The front and back covers show an aerial photomosaic of the Kahuku coastal plain, including the 

Punamano and Kii Units of the James Campbell National Wildlife Refuge. (Photography by Air 

Survey Hawaii. Photomosaic created by joining two digitally scanned, false-color infrared 

photographic prints furnished by the U.S. Fish and Wildlife Service, Haleiwa, Hawaii, dated 

February 2, 1991, and January 9, 1992.) 
U.S. Department of the Interior

Hydrology and Water and Sediment Quality at

James Campbell National Wildlife Refuge near

Kahuku, Island of Oahu, Hawaii

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 99-4171

Prepared in cooperation with the

U.S. FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR
Hydrology and Water and Sediment Quality at

James Campbell National Wildlife Refuge near

Kahuku, Island of Oahu, Hawaii

By Charles D. Hunt, Jr., and Eric H. De Carlo

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 99-4171

Prepared in cooperation with the

U.S. FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR

Honolulu, Hawaii

2000
U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

The use of firm, trade, and brand names in this report is for identification purposes

only and does not constitute endorsement by the U.S. Geological Survey.

For additional information write to: Copies of this report can be purchased

from:

District Chief U.S. Geological Survey

U.S. Geological Survey Branch of Information Services

677 Ala Moana Blvd., Suite 415 Box 25286

Honolulu, HI 96813 Denver, CO 80225-0286

U. S. DEPARTMENT OF THE INTERIO

R

MARCH 3, 1849
Contents iii

CONTENTS

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Purpose and Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Description of the Study Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Physiography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Climate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Land Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Data-Collection Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Surface-Water Stations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Meteorology Stations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Ground-Water Stations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Water- and Sediment-Quality Stations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Streamflow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Water-Level Fluctuations in the Gaged Surface-Water Bodies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Runoff Volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Observations Related to Stormflows and Flooding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Storms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Stream Response Times and Stream Gradients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Sea-Level Interactions and Potential Backwater Effects in Lowland Areas . . . . . . . . . . . . . . . . . . . . . . . . 33

Ground-Water/Surface-Water Interaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Regional-Scale Hydrogeology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Principal Hydrogeologic Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Sedimentary Depositional Sequence and Paleoenvironment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Nature of Ground-Water Discharge from the Koolau Aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Contributions to Ditch Base Flow from Surficial Sediments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Pond-Scale Hydrogeology of the Punamano and Kii Units. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Ground-Water and Surface-Water Salinity at Kii Unit Piezometers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Ground-Water/Surface-Water Interaction at Kii Unit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Regional Salinity Survey and Reconnaissance for Ground-Water Seepage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Salinity at Punamano Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Salinity at Kii Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Previous Salinity Observations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Potential Migration of Wastewater from the Kahuku Injection Wells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Water Budgets for the Punamano and Kii Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Water-Budget Equations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Required Data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Results of the Water Budgets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Relation of the Budget Period to Long-Term Average Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Water and Sediment Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Water and Sediment Sampling and Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
iv Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

Inorganic Chemical Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Inorganic Water Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Inorganic Sediment Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Organic Chemical Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Organic and Nutrient Water Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Organic Sediment Chemistry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Sediment Mineralogy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

Comparison of Trace-Element and Organic Compound Concentrations in Water and Bottom Sediment

with Water-Quality Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Water. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Pond-Bottom Sediment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Summary and Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

References Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

Figures

1–3. Maps showing:

1. James Campbell National Wildlife Refuge and surrounding area near the town of Kahuku in

northern Oahu, Hawaii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2. Punamano Unit of James Campbell National Wildlife Refuge, Oahu, Hawaii . . . . . . . . . . . . . . . . . . . . . 5

3. Kii Unit of James Campbell National Wildlife Refuge, Oahu, Hawaii. . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4. Diagram showing simplified geology and modes of ground-water/surface-water interaction at

Punamano and Kii Units, James Campbell National Wildlife Refuge, Oahu, Hawaii . . . . . . . . . . . . . . . . . 8

5–9. Maps showing:

5. Streams and selected surface drainage boundaries in the vicinity of James Campbell National

Wildlife Refuge, Oahu, Hawaii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

6. Primary network of surface-water and meteorologic stations, James Campbell National Wildlife

Refuge, Oahu, Hawaii (also included in the primary network is rain gage station 9 shown on figure 5) 16

7. Supplemental surface-water stations and benchmarks at the Kii Unit, James Campbell National

Wildlife Refuge, Oahu, Hawaii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

8. Ground-water stations at the Kii Unit, James Campbell National Wildlife Refuge Oahu, Hawaii. . . . . . . 19

9. Sites sampled for inorganic and chemical analysis of water and pond-bottom sediment, James

Campbell National Wildlife Refuge, Oahu, Hawaii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

10–15. Graphs showing:

10. Water-level hydrographs for stations 2, 3, and 5 and daily rainfall at station 9, October 1996 to

January 1998, James Campbell National Wildlife Refuge, Oahu, Hawaii . . . . . . . . . . . . . . . . . . . . . . . 23

11. Water-level hydrographs for stations 1, 7, 8, 21, and 36, and daily rainfall at station 9, October

1996 to January 1998, James Campbell National Wildlife Refuge, Oahu, Hawaii . . . . . . . . . . . . . . . . 24

12. Water-level hydrographs at stations 2, 3, 5, 8, and 36, and 10-minute rainfall at station 9,

November 1996, James Campbell National Wildlife Refuge, Oahu, Hawaii. Also shown are

hourly mean sea level at Kaneohe tide gage, and daily North Shore surf height . . . . . . . . . . . . . . . . . . 30

13. Water-level hydrographs for stations 2, 3, and 5, and 10-minute rainfall at station 9, January 1997,

James Campbell National Wildlife Refuge, Oahu, Hawaii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

14. Water-level hydrographs for stations 1, 7, 8, and 36, and 10-minute rainfall at station 9, January 1997,

James Campbell National Wildlife Refuge, Oahu, Hawaii. Also shown are hourly mean sea level at

Kaneohe tide gage and daily North Shore surf height . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Contents v

15. Stream, ocean, and pumping influences on Kii ocean outlet for the 16-month period November 1996

through February 1998, James Campbell National Wildlife Refuge, Oahu, Hawaii. Shown are

water-level hydrographs for stations 3, 7, and 8, hourly mean sea level at Kaneohe tide gage, and

daily North Shore surf height . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

16. Map showing geology of the Kahuku area with locations of wells and lines of hydrogeologic cross

sections near James Campbell National Wildlife Refuge, Oahu, Hawaii . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

17. Hydrogeologic cross sections of the Kahuku area near James Campbell National Wildlife Refuge, Oahu,

Hawaii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

18–19. Graphs showing:

18. Ground-water levels in piezometers and surface-water levels in overlying ponds and ditches,

September 1997 to January 1998, at Kii Unit, James Campbell National Wildlife Refuge, Oahu, Hawaii 46

19. Daily mean ground-water and surface-water levels in piezometers and overlying ponds and ditches,

September 1997 to January 1998, at Kii Unit, James Campbell National Wildlife Refuge, Oahu, Hawaii 47

20–21. Maps showing:

20. Specific conductance of surface-water bodies in and near Punamano Unit, James Campbell National

Wildlife Refuge, Oahu, Hawaii, November 12–14, 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

21. Specific conductance of surface-water bodies in and near Kii Unit, James Campbell National Wildlife

Refuge, Oahu, Hawaii, November 12–14, 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

22. Diagram showing terms in the water budgets for Punamano and Kii Units, James Campbell National

Wildlife Refuge, Oahu, Hawaii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Tables

 1. Drainage areas in the vicinity of the James Campbell National Wildlife Refuge, Oahu, Hawaii . . . . . . . . . . . . . . . 12

 2. Fixed data-collection stations and benchmarks included in the hydrologic and meteorologic data network at

James Campbell National Wildlife Refuge, Oahu, Hawaii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

 3. Water and sediment samples collected for organic and inorganic chemical analyses, James Campbell National

Wildlife Refuge and vicinity, Oahu, Hawaii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

 4. Monthly discharge of streams and ditches flowing in and out of the coastal plain near the James Campbell

National Wildlife Refuge, Oahu, Hawaii, October 1996 through December 1997 . . . . . . . . . . . . . . . . . . . . . . . . 26

 5. Peak stage, discharge, and time to peak stage at surface-water gaging stations during storms in November

1996 and January 1997, James Campbell National Wildlife Refuge, Oahu, Hawaii . . . . . . . . . . . . . . . . . . . . . . . 28

 6. Flood peaks, hydraulic head drop, and average gradient from stations to inner ditch terminus station 7 at Kii Unit

during storms in January 1997, James Campbell National Wildlife Refuge, Oahu, Hawaii . . . . . . . . . . . . . . . . . 34

 7. Flood peaks, hydraulic head drop, and average gradient from respective stations to Kii ocean outlet station 8

during storms in November 1996 and January 1997, James Campbell National Wildlife Refuge, Oahu, Hawaii 35

 8. Logs of driven ground-water piezometers at the Kii Unit, James Campbell National Wildlife Refuge, Oahu,

Hawaii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

 9. Ground-water and surface-water levels at selected stations on September 5, October 7, and December 10, 1997,

James Campbell National Wildlife Refuge, Oahu, Hawaii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

 10. Specific conductance in ground-water piezometers and overlying surface-water bodies at Kii Unit, James

Campbell National Wildlife Refuge, Hawaii, November 14, 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

 11. Specific conductance and temperature of surface and ground waters on the Kahuku coastal plain in and near

James Campbell National Wildlife Refuge, November 12–14, 1997. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

 12. Sources of water to ponds at Kii Unit, and specific conductance in the ponds and in the Kii artesian wells,

November 14, 1997, James Campbell National Wildlife Refuge, Hawaii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

 13. Surface areas of ponds and wetlands, James Campbell National Wildlife Refuge, Hawaii . . . . . . . . . . . . . . . . . . . . 60
vi Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

 14. Monthly rainfall in the Kahuku uplands, and rainfall and potential evaporation at the Kii Unit, James Campbell

National Wildlife Refuge, Oahu, Hawaii, 1995–97 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

 15. End-of-month water levels in ponds at James Campbell National Wildlife Refuge, Oahu, Hawaii, December

1996 through December 1997 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

 16. Monthly water budget for the Punamano Unit, James Campbell National Wildlife Refuge, Oahu, Hawaii, 1997 . . 63

 17. Monthly water budget for the Kii Unit, James Campbell National Wildlife Refuge, Oahu, Hawaii, 1997 . . . . . . . . 63

 18. Major-element and trace-element composition of pond-bottom sediments, James Campbell National Wildlife

Refuge, Hawaii, December 28, 1994 (dry season) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

 19. Major-ion concentrations in surface and ground waters in the vicinity of James Campbell National Wildlife

Refuge, Hawaii, November 22, 1994 (dry season) and March 13–14, 1997 (wet season) . . . . . . . . . . . . . . . . . . 68

 20. Trace-element concentrations in surface and ground water near James Campbell National Wildlife Refuge,

Hawaii, November 22, 1994 (dry season) and March 13–14, 1997 (wet season) . . . . . . . . . . . . . . . . . . . . . . . . . 69

 21. Organic compounds and nutrients in surface and ground waters near James Campbell National Wildlife Refuge,

Hawaii, November 22, 1994 (dry season) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

 22. Organic compounds and nutrients in surface and ground water near James Campbell National Wildlife Refuge,

Hawaii, March 13–14, 1997 (wet season) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

 23. Organic compounds in pond-bottom sediments at James Campbell National Wildlife Refuge, Oahu, Hawaii,

December 28, 1994 (dry season) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

Temperature in degrees Celsius (°C) may be converted to degrees Fahrenheit (°F) as follows:

°F=1.8°C+32

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C=(F−32)/1.8

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (μS/cm at 25°C).

Concentrations of chemical constituents and sediment in water are given either in milligrams per liter (mg/L), micrograms

per liter (μg/L), or micrograms per kilogram (μg/kg).

Conversion Factors

Multiply By To obtain

acre 4,047 square meter

foot (ft) 0.3048 meter

foot per day (ft/d) 0.3048 meter per day

foot per mile (ft/mi) 0.1894 meter per kilometer

cubic foot per second (ft3/s) 0.02832 cubic meter per second

inch (in.) 2.54 centimeter

inch per year (in/yr) 2.54 centimeter per year

inch per day (in/d) 2.54 centimeter per day

mile (mi) 1.609 kilometer

gallons per minute (gal/min) 3.785 liters per minute

gallons per day (gal/d) 3.785 liters per day

million gallons (Mgal) 0.04381 cubic meters
Hydrology and Water and Sediment Quality at James

Campbell National Wildlife Refuge near Kahuku, Island of

Oahu, Hawaii

By Charles D. Hunt, Jr., and Eric H. De Carlo

Abstract 1

Abstract

The James Campbell National Wildlife Refuge occupies two lowland marsh and pond complexes on the northern coastal plain of Oahu: the

mostly natural ponds and wetlands of the

Punamano Unit and the constructed ponds of the

Kii Unit. The U.S. Fish and Wildlife Service manages the Refuge primarily to protect and enhance

habitat for four endangered species of Hawaiian

waterbirds. Kii Unit is fed by artesian wells and

rainfall, whereas Punamano Unit is fed naturally by

rainfall, runoff, and ground-water seepage.

Streams drain from the uplands into lowland

ditches that pass through Kii Unit on their way to

the ocean. A high-capacity pump transfers water

from the inner ditch terminus at Kii to the ocean

outlet channel. Stormwaters also exit the inner

ditch system over flood-relief swales near the outlet pump and through a culvert with a one-way

valve.

A hydrologic investigation was done from

November 1996 through February 1998 to identify

and quantify principal inflows and outflows of

water to and from the Refuge, identify hydraulic

factors affecting flooding, document groundwater/surface-water interactions, determine the

adequacy of the current freshwater supply, and

determine water and sediment quality. These goals

were accomplished by installing and operating a

network of stream-gaging stations, meteorology

stations, and shallow ground-water piezometers,

by computing water budgets for the two Refuge

units, and by sampling and analyzing water and

pond-bottom sediments for major ions, trace metals, and organic compounds.

Streamflow during the study was dominated

by winter stormflows, followed by a gradual recession of flow into summer 1997, as water that had

been stored in alluvial fans drained to lowland

ditches. Outflow at the ditch terminus in 1997 was

125 million gallons greater than measured inflow

to the coastal plain, mainly reflecting gains from

ground water along the ditches between outlying

gages and the ditch terminus. Of the measured

1997 outflow, 98 percent was through the Kii outlet

pump, with the outlet culvert valve only opening

for brief periods during storms. Large volumes of

stormflow overflowed the flood-relief swales

unmeasured.

The largest storm of the study, in November

1996, was estimated to have a flood frequency of

about 3 to 4 years. Streamflow exceeded culvert

capacity and overtopped Kamehameha Highway at

Kalaeokahipa Stream and Hospital ditch. Slight

overbank flooding in Kii ditch resulted strictly

from high discharge. Minor overbank flooding farther out on the coastal plain probably was caused

mainly by the small hydraulic gradients available

to convey stormflows along the lowland ditches.

Stormwaters flooded Kii ponds and flowed back

upstream along Punamano ditch into Punamano

marsh, introducing suspended sediment and possibly other contaminants to the Refuge. Two smaller

storms in January 1997 resulted in smaller flows

and no overbank flooding. The Kii outlet pump ran

continuously for 7 days during the November 1996

storm and for 1 to 2 days during the January 1997
2 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

storms. During all three storms, the outlet culvert

valve opened and the inner ditches overtopped the

flood-relief swales, allowing free outflow of water

from the inner ditch.

Backwater effects hindered drainage during

the January 1997 storms at Hospital ditch at Kamehameha Highway, and at Punamano ditch at Nudist

Camp Road (where the backflow into Punamano

marsh in November 1996 constituted an extreme

backwater effect). A probable marine backwater

effect was imposed at the ocean outlet ditch during

the November 1996 storm through a combination

of high spring tides and wave setup from large surf.

Whether this backwater effect propagated

upstream in the ditches to affect inland sites could

not be determined conclusively. A sand plug may

have built up in the ocean outlet channel before the

November 1996 storm, but if so, it probably

washed out prior to, or early in the storm, and was

not present at the time of peak stage at inland sites.

A season-long buildup of the sand plug in late 1997

was inferred from rising water levels in the outlet

ditch. Seawater flows up the outlet channel or over

the sand berm and into the outer ditch system on

most high tides, and particularly during spring high

tides.

Ponds and ditches of the Refuge and surrounding lowlands have mud- and clay-lined bottoms

that form an effective confining unit and inhibit

interaction with an underlying shallow limestone

aquifer. At Kii Unit, pond levels are higher than

adjacent ditch levels and underlying ground-water

levels, establishing lateral and downward head gradients that could foster seepage losses from the

ponds. Regional ground-water discharge from the

Koolau aquifer to the coastal-plain sediments is

mostly diffuse, but is concentrated where ridges of

Koolau Basalt plunge beneath coastal-plain sediments near Punamano Unit and at the head of Hospital ditch. Kii ditch gains brackish ground water

downstream of Kamehameha Highway. Wastewater disposal from the sewage treatment plant

adjoining Kii Unit poses little or no threat to Refuge habitat. Disposal is at six injection wells

located 0.45 mi away at Kahuku, and the wells

inject into confined limestone aquifers that do not

extend to Kii Unit.

The natural freshwater supply to Punamano

Unit is adequate for maintaining the wildlife habitat, judging from stable pond levels and low salinities there. A monthly water budget for Punamano

showed an apparent annual deficit in measurable

flows in 1997, requiring unmeasured ground-water

gains equalling 51 inches of water. The freshwater

supply to Kii Unit is inadequate according to Refuge managers, because there is not enough water to

manipulate levels adequately in the ponds during

most of the year, and particularly during the driest

months. This is confirmed by monthly deficits in

the water budget for the Kii ponds during summer

months. However, the Kii budget showed an

annual surplus in measurable flows for 1997 equalling 24 inches of water. Unmeasured losses are

required to explain the apparent annual surplus,

such as discharge to the ditches through pond

water-control structures and downward and/or lateral ground-water seepage. The apparent surplus at

Kii is strictly hydrologic and is not a surplus in a

management sense; it cannot be stored or used to

supply the Refuge, but instead reflects losses from

the system that render this amount of water

unavailable for use. The budget year, 1997, was

drier than normal (24 percent below long-term

mean rainfall) and so the measured potential evaporation for 1997 was probably higher than the longterm mean.

Few metals or organic compounds of potential

concern were detected in pond and ditch waters and

in pond-bottom sediments. Detected pesticides

were at trace levels or just above minimum reporting limits. Exceptions that exceeded quality guidelines for freshwater sediment were copper and zinc

in sediment from Kii ponds C and D, and copper in

sediment from Punamano north pond. Therefore,

urban and agricultural runoff probably have contributed little in the way of harmful metals or

organic compounds to the Refuge, although the

potential for such contribution remains from periodic flooding of the ponds by ditch stormflows.

Salinity was low throughout most Refuge waters,

qualifying as fresh to slightly brackish and suitable
Introduction 3

for the environmental needs of Refuge fauna.

Higher salinities have been observed in ditches

during past periods of sugarcane cultivation and

saltwater aquaculture, however. Resumption of

saltwater aquaculture could raise ditch salinities if

saltwater effluents are disposed directly into the

ditches, as they were in the past.

INTRODUCTION

The James Campbell National Wildlife Refuge

occupies two lowland marsh and pond complexes, the

Punamano and Kii Units, on the northern coastal plain

of Oahu near the town of Kahuku (fig. 1). The Refuge

is managed by the U.S. Fish and Wildlife Service

(USFWS) primarily to provide habitat for four native

endangered species of Hawaiian waterbirds: Hawaiian

coot (Fulica alai), Hawaiian duck (Anas wyvilliana),

Hawaiian stilt (Mimantopus mexicanus knudseni), and

Hawaiian moorhen (Gallinula chloropus sandvicensis).

Management for these endangered waterbirds also provides habitat for other migratory waterbirds. To address

concerns about the adequacy of existing water sources

and the quality of water, and to learn more about the

hydrology of a wetland in a tropical island environment,

the USFWS entered into a cooperative agreement with

the U.S. Geological Survey (USGS) in 1994 to conduct

a hydrologic study of the Refuge. This report summarizes the results of this study.

Ponds within the Refuge are partly covered by

marsh plants such as bulrush and cattails that provide

nesting habitat, and the muddy pond bottoms contain

invertebrates on which waterfowl feed. The Punamano

Unit is a marsh and pond complex (fig. 2) that is fed by

natural water sources: rainfall, runoff, at least two

known springs, and perhaps by diffuse ground-water

seepage. Water from the marsh drains freely into

Punamano ditch and then flows east to the ditch terminus at Kii Unit. The fair-weather water level in

Punamano north pond is about 2.5 ft above sea level,

and the altitude of the pond bottom varies from about 0

to 2 ft above sea level. To the west lies Punahoolapa

marsh (figs. 1 and 2), a former natural marsh that has

been landscaped into a golf course with open-water

ponds as water hazards. Marconi Road separates

Punamano marsh from Punahoolapa marsh, except during extreme floods that inundate the road.

At Kii Unit (fig. 3) the former natural marsh was

landscaped into an assemblage of bermed ponds that

were used until 1971 for settling sugarcane wash water

from nearby Kahuku Mill. In 1976, USFWS established

the Kii Unit of the Refuge, supplying the ponds with

water from adjacent ditches and from artesian wells.

Earthen berms or levees of compact silty clay separate

the ponds and ditches from each other. Berm tops have

a nominal altitude of 6 ft above sea level, and in fair

weather, pond water levels are maintained at about 3 to

4.5 ft and adjacent ditch water levels are about 2 ft.

Water depth in the ponds is about 1 to 2 ft. The pond

bottoms lie about 2 to 4 ft above sea level and are underlain by several feet of soft, organic-rich mud. Water levels, berms, and pond bottoms for ponds A and E are

lower in altitude than those of the other ponds: water

levels typically are 1.5 to 3 ft, and the bottom of pond A

is at 0.7 ft.

To maintain desired water levels and water quality

in the Kii ponds, water from direct rainfall is supplemented by water from free-flowing artesian wells

directed through the ponds by a system of pipelines and

water-control structures. Ponds G, F, C, and B are fed

directly by pipeline, whereas control structures feed

pond D from pond F, and pond A from pond B. Pond E

is fed through control structures connected to adjacent

ditches, and not by the artesian well water. One or two

of the Kii ponds are drained annually to burn and

remove excess vegetation during the non-nesting season from summer into early fall.

A regional system of shallow ditches (fig. 1) drains

the Kahuku coastal plain (essentially, the area seaward

of Kamehameha Highway) and conveys the flow of

several streams that empty out from the adjacent volcanic uplands. Several of the ditches (Punamano, Kii,

Hospital, and Raboy) run through or around Kii Unit

(fig. 3), being separated from the Kii ponds by earthen

berms or levees. These ditches terminate in an outer

ditch (Kii ocean outlet) where water flows to the ocean

via a channel that was blasted through a raised limestone shelf that borders the coast.

Within Kii Unit, Punamano, Kii, and Hospital

ditches join in confluence behind an earthen berm separating the inner ditch system from the outer ditch (fig.

3). From this confluence, water in the inner ditch flows

to the outer ditch through a culvert and one-way tidal

duckbill valve if the inner ditch level is higher than the

outer ditch; is forced out by a high-capacity, 40-horse-
Ko olau drainag e

divide

Koolau rift-zone margin

PACIFIC

OCEAN

Koolau rift-zone margin

Koolau

rift-zone

margin

Koolau rift-zone margin

Punamano Unit

Bakahan ditch

MCE ditch

Punamano ditch

Punahoolapa marsh

Kii ocean outlet ditch

Raboy ditch

Hospital ditch

Kii ditch

Ko olau

drain

a

g

e

divide

Kii Unit

Kahuku Point

Kuilima Point

Laie

Point

Rain gage

Figure 1. James Campbell National Wildlife Refuge and surrounding area near the town of Kahuku in northern Oahu, Hawaii.

22°

20°

160° 158° 156°

PACIFIC OCEAN

Kauai

Niihau

Oahu

Maui

Molokai

Lanai

Kahoolawe

Hawaii

HAWAII

OAHU Pacific

Ocean

Area

of map

Kahuku

Kamehameha

Highway

Kahuku

157°56'

21°39'

21°42'

158°

Base from U.S. Geological Survey digital elevation and digital line graph maps, 

Kahuku quadrangle, 1:24,000

    



EXPLANATION

ALLUVIAL FAN--Shown here in the vicinity 

only of the Punamano and Kii Units of the 

James Campbell National Wildlife 

Refuge





JAMES CAMPBELL NATIONAL WILDLIFE 

REFUGE--Punamano and Kii Units

















0

0

0.5 1 MILE

0.5 1 KILOMETER

4 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii
157°59' 157°58'23"

21°42'

21°41'45"

Figure 2. Punamano Unit of James Campbell National Wildlife Refuge, Oahu, Hawaii.

pond

Marconi Road

Kamehameha Highway

Nudist Camp Road

North

pond

Punahoolapa

marsh

South

pond

(small)

South

pond

(large)

West ponds

(large) (medium)

(small)

Limit of marshy

wetland

Spring 

pond

Plum Tree

Spring r

Punamano

Spring r

Punamano ditch

Ditch

OAHU Pacific

Ocean Area

of map

0 500 1,000 FEET

0 100 200 METERS

FLOW DIRECTION IN DITCH OR POND

EXPLANATION

? ?

?

?

?

? ?

?

Base from U.S. Geological Survey digital line graph maps, 

Kahuku quadrangle, 1:24,000

Introduction 5
Sand plug

Ditch

pond

Ra boy

ditch

Outer ditch system

Blind ditch

Outlet pump

Outlet duckbill

Outer flood-relief swale

Inner ditch terminus

Inner flood-relief swale

A

C B

D

G

F-seaward

F-inland

E-inland

E-seaward

Raboy ditch

Ocean outlet channel

Refuge fence

Road

Punamano

Hospital ditch

Hospital ditch

Kii

artesian

wells

Kii

ditch

Visitor

kiosk

Kahuku

sewage

treatment

plant

PACIFIC

OCEAN

Figure 3. Kii Unit of James Campbell National Wildlife Refuge, Oahu, Hawaii.

