SuWa 268
Mercury assessment and potential for bioaccumulation study (Study 5.7),
Errata to evaluation of continued mercury monitoring beyond 2014
technical memorandum (September 30, 2014)
Author(s) – Personal:
Author(s) – Corporate:
Tetra Tech
AEA-identified category, if specified:
November 14, 2014 technical memorandum filings
AEA-identified series, if specified:
Series (ARLIS-assigned report number): Existing numbers on document:
Susitna-Watana Hydroelectric Project document number 268
Published by: Date published:
[Anchorage, Alaska : Alaska Energy Authority, 2014] November 2014
Published for: Date or date range of report: Alaska Energy Authority
Volume and/or Part numbers:
Final or Draft status, as indicated:
Attachment N
Document type: Pagination:
Technical memorandum 1, ii, 13, 16 p.
Related work(s): Pages added/changed by ARLIS:
Cover letter to this report: Susitna-Watana Hydroelectric Project,
FERC Project no. 14241-000; Filing of Initial Study Plan Meetings
transcripts and additional information in response to October 2014
Initial Study Plan Meetings. (SuWa 254)
Attachments A-M (SuWa 255-268)
Mercury assessment and potential for bioaccumulation study (Study
5.7), evaluation of continued mercury monitoring beyond 2014,
technical memorandum. (SuWa 249)
Added cover letter (4
pages)
Notes:
This document consists of errata. PDF pages 3-18 replace the entirety of SuWa 249. PDF pages
19-34 replace pages 100-115 in Part B of SuWa 256.
All reports in the Susitna-Watana Hydroelectric Project Document series include an ARLIS-
produced cover page and an ARLIS-assigned number for uniformity and citability. All reports
are posted online at http://www.arlis.org/resources/susitna-watana/
November 14, 2014
Ms. Kimberly D. Bose
Secretary
Federal Energy Regulatory Commission
888 First Street, N.E.
Washington, D.C. 20426
Re: Susitna-Watana Hydroelectric Project, Project No. 14241-000
Filing of Initial Study Plan Meetings Transcripts and Additional Information in
Response to October 2014 Initial Study Plan Meetings
Dear Secretary Bose:
By letter dated January 28, 2014, the Federal Energy Regulatory Commission
(Commission or FERC) modified the procedural schedule for the preparation and review
of the Initial Study Report (ISR) for the proposed Susitna-Watana Hydroelectric Project,
FERC Project No. 14241 (Project).1 As required by the Commission’s January 28 letter,
the Alaska Energy Authority (AEA) filed the ISR with the Commission on June 3, 2014
and conducted ISR meetings on October 15, 16, 17, 21, 22, and 23, 2014. Attached as
Attachments A-1 through F-2 are the written transcripts (along with the agenda and
PowerPoint presentations) for these ISR meetings.
During the October ISR meetings, AEA and licensing participants identified
certain technical memoranda and other information that AEA would file with the
Commission by November 15, 2014. In accordance, AEA is filing and distributing the
following technical memoranda and other information:
• Attachment G: Glacier and Runoff Changes (Study 7.7) and Fluvial
Geomorphology (Study 6.5) - Assessment of the Potential for Changes in
Sediment Delivery to Watana Reservoir Due to Glacial Surges Technical
Memorandum. This technical memorandum documents AEA’s analysis of the
potential changes to sediment delivery from the upper Susitna watershed into
the Project’s reservoir from glacial surges.
• Attachment H: Riparian Instream Flow (Study 8.6) and Fluvial
Geomorphology (Study 6.6) - Dam Effects on Downstream Channel and
Floodplain Geomorphology and Riparian Plant Communities and Ecosystems
− Literature Review Technical Memorandum. This literature review technical
1 Letter from Jeff Wright, FERC Office of Energy Projects, to Wayne Dyok, Alaska Energy Authority,
Project No. 14241-000 (issued Jan. 28, 2014).
2
memorandum synthesizes historic physical and biologic data for the Susitna
River floodplain vegetation (including 1980s studies), studies of hydro project
impacts on downstream floodplain plant communities, and studies of un-
impacted floodplain plant community successional processes.
• Attachment I: Susitna River Fish Distribution and Abundance Implementation
Plan, Appendix 3. Protocol for Site-Specific Gear Type Selection, Version 5.
In accordance with the fish distribution and abundance studies, as described in
Revised Study Plan (RSP) Sections 9.5 and 9.6 and in the Fish Distribution
and Abundance Implementation Plan, this appendix establishes the protocol
for site-specific gear type selection for fish surveys. Throughout study plan
implementation, AEA has updated this appendix as needed to provide
consistent direction to all field teams. Version 1 of Appendix 3 was originally
filed with the Fish Distribution and Abundance Implementation Plan in March
2013. That version was updated twice (Versions 2 and 3) during the 2013
field season to accommodate protocol changes that related to FERC’s April 1,
2013 Study Plan Determination, field permits, and lessons learned during
study implementation. Version 4 was the protocol used for the 2014 field
season and was updated with respect to the prioritization of gear use and
based on 2013 data collected. This version herein, Version 5, will be followed
during the 2015 field season.
• Attachment J: Fish Distribution and Abundance in the Upper and
Middle/Lower Susitna River (Studies 9.5 and 9.6): Draft Chinook and Coho
Salmon Identification Protocol. This document established a Chinook and
coho salmon identification protocol to support accurate and consistent field
identification across field teams. It will allow for additional quality control
and assurance of field identification calls and for estimation and reporting of
any field identification error that may occur in future sampling efforts.
• Attachment K: Characterization and Mapping of Aquatic Habitats (9.9),
Errata to Initial Study Report Part A - Appendix A, Remote Line Mapping,
2012. This errata provides a corrected version of map book for Remote Line
Mapping, 2012. The version filed with the ISR (June 3, 2014) used a data
query to build the maps in geomorphic reaches MR-1 to UR-5 that mistakenly
did not include side slough habitat, so that no side sloughs were depicted on
the Appendix A maps 1 through 21. This version was corrected by including
side slough habitat in the data query for geomorphic reaches MR-1 to UR-5.
This version now includes side sloughs.
• Attachment L: Characterization and Mapping of Aquatic Habitats Study 9.9,
Revised Map Book for 2012 Remote Line Mapping. This map book represents
an update to the version published on June 3, 2014 with the Study 9.9 Initial
Study Report and the errata provided concurrently with this filing (see
Attachment K). The maps presented include all macrohabitat and mesohabitat
line identifications available in the 2012 Remote Line Mapping ArcGIS
3
shapefile. This map book should be considered a full replacement for
previous versions and represents the final product for the 2012 remote line
habitat mapping effort.
• Attachment M: Study of Fish Passage Barriers in the Middle and Upper
Susitna River and Susitna Tributaries (Study 9.12), Fish Passage Criteria
Technical Memorandum. This technical memorandum presents a proposed
final list of fish species that will be included in the fish barrier analysis as well
as depth, leaping and velocity passage criteria for selected fish species. AEA
previously consulted with the federal agencies and other licensing participants
regarding the information within the technical memorandum during a March
19, 2014 Fisheries Technical Meeting.
