OCS Study MMS 2004-032

ANIMIDA Task 5

 Sources, Concentrations and Dispersion Pathways for 

Suspended Sediment in the Coastal Beaufort Sea

Final Report Submitted to

 U.S. Department of Interior

Minerals Management Service

Anchorage, Alaska 

May 2004

Submitted by

John H. Trefry, Robert D. Rember, Robert P. Trocine 

Florida Institute of Technology, Melbourne, Florida

Mark Savoie, Kinnetics Laboratories, Inc., Anchorage, Alaska

Contract No. 143501-99-CT-30998, TO 10905

 U.S. Department of the Interior

 Minerals Management Service

 Alaska Outer Continental Shelf Region 
ii

ANIMIDA Task 5

 Sources, Concentrations and Dispersion Pathways for 

Suspended Sediment in the Coastal Beaufort Sea

Final Report

Submitted by:

John H. Trefry, Robert D. Rember, Robert P. Trocine 

Department of Marine & Environmental Systems

Florida Institute of Technology

150 West University Boulevard, Melbourne, Florida, 32901

Mark Savoie, Kinnetics Laboratories, Inc. 

403 West Eighth Avenue, Anchorage, Alaska, 99501

(e-mail address for corresponding author: jtrefry@fit.edu)

This study was funded by the U.S. Department of the Interior, 

Minerals Management Service (MMS), Alaska Outer Continental Shelf Region, 

Anchorage, Alaska, under Contract No. 1435-01-99-CT-30998, TO 10905, 

as part of the MMS Alaska Environmental Studies Program.

May 2004

The opinions, findings, conclusions, or recommendations expressed in this report 

or product are those of the authors and do not necessarily reflect the views of the 

U.S. Department of the Interior, not does mention of trade names or commercial 

products constitute endorsement or recommendation for use by the Federal 

Government.
iii

Table of Contents

 Page

EXECUTIVE SUMMARY.................................................................... 1

1.0 INTRODUCTION ....................................................................... 5

2.0 METHODS ................................................................................ 8

2.1 Source Samples ................................................................... 8

2.2 Under-Ice Sampling .............................................................. 8

2.2.1 Navigation and Logistics ............................................. 8

2.2.2 Offshore Hydrographic Profile Measurements ................... 8

2.2.3 Suspended Sediment ................................................... 9

2.3 Sampling during Open-Water Periods .......................................... 9

2.4 Laboratory Analyses .............................................................. 10

2.4.1 Particulate Organic Carbon .......................................... 10

2.4.2 Trace and Major Metals in Suspended Sediment ................. 10

2.4.3 Scanning Electron Microscopy ...................................... 11

2.5 Quality Assurance and Quality Control ....................................... 12

2.5.1 Sample Tracking Procedure ....................................... 12

2.5.2 Quality Control Measurements for Analysis ..................... 12

2.5.3 Instrument Calibration ................................................ 13

2.5.4 Matrix Spike Analysis ............................................... 13

2.5.5 Duplicate Sample Analysis ........................................ 13

2.5.6 Procedural Blank Analysis .......................................... 13

2.5.7 CRM and SRM Analysis ............................................ 14

3.0 RESULTS AND DISCUSSION ........................................................ 16

3.1 River Sources of Suspended Sediment ......................................... 16

3.1.1 River Breakup and Summer: 2001 ................................. 18

3.1.1.1 Sagavanirktok River ........................................ 18

3.1.1.2 Kuparuk River ................................................ 20

3.1.1.3 Colville River ................................................ 22

3.1.2 River Breakup and Summer: 2002 ................................. 23

3.1.2.1 Sagavanirktok River ........................................ 23

3.1.2.2 Kuparuk River ............................................... 26

3.1.2.3 Colville River ................................................ 27

3.2 Composition of River Suspended Sediment .................................... 28
iv

Table of Contents (continued)

 Page

3.3 River Transport of Suspended Sediment, Particulate Metals and 

Particulate Organic Carbon to the Coastal Beaufort Sea ............... 41

3.4 River Water Flow Under Ice ................................................... 45

3.5 Ice Cores ........................................................................... 63

3.6 Suspended Sediment in Waters of the Coastal Beaufort Sea ............... 66

3.7 Sediment Accumulation ......................................................... 81

4.0 SUMMARY AND CONCLUSIONS ................................................ 83

5.0 REFERENCES ........................................................................... 85 

6.0 LIST OF APPENDICES (Appendices on CD) .................................... 87
v

List of Tables

 Page

Section 2

Table 2-1: Summary of instrumental methods and method detection limits 

(MDL) for metal analysis of suspended sediment .................. 12

Table 2-2: Data quality objectives and criteria ........................................ 14

Table 2-3: Results for reference materials ............................................. 15

Section 3 

Table 3-1: Locations of river sampling sites ............................................ 17 

Table 3-2: Concentrations of metals and organic carbon in suspended sediment

from the Sagavanirktok, Kuparuk and Colville rivers during 

June 2001 .............................................................. 30 

Table 3-3: Concentrations of metals and organic carbon in suspended sediment

from the Sagavanirktok and Kuparuk rivers during June 2002.. 31

Table 3-4: Correlation coefficients for particulate trace metals and particulate 

organic carbon in the Sagavanirktok River during June 2001 ... 37

Table 3-5: Amounts of suspended sediment, particulate metals and particulate

organic carbon carried by the Sagavanirktok, Kuparuk and 

Colville rivers to the coastal Beaufort Sea .......................... 42

Table 3-6: Concentrations of particulate trace metals and particulate organic carbon

in the Sagavanirktok, Kuparuk and Colville rivers during June 

2001 ..................................................................... 43

Table 3-7: Trends in concentrations of suspended sediment in the coastal Beaufort

Sea as a function of wind and sea ice conditions .................. 71

Table 3-8: Summary data for total suspended sediment for all stations in the 

ANIMIDA study area and for a subset of stations in the area of 

Northstar Island ........................................................ 73

Table 3-9: Means and standard deviations for total suspended sediment, turbidity 

and concentrations of metals and particulate organic carbon for

suspended sediment collected from the coastal Beaufort Sea

during August 2000 ................................................... 75

Table 3-10: Means and standard deviations for total suspended sediment, turbidity 

and concentrations of metals and particulate organic carbon for

suspended sediment collected from the coastal Beaufort Sea

during August 2001 ................................................... 76

Table 3-11: Means and standard deviations for total suspended sediment, turbidity 

and concentrations of metals and particulate organic carbon for

suspended sediment collected from the coastal Beaufort Sea

during August 2002 ................................................... 77
vi

List of Figures

 Page

Executive Summary

Figure ES-1: The Sagavanirktok River at a bridge near the Prudhoe Bay Operations 

Center (a) flowing on May 22, 2002 and (b) re-frozen on 

May 29, 2002 .......................................................... 1

Figure ES-2: Water Discharge, turbidity and concentrations of total suspended 

solids in the Sagavanirktok River near the Prudhoe Bay 

Operations Center during May-June 2001 and 2002 ............. 2 

Figure ES-3: Vertical profiles for salinity and transmissivity along a transect 

seaward of the Sagavanirktok River for May 27, 2002 .......... 3

Section 2

Figure 1-1: Map showing the western portion of the coastal Beaufort Sea 

with inset maps of Alaska, the oil production site at 

Northstar Island and a possible future drilling site 

at Liberty Prospect .................................................... 6

Section 3

Figure 3-1: Map showing locations of sampling sites in the Sagavanirktok, Kuparuk 

and Colville rivers with inset map showing study area ............ 17 

Figure 3-2: Sagavanirktok River on May 25, June 3, June 5, and June 11, 2001 

at bridge near Prudhoe Bay Operations Center ..................... 18

Figure 3-3: Water discharge and concentrations of total suspended solids 

in the Sagavanirktok River at PBOC during June 2001 ........... 19

Figure 3-4: Conductivity for water from the Sagavanirktok River for June 

2001 near Prudhoe Bay Operations Center, U.S. Geological 

Survey gauge, and at mile 401 on the Dalton Highway .......... 20

Figure 3-5: Kuparuk River causeway/bridge shown under water during peak flow 

on June 11, 2001 and then high and dry and rebuilt 

on June 20, 2001 ................................................................ 20 

Figure 3-6: Concentrations of total suspended solids and water discharge 

for the Kuparuk River for June 2001 ............................... 21

Figure 3-7: Conductivity for water from the Kuparuk and Sagavanirktok rivers 

for June 2001 .......................................................... 21

Figure 3-8: Colville River at Monument 1 during peak flow on June 9, 2001 

and at lower flow on June 20, 2001 ................................. 22 

Figure 3-9: Water flow and concentrations of total suspended solids for the 

Colville River during June 2001 .................................... 22

Figure 3-10: Conductivity for water from the Colville River and the 

Sagavanirktok River at the Prudhoe Bay Operations Center

for June 2001 ........................................................... 23 

Figure 3-11: Sagavanirktok River flowing on May 22, frozen on May 29, and 

flowing again on May 31 and June 12, 2002 at bridge near 

Prudhoe Bay Operations Center ...................................... 24
vii

 Page

Figure 3-12: (a) Concentrations of total suspended solids and turbidity 

for the Sagavanirktok River during May-June 2002. 

(b) Water discharge in Sagavanirktok River for June 2002 ..... 25

Figure 3-13: Conductivity in the Sagavanirktok, Kuparuk and Colville rivers 

during May-June 2002 ............................................... 26

Figure 3-14: Kuparuk River during flood period in May 2002 ......................... 26

Figure 3-15: Water flow and concentrations of total suspended solids and 

turbidity for the Kuparuk River during May-June 2002 ......... 27

Figure 3-16: Water flow and concentrations of total suspended solids in 

the Colville River during May-June 2002 .......................... 27

Figure 3-17: Colville River after the spring flood during June 2002 .................... 28

Figure 3-18: Scanning electron micrograph showing suspended sediment 

collected from the Sagavanirktok River on June 9, 2001 ........ 29

Figure 3-19: Scanning electron micrograph showing suspended sediment collected

from the Colville River on June 14, 2001, during peak flow ... 29

Figure 3-20: Concentrations of aluminum versus calcium for suspended sediment 

from the Sagavanirktok, Colville and Kuparuk rivers 

during June 2001 and May-June 2002 .............................. 32 

Figure 3-21: Concentrations of aluminum versus potassium and magnesium for

suspended sediment from the Sagavanirktok, Colville and 

Kuparuk rivers during June 2001 and May-June 2002 ............ 33

Figure 3-22: Fraction of different rock types that were chemically weathered to 

produce the observed concentrations of dissolved major 

elements in the Sagavanirktok River during peak and 

off-peak flow in 2001 .................................................. 35

Figure 3-23: Concentrations of copper, lead, zinc, iron, barium and particulate 

organic carbon for suspended sediment from the 

Sagavanirktok River during June 2001 .............................. 36

Figure 3-24: Concentrations of aluminum versus barium for suspended sediment 

from the Sagavanirktok, Colville and Kuparuk rivers 

during June 2001 and May-June 2002 ................................ 38 

Figure 3-25: Concentrations of aluminum versus iron for suspended sediment 

from the Sagavanirktok, Colville and Kuparuk rivers 

during June 2001 and May-June 2002 ...........................,.. 38

Figure 3-26: Concentrations of aluminum versus lead and arsenic in suspended

sediment from the Sagavanirktok, Kuparuk and Colville 

rivers for June and August 2001 and May-June 2002 ............ 40

Figure 3-27: Concentrations of total suspended solids versus particulate organic 

carbon for river suspended sediment ............................... 41

Figure 3-28: Aerial photographs from June 11, 2001 showing (a) Endicott Island 

with incoming flow from the Sagavanirktok River and 

(b) incoming water from the Kuparuk River being diverted 

by ice roads to Northstar Island ..................................... 45

Figure 3-29: Vertical profiles for salinity, temperature and transmissivity for 

station AN03 during under ice sampling in June 2001 .......... 46
viii

 Page

Figure 3-30: Map showing under ice and river sampling locations with 

concentrations of suspended sediment in river water and 

in the surface layer of river water under the ice for 

June 8 and 9, 2001 .................................................. 47

Figure 3-31: Vertical profiles for salinity along a transect seaward of the 

Sagavanirktok River delta for June 9 and 11, 2001 .............. 48

Figure 3-32: Vertical profiles for temperature along a transect seaward of the

Sagavanirktok River delta for June 9 and 11, 2001 ............. 49

Figure 3-33: Vertical profiles for transmissivity along a transect seaward of the

Sagavanirktok River delta for June 9 and 11, 2001 ............. 50

Figure 3-34: Vertical profiles for salinity, temperature and transmissivity along a

transect seaward of the Kuparuk River delta for June 10, 2001 .. 52

Figure 3-35: Map showing under ice and river sampling locations with

concentrations of suspended sediment in river water and in the

surface layer of river water under the ice for June 2002 ........... 54

Figure 3-36: Vertical profiles for salinity along a transect seaward of the 

Sagavanirktok River delta for May 27 and June 4, 2002 ......... 55

Figure 3-37: Vertical profiles for temperature along a transect seaward of the

Sagavanirktok River delta for May 27 and June 4, 2002 ......... 56

Figure 3-38: Vertical profiles for transmissivity along a transect seaward of the 

Sagavanirktok River delta for May 27 and June 4, 2002 ......... 57

Figure 3-39: Bar graphs showing salinity and concentrations of total suspended 

solids for under ice samples from May 26, 2002 

and June 4, 2002 ........................................................ 58

Figure 3-40: (a) Concentrations of aluminum versus iron in suspended sediment

from area rivers and under ice in the Beaufort Sea during 

spring floods and (b) concentrations of iron in suspended 

sediment from under ice during May-June 2002 for stations at

Northstar Island and the outflow of the Sagavanirktok River .... 59 

Figure 3-41: (a) Concentrations of aluminum versus barium in suspended sediment

from area rivers and under ice in the Beaufort Sea during

spring floods and (b) concentrations of barium in suspended

sediment from under ice during May-June 2002 for stations 

at Northstar Island and the outflow of the Sagavanirktok River . 61

Figure 3-42: (a) Concentrations of aluminum versus lead in suspended sediment

from area rivers and under ice in the Beaufort Sea during spring

floods and (b) concentrations of lead in suspended sediment from

under ice during May-June 2002 for stations at Northstar 

Island and the outflow of the Sagavanirktok River ............... 62

Figure 3-43: Schematic profiles showing amount of sediment suspended in ice cores

collected during 2000 and 2002 with picture showing the ice

coring process .......................................................... 64
ix

 Page

Figure 3-44: Schematic representation of the release of sediment from melting 

sea ice ................................................................... 65

Figure 3-45: Relationship between concentrations of total suspended solids and

laboratory turbidity .................................................... 66

Figure 3-46: Relationship for concentrations of total suspended solids versus 

laboratory turbidity and in situ turbidity ........................... 67

Figure 3-47: Map showing sampling stations in the ANIMIDA study area with inset

maps of Alaska, the oil production site at Northstar Island 

and a possible future drilling site at Liberty Prospect ............ 68

Figure 3-48: Vertical profiles for turbidity at selected sites in the area of Northstar

Island during August 2001 ........................................... 69

Figure 3-49: Vertical profiles for turbidity at selected locations in the area of Liberty

Prospect ................................................................. 70 

Figure 3-50: Towing package with conductivity, temperature and turbidity sensors .. 71

Figure 3-51: Data for turbidity during summer 2001 for horizontal transects upcurrent

and down current at Northstar Island ................................ 72

Figure 3-52: Emplacement of concrete armoring on Northstar Island during 

Summer 2000 ............................................................ 74

Figure 3-53: Concentrations of Al versus total suspended solids and particulate 

organic carbon for suspended sediment from the coastal 

Beaufort Sea ............................................................. 78

Figure 3-54: Concentrations of aluminum versus iron, barium, chromium and zinc 

for suspended sediment from the coastal Beaufort Sea during 

1999, 2000, 2001 and 2002 ........................................... 79

Figure 3-55: Concentrations of aluminum versus copper, cadmium, lead and arsenic

for suspended sediment from the coastal Beaufort Sea during 

1999, 2000 and 2001 ................................................... 80

Figure 3-56: Sedimentation rates for the coastal Beaufort Sea based on data for 137Cs

and excess 210Pb ........................................................ 82

 

 

 

 
1

EXECUTIVE SUMMARY

The Arctic Nearshore Impact Monitoring in the Development Area (ANIMIDA) Program 

was developed to monitor potential environmental changes related to oil and gas

development in the Beaufort Sea with a special focus on the Northstar and Liberty

developments. A variety of biological and chemical studies were included in the

ANIMIDA Program. This report presents the results from study of suspended sediment. 

The study was designed to address the possibility that oil and gas activities might

increase levels of suspended sediment in the coastal Beaufort Sea. 

 

The concentrations and composition of suspended particles in the coastal Beaufort Sea 

directly influence a variety of important processes including the following: 

(1) Penetration of light in the water column and the rate of primary 

productivity. 

(2) Transport and fate of trace metals and organic substances in the water

column. 

(3) Adsorption of dissolved trace metals from seawater and partial control of 

concentrations of the more biologically available dissolved metals. 

To better understand the sources and distribution of suspended sediment as they relate to 

the diverse processes listed above, the goals for this Task 5 study included the following:

(1) Determine the amounts and composition of suspended sediment carried to 

the coastal Beaufort Sea by the Sagavanirktok, Kuparuk and Colville rivers.

(2) Determine the concentrations, distribution patterns, composition and fate of 

suspended particles in the coastal Beaufort Sea, especially in areas such as 

Northstar Island and Liberty Prospect where construction activities now or 

in the future may influence concentrations of suspended sediment. 

One goal of this effort was to understand the importance of river inputs and storm activity 

to the transport, distribution, composition and fate of suspended sediment in the coastal 

Beaufort Sea. In other words, natural processes and natural variations in levels of

suspended sediment must be understood before attempting to identify anthropogenic

perturbations. Field activities for this Task 5 study included sampling rivers during

spring breakup in May-June 2001 and 2002 (Figure ES-1), through ice sampling of the 

Beaufort Sea during spring floods (2001 and 2002) and sampling rivers and offshore 

waters during the open-water periods of June-August 2000, 2001 and 2002. 

 

Figure ES-1. The Sagavanirktok River at a bridge near the Prudhoe Bay Operations Center 

(a) flowing on May 22, 2002 and (b) re-frozen on May 29, 2002.

(a) (b)
2

Rivers are an important source of water and sediment to the study area during the period 

of spring runoff and on an annual basis. Determining the amounts and composition of 

river-borne suspended sediment was a key task during 2001 and 2002. The

Sagavanirktok River was sampled daily during late May and June and the other two

rivers were sampled every two to five days as logistics permitted. Samples of water and 

suspended sediment from the Sagavanirktok River also were collected at mile 401 on the 

Dalton Highway and at a gauging station maintained by the U.S. Geological Survey, 

about 100 miles south of Deadhorse (mile 327 on the Dalton Highway).