21°41'50"

157°57'30" 157°57'20"

21°41'35"

OAHU Pacific

Ocean Area

of map

0 500 1,000 FEET

0 100 200 METERS

WATER-CONTROL STRUCTURE CONTROLLING FLOW TO AND FROM POND

OPEN CULVERT

CULVERT WITH DUCKBILL VALVE

PIPELINE FROM KII ARTESIAN WELL TO PONDS

FLOW DIRECTION IN DITCH OR POND

ADDITIONAL FLOW OUTLETS AT FLOOD STAGE

EXPLANATION

Base from U.S. Geological Survey digital line graph maps, 

Kahuku quadrangle, 1:24,000

6 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii
Introduction 7

power pump that is triggered when the inner ditch level

rises above 1.8 ft; or flows freely to the outer ditch at

high flood stage, over a low, flood-relief swale in the

berm at an altitude of 3.5 ft. Most fair-weather flow and

moderate stormflows exit the coastal plain through the

Kii ocean outlet. During severe floods that inundate

much of the coastal plain, substantial volumes of water

may also discharge to the sea through MCE (Marine

Culture Enterprises) ditch and the Bakahan ditch, which

was re-opened in 1995.

Operation and wildlife habitability of the Refuge

depend on its internal hydrology as well as the surrounding environment (fig. 4). Within the Refuge,

inflows of freshwater from rainfall, streams, wells, and

ground-water sources must be large enough to offset

evaporative concentration and keep salinity in the ponds

and marshes sufficiently low. Punamano marsh apparently receives considerable ground-water inflow from

surficial sediments and from the Koolau aquifer,

whereas ponds at Kii probably do not receive appreciable ground-water inflows and so must be supplemented

with well water.

Potential water-quality problems are from suspended sediment and chemical residues in agricultural

and urban runoff, from saline aquaculture effluents, and

from saline water from the ocean (by tidal incursion

upstream through the ditch system). Water quality in the

Refuge also may be affected by interaction with underlying ground water, which in the surrounding coastal

plain is subject to saltwater intrusion, subsurface disposal of domestic wastewater and saline aquaculture

effluents, and potentially by chemical residues from fertilizers and pesticides used in the surrounding area.

Purpose and Scope

The purpose of this report is to describe the hydrology and water and sediment quality of the James Campbell National Wildlife Refuge and the hydrologic

interaction of the Refuge with the surrounding Kahuku

coastal plain. To meet this objective the following steps

were undertaken:

1. Streamflow and water levels in ditches entering

and leaving the Refuge were analyzed to define

the major sources of surface-water inflow, to

determine the role that the ocean plays in

controlling ditch water levels and outflow

rates, and to identify hydraulic factors

affecting flooding within and immediately

surrounding the Refuge.

2. Hydrogeology, ground-water levels, and salinity

surveys were evaluated to qualitatively

document ground-water and surface-water

interactions in the area of the Refuge. This

evaluation forms a basis for describing how

water bodies in the Refuge interact with

surrounding ditches, ground-water bodies, and

the ocean, and for describing potential effects

of subsurface disposal of treated wastewater

from the Kahuku sewage treatment plant on

the Refuge.

3. Transfers of water in and out of the Punamano

and Kii Units of the Refuge were summarized

in the form of water budgets to quantify the

adequacy of the current freshwater supply,

particularly during the dry season.

4. Surveys of water quality were done in principal

Refuge water sources and selected ponds to

evaluate water quality within the Refuge and to

provide a baseline description of current waterquality conditions from which potential future

changes could be measured. Bottom sediments

from selected ponds also were analyzed to

determine whether chemical compounds that

could affect wildlife have accumulated.

The scope of the work included installation and

operation of recording and non-recording gaging stations to measure streamflow and water levels in ditches,

ponds, and piezometers, operation of meteorologic stations to measure precipitation and data required to estimate evapotranspiration, surveys to convert all

recorded water levels to a common datum, and synoptic

salinity surveys and sampling of water and sediment

within the Refuge and its principal sources of inflow.

Also used in this study were previous geologic studies

of the Kahuku area (including documented well logs) as

well as water level, precipitation, and well discharge

rates provided by the USFWS. Although several gaging

stations were established for this study as early as 1995,

data analysis focused on the 16-month period from

November 1996 through February 1998, when concurrent data were available from most or all of the principal

gaging stations. This period included several moderate

storms and a full calendar year over which water budgets were computed.
 



 



Evapotranspiration

Streamflow in

Punamano

Spring

Rainfall

+2.5 ft

+12 ft

+150 ft

-480 ft

GEOLOGY

Alluvium, mainly silty clay

Pond bottom mud

Limestone

Lithified calcareous dunes

Beach rubble or coarse alluvium

Lagoon mud

Koolau Basalt

EXPLANATION

HYDROLOGY

Freshwater

Brackish water

Saltwater

DIRECTION OF GROUND-WATER FLO

OTHER HYDROLOGIC FLUXES (la

DIRECTION OF GROUND-WATER FLO

(small magnitude)

PUNAMANO SPRING AND OTHER SP

POND WATER LEVEL OR GROUND-W

TABLE IN AQUIFER



Figure 4. Simplified geology and modes of ground-water/ surface-water interaction at Punamano and Kii Units, James Campbell N

Oahu, Hawaii.

SOUTH

Punamano Unit







8 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii
Introduction 9

     

 

    



Berm

Ditch

Berm

Evapotranspiration

Rainfall

4 ft 1.3 ft 1.3 ft

1.8 ft

3–4 ft 1–3 ft

Seaward pond

Artesian well flow

Potentiometric head

in Koolau Basalt

12 ft

GEOLOGY

Alluvium, mainly silty clayPond- or ditch-bottom mudLimestoneKoolau Basalt

EXPLANATION

HYDROLOGY

FreshwaterBrakish waterSaltwater

DIRECTION OF GROUND-WATER FLOW AND 

OTHER HYDROLOGIC FLUXES (large magnitude)

DIRECTION OF GROUND-WATER FLOW

(small magnitude)

POND WATER LEVEL OR GROUND-WATER LEVEL

IN AQUIFER OR WELL

SOUTH



Kii Unit

NORTH

Figure 4. Simplified geology and modes of ground-water/ surface-water interaction at Punamano and Kii Units, James Campbell National Wildlife Refuge, Oahu, Hawaii--Continued.
10 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

Acknowledgments

Scientists and staff at the U.S. Fish and Wildlife

Service (USFWS) field office in Haleiwa, Hawaii, provided valuable assistance and guidance regarding the

history and operation of the Wildlife Refuge, and furnished data from their wells, ponds, and meteorology

station. Staff at USFWS headquarters in Portland, Oregon, supplied data from water-level recorders at the

Refuge ponds. The Estate of James Campbell granted

access to Estate lands outside the boundaries of the

Wildlife Refuge for reconnaissance surveys of the

greater coastal plain. Digital topographic maps of the

Kahuku area were furnished by the U.S. Army Corps of

Engineers, Pacific Ocean Division, at Fort Shafter,

Hawaii. The U.S. Army also granted access to their

training area in the Kahuku uplands for construction

and operation of a rain gage. The State of Hawaii

Department of Transportation issued a permit for a

stream-gaging station in a storm drain at Kahuku. Thomas Giambelluca and Michael Nullet, of the University

of Hawaii, operated a meteorologic station at Kii Unit

under contract.

DESCRIPTION OF THE STUDY AREA

Physiography

The Kahuku landscape (fig. 1) is formed by two

principal physiographic provinces: (1) the mountainous

Koolau Range in the interior, and (2) a coastal plain seaward of Kamehameha Highway. The Koolau Range is

the elongated eroded remnant of a shield volcano that

plunges beneath the coastal plain and extends north for

many miles beneath the sea. The northernmost terminus

of the Range forms the Kahuku uplands. Surficial lavas

of Koolau Basalt (Stearns and Vaksvik, 1935; Stearns,

1939) have been deeply weathered, leaving a mantle of

readily erodible red soil tens of feet thick over most of

the uplands.

The low-lying coastal plain separates the Kahuku

uplands from the sea by as much as 1.5 mi. The land surface is less than 10 ft above sea level throughout much

of the coastal plain, except along seaward dune ridges.

The coastal plain is underlain by marine sediments and

basaltic alluvium washed down from the uplands, and

by Koolau Basalt at depth. Streams have deposited alluvial fans where they empty out onto the coastal plain at

the mouths of their valleys. Two prominent alluvial fans

are aligned with Punamano and Kii marshes (fig. 1).

The fans are readily noticeable when driving along

Kamehameha Highway as broad rises at altitudes of 20

to 30 ft above sea level.

The Koolau Range is deeply dissected by streams

that have followed the consequent drainage pattern

established on the original domed surface of the Koolau

shield volcano. In the Kahuku area, this has resulted in

a divergent, radial drainage pattern of the main stream

courses, with tributaries branching off in a dendritic pattern. The divergent drainage pattern has generated triangular interfluves of relatively undissected terrain known

as flow-slope facets (Wentworth, 1951).

Streams of interest in this study are those that

empty onto the coastal plain near the Refuge. Drainage

boundaries for selected streams, and for the coastal lowlands surrounding the Refuge, are shown in figure 5,

and drainage areas are listed in table 1. These drainage

areas cannot be considered definitive. In particular,

drainage areas on the coastal plain are ambiguous

because variations in topography are subtle. Drainage

areas delineated on the coastal plain may merge into

larger standing lakes during extreme floods (State of

Hawaii Department of Land and Natural Resources,

1971).

Streams in the Kahuku area are short, with steep

gradients and small drainage areas. In the uplands, steep

terrain and stream gradients cause surface water to run

off rapidly, and permeable upland soils permit rapid

infiltration of rainfall to the underlying Koolau aquifer.

As a result, streamflow near the Refuge is characteristically flashy, with high flood peaks and little base flow.

Streamflow is perennial at high altitudes where rainfall

is persistent and streams intercept dike-impounded

ground water, and at altitudes of 10 ft or less, where

streambeds cut into the basal water table in the Koolau

aquifer or in sediments.

The drainage area for the Punamano Unit is 0.42

mi2

, which includes 0.34 mi2 on the coastal plain and

0.08 mi2 of unnamed upland watershed just inland of

Kamehameha Highway. Hoolapa Gulch drains a small

watershed to the west of the Punamano Unit into

Punahoolapa marsh, from which no apparent outlet to

the sea can be identified on topographic maps. Marconi

Road separates Punahoolapa marsh from Punamano

marsh and likely forms a drainage divide between the

two under most runoff conditions. However,
Kamehameha

High way

Ko olau drainag e

divide

Koolau rift-zone margin

PACIFIC

OCEAN

Koolau rift-zone margin

Koolau

rift-zone

margin

Koolau rift-zone margin

Punamano

Unit

Punamano

ditch

Ko olau

drain

a

g

e

divide

Kii Unit

Kii ditch

Hospital ditch

EXPLANATION

KOOLAU BASALT

VALLEY AND COASTAL PLAIN 

 SEDIMENTS

DRAINAGE BASIN BOUNDARY

 OF STREAM, GULCH, OR DITCH

VOLCANIC FEEDER DIKE

DRAINAGE BASIN 

 NUMBER--see table 1

Keaaulu

Gulch

Keaaulu

Gulch

Malaekahana

Stream

Ohia Ai

Gulch

Kalaeokahipa

Gulch

Hoolapa Gulch

Oio

Gulch

Rain gage

(station 9)

Figure 5. Streams and selected surface drainage boundaries in the vicinity of James Campbell National Wildlife Refuge, 

Oahu, Hawaii.

Kahuku

Base from U.S. Geological Survey digital line graph maps, 

Kahuku quadrangle, 1:24,000

Laie

Point

Kahuku Point

OAHU Pacific

Ocean

Area

of map

157°56'

21°39'

21°42'

158°

0

0

0.5 1 MILE

0.5 1 KILOMETER

1a

1b

8

6

2

3

3

5 4

7

Description of the Study Area 11
12 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

Punahoolapa marsh may drain eastward to Punamano

marsh and ditch during extreme floods that overtop

Marconi Road.

Several streams drain to the Kii Unit of the Refuge.

Ohia Ai Gulch has a drainage area of 2.48 mi2

 that

extends into the Koolau rift zone, all the way to the crest

of the Koolau range (fig. 5). Seaward of Kamehameha

Highway, Ohia Ai Gulch is known as Kii ditch, which

joins with Punamano ditch prior to entering the Kii Unit

at its west boundary. Kalaeokahipa Gulch drains an area

of 1.04 mi2

 inland of Kamehameha Highway into

Punamano ditch, which flows east to the Kii Unit. Also

draining to Kii Unit is Hospital ditch, a 0.27 mi2

 watershed that is bordered by Kahuku Hospital, and runoff

from a residential subdivision that drains to Kahuku

storm drain (drainage area 0.08 mi2

). The next valley to

the east, Keaaulu Gulch, does not drain to the coastal

lowlands that encompass the Refuge: its stream follows

a path through low hills behind a residential subdivision, joins Malaekahana Stream just inland of Kamehameha Highway, and discharges directly to the ocean

south of Kahuku.

Climate

The Kahuku area is subject to a subtropical climate

characterized by mild temperature, moderate humidity,

prevailing northeasterly trade winds, and extreme variation in rainfall over short distances. Climate varies spatially with altitude and in relation to prevailing and local

winds. Mean annual temperature is about 76°F in the

coastal lowlands of Oahu, decreasing to less than 70°F

in the mountainous uplands (Blumenstock and Price,

1967).

Rainfall and cloud cover increase with altitude and

in the inland direction, following an orographic pattern

established as moist oceanic air is forced up and over

the Koolau Range by persistent northeasterly trade

winds or sporadic southwesterly winds that accompany

winter low-pressure systems. Median annual rainfall

1

 Considered here as not contributing runoff to the interior coastal plain or the Refuge, owing to high infiltration capacity and proximity to the

coast

Table 1. Drainage areas in the vicinity of the James Campbell National Wildlife Refuge, Oahu, Hawaii

[Areas were determined by geographic information system (GIS), using digital topographic maps provided by the U.S. Army Corps of Engineers,

USGS digital line graphs (DLG's) for the Kahuku quadrangle, and a digital version of the geologic map of Oahu (Stearns, 1939); ft2

, square feet;

mi2

, square miles]

Drainage area

Drainage area

number

(fig. 5)

Area

(acre) (mi2)

Drainage areas for stream-gaging stations

Station 1 Punamano ditch 1 268 0.419

Station 2 Kalaeokahipa Gulch 2 663 1.036

Station 3 Kii ditch/Ohi Ai Gulch 3 1,585 2.476

Station 4 Kahuku storm drain 4 51 0.080

Station 5 Hospital ditch 5 173 0.270

Other areas of interest

Coastal plain minus sand and Punamano 6 1,081 1.689

Sand (dunes and beach)1 7 172 0.269

Nudist Camp Road ditch inland 8 14 0.022

Punamano (Station 1 seaward) 1a 217 0.339

Punamano inland (Station 1 inland) 1b 51 0.080

Selected totals

Uplands (inland of highway) 2,537 3.964

Coastal plain (seaward of highway) 1,470 2.297

Coastal plain minus sand 1,298 2.028

Total area 4,007 6.261

Total minus sand 3,835 5.992
Data-Collection Program 13

increases from about 39 inches at the town of Kahuku,

to about 150 inches at the headwaters of Ohia Ai Gulch,

to over 300 inches near the crest of the Koolau Range

farther south (State of Hawaii Department of Land and

Natural Resources, 1982; Giambelluca and others,

1986). Mean annual rainfall over the open ocean near

Oahu has been estimated to be about 25 inches (Blumenstock and Price, 1967).

Rainfall on Oahu is seasonal, with wetter winter

months from October through April, and drier summer

months from May through September. The uplands

receive a steady contribution of tradewind rainfall

throughout the year, supplemented by intense, episodic

rains from winter cold fronts, convective disturbances

associated with upper-atmosphere low-pressure systems, and occasional hurricanes. The coastal plain

receives a lesser proportion of total rainfall as tradewind

rain and a much greater proportion as episodic, winter

rain.

Evaporation varies inversely with cloud cover and

rainfall, and is greatest on the sunny coastal plain and

least in the rainy uplands. On the Kahuku coastal plain,

Ekern and Chang (1985) report annual pan evaporation

to be 82.2 in. for the period 1960–65.

Ekern and Chang (1985) also provided an empirical fitting equation for Oahu that can be used to estimate

annual pan evaporation (Evap) from median annual

rainfall (with both in inches):

log Evap (in/yr) = 1.99−0.003 Rain (in/yr) (1)

Using this equation, annual pan evaporation is estimated to be about 35 in. at the headwaters of Ohia Ai

Gulch.

Land Use

The Kahuku area is primarily rural. Land use

includes forest, agriculture, and aquaculture, with light

suburban development clustered in the town of Kahuku.

Two golf courses are located on the Kahuku coastal

plain: one occupies high dune fields just east of the

town of Kahuku and the other one adjoins an extensive

resort at the west end of the coastal plain near Kuilima

Point, occupying the former Punahoolapa marsh.

Gently sloping areas in the lowlands, and in the

uplands to altitudes of about 200 ft, were cultivated for

sugarcane by Kahuku Plantation Co. from 1890 through

1971. By 1940, ground-water withdrawal for sugarcane

irrigation was averaging about 30 Mgal/d (million gallons per day; Takasaki and Valenciano, 1969). After the

end of sugar cultivation, these lands were put to use for

ranching, diversified-crop farming, and aquaculture.

Residential development is more widespread now than

in plantation times, but the area is still comparatively

rural.

Aquaculture flourished on the coastal plain during

the 1970's to mid-1990's and included a mix of both

freshwater and saltwater products such as prawns,

shrimp, oysters, and fish stock. Most of the aquaculture

companies eventually halted production. One of the

largest of the operations ceased production in 1994,

leaving extensive aquaculture ponds lying dormant on

the broad alluvial fan between Nudist Camp Road and

Kii Unit and between Kamehameha Highway and

Punamano ditch. A tract of ponds immediately southwest of Kii Unit had been under freshwater aquaculture,

whereas the remainder of the area had been under saltwater aquaculture (fig. 6).

Inland, the rugged, mountainous terrain is mostly

forested conservation land, typically designated as

watershed preserves. The U.S. Army uses parts of the

Kahuku uplands as a training area.

DATA-COLLECTION PROGRAM

Field data were collected to furnish estimates of

relevant surface-water, ground-water, and atmosphericwater fluxes, and to characterize the quality of water in

ponds and water sources within the Refuge. The datacollection program included a fixed network of 39

surface-water, ground-water, meteorology, and waterand sediment-chemistry stations, as well as a salinity/seepage survey that included measurements at 107

sites.

The stations that make up the fixed data-collection

network are listed in tables 2 and 3, and are shown in

figures 6 through 9 (the location of upland rain gage station 9 is shown in fig. 5). Concurrent records were

obtained from primary surface-water and meteorology

stations 1 through 11, 21, 35, and 36, and from groundwater station 6 for a period of 1 year, from January

through December 1997. Several of these stations were

in operation before or after 1997 and provided auxiliary

data for significant events such as the severe storm of

November 14, 1996. Records were obtained at ground-
14 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

Table 2. Fixed data-collection stations and benchmarks included in the hydrologic and meteorologic data network at James

Campbell National Wildlife Refuge, Oahu, Hawaii

[USFWS, U.S. Fish and Wildlife Service; USGS, U.S. Geological Survey; USCGS, U.S. Coast and Geodetic Survey; continuous recorders were operated at

stations marked “Y”; precise altitudes were surveyed to most stations (except 9 and 35–37) and are available in files of the U.S. Geological Survey, Honolulu,

Hawaii; datum for altitudes is mean sea level; ft, feet; --, not applicable; stations are shown on figures 6–8]

Station

number

Station

name

Station

type Location or description Type of measurement; remarks Recorder Source ofdata

Primary surface-water and meteorology stations

1 Sta 1 Flow meter Punamano ditch duckbill Ditch level, discharge, chemistry Y USGS

2 Sta 2 Stage gage Kalaeokahipa Gulch Stream level, discharge Y USGS

3 Sta 3 Stage gage Kii ditch/Ohia Ai Gulch Ditch level, discharge, chemistry Y USGS

4 Sta 4 Flow meter Kahuku storm drain Ditch level, discharge, chemistry Y USGS

5 Sta 5 Stage gage Hospital ditch / Mill ditch Ditch level only Y USGS

7 Sta 7 Flow meter Kii outlet duckbill/inner ditch Ditch level, discharge Y USGS

8 Sta 8 Stage gage Kii ocean outlet/outer ditch Ditch level only Y USGS

9 Sta 9 Rain gage Upland rain gage Rain Y USGS

10 Sta 10 Met station University of Hawaii meteorology

station

Rain, evaporation, temperature, windspeed,

humidity, solar radiation, soil heat flux

Y UH

11 Sta 11 Pump timer Kii outlet pump Ditch level, pump on/off time, barometric

pressure

Y USGS

21 Staff B Staff gage Pond B at gate to pond A Pond level Y USFWS, USGS

35 USFWS Met Met station USFWS meteorology station Rain, temperature, humidity, wind speed and

direction, barometric pressure

Y USFWS

36 Puna pond Staff gage Punamano north pond Pond level, chemistry Y USFWS

Ground-water stations

6 Sta 6 Well meter Kii artesian wells; flow meters Ground-water withdrawal, chemistry -- USFWS

12 Sta 12 Piezometer Kii Pond D next to Punamano ditch Ground-water and pond level, chemistry Y USGS

13 Sta 13 Piezometer Punamano ditch next to pond D Ground-water and ditch level Y USGS

14 Sta 14 Piezometer Kii Pond D inland Ground-water and pond level -- USGS

15 Sta 15 Piezometer Kii Pond C next to Hospital ditch Ground-water and pond level Y USGS

16 Sta 16 Piezometer Hospital ditch next to pond C Ground-water and ditch level -- USGS

17 Sta 17 Piezometer Pond A next to outer ditch Ground-water and pond level Y USGS

18 Sta 18 Piezometer Pond F near sewage treatment plant Ground-water and pond level -- USGS

19 STPwell Monitoring well Kahuku sewage treatment plant Ground-water level -- USGS

Supplemental surface-water stations and miscellaneous sites

20 Staff A Staff gage Pond A at gate to outer ditch Pond level -- USFWS, USGS

22 Staff C Staff gage Pond C at gate to Hospital ditch Pond level -- USFWS, USGS

23 Staff Ck Staff gage Pond C at kiosk gate Pond level -- USFWS, USGS

24 Staff D Staff gage Pond D at gate to Punamano ditch Pond level -- USFWS, USGS

25 Gate E-in Gate Pond E gate to inner (Punamano) ditch Pond level -- USGS

26 Gate E-out Gate Pond E gate to outer ditch Pond level -- USGS

27 Staff F Staff gage Pond F at gate to pond G Pond level -- USFWS, USGS

28 Staff G Staff gage Pond G at gate to Punamano ditch Pond level -- USFWS, USGS

29 Gate A-out Gate Pond A gate to outer ditch east arm Pond level -- USGS

30 Gate B-H Gate Pond B gate to Hospital ditch Pond level -- USGS

31 Gate F-C Gate Pond F gate to pond C near kiosk Pond level -- USGS

32 Gate F-D Gate Pond F gate to pond D Pond level -- USGS

33 Swale-in Relief swale Inner swale Hospital to Punamano ditch Ditch level; altitude 3.43 ft -- USGS

34 Swale-out Relief swale Outer swale Punamano to outer ditch Ditch level; altitude 3.53 ft -- USGS

37 Puna spring Spring Punamano Spring Chemistry -- USGS

44 Pond C chem Pond Kii pond C next to Punamano ditch Chemistry -- USGS

45 Hosp chem Ditch Hospital ditch at Kii Refuge fence Chemistry -- USGS

Benchmarks

38 BM-kiosk Benchmark Kii Unit visitor kiosk USFWS benchmark; altitude 6.00 ft -- USGS

39 BM-A Benchmark Near Kii pond A staff gage USFWS benchmark; altitude 5.20 ft -- USGS

40 BM-B Benchmark Kii pond B staff gage USFWS benchmark; altitude 6.06 ft -- USGS

41 BM-C Benchmark Kii pond C staff gage USFWS benchmark; altitude 6.86 ft -- USGS

42 Windmill Benchmark Kii, at Punamano ditch and kiosk berm Temporary benchmark; altitude 5.54 ft -- USGS

43 BM-23 Benchmark Highway bridge at Hoolapa Gulch USCGS benchmark; altitude 22.66 ft -- USCGS
Data-Collection Program 15

water stations 12 through 18 for the 4 month period

from September 1997 through December 1997. The

majority of the remaining stations were not recording

stations and were read manually throughout the study

period.

Precise altitudes were surveyed to all water-level

measuring points so that water levels could be

expressed as absolute altitudes relative to the common

datum of mean sea level. Altitude surveys were run

from a single, U.S. Coast and Geodetic Survey benchmark on the Hoolapa Gulch bridge abutment at Kamehameha Highway (station 43) to ensure consistency of

results.

Surface-Water Stations

The primary network of surface-water stations for

this study were stations 1 through 5, 7, 8, and 11, most

of which were equipped with continuous data recorders

operated by the USGS, and pond-stage gages at stations

21 and 36, operated by USFWS (fig. 6). Supplemental

stations 20 and 22 through 34 included staff gages and

water-control structures within the various ponds, and

two flood-relief swales in earthen berms that separate

principal ditches at Kii Unit (fig. 7).