In addition to the technical memoranda and other information identified above,
AEA is filing a short errata (Attachment N) to the Mercury Assessment and Potential for
Bioaccumulation Study (Study 5.7), Evaluation of Continued Mercury Monitoring
Beyond 2014 Technical Memorandum. This technical memorandum, which was
originally filed on September 30, 2014, evaluates the need for continued monitoring of
mercury data beyond 2014 and whether the existing data collection efforts are sufficient
to satisfy objectives for characterizing baseline mercury conditions in the Susitna River
and tributaries (RSP Section 5.7.1). Since the filing of this TM and based upon the
ongoing QA/QC of the data reported in that TM, AEA discovered errors in the TM. The
attached TM corrects those errors. Additionally, the errata corrects corresponding errors
in the Mercury Assessment and Potential for Bioaccumulation presentation presented
during the October 16, 2014 ISR meeting.
Finally, AEA notes that data collected during the Study Plan implementation, to the
extent they have been verified through AEA’s quality assurance and quality control (QAQC)
procedures and are publicly available, can be accessed at http://gis.suhydro.org/isr_mtg. On
November 14, 2014, AEA posted the following data to this website:
• Baseline Water Quality Data (Study 5.5), 2013 QAQC water quality data
and DVRs per the Quality Assurance Project Plan.
• Breeding Survey Study of Landbirds and Shorebirds (Study 10.16),
cumulative 2013-2014 data.
• Characterization and Mapping of Aquatic Habitats (Study 9.9), ArcGIS
shapefile “ISR_9_9_AQHAB_RemoteLineMapping_2012.shp” used to
generate the maps in Attachment L.
4
AEA appreciates the opportunity to provide this additional information to the
Commission and licensing participants, which it believes will be helpful in determining
the appropriate development of the 2015 study plan as set forth in the ISR. If you have
questions concerning this submission please contact me at wdyok@aidea.org or (907)
771-3955.
Sincerely,
Wayne Dyok
Project Manager
Alaska Energy Authority
Attachments
cc: Distribution List (w/o Attachments)
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
Mercury Assessment and Potential for Bioaccumulation
Study (Study 5.7)
Errata to Evaluation of
Continued Mercury Monitoring Beyond 2014
Technical Memorandum (September 30, 2014)
Prepared for
Alaska Energy Authority
Prepared by
Tetra Tech
November 2014
TECHNICAL MEMORANDUM EVALUATION OF CONTINUED MERCURY MONITORING BEYOND 2014
ERRATA TO EVALUATION OF CONTINUED MERCURY MONITORING BEYOND 2014
TECHNICAL MEMORANDUM (ORIGINALLY FILED SEPTEMBER 30, 2014)
TM Reference Errata Description
Study 5.7 Technical
Memorandum, Mercury
Assessment and Potential
for Bioaccumulation,
Evaluation of Continued
Mercury Monitoring
Beyond 2014; page 11,
Figure 5.5-1
Replaced Figure 5.5-1 with a revised version. Changes in the figure include:
1) addition of notation at bottom of the Water Column Dissolved Hg/Water
Column Total Hg box reporting average concentrations of mercury
“(Provisional Data; Under Review)”, and 2) “Dry Otter and Mink Fur Hg”
box revised to reflect splitting of Hg results into “Dry Mink Fur Hg” and
“Dry Otter Fur Hg”. Average concentration of Hg as dry weight in mink fur
is 6,258 ng/g. These samples were not collected within the study area of the
proposed reservoir.
Study 5.7 Technical
Memorandum, Mercury
Assessment and Potential
for Bioaccumulation,
Evaluation of Continued
Mercury Monitoring
Beyond 2014; page 14,
Table 6.1-1
Replaced Figure 6.1-1 with a revised version. Maximum and Minimum
concentrations of mercury (Hg) in Dry Mink Fur samples revised; maximum
concentration was incorrectly reported as 29,950 ng/g, but that was actually
a “post-spike” sample concentration intended to evaluate potential
interference elements in the matrix. The correct maximum concentration for
this sample is 7,670 ng/g dry weight and minimum concentration is 4,180
ng/g. The “Dry Otter/Mink Fur Hg” tissue results are split into separate
categories: “Dry Mink Fur Hg” and “Dry Otter Fur Hg”. In addition, Otter
Fur collected from within the study area is reported as “Wet Wt. Otter Fur
Hg”. The Table 6.6-1 now includes additional summary statistics for each of
the media analyzed for Hg: 1) mean concentration, 2) Standard Deviation ,
and 3) number of observations. Additional footnotes (4 & 5) are added at the
bottom of the Table 6.1-1. Data for Piscivorous Mammals is provisional
until final quality assurance review is completed.
Initial Study Report
Meeting Presentation (ISR
5.7), Study 5.7 Mercury
Assessment and Potential
for Bioaccumulation
• Slide 6, 1st bullet, 4th sub-bullet, beginning of first sentence: changed “60
fish tissue samples” to “67 fish tissue samples”.
• Slide 7, Second bullet, end of second sentence: “total of 13 results”
changed to “ total of 14 results”.
• Slide 8, Table replaced with revisions based on those made in Table 6.1-1
from “Study 5.7 Technical Memorandum, Mercury Assessment and
Potential for Bioaccumulation, Evaluation of Continued Mercury
Monitoring Beyond 2014”; page 14, Table 6.1-1.