Concentrations of total suspended solids (TSS) in the Sagavanirktok River near the

Prudhoe Bay Operations Center (PBOC) increased from ~40 mg/L on June 1 when flow

began to 600 mg/L on June 12, 2001, and then decreased to ~30 mg/L by June 18 (Figure 

ES-2). During late July and August 2001, concentrations of TSS were ~2 mg/L. 

Concentrations of TSS followed similar trends for the Colville River with maximum

levels of about 600 mg/L on June 13, 2001. In contrast, concentrations of TSS reached 

peak values of only 60 mg/L in the Kuparuk River on June 10, 2001 and decreased to <5 

mg/L after June 16, 2001. Peak flow recorded for the Kuparuk River was about 600

m

3

/sec on June 12, 2001, decreasing to <50 m3/sec after June 28, 2001. During 2002, the 

same trend of increasing concentrations of TSS was observed; however, freezing

temperatures led to refreezing of the rivers and put a hiatus in the spring flood for the 

Sagavanirktok River (Figure ES-2). However, the dramatic two-day flood of the

Kuparuk River in 2002 occurred during the period prior to refreezing. 

6/1/01 6/8/01 6/15/01 6/22/01 

Water Discharge (m

3/s)

0

100

200

300

400

Total Suspended Solids (mg/L)

0

100

200

300

400

500

600

700

TSS 

Water Flow Calculated

Water Flow Measured

Sagavanirktok River 2001

 

05/20/02 05/27/02 06/03/02 06/10/02 06/17/02 

TSS (mg/L) and Turbidity (NTU)

0

50

100

150

200

250

300

350

400

Turbidity (NTU) 

TSS (mg/L)

Sagavanirktok River 2002

river froze

river re-melted

river flood begins

rain 

Figure ES-2. Water discharge (from U.S. Geological Survey), turbidity and concentrations of 

total suspended solids (TSS) in the Sagavanirktok River near the Prudhoe Bay 

Operations Center during May-June 2001 and 2002.

For the Sagavanirktok River, the calculated annual sediment transport was ~0.33 million 

metric tons for 2001, with ~87% of the annual transport of suspended sediment occurring 

during just 12 days in June. Total transport of suspended sediment by the Kuparuk River 

was 0.02 million metric tons for 2001 with ~90% of the annual sediment load of the river 

being carried during just three days in June. Previous estimates for the Colville River of 

5 million metric tons of sediment per year are supported by recent measurements during 

high flow. These natural inputs by rivers can be compared with ~1.6 million metric tons

of sand and gravel used to construct Northstar Island [(800,000 yd3 x 0.76 m3/yd3 x 2.6 
3

metric tons/m3 = 1.6 million metric tons). Coastal erosion also is an important source of 

sediment to the coastal Beaufort Sea, including the ANIMIDA study area. Estimates 

from previous studies state that coastal erosion may contribute sediment to the coastal 

Beaufort Sea at levels that are equal to or several times greater than inputs of sediment by 

rivers. Studies of erosion were not part of the ANIMIDA program; however, available 

results are reviewed in this report. 

Samples of suspended sediment also were collected under the ice, seaward of the rivers 

during the early days of spring runoff in 2001 and 2002 when the coastal Beaufort Sea 

was still ice covered. Concentrations of TSS averaged ~40 mg/L in a 2-m thick lens of 

freshwater immediately under the ice that extended >10 km offshore (Figure ES-3). The 

suspended sediment was very rich in fine-grained aluminosilicates as shown by the levels 

of Al and other metals in the particles. Metal/Al ratios in suspended particles collected 

under the ice showed that the composition of river-borne particles was similar to that 

found for bottom sediment. 

Figure ES-3. Vertical profiles for salinity and transmissivity (turbidity) along a transect

(distances on lower x axis) seaward of the Sagavanirktok River for May 27,

2002.

During the open-water period in 1999-2002, numerous vertical casts and horizontal tows 

in the water column were made throughout the coastal Beaufort Sea to measure turbidity, 

salinity, temperature and current speed and direction. Turbidity was measured by in situ 

turbidimeter, by laboratory turbidimeter using discrete samples and by 

filtration/gravimetry using discrete samples. 

The day-to-day turbidity and distribution of TSS in the coastal Beaufort Sea were

dependent on river flow, ice cover and sea state. In the protected, relatively quiescent 

waters under ice during most of the year, levels of TSS were low at a few tenths of a 

milligram per liter relative to average levels of ~40 mg/L in surface waters under the ice 

during the spring floods. During the brief open-water period, after the spring floods, 

concentrations of TSS were typically <20 mg/L and varied as a function of sea state and 

the presence of floating sea ice. Sea state was directly related to the strength and duration 

of winds. Concentrations of TSS increased to >50 mg/L during the summer only
4

following a period of several days with winds greater than 20 knots. In contrast, levels of 

TSS <2 mg/L were observed under conditions where calm water had prevailed for several 

days. This later condition was most likely to occur when floating ice dampened any wind 

effects. No significant deviations in levels of turbidity were observed adjacent to

Northstar Island during 2000-2002 while towing a turbidimeter-CTD package along 

transects at distances as close as 100-500 m from the island. 

The chemical composition of river suspended sediment was compared with results for 

bottom sediment to help identify possible anthropogenic inputs of suspended sediment or 

contaminant metals to the coastal environment. Differences in the elemental composition 

of suspended sediment were observed among rivers. The Colville River contained

greater amounts of particulate Al, Fe and trace metals relative to the more Ca-rich

particles of the Sagavanirktok River and the more organic carbon-rich particles of the

Kuparuk River. However, the metal/Al ratios for all elements, except Ca, were not

significantly different among rivers and bottom sediment from the coastal Beaufort Sea. 

Concentrations of trace metals also were determined for samples of suspended matter 

collected from the coastal Beaufort Sea. The fine-grained aluminosilicates suspended in 

the water column were enriched with Al and trace metals. However, concentrations of 

most metals in suspended sediment for 2000 and 2001 plotted within the 99% prediction 

intervals for metals versus Al that were developed using data for bottom sediment. Thus, 

in most instances, concentrations of trace metals associated with suspended particles were 

within the limits established for uncontaminated sediment. Suspended particles are 

potentially a more sensitive indicator of recent metal contamination than sediment

because the small amounts of suspended particles typically found in the water column 

lead to a larger relative enrichment of anthropogenic metal concentrations. This

sensitivity was demonstrated with several samples of suspended sediment that were

collected very near Northstar Island during construction in August 2000 and contained Pb 

at levels that were 20-50% above background. 

With respect to sedimentation, the ANIMIDA area appears to be a net erosional

environment at this time. Based on our observations, much of the large sediment load of 

the rivers is carried across the nearshore environment to deeper waters of the Beaufort 

Sea along a freshwater channel under the ice during spring or with summer and fall

storms. Therefore, sediment monitoring for contaminants must be coordinated with

measurements of radionuclides such as 137Cs, excess 210Pb, 234Th or 7Be that help ensure 

that samples are recent and not relict deposits.

Overall, no significant differences in concentrations of TSS that could be directly linked 

to oil and gas operations were observed in the ANIMIDA area. Periodic enhancement in 

levels of TSS in the coastal Beaufort Sea can be related to river runoff and resuspension

of bottom sediment by strong winds. Natural inputs of suspended sediment from runoff 

and erosion are large relative to any anthropogenic inputs of sediment. 

 
5

1.0 INTRODUCTION

The Arctic Nearshore Impact Monitoring in the Development Area (ANIMIDA) Program 

was developed to monitor potential environmental changes related to oil and gas

development in the Beaufort Sea with a special focus on the Northstar and Liberty

developments. This report presents the results from study of suspended sediment. The 

study was designed to address the possibility that oil and gas activities might enhance 

levels of suspended sediment in the coastal Beaufort Sea. Suspended sediment were 

collected from three area rivers and an area of coastal Beaufort Sea that encompassed the 

Northstar and Liberty developments (Figure 1-1). 

The concentrations and composition of suspended particles in the coastal Beaufort Sea 

directly influence a variety of important processes including the following: (1) the

penetration of light in the water column and thus the rate of primary productivity, (2) the 

transport and fate of trace metals and organic substances within the water column and the 

ANIMIDA study area, and (3) adsorption of dissolved trace metals and organic

substances from seawater and, thus, partial control of the concentrations of the more

biologically available dissolved fraction. The chemical and mineralogical compositions 

of suspended particles also provide a sensitive tracer of contaminant inputs and the

cycling of organic carbon. During Phase 1 (1999-2000) of the ANIMIDA Program

(Boehm et al., 2001) a good overview of the distribution and composition of suspended 

particles in coastal water was developed. The key conclusions of that work are as

follows: (1) after the spring runoff from the rivers subsides, the concentrations and

distribution of suspended sediment during the open-water season appear to be a function 

of wind conditions, water currents and water depth, and (2) the composition of suspended 

particles during the open-water season appears to match that of river suspended sediment 

and the fine-grained fraction of bottom sediment.

Based on the results of the suspended sediment component of the Phase 1 effort, several 

goals were established for the Task 5 of the Phase 2 study (2000-2002) that specifically 

focus on suspended sediment. These goals include the following: 

(1) Determine the annual amount of suspended sediment carried to the

coastal Beaufort Sea by the Colville, Kuparuk and Sagavanirktok

rivers.

(2) Determine the major element, trace element and organic carbon

content of river-borne particles.

(3) Continue to develop a picture of the concentrations, distribution

patterns and composition of suspended particles in the coastal

Beaufort Sea.

(4) Monitor the distribution and composition of suspended particles in the 

area of Northstar Island during the period of start-up and continuing 

operation.
6

Figure 1-1. Map showing the western portion of the coastal Beaufort Sea with inset maps of

Alaska, the oil production site at Northstar Island and a possible future drilling site 

at Liberty Prospect. The ANIMIDA study focused mainly on the area shown in the 

shaded box. 

(5) Identify the fate of river-borne suspended sediment in the coastal

Beaufort Sea.

One underlying theme in these stated goals is that the natural process and natural 

variations in levels of suspended sediment must be well understood before attempts to 

identify anthropogenic perturbations can be successful. 

Coastal erosion also is an important source of sediment to the coastal Beaufort Sea. 

Reimnitz et al. (1988) calculated an annual sediment yield from erosion of about 5

million tons along a 200-km stretch of the coast from Prudhoe Bay to Drew Point (at the 

western boundary of the map in Figure 1-1). Reimnitz et al. (1988) further estimated that 

this level of sediment input was about seven times greater than inputs from rivers. 

However, they calculate a value for river input that is about seven times lower than

Study Area

P1

.

 

..P1

. E1
7

reported by Arnborg et al. (1967). Even with the higher value for river input of sediment, 

the two processes appear to be, at minimum, equivalent. 

This report will focus on the concentrations and composition of suspended sediment in 

the following three aspects of the system:

(1) Source rivers.

(2) Under-ice flow into the coastal Beaufort Sea during spring breakup. 

(3) Open-water period in the coastal Beaufort Sea. 

Concentrations of dissolved components along these same pathways are presented in 

Trefry et al. (2004). Data for dissolved components are introduced to this Task 5 report 

only as pertinent to discussion of the results for suspended sediment. 
8

2.0 METHODS

2.1 Source Samples

Water samples for suspended sediment were collected from the Sagavanirktok, Kuparuk 

and Colville Rivers in 1-L, acid-washed, low-density, polyethylene bottles (LDPE). 

Some samples were obtained by wading into the river, waiting until disturbed sediment 

was washed down stream, and then opening an acid-washed 1- or 2-L LDPE bottle below 

the surface of the water. When the bottle was full, it was sealed beneath the surface,

retrieved, placed in a plastic bag, labeled and stored in a cooler for return to the on-site 

laboratory facilities to be filtered. During June 2001 and May-June 2002, samples from 

the Sagavanirktok and Kuparuk rivers were collected using a polyvinyl chloride (PVC) 

water sampler that held acid-washed, LDPE bottles and could be lowered from one of the 

bridges across the river. 

2.2 Under-Ice Sampling

2.2.1 Navigation and Logistics

Two snowmobiles equipped with freight sleds were used to transport personnel and

sampling gear from the Prudhoe Bay Seawater Treatment Plant (STP) to the sampling 

stations. Due to the hazardous nature and potential of being cutoff from land while 

working offshore during river breakup conditions, emergency survival gear,

communication equipment, emergency position indicating radiobeacon (EPIRB), and

other safety equipment were included on each field trip. A portable hand-held global 

positioning system (GPS) was used for positioning and relocation of sampling stations. 

Stations were spaced ~1.5 km apart extending from the leading edge of the river overflow 

plume offshore in a northerly direction with additional stations located perpendicular to 

the main transect for the Sagavanirktok River plume in both 2001 and 2002. 

Documentation at each station included station logs and field notes with date, time,

position, sampling information, and other observations including 35-mm and digital

photographs, and video recordings of sampling activity.

2.2.2 Offshore Hydrographic Profiles

To obtain hydrographic profiles and seawater samples at each offshore station, holes

were drilled in the ice using a gasoline-powered ice-auger equipped with a 25-cm 

diameter auger bit. Measurements were then made of the bottom depth with a sounding 

line and ice thickness with a graduated rod and recorded in the field logs. Hydrographic 

profiles were measured in situ with a Sea-Bird® Electronics, Inc. SEACAT SBE-19 

conductivity, temperature, and depth (CTD) recorder. The SBE-19 was configured to

measure and internally record temperature, conductivity, transmissivity, and pressure

once every half-second while being lowered and raised through the water column. The 

transmissivity sensor was a 25-cm path length transmissometer manufactured by Sea

Tech®, Inc. The CTD was equipped with a submersible profiling pump system, capable 

of maintaining flow across the sensors, even during a slow cast rate in shallow water. 
9

Data from the CTD were uploaded onto a portable field computer upon returning back to 

the STP each day. Salinity, sigma-t (density), and depth were determined during post 

processing from the conductivity, temperature, and pressure measurements. 

The SEACAT SBE-19 CTD was factory calibrated prior to each field season and rechecked in the field during each survey. In-field calibration checks involved comparison 

against a graduated line for depth measurements, thermometer readings for temperature, 

collection of Quality Control (QC) samples for salinity, and a zero and full-scale linear 

calibration for the transmissometer. Field QC samples were analyzed in the laboratory 

and then compared against the in situ recordings. In addition, duplicate CTD casts were 

performed at select stations to determine instrument repeatability and field sampling

variability.

2.2.3 Suspended Sediment

During 2002, water samples were collected by lowering an acid-cleaned Tygon® tube 

attached to a Teflon® weight through the ice into the seawater and pumping with a handoperated peristaltic pump. The first two liters of water were discarded and the next two 

liters were pumped directly into a 2-L, LDPE bottle. The sample containers were sealed 

in plastic bags, labeled and placed in coolers for transport back to the onshore laboratory. 

During 2001, samples of water from under the ice were collected using a Wheaton® pole 

that was rigged with a 1-L sample bottle. In the lab, the water samples were brought to 

room temperature, shaken to resuspend the particles and the turbidity of each sample was 

determined using a Hach® Model 2100A turbidimeter. The salinity of each seawater

sample also determined using a Reichert-Jung® Model 10419 optical refractometer.

In the on-site laboratory at the STP, the water samples were vacuum filtered through 

polycarbonate filters (Poretics®, 47-mm diameter, 0.4-μm pore size). Prior to the field 

effort, the filters were acid washed in 5N HNO3, rinsed three times with distilleddeionized water (DDW), dried and then weighed to the nearest μg using a Sartorius®

Model M3P electronic balance under cleanroom conditions. Vacuum filtration on site 

was carried out in a Class-100 laminar-flow hood using acid-washed glassware. The 

particle-bearing filters were sealed in acid-washed petri dishes, labeled and then doublebagged in plastic and stored until dried and re-weighed at Florida Institute of Technology 

(FIT). 

2.3 Sampling during Open-Water Periods

In-situ profiles of seawater turbidity, conductivity, temperature, depth, current speed and 

direction were obtained during 2000, 2001 and 2002 using an Aanderaa® Instruments 

system consisting of a Model 3500 Doppler current sensor, Model 3231 CTD sensor and 

Model 3712 turbidity/temperature sensor. The raw data were received by an Aanderaa®

Model 3660 Datalogger and stored in a Model 2990 data storage unit. The raw data were 

transformed to appropriate units using equations provided with the Aanderaa® 5059

software package. The processed data were stored on hard disk with multiple backups on 

floppy diskettes.
10

Samples of surface seawater for turbidity and total suspended solids (TSS) were collected 

from the bow of a small rubber boat while rowing upstream or upwind. An acid-washed 

1- or 2-L LDPE bottle was opened at about 10 cm below the surface of the water. When 

the bottle was full, it was sealed beneath the surface, retrieved, and placed in a plastic bag 

for storage. Subsurface samples were collected by lowering a Teflon®-lined Niskin®

sampler attached to a Kevlar® hydrowire beneath the sea surface and tripping it with a 

Teflon® messenger for 1999 through 2001. After retrieval, the water samples were

transferred to acid-washed 5-L plastic containers through a Tygon® tube. During 2002, a 

peristaltic pumping system (Masterflex® model 75-45-30 pump with high-capacity pump 

head) was used to collect water samples through acid-cleaned Tygon® tubing attached to 

a Teflon® weight. Approximately 10 L of water were discarded before the sample was 

pumped directly into an acid-washed 5-L plastic container. All water samples were

sealed in plastic bags, labeled, packed in coolers and taken to an on-site laboratory at the 

STP. 

In the lab, the water samples were shaken to resuspend the particles in the water; then, the 

turbidity of each sample was determined using a Hach® Model 2100A turbidimeter that 

was calibrated with sealed standards. The salinity of each seawater sample also was 

determined using a Reichert-Jung® Model 10419 optical refractometer that was calibrated 

with standard seawater. Salinity was determined for selected seawater samples by

inductive salinometer upon return to FIT to validate the data obtained with the Aanderaa®

system and the optical refractometer. In the on-site laboratory, the water samples were 

vacuum filtered through polycarbonate filters as described above for the river water.

2.4 Laboratory Analyses

2.4.1 Particulate Organic Carbon

Samples for particulate organic carbon (POC) were prepared by filtration of seawater and 

river water through pre-combusted Gelman Type A/E glass fiber filters mounted on 

acid-washed filtration glassware within a Class-100 laminar-flow hood. The POC filters 

were sealed in acid-washed Petri dishes, labeled and double bagged in plastic. 

At FIT, the POC filters were treated with H3PO4 to remove inorganic carbon phases, 

rinsed with DDW, dried and their particulate mass determined. The filters were then

placed in ceramic boats and combusted at 900°C in a Shimadzu TOC-5050A carbon 

system with SSM-5000A solid sampling module following the manufacturer’s

instructions. The POC content of the samples was determined using a four-point 

calibration curve with pure sucrose as the standard. The calibration curve was checked 

every 10 samples by analyzing the certified reference material (CRM) MESS-2 and

MESS-3, marine sediment samples issued by the National Research Council of Canada 

(NRC).