Stations 2, 3, 5, and 8 were stream-stage gages. At

this type of gage, a low check dam with a v-notch weir

across the stream acts as a stage-discharge control. An

upstream stilling well has intakes, hydraulically connected to the stream, that ensure water levels in the well

are the same as those in the stream. A sensor continuously measures water levels in the protected environment inside the stilling well. Electronic data recorders

store the output from the water-level sensor, typically at

10-minute intervals.

A rating curve is developed for the station to convert the records of stream stage to stream discharge.

Once a sufficient number of discharge measurements

are made, a rating curve can be plotted relating stream

stage to discharge. The discharge measurements must

be made over sufficiently broad ranges of stage and discharge in order for a valid rating curve to be developed.

At station 2 on Kalaeokahipa Gulch, the entire

stream gage was washed away by the flood of November 14, 1996 and no record was available until the station was rebuilt on December 18, 1996. The lack of

continuous submergence of the water-level sensor during periods of no flow and frequent recorder malfunctions limited the periods when discharge was

quantifiable at station 2 to brief periods during storms.

At station 5 on Hospital ditch, discharge was not quantified because the number of storms measured was

insufficient to develop an accurate rating curve. Station

8 was designed as a stage-only gage, because ocean

tides cause frequent reversals of flow direction in the

Kii ocean outlet making it impossible to develop a

unique rating curve.

Stations 1, 4, and 7 were located in cylindrical culverts or storm drains in which doppler-ultrasonic flow

meters were installed. Station 4 was at a storm drain that

delivers runoff into Hospital ditch from a nearby residential neighborhood in the town of Kahuku. Stations 1

and 7 measured channel ditchflows beneath roads at

locations where the culverts are outfitted with one-way,

tidal-control, "duckbill" valves on their downstream

ends. The valves are designed to help prevent backflow

and facilitate downstream flow through the culvert. The

duckbill valve at station 7 was installed to prevent

incursion of saline water into the inner ditch system that

borders the freshwater ponds at Kii Unit. Similarly, the

duckbill valve at station 1 was installed to prevent backflow of potentially brackish-to-saline water from the

lower reaches of Punamano ditch up into Punamano

Unit and environs.

The doppler-ultrasonic flow meters at stations 1, 4,

and 7 used multiple sensors affixed to the inside of the

culvert. One sensor was a bubbler tube connected to a

pressure transducer that measured water level. Water

level was converted into a wetted area on the basis of

known culvert geometry, which at these stations was

cylindrical. Another sensor emitted an ultrasonic pulse

and sensed the timing of the return pulse using the doppler principle to compute the average velocity of water

in the culvert. The meter then multiplied the average

velocity by the wetted area of the culvert to compute

flow at 10-minute intervals. The doppler flow meters

were capable of sensing reversals of flow in the culverts

and could measure flow rates in both the upstream and

downstream directions.

Station 11 was equipped with a continuous

recorder that measured barometric pressure, inner

(Punamano) ditch level, and pump on and off times for

the Kii outlet pump. The 40 horsepower pump at station

11 was rated at a nominal pumping rate of 12,000

gal/min. By recording the pump on and off times,
Figure 6. Primary network of surface-water and meteorologic stations, James Campbell National Wildlife Refuge, Oahu, Hawaii (al

rain gage station 9 shown on figure 5).

EXPLANATION

Ohia Ai Gulch

Punamano Unit

Kii Unit

Limit of

marshy wetland

Punahoolapa

marsh

Ditch

Punamano

Kii Ditch

MCE Ditch

Nudist Camp Road

Saltwater

aquaculture

ponds

Freshwater

aquaculture

ponds

Marconi Road

K al aeoka

pa hi

ulc G

h

Kamehameha Highway

hcti Dl ati pso H

21°42'12"

21°41'35"

157°58'10" 157°57'20"

b

b

b

b

b

b

b

b

b

b

b

b

b

36-S

43-BM

1-SD

2-SD

b 2-SD

35-M

7-SD

11-SDB

21-

3-SD

5-S

4-SD

10-M

8-S

DATA-COLLECTION STATION

AND NUMBER, LETTERS 

INDICATE TYPE OF DATA 

COLLECTED OR BENCHMARK:

S, Surface-water level (stage)

D, Surface-water discharge

M, Meteorology (multi-variable)

B, Barometric pressure

BM, Benchmark

0 500 1,000 FEE

0 100 200 METERS

Base from U.S. Geological Survey digital line graph maps, 

Kahuku quadrangle, 1:24,000

16 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii
Sand plug

Ditch

pond

Ra boy

ditch

Raboy ditch

Ocean outlet channel

Refuge fence

Road

Punamano

Hospital ditch

Figure 7. Supplemental surface-water stations and benchmarks at the Kii Unit, James Campbell National Wildlife Refuge, 

Oahu, Hawaii.

21°41'50"

157°57'30" 157°57'20"

21°41'35"

A

C B

D

G

F-seaward

F-inland

E-inland

E-seaward

Hospital ditch

Kii

ditch

b

b b

b b

b

b

b

b

b

b

b

bb

b b

b

b

25-S

31-S

38-BM

23-S

27-S

30-S

32-S

28-S

b

28-S

34-S

29-S

39-BM

25-S

22-S

41-BM

26-S

24-S 42-BM

20-S 33-S

40-BM

EXPLANATION

SURFACE-WATER STATION

AND NUMBER, LETTER 

INDICATES TYPE OF DATA 

COLLECTED OR BENCHMARK:

S, surface-water level

BM, benchmark

PACIFIC

OCEAN

OAHU Pacific

Ocean Area

of map

0 500 1,000 FEET

0 100 200 METERS

Base from U.S. Geological Survey digital line graph maps, 

Kahuku quadrangle, 1:24,000

Data-Collection Program 17
18 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

pumping duration can be computed. Duration was then

multiplied by the nominal pumping rate to estimate discharge from the inner ditch system through the pump.

About 6 weeks of record were lost to recorder malfunction in 1997. However the pumpage record at station 11

was reconstructed using the water-level data at nearby

station 7 to estimate pump on and off times. The pump

at station 11 is operated for two primary reasons: to

assist the nearby outlet culvert, at station 7, in transferring water out of the inner ditch system and into the

outer ditch and subsequently into the ocean (this is particularly important during stormflows when the capacity of the outlet culvert is frequently exceeded); and to

transfer water out of the inner ditch system when water

will not flow out unassisted, for example during high

tides, when the water level in the outer ditch is higher

than that in the inner ditch and the station 7 duckbill

valve remains closed.

Intermittent, manual readings of water levels were

made at stations 20 and 22 through 34 to provide synoptic surveys of pond and ditch levels throughout Kii Unit

(fig. 7). Water levels were measured at graduated staff

gages maintained by USFWS in each of the Kii ponds,

at water-control structures, and at flood-relief swales in

earthen berms. Swale-in (station 33) is the "inner"

flood-relief swale separating Hospital ditch from

Punamano ditch near the outlet pump. A culvert runs

beneath this swale, so water can flow freely between the

two inner ditches even when the swale is not overtopped. When ditch levels rise above the low point in

the inner swale (altitude 3.4 ft), the swale is overtopped

and water can flow between the ditches by this route as

well. Swale-out (station 34) is the "outer" flood-relief

swale separating the inner ditch (Punamano ditch) from

the outer ditch. The altitude at its low point is 3.5 ft.

When ditch levels exceed this level the swale is overtopped and water can flow freely between the inner and

outer ditches.

Meteorology Stations

Meteorologic data were collected at stations 9, 10,

and 35 (figs. 5 and 6). Station 9 was a recording rain

gage, located at an altitude of 580 ft in the Kahuku

uplands, that recorded accumulated rainfall at 10-

minute intervals. Station 10 was operated by University

of Hawaii climatologists to collect the data required to

compute estimates of potential evaporation using the

Penman method (Penman, 1948). Multiple sensors at

the station measured rainfall, air temperature, relative

humidity, wind speed, net solar radiation, and soil heat

flux. The electronic recorder at the station read each

sensor every 5 seconds and recorded mean values every

10 minutes. The data were further summarized to hourly

and daily means (totals for rainfall) and Penman’s equation was applied to compute potential evaporation

(T.W. Giambelluca and M.A. Nullet, University of

Hawaii, written commun., 1998). Station 35 was a continuous-recording station operated by USFWS to collect rainfall and other meteorologic data in the vicinity

of the Refuge. Rainfall data from station 35 were substituted for missing rainfall data at station 10 for multiple

gaps in the record.

Ground-Water Stations

Stations 12 through 18 (fig. 8) were steel piezometers driven into ponds and ditches at the Kii Refuge.

Station 19 was a monitoring well that had been previously installed near the Kahuku sewage treatment plant.

Station 6 (fig. 8) refers to the Kii artesian wells, where

the USFWS installed totalizing flow meters in 1996 that

provide a monthly record of ground-water flow from

the three wells. Water from the Kii artesian wells is used

to maintain water levels within all ponds in the Kii Unit

except for pond E.

Ground-water levels inside the piezometers were

recorded along with concurrent measurements of pondor ditch-water levels in a separate stilling well attached

to the piezometer riser pipe. Electronic recorders with

dual pressure transducers were installed at four of the

piezometers (stations 12, 13, 15, and 17) and operated

to record water levels at a 10-minute interval. Manual

measurements were made at the other piezometers (stations 14, 16, and 18) and at the station 19 monitoring

well. Manual measurements were typically made as part

of a synoptic survey done on a single day.

Water- and Sediment-Quality Stations

Samples of water and bottom sediment were collected for analysis of organic and inorganic chemical

constituents during two surveys, a dry season survey

and a wet-season survey (table 3 and fig. 9). The dry

season survey consisted of water samples collected

from five sites and sediment samples from three sites.

Water sampling sites included the primary sources of
Sand plug

Ditch

pond

Ra boy

ditch

Raboy ditch

Ocean outlet channel

Refuge fence

Road

Punamano

Hospital ditch

Figure 8. Ground-water stations at the Kii Unit, James Campbell National Wildlife Refuge Oahu, Hawaii.

21°41'50"

157°57'30" 157°57'20"

21°41'35"

E-seaward

E-inland

A

C B

D

G

F-seaward

F-inland

Hospital ditch

A

Kii artesian

 wells

b

b

bb

b

b

12-GS

14-GS 15-GS

b 18-GS

6-W

16-GS

17-GS

19-G

13-GS

b

12-GS

19-G

EXPLANATION

DRIVEN WELL POINT (PIEZOMETER)

AND NUMBER--letter indicates type of

data collected

DRILLED MONITORING WELL AND

NUMBER--letter indicates type of

data collected

TYPE OF DATA COLLECTED:

G, Ground-water level

S, Surface-water level

W, Ground-water withdrawal from wells

a

a

PACIFIC

OCEAN

OAHU Pacific

Ocean Area

of map

0 500 1,000 FEET

0 100 200 METERS

Base from U.S. Geological Survey digital line graph maps, 

Kahuku quadrangle, 1:24,000

Data-Collection Program 19
20 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

1 Sample designation and collection method correspond to organic analyses. Cores were also collected at these sites and were subsampled at top and bottom for

inorganic major-element and trace-element analyses.

Table 3. Water and sediment samples collected for organic and inorganic chemical analyses, James Campbell National Wildlife

Refuge and vicinity, Oahu, Hawaii

[Sampling sites are shown on figure 9]

Sample

designation

Station

number Location or description

Dry-season sampling, November–December 1994

Water samples, November 22, 1994:

A 37 Punamano Spring

B 36 Punamano north pond

C 44 Kii pond C next to Punamano ditch

D 12 Kii pond D next to Punamano ditch

E 6 Kii artesian wells

Pond-bottom sediment samples, December 28, 1994:

F 36 Punamano north pond, top of sediment core

G 36 Punamano north pond, bottom of sediment core

H1 44 Kii pond C next to Punamano ditch, grab sample, top of sediment

I

1 12 Kii pond D next to Punamano ditch, grab sample, top of sediment

Wet-season sampling, March 13–14, 1997 (all water samples)

A 37 Punamano Spring

B 36 Punamano north pond

C 44 Kii pond C next to Punamano ditch

D 12 Kii pond D next to Punamano ditch

E 6 Kii artesian wells

F 3 Kii ditch at station 3

G 45 Hospital ditch at Kii Refuge fence

H 4 Kahuku storm drain at station 4

I 1 Punamano ditch at station 1

J 6 Duplicate sample from Kii artesian wells
Figure 9. Sites sampled for inorganic and chemical analysis of water and pond-bottom sediment, James Campbell National Wildlife R

EXPLANATION

Punamano Unit

Kii Unit

Limit of

marsh wetland

Ditch

Ohia Ai Gulch

Punahoolapa

marsh

Punamano

Kii Ditch

MCE Ditch

Nudist Camp Road

Marconi Road

K al aeoka

pa hi

ulc G

h

Kamehameha Highway

hcti Dl ati pso H

21°42'12"

21°41'35"

157°58'10" 157°57'20"

b

b

b

b

d

d

d

d

d

d

WATER AND SEDIMENT 

SAMPLE SITE--Number is station number

in tables 2 and 17–22

WATER SAMPLE SITE--Number is station 

number in tables 2 and 17–22

36

1

4

3

6

44

12

45

d

36

4

37

0 500 1,000 FEET

0 100 200 METERS

Base from U.S. Geological Survey digital line graph maps, 

Kahuku quadrangle, 1:24,000

Data-Collection Program 21
22 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

inflow to the Refuge during the dry season (Punamano

Spring and Kii artesian wells) and representative Refuge ponds (Punamano north pond and Kii ponds C and

D). Sediment sampling sites were located in Punamano

north pond and Kii ponds C and D. The wet-season survey consisted of water samples collected from nine

sites. Water sampling sites included the same five sites

sampled during the dry season as well as four sites

located on ditches and storm drains in the vicinity of

surface-water gaging stations 1, 3, 4, and 5 located on

Punamano ditch, Kii ditch, Kahuku storm drain, and

Hospital ditch respectively.

An extensive salinity survey of ponds and ditches

was made throughout the greater coastal plain, concentrating on the Kii and Punamano Units of the Refuge,

the connecting Punamano ditch, and known springs at

and near Punamano and Plum Tree Springs. The survey

was made using specific conductance as a surrogate of

salinity and was designed as an attempt to locate areas

of measurable ground-water seepage by detecting

abrupt contrasts in specific conductance or temperature.

Site locations and the salinity survey results are discussed in greater detail in the section of the report titled

"Ground-water/surface-water interaction."

STREAMFLOW

Water-Level Fluctuations in the Gaged

Surface-Water Bodies

Water-level hydrographs for streams, ditches, and

selected ponds are shown in figures 10 and 11 for the

period October 1996 through February 1998. This

period encompasses the year-long span of concurrent

record in 1997, as well as a severe storm in November

1996 and data collected in January and February 1998.

The water-level hydrographs include all data collected

at 10- and 15-minute intervals. Although some detail is

obscured by the compressed scales in figures 10 and 11,

the hydrographs still serve to demonstrate several key

water-level relationships of importance to the Refuge.

Hydrographs with expanded time scales are used to provide greater details in later sections of the report.

The hydrographs have different patterns that

reflect characteristics of the water bodies they measure,

such as the runoff response for upland watersheds,

downstream hydraulic factors that limit water movement, storage characteristics of the water bodies themselves, and management practices.

Stations 2 through 5 are upland gages, and their

hydrographs have short-duration spikes that quickly

return to a fairly consistent base level. These stations lie

just seaward of Kamehameha Highway (fig. 6), on an

alluvial fan that forms a transition from uplands to

coastal lowlands. Stream channels at these stations are

narrow and transmit flashy streamflows from the

uplands on to the lower coastal plain. The streams are

intermittent or nearly so: station 2 is truly intermittent,

having a dry channel much of the year, whereas stations

3 and 5 were perennial during the study but had only a

trickle of flow during dry periods. Flow from the storm

drain at station 4 also is intermittent.

The rest of the stations are lowland gages (fig. 6A),

and their hydrographs have broader storm peaks and

much longer recession times in returning to fair-weather

base levels than upland stations 2 through 5. The timing

and speed of outflow from the lowland water bodies is

governed by differences between upstream and downstream water levels and the amount of water that has

been stored in water bodies and surficial materials

upstream of the gages. Backwater resistance may be

imposed by high downstream water levels, potentially

suppressing outflow in comparison to free drainage

conditions. These factors combine to produce hydrographs that are delayed and subdued in range compared

with the upland gages.

Examples of backwater are at stations 1 and 36

when downstream Punamano ditch stage was the same

or greater than upstream stage. When that happened, the

duckbill valve at station 1 would not open and there

would be no outflow of water from Punamano marsh

past station 1 until upstream water levels rose enough

(or downstream water levels fell enough) to reverse the

gradient. Hydrographs for stations 1 and 36 also reflect

the large storage capacity of Punamano marsh and the

network of ditches that lie upstream of station 1. The

finite capacity of the station 1 duckbill to release this

stored water contributes to the slow recession in water

level at stations 1 and 36.

Kii pond B is physically isolated from adjacent

ditches by high berms, and its hydrograph (station 21,

fig. 8) varies mainly in response to rainfall (which falls

directly on the pond), evaporative loss, possible seepage

loss, and inflow-outflow controls by USFWS. An
8

64286420

12

10

8

141210

6420

Oct. Nov. Dec. Feb. Mar. May June Aug. Sept. Nov. Dec. Feb. Jan. Apr. July Oct. Jan.

1996

WATER LEVEL, IN FEET ABOVE MEAN SEA LEVEL DAILY RAINFALL,

IN INCHES

1997 1998

STATION 9UPLANDRAIN GAGE

STATION 2KALAEOKAHIPA GULCH

6.10 inches, Nov. 14, 1996

STATION 3KII DITCHSTATION 5HOSPITAL DITCH

Streamflow 23 Figure 10. Water-level hydrographs for stations 2, 3, and 5 and daily rainfall at station 9, October 1996 to January 1998, James Campbell National Wildlife Refuge, Oahu, Hawaii.
7

654321642543210

Oct. Nov. Dec. Feb. Mar. May June Aug. Sept. Nov. Dec. Feb. Jan. Apr. July Oct. Jan.

1996

WATER LEVEL, IN FEET ABOVE MEAN SEA LEVEL

6420

DAILY RAINFALL,

IN INCHESSTATION 9 UPLAND RAIN GAGE 6.10 inches, Nov. 14, 1996

1997 1998

432

5

4

3

210

STATION 36PUNAMANO PONDSTATION 1PUNAMANO DITCH

STATION 21KII POND B

STATION 7KII OUTLET DUCKBILL

STATION 8KII OCEAN OUTLET

Figure 11. Water-level hydrographs for stations 1, 7, 8, 21, and 36, and daily rainfall at station 9, October 1996 to January 1998, James Campbell National Wildlife Refuge, Oahu, Hawaii.

24 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii
Streamflow 25

important exception took place in November 1996: the

large peak in the hydrograph indicates that stormflow in

Hospital ditch flooded the pond by overtopping flashboards in the pond water-control structure (station 30).

The subsequent recession in the pond B hydrograph

indicates that a similar volume of water drained back

out of the pond as ditch water levels declined. Other

ponds at Kii Unit were similarly flooded by ditch water

during this storm.

Station 7 measured the level of Punamano ditch

near the Kii outlet pump. The main feature in this

hydrograph (fig. 8) is the fair-weather ditch level of

about 1.8 ft, which was controlled by the outlet pump

being calibrated to that level. Repetitive pumping

caused drawdown and recovery cycles of about 0.5 ft in

the ditch. Large positive spikes in the record correspond

to stormflows that forced the station 7 duckbill valve

open, releasing water to the outer ditch. Two negative

spikes also appear in the record, in February and September 1997. These were sustained periods of pumping

that were actuated manually, overriding the automatic

controls, to facilitate maintenance operations by

USFWS.

The hydrograph at station 8 (fig. 8) reflects outflow from inner ditches of the Refuge, downstream

restrictions imposed by the Kii ocean outlet channel,

and the storage capacity of the outer ditch system and

surrounding area (figs. 6 and 7). Stormwaters can overtop low berm swales in this area, effectively merging

the outer ditch with Punamano, Hospital, and Raboy

ditches, and inundating Kii ponds A and E and adjacent

lowlands. This large volume of stored water drains

slowly through the ocean outlet and fosters a slow

recession in the hydrograph, even under free outflow

conditions. Restrictions to outflow include the narrow

width of the channel, the sand plug that builds up within

the channel, and backwater resistance from the ocean.

High ocean level causes backwater resistance by lessening the hydraulic gradient from the outer ditch system to

the ocean. Flow even reverses in the outlet channel

when ocean level is high enough, with seawater flowing

back upstream into the outer ditch system. This happens

at almost every high tide when the sand plug has been

washed out and inland runoff is small. It can also happen when a sand plug is present, through a combination

of high tides and large surf that allows waves to wash up

and over the sand plug.

Runoff Volume

Principal surface-water inflows and outflows to

and from the coastal plain in the vicinity of the Refuge

were computed by month and year (table 4). Inflow is

considered to be the total discharge from outlying gages

1 through 5 into the combined lowland ditch system that

drains the coastal plain. Outflow is the total discharge at

the inner ditch terminus at Kii Unit, or the sum of outflow through the station 7 duckbill valve plus pumpage

through the Kii outlet pump (station 11). Owing to inadequacies in some of the stream-gaging data, discharge

was estimated for some months at station 2 and for all

months at station 5 by area-weighted pro-rating of station 1 discharge using drainage areas from table 1. The

estimated discharge at stations 2 and 5 amount to only

1.4 and 1.1 percent, respectively, of the total inflow

from outlying gages 1 through 5.

In 1997, stream gages measured 331 Mgal of

inflow from outlying gages and 457 Mgal of outflow.

The influence of winter stormflows is pronounced, with

most of the inflow taking place in January, March,

April, and May, and smaller to negligible amounts in

other months. This reflects the flashy, intermittent character of the streams, which flow heavily during storms,

but little or not at all during fair weather.

Ohi Ai Gulch (station 3) is the overwhelming contributor of runoff in the vicinity of the Refuge. Kalaeokahipa Gulch (station 2) is a distant second, and smaller

amounts of runoff are contributed by Punamano marsh

(station 1), Kahuku storm drain (station 4), and Hospital

ditch (station 5). Discharge at station 3 accounted for 89

percent of the 331 Mgal of inflow from outlying gages,

probably because the drainage basin for station 3 is

large (58 percent of total drainage area for stations 1

through 5), extends much farther into the rainy uplands

than other basins, and has steep terrain in the upland

part of the basin. Notably, the November 1996 discharge of 265 Mgal at station 3 equals 90 percent of the

entire year’s discharge for that station in 1997, and 80

percent of the 1997 inflow from outlying gages 1

through 5, again reflecting the overwhelming role

played by stormflows.

Outflow at the ditch terminus in 1997 was 457

Mgal, which is 125 Mgal greater than inflow from the

outlying gages. The apparent excess in outflow (125
26 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

Mgal) equates to 27 percent of the outflow and 38 percent of the inflow. Measured outflow does not include

ungaged outflow that overflowed flood-relief swales at

the ditch terminus during storms in January 1997. Inclusion of this outflow would make the excess outflow

even (a more negative balance residual). Of the measured outflow, 98 percent was through the Kii outlet

pump, with the station 7 duckbill valve only opening for

brief periods during storms.

Positive residuals (more water in than out) signify

net storage of water during the month, probably as bank

storage along the ditch reaches between the outlying

gages and the ditch terminus, and in shallow aquifers

and other surficial materials. Negative residuals signify

the delayed outflow of this stored water, as well as independent contributions of ground-water discharge from

deeper aquifers. In this scheme, the predominance of

outflow over inflow for 1997 is attributable to gains

from underlying aquifers, because surface-water

inflows and outflows should roughly balance over the

course of a year. The month of September 1997 is particularly informative (table 4): inflows were almost negligible (0.40 Mgal) yet the Kii outlet pump (station 11)

discharged 7.99 Mgal (266,000 Mgal/d), most of which

must have originated as ground-water discharge.

Outflow from Punamano Unit, measured at station

1 (inflow to Kii Unit), totalled 5.83 Mgal during 1997.

The small negative discharge values in October and

December (table 4) may simply be instrument noise

resulting from low flow velocities that approach the

precision and resolution of the flow meter, or they may

indicate small amounts of backflow through the station

1 duckbill valve, which may not close entirely or may

be held slightly open by small obstructions such as plant

debris.

1 Negative values indicate that outflow exceeds inflow

2 Discharge at Kii outlet pump was estimated as product of measured pump duration times nominal pump rating of 12,000 gallons per minute

Table 4. Monthly discharge of streams and ditches flowing in and out of the coastal plain near James Campbell National Wildlife

Refuge, Oahu, Hawaii, October 1996 through December 1997

[Values in million gallons (Mgal), except where noted in million gallons per day (Mgal/d); --, not available; e, estimated from Station 1 discharge by areaweighted pro-rating using the drainage areas in table 1; stations are shown on figure 6]

Inflow at outlying stream gages Outflow at the inner ditch terminus

at Kii Unit

Inflow

minus

outflow Month Station 1 Station 2 Station 3 Station 4 Station 5 Total Station 7 Station 11 Total 1

1996

October -- -- 2.57 -- -- 2.57 -- -- -- --

November -- -- 264.56 -- -- 264.56 -- -- -- --

December 3.47 4.63 14.04 0.32 -- 22.46 0.07 -- -- --

1997

January 2.02 15.25 113.45 1.99 e1.30 134.01 7.83 149.26 157.09 -23.08

February 0.47 e1.16 4.96 0.17 e0.30 7.06 0.01 34.84 34.85 -27.79

March 1.96 3.57 32.27 0.36 e1.27 39.43 -0.05 62.28 62.23 -22.80

April 1.03 e2.55 74.48 0.24 e0.66 78.96 0.61 61.92 62.53 16.43

May 0.35 e0.87 47.47 0.12 e0.23 49.04 0.07 39.06 39.13 9.91

June 0.00 e0.00 2.75 0.01 e0.00 2.76 0.00 16.20 16.20 -13.44

July 0.01 e0.02 7.34 0.14 e0.01 7.52 0.00 12.26 12.26 -4.74

August 0.00 e0.00 1.61 0.13 e0.00 1.74 0.00 7.65 7.65 -5.91

September 0.03 e0.07 0.26 0.02 e0.02 0.40 0.00 7.99 7.99 -7.59

October -0.02 e0.00 2.13 0.14 e0.00 2.25 0.01 11.08 11.09 -8.84

November 0.01 e0.02 1.31 0.16 e0.01 1.51 0.00 12.11 12.11 -10.60

December -0.03 e0.00 6.72 0.06 e0.00 6.75 0.00 33.79 33.79 -27.04

1997 total (Mgal)

5.83 23.51 294.75 3.54 3.80 331.43 8.48 448.44 456.92 -125.49

1997 average (Mgal/d)

0.016 0.064 0.808 0.010 0.010 0.908 0.023 1.229 1.252 -0.344
Streamflow 27

Observations Related to Stormflows and

Flooding

The lowlands of the Kahuku area flood frequently.