• Slide 9, Figure replaced with revisions based on those made in Figure 5.5-
1 from “Study 5.7 Technical Memorandum, Mercury Assessment and
Potential for Bioaccumulation, Evaluation of Continued Mercury
Monitoring Beyond 2014”; page 11, Figure 5.5-1.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 1 November 2014
Susitna-Watana Hydroelectric Project
(FERC No. 14241)
Mercury Assessment and Potential for Bioaccumulation
Study (Study 5.7)
Evaluation of Continued Mercury Monitoring Beyond 2014
Technical Memorandum
Prepared for
Alaska Energy Authority
Prepared by
Tetra Tech
September 2014
(revised per errata November 14, 2014)
TECHNICAL MEMORANDUM EVALUATION OF CONTINUED MERCURY MONITORING BEYOND 2014
TABLE OF CONTENTS
1. INTRODUCTION ............................................................................................................................... 1
2. STUDY OBJECTIVES ....................................................................................................................... 1
3. STUDY AREA ..................................................................................................................................... 2
4. ELEMENTS REQUIRED TO COMPLETE THE STUDY ........................................................... 2
4.1 Planned Monitoring Components in 2014 .................................................................................... 3
5. STUDY COMPONENTS COMPLETED IN 2014 .......................................................................... 3
5.1 Geologic Studies for the Inundation Zone .................................................................................... 3
5.2 Collection of Sediment and Porewater Samples ........................................................................... 3
5.3 Limited Winter Water Quality Sampling ...................................................................................... 4
5.4 Summer Monthly Sampling .......................................................................................................... 4
6. APPROACH FOR STUDY COMPLETION ................................................................................... 4
6.1 Pathway and Threshold Analyses ................................................................................................. 4
6.1.1 Data Applied to Pathways Analysis ...................................................................................... 5
6.1.2 Application of the Pathway Model ....................................................................................... 5
6.2 Comparison to Existing Criteria and Thresholds .......................................................................... 6
7. STEPS TO COMPLETE THE STUDY ............................................................................................ 7
7.1 Data Verification/Validation ......................................................................................................... 7
8. RECOMMENDATIONS .................................................................................................................... 7
9. REFERENCES .................................................................................................................................... 8
10. FIGURES ............................................................................................................................................. 9
11. TABLES ............................................................................................................................................. 12
LIST OF FIGURES
Figure 1-1. Factors in the Environment that Effect Mercury Bioconcentration and Bioaccumulation. ...... 9
Figure 1-2. Potential Mercury in a Mature Reservoir. ............................................................................... 10
Figure 5.5-1. Average 2013 Mercury Concentrations and Pathways for Transfer of Mercury in the
Susitna Basin. ..................................................................................................................................... 11
LIST OF TABLES
Table 5.3-1. 2014 Winter Sampling at Baseline Water Quality Monitoring Sites and Parameters. .......... 12
Table 5.3-2. 2014 Winter Sampling at Groundwater Well Monitoring Sites in Select Focus Areas. ........ 12
Table 6.2-1. Concentrations of Mercury Compared to Criteria or Thresholds. ......................................... 13
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page i September 2014
TECHNICAL MEMORANDUM EVALUATION OF CONTINUED MERCURY MONITORING BEYOND 2014
LIST OF ACRONYMS, ABBREVIATIONS, AND DEFINITIONS
Abbreviation Definition
ADEC Alaska Department of Environmental Conservation
AEA Alaska Energy Authority
AWQS Alaska Water Quality Standards
FA(s) Focus Area(s)
FERC Federal Energy Regulatory Commission
ILP Integrated Licensing Process
MeHg Methylmercury
NOAA National Oceanic and Atmospheric Administration
NTU Nephelometric turbidity unit
PRM Project River Mile
Project Susitna-Watana Hydroelectric Project
RSP Revised Study Plan
SQuiRT(s) Screening Quick Reference Table(s)
TEL Threshold Effects Level
USACE U.S. Army Corps of Engineers
USGS U.S. Geological Survey
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page ii September 2014
TECHNICAL MEMORANDUM EVALUATION OF CONTINUED MERCURY MONITORING BEYOND 2014
1. INTRODUCTION
The Alaska Energy Authority (AEA) is preparing a License Application that will be submitted to
the Federal Energy Regulatory Commission (FERC) for the Susitna-Watana Hydroelectric
Project (Project) using the Integrated Licensing Process (ILP). The Project is located on the
Susitna River, an approximately 320-mile-long river in Southcentral Alaska. The Project’s dam
site would be located at Project River Mile (PRM) 187.1.
Mercury contamination is widely known to present human health concerns. In the environment,
processes such as reducing and low oxygen conditions can lead to increased rates of mercury
methylation (Figure 1-1). Based on several studies, mercury that is found in newly formed
reservoirs originates predominantly from inundation of organic soils (Figure 1-2). The linkage
between sediment sources, mobilization into the water column (dissolved form), and the
potential for bioaccumulation in fish tissue and piscivores therefore presents a human health
concern with respect to mercury contamination. Methylmercury (MeHg) bioaccumulates, and the
highest concentrations are typically in the muscle tissue of adult predatory fish. Targeting adult
fish is a good way of monitoring methylmercury migration to the larger environment. Potential
for bioaccumulation in aquatic life is determined when chronic thresholds for toxics exposure in
a medium are identified. Potential for mortality is determined when acute criteria for toxics in a
medium are exceeded.
A Mercury and Potential for Bioaccumulation Study (Study 5.7) was initiated in 2013 to answer
key questions (Revised Study Plan [RSP] Section 5.7.1; AEA 2012) and determine: 1) whether
conditions within the reservoir will cause mercury methylation from inundated conditions, 2) the
concentrations of methylmercury that might occur, and 3) whether a mechanism exists to transfer
that methylmercury to wildlife, resulting in detrimental impacts.
Data on the mercury concentration in sediment, sediment porewater, soil, vegetation, water, fish,
and piscivorous mammals have been collected within the past two years (2013/2014) within the
Susitna River basin. These data were further evaluated for adequacy in representation of current
conditions in and around the Susitna River. The need for continued monitoring of mercury data
beyond 2014 is being evaluated to determine whether the existing data collection efforts are
sufficient to satisfy objectives for characterizing baseline mercury conditions in the Susitna River
and tributaries (RSP Section 5.7.1).
2. STUDY OBJECTIVES
Based on several studies, the mercury that is found in newly formed reservoirs originates
predominantly from inundation of organic soils. Receptors are and will be present in the
inundation area (macroinvertebrates, fish, birds, etc.). Mercury methylation in reservoirs is a
fairly well understood process, and numerous models exist to predict the occurrence and
magnitude of the phenomena.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 1 September 2014
TECHNICAL MEMORANDUM EVALUATION OF CONTINUED MERCURY MONITORING BEYOND 2014
Given these known factors, key questions that need to be answered by this study include the
following:
1) Whether conditions within the reservoir will cause mercury methylation from this source.
2) The concentrations of methylmercury that might occur.
3) Whether a mechanism exists (fish and small invertebrates living in the methylation zone)
to transfer that methylmercury to wildlife, resulting in detrimental impacts.
Study 5.7 assesses the status of mercury concentrations in several media and mercury cycling
between the aquatic and terrestrial environment. Based on these questions, specific objectives of
Study 5.7 study are as follows:
• Summarize available and historic water quality information for the Susitna River basin,
including data collection from the 1980s Alaska Power Authority (APA) Susitna
Hydroelectric Project.
• Characterize the baseline mercury concentrations of the Susitna River and tributaries.
This will include collection and analyses of vegetation, soil, water, sediment pore water,
sediment, piscivorous birds and mammals, and fish tissue samples for mercury.
• Utilize available geologic information to determine if a mineralogical source of mercury
exists within the inundation area.
• Map mercury concentrations of soils and vegetation within the proposed inundation area.
This information will be used to develop maps of where mercury methylation may occur.
• Use the water quality model to predict where in the reservoir conditions (pH, dissolved
oxygen, turnover) are likely to be conducive to methylmercury formation.
• Use modeling to estimate methylmercury concentrations in fish.
• Assess potential pathways for methylmercury to migrate to the surrounding environment.
• Coordinate study results with other study areas, including fish, instream flow, and other
piscivorous bird and mammal studies.
3. STUDY AREA
As established in Study Plan Section 5.7.3, the study area begins at project river mile (PRM)
19.9 and extends upstream from the proposed reservoir to PRM 235.2. An overview map and
detailed sample locations are provided in the Initial Study Report (ISR) (AEA 2014).
4. ELEMENTS REQUIRED TO COMPLETE THE STUDY
AEA initiated the Mercury Assessment of Potential for Bioaccumulation Study in 2013. To meet
study goals, AEA completed numerous study components which are summarized in ISR Study
5.7 Section 5. The following sections describe study components planned for 2014.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 2 September 2014
TECHNICAL MEMORANDUM EVALUATION OF CONTINUED MERCURY MONITORING BEYOND 2014
4.1 Planned Monitoring Components in 2014
AEA summarized its plans for completing the Mercury Assessment and Potential for
Bioaccumulation Study in ISR Study 5.7, Part C, Section 7 as follows:
• Geologic studies for the inundation zone.