2.4.2 Trace and Major Metals in Suspended Sediment

Filters bearing field samples of suspended sediment, as well as separate milligram

quantities of standard reference material (SRM) #2704, a river sediment SRM issued by 
11

the National Institute of Standards and Technology (NIST), were digested in stoppered, 

15-mL Teflon test tubes using Ultrex II HNO3, HF and HCl. The sealed test tubes 

were placed in an 80°C water bath where refluxing of the acids completely dissolved the 

particles on the filters. After processing, the resultant solutions were transferred to acidwashed, 15-mL polyethylene bottles, diluted to ~6 mL with DDW rinses of the Teflon®

test tubes and stored in a plastic bag until analyzed.

Metal concentrations for the digested particulate samples, SRMs and blanks were

determined by FAAS, GFAAS or ICP-MS in a manner compatible with EPA Series

7000, 6010A and 7470 (U.S. EPA, 1991), respectively (Table 2-1). Concentrations of 

particulate Al, Ca, Fe, K, Mg, Mn, Na and Zn were determined by FAAS using a PerkinElmer®

 Model 4000 AAS. Concentrations of Cr and Cu were quantified by GFAAS 

using a Perkin-Elmer® Model 4000 AAS equipped with an HGA-400 graphite furnace

and AS-40 autosampler. Concentrations of As were determined by GFAAS using a 

Perkin-Elmer® model 5100 instrument equipped with an HGA-600 graphite furnace and 

an AS-60 autosampler. Values for Ba, Cd and Pb were determined by ICP-MS using a 

Perkin-Elmer® ELAN 5000 spectrometer. In all cases, the instrument manufacturers’

specifications were followed and adherence to QA/QC requirements was maintained.

2.4.3 Scanning Electron Microscopy

Selected samples were studied by scanning electron microscopy (SEM) at the University

of Miami. The dried particles were spread across double-sided tape on a standard SEM 

stub and coated with Pd. A Philips/FEIESEM-FEG instrument was used for the

investigation. The instrument was equipped with an Oxford/LinkISIS 300 energy

dispersive X-ray spectrometer (EDS). With the EDS, elemental analysis was carried out 

at selected areas on the particles. 
12

Table 2-1. Summary of instrumental methods and method detection limits (MDL) for metal 

analysis of suspended sediment.

Suspended sediment

Metal Method MDLs

(Fg metal/g,

dry weight)

Al – aluminum FAAS 1500

As – arsenic GFAAS 1.8

Ba – barium ICP-MS 9

Ca – calcium FAAS 230

Cd – cadmium ICP-MS 0.03

Cr – chromium FAAS 0.33

Cu – copper FAAS 0.4

Fe – iron FAAS 250

K – potassium FAAS 250

Mg – magnesium FAAS 40

Mn – manganese FAAS 170

Ni – nickel ICP-MS 0.7

Pb – lead ICP-MS 0.2

Na – sodium FAAS 82

Zn – zinc FAAS 2

POC/DOC Shimadzu

Carbon System

0.01%

Notes:

CVAAS = Cold Vapor Atomic Absorption Spectrometry

FAAS = Flame Atomic Absorption Spectrometry 

GFAAS = Graphite Furnace Atomic Absorption Spectrometry

ICP-MS = Inductively Coupled Plasma-Mass Spectrometry 

MDL = Method Detection Limit

2.5 Quality Assurance and Quality Control

2.5.1 Sample Tracking Procedure 

All sediment samples were collected by, transported by and stored by personnel from

FIT. Upon return-to or arrival at the laboratory, each sample was carefully inspected to 

insure that it was intact and that the identification number was clearly readable.

 

2.5.2 Quality Control Measurements for Analysis 

For this project, QC measures included balance calibration, instrument calibration

(FAAS, GFAAS, CVAAS, ICP-MS, TOC analyzer, and in-situ instrument sensors),

matrix spike analysis for each metal, duplicate sample analysis, analysis of CRMs and 

SRMs, procedural blank analysis and standard checks. With each batch of up to 20 

samples, two procedural blanks, two CRMs or SRMs, two duplicate samples and two 
13

matrix-spiked samples were analyzed. Data quality objectives (DQOs) for these quality 

control measurements are provided in Table 2-2. 

2.5.3 Instrument Calibration 

Electronic balances used for weighing samples and reagents were calibrated prior to each 

use with certified, NIST-traceable standard weights. All pipets (electronic or manual) 

were calibrated prior to use. Each of the spectrometers used for metal analysis was 

initially standardized with a three- to five-point calibration with a linear correlation

coefficient of r ≥ 0.999 required before experimental samples could be analyzed. 

Analysis of complete three- to five-point calibrations and/or single standard checks

alternated every 5-10 samples until all the analyses were complete. The relative standard 

deviation (RSD) between complete calibration and standard check was required to be

<15% or recalibration and reanalysis of the affected samples were performed.

2.5.4 Matrix Spike Analysis 

Matrix spikes were prepared for a minimum of 5% of the total number of samples

analyzed and included each metal to be determined. Results from matrix spike analysis 

using the method of standard additions provides information on the extent of any signal 

suppression or enhancement due to the sample matrix. If necessary (i.e., spike results 

outside 80-120% limit), spiking frequency was increased to 20% and a correction applied 

to the metal concentrations of the experimental samples. 

2.5.5 Duplicate Sample Analysis 

Duplicate samples from homogenized field samples (as distinct from field replicates)

were prepared in the laboratory for a minimum of 5% of the total samples. These

laboratory duplicates were included as part of each set of sample digestions and analyses 

and provide a measure of analytical precision.

2.5.6 Procedural Blank Analysis 

Two procedural blanks were prepared with each set of 20 samples to monitor potential 

contamination resulting from laboratory reagents, glassware and processing procedures. 

These blanks were processed using the same analytical scheme, reagents and handling 

techniques as used for the experimental samples.
14

Table 2-2. Data quality objectives and criteria.

Element or Sample Type 

Criteria

Minimum Frequency Data Quality

Objective/Acceptance

Initial Calibration Prior to every batch of samples

Standard Curve

3-5 point curve depending

on the element and a blank

Correlation coefficient r = 

0.999 for all analytes

Continuing Calibration Must end every analytical 

sequence; for flame, repeat 

all standards every 5 samples; 

for graphite furnace and ICPMS recheck standard 

 after every 8-10 samples

% RSD ?15% for all analytes

Certified and Standard

Reference Materials

Two per batch of 20 samples Values must be within 20%

of accepted values for 

>85% of the certified 

analytes and within 25% for 

Hg

Method Blank Two per batch of 20 samples No more than 2 analytes to 

exceed 5x MDL

Matrix Spike and

Spike Method Blank

Two per batch of 20 samples 80-120%

Lab Duplicate Two per batch of 20 samples RSD <25% for 65% of

analytes

2.5.7 CRM and SRM analysis 

A common method used to evaluate the accuracy of environmental data is to analyze 

reference materials, samples for which consensus or "accepted" analyte concentrations 

exist. The following CRMs and SRMs were used: Buffalo River sediment SRM#2704 

(NIST) and Marine Sediment CRM MESS-2 (NRC). Metal concentrations obtained for 

the reference materials were required to be within ?20% of accepted values for >85% of 

other certified analyses. Results for the CRMs and SRMs were well within the limits set 

in the DQOs (Table 2-3). 
15

Table 2-3. Results for reference materials.

a

 ± 95 confidence limits.

b

 ± 1 standard deviation.

c

 MESS-2 (NRC).

Results for QA/QC measurements for each data set are given with along the complete 

data sets in Appendices A, B and C.

Analyte

Certified

Concentrations for SRM #2704

a

(μg/g)

This studyb

(μg/g)

Al (n = 38) 6.11 ± 0.16 (%) 6.14 ± 0.08 (%) 

As (n = 38) 23.4 ± 0.8 23.4 ± 0.8

Ba (n = 38) 414 ± 12 418 ± 7

Ca (n = 8) 2.60 ± 0.03 (%) 2.59 ± 0.03 (%)

Cd (n = 30) 3.45 ± 0.22 3.44 ± 0.11

Cr (n = 30) 135 ± 5 134 ± 3

Cu (n = 40) 98.6 ± 5.0 99.7 ± 2.8

Fe (n = 40) 4.11 ± 0.1 (%) 4.13 ± 0.05 (%)

K (n = 8) 2.00 ± 0.04 (%) 2.00 ± 0.03 (%)

Mg (n = 10) 1.20 ± 0.02 (%) 1.19 ± 0.03 (%)

Mn (n = 10) 555 ± 19 566 ± 12

Na (n = 10) 0.547 ± 0.014 (%) 0.55 ± 0.03 (%)

Ni (n = 8) 44.1 ± 3.0 45.7 ± 3.8

Pb (n = 38) 161 ± 17 159 ± 9

Zn (n = 42) 438 ± 12 436 ± 8

POC (n = 25) 2.14 ± 0.03 (%)c2.00 ± 0.05 (%)
16

3.0 RESULTS AND DISCUSSION

The Results and Discussion are organized so that they begin with the input of suspended 

sediment by rivers and then transition to the transport and distribution of suspended 

sediment in the coastal Beaufort Sea. Specifically, sediment transport by the

Sagavanirktok, Kuparuk and Colville rivers will be presented for 2001 and 2002. Then, 

the composition of the river particles will be introduced and contrasted with bottom 

sediments in the coastal Beaufort Sea. The transport and composition data are used to

calculate riverine inputs of suspended sediment as well as particulate metals and

particulate organic carbon to the Beaufort Sea. Next, the spring flow of suspended

sediment over and under the 2-m thick ice in the Beaufort Sea is introduced along with 

data for suspended sediment in ice cores. Subsequently, the distribution and composition 

of suspended sediment in the Coastal Beaufort Sea during the open-water period is

presented. Finally, a brief overview of sediment accumulation is provided.

3.1 River Sources of Suspended Sediment

Most rivers that drain into the Arctic Ocean carry 40 to 80% of their annual volume of 

water during peak flow in May, June and July (Arnborg et al., 1967; Gordeev et al,

1996). Studies in the Alaskan Arctic have shown that concentrations of total suspended 

solids (TSS) in the Colville River follow the same trend as water flow with >70% of the 

annual discharge of TSS occurring during May and June (Arnborg et al., 1967). Large 

seasonal discharges of water and suspended sediment at high latitudes emphasize the 

importance of annual spring floods to the arctic hydrologic cycle. 

The three rivers studied during the ANIMIDA program, the Sagavanirktok, Kuparuk and 

Colville rivers (Figure 3-1), lie within the Arctic climatic zone where annual

temperatures average -12°C and mean precipitation is ~12 cm y-1 (Telang et al., 1991). 

The drainage basins of these Arctic rivers include the following three physiographic

provinces: the Arctic Mountain Province, the Arctic Foothills Province, and the Arctic 

Coastal Plain Province (Payne et al., 1951). Based on the classification scheme proposed 

by Craig and McCart (1975), the Sagavanirktok and Colville rivers can be classified as 

mountain streams that drain snowfields and glaciers in the Brooks Range. In contrast, the 

yellow-colored water of the Kuparuk River is more representative of a tundra stream

(Lock et al., 1989). All three rivers flow into the coastal Beaufort Sea.

Rivers are an important source of water and sediment to the ANIMIDA study area during 

spring runoff and on an annual basis. The river-borne water and sediment carry a full, 

natural complement of dissolved and particulate elements that are physically and

chemically weathered from the mountains and tundra bordering the coastal Beaufort Sea. 

To understand possible anthropogenic perturbations to the ANIMIDA study area, one 

must first understand the composition, flow characteristics and amounts of incoming

sediment and water. In this regard, the Sagavanirktok, Kuparuk and Colville rivers 

(Figure 3-1 and Table 3-1) were sampled during spring runoff (May-June) in 2001 and 

2002 and during the summers (July-August) of 2000, 2001 and 2002. During breakup, 

the Sagavanirktok River was sampled daily and the other two rivers were sampled every 

two to five days as logistics permitted. 
17

Figure 3-1. Map showing locations of sampling sites in the Sagavanirktok, Kuparuk and Colville 

rivers with inset map showing study area in northern Alaska.

Table 3-1. Locations of river sampling sites.

Site Latitude (N) Longitude (W)

Sagavanirktok River

(near Prudhoe Bay) 70° 15.033? 148° 18.484?

Sagavanirktok River

(~30 km upstream at mile 401 on 

the Dalton Highway)

70° 01.684? 148° 37.781?

Sagavanirktok River

(U.S.G.S. gauge at mile 327 on the 

Dalton Highway )

69° 00.527? 148° 49.214?

Kuparuk River 70° 19.812? 149° 00.527?

Colville River 70° 09.519? 150° 56.791?

U.S.G.S.

Gauge

Mile 401
18

3.1.1 River Breakup and Summer: 2001 

3.1.1.1 Sagavanirktok River 

Water began to flow in the Sagavanirktok River on June 3, 2001 (Figure 3-2). Samples 

were collected daily from June 3 to June 23 and later on July 30 and August 8 from the 

bridge near the Prudhoe Bay Operations Center (PBOC). Samples also were collected at 

mile 401 on the Dalton Highway on June 5, 11, 12, 16, 19 and 21 and at the site of a 

gauging station (mile 327 on the Dalton Highway) maintained by the U.S. Geological 

Survey (U.S.G.S.) on June 14 and 21, about 150 km south of Deadhorse.

 

 

 

 

Figure 3-2. Sagavanirktok River on May 25, June 3, June 5, and June 11, 2001 at bridge near 

Prudhoe Bay Operations Center.

Concentrations of total suspended solids (TSS) in the Sagavanirktok River at PBOC

increased from ~40 mg/L on June 3 to 600 mg/L within 10 days on June 12 and then 

decreased to ~30 mg/L by June 18 (Figure 3-3). A secondary pulse occurred about June 

23 when concentrations of TSS rose to ~90 mg/L following a rain storm (Figure 3-3). 

Data for water flow at the U.S.G.S. gauge, located ~150 km upstream, followed a similar 

trend. A 1- to 2-day offset between the peaks in TSS and water flow is due to the 150 km 

difference in location between the gauge and primary sampling site (Figure 3-1). 

Concentrations of TSS in the Sagavanirktok River at mile 401 on the Dalton Highway

and the U.S.G.S. gauge site (mile 327 on the Dalton Highway) were similar to values 

May 25, 2001 June 3, 2001

June 5, 2001 June 11, 2001
19

6/1/01 6/8/01 6/15/01 6/22/01 

Water Discharge (m

3/s)

0

100

200

300

400

Total Suspended Solids (mg/L)

0

100

200

300

400

500

600

700

TSS 

Water Flow Calculated

Water Flow Measured

Sagavanirktok River 2001

Figure 3-3. Water discharge (near mile 327 on Dalton Highway, U.S. Geological Survey, 2001) 

and concentrations of total suspended solids (TSS) in the Sagavanirktok River at 

PBOC during June 2001.

obtained from the PBOC bridge, considering a lag time of several hours (mile 401) to 2 

days (mile 327). However, the gauge in the Sagavanirktok River was not installed by the 

U.S.G.S. until the river was free of ice on June 10, 2001, ~7 days after water flow began. 

Thus, during 2001 and most other years, the ascending limb of the hydrograph is

calculated, not measured, for the Sagavanirktok River. Furthermore, because the gauge is 

upstream in the western drainage basin of the Sagavanirktok River, the gauge records 

water flow for only ~20% of the watershed and may not characterize flow patterns for the 

entire basin. During 2001, the total volume of water measured at the U.S.G.S. gauge in 

the Sagavanirktok River was ~1.3 km3, yielding a total extrapolated (from 20% to 100%) 

flow of ~6.5 km3 y

-1 (U.S.G.S., 2001). 

The conductivity of the water in the Sagavanirktok River during June 2001 (Figure 3-4) 

was inversely related to water flow (Figure 3-3) because at peak flow the concentrations 

of dissolved solids are diluted with large amounts of snowmelt that has had limited

contact with soils and surface waters. The conductivity of melted snow was 7 μS. 

Between June 3, 2001, and June 7, 2001, the conductivity of the Sagavanirktok River 

decreased by almost 50% (Figure 3-4). Extensive discussion of dissolved components in 

the Sagavanirktok River during June 2001 is given in Trefry et al. (2004). 

During late July and August 2001, concentrations of TSS were ~2 mg/L and the

conductivity was ~320μS. 
20

June

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Conductivity (

μS)

0

50

100

150

200

250

300

Sag PBOC 

Sag USGS Gauge 

Sag Dalton Hwy Mile 401

Sagavanirktok River 2001

Figure 3-4. Conductivity for water from the Sagavanirktok (Sag) River for June 2001 near

Prudhoe Bay Operations Center (PBOC), US Geological Survey gauge, and at mile 

401 on the Dalton Highway.

3.1.1.2 Kuparuk River 

In the Kuparuk River, concentrations of TSS reached peak values of 60 mg/L on June 10, 

2001, and decreased to <5 mg/L after June 16 (Figures 3-5 and 3-6). Peak flow recorded 

for the Kuparuk River was about 600 m3/sec on June 12, 2001, decreasing to <50 m3/sec 

after June 28, 2001. Values for TSS were ~0.6 mg/L during August 2001 for the

Kuparuk River.

 

Figure 3-5. Kuparuk River causeway/bridge (eastern segment of river) shown under water during 

peak flow on June 11, 2001 and then high and dry and rebuilt on June 20, 2001. 

June 11, 2001 June 20, 2001
21

 

6/1/2001 6/8/2001 6/15/2001 6/22/2001

Water Discharge (m

3/s)

0

500

1000

1500

2000

Total Suspended Solids (mg/L)

0

25

50

75

100

TSS

Calculated Water Flow

Measured Water Flow

Kuparuk River 2001

Figure 3-6. Concentrations of total suspended solids (TSS) and water discharge for the Kuparuk 

River (flow data from US Geological Survey) for June 2001.

June

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Conductivity (

μS)

0

50

100

150

200

250

300

Sag PBOC 

Kup2 

Kup1 

Figure 3-7. Conductivity for water from the Kuparuk (Kup) and Sagavanirktok (Sag) rivers for 

June 2001. 