The most severe flood in recent times occurred in

March 1991 and caused extensive damage in the town

of Kahuku.Much of the coastal lowlands seaward of

Kamehameha Highway were inundated, and farms and

aquafarms were damaged. Flooding of the Refuge disrupted endangered waterbird nesting and maintenance

habitat, and caused the loss of nests and young. A key

factor in the March 1991 flooding may simply have

been the magnitude of the storm: the maximum 24-hour

rainfall at Kahuku during the 2-day period March 19–

20, 1991 was 17.4 inches, corresponding to a recurrence

interval in excess of 100 years in terms of rainfall (State

of Hawaii Department of Land and Natural Resources,

1984; 1991).

Reports attributed flooding to inadequate capacity

of existing channels and ocean outlets, and to water

ponding in low areas both inland and seaward of the

highway (Kahuku Flood Relief Task Force Committee,

1991; State of Hawaii Department of Land and Natural

Resources, 1993; R.M. Towill Corporation, 1997).

These reports also called for future flood mitigation

through the re-opening of lowland drainage ditches,

more frequent clearing of vegetation from existing

channels, and new drainage projects such as bridge widening and creation of new flood channels.

Stream-stage and discharge data collected during

this study provide insight into some of the factors that

govern storm runoff to and from the Kahuku coastal

plain. The scope of our investigation did not include an

exhaustive study of flooding, therefore many questions

will be left unanswered in the following discussions.

Also, the spatial coverage of gaging stations in this

study necessarily restricts insight to areas including and

immediately surrounding the James Campbell National

Wildlife Refuge.

Storms

Data for three large storms were included in the

surface-water records collected during this study. Peak

flood stages, discharges, and times-to-peak data are

summarized in table 5 for the storms of November 14,

1996, January 3, 1997, and January 19, 1997.

The largest storm during the study period was on

November 14, 1996. Heavy rains were produced by a

particularly stable low-pressure system that was

anchored by a long-wave trough that directed deep tropical moisture to Hawaii in a southwesterly flow (known

as a Kona low in Hawaii). The upland rain gage at station 9 registered 6.1 inches of rain for the day, most of

which fell in the first 2 hours after midnight. The maximum hourly rainfall was 3.6 inches, with high-intensity

rain starting at 0045 hours and continuing through 0130

hours. Rainfall-frequency maps for Oahu (State of

Hawaii Department of Land and Natural Resources,

1984) indicate that the maximum 1-hour rainfall corresponded to a 50-year recurrence interval, but the 24-

hour rainfall corresponded to only a 2-year recurrence

interval. Thus the November 14 storm was intense, but

brief, in terms of rainfall.

Peak flood stages recorded during the November

1996 storm were the highest of the study period at the

gages that were operational before the event. Peak discharges (table 5) were 910 and 1,020 ft3

/s at stations 2

and 3. These peak discharges were determined by

applying the slope-area method (Fulford, 1994) to data

collected at the stations. A comparison to flood-frequency data (Wong, 1994) and November 1996 peak

discharge data available for two continuous-record

gages operated by the USGS on nearby Kamananui

Stream (Hill and others, 1998) indicate that this flood

had a recurrence interval of about 3 to 4 years. A daily

discharge of 114 Mgal for November 14, 1996 was

computed for station 3 from its continuous stage record.

A daily discharge was not computed for station 2

because the gage was washed away in the early part of

the storm.

Flow went overbank at several points in the

streams and ditches during the November 1996 storm.

The most conspicuous out-of-channel flow was at

Kalaeokahipa Gulch at Kamehameha Highway. The

stream had gone overbank upstream of the highway,

with most of the flow being returned to the main channel by drainage swales running along the highway.

Flow exceeded the capacity of the rectangular bridge

opening beneath the highway, running over the highway and blanketing it with a layer of alluvial silt. The

capacity of the bridge opening during the flood was

reduced to some degree by woody debris, some of

which remained plastered on the upstream face of the

bridge after the storm. Most of the over-highway flow

re-entered the channel just downstream of the highway,

washing station 2 away in the process. The 12-ft long

stilling well and attached instrument shelter were found
28 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

1 As measured from start of intense rain November 14 at 0045 hours at station 9 upland rain gage2 As measured from start of intense rain January 3 at 1015 hours at station 9 upland rain gage3 As measured from start of intense rain January 19 at 2015 hours at station 9 upland rain gageTable 5. Peak stage, discharge, and time to peak stage at surface-water gaging stations during storms in November 1996 and January 1997, James Campbell

National Wildlife Refuge, Oahu, Hawaii

[Peak stage in feet above mean sea level; stages are from continuous recorders except where noted in remarks column; ft, feet; ft3/s, cubic feet per second; hr, hour; min, minute; e, estimated; <, actual

value is thought to be less than the value shown; >, actual value is thought to be greater than the value shown; --, not measured, not applicable, or none; stations are shown on figure 6]

Maximum during storm of

November 14, 1996

Maximum during storm of

January 3, 1997

Maximum during storm of

January 19, 1997

Station

number

Stage

(ft)

Discharge

(ft3/s)

Time to peak1

(hr, min)

Stage

(ft)

Discharge

(ft3/s)

Time to peak2

(hr, min)

Stage

(ft)

Discharge

(ft3/s)

Time to peak3

(hr, min) Remarks

36 6.2 -- 18 hr, 34 min 3.5 -- 19 hr, 21 min 3.5 -- 22 hr, 06 min January 3 peak somewhat

obscured by additional rain onJanuary 4

1 -- -- -- 2.9 8.7 19 hr, 25 min 3.0 7.8 24 hr, 05 min January 3 peak somewhat

obscured by additional rain onJanuary 4

2 18e 910 >0 hr, 30 min 11.4 42 1 hr, 15 min 12.6 84 1 hr, 15 min November 14 peak from surveyed high-water mark, and

time to peak is when gagewashed out

 3 11.9 1,020 1 hr, 30 min 7.2 270 1 hr, 45 min 9.4 600 1 hr, 45 min November 14 peak from surveyed high-water mark; higher

peak on January 4 after additional rain

 4 -- -- -- 4.4 24 4 hr, 35 min 5.0 40 3 hr, 35 min -- 5 7.0 -- 2 hr, 30 min 4.2 -- 4 hr, 15 min 4.8 -- 3 hr, 15 min -- 7 -- -- -- 3.8 7.2 3 hr, 25 min 4.2 9.0 3 hr, 55 min -- 8 4.8 -- 4 hr, 45 min 2.9 -- 5 hr, 35 min 3.5 -- 4 hr, 25 min --

 11 <6e -- -- 4.0 27 3 hr, 24 min 4.3 27 3 hr, 35 min November 14 peak estimated as

lower than surveyed altitude ofpumphouse floor, which wasnot inundated

 21 5.1 -- 16 hr, 0 min -- -- -- -- -- -- Pond B flooded by Hospital

ditch on November 14

 33 -- -- -- 4e -- -- -- -- -- Observed Punamano ditch

about 0.7 ft higher than innerswale and flowing upstreaminto Hospital ditch

 34 -- -- -- 4e -- __ -- -- -- Observed Punamano ditch

about 0.3 ft higher than outerswale and flowing to outerditch, which was about 0.7 ftlower than swale
Streamflow 29

more than a mile downstream in Punamano ditch. Data

were retrieved from the recorder and the last recorded

steam stage was 12.3 ft (3.3 ft water depth in channel)

at 0115 hours. The peak stage at the original location of

station 2 was estimated from high-water marks to be

about 18 ft (9 ft water depth in channel).

The station 2 stilling well and instrument shelter

came to rest in Punamano ditch, upstream (west) of its

confluence with Kalaeokahipa Gulch, indicating

upstream movement of water in Punamano ditch at this

location. This upstream flow was confirmed by the

characteristics of the silt layer deposited across Nudist

Camp Road at the future site of station 1. In addition to

crossing the road, Punamano ditch also went overbank

east of station 1, flooding adjacent ranchland in the seaward direction. The peak stage at Punamano pond station 36 during the November storm was 6.2 ft and the

altitude of Nudist Camp Road is about 6 ft.

At Kii ditch, November flow was bankfull or very

slightly overbank along the reach of ditch seaward of

Kamehameha Highway past station 3, where the flood

peak of 11.9 ft equalled 8.2 ft water depth in the channel. Hydraulic analysis using surveyed high-water

marks and stream cross sections indicates that the bankfull flow at Kii ditch resulted simply from magnitude of

the discharge and that stage at this location was not

affected by backwater (R.A. Fontaine, USGS, oral commun., 1998). Stormwater in Kii ditch also crossed the

access road to the Kii Unit, where the ditch and road

make a 90-degree turn to the west by the sewage treatment plant. The overflow entered an inactive ditch bordering a banana farm to the east of Kii ditch.

At Hospital ditch near station 5, a thin and narrow

blanket of silt across Kamehameha Highway indicated

that the bridge crossing was just slightly overtopped in

the November storm. The peak stage of 7 ft at station 5

(table 5) is essentially the same as the highway altitude

there. At station 8, the peak stage of 4.8 ft indicates that

the flood-relief swale separating inner and outer ditches

(station 34, altitude 3.5 ft) was inundated during the

November storm. This is corroborated by water levels

in the Kii ponds, because most were flooded by the

ditches. At Kii pond B (station 21), the hydrograph and

peak stage of 5.1 ft (fig. 11 and table 5) confirm pond B

was flooded, probably by Hospital ditch overtopping

flashboards in the water-control structure (station 30).

Manual staff-gage readings (M. Silbernagle, USFWS

Haleiwa office, written commun., 1999) suggest that

other Kii ponds also were flooded by ditch waters: pond

A, 4.54 ft; pond C, 5.07 ft; pond D, 5.08 ft; pond E, 5.00

ft; pond G, 5.06 ft. Taken together, the pond water levels imply peak stage of about 5.1 ft at the inner ditch terminus. Given the 0.3 ft drop in head from there to

station 8, water would have been flowing freely across

the swale from inner to outer ditch.

The storms of January 3 and 19, 1997 were of a

lesser magnitude than the November 1996 storm but

were documented more completely in that most of the

gaging stations installed for this study were operational

then. The upland rain gage at station 9 registered 2.4

inches of rain on January 3. The maximum hourly rainfall was 1.0 inches and the highest intensity rain started

at 1015 hours. On January 19 station 9 registered 3.4

inches of rain. The maximum hourly rainfall was 1.6

inches and the highest intensity rain started at 2015

hours.

Peak flood stages in January were lower than

November peak stages at all stations. January peak

stages at stations 2 and 3 corresponded to half-bankfull

flow. Similarly, peak discharges in January were

smaller than in November at stations 2 and 3 (table 5).

The outlet pump at station 11 operated continuously for

periods from one to several days during the January

storms, however it was not able to discharge sufficient

water to keep the ditches from topping the flood relief

swales at stations 33 and 34. This is clear from looking

at the peak stages at stations 7 and 11 for the January

storms, which were both higher than the altitudes of the

ditch swales. Peak stage in the Kii outlet channel at station 8 reached 2.9 ft on January 3 and 3.5 ft on January

20. Peak stages at Punamano north pond were 3.5 ft for

both January storms while peaks at station 1 were 2.9 ft

on January 3 and 3.0 ft on January 20.

Stream Response Times and Stream Gradients

During the storms of November 1996 and January

1997, streams and ditches at the various gaging stations

showed a broad range in the timing of runoff (table 5)

and in the character of the stream hydrographs (figs.

12–14). Upland stations 2 and 3 had the quickest

responses, with times-to-peak-stage of less than 2 hours

from onset of intense rain. Stations 4, 5, 7, and 8 had

slightly slower responses in the 2 to 6 hour range. Stations 1 and 36 had the longest and most variable timesto-peak, ranging from 18 to 24 hours.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

WATER LEVEL, IN FEET REALTIVE TO SEA LEVEL

10-MINUTE

RAINFALL,

IN INCHES

NOV.

0

30

20

10

1

2

4

3

5

2

4

6

8

2

6

4

8

2

8

14

2

8

14

0.0

0.4

0.8

-2

4

0

2

0.08 inches

November 19, 1996,

0130 hours

1996

30 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

STATION 9

UPLAND RAIN GAGE

STATION 2

KALAEOKAHIPA GULCH

STATION 3

KII DITCH

STATION 5

HOSPITAL DITCH

STATION 36

PUNAMANO POND

STATION 8

KII OCEAN OUTLET

HOURLY MEAN SEA LEVEL AT KANEOHE TIDE GAGE

DAILY NORTH SHORE SURF HEIGHT

Figure 12. Water-level hydrographs at stations 2, 3, 5, 8, and 36, and 10-minute rainfall at station 9, November 1996, 

James Campbell National Wildlife Refuge, Oahu, Hawaii. Also shown are hourly mean sea level at Kaneohe tide gage 

(mean of hourly values from the National Oceanic and Atmospheric Administration, accessed March 20, 1998 by 

telnet at wlnet2.nos.noaa.gov), and daily North Shore surf height (P. Caldwell, National Oceanic and Atmospheric 

Administration, written commun., 1998).
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

JAN.

1997

1

3

5

2

6

10

8

4

9

11

13

0.0

0.3

0.6

WATER LEVEL, IN FEET ABOVE MEAN SEA LEVEL

10-MINUTE

RAINFALL,

IN INCHES

Figure 13. Water-level hydrographs for stations 2, 3, and 5 and 10-minute rainfall at station 9, January 1997, 

James Campbell National Wildlife Refuge, Oahu, Hawaii.

Streamflow 31

STATION 9

UPLAND RAIN GAGE

STATION 2

KALAEOKAHIPA GULCH

STATION 3

KII DITCH

STATION 5

HOSPITAL DITCH
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

JAN.

1997

10

0

20

30

1

4

1

3

2

3

2

WATER LEVEL, IN FEET RELATIVE TO MEAN SEA LEVEL

10-MINUTE

RAINFALL,

IN INCHES

5

4

2

3

4

2

3

4

0.0

0.3

0.6

4

-2

0

2

Figure 14. Water-level hydrographs for stations 1, 7, 8, and 36, and 10-minute rainfall at station 9, January 1997, 

James Campbell National Wildlife Refuge, Oahu, Hawaii. Also shown are hourly mean sea level at Kaneohe tide 

gage (the National Oceanic and Atmospheric Administration, accessed March 20, 1998 by telnet at wlnet2.nos.

noaa.gov), and daily North Shore surf height (P. Caldwell, National Oceanic and Atmospheric Administration, 

written commun., 1998).

32 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

STATION 9

UPLAND RAIN GAGE

STATION 36

PUNAMANO POND

STATION 1

PUNAMANO DISTRICT

STATION 7

KII OUTLET DUCKBILL

STATION 8

KII OCEAN OUTLET

DAILY NORTH SHORE SURF HEIGHT

HOURLY MEAN SEA LEVEL AT KANEOHE TIDE GAGE
Streamflow 33

The rapidity with which water will be conveyed

downstream and out to sea from any point depends

largely on stream gradient. The hydraulic head drop and

average gradient from each gaging station (at the time

of its peak stage) to Kii inner ditch terminus station 7

and Kii ocean outlet station 8 are shown in tables 6 and

7. Analyses of stream gradients are useful for considering where potential backwater effects may be significant.

Using the January 3 storm values in table 6 as an

example, the largest gradients were from upland stations with the highest peak stages: station 2 at Kalaeokahipa Gulch (7.1 ft/mi) and station 3 at Kii ditch (5.1

ft/mi). In contrast, the gradient from station 5 at Hospital ditch was 0.5 ft/mi and from station 36 at Punamano

north pond it was only 0.1 ft/mi. The gradient from station 1 at Punamano ditch was negative, -0.4 ft/mi, indicating that the water level at station 7 was higher than at

station 1 and that the station 1 duckbill valve was

closed. The gradient from station 8 at Kii ocean outlet

was -3.8 ft, corresponding to a -0.9 ft head drop from the

inner ditch to the outer ditch (station 7 to station 8).

Similar relations among stream gradients were

observed during the November 14 and January 19

storms, and when gradients were referenced to station 8

(table 7) rather than to station 7 (table 6).

Stream gradient is one of the factors that affect the

timing of runoff, particularly on stream recession.

Upland stations 2 and 3 have the steepest gradients and

quickest recessions whereas stations 1 and 36 have the

smallest gradients and slowest recessions, lasting tens

of days (figs. 12–14). Other stations are intermediate

between these extremes.

Sea-Level Interactions and Potential Backwater

Effects in Lowland Areas

Stream gradients are gentle in the Punamano and

Kii Units of the Refuge and the lands along Punamano

and Hospital ditches. As a result, streamflow and flood

conditions are sensitive to any downstream restrictions

and resulting backwater effects. This topic is best discussed starting from the downstream end of the system

and working upstream.

Kii ocean outlet is the most downstream point in

the drainage network of the Kahuku coastal plain and is

important in regulating outflow from the plain. The outlet channel is narrow and a sand plug, or berm, tends to

build up in the channel (fig. 3). The plug varies in height

and lateral position in response to two main competing

stresses: (1) high surf, which favors sand deposition,

building of the sand plug, and therefore closure of the

outlet channel; and (2) high ditch flows, which breach

and wash out the sand plug (the plug is also cleared

occasionally by the USFWS using a bulldozer or backhoe). During periods of low to medium ditchflow, water

level in the Kii outer ditch system is controlled by the

height of the sand plug in the outlet channel. When the

plug is high, water will pond to greater height in the

outer ditch. In addition to being controlled by the height

of the sand plug, the outer ditch also is influenced by the

ocean in two principal ways: (1) there can be backflow

of seawater up the outlet channel during high tides,

directly when the channel is clear and by wave overwash when a sand plug is in place; and (2) high ocean

levels can impose a marine backwater influence by lessening the hydraulic gradient from the outlet channel to

the ocean, hence lessening outflow velocity and discharge.

The hydrographs in figure 15 show events at and

near the outlet during the 16-month period November

1996 through February 1998. The hydrographs show:

(1) hourly sea level at the Kaneohe tide gage; (2) daily

surf height on the North Shore of Oahu (the northwestfacing coast to the west of Kuilima Point); (3) station 8

outer ditch level near Kii ocean outlet channel; (4) station 7 inner ditch level at the terminus of Punamano and

Hospital ditches (near Kii outlet pump); and (5) station

3 stream stage at Kii ditch (a good indicator of upland

runoff).

A prominent trend in figure 15 is an apparent

season-long episode of sand-plug buildup (indicated by

a progressive increase in station 8 water level), beginning with the first high surf of the season in September

1997 and peaking in January 1998. Abrupt declines and

increases in station 8 water level in January and February 1998 indicate sand-plug washouts and clearings by

USFWS, alternating with subsequent rebuilding of the

plug by high surf. Also evident is the varying interplay

of ocean tides and pumping cycles at station 11 in causing cyclicity in the station 8 record at daily and shorter

periods. Tidal range is greatest and high tides are highest during spring tides, which occur twice a month at

full moon and new moon (for example, the several 14-

day spring-neap tidal cycles in December 1996). Pumping cycles at Kii outlet pump (station 11) produce a

mirror-image pattern in stage at stations 7 and 8: drawdown troughs at station 7 correspond to spiky peaks at
34 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

1 Station 7 pre-storm stage was 1.8 ft

2 Station 7 pre-storm stage was 2.5 ft

Table 6. Flood peaks, hydraulic head drop, and average gradient from stations to inner ditch terminus station 7 at Kii

Unit during storms in January 1997, James Campbell National Wildlife Refuge, Oahu, Hawaii

[Stages in feet above mean sea level; ft, feet; mi, mile; ft/mi, feet per mile; station 7 is at the inner ditch terminus at Kii Unit; e, estimated; station

7 stage is at the peak time for each station; head drop is the instantaneous difference in stage from each gaging station to station 7, at the peak time;

>, actual value is greater than value shown; --, not measured or not applicable; stations shown in figure 6]

Station

Distance

from station 7

(mi)

Peak stage

(ft)

Corresponding

station 7 stage

(ft)

Head drop

(ft)

Average gradient

(ft/mi)

Storm of January 3, 19971

36 1.76 3.5 3.4 0.1 0.1

1 0.97 2.9 3.3 -0.4 -0.4

2 1.19 11.4 2.9 8.5 7.1

3 0.94 7.2 2.4 4.8 5.1

4 0.79 4.4 3.8 0.6 0.8

5 0.78 4.2 3.8 0.4 0.5

7 -- 3.8 3.8 -- --

8 0.24 2.9 3.8 -0.9 -3.8

11 0.06 4.0 3.8 0.2 --

Storm of January 19, 19972

36 1.76 3.5 3.1 0.4 0.2

1 0.97 3.0 3.0 0.0 0.0

2 1.19 12.6 3.5 9.1 7.6

3 0.94 9.4 3.8 5.6 6.0

4 0.79 5.0 4.2 0.8 1.0

5 0.78 4.8 4.2 0.6 0.8

7 -- 4.2 4.2 -- --

8 0.24 3.5 4.2 -0.7 -2.9

11 0.06 4.3 4.2 0.1 --
Streamflow 35

1

 Station 8 pre-storm stage was 3.4 ft

2

 Station 8 pre-storm stage was 2.1 ft

3

 Station 8 pre-storm stage was 2.1 ft

Table 7. Flood peaks, hydraulic head drop, and average gradient from respective stations to Kii ocean outlet station 8

during storms in November 1996 and January 1997, James Campbell National Wildlife Refuge, Oahu, Hawaii

[Stages in feet above mean sea level; corresponding station 8 stage is the stage there at the peak time for each upstream station; head drop is the

instantaneous difference in stage from each gaging station to station 8 at the peak time for the upstream station; mi, miles; ft, feet; ft/mi, feet per

mile; e, estimated; --, not measured or not applicable; stations shown in figure 6]

Station

Distance

from station 8

(mi)

Peak stage

(ft)

Corresponding

station 8 stage

(ft)

Head drop

(ft)

Average gradient

(ft/mi)

Storm of November 14, 19961

36 1.94 6.2 3.7 2.5 1.3

2 1.37 e18 3.5 14.5 10.6

3 1.12 11.9 3.7 8.2 7.3

5 0.89 7.0 4.3 2.7 3.0

8 -- 4.8 4.8 -- --

Storm of January 3, 19972

36 1.94 3.5 2.8 0.7 0.4

1 1.15 2.9 2.8 0.1 0.1

2 1.37 11.4 2.6 8.8 6.4

3 1.12 7.2 2.5 4.7 4.2

4 0.91 4.4 2.8 1.6 1.8

5 0.89 4.2 2.8 1.4 1.6

7 0.24 3.8 2.8 1.0 4.2

8 -- 2.9 2.9 -- --

11 0.22 4.0 2.7 1.3 5.9

Storm of January 19, 19973

36 1.94 3.5 2.5 1.0 0.5

1 1.15 3.0 2.4 0.6 0.5

2 1.37 12.6 2.5 10.1 7.4

3 1.12 9.4 2.6 6.8 6.1

4 0.91 5.0 3.4 1.6 1.8

5 0.89 4.8 3.3 1.5 1.7

7 0.24 4.2 3.5 0.7 2.9

8 -- 3.5 3.5 -- --

11 0.22 4.3 3.4 0.9 4.1
Nov. Dec. Jan. Feb. Mar. Apr. May June

42054321

-1

-2

321

10

00

3020

9876543

10

1996 1997

WATER LEVEL, IN FEET RELATIVE TO MEAN SEA LEVEL

STATION 3 Ð KII DITCH

STATION 7 ÐÊKII OUTLET DUCKBILL

STATION 8 ÐÊKII OCEAN OUTLET

HOURLY MEAN SEA LEVEL AT KANEOHE TIDE GAGE

DAILY NORTH SHORE SURF HEIGHT

Figure 15. Stream, ocean, and pumping influences on Kii ocean outlet for the 16-month period November 1996 to February 1998, James Campbell National Wildlife Refuge, Oahu, Hawaii. Shown are water-level hydrographs for stations 3, 7, and 8, hourly mean sea level at Kaneohe tide gage (National Oceanic and Atmospheric Administration, accessed March 20, 1998 by telnet at wlnet2.nos.noaa.gov), and daily North Shore surf height (P. Caldwell, National Oceanic and Atmospheric Administration, written commun., 1998).

36 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii
July Aug. Sept. Oct. Nov. Dec. Jan. Feb.

30201010

4321

-2

76543

20

STATION 3 Ð KII DITCH

STATION 7 ÐÊKII OUTLET DUCKBILL

STATION 8 ÐÊOCEAN OUTLET

HOURLY MEAN SEA LEVEL AT KANEOHE TIDE GAGE

DAILY NORTH SHORE SURF HEIGHT 30 ft. on January 28

20

1997 1998

WATER LEVEL, IN FEET RELATIVE TO MEAN SEA LEVEL

Figure 15. Stream, ocean, and pumping influences on Kii ocean outlet for the 16-month period November 1996 to February 1998, James Campbell National Wildlife Refuge, Oahu, Hawaii. Shown are water-level hydrographs for stations 3, 7, and 8, hourly mean sea level at Kaneohe tide gage (National Oceanic and Atmospheric Administration, accessed March 20, 1998 by telnet at wlnet2.nos.noaa.gov), and daily North Shore surf height (P. Caldwell, National Oceanic and Atmospheric Administration, written commun., 1998)--Continued.