• Collection of sediment samples at the six remaining sites located on CIRWG lands (RSP
Section 5.7.4.2.4).
• Limited winter water quality sampling in January and March of 2014 (RSP Section
5.7.4.2.3).
• Summer monthly water sampling from June to September 2014 (see ISR Section 5.5 for
details).
• Completion of the Predictive Risk Analyses (RSP Section 5.7.4.6) and mercury modeling
(RSP Sections 5.7.4.7 and 5.7.4.8).
5. STUDY COMPONENTS COMPLETED IN 2014
The 2014 efforts focused on the collection of water and sediment mercury and methylmercury to
aid in the creation of a pathways analysis model used to determine the need for further mercury
sampling in other media. Specific study components completed in 2014 are summarized below.
5.1 Geologic Studies for the Inundation Zone
The ISR Study 4.5, Part C Section 7.2 states the following elements and 2015 schedule for
geologic mapping of the area to be inundated by the reservoir:
Geologic Mapping – summer mapping to be scheduled prior to leaf-out and after leaves have
fallen (May and September) for geologic mapping associated with regional geology
development, mineral resources and claims, reservoir rim stability, and a continuation of
geologic mapping as needed for lineaments and geologic features (potential fracture and shear
zones) and evaluation of rock displacement or rupture in the dam site area.
Results from this geologic characterization of the inundated land will be used to determine
potential for mobilization of mercury in the reservoir. This study is on-going and is not yet
completed.
5.2 Collection of Sediment and Porewater Samples
Sediment and porewater samples were collected at the six remaining sites located on CIRWG
lands (RSP Section 5.7.4.2.4) in 2014: Susitna River just below and above the proposed dam site,
and the mouths of Fog, Tsusena, Deadman, and Watana Creeks (Section 5.5.4.6 of the RSP;
Section 4.5 of the ISR).
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 3 September 2014
TECHNICAL MEMORANDUM EVALUATION OF CONTINUED MERCURY MONITORING BEYOND 2014
5.3 Limited Winter Water Quality Sampling
Winter samples were collected from five baseline monitoring sites in January 2014 and March
2014 (Table 5.3-1). Field parameters were collected on-site during each visit and laboratory
parameters generated following analysis of samples. Laboratory data from 2014 winter sampling
has been completed and is now undergoing a quality assurance review. The procedure for a
quality assurance review includes development of a Data Validation/Verification Report (DVR)
for ten percent of all samples collected for this winter monitoring program. The DVR is a data
review requirement of ADEC to ensure compliance with use of high quality data used to make
regulatory decisions.
Three groundwater wells previously established in Focus Areas FA-104 (Whiskers Slough), FA-
128 (Slough 8A), and FA-138 (Gold Creek) were sampled in February 2014, March 2014, and
April 2014 (Table 5.3-2). Both field and laboratory parameter results were generated on three
separate sampling dates. Raw data is currently being reviewed to assure it meets acceptance
limits per the Quality Assurance Project Plan for Water Quality and Mercury Assessment for the
Susitna-Watana Hydroelectric Project Susitna River, Southcentral Alaska (QAPP).
5.4 Summer Monthly Sampling
Total mercury samples were collected from baseline water quality and seven Focus Area (FA)
transects identified in ISR Study 5.7 Sections 4.3 and 4.4, respectively, from June to September
2014. Total mercury samples were collected from one location on a transect at each of the
baseline water quality sites. Total mercury samples were also collected from each transect within
seven Focus Areas (Table 5.4-1). If a transect within a Focus Area crossed braided channels
then one total mercury sample was collected from the mainstem and another from the braided
channel area. A single fur sample was collected outside the inundation area and was the only
sample gathered during the 2014 field studies.
6. APPROACH FOR STUDY COMPLETION
6.1 Pathway and Threshold Analyses
An illustrative pathway model was constructed that reports concentrations of total, dissolved, and
methylmercury measured in various receptors in the Susitna River drainage (Figure 5.5-1) and
describes a preliminary evaluation of potential transfer between media (e.g., sediment– sediment
porewater, porewater–surface water, surface water–fish tissue). A final analysis of potential for
mercury bioaccumulation will combine evaluation of criteria or threshold exceedance and if
these concentrations promote transfer between connected components of the pathway (Figure 1-
2) model. An additional diagram as seen in Figure 1-2 will be constructed for the new reservoir
and include wetlands, bogs, and terrestrial vegetation that will be submerged by inundation.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 4 September 2014
TECHNICAL MEMORANDUM EVALUATION OF CONTINUED MERCURY MONITORING BEYOND 2014
6.1.1 Data Applied to Pathways Analysis
Data used to construct the pathway model were primarily based on data collected in 2013 that
have undergone QA/QC review. Presence of mercury in each of the media sampled and
analyzed is identified and used to determine if a concentration gradient is present (e.g., potential
for transfer from sediment to porewater, porewater to surface water, and sediment to biota).
Evaluation for adequacy of data used in pathways analysis was based on factors like
completeness in sampling all media, determination for adequacy of number of samples collected
in each media, and spatial representation of the sampled media.
Fourteen sediment and sediment porewater samples were analyzed for total mercury in 2013 and
used in the preliminary pathways assessment. Fish sample collection occurred in August through
October 2013. Liver samples were also collected from burbot and analyzed for total mercury and
MeHg. A single fur sample collected from mink and otter outside the Project area was collected
in March 2014 and analyzed for total mercury. A total of 50 soil and vegetation samples from
five sites in each of ten locations within the reservoir inundation zone were collected during
August 2013. Vegetation and soil samples were analyzed for total mercury and MeHg. Each soil
and vegetation sample was analyzed for concentrations of mercury in wet samples and dry
weight results were calculated. In all cases dry weight sample concentrations (calculated values)
exceeded wet weight sample concentrations. Dry weight sample concentration results were used
in the current mercury conceptual pathway assessment.
6.1.2 Application of the Pathway Model
The initial approach used to assess mercury data from various media was to compare data with
existing and appropriate water quality criteria, sediment thresholds, and fish tissue screening
levels. Surface water results were compared to Alaska Water Quality Standards (18 ACC
70.020(b)) for protection of beneficial uses in fresh water and to criteria for protection of human
health. Sediment and fish tissue results were compared to the Screening Quick Reference Tables
(SQuiRTs) used by the National Oceanic and Atmospheric Administration (NOAA) to determine
if the threshold effects level (TEL) to aquatic life have been exceeded. Table 6.1-1 summarizes
the concentrations of mercury compared to criteria or thresholds, including human health as well
as criteria for protection of aquatic life.
Based on discussion provided in Section 5.7.2 of the RSP, naturally occurring deposits of
mercury may occur as parent geology for this element; for example, diorite and granodiorite
have been identified in the proposed inundation zone. Given the limited presence of small-scale
mining in the Project area other sources of mercury could be associated with atmospheric
deposition. Lakes at Glacier Bay, Alaska, have shown that current rates of atmospheric mercury
deposition are almost double the concentration currently than observed during pre-industrial
times (Engstrom and Swain 1997). The presence of mercury in organic rich soils from decades
of post-industrial deposition could be the only source of this element in the inundation zone.