Water conductivity in the Kuparuk River during June 2001 was indirectly related to water 

flow with lowest values for conductivity during highest flow as the concentrations of 

dissolved substances were diluted by the increased volumes of fresh snowmelt (Figure 3-

7). Samples from the eastern stem of the Kuparuk River were collected at two different 

locations (separated by <1 km) during peak flow due to problems with accessibility 

during the flood period. However, subsequent sampling on the same days at both sites 

showed no significant differences in TSS or conductivity (e.g., Figure 3-7 for Kup1 and 

Kup2). Conductivities for the Kuparuk River were two to three times lower than found 

for the Sagavanirktok River due to the greater amount of limestone weathered and

dissolved in the Sagavanirktok River as discussed in Trefry et al. (2004). During August, 

the conductivity for the Kuparuk River was about 50% higher at ~160 μS. 
22

3.1.1.3 Colville River 

Concentrations of TSS in the Colville River followed similar trends to those observed for 

the Sagavanirktok River with maximum levels of about 600 mg/L on June 13, 2001

(Figures 3-8 and 3-9). Values for TSS were about 6 mg/L during August 2001 for the 

Colville River. Flow data for the Colville River were collected only during the period of 

peak flow by Baker et al. (2001); the U.S.G.S. does not maintain a gauge on the Colville 

River. During the spring snow melt, flow in the Colville River (6,000 to 9,000 m3/sec) 

was an order-of-magnitude greater than in the Sagavanirktok or Kuparuk rivers. As 

observed for the other rivers, conductivity decreased during peak flow (Figure 3-10). 

The conductivity of water in the Colville River was similar to that found for the Kuparuk 

River, with both rivers more two-fold lower in conductivity that the carbonate-rich waters 

of the Sagavanirktok River.

 

Figure 3-8. Colville River at Monument 1 during peak flow on June 9, 2001 and at lower flow on 

June 20, 2001. 

June 2001

8 10 12 14

Water Discharge (m

3/s)

2000

4000

6000

8000

10000

Channel Ice

 Intact

Channel Ice

 Clear

Colville River 2001

 

Colville River 2001

June 2001

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

TSS (mg/L)

0

100

200

300

400

500

600

Figure 3-9. Water flow and concentrations of total suspended solids (TSS) for the Colville River 

during June 2001. Water data during peak flow are from Baker et al. (2001); the 

U.S.G.S. does not maintain a water flow gauge on the Colville River. 

June 9, 2001 June 20, 2001
23

June

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Conductivity (

μS)

0

50

100

150

200

250

300

Sag PBOC 

Col 

Figure 3-10. Conductivity for water from the Colville (Col) River and the Sagavanirktok (Sag) 

River at the Prudhoe Bay Operations Center (PBOC) for June 2001.

In addition to TSS, conductivity and water flow, concentrations of particulate and

dissolved trace metals (As, Ba, Cu, Fe, Mn, Ni, Pb and Zn), particulate Al, K, Mg and 

Na, and DOC and POC were determined for the three rivers during June to August 2001. 

Particle composition is presented in this report following the TSS, conductivity and water 

flow results for 2002 and the dissolved data are presented in Trefry et al. (2004). 

3.1.2 River Breakup and Summer: 2002

3.1.2.1 Sagavanirktok River 

Spring breakup in the Sagavanirktok River for 2002 was very different from what was 

observed in 2001. First, the start of river flow was almost two weeks earlier (May 20, 

2002 versus June 2, 2001). Second, after flow had been ongoing for about one week, the 

air temperatures cooled well below freezing and the river refroze (Figure 3-11). The 

same trend was observed offshore as river water initially flowed out over and under the 

ice and then the surface layer of river water froze over the 2-m thick layer of winter ice. 

The river re-thawed within four days, but water flow was less than during the earlier 

discharge period (Figure 3-12).

 

The TSS and turbidity for 2002 showed the same initial steep increase in levels of

suspended particles to ~350 mg/L (Figure 3-12), similar to, but lower than the observed 

peak TSS of ~600 mg/L in 2001 (Figure 3-3, page 19). However, subsequent cold

temperatures and freezing of the river truncated the flooding process and TSS levels

decreased to <10 mg/L on May 31, 2002, the final day of operations before the ice 

prevented sampling for two days. Then, as the river re-melted, the increase in flow led to 

another peak in discharge of suspended sediment at >200 mg/L (Figure 3-12). Data for 

turbidity also are shown on Figure 3-12 to point out that turbidity data sets are available 
24

 

Figure 3-11. Sagavanirktok River flowing on May 22, frozen on May 29, and flowing again on 

May 31 and June 12, 2002 at bridge near Prudhoe Bay Operations Center.

for all water samples (Appendix A) and that the two indicators of suspended sediment 

content track one another very well. 

Unfortunately, the U.S.G.S. was not able to install their gauge for water flow until June 6, 

2002 (Figure 3-12), and therefore no data are available for the events described above. 

Even without flow data for late May and early June, 2002, the plots for concentrations of 

TSS for 2001 versus 2002 support much lower net transport of sediment during 2002. 

Some of the sediment carried by the river in 2002 may have settled upstream and then 

washed out to the Beaufort Sea during a later storm in 2002 or even during the 2003

spring flood. 

Conductivity in the Sagavanirktok River followed a more compressed trend in 2002 with 

a shorter time of 4 days at <200 μS (Figure 3-13) relative to the 8-day period of water 

flow with conductivity <200 μS observed in 2001 (Figure 3-4, page 20). Concentrations 

of TSS decreased to ~3 mg/L in late June and were ~1 mg/L in August, similar to levels

observed in 2001.

 

May 22, 2002 May 29, 2002

May 31, 2002

June 12, 2002
25

05/20/02 05/27/02 06/03/02 06/10/02 06/17/02 

TSS (mg/L) and Turbidity (NTU)

0

50

100

150

200

250

300

350

400

Turbidity (NTU) 

TSS (mg/L)

Sagavanirktok River 2002

river froze

river re-melted

river flood begins

rain 

Figure 3-12. (a) Concentrations of total suspended solids (TSS) and turbidity for the

Sagavanirktok River during May-June 2002. (b) Water discharge (from U.S.

Geological Survey) in Sagavanirktok River for June 2002. 

05/27/02 06/03/02 06/10/02 06/17/02 06/24/02 

Water Discharge (m3/s)

0

100

200

300

400

500

USGS Gauge Installed 6/6/2002

Sagavanirktok River 2002

(a)

(b)
26

05/20/02 05/27/02 06/03/02 06/10/02 06/17/02 

Conductivity (μS)

0

50

100

150

200

250

300

Sagavanirktok

Kuparuk 

Colville

Figure 3-13. Conductivity in the Sagavanirktok, Kuparuk and Colville rivers during

May-June 2002.

3.1.2.2 Kuparuk River 

During 2002, we were fortunate to directly observe and sample the Kuparuk River during 

its brief (1 to 2 day) flood (Figures 3-14 and 3-15). The strong pulse of water that

characterizes flooding in the Kuparuk River occurred on May 23, 2002. The pictures in 

Figure 3-14 show the swelling river on May 22, overflow of the eastern bridge on May 

23, a broad floodplain on May 24 and the receded water after the flood on May 25. The 

complete flood cycle in the Kuparuk River occurred before the onset of colder

temperatures and refreezing of the rivers.

 

Figure 3-14. Kuparuk River during flood period in May 2002.

May 22, 2002 May 23, 2002

May 24, 2002 May 25, 2002
27

05/27/02 06/03/02 06/10/02 06/17/02 06/24/02 

Water Discharge (m

3/s)

0

100

200

300

400

500

600

USGS Gauge Installed 5/27/2002

Kuparuk River 2002

 

5/20/02 5/27/02 6/3/02 6/10/02 6/17/02 6/24/02 

TSS (mg/L)

0

20

40

60

80

100

120

140

160

Kuparuk River 2002

Figure 3-15. Water flow and concentrations of total suspended solids (TSS) and turbidity for the 

Kuparuk River during May-June 2002 (flow data from U.S. Geological Survey). 

Maximum levels of TSS in the Kuparuk River during 2002 were similar to maximum 

levels of ~60 mg/L during 2001. Turbidity and concentrations of TSS in the Kuparuk

River during both years may have peaked at higher levels than observed during

maximum flood stage (Figure 3-15). Unfortunately, due to washing out of the road and 

the intense flow conditions, sampling was restricted to the eastern-most braid of the river 

during peak flow. Concentrations of TSS in the Kuparuk River decreased to ~0.5 mg/L 

in late June and were ~0.2 mg/L in August, similar to levels observed in 2001. 

Conductivity in the Kuparuk River during 2002 (Figure 3-13) followed a similar trend at 

similar values to those observed in 2001 (Figure 3-7) with a minimum of ~50 μS at peak 

flow, increasing to ~120 μS after the spring flood receded. 

3.1.2.3 Colville River 

Access to the Colville River by helicopter was limited during 2002 due to the early onset 

of the spring floods and an increased focus on the under-ice effort near Prudhoe Bay. 

Data from Baker et al. (2002) show a short, strong pulse of water at >6000 m3/sec for 4-5 

days (Figure 3-16). Duplicate samples for TSS on May 27, 2002, showed levels >600 

mg/L. Levels of TSS decreased to 112 mg/L on June 3 and <50 mg/L on and after June 

12 (Figure 3-17). Conductivity for the Colville River during the 2002 flood (Figure 3-13) 

event was very similar to that observed during 2001 (Figure 3-10). During both years, 

the Colville River had the lowest conductivity of the three rivers, most likely due in part 

to the higher water flow of the river that led to dilution of dissolved solids. 

May 2002

24 26 28 30

Water Discharge (m

3/s)

2000

4000

6000

8000

10000

Channel Ice

 Clear

 

5/20/02 5/27/02 6/3/02 6/10/02 6/17/02 

TSS (mg/L)

0

100

200

300

400

500

600

700

Figure 3-16. Water flow and concentrations of total suspended solids (TSS) in the Colville River 

during May-June 2002. 
28

 

Figure 3-17. Colville River after the spring flood during June 2002.

3.2 Composition of River Suspended Sediment

The composition of river suspended matter can provide a well-defined signature that may 

allow differentiation between incoming natural suspended sediment and anthropogenic 

contributions of various solids from industrial activity in the coastal Beaufort Sea.

Furthermore, changes in the composition of the river-borne particles may help identify 

future shifts in mechanical and chemical weathering in the Brooks Range and across the 

North Slope. Results for both 2001 and 2002 are discussed in this section. 

Figure 3-18 shows a scanning electron micrograph of a subset of the particles carried by 

the Sagavanirktok River on June 9, 2001. The small holes in the background are the 0.4 

μm pores in the membrane filter. Thus, on June 9 as flow increased, platy, clay-sizeparticles in the range of 1-5 μm are intermixed with larger fragments on the order of 5-10 

μm. The particles from the Sagavanirktok and Colville Rivers (Figure 3-18 and 3-19) 

include an abundance of K-rich aluminosilicates as described below. 

Summary data for major elements (Al, Fe, Ca, K, Mg and Na), trace metals (As, Ba, Cd, 

Cu, Mn, Ni, Pb and Zn) and POC for suspended sediment collected from the three rivers 

during 2001 and 2002 are presented in Tables 3-2 and 3-3. Distinct differences in the Al 

content of the suspended sediment were observed with Colville>Sagavanirktok>Kuparuk 

(Tables 3-2 and 3-3). In contrast, concentrations of Ca are about 7 to 10 times greater in 

the Sagavanirktok River than in the Kuparuk or Colville rivers. The distinction is very 

clear in the Al versus Ca plot shown in Figure 3-20. These differences are directly

related to the greater abundance of aluminosilicates in the Colville River relative to the 

Sagavanirktok and Kuparuk Rivers as well as a much greater abundance of particulate 

calcite and dolomite in the Sagavanirktok River. During 2002, a clear, indirect

relationship was observed between particulate Ca and particulate Al in the Sagavanirktok 

River (Figure 3-20) due to the greater amounts of coarser-grained carbonate particles 

during high flow and the greater clay content during low flow. Unfortunately, the

distinction in the Ca/Al ratios among the rivers is not easily observed in coastal sediment 

due to the addition of marine shell material to the coastal sediment. 

June 3, 2002 June 12, 2002
29

Sagavanirktok River @ PBOC 6/9/01

Figure 3-18. Scanning electron micrograph showing suspended sediment collected from the 

Sagavanirktok River on June 9, 2001. Red mark on inset hydrograph shows that 

sample was collected as levels of suspended sediment and water flow were 

increasing. 

 

Colville River 6/14/01

Figure 3-19. Scanning electron micrograph showing suspended sediment collected from the 

Colville River on June 14, 2001, during peak flow. 

June 2001

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

TSS (mg/L)

0

100

200

300

400

500

600

Water Discharge (m

3

s-1

)

150

200

250

300

350

400

450

500

Total Suspended Solids

Water Discharge

Sagavanirktok River @ PBOC
30

Table 3-2. Concentrations of metals and organic carbon in suspended sediment from the Sagavanirktok, Kuparuk and Colville rivers during June 

2001.

Sample

Identification

Al

(%)

As

(μg/g)

Ba

(μg/g)

Ca

(%)

Cu

(μg/g)

Fe

(%)

K

(%)

Mg

(%)

Mn

(μg/g)

Na

(%)

Ni 

(μg/g)

Pb

(μg/g)

Zn

(μg/g)

POC

(%)

Sagavanirktok R.

at PBOC

(n=22)

Mean

± SD

5.6

± 0.9

11.1

±1.6

702

±112

6.7

±1.0

32.6

±2.8

3.3

±0.4

1.7

±0.2

0.8

±0.1

583

±27

0.3

±0.1

60.9

±5.1

18.0

±2.0

123

±7

1.6

± 0.5

Sagavanirktok R.

(mile 401 Dalton 

Highway)

(n=6)

Mean

± SD

5.9

± 0.6

13.1

±3.5

663

±118

7.4

±2.0

32.2

±2.7

3.4

±0.3

1.6

±0.2

0.9

±0.1

602

±43

0.3

±0.1

59.0

±7.8

16.7

±1.5

124

±11

1.5

± 0.4

Sagavanirktok R.

(mile 327 Dalton 

Highway) 

(n=2)

Mean

± SD

7.0

± 1.0

15.8

±1.3

729

±52

5.0

±3.6

39.8

±9.4

4.3

±1.0

2.0

±0.3

0.8

±0.1

799

±140

0.3

±0.1

75.0

±8.5

25.8

±7.1

130

±8

-

-

Kupuruk R.

(n=9)

Mean

± SD

4.4

± 1.0

16.6

±8.1

562

±98

1.0

±0.2

31.4

±4.6

3.7

±0.3

1.1

±0.2

0.5

±0.2

836

±144

0.4

±0.1

643.8

±7.6

15.1

±5.1

110

±23

4.8

± 1.5

Colville R.

(n=5)

Mean

± SD

8.3

± 0.3

14.2

±1.3

989

±125

0.7

±0.1

40.8

±2.3

5.0

±0.3

1.9

±0.3

1.1

±0.2

957

±55

0.5

±0.1

68.7

±10.0

24.0

±6.8

130

±11

2.2

± 0.6
31

Table 3-3. Concentrations of metals and organic carbon in suspended sediment from the Sagavanirktok and Kuparuk rivers during June 2002.

Sample

Identification

Al

(%)

As

(μg/g)

Ba

(μg/g)

Ca

(%)

Cu

(μg/g)

Fe

(%)

K

(%)

Mg

(%)

Mn

(μg/g)

Na

(%)

Ni 

(μg/g)

Pb

(μg/g)

Zn

(μg/g)

POC

(%)

Sagavanirktok R.

at PBOC

(n=23)

Mean

± SD

6.2

± 1.1

14.3

± 4.3

693

± 153

8.9

± 1.7

33.5

± 5.8

3.4

± 0.5

1.7

± 0.3

1.1

± 0.1

586

± 68

0.3

± 0.01

52.1

± 6.4

11.7

± 4.2

143

± 31

1.6

± 0.3

Kuparuk R.

(n=13)

Mean

± SD

4.0

± 1.47

14.6

± 3.7

537

± 237

0.9

± 0.2

28.4

± 6.0

4.5

± 0.8

1.1

± 0.3

0.6

± 0.2

1120

± 287

0.2

± 0.2

48.8

± 11.3

18.9

± 3.8

152

± 61

5.3

± 3.1
32

Al (%)

0 2 4 6 8 10

Ca (%)

0

5

10

15

Kuparuk Colville

Sagavanirktok

2001

 

Al (%)

0 2 4 6 8 10

Ca (%)

0

5

10

15

Kuparuk

Sagavanirktok

2002

High Flow

Low Flow

Figure 3-20. Concentrations of aluminum (Al) versus calcium (Ca) for suspended sediment from 

the Sagavanirktok (circles), Colville (squares) and Kuparuk (triangles) rivers

during June 2001 and May-June 2002.

Previous studies have shown that the Sagavanirktok River drains primarily limestone

deposits and has concentrations of dissolved Ca that are ~2 times higher than in the

Kuparuk and Colville rivers (Telang et al., 1991). In addition to the Lisburne limestone 

and dolomite from the Tertiary, the Brooks Range also contains shales from the Triassic 

to Pennsylvanian age (Payne et al., 1951; Mull and Adams, 1989). The Gubik formation 

(Quaternary riverine and marine sediments) underlies the coastal plain and Quaternary 

sediments, older Cretaceous and Tertiary sandstones, conglomerates and siltstones are 

exposed in the foothills province (Payne et al., 1951; Mull and Adams, 1989). 

As previously noted, the Sagavanirktok and Colville rivers can be classified as mountain 

streams that drain snowfields and glaciers in the Brooks Range according to the

classification scheme proposed by Craig and McCart (1975). In contrast, the yellowcolored water of the Kuparuk River is more representative of a tundra stream (Lock et al., 

1989). All three rivers flow into the coastal Beaufort Sea. These distinctions in source 

among the rivers help explain differences in both particulate and dissolved components 

among the rivers. 

Differences in the K and Mg concentrations of river suspended sediment also were

observed among the rivers with an overall trend of Colville>Sagavanirktok>Kuparuk

(Tables 3-2 and 3-3, Figure 3-21). However, these differences were much less distinct 

than those previously shown for Ca (Figure 3-20). In fact, the K/Al and Mg/Al plots 

show good linear relationships for the combined data set for all three rivers (Figure 3-21). 

These trends suggest that the source minerals bearing K and Mg are similar for each river 

and that the linear variations are due to differences in the fractional amount of the K and 

Mg phases in the suspended sediment. Within the overall linear trend for the combined 

data set, concentrations of particulate K and Mg, relative to Al, are lower in the Kuparuk 

and Colville Rivers than for the Sagavanirktok River (Figure 3-21). This distinction 

among rivers is partially explained by the work of Walker and Webber (1979) that

showed that westward of the carbonate-rich Sagavanirktok River, soil pH decreases from 
33

Al (%)

2 4 6 8 10

K (%)

0

1

2

3

4

Sagavanirktok 2001

Sagavanirktok 2002

Kuparuk 2001 

Kuparuk 2002

Colville 2001 

Y = 0.23 X + 0.25

 r = 0.88

Al (%)

2 4 6 8 10

Mg (%)

0.0

0.5

1.0

1.5

Sagavanirktok 2001

Sagavanirktok 2002

Kuparuk 2001

Kuparuk 2002 

Colville 2001 

Y = 0.12 X + 0.16

 r = 0.78

Figure 3-21. Concentrations of aluminum (Al) versus potassium (K) and magnesium (Mg) for 

suspended sediment from the Sagavanirktok (circles), Colville (squares) and

Kuparuk (triangles) rivers during June 2001 and May-June 2002.