Streamflow 37
38 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

station 8 as the Kii outlet pump transfers water from the

inner to outer ditch. Pumping cycles are clearly seen in

April 1997, with some high-tide influence superimposed. The length of time between pumping periods

shortens dramatically when the Kii outlet pump must

transfer stormwaters to the outer ditch, and pumping

cycles disappeared entirely in the station 7 and 8 hydrographs for several days during the storms of November

1996 and January 1997, indicating that the pump was

operating continuously. Pumping cycles were closely

spaced in December 1997 and January 1998, when the

outer ditch level was high. Wave washover of the sand

plug during high surf is evident on September 23 and

October 28, 1997. Except for these two events, the sand

plug appears to have been high enough from late September through December 1997 to prevent high-tide

overwash of the plug (there is a general absence of hightide peaks in the station 8 hydrograph during this

period).

During the entire 16-month period, the water level

at Kii ocean outlet station 8 never dropped below 1.48

ft above sea level. Furthermore, high-tide peaks are evident in the record but low-tide troughs in the water level

are not symmetrically commensurate: the record is flatfloored, as if the bottom half of the tidal cycle were

blocked from having any influence. Factors that may

contribute to this include: the outlet channel has a hard

limestone or beachrock bottom that may act as a weir; if

so its altitude may be about 1.48 ft; the outer ditch system just inland of the outlet channel is lined with mud

that may inhibit infiltration and fall of outer ditch level

below some minimum limit; the shallow ground-water

table in the vicinity may act as a lower limit.

Some of the processes discussed above are more

distinguishable in hydrographs with expanded time

scales (figs. 12–14). The pronounced peaks in the station 8 hydrograph at daily frequency are high-tide episodes of wave overwash or direct seawater backflow up

the ocean outlet channel (clearly identifiable in fig. 12,

November 9–12 and November 24–December 1, and

throughout most of fig. 14). The highest-frequency

"noise" in the station 8 hydrograph, with periods on the

order of hours or less, reflects cyclic pumping by the Kii

outlet pump (seen most clearly in fig. 14 on January 1–

2 and 15–18). Pumping-cycle noise is absent in the station 8 hydrograph from late evening November 12

through November 19 (fig. 12) and in both stations 7

and 8 hydrographs during the January flood peaks

(fig. 14). This signifies that the outlet pump was not

cycling during these periods, but instead was operating

continuously in an attempt to transfer floodwaters from

inner to outer ditch.

Events surrounding the November 14 storm (fig.

12) at the ocean outlet are significant because they illustrate several key factors affecting drainage at the outlet.

A gradual rise in station 8 ditch level from November 9

to 12 corresponds to a 4-day period of high surf. This

could represent either a gradual buildup of the sand plug

in the outlet channel or progressively higher ocean levels resulting from "wave setup," a super-elevation of

local sea level by waves piling up at the shore. The gradual rise in station 8 stage over this 4-day period is punctuated by high-tide peaks of wave overwash or seawater

backflow in the channel. The station 8 hydrograph

shows rapid pump cycling on November 5–6 and on

November 8–12 in response to the small rainstorms on

November 5, 8, and 12–13. The absence of cycling on

November 8 indicates that the outlet pump was operating continuously to dispose of stormwater. The pump

also operated continuously from late evening November 12 through November 13, with no rise in station 8

stage (actually, there was a 0.26-ft drop during this

period). The fact that the pump was transferring water

into the outer ditch at a rate of 12,000 gal/min (17.2

Mgal/d) with no rise in outer ditch stage suggests that

the sand plug had been washed out by this continual

flow, or that the pump was recirculating outer-ditch

water that was flowing inward over the outer floodrelief swale. If a sand plug were still present just before

the November 14 storm peak, it would have washed out

early in the storm and would not have been present at

the times of the flood peaks at the inland gaging stations. Following the November 14 storm peak, station 8

stage declined gradually to about 1.6 ft by the end of

November, with the outlet pump operating continuously through November 19 and cycling rapidly thereafter. Notably, the November 14 storm coincided with

the highest surf of the month (25 ft) and occurred about

2 days after spring tide. Thus, the high outer ditch levels

before and during the November 14 storm were probably caused by remnant stormwater from small rainstorms earlier in the month and a marine backwater

effect from high ocean levels that hindered outflow. The

high ocean levels were due to the coincidence of spring

high tides and wave setup from large surf.
Streamflow 39

Whether high levels in the ocean and outer ditch

contributed to backwater effects farther upstream in

November 1996 is difficult to determine. Station 7 definitely did not experience a backwater effect from the

outer ditch during the January storms. Peak stage was

0.7 to 1.0 ft higher in the inner ditch at station 7 than at

station 8 (table 7), resulting in a hydraulic step-down

over the outer flood-relief swale. But on November 14,

the pre-storm stage in the outer ditch at station 8 was 3.4

ft, compared with 2.1 ft for the January storms (see footnotes, table 7). Thus, the inner ditches were working

against an additional 1.3 ft of water in conveying runoff

out of the coastal plain during the November 14 storm.

This may have contributed to backwater effects at station 7 and points farther upstream. The outer ditch level

peaked at 4.8 ft during the November storm and the

inner ditch level peaked at about 5.1 ft (stations 8 and

21, table 5). Presuming that these peaks were coincident

in time, the small head drop of 0.3 ft from the inner ditch

to station 8 makes it difficult to judge whether the head

drop represents a hydraulic step-down over the outer

flood-relief swale; a gradient corresponding to free,

unhindered outflow; or a gradient reflecting backwater

influence. To discriminate among these possibilities

would require detailed hydraulic modeling and analysis

that are beyond the scope of this study.

A backwater effect was evident at station 1 in both

January storms. Table 6 shows that at the time-of-peak

at station 1, the stage at station 7 downstream was either

higher than or equal to station 1 stage, and that the gradient between the two stations was flat (January 19) or

even negative (January 3). Figure 14 shows that the

head disparity was even greater at earlier times, prior to

the station 1 time-of-peak when station 7 stage was

higher. In fact, the stage at station 7 was a full foot

higher than at station 1 early on January 20. During

periods of backwater at station 1, the duckbill valve

closes and no discharge occurs. Therefore, water goes

into storage in Punamano marsh, raising water levels

there (see station 36, fig. 14). In the January storms, this

stored water began to drain only when stage at station 7

had declined sufficiently to allow the station 1 duckbill

valve to reopen, typically a day or two after the start of

the storm. The November 1996 storm caused a more

extreme backwater effect on Punamano marsh, when

floodwaters in Punamano ditch overtopped Nudist

Camp Road and flowed back upstream into the marsh.

This phenomenon has water-quality implications for

Punamano Unit in that the floodwaters would transport

high concentrations of suspended sediment to the marsh

and potentially other contaminants such as nutrients,

pesticides, and volatile organic compounds.

The low altitude of Hospital ditch at Kamehameha

Highway may subject it to backwater effects from farther downstream. Stations 4 and 5 were not subjected to

fully flat backwater conditions in January (table 6 and

fig. 13). However, the magnitude of head drop to station

7 during the January storms was small (only 0.4 to 0.8

ft) and the times-to-peak at stations 4 and 5 strongly

indicate backwater as having an effect (that is, they are

nearly the same as at stations 7 and 11, instead of the

much shorter times that could be expected from such

small watersheds). Thus, the times-to-peak-stage at stations 4 and 5 may reflect the backing-up of water in

Hospital ditch more than the actual peak flows being

conveyed down their drainages. Field observations

were made at the flood-relief swales at the inner ditch

terminus on January 3, and backflow was noted at the

inner swale (station 33), with water flowing from

Punamano ditch back upstream into Hospital ditch (see

remark for station 33, table 5). This likely reflects the

overwhelming contribution of runoff to Punamano

ditch from Ohia Ai and Kalaeokahipa Gulches owing to

their larger watersheds. Such backflow will cause a

backwater effect in Hospital ditch, possibly as far

upstream as Kamehameha Highway, and could contribute to localized flooding there. The risk for flooding

would be greatest if high downstream water levels coincided with peak flows coming down the Hospital ditch

drainage. Backwater is not likely to have played a role

in the slight flooding of Hospital ditch at Kamehameha

Highway during the November 14 storm. The flooding

across the highway appeared to result from blockage or

exceedance of culvert capacity at the upstream side of

the highway. Downstream of the highway, head

dropped 2.2 ft from station 5 to station 8 (table 7),

equalling a gradient of 3.0 ft/mi. This is greater than the

gradient of the stream channel, and likely corresponds

to free drainage, unimpeded by backwater.

At upland stations 2 and 3, it is unlikely that backwater effects existed during the November or January

storms. Head drop from these stations to downstream

stations 7 and 8 exceeded 4 ft for all storms and stream

gradients were the steepest of all the stations (tables 6

and 7).
40 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

GROUND-WATER/SURFACE-WATER

INTERACTION

Ground-water/surface-water interaction refers to

the exchange of ground water with pond and stream

waters across the sedimentary interface at the pond or

stream bottom. Topics of particular relevance to the

hydrology of the James Campbell National Wildlife

Refuge are:

1. the degree to which stream and ditchflows in the

greater coastal plain are maintained by groundwater discharge from the Koolau aquifer or by

diffuse seepage from surficial sediments;

2. the degree to which Punamano Unit is fed

laterally by springs and seeps at the inland

margin of the marsh, compared with being fed

by upward ground-water seepage through its

pond bottoms; and

3. the degree to which Kii Unit ponds are fed by

upward ground-water seepage or, conversely,

the degree to which the ponds lose water by

downward seepage or lateral seepage through

the bordering ditch levees or berms.

Consideration of these issues requires a combination of regional- and local-scale interpretations. Therefore, a discussion of regional-scale hydrogeology is

given before focusing in greater detail on the specific

processes and geologic materials in the immediate subsurface beneath the ponds.

Regional-Scale Hydrogeology

Interpretations of the hydrogeology and depositional history in the vicinity of the Refuge area can aid

in understanding the nature of ground-water flow from

the regional ground-water flow system to the Refuge.

Such interpretations can be made mainly from the geologic map of Oahu and its accompanying report

(Stearns, 1939; Stearns and Vaksvik, 1935; a portion is

reproduced in figure 16), and from a hydrogeologic

cross section (fig. 17) derived from drilling logs and

hydrologic data for wells in the area (unpub. data at the

U.S. Geological Survey, Honolulu, Hawaii).

Principal Hydrogeologic Units

Just inland of the coastal plain in figure 16 are

extensive uplands of Koolau Basalt (Tkb), which consists of lava flows, minor ash beds, and intrusive dikes

of Pliocene to Pleistocene age (Doell and Dalrymple,

1973; Langenheim and Clague, 1987). Koolau Basalt

extends thousands of feet below sea level and constitutes the highly permeable and regionally extensive

Koolau aquifer (Hunt, 1996). Recharge in the Koolau

uplands maintains a meteoric flow system within the

aquifer, in the form of a freshwater lens that grades

through a diffuse mixing zone into underlying saltwater

(fig. 17). The coastal plain lies at the northern terminus

of this flow system, and freshwater from the Koolau

aquifer discharges upward into the overlying coastalplain sediments. Intensive weathering of Koolau Basalt

has left a mantle of readily erodible red soil and saprolite tens of feet thick over much of the uplands. One

effect of the weathering is that alluvium washed from

the uplands onto the coastal plain is mainly silty clay

having low hydraulic conductivity.

Mapped sedimentary units in figure 16 include reef

limestone (Pls), calcareous beach and dune sands (Rs,

Rd), lithified calcareous dunes (Pd), and basaltic alluvium (Pa, Ra). The lithified dunes form low hills, most

of which lie inland of Kamehameha Highway. One of

these dunes (denoted as "Punamano Bluff") caps a

sequence of raised Pleistocene reefs that overlie a subsurface ridge of Koolau Basalt (Stearns, 1970).

Although not specifically mapped in figure 16, one

can postulate the presence of additional sedimentary

lithofacies beneath the coastal plain from knowledge of

modern depositional environments and drilling logs on

Oahu. These include coralline rubble and calcareous

sands that are associated with coral reefs; back-reef

lagoonal sands, muds, and marls; and coarse beach rubble of mixed coral and basalt clasts that is deposited at

the base of sea cliffs. Stearns (1970) identified such

beach rubble in a detailed mapping of lithologic units at

Punamano Bluff, and this information is incorporated in

figure 17.

Reef limestone and associated calcareous deposits

have high hydraulic conductivity (comparable to that of

Koolau Basalt) and constitute patchy to extensive aquifers within the coastal-plain sequence. Alluvium, muds,

and marls have low hydraulic conductivity and constitute confining units. Drilling logs for wells 4057-11 and

4057*01–06 were detailed enough to identify multiple

limestone aquifers and intervening confining units (fig.

17). However at other wells, only limestone was penetrated within the depth of drilling (4257-01, 4157-09,
       





  







  

 























Pls

Pa

Pa

Pa

Pd

Pd

Pd

Pd

EXPLANATION
     



?

?















 200 100 Sea level -100 -200 -300 

     

?



















FEET

200100

Sealevel

-100-200-300

     

?

?



















FEET

FEET

100

Sealevel

-100-200-300Cl 2,800e (1980) Cl 16,000e (1980) Pls+Ps(?) Pls Pls Pls Pls+Pa(?) Pls+Pa(?)

Pls+Pa(?) Cl 1,900e (1997) Cl 2,700e (1997)

Pls+Pa(?) Pls+Pa(?)

Cl 3,300e (1980)

Cl 16,000e (1980)

Tkb

Tkb

Tkb

Tkb

Tkb

Tkb

Tkb

Tkb

Tkb

Pls

Pls+Pa(?)

Pls(?)

Pls

Pls

Pls

Pls

Pd

Pd

Rd

Rs

Rd Rs Ra

Pa

Pa

Ra

Ra

4057-11

4057*01-06

(wastewater injection wells)

STATION

19

STA 13

4157-05-07

(Kii wells)

4157-11

4157-07

4157-01

4157-01

4157-08

4157-08

4157-09

(projected)

4157-03

(projected)

STA TION 14

(projected)

TEST BORING

(projected)

4257-01

4158-11

4157-04

Cl 332 (1939)

Cl 610 (1939) Cl 78 (1932) Cl 105 (1929) Cl 136 (1997)

Cl 332 (1939)

Solid casing

Open hole

to -410 to -318

to -399 to -326 to -352

to -410

Cl 3,300e (1980)

Cl 136 (1997)

Cl 84 (1937)

Back-reef

margin

Back-reef

margin

Back-reef

lagoon

Paleo-valley

Paleo- valley

Back-reef

lagoon Beach rubble

contemporaneous

with Pls(?)

Beach rubble

contemporaneous

with Pls

Weathered basalt

Punamano Bluff

? ?

? ? ? ?

?

? ?

? ? ?

Figure 17. Hydrogeologic cross sections of the Kahuku area near James Campbell National Wildlife Refuge, Oahu, Hawaii.

Vertical exaggeration x4

Vertical exaggeration x4

Vertical exaggeration x4

0 500 1,000 FEET0 100 200 METERS

EXPLANATION

CHLORIDE CONCENTRATION

IN MILLIGRAMS PER LITERAND YEAR MEASURED--e indicates value is estimatedfrom specific conductance

GEOLOGIC UNIT--see figure 16

for explanation

WELL NUMBER, NAME, OR

DESIGNATION

A'

A

B

C

C'

B'

Kii Unit Ponds

Kii Unit Ponds

(Kii wells)

Weathered basalt

Weathered basalt

Pls

Pls+Pa(?)



42 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii
Ground-Water/Surface-Water Interaction 43

Test Boring) or there was no lithologic log but the depth

of solid casing was known (4157-01, 4157-03), which

typically coincides with the top of the Koolau Basalt in

this area. Thus, the actual stratigraphy within the

coastal-plain sediments may be more complex than is

portrayed in figure 17. Where limestone aquifers have

been tapped by wells near the coast, they contain saline

or brackish water. Sediments farther inland probably

contain freshwater, particularly in higher parts of the

alluvial fans, but no wells are situated properly to verify

this.

The coastal-plain sediments confine the underlying Koolau aquifer, resulting in a confined potentiometric surface with heights of 10 to 15 ft above sea level in

the vicinity of the Refuge, and unconfined water-table

heights of 12 to 20 ft farther inland. If the coastal-plain

sediments were absent, water levels in the Koolau aquifer would likely be only 2 to 3 ft above sea level, as is

the case several miles to the southwest where the

Koolau aquifer has been stripped of sediments by

marine abrasion (Takasaki and Valenciano, 1969).

Coastal-plain sediments are called "caprock" in Hawaii,

in view of their confining effect on the volcanic-rock

aquifers. Weathering of the uppermost several tens of

feet of the Koolau aquifer may also contribute to its

confinement. At the Kii artesian wells (4157-05–07) the

land surface is about 6 ft above sea level and the potentiometric head in the wells is about 12 ft, which allows

the wells to flow freely.

Sedimentary Depositional Sequence and

Paleoenvironment

The depositional sequence of sedimentary deposits

in the vicinity of the Refuge can be reconstructed from

the preceding information and from established principles. Much of the Kahuku coastal plain is occupied by

an emerged Pleistocene reef (the large expanse of limestone seaward of Punamano ditch in figure 16) that was

deposited during the last interglacial highstand of sea

level about 120,000 to 125,000 years ago (Stearns,

1970; 1978). The raised reefs at Punamano Bluff (and

probably some of the deeper sediments in the coastal

plain) were deposited earlier, in mid-Pleistocene time.

From Stearns' (1970) detailed mapping, it is apparent

that the sea cut a marine abrasion platform into raised

reefs and Koolau Basalt at Punamano Bluff during the

last interglacial high stand of the sea. Various interstream ridges of Koolau Basalt in the area would have

been sea cliffs that were being undercut by waves at that

time, and permeable coral reef and beach rubble would

have been deposited directly on Koolau Basalt at the

base of such cliffs, with the high-energy nearshore environment precluding deposition of any intervening lowpermeability muds. Coral reefs would have extended

offshore from the ridges, possibly merging offshore to

form the large, seaward reef tract of limestone in figure

16.

At the same time, reef channels or embayments

would have been aligned with the valleys, where the

flow of fresh stream water and suspended sediment

inhibited coral growth. In fact, Kii marsh probably

marks a deep channel or back-reef lagoon that existed

during the last interglacial and was later filled with alluvial mud (see fig. 17, sections B-B′ and C-C′, where 110

ft of alluvium, made up of brown, silty clay, overlie

weathered Koolau Basalt to 104 ft below sea level at Kii

wells 4157-05–07). Inland from Kii Unit, a paleo-valley

is apparent at well 4157-04 (fig. 17, section B-B′), perhaps the ancestral drainage of Ohia Ai Gulch or Kalaeokahipa Gulch, both of which drain in this direction. A

similar valley or reef channel may have existed in the

vicinity of Punamano marsh, representing the ancestral

drainage of Punahoolapa Gulch. This model of an

extensive offshore reef tract with back-reef lagoon and

reef channels is similar to the present configuration of

Kaneohe Bay, farther south on the east coast of Oahu.

Sea level fell several hundred feet during the subsequent glacial stage lasting about 100,000 years,

exposing the interglacial marine deposits. During this

time, streams emerging from the uplands deposited

their sediment load on the low-gradient coastal plain,

forming prominent alluvial fans at the mouths of their

valleys (the large area of alluvium in fig. 16), and perhaps filling in former reef channels and back-reef

lagoons. The fans probably contain a large fraction of

basaltic sand, gravel, and cobbles near the valley

mouths, but the distal parts of the fans between Kamehameha Highway and Punamano ditch are composed

mainly of compact, silty clay. The dune fields and beach

sands near the present coast probably were deposited

following the post-glacial Holocene rise of the sea to its

present level about 6,000 years ago. The dune fields and

alluvial fans obscure many of the key geologic contacts

of the last interglacial marine transgression.
44 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

Nature of Ground-Water Discharge from the Koolau

Aquifer

A key issue in this study is the extent to which

ground-water discharge from the Koolau aquifer supplies water to the marshes of the Refuge. An explanation for the natural occurrence of Kii marsh is that it

overlies a thick accumulation of channel-fill muds, and

that ongoing compaction of the muds results in continued subsidence, maintaining this area as one of the lowest parts of the coastal plain. This is supported for at

least the inland half of Kii Unit, given the 110-ft thickness of silty-clay alluvium at the Kii artesian wells.

Ground-water seepage from the Koolau aquifer into the

Kii ponds is likely to be small because of the low

hydraulic conductivity of the intervening muds and

clays.

An alternative hypothesis is required for

Punamano marsh, much of which lies within limestone

terrain. The ponds here may persist by dissolution of

underlying calcareous material, fostered by organic

decomposition and perhaps by upward seepage of freshwater from the underlying Koolau aquifer through reef

limestone. The area around Punamano and Plum Tree

Springs (fig. 2) appears to be a zone of concentrated discharge from the Koolau aquifer. This apparent zone of

discharge, which likely is a principal source of water to

the Punamano ponds, may be related to a buried ridge

of Koolau Basalt that extends seaward from Punamano

Bluff. Subsurface discharge from the Koolau aquifer

probably enters beach rubble and limestone near Kamehameha Highway, subsequently flowing laterally

toward the coast in the sediments. Some of the water

emerges through a thin cover of alluvium near the

inland edge of Punamano marsh (note that in fig. 16

Punamano Spring and the inland edge of the marsh are

located about where the alluvium thins out to a feather

edge).

Preferential ground-water discharge is to be

expected just seaward of other bluffs or ridges of

Koolau Basalt, most of which lie at the slope break

between uplands and coastal plain. During the present

study, base flow in Hospital ditch was traced upstream

near a mapped outcrop of reef limestone at the base of

the ridge of Koolau Basalt just west of the extensive

lithified dune in figure 16. This bluff is similar to

Punamano Bluff, apparently with similar preferential

discharge from the Koolau aquifer. The flow here represents a direct contribution from the Koolau aquifer to

the base flow of upper Hospital ditch.

Contributions to Ditch Base Flow from Surficial

Sediments

In addition to ground-water discharge from the

Koolau aquifer, discharge from surficial sediments provides another source of water to the lowland ditches.

During this study, year-round streamflow was observed

in Kii ditch at station 3 and in Hospital ditch at station

5. Flow was just a trickle during the dry season, however. Some of the flow at station 5 may have originated

from the Koolau aquifer at the head of Hospital ditch.

Regarding station 3, however, periods of no flow were

observed at Kamehameha Highway bridge about 200 ft

upstream, proving that Kii ditch gains base flow from

alluvium in the reach between the highway and the

gage. Streambeds at stations 3 and 5 are at altitudes of 2

to 3 ft above sea level and intercept the water table in the

alluvium.

During repeated field visits to stations 3 and 5

throughout the year, a season-long recession of fairweather low flow was visually apparent. This long

recession probably represented sustained ground-water

seepage from the thick alluvial fans, which had become

saturated by heavy storms in November 1996 and January 1997. Inactive aquaculture ponds located on the

alluvial fans were filled by the storms and required

months of evaporation and infiltration to empty. In the

aftermath of the wet season, bank seepage was visible

part way up the steep bank of Kii ditch near station 3,

several feet above the stream level. All lowland ditches

that intersect the alluvial fans probably gain from

ground-water seepage; however, this process was only

observed along Kii ditch where there was no obscuring

vegetation. Gains in ditchflow from the alluvial fans

may form a substantial fraction of the 45 Mgal excess of

stream outflow over stream inflow during 1997 (table

4).

In contrast, the streambed of Kalaeokahipa Gulch

at station 2 was always dry during fair weather. The

streambed altitude there is 9 ft above sea level, which

apparently is not low enough to incise into the shallow

water table in the alluvium.
Ground-Water/Surface-Water Interaction 45

Pond-Scale Hydrogeology of the Punamano

and Kii Units

All of the ponds at the Punamano and Kii Units are

underlain by several feet of black, organic-rich mud.

The material beneath the organic mud at Punamano

Unit is uncertain. At Kii Unit, the geologic log for the

Kii artesian wells 4157-05–07 shows that the inland

part of Kii Unit is underlain by 110 ft of alluvial clay.

The geologic cross section (fig. 17) indicates that the

thickness of alluvial deposits decreases seaward of the

wells, and that reef limestone and associated calcareous

sediments underlie the seaward parts of Kii Unit.

Hydrogeologic conditions in the shallow subsurface underlying the Kii Unit were studied by driving

short-screened, steel piezometers to probe subsurface

materials, and by recording water levels in these piezometers and in the overlying ponds and ditches. Locations of the piezometers are shown in figure 8, and table

8 contains the driving logs. The open, or screened, interval on the piezometers was 1 ft long, 0.5 to 1.5 ft from

the driving tip.

Most of the piezometers felt as if they penetrated a

layer of stiff, silty-clay alluvium beneath an upper layer

of soft mud that ranged from 1.4 to 7.8 ft thick. At the

more seaward piezometers (stations 12, 13, and 17) it

was possible to develop good hydraulic connection

between the wells and permeable material beneath the

alluvium, which was probably calcareous sand or coralline rubble. Very hard material caused refusal to driving

at stations 13 and 17 at depths of only 4 to 5.5 ft, and

was probably coralline rubble or reef limestone. This is

consistent with the nearby surface outcrop of reef limestone just to the north of these sites. The remaining piezometers had poorer hydraulic connection with

subsurface materials: their screens had either gotten

smeared with clay during driving or were simply open

to clay at their final depths. These piezometers were

driven to depths of 10.4 to 12.8 ft.

Four piezometers were outfitted with water-level

recorders, and three of these (stations 12, 13, and 17)

showed ground-water tides with maximum ranges of

2.2 to 2.4 ft (fig. 18). This equates to 73 to 80 percent of

the ocean tidal range, as measured at the Kaneohe tide

gage, indicating little attenuation of the tidal signal in

the aquifer over distances of 1,100 to 2,200 ft inland

from the ocean. In contrast, no tidal fluctuations were

observed in the surface-water bodies at the piezometers.