Vegetation samples collected from the area provide some indication of intensity of aerial
deposition based on comparison with concentrations of mercury with known sources of this
element.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 5 September 2014
TECHNICAL MEMORANDUM EVALUATION OF CONTINUED MERCURY MONITORING BEYOND 2014
6.2 Comparison to Existing Criteria and Thresholds
Preliminary examination of 2013 mercury results included a review from each of the media
sampled in both the aquatic and terrestrial environment. Comparison of results with criteria or
effects thresholds was one of the evaluation tools used to review results of mercury
concentrations in each of the media. Table 6.1-1 presents the maximum and minimum
concentrations from observations in each of the sampled media during 2013 and compares the
maximum concentrations with available criteria or thresholds. Comparison to maximum
concentrations is the most conservative approach for determining potential risk of effects from
high mercury concentrations. When the maximum mercury concentration exceeded the criterion,
further examination for how many results exceeded and if most results were near the minimum
concentration as reflected by the average concentration.
Of the 375 samples collected as part of the water quality baseline monitoring study in 2013 were
analyzed for total and dissolved mercury. The Focus Areas had a higher density of sampling
locations, so that prediction of change using the EFDC water quality model could be made with a
higher degree of resolution under Project operations during wet, dry, and average years. Grab
samples collected from the Focus Areas were analyzed for total mercury and methylmercury
generating 300 results. Focus Area water quality mercury sampling results have been compared
with state criteria and thresholds for protection of beneficial uses to evaluate how Project
operations will affect potential fish spawning and rearing habitat.
Based on 2013 sampling results, the average concentration of dissolved mercury in the water
column was 1.06 ng/L (Figure 5.5-1). This average is below the most stringent criterion, of 12
ng/L that is protective of aquatic life. Two dissolved mercury samples collected in June 2013
(from PRM 59.9) and July 2013 (PRM 33.6) exceeded the Human Health criterion of 50 ng/L at
58.7 and 56.4 ng/L, respectively (Table 6.1-1). The remainder of results were well below the
Human Health criterion. Comparison of total mercury concentrations were not compared to the
criterion for protection of aquatic life as results from 2013 did not pass acceptance limits. These
results will be compared against criteria once examination of the 2014 data set is made and
adjustments to 2013 results using a correction factor. Similarly, one mercury result (220 ng/g)
from 14 sediment samples exceeded the recommended SQuiRT Threshold of 174 ng/g.
Concentrations were much lower in the remainder; the overall average mercury concentration in
the sediment samples was 23.01 ng/g.
Background information for mercury in fish tissue was acquired from recent fish tissue analysis
by ADEC with results ranging from 29.07ng/g (total mercury in Sockeye salmon) – 380.0 ng/g
(total mercury in lake trout) in the Susitna Drainage (ADEC 2012). The average concentration
among several species of fish sampled in 2013 from the Susitna drainage was within the range
described by ADEC. Data collected in 2013 was similar to results collected by the 2012 ADEC
effort.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 6 September 2014
TECHNICAL MEMORANDUM EVALUATION OF CONTINUED MERCURY MONITORING BEYOND 2014
7. STEPS TO COMPLETE THE STUDY
7.1 Data Verification/Validation
Revised Study Plan (RSP) Section 5.7.4.2.3 (AEA 2012) stated that AEA would recommend the
need for continuing surface water sampling for mercury in 2014 based on 2013 results. Total
mercury sample results collected in 2013; however, did not meet QA/QC requirement acceptance
limits specified in the QAPP. The review of 2014 sample results will be completed by December
2014 to determine if total mercury estimates in surface water, sediment, and pore water satisfies
acceptance limits and can be used for further data analysis and interpretation. Because ingestion
rates of mercury in piscivores is directly correlated with fish, a determination for potential for
bioaccumulation must initially be completed for aquatic receptors. Identifying a potential source
of mercury from fish (see Section 5.7.4.2 of the RSP) in the Project area must occur before any
conclusions can be made regarding transfer from aquatic to terrestrial receptors. This will be
completed when pathways analysis begins following review of the 2014 data results.
8. RECOMMENDATIONS
Based on results from 2013 sampling, the total mercury concentrations for 2013 from water
column samples are considered high estimates as results did not meet acceptance limits for
laboratory performance. A correction factor will be developed for the 2013 results following
QA/QC review of 2014 data. The concentrations of total mercury in sediments from four sites
that were collected in 2013 are well below SQuiRT TEL and the concentration of total mercury
in sediment porewater (Total Hg) is several times lower than the water column concentration.
The final pathway analysis has not yet been completed and is the next major component of this
study that will determine potential sources for bioaccumulation. Existing fish data collection and
tissue results will be used to identify these potential sources from several media where contact or
ingestion of mercury is possible. Pathways analysis will be used to determine if reservoir and
riverine habitat have the potential for generating methylmercury by using predicted elements
from the Environmental Fluid Dynamic Code (EFDC) model that are known to facilitate the
genesis of methylmercury (Figure 1-1). Post-reservoir conditions will establish potential sources
and location of predicted methylmercury concentrations and the subsequent potential for
bioaccumulation.
Based upon its preliminary review of the mercury results measured in each of the media, AEA is
not proposing any additional sampling for mercury in 2015. Most of the observations
characterizing mercury in each of the media were below existing thresholds or criteria.
Monitoring would be expanded (as stated in Section 5.5.4.4 of the RSP) if metals in surface
water, fish tissue, or sediment exceeded criteria or thresholds. Most of the mercury results in
select media did not exceed available criteria/thresholds, therefore, suggesting no additional
sampling is necessary.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 7 September 2014
TECHNICAL MEMORANDUM EVALUATION OF CONTINUED MERCURY MONITORING BEYOND 2014
9. REFERENCES
ADEC (Alaska Department of Environmental Conservation). 2012. Mercury concentration in
fresh water fish Southcentral Susitna Watershed. Personal communication with Bob
Gerlach, VMD, State Veterinarian. June 2012.
AEA (Alaska Energy Authority). 2012. Revised Study Plan: Susitna-Watana Hydroelectric
Project FERC Project No. 14241. December 2012. Prepared for the Federal Energy
Regulatory Commission by the Alaska Energy Authority, Anchorage, Alaska.
http://www.susitna-watanahydro.org/study-plan.
AEA (Alaska Energy Authority). 2014. Mercury Assessment and Potential for Bioaccumulation
Study, Study Plan Section 5.7. Initial Study Report. June 2014. http://www.susitna-
watanahydro.org/wp-content/uploads/2014/05/05.7_MERC_ISR_PartA.pdf
Engstrom, D.R. and E.B. Swain. 1997. Recent declines in atmospheric mercury deposition in
the Upper Midwest: Environmental Science and Technology, v.31, no.4. p. 960-967.