>7 to <6 as the tundra shifts from wet alkaline to wet acidic because soils become rich in 

organic acids. Other studies have shown that soil pH can decrease to 4.2 in tussock 

tundra and heath ecosystems (Valentine and Binkley, 1992). In addition, Parkinson 

(1977) found an inverse relationship between calcium carbonate equivalents and organic 

matter concentrations in the region. These data suggest that soils within the Kuparuk and 

Colville drainage basins may undergo more intense chemical weathering due to higher 

concentrations of organic acids and lower pH. By this scenario, Ca, K and Mg would be 

leached from the parent minerals to a greater extent in the Colville and Kuparuk river 

drainage basins. 
34

Rember (2002) reconstructed the composition and amounts of the minerals that were

chemically weathered to yield the dissolved major ions in the Sagavanirktok, Kuparuk 

and Colville rivers. The complete section from Rember (2002) is discussed in Trefry et 

al. (2004), including the details of the calculations. The dominant rock type that is

chemically weathered in each of the three rivers is carbonate (limestone and dolostone) 

that accounts for >80% of the dissolved solids. However, the mass of rock weathered per 

liter of river water is much greater in the Sagavanirktok River than in the Kuparuk and 

Colville rivers as previously suggested by the conductivity data and discussed below. 

During peak discharge in the Sagavanirktok River, a total of ~96 mg/L of rock were

chemically weathered, with 58% carbonates, ~34% evaporates (S- and Cl-bearing 

minerals), and 8% silicates (Figure 3-22). During off-peak discharge in the

Sagavanirktok River, the amount of rock weathered increased to 136 mg/L (Figure 3-22). 

This seasonal trend is consistent with the processes that occur during spring floods in 

northern Alaska. During peak discharge, runoff is confined to the O-horizon of the soil 

and snowmelt is proceeding at a rapid rate. Therefore, the lack of an active soil layer,

combined with a relatively short residence time (contact time) of the snowmelt in the 

drainage basin, does not allow minerals to undergo extensive chemical weathering. 

However, during off-peak discharge, the volume of snow melting decreases and therefore 

the residence time of snowmelt in the mountains and coastal plain increases, thereby 

allowing for increased chemical weathering of the rocks in the drainage basin.

In the Kuparuk River drainage basin on the coastal plain, lower amounts of ~28 and 46 

mg/L of rock (mostly carbonate with some silicate), respectively, were weathered during 

peak and off-peak discharge. These values are significantly lower (~2-3 fold) than the 

amount of rock weathered in the Sagavanirktok River. This trend shows that the

chemical weathering of rocks from the Brooks Range (and additional sources of SO4

2-

) 

relative to chemical weathering on the coastal plain has a large impact on the chemical 

composition of river water. 

The weathering of carbonates and evaporites in the Colville River accounts for 76% of 

the 36 mg/L of rocks weathered during peak discharge and 80% of the 60 mg/L of rocks 

weathered during off-peak discharge. However, the amount of rock weathered is more 

similar to the Kuparuk than the Sagavanirktok River. As previously discussed, the

evaporite and carbonate minerals are primarily located in the drainage basin of the

Sagavanirktok River and are more rapidly weathered than silicate minerals, especially in 

a low precipitation, cold environment. Therefore, the amounts of evaporite and carbonate 

rock weathered in the drainage basin of the Colville River are likely proportional to the 

amounts of evaporite and carbonate rock weathered in the drainage basins of the Kuparuk 

and Sagavanirktok rivers. 
35

Sagavanirktok River Peak Discharge

Total = 96 mg rock chemically weathered/L

Total = 136 mg rock chemically weathered/L

Sagavanirktok River Off-Peak Discharge

Evaporite

Carbonate

Na-Silicate

K-Silicate

Evaporite

Carbonate

Na-Silicate

K-Silicate

Figure 3-22. Fraction of different rock types that were chemically weathered to produce the 

observed concentrations of dissolved major elements in the Sagavanirktok River 

during peak and off-peak flow in 2001.

Concentrations of trace metals in river suspended matter provide another possible point 

of reference for differentiating among river sources of sediment and for comparison with 

bottom sediment in the ANIMIDA study area. Such comparisons enable us to determine 

whether incoming suspended particles have been modified by chemical processes in

marine sediments or if metal concentrations have been enhanced by anthropogenic inputs. 

Results for the Sagavanirktok River from June 2001 show that concentrations of

particulate Cu, Pb and Zn (as μg g-1 dry weight) as well as Fe (as % dry weight) are quite 

uniform with values for the coefficient variance (CV) = 8.5% for Cu, 11% for Pb, 16% 

for Fe, and 5.7% for Zn (Figure 3-23). Concentrations of these metals are poorly
36

correlated with concentrations of organic carbon, and relatively well correlated with

particulate Al (Table 3-4). The poor correlations for POC versus Cu, Fe, Pb and Zn 

suggest that POC does not play a significant role in controlling concentrations of

particulate trace metals in the Sagavanirktok River, but that aluminosilicates (clays) are 

more important. 

 

Ba (

μg/g)

0

500

1000

1500

 

Cu (

μg/g)

0

20

40

60

 

Fe (%)

0

2

4

6

 

Pb (

μg/g)

0

10

20

30

40

Zn (

μg/g)

0

50

100

150

200

250

6/1/01 6/8/01 6/15/01 6/22/01 

POC (%)

0

1

2

3

4

5

6/1/01 6/8/01 6/15/01 6/22/01

Figure 3-23. Concentrations of copper (Cu), lead (Pb), zinc (Zn), iron (Fe), barium (Ba) and 

particulate organic carbon (POC) for suspended sediment from the Sagavanirktok 

River during June 2001. Solid lines show means and dashed lines show ±1

standard deviation.
37

Table 3-4. Correlation coefficients for particulate trace metals and particulate 

organic carbon (POC) in the Sagavanirktok River during June

2001.

** Correlation is significant at the 0.01 level.

* Correlation is significant at the 0.05 level.

The correlation coefficients for concentrations of particulate Ba and particulate Al in the 

Sagavanirktok River follow closely with those observed for Fe, Cu, Pb and Zn,

suggesting that concentrations of particulate Ba also are controlled by the aluminosilicate 

content of the suspended solids (Table 3-4). When concentrations of particulate Ba from 

the Kuparuk and Colville rivers were pooled with data for the Sagavanirktok River 

(Figure 3-24), a strong relationship between Al and Ba is still observed (r = 0.91). The 

data in Figure 3-24 include values from all three rivers with a range of ~2 to >600 mg/L 

for TSS, and concentrations of POC ranging from <1 to >7%. Therefore, variations in 

concentrations of particulate Ba in the Sagavanirktok, Kuparuk and Colville rivers result 

from the dilution of fine-grained aluminosilicates by larger-grained sands and other nonaluminosilicate minerals and not levels of TSS or POC. Results for Ba from the 2002 

samples follow those for 2001 with one exception each from the Sagavanirktok and

Kuparuk rivers that we cannot explain at this time. The trend lines shown on Figure 3-24 

were constructed using sediment data from the ANIMIDA study (Brown et al., 2004) and 

show that Ba levels in suspended sediment from the three rivers generally fit within the 

prediction intervals established for the sediments. Barium is of particular interest to the 

ANIMIDA study because barite (BaSO4) is a common additive to drilling fluids and Ba 

levels in sediments at a few sites in the coastal Beaufort Sea have been previously shown 

to contain anthropogenic Ba contamination (Crecelius et al., 1991; Trefry et al., 2003). 

Average concentrations of particulate Cu, Fe and Pb in the Colville River averaged 25 to 

40% higher than concentrations found in the Sagavanirktok and Kuparuk rivers (Tables 

3-2 and 3-3). However, particles from the Colville River also had 50% higher

concentrations of Al indicating that sources of suspended sediment in the western Brooks 

Range are richer in fine-grained aluminosilicates or less diluted by non-aluminosilicate 

minerals (Tables 3-2 and 3-3). 

When concentrations of particulate Fe were plotted versus Al (Figure 3-25), the results 

for the Sagavanirktok and Colville rivers, and the Kuparuk River during high flow, fit the 

Al Ba Cu Fe Pb Zn

Al 1

Ba 0.88** 1

Cu 0.81** 0.83** 1

Fe 0.97** 0.86** 0.85** 1

Pb 0.82** 0.92** 0.87** 0.83** 1

Zn 0.77** 0.63** 0.51* 0.64** 0.59 1

POC -0.35 -0.18 -0.25 -0.25 -0.28 -0.29
38

Figure 3-24. Concentrations of aluminum (Al) versus barium (Ba) for suspended sediment from 

the Sagavanirktok (circles), Colville (squares) and Kuparuk (triangles) rivers 

during June 2001 and May-June 2002. Solid line is from a linear regression for 

sediment data from the ANIMIDA study area and dashed lines show 99% 

prediction interval for sediment data.

Al (%)

0 2 4 6 8 10

Fe (%)

0

2

4

6

8

Sagavanirktok 2001

Kuparuk 2001

Colville 2001

Sagavanirktok 2002

Kuparuk 2002 

Trend lines from

sediment data

Low Flow

Figure 3-25. Concentrations of aluminum (Al) versus iron (Fe) for suspended sediment from the 

Sagavanirktok (circles), Colville (squares) and Kuparuk (triangles) rivers during 

June 2001 and May-June 2002. Solid line is from a linear regression for sediment 

data from the ANIMIDA study area and dashed lines show 99% prediction interval 

for sediment data.

Al (%)

0 2 4 6 8 10

Ba (

μg/g)

0

500

1000

1500 Sagavanirktok 2001

Kuparuk 2001

Colville 2001

Sagavanirktok 2002 

Kuparuk 2002 

Trend lines from 

sediment data
39

same Fe/Al trend; however, the Colville River had higher absolute levels of both Fe and 

Al. When TSS concentrations decrease to an average of 4 mg/L in the Kuparuk River 

during off-peak discharge in June, the average Fe/Al ratio increased by ~35% relative to 

the Sagavanirktok River (Figure 3-25). These data suggest that elevated concentrations 

of particulate Fe (3.7% dry weight) relative to Al (3.5% dry weight) during off-peak 

discharge may be influenced by high concentrations of dissolved Fe (~60 μg/L) in the 

Kuparuk River that potentially enhance the formation of Fe hydrous oxides and increase 

levels of particulate Fe (Rember and Trefry, 2004). 

Concentrations of Fe and Al fit relatively well within the prediction interval developed 

for these two metals using bottom sediment from the coastal Beaufort Sea and described 

in detail by Brown et al. (2004). Although samples collected from the Kuparuk River 

during low flow (<50 m3/sec) and low levels of TSS (<3 mg/L) were enriched with Fe 

relative to Al (Figure 3-25), very minute amounts of these particles will be carried into 

the Beaufort Sea. Otherwise, the Fe/Al relationship for the suspended sediment collected 

from the rivers matches that found in bottom sediment from the ANIMIDA study area

(Figure 3-25). 

Good relationships were found for Al versus Pb and As (Figure 3-26) and other metals in 

river-borne particles. The few points that indicate elevated levels of Pb and As relative to 

Al in Figure 3-26 coincide with the more Fe-rich particles carried during low flow and at 

low levels of TSS. Otherwise, most data for suspended sediment fit within the prediction 

intervals established from the sediment data (Figure 3-26). Overall, no statistically

significant distinction in metal/Al ratios among rivers has been observed for the metals 

studied, other than the results for the Kuparuk River at low flow (Figure 3-26).

Concentrations of POC for river suspended sediment ranged from <1 to 15 mg/L;

however, the POC, as a percent of the TSS in the Sagavanirktok and Colville rivers were 

quite uniform with an average of ~2% (Tables 3-2 and 3-3, Figure 3-27). In contrast, 

concentrations of POC in the Kuparuk River averaged about 5% (Tables 3-2 and 3-3, 

Figure 3-27). 

 
40

Al (%)

0 2 4 6 8 10

Pb (

μg/g)

0

10

20

30

40 Sagavanirktok 2001 

Kuparuk 2001

Colville 2001 

Sagavanirktok 2002

Kuparuk 2002

Trend lines from sediment data

Al (%)

0 2 4 6 8 10

As (

μg/g)

0

10

20

30

40 Sagavanirktok 2001

Kuparuk 2001

Colville 2001

Sagavanirktok 2001

Kuparuk 2001

Trend lines from sediment data

 

Figure 3-26. Concentrations of aluminum (Al) versus lead (Pb) and arsenic (As) in suspended 

sediment from the Sagavanirktok (circles), Kuparuk (triangles) and Colville

(squares) rivers for June and August 2001 and May-June 2002. Solid lines on each 

graph show regression line for Al versus metal for natural bottom sediment; dashed 

lines show corresponding 99% prediction interval.
41

TSS (mg/L)

0 100 200 300 400 500 600 700

0

4

8

12

16

Colville

Sagavanirktok

Kuparuk

5%

2%

1%

POC (mg/L)

r = 0.95

Figure 3-27. Concentrations of total suspended solids (TSS) versus particulate organic carbon 

(POC) for river suspended sediment. Solid line shows linear regression fit to the 

data with correlation coefficient (r). Dashed lines show where concentrations of 

POC are 1, 2 and 5% of the dry weight of the particles.

3.2 River Transport of Suspended Sediment, Particulate Metals and Particulate

Organic Carbon to the Coastal Beaufort Sea

The TSS and water flow data can be used to calculate sediment transport by rivers to the 

coastal Beaufort Sea. Calculations for suspended sediment transport are presented in 

more detail here for the Kuparuk and Sagavanirktok rivers because more complete data

sets for water flow are available (U.S.G.S., 1971-2001). Calculations for the Colville 

River will be based on previous estimates of sediment transport by Arnborg et al. (1967)

with an attempt to validate the earlier data using the recent, data for peak flow from 

Baker et al. (2001, 2002). Riverine transport of particulate metals and organic carbon 

also can be calculated using available data. However, exact values for transport of 

suspended sediment, particulate metals and POC by rivers to the coastal Beaufort Sea are 

presently difficult to calculate due to limitations in flow and chemical data as well as 

possible contributions from summer rainstorms. Nevertheless, by comparing transport 

during peak discharge in June with transport during the remainder of the year, a sense of 

the relative importance of spring floods to annual budgets was obtained. 

Water flow in the Sagavanirktok River for 2001 (data from U.S.G.S., 2001) was grouped 

as follows:

(1) 1.1 x 1012 L (17% of total) of peak flow during 12 days in June.

(2) 1.2 x 1012 L (18% of total) of off-peak flow during 16 days in June.

(3) 4.2 x 1012 L (65% of total) during the remaining 90 days of the water year. 
42

Concentrations of TSS averaged 267 mg/L in the Sagavanirktok River during peak

discharge in June 2001, yielding 294,000 t (metric tons), or 87% of the annual sediment 

load during the 12-day peak period. Concentrations of TSS average 31 and 1.3 mg/L 

during the off-peak period in June and the remainder of the summer, respectively,

transporting an additional 36,000 t of sediment to the coastal Beaufort Sea. A total value 

for sediment transport by the Sagavanirktok River of 0.33 Mt/yr for 2001 will be used in 

this report (Table 3-5). The final data set for flow for 2002 has not yet been released by 

the U.S.G.S. 

Particulate metal concentrations in the Sagavanirktok River did not vary greatly during 

peak and off-peak periods as shown by the standard deviations in Table 3-6; therefore, 

~87% of 6 tons of particulate Pb (Table 3-5) carried per year (for 2001) were transported 

during the 12 days of peak discharge ([0.87)(18.3 μg/g)]/[(0.15)(18.3 μg/g) + (0.87)(18.3 

μg/g] x 100%). The transport values for other particulate metals by the Sagavanirktok 

River during 2001 are given in Table 3-5. In each case, 87% of the total transport was 

during the 12 days of peak discharge in June. 

Water discharge in the Kuparuk River during 2001 (data from U.S.G.S., 2001) was 

divided into three periods: 

(1) 0.3 x 1012 L (25% of total) during three days of peak discharge in June.

(2) 0.4 x 1012 L (33% of total) during the 21 off-peak days in June. 

(3) 0.5 x 1012 L (42% of total) during the remaining 90 days of the water year 

(U.S.G.S., 1971-2001). 

Table 3-5. Amounts of suspended sediment, particulate metals and particulate organic carbon 

(POC) carried by the Sagavanirktok, Kuparuk and Colville rivers to the coastal

Beaufort Sea. 

River TSS

(Mt/yr)*

As

(t/yr)

Ba

(t/yr)

Cu

(t/yr)

Fe

(Kt/yr)

Pb

(t/yr)

Zn

(t/yr)

POC

(Kt/yr)

Sagavanirktok

(2001)

0.33 3.5 241 11 11 6 41 5

Kuparuk

(2001)

0.02 0.3 12 0.7 0.7 0.3 2.4 1

Colville 5 70 4900 200 250 120 650 110

* Mt = megatons (1 x 1012 g)
43

Table 3-6. Concentrations of particulate trace metals and particulate organic carbon (POC) in the 

Sagavanirktok, Kuparuk and Colville Rivers during June 2001. Peak and off-peak 

concentrations are presented for the Kuparuk River due to distinct differences in the 

concentrations of some trace metals during those periods. 

Calculations for annual transport of suspended sediment by the Kuparuk River also were 

based on three time periods. During the three days of peak water flow in the Kuparuk 

River in June 2001, TSS averaged 63 mg/L to yield a sediment discharge of ~19,000 t. 

During the off-peak period in June and the remainder of the summer, TSS values

averaged 4 and ~0.5 mg/L, respectively, resulting in an additional total of 1,900 t of 

sediment discharged. Thus, total discharge of suspended sediment by the Kuparuk River 

during 2001 was about 21,000 t or 0.02 Mt (Table 3-5), about 15 times less than

calculated for the Sagavanirktok River. Calculated transport of particulate metals for the 

Kuparuk River was based on the following two flow periods: (1) peak flow and (2) offpeak flow in June and the remainder of the water year because differences in

concentrations of elements in the particulate form vary between peak and low flow

periods (Table 3-6). Thus, >90% of the annual transport of 0.3 t/yr of particulate Pb 

occurred during peak flow in the Kuparuk River during three days ([(0.90)(15.7 μg/g)] 

/[(0.10)(14.4 μg/g) + (0.90)(15.7 μg/g)] x 100%). Results for transport of the other

particulate metals by the Kuparuk River (Table 3-5) show the large difference in amounts 

of particulate metals carried by the Sagavanirktok River relative to the Kuparuk River. 