Surface-water hydrographs vary smoothly over several

months except for station 13 which reflects the characteristic cycling pattern of the Kii outlet pump.

Daily means of the water-level data were calculated to filter out the tides and pumping cycles. Graphs

of these data (fig. 19) clearly indicate the separate

behavior of the surface- and ground-water bodies at stations 12, 13, and 17. Water-level trends are parallel at

station 15, probably because the piezometer is screened

in silty-clay alluvium and does not tap the carbonate

aquifer that stations 12, 13, and 17 tap.

Table 8. Logs of driven ground-water piezometers at the Kii Unit of James Campbell National Wildlife Refuge, Oahu, Hawaii

[Values are altitudes in feet above or below mean sea level, except for depth, which is in feet below pond or ditch bottom; --, not measured or not applicable;

stations shown in figure 8]

Reference level and selected

characteristics

Station 12

pond D

Station 13

Punamano

ditch

Station 14

pond D

Station 15

pond C

Station 16

Hospital

ditch

Station 17

pond A

Station 18

pond F

Top of casing 7.03 6.79 6.01 8.94 4.73 6.17 5.57

Pond or ditch water level just after driving 3.2 1.8 3.0 3.8 1.8 1.4 4.0

Pond or ditch bottom; soft muck 1.8 -0.2 2.6 3.3 0.6 0.7 3.4

Compact; refusal to manual pushing -6.0 -2.4 -1.0 -3.7 -2.7 -2.3 2.0

Harder, more compact -6.9 -3.2 -6.5 -7.1 -5.9 -4.2 -7.4

Ringing or refusal to driving -- -4.2 -- -- -- -4.8 --

Stopped driving; bottom of wellpoint -9.8 -4.2 -9.0 -7.1 -10.3 -4.8 -9.4

Midpoint of wellscreen (1 foot above tip

of wellpoint)

-8.8 -3.2 -8.0 -6.1 -9.3 -3.8 -8.4

Hydraulic connection of wellscreen with

surrounding materials

good good poor poor very poor good poor

Depth of well point, below pond or ditch

bottom

11.6 4 11.6 10.4 10.9 5.5 12.8
-1

1

0

2

3

Sep.

WATER LEVELS, IN FEET RELATIVE TO SEA LEVEL

Oct.

1997 1998

Nov. Dec. Jan.

STATION 17

POND A

STATION 17

GROUND WATER

STATION 15

POND C

STATION 15

GROUND WATER

STATION 13

PUNAMANO DITCH

STATION 13

GROUND WATER

STATION 12

POND D

STATION 12

GROUND WATER

1

2

3

4

3

2

4

5

2

3

4

5

-1

1

0

2

3

2

3

4

-1

3

2

1

0

Figure 18. Ground-water levels in piezometers and surface-water levels in overlying ponds and ditches, 

September 1997 to January 1998, at Kii Unit, James Campbell National Wildlife Refuge, Oahu, Hawaii.

46 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii
Sep.

WATER LEVEL, IN FEET RELATIVE TO SEA LEVEL

Oct.

1997 1998

Nov. Dec. Jan.

STATION 17

POND A

STATION 17

GROUND WATER

STATION 15

POND C

STATION 15

GROUND WATER

STATION 13

PUNAMANO DITCH

STATION 13

GROUND WATER

STATION 12

POND D

STATION 12

GROUND WATER

2

4

3

1

0

2

3

5

4

2

3

1

0

1

0

2

3

4

Figure 19. Daily mean ground-water and surface-water levels in piezometers and overlying ponds and ditches, 

September 1997 to January 1998, at Kii Unit, James Campbell National Wildlife Refuge, Oahu, Hawaii.

Ground-Water/Surface-Water Interaction 47
48 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

Synoptic water-level surveys were done at the network of piezometers, at nearby stream gages, and at

USFWS pond staff gages on September 5, October 7,

and December 10, 1997 (table 9). Daily mean levels

were reported for stations equipped with water-level

recorders in order to average out tidal and pumping

cycles and short-term variability in pond levels. Several

interpretations emerge from the more complete surveys

in October and December:

1. the potentiometric level in the underlying

carbonate aquifer was 1.3 ft above sea level in

October and 1.0 ft in December; levels agreed

to within 0.1 ft among stations 12, 13, and 17;

2. surface-water levels were higher than groundwater levels at all locations except stations 16

and 18;

3. pond levels ranged between about 3 to 4 ft,

except for ponds A and E, which were less

than 2 ft in October and less than 3 ft in

December;

4. inner ditch levels (stations 7, 11, 13, and 16)

were maintained at 1.8 ft or less by the Kii

outlet pump and were lower than water levels

in the adjacent ponds; and

5. outer ditch level at station 8 was 1.8 ft in October

(lower than levels in adjacent ponds A and E)

and 3.0 ft in December (higher than levels in

adjacent ponds A and E).

Most of these relations are depicted schematically in

figure 4.

Ground-Water and Surface-Water Salinity at Kii

Unit Piezometers

Specific conductance was measured in groundwater and surface-water at each of the piezometer stations on November 14, 1997 to provide a proxy measure

of salinity. Specific conductance in ground water

ranged from 1,100 to 11,000 μS/cm and was greater in

ground water than in overlying surface water at five of

the seven piezometers (table 10). This range of conductance qualifies the ground water in the piezometers as

slightly brackish to brackish, using the classification of

Stewart and Kantrud (1971). The specific conductance

of seawater at Kii ocean outlet was 52,000 μS/cm (see

fig. 21), so the saltiest ground water was about one-fifth

of seawater salinity.

Specific conductance in ground water generally

was higher at more seaward sites and was high at the

two sites where refusal to driving indicated that hard

rock, probably limestone, was struck (7,100 μS/cm at

station 13 and 11,000 μS/cm at station 17). The lowest

conductance was recorded at the most inland site, station 18 (1,100 μS/cm), and likely reflects infiltration of

pond water that has undergone slight evaporative concentration. Conductances of 5,000 μS/cm at pond D

inland (station 14) and 9,500 μS/cm at Hospital ditch

(station 16) suggest that the limestone aquifer containing brackish water extends inland under these sites. The

limestone aquifer likely extends to some point between

these sites and station 18 at pond F, and at least to the

inland edge of pond D, 375 ft inland of Punamano ditch.

The large difference in conductances between adjacent

stations 15 and 16 (1,800 and 9,500 μS/cm) indicates

that the piezometer at station 15 is just deep enough to

tap a slight mixture of downward-infiltrating water

from pond C (1,000 μS/cm) and the brackish water in

the underlying carbonate aquifer tapped by piezometer

16 (9,500 μS/cm).

Specific conductance values in the ponds can be

explained by slight evaporative concentration of well

water (pond F is closest to the Kii artesian wells, ponds

C and D are farther away and receive some or all of their

water after it passes through pond F). The high conductance of 15,000 μS/cm in pond A (table 10), however,

mainly reflects a management action by USFWS: the

pond had been drained in August for maintenance and

was allowed to refill with brackish outer-ditch water

because well water was in short supply at the time. Specific conductance was lower in Hospital ditch than in

Punamano ditch (1,000 and 2,400 μS/cm).

Ground-Water/Surface-Water Interaction at Kii Unit

Several inferences can be drawn regarding the

relation of ground water to surface water at Kii Unit.

Piezometers at stations 12, 13, 14, 16, and 17 tap an

aquifer containing brackish water and having high

hydraulic diffusivity, most likely consisting of reef

limestone and associated coralline rubble and sand.

Hydraulic diffusivity is the ratio of aquifer transmissivity to aquifer storage coefficient, and high diffusivity

can arise from high transmissivity (or hydraulic conductivity), low storage coefficient (such as from confinement), or a combination of the two factors. Estimates of

hydraulic conductivity in limestone aquifers on Oahu

(from pumping tests and tidal analyses) commonly
Ground-Water/Surface-Water Interaction 49

1 Instantaneous manual measurement

2 Manual measurement, September 17 (not measured on October 7)

3 Station 19 is a monitoring well on land and has no corresponding surface-water measurement

Table 9. Ground-water and surface-water levels at selected stations on September 5, October 7, and December 10,

1997, James Campbell National Wildlife Refuge, Oahu, Hawaii

[Water levels in feet above mean sea level; values are daily mean levels from continuous recorders; at stations 12 through 18, both surface and

ground water were measured; station shown on figures 6, 7, and 8]

Station

Surface-water body,

ground-water body, or

station name

September 5 October 7 December 10

Ground-water piezometers with surface-water standpipes attached

12 pond D 2.8 2.9 3.2

12 ground water 1.2 1.3 0.9

13 Punamano ditch 1.8 1.8 1.8

13 ground water 1.1 1.2 1.0

14 pond D inland -- 2

2.8 13.2

14 ground water -- 2

3.0 13.3

15 pond C 3.7 4.0 4.1

15 ground water 3.1 3.2 3.6

16 Hospital ditch -- 2

1.3 11.8

16 ground water -- 2

2.9 13.2

17 pond A 1.2 1.6 2.9

17 ground water 1.2 1.3 1.0

18 pond F -- 2

3.9 14.1

18 ground water -- 2

4.0 14.2

19 ground water3 -- 1.8 --

Surface-water stations

1 Punamano ditch 2.4 2.5 2.5

3 Kii ditch 3.1 3.1 3.1

4 Kahuku storm drain 2.0 2.0 1.8

5 Hospital ditch 2.0 2.0 2.0

7 Kii outlet duckbill 1.8 1.8 1.8

8 Kii ocean outlet 2.0 2.3 3.0

11 Kii outlet pump 1.8 1.8 1.8

Pond staff gages and recorders

20 Pond A (staff) -- 1

1.6 12.9

21 Pond B (recorder) 3.6 3.6 3.6

22 Pond C (staff) -- 1

4.0 14.1

23 Pond C (staff) at kiosk -- 1

4.0 14.1

24 Pond D (staff) -- 1

2.9 13.2

25 Pond E (gate-in) -- 1

1.9 12.1

27 Pond F (staff) -- 1

4.1 14.1

28 Pond G (staff) -- 1

3.2 13.4

36 Punamano pond (recorder) 2.6 2.9 --
50 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

exceed 10,000 ft/d (Dale, 1974; Williams and Liu,

1975; Khan, 1981; Oberdorfer and Peterson, 1985).

High hydraulic diffusivity is indicated by the presence of large-amplitude tidal fluctuations in piezometers 12, 13, and 17, and the lack of tidal damping over

distances of 1,100 to 2,200 ft from the coast. Piezometers 14 and 16 probably tap this aquifer as well, judging

from their high specific conductances (5,000 and 9,500

μS/cm), although recorders were not placed on these

piezometers and so tidal fluctuations were not confirmed in them.

The limestone aquifer underlying Kii Unit is confined by the overlying silty-clay alluvium and pond-bottom muds. The hydraulic relation of ponds to aquifer

can be described as semiperched, using the nomenclature of Meinzer (1923). That is, water in the ponds

belongs to the same zone of saturation as in the aquifer

(there is no intervening unsaturated zone) but water levels in the ponds are greater than the potentiometric level

in the underlying aquifer because of the intervening

layer of low-permeability mud and clay. The surface of

the pond is the water table and is different than the

potentiometric level in the aquifer.

The subbottom mud-and-clay confining unit

apparently is very effective. A confining unit capable of

fully damping out 2-ft tidal fluctuations over a vertical

distance of only a few feet is sufficiently low in hydraulic conductivity that it will strongly inhibit groundwater/surface-water exchange. To a first approximation, then, it can be reasonably inferred that the ponds

and ditches at Kii Unit are fairly well isolated from

underlying ground water, and tend not to exchange

water to any great degree. This contention is supported

by the distinct differences in specific conductance

between ground water and surface water at most of the

piezometers (table 10).

The greatest potential for ground-water seepage is

in the downward direction, because most pond levels

and ditch levels are higher than ground-water potentiometric levels in the underlying aquifer. This is strictly

true for the period of observation (September 5, 1996

through January 8, 1998), but probably is true of dry

seasons in general at Kii Unit. It is not known if this pattern holds during the wet season or from year to year.

However, the probable high hydraulic conductivity of

the limestone aquifer would tend to preclude potentiometric levels from rising much higher than observed:

water drains to the ocean too readily in such aquifers to

build up much head.

The principal exception to the general pattern of

downward gradients was at station 16 (table 9). At station 16, ground-water levels in October and December

were 1.1 and 1.4 ft higher than the typical Hospital ditch

level of 1.8 ft (the October ditch level of 1.3 ft apparently was measured during a drawdown cycle of the

outlet pump). The piezometer at station 16 is 3.2 ft

deeper than that at station 15, and ground-water levels

at station 16 were consistently lower than at station 15

(0.3 ft lower in October, 0.4 ft in December). Therefore,

ground-water levels at station 16 could reflect head loss

along a curving ground-water flow path running downward from pond C at station 5 and curving laterally and

then upward to discharge into Hospital ditch.

Regional Salinity Survey and Reconnaissance

for Ground-Water Seepage

A reconnaissance survey was done throughout the

coastal plain in the vicinity of the Refuge to measure

specific conductance (a proxy measure of salinity) and

temperature of surface water in ponds and ditches and

to search for signs of ground-water seepage. The survey

was done over 3 days, November 12–14, 1997, under

dry-season conditions. The location of each measurement was determined in the field with a global positioning system (GPS) instrument.

Results of the survey are summarized in table 11

and figures 20 and 21. At locations where stratification

was detected in the water column, two measurements

were recorded: one at the top and one at the bottom of

the water column; the bottom value was shown in

Table 10. Specific conductance in ground-water piezometers

and overlying surface-water bodies at Kii Unit, James

Campbell National Wildlife Refuge, Hawaii, November 14,

1997

[Specific conductance in μS/cm (microsiemens per centimeter); stations

shown in figure 8]

Station Location Ground

water

Surface

water

12 Pond D 2,900 3,600

13 Punamano ditch 7,100 2,400

14 Pond D inland 5,000 3,600

15 Pond C 1,800 1,000

16 Hospital ditch 9,500 1,000

17 Pond A 11,000 15,000

18 Pond F 1,100 700
Ground-Water/Surface-Water Interaction 51

Table 11. Specific conductance and temperature of surface and ground waters on the Kahuku coastal plain in and near James

Campbell National Wildlife Refuge, November 12–14, 1997

[Readings are given for both top and bottom of water column where stratification was detected; μS/cm, microsiemens per centimeter; °C, degrees Celsius; --,

not measured or not applicable; in., inches]

Site

(figs. 20

and 21)

Specific conductance

(μS/cm)

Temperature

(°C)

Top Bottom Top Bottom Remarks

1 2,400 -- 24.0 -- Punamano ditch at west refuge fence; Nov. 12, 1030 hours

2 1,400 1,900 24.6 23.9 Punamano ditch just west of Campbell road crossing; water lilies

3 1,200 1,500 24.4 24.3 Punamano ditch

4 860 -- 24.4 -- Punamano ditch

5 810 -- 24.7 -- Punamano ditch, bend in ditch

6 790 -- 24.9 -- Punamano ditch, end of open water; pickleweed seaward

7 780 -- 24.6 -- Punamano ditch

8 760 -- 24.3 -- Punamano ditch, 12-inch PVC pipeline crossing

9 750 -- 24.7 -- Punamano ditch

10 740 -- 24.7 -- Punamano ditch, limestone fragments in soil; ironwoods seaward

11 730 760 24.9 24.7 Punamano ditch, slough and pickleweed lie seaward; rain 1130 hour

12 720 -- 24.2 -- Punamano ditch near shack, electricity lines run inland; grass in ditch

13 710 -- 25.0 -- Punamano ditch

14 690 -- 24.2 -- Punamano ditch at station 1, downstream of duckbill

15 700 -- 24.0 -- Punamano ditch at station 1, upstream of culvert; rain stops 1150 hours

16 700 -- 24.6 -- Punamano ditch at station 1, upstream of culvert; 1400 hours

17 680 730 24.5 24.6 Punamano ditch

18 670 -- 23.9 -- Punamano ditch; cattails

19 4,600 9,100 27.1 -- Unnamed saline slough seaward of Punamano ditch; pickleweed; shallow,

about 4 inches

20 19,000 -- 26.1 -- Same slough; dead cattails, iron floc on bottom; possibly near margin of

limestone aquifer or tidal influence

21 660 -- 24.1 -- Punamano ditch; back to ditch after detour to slough

22 640 -- 23.9 -- Last site on Punamano ditch; 1520 hours

23 3,000 3,300 24.2 -- Unnamed ditch, east side Nudist Camp road

24 2,200 -- 24.3 -- Unnamed ditch, west side Nudist Camp road

25 900 -- 23.6 -- Punamano north pond at U.S. Fish and Wildlife Service gage; Nov. 13

26 900 -- 23.4 -- Punamano north pond; cattails

27 900 -- 23.6 -- Punamano north pond; christmas berry

28 900 940 23.6 23.5 Punamano north pond; cattails; firm bottom with shells, coral (?)

29 890 -- 23.7 -- Punamano north pond

30 900 -- 23.7 -- Punamano north pond

31 880 -- 23.5 -- Punamano north pond

32 880 -- 23.7 -- Punamano north pond; christmas berry alcove; white clay bottom, sampled

clay

33 900 -- 23.8 -- Punamano north pond

34 900 -- 23.8 -- Punamano north pond

35 890 -- 25.0 -- Punamano south pond, small west part

36 880 -- 25.8 -- Punamano south pond, small west part

37 740 -- 24.8 -- Punamano south pond, crossed over into larger east part

38 720 -- 24.7 -- Punamano south pond, large east part; line of poles, seaward end

39 720 -- 24.8 -- Punamano south pond, large east part; another line of poles, west end

40 720 -- 24.6 -- Punamano south pond, large east part

41 700 740 25.2 -- Punamano south pond, large east part

42 720 -- 25.2 -- Punamano south pond, large east part

43 700 -- 24.1 -- Punamano south pond, large east part

44 720 -- 24.5 -- Punamano south pond, large east part

45 720 -- 25.2 -- Punamano south pond, large east part

46 890 -- 25.8 -- Punamano south pond, back to small west part; another line of poles, east

end

47 880 -- 23.0 -- Punamano Spring finger channel; 1335 hours

48 620 -- 22.6 -- Plum Tree Spring

49 620 -- 22.9 -- Unnamed ditch running inland from Plum Tree Spring

50 580 -- 24.4 -- Same ditch, farther inland; many other ditches around

51 700 -- 30.2 -- Pond F at piezometer 18; Nov. 14

52 1,100 -- 25.7 -- Piezometer 18 ground water

53 740 -- 29.2 -- Pond C, staff gage and gate near kiosk
52 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

54 3,600 -- 26.5 -- Pond D, inland end at piezometer 14

55 5,000 -- 25.1 -- Piezometer 14 ground water

56 3,600 -- 25.6 -- Pond D, seaward end at piezometer 12

57 2,900 -- 25.6 -- Piezometer 12 ground water

58 2,400 -- 26.5 -- Punamano ditch at piezometer 13

59 7,100 -- 26.2 -- Piezometer 13 ground water

60 1,800 -- 26.5 -- Pond G, seaward end at gate to Punamano ditch

61 1,300 -- 26.3 -- Pond G, inland end at flowing pipe from artesian wells

62 660 -- 23.3 -- Pond F inland, in flowstream from pipe flow (well water)

63 680 -- 27.1 -- Pond F inland, 20 ft east of last site

64 730 -- 28.4 -- Pond F seaward, across berm from site 62

65 650 -- 21.9 -- Kii artesian wells sump

66 1,000 -- 27.3 -- Pond C, seaward end

67 2,900 -- 26.6 -- Blind ditch near windmill

68 1,000 -- 27.5 -- Pond C at piezometer 15

69 1,800 -- 25.9 -- Piezometer 15 ground water

70 1,000 -- 26.1 -- Hospital ditch at piezometer 16

71 9,500 -- 25.0 -- Piezometer 16 ground water

72 890 -- 28.8 -- Pond B at staff gage and gate to pond A

73 15,000 -- 28.1 -- Pond A at piezometer 17

74 11,000 -- 28.0 -- Piezometer 17 ground water

75 5,600 -- 26.5 -- Outer ditch, just west across berm from pond A at piezometer 17

76 27,000 -- 28.5 -- Raboy ditch, just north across berm from pond A at piezometer 17

77 5,000 -- 26.9 -- Ocean outlet ditch at station 8

78 9,000 -- 29.6 -- Ocean outlet ditch just upstream of partly damming sand plug

79 52,000 -- 25.8 -- Ocean at ditch outlet; sample seawater at edge of limestone shelf

80 2,500 -- 27.8 -- Station 7, upstream of culvert, Punamano ditch

81 4,700 9,900 26.7 25.4 Station 7, downstream of duckbill, outer ditch

82 4,700 21,000 27.2 26.6 Outer ditch east of pond E seaward gate

83 4,900 -- 27.9 -- Pond E seaward, at gate to outer ditch

84 2,300 -- 27.3 -- Pond E inland, at gate to Punamano ditch

85 5,500 16,000 26.8 26.2 Outer ditch at outer flood-relief swale, station 34

86 1,300 -- 26.3 -- Punamano ditch at outer flood-relief swale, station 34

87 980 -- 27.1 -- Hospital ditch at inner flood-relief swale, station 33

88 1,000 -- 26.3 -- Punamano ditch at inner flood-relief swale, station 33

89 2,900 -- 26.2 -- Blind ditch at inner flood-relief swale, station 33

90 2,900 -- 26.8 -- Blind ditch, halfway to windmill

91 1,500 -- 26.8 -- Punamano ditch, halfway to windmill

92 2,100 -- 27.5 -- Punamano ditch at windmill

93 2,300 -- 27.2 -- Punamano ditch halfway from piezometer 13 to west refuge fence

94 2,400 -- 27.2 -- Punamano ditch at west refuge fence

95 1,100 -- 27.2 -- Hospital ditch at pond C staff gage

96 770 1,300 26.6 26.3 Hospital ditch halfway to refuge fence

97 590 -- 25.2 -- Hospital ditch at refuge fence

98 860 -- 28.9 -- Pond C, inland corner by sewage treatment plant

99 3,500 4,300 26.2 25.3 Kii ditch, seaward end by sewage treatment plant

100 2,200 -- 24.5 -- Kii ditch, halfway to station 3

101 1,400 -- 23.2 -- Kii ditch at station 3, downstream side of checkdam

102 1,400 -- 24.2 -- Kii ditch at station 3, upstream side of checkdam

103 1,200 -- 23.5 -- Kii ditch at Kamehameha Highway bridge

104 470 -- 25.1 -- Hospital ditch at station 5

105 440 -- 27.2 -- Hospital ditch inland of Kamehameha Highway

106 460 -- 24.7 -- Hospital ditch further inland

107 430 -- 21.8 -- Hospital ditch near source; shallow, flowing stream over sand channel

Table 11. Specific conductance and temperature of surface and ground waters on the Kahuku coastal plain in and near James

Campbell National Wildlife Refuge, November 12–14, 1997--Continued

[Readings are given for both top and bottom of water column where stratification was detected; μS/cm, microsiemens per centimeter; °C, degrees Celsius; --,

not measured or not applicable; in., inches]

Site

(figs. 20

and 21)

Specific conductance

(μS/cm)

Temperature

(°C)

Top Bottom Top Bottom Remarks
   



  

Marconi Road

Limit of 

marshy

wetland

Nudist Camp

Road

Marconi Road

KAMEHAMEHA

HIGHWAY

Limit of 

marshy

wetland

Punamano Ditch

Figure 20. Specific conductance of surface-water bodies in and near Punamano Unit, James Campbell National 

Wildlife Refuge, Oahu, Hawaii, November 12-14, 1997.

EXPLANATION

21°42'

157°58'30" 157°58'

21°41'45"

OAHU Pacific

Ocean Area

of map



MARSH (Holocene)

ALLUVIUM (Holocene)

LIMESTONE (Pleistocene)

LITHIFIED DUNE, CALCAREOUS (Pleistocene)

KOOLAU BASALT (Pleistocene and Pliocene)

SAMPLING SITE AND SPECIFIC CONDUCTANCE, IN MICROSIEMENS

PER CENTIMETER AT 25 DEGREES CELSIUS--number in parentheses is

site number

Pls

Pls

Pls

Pls

Pls

Tkb

Tkb

Pls

Pls

Pls

Pls

Pd

Pd

Ra

Ra Ra

Ra

Base from U.S. Geological Survey digital line graph maps, 

Kahuku quadrangle, 1:24,000.

0 500 1,000 FEET

0 100 200 METERS

Ground-Water/Surface-Water Interaction 53
   







 



157°57'38" 157°57'15"

21°44'50"

21°41'28"

Figure 21. Specific conductance of surface-water bodies in and near Kii Unit, James Campbell National Wildlife Refuge, 

Oahu, Hawaii, November 12-14, 1997.

KAMEHAMEHA HIGHWAY

Punamano Ditch

Kii Ditch

Hospital

Ditch

SAMPLING SITE AND SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER AT 25 DEGREES CELSIUS--

number in parentheses is site number

EXPLANATION

OAHU Pacific

Ocean Area

of map

0 500 1,000 FEET

0 100 200 METERS

Base from U.S. Geological Survey digital line graph maps, 

Kahuku quadrangle, 1:24,000 MARSH (Holocene)

BEACH SAND, CALCAREOUS (Holocene)

SAND DUNES, CALCAREOUS (Holocene)ALLUVIUM (Holocene)

LIMESTONE (Pleistocene)



LITHIFIED DUNE, CALCAREOUS (Pleistocene)

Pls

Rd Pd

Rs

Ra

Pls

Pls

Pls

Pls

Pls

Pls

Pls

Pd Pd

Rd

Rd

Rs

Ra

Ra

Ra

Ra

Ra

Ra

Ra

Ra

Ra

Ra

Ra

54 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii
Ground-Water/Surface-Water Interaction 55

figures 20 and 21. For reference, the specific conductance in seawater at Kii ocean outlet (site 79) was

52,000 μS/cm. Takasaki and Valenciano (1969) showed

correlations between specific conductance and chloride

concentration. For water having contacted calcareous

material, a conductance of 600 μS/cm corresponded to

a chloride concentration of 100 mg/L, and 3,000 μS/cm

corresponded to 1,000 mg/L. Chloride concentration in

seawater is about 19,500 mg/L.