Frenzel, S.A. 2000. Selected Organic Compounds and Trace Elements in Streambed Sediments
and Fish Tissues, Cook Inlet Basin, Alaska. USGS Water-Resources Investigations
Report 00-4004.
Jewett S.C. and L.K. Duffy. 2007. Mercury in Fishes of Alaska, with emphasis on subsistence
species. Sci. Total Envir. 387(1-3): 3-27.
USGS (U.S. Geological Survey). 2012. Streamflow Record Extension for Selected Streams in
the Susitna River Basin, Alaska, Scientific Investigations Report 2012–5210. 46 p.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 8 September 2014
TECHNICAL MEMORANDUM EVALUATION OF CONTINUED MERCURY MONITORING BEYOND 2014
10. FIGURES
Figure 1-1. Factors in the Environment that Effect Mercury Bioconcentration and Bioaccumulation.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 9 September 2014
TECHNICAL MEMORANDUM EVALUATION OF CONTINUED MERCURY MONITORING BEYOND 2014
Figure 1-2. Potential Mercury in a Mature Reservoir.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 10 September 2014
TECHNICAL MEMORANDUM EVALUATION OF CONTINUED MERCURY MONITORING BEYOND 2014
Figure 5.5-1. Average 2013 Mercury Concentrations and Pathways for Transfer of Mercury in the Susitna Basin.
Mercury Pathways Analysis
Sediment Hg = 23.01 ng/g
Porewater Total Hg= 2.67 ng/L
Water Column Dissolved Hg= 1.06 ng/L
Water Column Total Hg= 25.55 ng/L
(Provisional Data; Under Review)
Dry soil Hg = 60.46 ng/g
Dry Soil MeHg =0 .61 ng/g
Dry Organic Matter Hg= 58.25 ng/g
Dry Vegetation Hg= 9.16 ng/g
Dry Vegetation MeHg= 3.17 ng/g
Dry Fish Hg= 354.23 ng/g
Fish MeHg= 328.69 ng/g
Dry Mink Fur Hg = 6,258 ng/g (4 samples)
Dry Otter Fur Hg = NA (1 sample)
(Note: Not in study area)
Allocthonous Input Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 11 September 2014
TECHNICAL MEMORANDUM EVALUATION OF CONTINUED MERCURY MONITORING BEYOND 2014
11. TABLES
Table 5.3-1. 2014 Winter Sampling at Baseline Water Quality Monitoring Sites and Parameters.
Winter Baseline Water Quality Monitoring
Sampling Date Susitna River PRM Lab Parameters Field Parameters
1/28/2014 29.9, 87.8 TP, SRP, Ammonia, NO3+NO2, TKN,
MeHg, Alkalinity, Hardness, TDS, TSS,
TOC, DOC, Turbidity, Chlorophyll
Dissolved and Total Al, As, Fe, Ba, Be,
Cd, Cr, Co, Cu, Pb, Mo, Ni, Se, Tl, V,
Zn, Mn, Ca, Mg, Hg
Color, Temperature, DO,
pH, Specific
conductance, ORP,
Turbidity
1/29/2014 185, 225
1/30/2014 140
3/10/2014 29.9, 87.8
3/11/2014 185, 225
3/12/2014 140
Table 5.3-2. 2014 Winter Sampling at Groundwater Well Monitoring Sites in Select Focus Areas.
Winter Focus Area Groundwater Well Monitoring
Sampling Date Focus Area Lab Parameters Field Parameters
2/6/2014 FA-104 (Whiskers Slough)
TP, SRP, Ammonia,
NO3+NO2, TKN, MeHg, TOC,
DOC, Turbidity, Dissolved and
Total Al, Fe, Hg
Temperature, pH, Specific
conductance, ORP, DO
2/12/2014 FA-138 (Gold Creek)
2/17/2014 FA-128 (Slough 8A)
3/6/2014 FA-104 (Whiskers Slough)
3/12/2014 FA-138 (Gold Creek)
3/16/2014 FA-128 (Slough 8A)
4/2/2014 FA-104 (Whiskers Slough)
4/9/2014 FA-138 (Gold Creek)
4/13/2014 FA-128 (Slough 8A)
Table 5.4-1. Focus Areas at which water quality sampling occurred.
Focus Area ID (Common Name)
FA-144 (Slough 21)
FA-141 (Indian River)
FA-138 (Gold Creek)
FA-128 (Slough 8A)
FA-115 (Slough 6A)
FA-113 (Oxbow 1)
FA-104 (Whiskers Slough)
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 12 September 2014
TECHNICAL MEMORANDUM EVALUATION OF CONTINUED MERCURY MONITORING BEYOND 2014
Table 6.1-1. Concentrations of Mercury Compared to Criteria or Thresholds.
Sample Matrix Maximum (ng/g dry or ng/L wet)
Minimum (ng/g dry or ng/L wet)
Mean (ng/g dry or ng/ L wet)
Standard Deviation No. of Observations Criteria or Threshold
Hg in Dry
Vegetation
16.1 6.71 9.16 1.9 50
MeHg in Dry
Vegetation
5.15 2.54 3.17 0.53 50
Hg in Dry Organic
Matter
129 26.8 58.25 20.04 55
Hg in Dry Soil 119 27.1 60.46 21.07 55
MeHg in Dry Soil 4.34 0.096 0.61 0.89 55
1Dissolved Hg in
Water Column
58.7 0.5 1.06 4.21 375 Acute = 2,040
ng/L
Total Recoverable
Hg in Water Column
See note 2 See note 2 See note 2 See note 2 See note 2 Aquatic Life:
Chronic = 12 ng/L
Acute = 2,400
ng/L
Human Health =
50 ng/L
Hg in Sediment 220 1.82 23.01 54.76 14 (SQuiRT) 174
ng/g
Hg in Sediment
Porewater
12.5 0.5 2.67 3.98 14
Dry Fish Tissue Hg
(no liver included)
2,920 26.9 354.23 428.47 67 329.07 ng/g – 380
ng/g
Dry Fish MeHg (no
liver included)
2,860 25.2 328.69 307.79 67
4Dry Mink Fur Hg 7,670 4,180 6,258 1,278 4
4Dry Otter Fur Hg 6,330 2,070 NA NA 2
5Wet Wt. Otter Fur
Hg
417 NA NA NA 1
1 Dissolved acute criterion is 85% of total recoverable mercury.
2 Based on results from 2013 sampling, the total mercury concentrations for 2013 from water column samples are considered high estimates
as results did not meet acceptance limits for laboratory performance. A correction factor will be developed for the 2013 results following
QA/QC review of 2014 data
3 Indicates range of total mercury reported from ADEC (2012) Susitna Basin study from several species with minimum concentration in
Sockeye Salmon and maximum concentration in lake trout. (not an AWQS).
4 Fur samples were collected outside the study area (near the Sustina River between Indian River and Portage Creek) in 2014 and results
are considered provisional until the full quality assurance review is completed by mid-December 2014. Range of concentrations of Hg in
Mink combine results from fur and fur & pelt results.
5 River otter fur collected in the study area in 2014 and results are considered provisional until the full quality assurance review is
completed by mid-December 2014. A single sample consisting of 4 hairs provided a single result.