In this report, we used the lower number of 5 Mt/yr for suspended sediment transport by 

the Colville River from Arnborg et al. (1967). To help validate this number, the flow 

data from Baker et al. (2001) for 6 days in June was combined with our TSS results for 

those same days. The average flow was ~6,000 m3/sec and TSS averaged ~ 500 mg/L 

(500 g/m3) to yield ~1.6 Mt of suspended sediment in 6 days [(6,000 m

3

/sec)(86,400 

River Al

(%)

Ba

(μg g-1)

Cu

(μg g-1)

Fe

(%)

Pb

(μg g-1)

Zn

(μg g-1)

POC

(%)

Sagavanirktok

(n = 17)

Mean

Std. 

Dev.

Range

5.8

± 0.8

4.0-

7.7

729

± 105

542-1008

32.9

± 2.9

29.7-39.2

3.4

± 0.3

2.6-4.0

18.3

± 2.1

16.0-23.4

124

± 8

115-135

1.60

± 0.49

0.7-2.7

Kuparuk

Peak Discharge

(n =3)

Mean

Std. 

Dev.

Range

5.2

± 0.5

4.6-

5.8

615

± 88

497-743

32.3

± 5.8

25.7-37.2

3.6

± 0.2

3.3-3.8

15.7

± 0.7

14.7-16.6

124

± 13

110-145

4.6

± 1.1

3.3-5.9

Kuparuk

Off-Peak 

Discharge

(n = 6)

Mean

Std. 

Dev.

Range

3.5

± 0.5

2.7-

4.0

469

± 70

397-559

29.9

± 1.3

28.6-31.2

3.7

± 0.3

3.1-4.2

14.4

± 8.3

4.0-22.5

92.1

± 21

69-116

4.9

± 2.0

2.8-7.6

Colville

(n = 5)

Mean

Std. 

Dev.

Range

8.3

± 0.3

8.0-

8.9

989

± 125

890-1190

40.8

± 2.3

36.9-42.6

5.0

± 0.3

4.7-5.3

24.0

± 6.8

19.8-36.0

130

± 11

116-147

2.24

± 0.56

1.7-3.3
44

sec/da)(6 da)(500 g/m3) = 1.6 x 1012 g/6 da = 1.6 Mt/6 da]. The six-day value of 1.6 Mt 

is a reasonable check on the annual value of 5 Mt used in this report based on the relative 

importance of transport of suspended sediment during peak flow by the Sagavanirktok 

and Kuparuk rivers. Data for the transport of particulate metals by the Colville River 

(Table 3-5) are based on uniform composition of the particles over the short water season 

(Table 3-6). Thus, the amounts of suspended sediment and particulate metals transported 

by the Colville River to the coastal Beaufort Sea are about 15 to 20 times greater than the 

combined amounts of the Sagavanirktok and Kuparuk rivers.

 

The calculated inputs of 0.33 million metric tons per year of suspended sediment by the 

Sagavanirktok River and 5 million metric tons of sediment per year by the Colville River

(Arnborg et al., 1967) can be used to provide perspective for the ANIMIDA project by 

comparing these river inputs with the total amount of material used to construct Northstar 

Island. About 1.6 million metric tons of sand and gravel were used construct Northstar 

Island (800,000 yd3 x 0.76 m

3

/yd3 x 2.6 metric tons/m3). Thus, annual river inputs of 

suspended sediment by the Colville River are >3 times the total amount of sand and 

gravel on Northstar Island. Annual inputs of suspended sediment from the Sagavanirktok 

River are ~15% of the complete complement of material in Northstar Island. The amount 

of material lost during and since construction of the island and pipeline is unknown, but 

certainly it must be much <10% of the total. Thus, natural inputs of suspended sediment 

to the ANIMIDA area are large relative to possible long-term releases of sediment from 

Northstar Island.

As discussed previously, the relative importance of coastal erosion to sediment loading in 

the coastal Beaufort Sea is reported to be equal to or several times greater than sediment 

inputs from river runoff (Reimnitz et al. 1988). Reimnitz et al. (1988) challenge the 

sediment runoff value of 5 million tons for the Colville River and note that variations in 

erosion processes range from erosion of 18 m of shoreline per year to accretion of 20 m 

of shoreline per year. However, the flow data of Baker et al. (2001), combined with 

levels of suspended sediment from this study, suggest that the sediment load of the

Colville River is several times greater than the value of 0.7 Mt estimated by Reimnitz et 

al. (1988). As an aside, much of the sediment transport by area rivers may be from 

erosion of the steep banks relative to physical weathering throughout the drainage basin. 

Better resolution of the relative importance of erosion versus runoff as sources of

sediment to the ANIMIDA study area is a challenge to consider in more detail during the 

upcoming continuation of the ANIMIDA program. 
45

3.4 River Water Flow Under Ice

As much as 70% of the annual sediment load of the Sagavanirktok, Kuparuk and Colville

rivers is carried to the Beaufort Sea during the two-week period of the spring floods. At 

that time, the Beaufort Sea is still covered with a 1.6- to 2-m thick layer of ice and thus 

the turbid river water flows out to sea above the ice and in a 1-2 m-thick lens of fresh 

water under the ice. This process moves a large fraction of the suspended sediment many 

kilometers offshore before settling begins and thereby contributes to the limited amount 

of modern sediment in the ANIMIDA study area. 

Samples of suspended sediment were collected under the ice, seaward of the

Sagavanirktok and Kuparuk rivers during the spring runoff of 2001 and 2002 when the 

coastal Beaufort Sea was still ice covered. Figure 3-28a shows the impact of flow from

the Sagavanirktok River on the river delta and the adjacent Endicott development. Water 

flowed seaward under the ice for more than 10 km out to sea. In Figure 3-28b, water 

flowing over the ice from the Kuparuk River was partially restrained and diverted by 

thicker ice along the ice road and pipeline route to Northstar Island.

 

(a) (b)

 

Figure 3-28. Aerial photographs from June 11, 2001 showing (a) Endicott Island with incoming 

flow from the Sagavanirktok River at top of photo and frozen sea in lower portion 

of photo and (b) incoming water from the Kuparuk River being diverted by ice 

roads to Northstar Island. 

Vertical profiles for salinity, temperature and transmissivity (e.g., Figure 3-29) show 

sharp gradients under the ice as the fresher (<6 psu), warmer (~0°C) and more turbid 

(<50% transmissivity) water mass moved over the top of the colder (-1.8°C), more salty 

(33 psu) coastal water. The vertical profiles for salinity, temperature and transmissivity 

along part of a ~8-km transect offshore (Figure 3-30) are grouped in Figures 3-31, 3-32 

and 3-33 to show the offshore movement of the freshwater mass under the ice. The layer 

of low salinity (<6 psu) water extended along a transect from station AN1 to AN7 on 

both June 9 and 11, 2001 (Figure 3-31). The layer of fresher water was slightly thicker 

with lower salinity (Figure 3-31) and higher temperature (Figure 3-32) on June 11, 

relative to June 9, as water flow neared peak levels at the U.S.G.S. gauge on June 12

(Figure 3-3, p. 19). 

River Input

River Input
46

Figure 3-29. Vertical profiles for salinity, temperature and transmissivity for station AN03 (see 

map in Figure 3-30) during under ice sampling in June 2001. The remaining

profiles are presented in Appendix B with the under ice data sets.

 Ice Layer

 (~1.6-m thick)
47

Figure 3-30. Map showing under ice and river sampling locations with concentrations of

suspended sediment in river water and in the surface layer of river water under 

the ice for June 8 and 9, 2001. 

Concentrations of TSS during the 2001 period of under-ice sampling were 177 to 203 

mg/L in the Sagavanirktok River at the PBOC bridge (Figure 3-30). Concentrations of 

TSS in the 1- to 2-m thick lens of freshwater, immediately under the ice, averaged about 

40 mg/L (Figure 3-30). The levels of TSS in the river water being carried under the ice

on June 8 and 9 (Figures 3-30 and 3-33) remained relatively high (all ~30 mg/L or more) 

because the freshwater flow was channeled for at least 10 km offshore. The channeling 

effect was set up by the flow of the lower density river water over more dense seawater 

and by the formation of a thin layer of ice at the interface of the seawater/freshwater

boundary due to freezing of the freshwater above the -1.8° C saltwater. Some settling of 

suspended sediment was observed in the transmissivity profile on June 11 at stations 

AN2 and AN3 (Figure 3-33). Settling of particles at these two sites closer to the river 

mouth (but under ice) is implied by a lack of any obvious tongues of lower salinity or 

warmer water accompanying the lower transmissivity. At distances of ~2 to 8 km along 

the transect, the suspended sediment seemed confined to the upper 1 m or so of the water 

under the ice (Figure 3-33), most likely aided by the channeling effect described above. 

PBOC Bridge: 177 mg/L (6/8/01), 203 mg/L (6/9/01) 

30 mg/L (6/8/01) 

28 and 68 mg/L 

(6/9/01) 

41 mg/L (6/8/01) 
48

Figure 3-31. Vertical profiles for salinity along a transect seaward of the Sagavanirktok River 

delta (map in Figure 3-30) for June 9 and 11, 2001. 
49

Figure 3-32. Vertical profiles for temperature along a transect seaward of the Sagavanirktok 

River delta (map in Figure 3-30) for June 9 and 11, 2001. 
50

Figure 3-33. Vertical profiles for transmissivity along a transect seaward of the Sagavanirktok 

River delta (map in Figure 3-30) for June 9 and 11, 2001. 
51

The implications of offshore transport of suspended sediment by what we have called the 

“under ice express” are potentially important to the sediment budget of the coastal

Beaufort Sea. About 87% of the annual load of suspended sediment from the

Sagavanirktok River during 2001 was carried to an ice covered coastal Beaufort Sea. 

Although some of this suspended sediment most likely was deposited in the river delta 

and in nearshore waters adjacent to the Endicott Causeway, a sizeable portion of the 

sediment was carried offshore by over and under ice transport. Such offshore movement 

of suspended sediment decreases the amount of sediment deposited along a broad portion 

of coastal Beaufort Sea, including such locations as the Boulder Patch. This observation 

is consistent with the lack of recent sediment in the ANIMIDA study area as described in 

Brown et al. (2004) and reiterated later in this report. 

Freshwater flow from the Kuparuk River could be traced to just seaward of Northstar 

Island (Figure 3-34 and map in Figure 3-30). The transect seaward of the Kuparuk River 

shows the mixing and seaward extent of the river flow in vertical profiles for salinity, 

temperature and transmissivity (Figure 3-34). The distance from shore of the terminus of 

flow from the Kuparuk River is ~10 km, about the same distance offshore as station AN5

on the transect from the Sagavanirktok River (Figure 3-30). 
52

 

Figure 3-34. Vertical profiles for salinity, temperature and transmissivity along a transect

seaward of the Kuparuk River delta for June 10, 2001. 
53

During 2002, the scenario for discharge of water from the Sagavanirktok River during 

2002 was similar to that observed in 2001 with the exception that flow was halted

temporarily due to freezing conditions, as described previously. Data from the CTDtransmissometer and samples of water and suspended sediment were collected at nine

locations during 2002 (Figure 3-35). Sampling along an L-shaped transect from the

Sagavanirktok River (Figure 3-35) was carried out on May 27, 002 and June 4, 2002. 

Turbidity in the Sagavanirktok River at the PBOC bridge peaked on May 25 and again on 

June 5, 2002 (Figure 3-12, page 25); therefore the two sampling days coincided well with 

river runoff. The salinity in the surface layer of water under the ice along the offshore 

transect from the Sagavanirktok River was <10 psu at all sites and the salinity in the 

deeper water was rather uniform at 32 psu (Figure 3-36). Temperatures in the low

salinity water under the ice were 0.2 to 0.6 °C and some slight downward mixing of 

surface water can be seen at stations S2 and S3 on June 4 (Figure 3-37). Vertical profiles 

for transmissivity on May 27 show that suspended sediment is confined to the upper layer 

(Figure 3-38) where concentrations of TSS were ~ 10 and 6 mg/L at stations S4 and S6 

(on May 28), respectively. Evidence for settling of suspended sediment is observed at 

stations S2, S3 and S5 on June 4. The values for TSS plotted on the transmissivity 

profile (Figure 3-38) for June 4 are consistent with the transmissivity data and the TSS 

data for May 27. 

At stations NS1 and NS2 on May 26, 2002, the surface water under the ice had salinity 

levels of about 10 and 30 psu, respectively (Figure 3-39). At 6 m below the surface, the 

salinity values at both stations were ~32 psu. Peak flow from the Kuparuk River

occurred on May 23 and 24. The impact of the Kuparuk River flow is very clear at

station NS1, about 4 km seaward of Northstar Island, but not at stations NS2, an

additional 1.5 km seaward of station NS1 (Figure 3-39). The concentrations of TSS track 

the salinity well at the two NS stations with values of 9.5 and 0.21 mg/L at 3 m below the 

surface for stations NS1 and NS2, respectively (Figure 3-39). At a depth of 6 m, the 

levels of TSS were ~0.2 mg/L at both NS stations. 

An overall comparison of levels of suspended sediment for the 2002 sites (Figure 3-39) 

shows that levels of TSS at 6 to 10 mg/L are common to the under ice layer of fresher 

water. Furthermore, the data for water at a water depth of 6 m along the transect from the 

Sagavanirktok River show about ten times greater levels of TSS (2 versus 0.2 mg/L) than

for similar depths at the Northstar stations. This difference is best explained by distance 

from shore and water depth. 

 
54

Figure 3-35. Map showing under ice and river sampling locations with concentrations of

suspended sediment in river water and in the surface layer of river water under 

the ice for June 2002. 
55

 

Figure 3-36. Vertical profiles for salinity along a transect seaward of the Sagavanirktok River 

delta (map in Figure 3-35) for May 27 and June 4, 2002. 
56

Figure 3-37. Vertical profiles for temperature along a transect seaward of the Sagavanirktok 

River delta (map in Figure 3-35) for May 27 and June 4, 2002. 
57

 

 

Figure 3-38. Vertical profiles for transmissivity along a transect seaward of the Sagavanirktok 

River delta (map in Figure 3-35) for May 27 and June 4, 2002. 

? 10.2

? 2.0

10.2 ?

1.4 ?

? 10.9

? 2.4

? 6.5

? 2.1
58

NS1 NS2 S4 #1 S4 #2 S6 #1 S6 #2

Salinity (psu)

0

10

20

30

40

3 m below ice, 1 m water depth

 

NS1 NS2 S4 #1 S4 #2 S6 #1 S6 #2

Salinity (psu)

0

10

20

30

40

6 m below ice, 4 m water depth

 

NS1 NS2 S4 #1 S4 #2 S6 #1 S6 #2

Total Suspended Sediment (mg/L)

0

2

4

6

8

10

12

3 m below ice, 1 m water depth 

 

NS1 NS2 S4 #1 S4 #2 S6 #1 S6 #2

Total Suspended Sediment (mg/L)

0

2

4

6

8

10

12

6m below ice, 4 m water depth

Figure 3-39. Bar graphs showing salinity and concentrations of total suspended solids for under 

ice samples from May 26, 2002 (with #1 or no extra number) and June 4, 2002 

(with #2). Stations locations shown on Figure 3-35. 

Suspended particles in the water column under the ice are generally similar in

composition to the river suspended sediment. Concentrations of Al in these under-ice 

particles ranged from ~4.2 to 7.8% and concentrations of Fe ranged from ~3.4 to 6.4% 

(Figure 3-40). The Fe/Al ratios of the under ice particles from 2002 plot above the upper 

99% prediction interval developed for bottom sediments (Figure 3-40); however, elevated 

Fe/Al ratios were found for suspended sediment from the Kuparuk River and for the 

under-ice particles collected in 2000. Under certain conditions, especially under ice or 

during periods of low TSS in the Kuparuk River, suspended particles seem to build-up 

more Fe-rich surface coatings. Dissolved Fe levels in river water during the spring floods 

are typically ten times higher than during off-peak periods and more than two-orders-ofmagnitude greater than in coastal waters (Rember and Trefry, 2004; Trefry et al., 2004). 

This abundance of dissolved Fe increases the opportunity for particles to scavenge Fe as 

the pH increases from river water to seawater and as the absolute concentrations of

particles decreases. At each site where suspended sediment were collected,

concentrations Fe in suspended sediment were 15 to 70% greater in the surface fresher 

water than in the deeper saline water (Figure 3-40). 
59

 Al (%)

0 2 4 6 8 10

Fe (%)

0

2

4

6

8

Sagavanirktok 2002

Kuparuk 2002 

2002 Shallow Under Ice Particles 

2002 Deep Under Ice Particles

Trend lines from sediment data

(a)

Particulate Fe (%)

0 2 4 6 8

Water Depth (m)

0

2

4

6

8

NS1

NS2

S4 (5/28/2002)

S4 (6/4/2002

S6 (5/28/2002)

S6 (6/4/2002)

May-June 2002

Ice (b)

 

Figure 3-40. (a) Concentrations of aluminum (Al) versus iron (Fe) in suspended sediment from 

area rivers and under ice in the Beaufort Sea during spring floods. Solid line shows

regression line for Al versus Fe for natural bottom sediment; dashed lines show 

corresponding 99% prediction interval and (b) concentrations of Fe in suspended 

sediment from under ice during May-June 2002 for stations at Northstar Island 

(NS) and the outflow of the Sagavanirktok River (S).
60

In contrast with Fe, concentrations of Ba and the Ba/Al ratios in suspended particles 

collected under the ice were similar to levels found in river suspended sediment (Figure 

3-41). As discussed in Trefry et al. (2004), concentrations of dissolved and particulate 

Ba are not influenced by changes in river flow, concentrations of TSS or dissolved

organic carbon, or minor shifts in redox conditions. Thus, the suspended sediment

collected under the ice contains Ba at levels that are similar to both incoming river

particles and bottom sediment in the coastal Beaufort Sea.