Salinity at Punamano Unit

At Punamano Unit (fig. 20), the freshest water

measured was at site 50 (580 μS/cm and 24.4°C), near

the head of a ditch just to the east of Plum Tree Spring.

The coldest water was at Plum Tree Spring at site 48

(22.6°C and 620 μS/cm). Punamano Spring at site 47

measured 880 μS/cm and 23.0°C. The low conductance

and temperature at these sites identifies them as probable Koolau aquifer discharge that has not been much

affected by heating or evaporative concentration. For

comparison, water from the Kii artesian wells (site 65 in

fig. 21), which is known to come from the Koolau aquifer, had a conductance of 650 μS/cm and a temperature

of 21.9°C. Flow at both Punamano and Plum Tree

Springs is not pronounced; flow is discernible if bottom

sediment is disturbed, but it is not readily apparent otherwise.

Conductance is low in Punamano ditch between

Plum Tree Spring and gaging station 1 at Nudist Camp

Road, and between the spring and Punamano south

pond (sites 35 to 46), where conductance is 700 to 740

μS/cm. The Plum Tree Spring area is probably a main

source of water, both to Punamano south pond and to

eastward flowing water in Punamano ditch. That is,

flow from the Plum Tree Spring area may be great

enough that it diverges both left and right where the

ditches leading from the spring intersect Punamano

ditch.

Other ponds at Punamano have conductances of

880 to 940 μS/cm. This could represent evaporative

concentration of fresher water from Plum Tree Spring,

separate sources of water in the ponds themselves, or

mixtures of several water sources. Water in Punamano

north pond (sites 25 to 34) is colder at 23.7°C than the

ponds to the south of it. This could possibly signify a

separate, local source of colder, Koolau-derived discharge; or, it may simply result from evaporative cooling (north pond is the largest pond and is subject to the

longest wind fetch).

Several side ditches in the Punamano area have

much higher conductance than the springs and ponds.

Along Nudist Camp Road, conductances of 3,300 and

2,200 μS/cm were measured in ditches just east and

west of the road, respectively (sites 23 and 24). These

values may reflect evaporative concentration of fresher

water under stagnant conditions, or residual salinity

from the defunct saltwater aquaculture ponds east of the

road.

Seaward of Punamano ditch, near the wishboneshaped ditch, conductances of 9,100 and 19,000 μS/cm

were measured at sites 19 and 20, indicating brackish to

subsaline waters. The area near sites 19 and 20 is a shallow slough with salt-tolerant vegetation and a bottom of

calcareous sand. The pattern of patchy vegetation and

bare sand gave a visual impression of a tidal flat with

varying water level. Dead cattails were noted, as was an

iron floc on the bottom of the slough. Such high values

of conductance this far inland are unusual and may be

due to brackish water from the limestone aquifer that

lies just seaward of these sites.

East of Nudist Camp road, sites 9 through 14 along

Punamano ditch have conductances of 700 to 760

μS/cm, not much different from the fresher waters near

the springs, and perhaps representing slight evaporative

concentration or diffuse ground-water gains along the

ditch. No abrupt contrasts in conductance or temperature were apparent that might indicate a strong pointsource of seepage in this reach.

Salinity at Kii Unit

The freshest water measured in the Kii area (fig.

21) was at site 107 near the headwaters of Hospital ditch

(430 μS/cm and 21.8°C). The flow in Hospital ditch

was not traced all the way to its source, but Koolau

Basalt and limestone and lithified dunes of Pleistocene

age are mapped immediately south of site 107 on Hospital ditch (fig. 17). Flow in Hospital ditch probably is

ground water discharging from the Koolau aquifer,

which is considerably fresher and slightly colder at this

inland location than water from the Kii artesian wells

(650 μS/cm, 21.9°C).

In nearby Kii ditch, conductance increases from

1,200 μS/cm at Kamehameha Highway (site 103) to

4,300 μS/cm at site 99 just 1,000 ft downstream. This

increase in conductance clearly indicates a gain in

stream discharge along this reach, and that the new

source of water has higher specific conductance than
56 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

upstream water. The exact nature of the source is not

clear.

Along Punamano ditch, conductance increases

from 720 to 860 μS/cm from site 11 to the southeast,

until saltier water is encountered at the confluence with

Kii ditch. The conductance of 2,400 μS/cm at the confluence (sites 1 and 94) indicates roughly equal contributions from Punamano and Kii ditches, assuming

mixing of waters having conductances of 760 μS/cm

(site 8) and 4,300 μS/cm (site 99). Within Kii Unit, conductance decreases from 2,400 to 1,000 μS/cm along

Punamano ditch from the west fence (site 94) to the

swale at Hospital ditch (site 88). This decrease probably

reflects progressive blending with Hospital ditch water,

which ranges from 590 to 1,300 μS/cm inside the refuge

fence (sites 87, 95 to 97), and perhaps to seepage or

releases from ponds C or B.

Water in blind ditch (sites 67, 89 to 90) is 2,900

μS/cm, which is higher than in adjacent ditches and may

be a good example of evaporative concentration. This

ditch is stagnant, with no throughflow, and rainfall and

seepage to the ditch are less likely to keep pace with

evaporation than in adjacent ditches, which also receive

surface-water inputs.

Water in the outer ditch is stratified like an estuary

at site 82, with brackish water of 4,700 μS/cm at the top

of the water column and subsaline water of 21,000

μS/cm at the bottom. Water in Raboy ditch (site 76) was

27,000 μS/cm, the highest on-land conductance measured. Water in the outer ditch may reflect seawater

overwash, with fresher water from the inner ditches

floating on top of deeper, subsaline water. The subsaline water in the lower part of the water column in the

outer ditch may reflect ground-water gains as well, or

dilution and incomplete mixing of seawater with discharge from the Kii Ponds. Raboy ditch is shallow,

however, and not stratified. Hence, Raboy ditch might

gain brackish or subsaline ground water by upward

seepage from the shallow limestone aquifer in that

vicinity, with evaporative concentration perhaps further

increasing the salinity (Raboy ditch is nearly stagnant,

and evaporative concentration would be progressive

during dry periods).

Conductance varies substantially among the

ponds, reflecting different water sources and the order

of water routing from pond to pond. The Kii artesian

wells produced water at 650 μS/cm and 21.9°C on the

day of the survey (site 65). This water is fed to the

ponds, some in succession. Ponds B, C, F, and G are fed

directly by piped water from the wells, whereas pond D

is fed from pond F, and pond A is fed from pond B.

Ponds E-inland and E-seaward have water-control

structures that supply them with water from Punamano

ditch and outer ditch, respectively. Pond A also has a

water-control structure to the outer ditch, from which it

was refilled during the fall of 1997 after having been

drained for maintenance in August.

Table 12 summarizes specific conductance readings for the Kii ponds, grouped in rough order of water

routing or water source. Some of the ponds were sampled at more than one location.

Conductances in ponds B, C, and F appear to

reflect slight evaporative concentration of the well

water. Ponds G and D have conductances that are 2 to

5.5 times higher than that of well water. These ponds

presumably have lower flushing rates and longer residence times, allowing additional evaporative concentration. This is particularly reasonable for pond D, which

receives its water from pond F. The higher conductances in ponds G and D probably did not arise from

backflow of brackish Punamano ditch water through the

water-control structures, or from upward seepage of

brackish ground water, because the typical pond levels

of 3 to 4 ft were higher than ditch levels since late January (fig. 11, station 7) and higher than ground-water

levels since early September (fig. 19) or before.

Pond E-inland is fed from Punamano ditch,

whereas pond E-seaward is fed from outer ditch, which

would explain the higher conductance in the seaward

pond. Pond A was refilled from the outer ditch progressively through the fall of 1997 after being drained in

August 1997 for maintenance (M. Silbernagle, USFWS

Haleiwa Office, written commun., 1999), which

explains the high conductance there (the highest of all

the ponds).

Pond A had the thinnest layer of low-permeability

material on the pond bottom and none of the stiff, siltyclay alluvium that was present at other piezometers

(table 8). This thin mud cover could be areally patchy,

allowing upward seepage of brackish ground water

from the underlying limestone aquifer. However,

upward seepage can only occur if there is an upward

gradient (ground-water level greater than surface-water

level). On the basis of daily mean levels (fig. 19), such

a condition was observed only during the first week of
Ground-Water/Surface-Water Interaction 57

observations in September 1997 at station 17, at a time

when pond A remained mostly drained.

Previous Salinity Observations

Takasaki and Valenciano (1969, their fig. 21) conducted a reconnaissance salinity survey in 1963, reporting chloride concentration rather than specific

conductance. Their survey was done when sugarcane

was being grown on the coastal plain and being irrigated

with water from inland wells, many of which produced

brackish water as a result of heavy pumping. The chloride concentrations they reported at sites in the ditches

and marshes equate to specific conductances about 2 to

7 times higher than observed in this study. However,

much has changed in terms of land use, irrigation practices, and ditch management (duckbill valves compared

with flap valves), and the earlier results may have little

relevance to present conditions.

More recently, USFWS has recorded high salinities in the ditches at times when saltwater aquaculture

was prevalent (unpub. data, U.S. Fish and Wildlife Service, Haleiwa, Hawaii). Salinities as high as 14 and 22

parts per thousand (ppt) were recorded just upstream

and downstream of the tidal valve at Punamano ditch

station 1 on January 1, 1994 (the flap valve in place at

the time was known to leak). Similarly, salinity in pond

E has been as high as 22 to 26 ppt when saltwater aquaculture effluent was being discharged to the ditches (M.

Silbernagle, U.S. Fish and Wildlife Service, Haleiwa,

Hawaii, oral commun., 1995). For comparison, the

salinity of seawater at Kii outlet ditch is estimated at

34.2 ppt on the basis of the specific conductance measured there in our survey. The relevance of these earlier

salinity measurements by USFWS is that they may typify conditions that would accompany saltwater aquaculture if similar disposal methods were to be practiced

(disposing saltwater effluents directly to Punamano

ditch).

Potential Migration of Wastewater from the

Kahuku Injection Wells

In the planning stages of this study, there was concern over the possibility that wastewater effluent from

Kahuku sewage treatment plant might migrate to Kii

Unit and affect the surface environment of the Refuge

there. It was known that wastewater from the plant is

disposed of using injection wells, which initially were

thought to be onsite at the treatment plant at Kii Unit.

However, the six wastewater injection wells are

Table 12. Sources of water to ponds at Kii Unit, and specific conductance in the ponds and in the Kii artesian wells,

November 14, 1997, James Campbell National Wildlife Refuge, Hawaii

Pond and source of water

Specific conductance

(μS/cm)

Site

(fig. 21)

Kii artesian wells 650 65

Fed directly from Kii wells:

Pond B 890 72

Pond C-inland 860 98

Pond C-seaward 1,000 66

Pond F-inland 680 63

Pond F-seaward 730 64

Pond G (inland) 1,300 61

Pond G (seaward) 1,800 60

Fed from pond F:

Pond D-inland 3,600 54

Pond D-seaward 3,600 56

Fed from Punamano and outer ditches:

Pond E-inland 2,300 84

Pond E-seaward 4,900 83

Fed from pond B and outer ditch:

Pond A 15,000 73
58 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

actually 0.45 mi away, at the old Kahuku Mill. Wells

4057*01-06 inject the wastewater into confined limestone aquifers and alluvium as shown in figure 17.

Given the distance of the wells from Kii Unit, the confinement of the receiving aquifers at the injection wells,

and the apparent discontinuity of those aquifers

between Kahuku Mill and Kii Unit, it is unlikely that

wastewater effluent can migrate to Kii Unit through

subsurface sedimentary aquifers. It is even less likely

that wastewater effluent can migrate to the Kii artesian

wells, given the buoyancy of domestic wastewater in a

saltwater environment within the limestone aquifers,

and the fact that the Kii wells tap the underlying Koolau

aquifer, which is confined and has an artesian head of

about 12 ft that drives prevailing upward flow into the

overlying sediments.

WATER BUDGETS FOR THE PUNAMANO

AND KII UNITS

Water budgets were computed for ponds and wetlands at Punamano Unit and for ponds at Kii Unit to

examine the balance between water sources and consumptive uses. The budgets were computed monthly for

calendar year 1997 and summed to provide budget

results for the entire year. A diagram showing the terms

used in the water budgets for the Refuge is shown in figure 22.

At Punamano Unit the budget was computed for

the entire marsh complex, including the open-water

ponds and surrounding vegetated wetlands covering

27.5 acres (fig. 2 and table 13). At Kii Unit the water

budget of the ponds that receive inflow from the Kii

artesian wells is of most interest, and so pond E and the

intervening ditches, berms, and incidental patches of

wetlands were omitted from the budget, leaving a budget area of 65.7 acres (fig. 3 and table 13).

Water-Budget Equations

A water budget should ideally account for the principal hydrologic inflows and outflows in the area of

interest. In such a situation, net inflow should equal net

outflow, plus the changes in storage in the area:

Inflow = Outflow + ∆Storage (2)

By expanding with terms appropriate to the Refuge this

becomes:

Rain + SWin + GWin + Wells = ET + SWout + GWout +

∆Storage (3)

where:

Rain = direct rainfall (precipitation) over the budget

area;

SWin = surface-water inflow to the area;

GWin = ground-water inflow to the area;

Wells = ground-water supplied by the Kii artesian

wells (Kii Unit only);

ET = evapotranspiration from the area (the

combination of direct evaporation and

transpiration by plants);

SWout = surface-water outflow from the area;

GWout = ground-water outflow from the area;

∆Storage = change in the amount of water stored within

the area.

Practically, however, some hydrologic components are impossible to measure or can be considered

insignificant, and are omitted to derive simplified budget equations. In this case, inflow is unlikely to equal

outflow plus change in storage. The net water budget

that results includes a residual term that in theory is

equal to the net total of all the unmeasured terms, plus

any errors or inaccuracies in the budget:

Inflow = Outflow + ∆Storage + Residual (4)

Equation 4 can be rearranged to give a slightly different

perspective:

Inflow − Outflow − ∆Storage = Residual (5)

Punamano marsh receives direct rainfall and

surface-water runoff from the uplands and surrounding

land, evaporates and transpires water, discharges surface water through Punamano ditch (measured at station

1), and may gain or lose ground water. The groundwater terms cannot be estimated independently and so

are included in the residual, resulting in this simplified

water-budget equation for Punamano Unit:

Rain + SWin = ET + SWout + ∆Storage + Residual (6)

where the Residual contains GWin and GWout, as well

as any budget inaccuracies.
Berm Berm Storage Evapotranspiration Pond

Rainfall Surface-water inflow

Ground-water

inflow

Surface-water outflow

Ground-water

outflow

Ground-water

inflow

Ground-water

inflow/outflow

Ditch

Artesian well flow

Storage

EXPLANATION

DIRECTION OF GROUND-WATER FLOW AND 

OTHER HYDROLOGIC FLUXES (large magnitude)

DIRECTION OF GROUND-WATER FLOW

(small magnitude)

POND WATER LEVELCHANGE IN POND STORAGE CORRESPONDING 

TO CHANGE IN WATER LEVEL

Figure 22. Terms in the water budgets for Punamano and Kii Units, James Campbell National Wildlife Refuge, Oahu, Hawaii.

Water Budgets for the Punamano and Kii Units 59
60 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

The Kii Unit ponds (minus pond E) receive direct

rainfall and inflow from the Kii artesian wells, evaporate and transpire water, and may gain or lose ground

water. To a first approximation, the Kii ponds are an

isolated hydrologic system, and surface-water inflow

and outflow are thought to be negligible for the ponds.

Water-control structures connect several of the Kii

ponds to adjacent ditches, but flashboards in the controls are usually positioned high enough so that little or

no ditch water enters the ponds. Small amounts of water

may flow out of the ponds over the flashboards, but

USFWS Refuge managers attempt to minimize this

loss. Therefore, the ground-water terms and any unmeasured surface-water flows are included in the residual to

give the following simplified water-budget equation for

Kii Unit:

Rain + Wells = ET + ∆Storage + Residual (7)

where the Residual contains GWin, GWout, SWin,

SWout, and any budget inaccuracies.

Required Data

Monthly measurements of rainfall and potential

evaporation (PE) are listed in table 14. A "composite

full-month rainfall" total for each month was derived by

using data from meteorology station 10 as a base, and

supplementing with data from USFWS meteorology

station 35 where data were missing at station 10. Potential evaporation was computed using the Penman

method (Penman, 1948) and various meteorologic variables recorded during the study (T.W. Giambelluca and

M.A. Nullet, University of Hawaii, written commun.,

1998). "Full-month PE" denotes values that were

adjusted by simple pro-rating to account for missing

days of data. Missing values of PE for November and

December 1996 were estimated as the average of values

in prior and subsequent years for the respective months.

The monthly values of rainfall and potential evaporation measured at Kii Unit were applied at both the

Punamano and Kii Units, assuming that evapotranspiration (ET) is equal to the full monthly amount of potential evaporation (PE). This assumption is reasonable for

the ponds and wetlands of the Refuge, where evapotranspiration is unlikely to be limited by available water

(that is, the open-water ponds and scattered areas of

marsh plants present unlimited "evaporation opportunity").

At Punamano Unit, station 1 discharge values in

table 4 constituted the surface-water outflows, and surface-water inflows from the inland watershed that is

tributary to Punamano Unit (area 1b in table 1 and fig.

5) were estimated from station 1 discharge values by

area-weighted pro-rating.

At Kii Unit, a main component of the budget is

inflow from the Kii artesian wells. Monthly values of

ground-water flow from the wells, recorded by totalizing flow meters, were obtained from USFWS (M. Silbernagle, USFWS Haleiwa Office, written commun.,

1998). Some pro-rating was applied across month

boundaries to adjust values for which meter readings

had been taken in mid-month.

Table 13. Surface areas of ponds and wetlands, James

Campbell National Wildlife Refuge, Hawaii

[Areas were determined by geographic information system (GIS), using

pond and wetland outlines defined on aerial photographs and registered to

digital topographic maps provided by the U.S. Army Corps of Engineers;

ponds shown on figures 2 and 3]

Pond or wetland Surface area

(acre)

Punamano Unit

North pond 5.6

West pond large 0.4

West pond medium 0.2

West pond small 0.1

South pond large 3.6

South pond small 0.5

Spring pond 1.4

Wetland, not including ponds 15.7

Punamano ponds total 11.8

Ponds and wetlands total 27.5

Kii Unit

Pond A 21.1

Pond B 9.3

Pond C 14.3

Pond D 5.8

Pond E-seaward 1.9

Pond E-inland 6.3

Pond F-seaward 2.6

Pond F-inland 3.7

Pond G 8.9

Kii ponds total 73.9

Kii ponds minus ponds E 65.7

Kii fenced area 116.0
Water Budgets for the Punamano and Kii Units 61

1 U.S. Fish and Wildlife Service meteorology station 2 University of Hawaii meteorology station 3 Number of days with records of rainfall or PE at station 10 for months having missing data 4 A composite record using station 10 as the primary gage and substituting station 35 data where station 10 had missing data and less rain than station 35 5 Computed by assigning the average observed daily rate for each month to missing days in that month 6 Missing PE for November and December 1996 estimated by averaging values for the same months in 1995 and 1997

Table 14. Monthly rainfall in the Kahuku uplands, and rainfall and potential evaporation at the Kii Unit of James Campbell

National Wildlife Refuge, Oahu, Hawaii, 1995–97

[Values in inches; PE, potential evaporation; --, not available or not applicable; computed by the Penman method; USFWS, U.S. Fish and Wildlfe]

Upland Kii Unit

Month Station 9

rain gage

Station 35

USFWS

rain gage1

Station 10

rain gage2

Station 10

number of

days with

rain record3

Station 10

PE

Station 10

number

of days with

PE record3

Composite

full-month

rainfall4

Full-month

PE5

1995

January -- 0.92 -- -- -- -- 0.92 --

February -- 3.63 -- -- -- -- 3.63 --

March -- 3.69 -- -- -- -- 3.69 --

April -- 4.09 -- -- -- -- 4.09 --

May -- 0.81 0.31 22 5.73 22 0.81 8.07

June -- 1.14 1.14 -- 7.29 -- 1.14 7.29

July -- 1.63 1.56 -- 7.71 -- 1.56 7.71

August -- 2.05 1.74 -- 7.37 29 1.74 7.88

September -- 2.22 1.89 -- 2.04 10 1.89 6.12

October -- 2.14 3.17 -- 3.42 18 3.17 5.89

November -- 1.40 6.28 -- 3.85 -- 6.28 3.85

December -- 0.47 4.41 -- 3.67 -- 4.41 3.67

1995 total -- 24.19 -- -- -- -- 33.33 --

1996

January -- 8.88 6.96 -- 4.09 -- 6.96 4.09

February -- 2.42 1.07 26 4.99 -- 2.42 4.99

March -- 4.59 0.28 21 6.21 -- 4.59 6.21

April -- 1.08 1.19 -- 6.56 -- 1.19 6.56

May -- 0.61 0.48 29 6.39 29 0.61 6.83

June -- 4.15 3.70 -- 4.59 19 3.70 7.25

July -- 1.98 1.54 -- 4.78 21 1.54 7.06

August -- 1.94 1.93 -- 7.15 -- 1.93 7.15

September -- 3.34 3.25 -- 5.83 -- 3.25 5.83

October -- 1.47 1.59 28 5.92 28 1.59 6.55

November 22.1 15.33 0.00 1 0.14 1 15.33 6

4.54

December 6.8 5.26 -- 0 -- 0 5.26 6

4.25

1996 total 29.6 51.05 -- -- -- -- 48.37 70.44

1997

January 12.0 8.01 4.39 18 2.80 18 8.01 4.82

February 2.6 1.35 1.09 -- 4.33 23 1.09 5.27

March 7.7 4.46 4.82 -- 5.94 -- 4.82 5.94

April 5.3 2.78 3.08 -- 7.11 -- 3.08 7.11

May 6.7 0.77 3.28 -- 7.21 -- 3.28 7.21

June 3.5 2.42 2.09 -- 8.56 -- 2.09 8.56

July 2.8 1.52 1.43 -- 8.91 -- 1.43 8.91

August 1.5 0.33 0.37 -- 8.55 -- 0.37 8.55

September 2.7 1.78 1.42 -- 7.79 -- 1.42 7.79

October 5.4 2.12 2.02 -- 6.72 -- 2.02 6.72

November 3.5 1.67 2.12 -- 4.89 28 2.12 5.24

December 3.9 4.63 1.75 -- 3.43 22 1.75 4.83

1997 total 56.9 31.84 27.86 -- 76.24 -- 31.48 80.95

November 1996–

October 1997 total 78.7 46.13 -- -- -- -- 48.20 78.80
62 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

At both units, changes in storage were computed

using end-of-month water levels derived from USFWS

readings at pond staff gages and data from water-level

recorders operated by USFWS and USGS (table 15). In

cases where measurements were not made on the ending day of the month, values were interpolated from the

closest prior and subsequent dates.

Results of the Water Budgets

Monthly water budgets for calendar year 1997 are

shown in table 16 for Punamano Unit ponds and wetlands and in table 17 for Kii Unit ponds.

At Punamano Unit, the atmospheric components

(rainfall and evapotranspiration) were the dominant

measured terms in the budget in most months and

showed a large excess of evapotranspiration over rainfall (table 16). Only in January did rainfall exceed

evapotranspiration. As a result, the inflow-minusoutflow subtotal was predominantly negative throughout the year and showed a strong seasonal cycle, with

the largest negative values during the summer months.

Subtracting the change-in-storage term (∆Storage), the

resulting values of the residual differ somewhat from

the inflow-minus-outflow values, but the overall pattern

of negative values persisted for much of the year,

implying that large gains from ground water were necessary to keep up with the demands of evapotranspiration and maintain standing water in the marsh. The

change-in-storage term was large in February, March,

and April, reflecting the effects of storms. The residual

during these months is more likely to include errors in

the surface-water terms, making it difficult to interpret

the residual strictly in terms of ground-water gains or

losses.

On an annual basis at Punamano Unit, total inflow

was 24.8 Mgal, total outflow was 66.3 Mgal, and the

residual showed a -37.9 Mgal deficit. An annual gain

from ground water equalling a water depth of 50.8

inches over the budget area is required to satisfy this

deficit. Supporting evidence for such ground-water gain

lies in the low specific conductance readings throughout

the Punamano ponds, which are just slightly higher than

the springs that feed them (table 11 and fig. 20), and in

the relatively stable water level in Punamano north

pond (table 15). These data verify that the natural supply of freshwater is adequate to keep pace with evapotranspiration and maintain low salinity and stable pond

level.

At Kii Unit, evapotranspiration and inflow from

the artesian wells were the largest terms in most months

1 Rising water levels in pond A from September through December corresponded with USFWS filling of pond A with water from the adjacent outer ditch.