Susitna-Watana Hydroelectric Project Alaska Energy Authority
FERC Project No. 14241 Page 13 September 2014
10/16/2014 1
Initial Study Report Meeting
Study 5.7 Mercury Assessment and Potential for Bioaccumulation
October 16, 2014
(revised per errata November 14, 2014)
Prepared by Tetra Tech, Inc.
10/16/2014 2
Study 5.7 Objectives
•Summarize available and historic mercury information for the Susitna River
basin, including data collection from the 1980s Alaska Power Authority (APA)
Susitna Hydroelectric Project
•Characterize the baseline mercury concentrations of the Susitna River and
tributaries. This will include collection and analyses of vegetation, soil, water,
sediment pore water, sediment, piscivorous birds and mammals, and fish
tissue samples for mercury
•Utilize available geologic information to determine if a mineralogical source
of mercury exists within the inundation area
•Map mercury concentrations of soils and vegetation within the proposed
inundation area. This information will be used to develop maps of where
mercury methylation may occur
•Use the water quality model to predict where in the reservoir conditions
(pH, dissolved oxygen [DO], turnover) are likely to be conducive to MeHg
formation
•Use modeling to estimate MeHg concentrations in fish.
•Assess potential pathways for MeHg to migrate to the surrounding
environment
•Coordinate study results with other study areas, including fish, instream
flow, and other piscivorous bird and mammal studies
10/16/2014 3
Study 5.7 Components
•Vegetation (ISR Part A, Section 4.2.1; pg 3)
•Soil (ISR Part A, Section 4.2.2; pg 3)
•Water (ISR Part A, Section 4.2.3; pg 4)
•Sediment and Sediment Porewater (ISR Part A, Section
4.2.4; pg 7)
•Piscivorous Birds and Mammals (ISR Part A, Section 4.2.5;
pg 8)
•Fish Tissue (ISR Part A, Section 4.2.6; pg 9)
10/16/2014 4
Study 5.7 Variances
•Table 5.7-5 in Study Plan Section 5.7.4.2.3 summarizes the proposed water sampling
locations for mercury analysis in water. PRM 225.5 (Susitna near Cantwell) could not
be sampled due to limited access by helicopter. The sample site was relocated to PRM
235.2 (Susitna River adjacent to Oshetna Creek). See subsection 4.2.3.4 in this ISR.
•RSP Section 5.5.4.4.2 indicated that water samples would be collected at three
locations along each transect for mainstem samples. Water samples were collected
from just one position in the river due to limited access by wading at PRM 235.2
(Susitna River adjacent to Oshetna Creek) and 187.2 (Susitna at Watana Dam site).
See subsection 4.2.3.4 in this ISR.
•Study Plan Attachment 5-1 indicated that an Ekman dredge or modified Van Veen
grab sampler would be deployed from a boat; however, this approach was impractical
and other approaches (wading) were employed (as identified in the QAPP). See
subsection 4.2.4.1 in this ISR.
•EPA Method 1631 recommends digestion of mineral soil with aqua regia and oxidized
with bromine monochloride (BrCl) to extract mercury from samples for analyses. The
soil samples collected in 2013 contained a significant fraction of peat and organic
material mixed with soil. For these types of organic soils, EPA recommends digestion
with HNO3/H2SO4 digestion before using BrCl. Given the soil was a mix of organic
and inorganic components, each sample was split and analyzed them using both
digestion methods, giving two analytical results for each sample.
10/16/2014 5
Study 5.7 Variances
•RSP Section 5.7.4.6.1 indicated seven to ten of each target species of fish
would be collected; however, additional fish were collected for some species
(Arctic grayling and round whitefish). The Study Plan also indicated that only
adult fish would be collected; however, some juvenile specimens were
incidentally collected. While most were released, if a juvenile fish was
captured accidentally and died, it was analyzed.
•The Study Plan indicated that all fish would be speciated; however, two fish
could not be successfully speciated. Also, it was not possible to successfully
extract otoliths from all fish captured; however, sufficient otolith data is
available from other studies.
•The Study Plan required determination of the sex and sexual maturity of the
fish, however, determination of gender for the fish proved to be problematic
in the field, and the sex of only 12 fish was determined. The proposed field
collection period for fish was from August to September; however, the
sample period was extended into October to obtain sufficient samples.
Polyethylene sheets rather than Teflon sheets were used for the fish when
placed in the sample bag. See subsection 4.2.6.1.
10/16/2014 6
Study 5.7 Summary of Results in ISR
(ISR Study 5.7, Part A – Section 5)
•Samples collected in 2013 include:
•Vegetation and soil samples collected from ten locations at five
different sites within each location.
•Water quality samples collected from 17 baseline sites and 7 focus
areas.
•Sediment and sediment porewater samples collected from 4 sites.
•60 67 fish tissue samples collected including tissues from trout,
longnose sucker, Dolly Varden, Arctic grayling, slimy sculpin, burbot,
and whitefish.
•2013 Lab results for mercury concentrations in vegetation, soil, water,
sediment, sediment porewater, and fish tissue were not received in time
for inclusion in the ISR. Results have been QA/QCd and will be included in
the USR.
10/16/2014 7
Study 5.7 Summary of Results since ISR
(Evaluation of Continued Mercury Monitoring Beyond 2014, September 2014 Tech Memo)
•Average concentration of dissolved mercury in the water column was 1.06
ng/L from 2013 results . This concentration is substantially lower than the
criterion for chronic effects.
•The average sediment mercury result was 23.01 ng/g . One result from
mercury in sediment (220 ng/g) exceeded the recommended SQuiRT
Threshold from a total of 13 14 results.
•Background information for mercury in fish tissue was acquired from
recent fish tissue analysis by ADEC with results ranging from 29.07ng/g
(total mercury in Sockeye salmon) – 380.0 ng/g (total mercury in lake
trout) in the Susitna Drainage (ADEC 2012). The average concentration
among several species of fish sampled in 2013 from the Susitna drainage
was within the range described by ADEC.
10/16/2014 8
Study 5.7 Summary of Results since ISR Cont.
(Evaluation of Continued Mercury Monitoring Beyond 2014, September 2014 Tech Memo)
1 Dissolved acute criterion is 85% of total recoverable mercury.
2 Based on results from 2013 sampling, the total mercury concentrations for 2013 from water column samples are considered high estimates as results did not
meet acceptance limits for laboratory performance. A correction factor will be developed for the 2013 results following QA/QC review of 2014 data
3 Indicates range of total mercury reported from ADEC (2012) Susitna Basin study from several species with minimum concentration in Sockeye Salmon and
maximum concentration in lake trout. (not an AWQS).
4 Fur samples were collected outside the study area in 2014 and results are considered provisional until the full quality assurance review is completed by mid-
December 2014. Range of concentrations of Hg in Mink combine results from fur and fur & pelt results.