Trends for Pb (Figure 3-42), As, Cu, K, Mg, Mn and Zn follow those observed for Ba 

with metal/Al ratios for suspended sediment collected under ice that fit within the

prediction intervals developed for bottom sediments and river suspended sediment

(complete data set in Appendix B). A relatively large range in Pb content (2-3 fold) was 

observed among the under ice particles (Figure 3-42b) as the more Al-poor and organicrich particles contain less Pb. 
61

Al (%)

0 2 4 6 8 10

Ba (

μg/g)

0

200

400

600

800

1000

1200

1400

Sagavanirktok 2002

Kuparuk 2002

2002 Shallow under ice particles

2002 Deeper under ice particles

Trend lines from sediment data

(a)

 

Particulate Ba (μg/g)

0 250 500 750 1000

Water Depth (m)

0

2

4

6

8

NS1

NS2

S4 (5/28/2002)

S4 (6/4/2002

S6 (5/28/2002) May-June 2002 S6 (6/4/2002)

Ice (b)

Figure 3-41 (a) Concentrations of aluminum (Al) versus barium (Ba) in suspended sediment from 

area rivers and under ice in the Beaufort Sea during spring floods. Solid line shows 

regression line for Al versus Ba for natural bottom sediment; dashed lines show

corresponding 99% prediction interval and (b) concentrations of Ba in suspended 

sediment from under ice during May-June 2002 for stations at Northstar Island 

(NS) and the outflow of the Sagavanirktok River (S).
62

Al (%)

0 2 4 6 8 10

Pb (

μg/g)

0

10

20

30

40 Sagavanirktok 2002

Kuparuk 2002

2002 Shallow Under Ice Particles

2002 Deep Under Ice Particles

Trend lines from sediment data

(a)

Particulate Pb (μg/g)

0 10 20 30 40 50

Water Depth (m)

0

2

4

6

8

NS1

NS2

S4 (5/28/2002)

S4 (6/4/2002

S6 (5/28/2002) May-June 2002 S6 (6/4/2002)

Ice (b)

Figure 3-42 (a) Concentrations of aluminum (Al) versus lead (Pb) in suspended sediment from 

area rivers and under ice in the Beaufort Sea during spring floods. Solid line shows 

regression line for Al versus Ba for natural bottom sediment; dashed lines show

corresponding 99% prediction interval and (b) concentrations of Pb in suspended 

sediment from under ice during May-June 2002 for stations at Northstar Island 

(NS) and the outflow of the Sagavanirktok River (S).
63

3.5 Ice Cores

Ice cores were collected during April 2000 and May-June 2002 to determine the

quantities and composition of sediment trapped in the ice. This information can be used 

to identify natural trends and possible inputs of sediment to the ice from anthropogenic 

activities. Each core was subdivided into 3 to 5 sections over the 1.5 to 2 m length in the 

field. Then, each core was thawed upon return to the field laboratory, the volume

measured and the particles in the core were obtained by filtration. 

Concentrations of particles in the ice cores were highly variable, ranging from 0.3 to 248 

mg/L. In general, concentrations of particles were lowest in the deeper portions of each 

core. At depths >100 cm in the cores, the mean concentration of particles was 4 mg/L in 

2000 and 1 mg/L in 2002 with only one value in all samples from both years >3 mg/L

(Figure 3-43). In contrast, the mean value for particles in the upper 100 cm of the cores 

was 54 mg/L in 2000 and 20 mg/L in 2002. At site LA2 in 2000, for example, the values 

for sediment in the ice cores were as follows: 205 mg/L (0-55 cm), 2.6 mg/L (55-95 cm)

and 1.8 mg/L (95-155 cm) (Figure 3-43). Even at a more offshore site (NA2 in 2000)

where the absolute values were lower, the same trend was observed with values of 11 

mg/L at 0-35 cm), 3.6 mg/L at 35-70 cm, and 1.8 mg/L at 70-150 cm. Similar vertical 

trends with overall lower levels of sediment were found in 2002 (Figure 3-43). 

The distribution of sediment in the ice cores is partially consistent with the pattern of 

formation of sea ice. The top layer (as sampled) forms first and freezes in the suspended 

sediment in the ambient water. Storms during the fall seasons can keep the TSS at levels 

of >10 to 100 mg/L in the coastal Beaufort Sea. Some time after the top layer of ice

forms, the energy of the underlying water is dramatically decreased and suspended 

particles slowly settle out such that the ice that forms later from below contains

considerably lower levels of sediment. In two ice cores from 2002 (stations S4 and S6), 

one or more layers of ice with higher levels of sediment than at the top of the ice core 

were found. These deviations from the most common trend may be related to late fall 

river runoff or resuspension events. 

Data for Fe and Al in sediment from the ice cores provide some additional insight to 

differences between the composition of particles during the open-water and under-ice 

seasons. The Fe/Al ratios for sediments recovered from the top layers of the ice cores 

(0.56 ± 0.02) were consistent with the composition of suspended particles collected from 

the rivers and open water of the coastal Beaufort Sea (Fe/Al = 0.6). In contrast, the Fe/Al 

ratios for sediment collected from the lower portions of the ice cores averaged 1.6 ± 0.2. 

Particles from deeper in the ice cores were derived from the under-ice environment. 

Sediment from deeper in the ice cores had an Fe/Al ratio that was more consistent with 

the under-ice suspended particles. These results strengthen the argument that the underice particles were more Fe rich as discussed previously. 
64

30 mg/L

NA 5

Suspended Solids in Ice Cores (2000)

0

150

cm 5(5) LA 5

30

80

4 mg/L

2 mg/L

39 mg/L

1 mg/L

3 mg/L

205 mg/L

3 mg/L

2 mg/L

10 mg/L

NS1

Suspended Solids in Ice Cores (2002)

0

150

cm S4 S6

20

50

1.3 mg/L 

1.0mg/L

3.5 mg/L

0.6 mg/L

2.1 mg/L

10 mg/L

25mg/L

54 mg/L

NS2

90

1.0 mg/L

0.3 mg/L

46 mg/L

1 mg/L

15 mg/L

50 mg/L

4 mg/L

2 mg/L

Figure 3-43. Schematic profiles showing amount of sediment suspended in ice cores collected 

during 2000 and 2002 with picture showing the ice coring process.
65

The ice core data facilitate calculation of the impact of sediment releases from melting 

ice on bottom sediment accumulation. Using the worst-case scenario (site LA5, 2002), 

the integrated amount of sediment in the ice core is about 6 mg/cm2 (Figure 3-44). As the 

ice melts and releases this sediment, the impact on the seafloor is accumulation of only 

about 0.004 cm of sediment per cm2 (Figure 3-44). This small impact is consistent for all 

ice cores collected. Certainly, increased loading may be possible at some locations; 

however, the net impact on sediment accumulation would appear to be small in the

ANIMIDA study area. The average, integrated amount of suspended sediment in ice

cores (~4 mg/cm2) is larger than the calculated value of 0.3 mg/cm2 in the water under 

the ice, but generally smaller than values of 3 to 50 mg/m2 in the water column during the 

open-water period. Therefore, the overall impact of melting sea ice on suspended

sediment concentrations in the water column is minor. Furthermore, no evidence has

been found to show that the suspended sediment in these ice core samples is from other 

than natural processes. 

1 cm2

1200 cm

6 mg TSS in 

200 cm of ice

Water Column

Sediment 0.004 cm

0.006 g cm-2 / 1.6 g cm-3 = 0.004 cm 

ÿ

Ÿ

⁄

200 cm Ice

Ice melts

Figure 3-44. Schematic representation of the release of sediment from melting sea ice. The 

process is tracked as follows: 1. Integrated amount of sediment in the ice core as 

determined from core data, 2. Release of sediment to seafloor when ice melts, and 

3. Calculated depth of sediment layer formed from sediment in sea ice.
66

3.6 Suspended Sediment in Waters of Coastal Beaufort Sea

In the ANIMIDA study area, numerous vertical casts and horizontal tows in the water 

column were made during 1999, 2000, 2001 and 2002 to measure turbidity, salinity, 

temperature and current speed and direction. These data help provide a picture of the 

distribution of suspended sediment under normal and storm conditions. 

Turbidity is measured three ways, by in situ turbidimeter, by laboratory turbidimeter

using discrete samples and by filtration for total suspended solids (TSS) using discrete 

samples. The correlation between TSS and laboratory turbidity was very good (r = 0.98) 

with the overall average value for TSS in mg/L equal to ~2 times the turbidity in NTU

(Figure 3-45). Likewise, where good matches in depth of the in situ turbidimeter and the 

discrete sample were available, the relationship also was quite good (Figure 3-46). 

0 30 60 90 120

TSS (mg/L)

0

20

40

60

80

Lab Turbidity (NTU)

Total Suspended Matter vs. Turbidity

Cummulative

Turbidity = 0.51 TSS + 1.3 or

TSS = 2.0 Turbidity - 2.6

r = 0.98, n = 148

Figure 3-45. Relationship between concentrations of total suspended solids (TSS) and laboratory 

turbidity. 
67

TSS (mg/L)

0 20 40 60 80

Turbidity (NTU)

0

20

40

60

80

Lab Turbidity

In situ Turbidity 

r = 0.99

r = 0.99

Figure 3-46. Relationship for concentrations of total suspended solids (TSS) versus laboratory 

turbidity and in situ turbidity. 

Samples of suspended sediment and turbidity data were collected by way of vertical

profiles and horizontal tows during 1999, 2000, 2001 and 2002. The activity focused on 

the area of Northstar Island with selected reference sites throughout the ANIMIDA study 

area (Figure 3-47). The day-to-day distribution of TSS was dependent on river flow, 

wind conditions and sea ice. No significant differences in levels of TSS or turbidity were 

observed near Northstar Island relative to other sites in the ANIMIDA area. The details 

of the story follow below; the complete data sets are presented in Appendix C. 

Examples of typical vertical profiles for 2001 in Figures 3-48 and 3-49 show some 

typical trends. During late July and early August, 2001, winds were relatively calm and 

sea ice was close to station N1, north of Northstar Island (Figure 3-47); thus, the turbidity 

was quite low, yet higher in the surface 3 to 4 m than deeper in the water column (Figure 

3-48). The turbidity increased in samples collected closer to shore; and, in shallow 

nearshore waters at stations N13 and N14 (Figure 3-48), the water column was well

mixed and the turbidity was relatively uniform with depth. However, the absolute values 

for turbidity were still quite low at stations N13 and N14 relative to levels >50 NTU at 

the same stations immediately after the August storm of 1999. 

In the area of Liberty Prospect during 2001, the water was relatively well mixed and 

turbidity was uniform as a function of location and water depth (Figure 3-49). The

turbidity at the Liberty stations (water depths <6 m) were in the range of 5 to 8 NTU, 

similar to those in the more shallow water sites near Northstar Island, but higher than 

those in 12-m deep waters near Northstar Island. 
68

Figure 3-47. Map showing sampling stations in the ANIMIDA study area with inset maps of 

Alaska, the oil production site at Northstar Island and a possible future drilling site 

at Liberty Prospect. 

In addition to the vertical profiles, CTD-turbidity tows (Figure 3-50) were carried at a 

variety of sites, most of which were located in the area around Northstar Island. Results 

from one series of tows are presented in Figure 3-51. These results show uniform levels 

of turbidity (~2.5 NTU) just above the pycnocline at a water depth of 1.5 m on either side 

of Northstar Island. The turbidity was lower below the pycnocline at 1.2-1.5 NTU. No 

significant deviations in levels of turbidity were observed during 2002 and 2001 along 

various transects adjacent to Northstar Island at distances as close as 100-500 m (Figure 

3-51). 

Study Area

P1

.

 

..

. E1
69

Northstar, 2001

Figure 3-48. Vertical profiles for turbidity at selected sites in the area of Northstar Island during 

August 2001. Profiles extend to within 0.5 m of the bottom in each case.

4km

2km

1km

Northstar Island

Turbidity (NTU)

0 5 10

Depth (m)

0

6

12 N10

Turbidity (NTU)

0 5 10

Depth (m)

0

6

12

Turbidity (NTU)

0 5 10

Depth (m)

0

6

12

5A

Turbidity (NTU)

0 5 10

Depth (m)

0

6

12

N13

Turbidity (NTU)

0 5 10

Depth (m)

0

6

12

N14

N01
70

4km

2km

1km

Turbidity (NTU)

0 5 10

Depth (m)

0

6

12

L12

Turbidity (NTU)

0 5 10

Depth (m)

0

6

12

L08

Turbidity (NTU)

0 5 10

Depth (m)

0

6

12

4B

Turbidity (NTU)

5 10

Depth (m)

0

6

12

4A

Liberty Prospect, 2001

Figure 3-49. Vertical profiles for turbidity at selected locations in the area of Liberty Prospect. 

Profiles extend to within 0.5 m of the bottom in each case.

0
71

 Figure 3-50. Towing package with conductivity, temperature and turbidity sensors. 

The overall picture of turbidity and distribution of TSS in the coastal Beaufort Sea is a 

function of river flow, ice conditions and sea state. In the protected, relatively quiescent 

waters under ice during most of the year, levels of TSS are low at a few tenths of a

milligram per liter or lower (Table 3-7). During the brief open-water period,

concentrations of TSS were directly related to sea state that is function of the strength and 

duration of winds (Table 3-7). To obtain TSS levels >50 mg/L during the summer, a 

period of several days with winds greater than 20 knots was necessary. Likewise, levels 

of TSS <2 mg/L are observed under conditions where calm water has prevailed for 

several days; this later condition is most likely to occur when floating ice dampens wind 

effects. 

Table 3-7. Trends in concentrations of suspended sediment in the coastal Beaufort Sea as a

function of wind and ice conditions. Complete data set in Appendix C.

Trends in Total Suspended Sediment (TSS)

Under ice TSS typically 0.1 – 0.5 

mg/L

Open Water

Winds calm to 5 knots 2.5 m/sec) TSS typically 1-4 mg/L 

Winds 5-10 knots (2.5-5 m/sec) TSS typically 3-8 mg/L

10-20 knots (5-10 m/sec) TSS typically 5-15 mg/L

>20 knots (10 m/sec) TSS = 50 - >100 mg/L
72

3 & 4 1 & 2

Northstar CTD Transects

NS Tow 1

Distance (km)

0.0 0.2 0.4 0.6 0.8 1.0

Turbidity

0

1

2

3

Water depth = 1.45 ± 0.1 m

 

NS Tow 4

Distance (km)

0.0 0.2 0.4 0.6 0.8 1.0

Turbidity

0

1

2

3

Water depth = 1.49 ± 0.07 m

 

NS Tow 2

Distance (km)

0.0 0.2 0.4 0.6 0.8 1.0

Turbidity

0

1

2

3

Water depth = 5.55 ± 0.17 m

 

NS Tow 3

Distance (km)

0.0 0.2 0.4 0.6 0.8 1.0

Turbidity

0

1

2

3

Water depth = 5.30 ± 0.32 m

 

Figure 3-51. Data for turbidity (in NTU) during summer 2001 for horizontal transects upcurrent 

(Tow #3 at a water depth of ~5 m and Tow #4 at a water depth of ~1.5 m ) and 

down current (Tow #1 at a water depth of ~1.5 m and Tow #2 at a water depth of 

~5 m) at Northstar Island. Schematic map shows Northstar Island in black. The xaxis on each plot is distance in kilometers. 
73

The overview presented in Table 3-7 provides a means for interpreting observed levels of 

TSS on a day-to-day or year-to-year basis. For example, the data in Table 3-8 show a

steady trend of decreasing levels of TSS from 1999 to 2002 in the area of Northstar

Island and throughout the AMIMIDA area. Northstar Island was not constructed until 

winter 2000. However, much of the 1999 data were collected following a 5-day storm 

with >20 knot winds whereas the 2002 data, for example, were collected during calm 

conditions with considerable sea ice throughout the study area. During the 2000 and 

2001 sampling periods, conditions were moderate in the realm of 5 to 15 knot winds 

during most of the sampling times. Therefore, future assessments of the distribution of 

TSS should be presented within the context of wind conditions, sea state and the presence 

of ice that dampens wave activity. 

Table 3-8. Summary data for total suspended solids (TSS) for all stations in the ANIMIDA study 

area and for subset of stations in the area of Northstar Island.

All Stations

Year n

TSS

Mean ± SD

(mg/L)

TSS

Maximum

(mg/L)

TSS

Minimum

(mg/L)

1999 31 30 ± 27 119 2.9

2000 51 8.2 ± 4.8 26 1.7

2001 34 5.1 ± 2.1 8.7 0.9

2002 32 2.1 ± 1.3 4.4 0.2

Northstar Area

Year n

TSS

Mean ± SD

(mg/L)

TSS

Maximum

(mg/L)

TSS

Minimum

(mg/L)

1999 17 38 ± 33 119 2.9

2000 35 7.3 ± 4.0 16 1.7

2001 15 4.1 ± 1.8 6.3 0.9

2002 11 2.5 ± 1.5 4.4 0.2
74

The data in Table 3-8, coupled with the results of many vertical profiles and horizontal 

tows (Figures 3-48, 3-49 and 3-51 and Appendix C) show no significant differences in 

turbidity or concentrations of TSS in proximity (100 to 500 m) to Northstar Island

relative to other locations in the ANIMIDA study area. This result is consistent with the 

coarse-grained composition of the original sand and gravel used to construct the island 

and the armoring that covers the slope of the island to the seafloor (Figure 3-52). 

 

 

Figure 3-52. Emplacement of concrete armoring on Northstar Island during Summer 2000. 

Concentrations of Al, Fe, organic carbon and selected trace metals were determined for 

suspended matter samples collected during 2000, 2001 and 2002 (Tables 3-9, 3-10 and 3-

11). Concentrations of Al in the suspended sediment varied from 1.3% to almost 10% 

(Figure 3-53). All suspended sediment that contained <5% Al were collected when levels 

of TSS were <2 mg/L (Figure 3-53). These same samples with low levels of Al also 

contained >4% POC as a general inverse relationship was observed between POC and Al 

(Figure 3-53). All of these Al-poor, organic carbon-rich samples of suspended sediment 

were collected during 2002. Overall, levels of TSS were lowest during 2002 because the 

water was calm and sea ice had not moved very far offshore following break up. 
75

Table 3-9. Means and standard deviations (SD) for total suspended solids (TSS), turbidity (Turb.) and concentrations of metals and 

particulate organic carbon (PC) for suspended sediment collected from the coastal Beaufort Sea during August 2000.

2000

Station Grouping 

TSS

(mg/L)

Turb.

(NTU)

Al

(%)

As

(μg/g)

Ba

(μg/g)

Cd

(μg/g)

Cr

(μg/g)

Cu

(μg/g)

Fe

(%)

Pb

(μg/g)

Zn

(μg/g)

POC

(%)

North Star Area 

(n=35)

Mean

± SD

7.3

± 4.0

4.6

±2.0

7.6

±0.6

21.5

±4.2

754

±60

0.67

±0.40

109

±12

41

±7

4.4

±0.3

31

±9

158

±45

3.0

±1.4

Liberty Area 

(n=5)

Mean

± SD

10.3

± 1.6

6.7

±0.1

7.1

±0.2

16.6

±2.0

661

±21

0.57

±0.08

94

±9

36

±2

3.8

±0.2

27

±1

157

±47

2.6

±0.4

Beaufort Sea 

Monitoring 

Program 

(n=11)

Mean

± SD

9.9

± 7.3

7.1

±5.4

7.0

±0.7

19.9

±2.3

724

±61

0.67

±0.34

94

±16

38

±3

4.2

±0.3

29

±8

140

±20

2.5

±0.6

Cumulative 

(n=51)

Mean

± SD

8.2

± 4.8

5.2

±3.1

7.4

±0.7

20.6

±3.9

738

±64

0.66

±0.37

104

±14

40

±6

4.3

±0.3

30

±8

154

±41

2.8

±1.2
76

Table 3-10. Means and standard deviations (SD) for total suspended solids (TSS), turbidity (Turb.) and concentrations of metals 

and particulate organic carbon (POC) for suspended sediment collected from the coastal Beaufort Sea during August 

2001.

2001

Station Grouping 

TSS

(mg/L)

Turb.