5 River otter fur collected in the study area in 2014 and results are considered provisional until the full quality assurance review is completed by mid-December
2014. A single sample consisting of 4 hairs provided a single result.
Sample Matrix Maximum
(ng/g dry or ng/L
wet)
Minimum
(ng/g dry or ng/L
wet)
Mean
(ng/g dry or ng/L
wet)
Standard Deviation No. of Observations Criteria or Threshold
Hg in Dry Vegetation 16.1 6.71 9.16 1.90 50
MeHg in Dry Vegetation 5.15 2.54 3.17 0.53 50
Hg in Dry Organic Matter 129 26.8 58.25 20.04 55
Hg in Dry Soil 119 27.1 60.46 21.07 55
MeHg in Dry Soil 4.34 0.096 0.61 0.89 55
1Dissolved Hg in Water
Column
58.7 0.5 (DL) 1.06 4.21 375 Acute = 2,040 ng/L
Total Recoverable Hg in
Water Column
See note 2 See note 2 See note 2
See note 2
See note 2
Aquatic Life:
Chronic = 12 ng/L
Acute = 2,400 ng/L
Human Health = 50 ng/L
Hg in Sediment
(4 Sites)
220 1.82 23.01 54.76 14 (SQuiRT) 174 ng/g
Hg in Sediment
Porewater (4 Sites)
12.5 0.5 2.67 3.98 14
Dry Fish Tissue Hg
(no liver included)
2,920 26.9 354.23 428.47 67 329.07 ng/g – 380 ng/g
Dry Fish MeHg
(no liver included)
2,860 25.2 328.69 307.79 67
4Dry Mink Fur Hg 7,670 4,180 6,258 1,278 4
4Dry Otter Fur Hg 6,330 2,070 NA NA 2
5Wet Wt. Otter Fur Hg 417 NA NA NA 1
10/16/2014 9
Study 5.7 Summary of Results since ISR Cont.
(Evaluation of Continued Mercury Monitoring
Beyond 2014 Tech Memo)
Mercury Pathways Analysis
Sediment Hg = 23.01 ng/g
Porewater Total Hg= 2.67 ng/L
Water Column Dissolved Hg= 1.06 ng/L
Water Column Total Hg= 25.55 ng/L
(Provisional Data; Under Review)
Dry soil Hg = 60.46 ng/g
Dry Soil MeHg =0 .61 ng/g
Dry Organic Matter Hg= 58.25 ng/g
Dry Vegetation Hg= 9.16 ng/g
Dry Vegetation MeHg= 3.17 ng/g
Dry Fish Hg= 354.23 ng/g
Fish MeHg= 328.69 ng/g
Dry Mink Fur Hg = 6,258 ng/g (4 samples)
Dry Otter Fur Hg = NA (1 sample)
(Note: Not in study area)
Allocthonous Input
10/16/2014 10
7.1.2.1. Extension of Mercury Water Quality Sampling
•“Estimated” laboratory results call for more total mercury sampling in 2014
(change from RSP Section 5.7.4.2.3.)
•Parameters affected: total metals (except Ca and Mg), total mercury,
total phosphorus, total Kjeldahl nitrogen, total nitrate+nitrite-nitrogen,
and dissolved aluminum
7.1.2.2. In-Accessible Sediment Sampling Locations
•Six sediment samples (planned for 2013) located on CIRWG lands will be
collected for mercury analysis in 2014 (change from RSP Section 5.7.4.2.4.)
7.1.2.3. Modifications to Sediment Sampling Methods
•Originally planned to use a Van Veen sampler lowered from a boat (RSP
Section 5.7.4.2.4.), but a boat in the upper river has proven impractical
•Back to sediment sampling methods used in 2013 (ISR 5.5; Section 4.5)
AEA Proposed Modifications to Study 5.7 in ISR
(ISR Study 5.7, Part C – Section 7.1.2)
10/16/2014 11
7.1.2.4. Modification of Sediment, Water, and Porewater Sampling Locations
•Sample locations for water, sediment, and sediment porewater sites in Upper
River were modified slightly due to lack of access
•Available data shows river as well mixed and water quality to have little
variability
7.1.2.5. Modification of Fish Tissue Sampling
•Previous fish sampling in Upper Susitna Basin indicate humpback whitefish to
be rare, they have been taken out of the study
•Rainbow trout and stickleback not found in inundation zone and also take out
of the study
•Round whitefish were added to the study (all changes from RSP Section
5.7.4.6.1. and 5.5.4.7.)
•Only older aged burbot were caught, no younger (no additional sampling
planned)
AEA Proposed Modifications to Study 5.7 in ISR
(ISR Study 5.7, Part C – Section 7.1.2) (Continued)
10/16/2014 12
AEA Proposed Modifications to Study 5.7 in ISR
(ISR Study 5.7, Part C – Section 7.1.2)
7.1.2.6. Modification of Piscivorous Wildlife Tissue Sampling
•Initial evaluation of the potential for bioaccumulation will focus on the
aquatic environment
•Samples for mercury study collected in 2014 only from water and
sediment for analysis of mercury and methylmercury
•Collection of tissue samples from piscivorous wildlife for mercury analysis
described for various species groups in Studies 10.11, 10.14, 10.15, and
10.16 is being consolidated under Study 5.7
•Very few samples of river otter or mink hair have been attained (trappers
and hair snags)
•Last resort would be to hire trappers for lethal collection of animals in
study area for mercury analysis
10/16/2014 13
AEA Proposed Modifications to Study 5.7 in ISR
(ISR Study 5.7, Part C – Section 7.1.2) (Continued)
7.1.2.6. Modification of Piscivorous Wildlife Tissue Sampling
•Collecting feathers from vacated nests of piscivorous birds was found to be
unproductive
•Study 10.14 added three tasks to assist Study 5.7: provide info on
distribution, abundance, foot habits and diet of piscivorous raptors,
collect feather samples from active nests after nesting season for
characterization of mercury levels, and provide information on the
effects of methylmercury on piscivorous raptors
•Possible use of contractor to capture live Bald Eagles to obtain blood
and feather samples for mercury analysis
•Collecting feathers from vacated nests of piscivorous waterbirds (Study
10.15) was unsuccessful
•Possible hiring of highly skilled specialty contractor to do live tissue
sampling for mercury analysis
•Single target species of piscivorous landbird (Belted Kingfisher) because the
species is rare and no nests were found
•No longer considered suitable target species for mercury analysis
10/16/2014 14
Current Status and Steps to Complete Study 5.7
•In 2013, vegetation, soil, and fish tissue mercury sampling was completed
and referenced in the ISR Study 5.7 Section 5.
•Planned activities for 2014 as referenced in ISR Study 5.7, Part C- Section 7.1
that have been completed include
•Collection of sediment samples at the six remaining sites located on
CIRWG lands (RSP Section 5.7.4.2.4)
•Limited winter water quality sampling occurred in January and March
of 2014 (RSP Section 5.7.4.2.3)
•Summer monthly water sampling from June to September 2014 (see
ISR Section 5.5 for details)
•Pathway analysis has not yet been completed and is the next major
component of this study that will determine potential sources for
bioaccumulation.
•Based upon its preliminary review of the mercury results measured in each
of the media, AEA is not proposing any additional sampling for mercury in
2015.
10/16/2014 15
Potential Mercury Pathway in a Mature Reservoir
10/16/2014 16
Licensing Participants Proposed Modifications to Study 5.7?
•Agencies
•CIRWG members and Ahtna
•Public