(NTU)

Al

(%)

As

(μg/g)

Ba

(μg/g)

Cd

(μg/g)

Cr

(μg/g)

Cu

(μg/g)

Fe

(%)

Pb

(μg/g)

Zn

(μg/g)

POC

(%)

North Star Area 

(n=15)

Mean

± SD

4.1

±1.8

3.9

±1.8

8.8

±0.6

24.7

±2.5

814

±39

0.51

±0.18

109

±8

49

±6

5.2

±0.3

27

±2

137

±40

3.7

±1.3

Liberty Area 

(n=6)

Mean

± SD

6.5

±1.1

6.7

±1.2

6.5

±0.3

22.1

±3.4

724

±19

0.39

±0.14

103

±5

48

±10

4.0

±0.2

28

±1

126

±16

2.9

±0.1

Beaufort Sea 

Monitoring 

Program 

(n=13)

Mean

± SD

5.5

±2.2

5.5

±2.3

7.8

±1.0

17.0

±2.6

754

±61

0.50

±0.15

118

±8

45

±5

4.8

±0.5

27

±5

129

±19

3.9

±1.0

Cumulative

(n=34)

Mean

± SD

5.0

±2.1

5.0

±2.2

8.0

±1.1

21.3

±4.4

775

±58

0.49

±0.16

111

±9

48

±6

4.8

±0.6

27

±4

132

±30

3.6

±1.1
77

Table 3-11. Means and standard deviations (SD) for total suspended solids (TSS), turbidity (Turb.) and concentrations of metals and 

particulate organic carbon (POC) for suspended sediment collected from the coastal Beaufort Sea during August 2002.

2002

Station Grouping 

TSS

(mg/L)

Turb.

(NTU)

Al

(%)

As

(μg/g)

Ba

(μg/g)

Cd

(μg/g)

Cr

(μg/g)

Cu

(μg/g)

Fe

(%)

Pb

(μg/g)

Zn

(μg/g)

POC

(%)

North Star Area 

(n=11

Mean

± SD

2.5

±1.5

2.4

±1.3

6.3

±0.7

23.4

±2.9

591

±174

0.75

±0.30

86.5

±14

37

±5

4.3

±0.3

21

±3

100

±10

3.2

±2.4

Beaufort Sea 

Monitoring 

Program 

(n=21)

Mean

± SD

1.9

±1.2

2.0

±1.1

5.7

±1.4

30.0

±6.7

550

±168

0.71

±0.31

79

±21

40

±7

4.0

±0.6

20

±5

104

±14

4.1

±2.1

Cumulative

(n=32)

Mean

± SD

2.1

±1.3

2.1

±1.2

5.9

±1.2

2.73

±6.5

564

±168

0.72

±0.30

82

±19

39

±7

4.1

±0.5

21

±4

103

±13

3.8

±2.1
78

Al (%)

0 2 4 6 8 10

TSS (mg/L)

0

5

10

15

20

25

30

2000

2001

2002

Al (%)

0 2 4 6 8 10

POC (%)

0

2

4

6

8

10

2000

2001

2002

Figure 3-53. Concentrations of Al versus total suspended solids (TSS) and particulate organic 

carbon (POC) for suspended sediment from the coastal Beaufort Sea.
79

Al (%)

0 2 4 6 8 10 12

Fe (μg/g)

0

2

4

6

8

Suspended Sediment

2000

2001

1999

2002

Trend lines from data 

for bottom sediment

 Al (%)

0 2 4 6 8 10 12

Ba (μg/g)

0

200

400

600

800

1000

1200

Suspended Sediment

2000

2001

2002

1999

Trend lines from data 

for bottom sediment

Al (%)

0 2 4 6 8 10 12

Cr (μg/g)

0

50

100

150

200

Suspended Sediment

2000

2001

1999

2002 Trend lines from data 

for bottom sediment

 Al (%)

0 2 4 6 8 10

Zn (μg/g)

0

40

80

120

160

Suspended Sediment

2000

2001

2002 

5E

Figure 3-54. Concentrations of aluminum (Al) versus iron (Fe), barium (Ba), chromium (Cr) and 

zinc (Zn) for suspended sediment from the coastal Beaufort Sea during 1999, 2000, 

2001 and 2002. Solid lines show linear regression fit to data and dashed lines show 

99% prediction intervals.

Concentrations of Fe in the suspended sediment correlated relatively well with Al; and all 

data points, except most of those from 2002, plotted within the 99% prediction interval 

established for bottom sediments (Figure 3-54). The Fe-enrichment observed for 2002 is 

consistent with what was observed for under-ice particles. During 2002, we were most 

likely sampling many residual under-ice particles and the products of recent biological 

productivity. In contrast with Fe, concentrations of Ba and Cr in the suspended sediment

from all four summer samplings, including 2002, plotted within the prediction intervals 

for Ba/Al and Cr/Al for bottom sediments (Figure 3-54). Both Ba and Cr are not

enriched in biological materials (e.g., plankton) or under-ice particles, therefore, the

Ba/Al and Cr/Al ratios in the suspended sediment fit the relationship developed for

bottom sediments. 

Concentrations of Zn were generally within or below the Zn/Al prediction interval based 

on bottom sediments (Figure 3-54). No explanation for the Zn values that plotted below 

the 99% prediction interval for sediments is available at this time. The data for

particulate Zn in Figure 3-54 are from surface samples collected carefully from the front 

of a Zodiac slowly moving upcurrent or upwind or by pumping water from the Zodiac 
80

using a peristaltic pump and acid-washed tubing. During 2000, some surface and subsurface samples appear to have been contaminated during sampling from the MMS 

Launch 1273 and that practice was discontinued in 2001 and 2002. The data for one 

sample that plot above the upper prediction interval in Figure 3-54 may be due to the 

abundant, more Zn-rich plankton in that sample or to anthropogenic inputs as described 

in the discussion of Cu, Cd, Pb and As below. 

Nine sample points from 2002 on the Al versus Cu graph plotted above the upper

prediction interval developed from data for bottom sediments. A similar trend was

observed for Cd and As, but not distinctly for Pb in the 2002 samples (Figure 3-55). 

These anomalous samples were low with respect to TSS and generally enriched with 

respect to POC. Copper, Cd and As are often enriched in plankton relative to sediments. 

Enrichment of Cu, Cd and As in the organic-rich samples from 2002 is consistent with a 

planktonic source. 

In contrast, concentrations of Pb (like Ba and Cr) are generally low in plankton and thus 

the positive anomalies on the Pb/Al graph were fewer in number. However, Pb levels in 

suspended sediment at several stations near Northstar Island during 2000 and one during 

2001 were enriched with Pb relative to values observed for bottom sediment (Figure 3-

 

Al (%)

0 2 4 6 8 10 12

Cu (μg/g)

0

10

20

30

40

50

60

Suspended Sediment

2000

2001

2002

Trend lines from data 

for bottom sediment

Al (%)

0 2 4 6 8 10 12

Cd (μg/g)

0.0

0.5

1.0

1.5

2.0

Suspended Sediment 2000

2001 

2002 

Trend lines from data 

for bottom sediment

Al (%)

0 2 4 6 8 10 12

Pb (μg/g)

0

10

20

30

40

Suspended Sediment

2000

2001

1999

Trend lines from data 2002

for bottom sediment

N5

NSX

N10

5B

 Al (%)

0 2 4 6 8 10 12

As (μg/g)

0

10

20

30

40

Suspended Sediment 2000

2001 

2002

Figure 3-55. Concentrations of aluminum (Al) versus copper (Cu), cadmium (Cd), lead (Pb) and 

arsenic (As) for suspended sediment from the coastal Beaufort Sea during 1999 

(triangles), 2000 (squares) and 2001 (+ signs). Solid lines show linear regression fit 

to data and dashed lines show 99% prediction intervals.
81

55). The few surface samples of TSS with Pb levels that were 20-50% above the upper 

prediction interval in Figure 3-55 were collected as near as 100 m from Northstar Island. 

This apparent enhancement in Pb levels in the few samples of suspended sediment may 

be the result of uptake of anthropogenic Pb on the small levels of particles (2-6 mg/L) in 

the water column. The apparent anomalies may be detected because Pb is readily

adsorbed to particles and because the low levels of TSS magnify the apparent enrichment 

of Pb. However, as suggested above for the anomalous data points for Cu, Cd and As, 

additional analyses of plankton and continued assessment of background levels of metals 

in suspended sediment are required before the metal/Al ratios in suspended sediment can 

be as useful as previously demonstrated for bottom sediment (Trefry et al., 2003). 

3.7 Sediment Accumulation

The final chapter in the story of suspended sediment that began in the mountains during 

spring is the deposition of these particles as bottom sediment in the Beaufort Sea. As 

detailed in Brown et al. (2004), the accumulation of modern sediments in the ANIMIDA 

study area is patchy. Results show that sedimentation rates range from ~0.04 cm/yr to 

~0.10 cm/yr with several sites having little or no net accumulation of sediment during at 

least the past 50 years (Figure 3-56). At three sites, only 3- to 5-cm thick layers of 

sediment were deposited since development began during the 1960s. Overall, these 

results are consistent with those of Naidu et al. (2001) for the same area. The presence of 

fine-grained sediment at a given location can vary from year to year and sedimentary 

processes along much of the shallow, coastal Beaufort Sea are quite dynamic. 

Additional support for low sedimentation rates at stations P01 and E01 can be developed 

from data for river inputs of sediment. The Sagavanirktok River, the major river carrying 

sediment into the area near stations P01 and E01, is estimated to have an annual sediment 

load of about 6 x 105 metric tons. The depositional area for this sediment in coastal

Beaufort Sea is about 1000 km2 to yield an estimated deposition rate of ~0.04 cm/y based 

on a sediment bulk density of 1.6 g/cm3 ([0.6 x 10

12 g dry sediment/10 x 1012 cm2

] x [(1.6 

g wet sediment/cm3)/(2.6 g dry sediment/cm3)]). As previously noted, however, the

coastal Beaufort Sea in this area may be net erosional at this time (Reimnitz and Wolf, 

1998). Based on our observations, much of the large sediment load of the rivers must be 

carried across the nearshore environment during spring on the freshwater channel under 

the ice to be deposited in deeper waters of the Beaufort Sea. Therefore, sediment

monitoring for contaminants must be coordinated with measurements of radionuclides 

such as 137Cs, excess 210Pb, 234Th or 7Be in sediments to ensure that samples are recent 

and not relict deposits. 
82

Sedimentation Rates in cm/yr

P01~0.10

~0

~0

~0

~0

E01~0.05

6G~0.05

~0.1

~0

Figure 3-56. Sedimentation rates for the coastal Beaufort Sea based on data for 137Cs and excess 

210Pb.
83

4.0 SUMMARY AND CONCLUSIONS

Rivers are an important source of water and suspended sediment to the study area during 

the period of spring runoff and on an annual basis. For example, concentrations of TSS

in the Sagavanirktok River near the Prudhoe Bay Operations Center increased from ~40 

mg/L on June 1 when flow began to 600 mg/L on June 12, 2001, and then decreased to 

~30 mg/L by June 18. During late July and August 2001, concentrations of TSS were 

only ~2 mg/L. Concentrations of TSS followed similar trends for the Colville River with 

maximum levels of about 600 mg/L on June 13, 2001. In contrast, concentrations of TSS 

reached peak values of only 60 mg/L in the Kuparuk River on June 10, 2001 and

decreased to <5 mg/L after June 16, 2001. Peak flow recorded for the Kuparuk River 

was about 600 m3/sec on June 12, 2001, decreasing to <50 m3/sec after June 28, 2001. 

During 2002, the same trend of increasing concentrations of TSS was observed; however, 

freezing temperatures led to refreezing of the rivers and put a hiatus in the spring flood 

for the Sagavanirktok River. However, the dramatic two-day flood of the Kuparuk River 

in 2002 occurred during the period prior to refreezing. 

For the Sagavanirktok River, the calculated annual sediment transport was ~0.33 million 

metric tons for 2001, with ~87% of the annual transport of suspended sediment occurring 

during just 12 days in June. Total transport of suspended sediment by the Kuparuk River 

was 0.02 million metric tons for 2001 with ~90% of the annual sediment load of the river 

being carried during just three days in June. Previous estimates for the Colville River of 

5 million metric tons of sediment per year are supported by recent measurements during 

high flow. These natural inputs by rivers can be compared with ~1.6 million metric tons 

of sand and gravel used to construct Northstar Island [(800,000 yd3 x 0.76 m3/yd3 x 2.6 

metric tons/m3 = 1.6 million metric tons). Coastal erosion also is an important source of 

sediment to the coastal Beaufort Sea, including the ANIMIDA study area. Estimates 

from previous studies state that coastal erosion may contribute sediment to the coastal

Beaufort Sea at levels that are equal to or several times greater than inputs of sediment by 

rivers. 

River runoff during the spring floods is carried to a coastal Beaufort Sea that is covered 

with 2-m thick ice. Concentrations of TSS averaged ~40 mg/L in a 2-m thick lens of 

freshwater immediately under the ice that extended >10 km offshore. The suspended

sediment was very rich in fine-grained aluminosilicates as shown by the levels of Al and 

other metals in the particles. Metal/Al ratios in suspended particles collected under the 

ice showed that the composition of river-borne particles was similar to that found for

bottom sediment. 

During the open-water period in 1999-2002, the day-to-day turbidity and distribution of 

TSS in the coastal Beaufort Sea were dependent on river flow, ice cover and sea state. In 

the protected, relatively quiescent waters under ice during most of the year, levels of TSS 

were low at a few tenths of a milligram per liter relative to average levels of ~40 mg/L in 

surface waters under the ice during the spring floods. During the brief open-water period, 

after the spring floods, concentrations of TSS were typically <20 mg/L and varied as a 

function of sea state and the presence of floating sea ice. Sea state was directly related to 
84

the strength and duration of winds. Concentrations of TSS increased to >50 mg/L during 

the summer only following a period of several days with winds greater than 20 knots. In 

contrast, levels of TSS <2 mg/L were observed under conditions where calm water had 

prevailed for several days. This later condition was most likely to occur when floating 

ice dampened any wind effects. No significant deviations in levels of turbidity were

observed adjacent to Northstar Island during 2000-2002 while towing a turbidimeterCTD package along transects at distances as close as 100-500 m from the island. 

The chemical composition of river suspended sediment was compared with results for 

bottom sediment to help identify possible anthropogenic inputs of suspended sediment or 

contaminant metals to the coastal environment. Differences in the elemental composition 

of suspended sediment were observed among rivers. The Colville River contained

greater amounts of particulate Al, Fe and trace metals relative to the more Ca-rich 

particles of the Sagavanirktok River and the more organic carbon-rich particles of the

Kuparuk River. However, the metal/Al ratios for all elements, except Ca, were not

significantly different among rivers and bottom sediment from the coastal Beaufort Sea. 

Concentrations of trace metals also were determined for samples of suspended matter 

collected from the coastal Beaufort Sea. The fine-grained aluminosilicates suspended in 

the water column were enriched with Al and trace metals. However, concentrations of 

most metals in suspended sediment for 2000 and 2001 plotted within the 99% prediction 

intervals for metals versus Al that were developed using data for bottom sediment. Thus, 

in most instances, concentrations of trace metals associated with suspended particles were 

within the limits established for uncontaminated sediment. Suspended particles are

potentially a more sensitive indicator of recent metal contamination than sediment

because the small amounts of suspended particles typically found in the water column 

lead to a larger relative enrichment of anthropogenic metal concentrations. This

sensitivity was demonstrated with several samples of suspended sediment that were

collected very near Northstar Island during construction in August 2000 and contained Pb 

at levels that were 20-50% above background. 

With respect to sedimentation, the ANIMIDA area appears to be a net erosional

environment at this time. Based on our observations, much of the large sediment load of 

the rivers is carried across the nearshore environment to deeper waters of the Beaufort 

Sea along a freshwater channel under the ice during spring or with summer and fall

storms. Therefore, sediment monitoring for contaminants must be coordinated with

measurements of radionuclides such as 137Cs, excess 210Pb, 234Th or 7Be that help ensure 

that samples are recent and not relict deposits.

Overall, no significant differences in concentrations of TSS that could be directly linked 

to oil and gas operations were observed in the ANIMIDA area. Periodic enhancement in 

levels of TSS in the coastal Beaufort Sea can be related to river runoff and resuspension 

of bottom sediment by strong winds. Natural inputs of suspended sediment from runoff 

and erosion are large relative to any anthropogenic inputs of sediment. 

 
85

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characterization of sediments, bivalves and amphipods in the ANIMIDA study 

area. Final Report to MMS, OCS Study MMS2004-24.

Craig, P.C. and McCart, P.J. (1975) Classification of stream types in Beaufort Sea

drainage basins between Prudhoe Bay, Alaska, and the Mackenzie delta, N.W.T., 

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87

The Department of the Interior Mission

As the Nation's principal conservation agency, the Department of the Interior has responsibility for most of our 

nationally owned public lands and natural resources. This includes fostering sound use of our land and water 

resources; protecting our fish, wildlife, and biological diversity; preserving the environmental and cultural values of 

our national parks and historical places; and providing for the enjoyment of life through outdoor recreation. The 

Department assesses our energy and mineral resources and works to ensure that their development is in the best 

interests of all our people by encouraging stewardship and citizen participation in their care. The Department also 

has a major responsibility for American Indian reservation communities and for people who live in island territories 

under U.S. administration.

The Minerals Management Service Mission

As a bureau of the Department of the Interior, the Minerals Management Service's (MMS) primary responsibilities 

are to manage the mineral resources located on the Nation's Outer Continental Shelf (OCS), collect revenue from 

the Federal OCS and onshore Federal and Indian lands, and distribute those revenues.

Moreover, in working to meet its responsibilities, the Offshore Minerals Management Program administers the 

OCS competitive leasing program and oversees the safe and environmentally sound exploration and production of 

our Nation's offshore natural gas, oil and other mineral resources. The MMS Royalty Management Program

meets its responsibilities by ensuring the efficient, timely and accurate collection and disbursement of revenue from 

mineral leasing and production due to Indian tribes and allottees, States and the U.S. Treasury.

The MMS strives to fulfill its responsibilities through the general guiding principles of: (1) being responsive to the 

public's concerns and interests by maintaining a dialogue with all potentially affected parties and (2) carrying out its 

programs with an emphasis on working to enhance the quality of life for all Americans by lending MMS assistance 

and expertise to economic development and environmental protection.

6.0 LIST OF APPENDICES

The appendices listed below are tabulated on the CD attached to hard copies of this report 

or as separate files on this CD.

Appendix A: Data for Suspended Sediment from Rivers for 2001 and 2002

Appendix B: Data for Suspended Sediment Under Ice for 2001 and 2002

Appendix B1: CTD Under Ice for 2001

Appendix B2: CTD Under Ice for 2002 

Appendix C: Data for Suspended Sediment Offshore for 2000, 2001 and 2002

Appendix C1: Aanderaa Data for Summer 1999-2002
88