Table 15. End-of-month water levels in ponds at James Campbell National Wildlife Refuge, Oahu, Hawaii, December 1996

through December 1997

[Values in feet. Data from USFWS measurements at pond staff gages and from water-level recorders operated by USFWS and USGS; where measurements

were not made on the ending day of the month, values were interpolated from the closest prior and subsequent dates]

Month

Kii ponds Punamano

ABCDEFG north pond

December 1996 2.52 3.94 4.45 3.27 1.94 4.31 3.75 3.03

January 1997 2.73 3.98 4.46 3.26 3.08 4.35 3.75 2.98

February 2.14 3.99 4.33 3.25 1.74 4.26 3.71 2.07

March 2.20 3.90 4.35 3.24 1.70 4.30 3.70 2.54

April 1.95 3.93 4.21 3.25 1.34 4.23 3.66 2.29

May 1.86 3.92 4.20 3.26 1.08 4.22 3.66 2.33

June 1.60 3.82 4.08 3.24 0.90 4.18 3.60 2.42

July 1.60 3.68 3.90 3.10 0.92 4.10 3.40 2.57

August 1.18 3.70 3.76 2.89 1.03 3.97 3.14 2.60

September 1

1.57 3.60 3.83 2.86 1.75 4.07 3.12 2.68

October 1

2.15 3.85 3.82 3.08 1.29 4.11 3.54 2.61

November 1

2.71 3.69 4.17 3.24 1.51 4.17 3.50 2.61

December 1

2.94 3.63 4.19 3.25 3.05 4.21 3.61 2.62

Change during 1997 +0.42 -0.31 -0.26 -0.02 +1.11 -0.10 -0.14 -0.41
Water Budgets for the Punamano and Kii Units 63

1 Computed by multiplying the composite rainfall or full-month potential evaporation values from table 14 times the budget area

2 Runoff from Punamano inland drainage area (1a in figure 5), estimated from station 1 discharge by area-weighted prorating

3 Station 1 discharge from table 4

4 Computed by applying differences in end-of-month water levels at Punamano north pond in table 15 to the budget area

1 Computed by multiplying the composite rainfall or full-month potential evaporation values from table 14 times the budget area

2 Artesian flow from the Kii wells, metered by USFWS and pro-rated across months where meter readings did not coincide with the ending day of the

month) 3 Sum of changes in individual ponds, which were computed from end-of-month water levels (table 15) and pond areas (table 13)

4 Computed assuming no change in storage in pond A from September through December, when rising water levels corresponded with USFWS filling of

pond A with water from the adjacent outer ditch. The assumption of zero change in storage in pond A eliminates this known, but unmeasured,

surface-water component from the budget

Table 16. Monthly water budget for the Punamano Unit, James Campbell National Wildlife Refuge, Oahu, Hawaii, 1997

[Values in million gallons (Mgal) except where noted; Mgal/d, million gallons per day; the budget area covers 27.5 acres of ponds and wetlands shown in

figure 2; e, estimated]

Inflow Outflow Inflow

minus

outflow

Change in

storage4 Month Rainfall Residual 1 Streaminflow2 Total

Stream

outflow3 Evapotranspiration1 Total

January 6.0 e0.4 6.4 2.0 3.6 5.6 0.8 -0.4 1.2

February 0.8 e0.1 0.9 0.5 3.9 4.4 -3.5 -8.2 4.7

March 3.6 e0.4 4.0 2.0 4.4 6.4 -2.4 4.2 -6.6

April 2.3 e0.2 2.5 1.0 5.3 6.3 -3.8 -2.2 -1.6

May 2.4 e0.1 2.5 0.4 5.4 5.8 -3.3 0.4 -3.7

June 1.6 e0.0 1.6 0.0 6.4 6.4 -4.8 0.8 -5.6

July 1.1 e0.0 1.1 0.0 6.7 6.7 -5.6 1.3 -6.9

August 0.3 e0.0 0.3 0.0 6.4 6.4 -6.1 0.3 -6.4

September 1.1 e0.0 1.1 0.0 5.8 5.8 -4.7 0.7 -5.4

October 1.5 e0.0 1.5 0.0 5.0 5.0 -3.5 -0.6 -2.9

November 1.6 e0.0 1.6 0.0 3.9 3.9 -2.3 0.0 -2.3

December 1.3 e0.0 1.3 0.0 3.6 3.6 -2.3 0.1 -2.4

Total 23.6 1.2 24.8 5.9 60.4 66.3 -41.5 -3.6 -37.9

Annual average

Mgal/d 0.065 0.003 0.068 0.016 0.165 0.182 -0.114 -0.010 -0.104

Inches 31.6 1.6 33.2 7.9 80.9 88.8 -55.6 -4.8 -50.8

Table 17. Monthly water budget for the Kii Uni, James Campbell National Wildlife Refuge, Oahu, Hawaii, 1997

[Values in millions of gallons except where noted; Mgal/d, million gallons per day; the budget area covers 65.7 acres of ponds that are supplied with

artesian well water (ponds A through G, excluding pond E; figure 3]

Inflow Outflow Inflow

minus

outflow

Change in

storage3 Month Rainfall Residual 1 Well water2 Total

Evapotranspiration1

January 14.3 12.2 26.5 8.6 17.9 1.6 16.3

February 1.9 11.5 13.4 9.4 4.0 -5.0 9.0

March 8.6 9.5 18.1 10.6 7.5 0.3 7.2

April 5.5 9.7 15.2 12.7 2.5 -2.5 5.0

May 5.9 10.2 16.1 12.9 3.2 -0.6 3.8

June 3.7 9.4 13.1 15.3 -2.2 -3.0 0.8

July 2.6 9.8 12.4 15.9 -3.5 -2.3 -1.2

August 0.7 9.7 10.4 15.3 -4.9 -5.0 0.1

September 2.5 9.4 11.9 13.9 -2.0 4

0.0 4-2.0

October 3.6 9.8 13.4 12.0 1.4 4

2.5 4-1.1

November 3.8 9.5 13.3 9.3 4.0 4

1.4 42.6

December 3.1 8.2 11.3 8.6 2.7 4

0.3 42.4

Total 56.2 118.9 175.1 144.5 30.6 12.3 42.9

Annual average

Mgal/d 0.154 0.326 0.480 0.396 0.084 0.034 0.118

Inches 31.5 66.6 98.1 81.0 17.2 6.9 24.0
64 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

and rainfall was subordinate, except in January (table

17). In contrast to the Punamano Unit, the inflowminus-outflow subtotal and the residual at Kii Unit

showed large positive values in most months, indicating

a surplus of inflow over outflow and requiring

unaccounted-for losses by surface-water outflow and/or

ground-water seepage. The dry summer months showed

deficits in supply, denoted by the negative values of

inflow-minus-outflow and change in storage. These

values reflect the fact that rainfall and well supply did

not keep pace with evapotranspiration during the summer. When changes in storage are accounted for, the

residual for the summer months is not as strongly negative as the inflow-outflow term. The change-in-storage

and residual terms are complicated somewhat by maintenance at the ponds from mid- to late-1997: the large

negative value of change in storage in August was due

mainly to the draining of pond A (the largest of the

ponds), and refilling of pond A with outer ditch water

from September through December further complicates

the picture. The changes in storage associated with the

refilling were left out of the change in storage term

because the outer ditch water is a separate source of supply from the artesian wells and was not gaged.

On an annual basis at Kii Unit, total inflow was

175.1 Mgal, total outflow was 144.5 Mgal, and the

residual showed a 42.9 Mgal surplus. The surplus represents an annual excess of inflow over outflow equalling 24.0 inches over the budget area, or 118,000 gal/d,

which is equivalent to 36 percent of the average daily

inflow from the artesian wells. The apparent surplus is

strictly hydrologic, and is not a surplus in a management sense. That is, it is not a surplus that can be stored

or used to supply the Refuge, but instead reflects losses

from the system that render this amount of water

unavailable for use. USFWS refuge managers state that

there is not enough water to manipulate levels in the

ponds for management purposes during most of the

year, particularly during the driest months (M. Silbernagle, U.S. Fish and Wildlife Haleiwa, Hawaii, written

commun., 1999). This contention is supported by the

seasonal deficits shown in the budget, and may be true

in other months despite apparent hydrologic surpluses

in the budget.

The large apparent monthly and annual surpluses

in supply at Kii Unit likely indicate unmeasured losses

from the system. Two types of loss are most plausible:

(1) surface-water loss by unmeasured tailwater discharge to the ditches through pond water-control

structures; and (2) ground-water loss by downward

and/or lateral seepage. Slight overflow at flashboards

was observed at ponds D and G at Punamano ditch on

several occasions in fair weather. How prevalent this

overflow is or how much it might amount to is not

known, but the largest overflows probably are during

wet-season rainstorms. Refuge managers state that they

try to maintain pond levels 1 to 2 inches below the flashboards (M. Silbernagle, USFWS Haleiwa Office, written commun., 1999). If pre-storm pond levels are this

close to the tops of the flashboards, then several inches

of rain on a single day could result in large unmeasured

losses through the control structures. If this were to happen numerous times during the year, it might explain a

substantial part of the apparent surplus in the Kii budget. Ground-water seepage losses are plausible given

the downward head gradients observed at most of the

piezometers, and given that pond levels are almost

always higher than adjacent ditch levels. Despite the

mud and clay composition of the pond bottoms and

berms, the entire annual surplus of 24.0 inches over the

area of the ponds could be disposed of at a seepage rate

of only 0.07 in/d. Seepage this small would be difficult

to measure using hydraulic approaches. Alternatives

such as isotopic or other chemical analysis of pond

waters and underlying ground water might be required

to help verify and quantify such seepage.

A final possibility is that the residual components

in the Punamano and Kii budgets result in part (or

largely) from errors and imprecision in the measured or

estimated budget components. The annual residual at

Punamano Unit represents 42 percent of the total budget

and at Kii Unit it represents 13 percent. At Punamano

Unit, the surface-water inflow component was estimated, and therefore is uncertain. Furthermore, there

may be additional surface-water inflows from lowlands

surrounding Punamano marsh that were not accounted

for. At Kii Unit, inflow from the artesian wells was

recorded by totalizing flow meters, but the yield from

each of the three wells was unequal, and there was some

concern in 1998 as to whether all of the meters were

functioning properly. Finally, errors in the rainfall and

evapotranspiration measurements are possible,

although the measurements were made using standard

methods. Some error may have been introduced in estimating full-month values for months with several days

of missing record.
Water and Sediment Quality 65

Relation of the Budget Period to Long-Term

Average Conditions

The 1997 rainfall of 31.48 inches (table 14) is considerably less than the long-term median annual rainfall

(39.0 inches) and mean annual rainfall (41.5 inches) at

nearby Kahuku Mill, equalling 81 percent and 76 percent of these values, respectively (Giambelluca and others, 1986; adjusted values for the long-term base period

1916–83 at Station 912.00). The annual potential evaporation of 80.95 inches for 1997 (table 14) is about the

same as the 82.2 inches of mean annual pan evaporation

reported for the coastal plain by Ekern and Chang

(1985) for the period 1960–65, but a pan factor must be

applied to pan evaporation values to approximate potential evaporation from open water bodies such as ponds

or lakes. Applying the 0.8 factor recommended by

Ekern and Chang (1985) for Hawaii results in a corresponding potential evaporation estimate of 65.8 inches.

However, the 6-year time period of the pan evaporation

data was wetter than normal and not entirely representative of long-term conditions (mean rainfall for 1960–

65 was 49.1 inches, or 118 percent of the 41.5-inch

long-term mean).

Judging from the comparisons above, 1997 was

considerably drier than normal, about 24 percent below

the long-term mean. A dry year would also be expected

to be less cloudy than normal, which would help

account for the measured 1997 potential evaporation

being much greater than the estimate derived from

Ekern and Chang’s (1985) pan evaporation data, which

was measured during a wetter-than-normal period.

WATER AND SEDIMENT QUALITY

An appraisal of water quality within the Refuge

was undertaken as part of this study. Its objectives were

to evaluate current conditions in the Refuge, to determine if any aspects of water quality within the Refuge

pose a threat to wildlife health, and to create a baseline

set of data for possible comparison with future surveys.

Samples of water and pond-bottom sediment were

collected during two surveys, November–December

1994 and March 1997, representing dry- and

wet-season conditions, respectively. Samples were

analyzed for a suite of inorganic and organic chemical

constituents and physical characteristics. The 1994 survey consisted of water samples from five sites and sediment samples from three sites (table 3 and fig. 6). The

1997 survey consisted of water samples from nine sites

of which five were sampled during the 1994 survey.

Water and Sediment Sampling and Analysis

Water samples and pond-bottom sediments were

collected from selected sites (figs. 6 through 9) for

determining major constituents and a suite of trace substances (metals and organic compounds). Although

definitions of the terms "major" and "trace" in reference

to element concentrations are not precise, substances

typically occurring in concentrations of less than 1,000

parts per million (less than 0.1 percent) are considered

trace elements (Forstner and Willmann, 1979, p. 5).

Elements typically occurring in concentrations of

greater than 1,000 parts per million (ppm) are considered major elements.

Ultra-clean procedures (Horowitz and others,

1994) were used for collecting samples for inorganic

analysis. Water samples from the Kii artesian wells

were collected from the common well sump, using precleaned Teflon bailers and with the wells actively flowing. Samples from the ponds were collected by dipping

pre-cleaned high-density propylene 1-liter wide mouth

bottles. Field measurements (temperature, specific conductance, pH, and dissolved oxygen) were made on the

water samples, following standard USGS procedures

(Wilde and others, 1998). Pond-bottom sediments were

cored at selected sites (fig. 9) for mineralogic analysis

and determination of inorganic and organic constituents

as described by De Carlo and Spencer (1995). Where

coring proved difficult, surface sediment was collected

by scooping with a clean mason jar. All samples were

stored on ice prior to analysis, and were shipped to the

USGS National Water Quality Laboratory (NWQL) in

Denver and the Department of Oceanography atomic

spectroscopy facility at the University of Hawaii (UH)

in Honolulu.

Inorganic analyses were made at the UH lab. Analysis of nutrients and organic constituents including

pesticides and VOC's (volatile organic compounds) was

made at the NWQL. The Quality Assurance and Quality

Control (QA/QC) plan for the NWQL laboratory is

described in Pritt and Raese (1995), whereas the

QA/QC plan for the UH laboratory is available upon

request (E.H. De Carlo, University of Hawaii, oral commun., 1997). The performance of each laboratory is
66 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

monitored by semiannual participation in the USGS

Standard Water Reference Sample Program.

Results

Inorganic Chemical Analysis

Results of inorganic analyses of sediments and

water samples are given in tables 18 through 20. Quality

assurance included analysis of a variety of quality control samples. For sediment the National Research Council of Canada standard reference sediment MESS-1 was

analyzed concurrently with environmental samples to

ascertain recovery of sample during sediment digestion

procedures and the subsequent analysis. Observed concentrations generally agree well with certified values

except for a high recovery of the trace element cobalt

that is attributed to the combination of substantial background signal and a very low concentration of cobalt in

this standard (table 18).

Duplicate water samples were collected to evaluate

field variability and analytical reproducibility of analyses. Water samples E and J are duplicates from the composite Kii wells (tables 19 and 20). Major ion and

alkalinity data for the duplicates are highly reproducible. Trace-element data show slightly more variability,

especially for concentrations below 0.1 μg/L and

approach instrument detection limits.

Inorganic Water Chemistry

No large variations in water major ion composition

were noted between the 1994 (dry-season) and 1997

(wet-season) surveys (table 19), except for the calcium

and alkalinity values in pond C. The nearly two-fold

lower calcium and proportional decrease in alkalinity,

but much less variable magnesium, sodium, and potassium concentrations between the two surveys may be

attributable to precipitation of calcium carbonate within

pond C.

The major ion composition of the Kii pond D

(sample D in table 18) is best characterized as slightly

brackish with a chloride concentration about 2 percent

that of seawater. Concentrations of calcium, magnesium, sodium, potassium, chloride, and sulfate, the primary ions in seawater, are about 2 to 5 times higher in

pond D than in water from the Kii artesian wells (samples E and J in table 19). The same element concentrations in Kii pond C (sample C in table 18) are

comparable to or only slightly higher than those in the

well water. Alkalinity is also about three-fold higher in

pond D than in pond C or the wells. Concentrations of

potassium and sulfate in pond D are nearly ten times

higher than in pond C.

The major ion composition of Punamano pond

(sample B in table 19) is roughly intermediate between

that of pond C and pond D. Water in Punamano pond is

only slightly saltier than that in Punamano Spring which

ostensibly feeds it. The dissolved oxygen content of the

pond water is rather low (45 percent saturation). Similarly low oxygen contents were observed in the 1997

(wet-season) samples collected from Kii ditch, from

two sites on Hospital ditch, and from Punamano ditch at

Nudist Camp Road (samples F, G, H, and I in table 19,

respectively). Abundant algal mats and water hyacinth

plants were observed at each of these sites.

The pH of all water ranges from a low of 6.95 in

samples A and E to a high of 8.15 in sample D. The

ponds having pH values in excess of 8 also exhibit

higher calcium, magnesium, and alkalinity values than

waters with lower pH.

Trace-element concentrations in waters (table 20)

are generally low and in a range comparable to that

reported for selected heavy metals in unimpacted or

low-impact areas of Manoa Stream in the Ala Wai

Canal Watershed on Oahu (De Carlo and others, 1997).

Both dissolved (filtered) and total (unfiltered) concentrations of copper fall within the range of 0.4 to 8.2 μg/L

compared with 0.1 to 7 μg/L for water from Manoa

Stream. Zinc concentrations are between 0.5 and 8.9

μg/L. The high value of 8.9 μg/L observed in the filtered aliquot of pond D is approximately five-fold

higher than observed in the unfiltered sample, suggesting a possible contamination of this sample during handling and processing. Elements such as aluminum, iron,

and zinc typically display a high propensity for contamination of samples, owing to their high natural abundance in earth materials, their extensive use in

domestic/industrial materials, and their ubiquitous presence in laboratory environments. Nonetheless, all zinc

concentrations are well within the range observed in

Manoa Stream (0.3 to 15 μg/L) by De Carlo and others

(1997). All cadmium concentrations were less than 0.2

μg/L, in agreement with data for other freshwater samples collected on Oahu. Concentrations of lead ranged

from 0.06 to 0.56 μg/L in samples collected in 1997.

Higher values observed in the 1994 samples, particularly the 7 μg/L measured in the filtered aliquot of
Water and Sediment Quality 67

sample A (Punamano Spring) and the 9 μg/L in the

unfiltered aliquot of sample C (Kii pond C) appear

anomalously high, although they are close to the high

end of the range reported for Manoa Stream (0.01 to

3 μg/L).

Concentrations of other trace elements presented

in table 19 do not appear to display significant trends,

except possibly arsenic, whose concentrations

increased uniformly between the 1994 (dry-season) and

1997 (wet-season) surveys. A possible source of this

element is fertilizers (association of arsenate with phosphate) or pesticides (for example, monomethyl arsenate). The occurrence of the highest concentrations of

arsenic in samples G and H, collected within the Hospital ditch, suggests an input of this element from outside

the Refuge. However, pond D also displayed elevated

arsenic concentrations during both samplings (21 to

30.6 μg/L in filtered and unfiltered aliquots) whereas

pond C did not (1.6 to 2.7 μg/L).

No significant contamination by heavy metals or

other potentially toxic trace elements is apparent from

the data in table 20, except as noted above for arsenic.

Enhanced concentrations of iron and manganese

observed in unfiltered water samples simply reflect

inclusion of soil particles in the unfiltered water.

Inorganic Sediment Chemistry

The major element composition of the sediments

(table 18) is consistent with the mineralogy described

below. Sediment from Kii ponds C and D contain high

concentrations of iron (11 to 12 percent), aluminum (8

to 9 percent), and silicate (13 to 18 percent) that are

characteristic of local soils which contain red clay

derived from weathering of volcanic minerals (De Carlo

and Spencer, 1995). Ponds C and D differ significantly

in their calcium and strontium contents, reflecting the

presence of more marine minerals such as calcite (calcium carbonate) in pond D sediments. Other differences

between the two ponds include higher concentrations of

manganese in sediment from pond D, possibly resulting

from redox reactions associated with the oxidation of

organic matter. Higher concentration of solid phase

manganese in surface sediments than in deep sediments

Table 18. Major-element and trace-element composition of pond-bottom sediments, James Campbell National Wildlife Refuge,

Hawaii, December 28, 1994 (dry season)

[Elements are listed by their chemical symbols; Bottom replicate, replicate sample from bottom of core; MESS-1 Found, determination run on National

Research Council of Canada standard reference sediment designated MESS-1; MESS-1 Certif., certified value for MESS-1]

Sample designation, station number, and location

H, 44, Kii pond C I, 12, Kii pond D F and G, 36, Punamano pond

Element Top Bottom Top Bottom Bottom

replicate Top Bottom Bottomreplicate

MESS 1

Found

MESS 1

Certif.

Major elements (in weight-percent)

Fe 11.2 11.6 11.9 12.2 11.9 2.96 3.22 3.33 3.01 3.05

Ca 0.74 0.99 3.43 5.10 4.87 7.79 9.01 9.52 0.48 0.48

Mg 0.50 0.67 0.85 0.81 0.71 0.87 1.14 1.17 0.81 0.87

Al 8.63 8.90 8.52 8.56 7.63 2.80 3.58 3.69 5.56 5.84

Si 18.2 18.3 13.0 14.8 13.8 20.2 21.3 20.2 31.7 31.3

P 0.22 0.22 0.22 0.20 0.20 0.20 0.21 0.21 0.07 0.06

Trace elements (in parts per million)

Ti 1.83 1.73 1.68 1.67 1.52 0.27 0.31 0.32 0.42 0.54

Sr 76 82 195 251 242 305 419 429 87 89

Ba 62 61 71 74 81 33 39 49 321 2

270

Cu 183 165 156 141 151 37 56 58 28 2

25

Co 83 84 77 88 80 13 26 23 41 11

Mn 697 900 4,150 3,490 3,380 1,070 690 713 524 513

Ni 474 441 398 384 367 133 163 179 41 30

Zn 246 244 171 141 149 65 71 71 214 191

V 354 321 277 264 279 52 98 112 92 72

Pb 15 16 11 12 13 15 17 29 47 34

Cd 0.60 0.54 0.29 0.30 0.26 0.19 0.18 0.07 0.65 0.59
68 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

1 Cl and SO4 analyzed only in unfiltered samples for dry season sampling

2 Stations shown in figure 9

Table 19. Major-ion concentrations in surface and ground waters in the vicinity of James Campbell National Wildlife Refuge,

Hawaii, November 22, 1994 (dry season) and March 13–14, 1997 (wet season)

[Alkalinity was determined from filtered, unacidified samples, but is listed here under the filtered, acidified category; μeq/L, microequivalents per liter; mg/L,

milligrams per liter; °C, degrees Celsius; Alk, alkalinity; DO, dissolved oxygen, DOsat, dissolved oxygen saturation; Temp, water temperature; major ions are

listed by their elemental symbols; --, not measured]

Sample Station2 Year

Alk

(μeq/L)

Major ions Field measurements

Ca

(mg/L)

Mg

(mg/L)

Na

(mg/L)

Sr

(mg/L)

K

(mg/L)

1Cl

(mg/L)

1SO4

(mg/L) pH

DO

(mg/L)

DOsat

(percent)

Temp

(°C)

Filtered, acidified samples

A 37 1994 2,560 56.5 31.0 112 0.297 2.37 -- -- 6.95 5.9 -- 23.0

A 37 1997 2,400 57.6 31.5 88.1 0.335 2.03 212 30 7.60 7.9 95 25.0

B 36 1994 2,490 61.5 35.5 126 0.387 4.23 -- -- 7.10 5.1 -- 23.0

B 36 1997 2,570 62.6 37.6 123.0 0.426 4.82 297 37 8.15 3.7 45 25.8

C 44 1994 1,540 44.5 30.5 85.5 0.295 4.21 -- -- 7.55 6.2 -- 24.5

C 44 1997 685 25.2 25.2 71.9 0.219 3.70 172 36 7.50 6.9 88 27.9

D 12 1994 5,570 97.0 70.5 267 0.844 25.6 -- -- 8.35 6.6 -- 23.0

D 12 1997 5,050 112 81.7 240 1.04 21.5 405 316 8.15 7.8 99 27.0

E 6 1994 1,560 36.0 22.4 57.0 0.217 2.09 -- -- 6.95 7.6 -- 22.0

E 6 1997 1,570 35.7 22.6 54.1 0.208 2.06 136 24 7.35 7.9 89 21.8

J 6 1997 1,570 35.1 22.4 53.2 0.204 2.06 139 18 7.35 7.9 89 21.8

F 3 1997 2,220 31.8 15.2 57.5 0.155 2.49 98 21 7.20 4.3 50 24.5

G 45 1997 3,420 47.4 23.5 73.8 0.354 3.88 115 27 7.25 3.7 46 24.5

H 4 1997 2,630 39.6 13.0 46.8 0.169 1.80 81 14 7.35 3.2 37 23.8

I 1 1997 1,750 38.3 20.8 82.4 0.204 1.12 178 22 7.05 1.7 20 25.8

Raw (unfiltered), acidified samples

A 37 1994 -- 53.0 30.9 104 0.302 2.30 242 35.8 -- -- -- --

A 37 1997 -- 57.8 31.8 86.8 0.343 1.99 226 32 -- -- -- --

B 36 1994 -- 57.5 34.5 114 0.376 4.24 287 38.5 -- -- -- --

B 36 1997 -- 63.2 37.8 124 0.430 4.85 310 29 -- -- -- --

C 44 1994 -- 43.2 30.0 90.5 0.280 4.19 229 41.5 -- -- -- --

C 44 1997 -- 25.9 25.4 72.0 0.229 3.68 180 21 -- -- -- --

D 12 1994 -- 98.0 73.0 252 0.824 24.4 413 236 -- -- -- --

D 12 1997 -- 114 82.5 238 1.05 22.8 425 338 -- -- -- --

E 6 1994 -- 35.5 22.5 54.0 0.204 2.13 145 23.7 -- -- -- --

E 6 1997 -- 36.1 22.6 53.4 0.215 11.4 142 19 -- -- -- --

J 6 1997 -- 35.6 22.2 53.2 0.211 2.05 137 20 -- -- -- --

F 3 1997 -- 31.9 14.9 58.5 0.161 2.63 97 23 -- -- -- --

G 45 1997 -- 48.0 23.4 75.2 0.357 3.93 133 26 -- -- -- --

H 4 1997 -- 40.1 12.7 47.0 0.172 1.81 81 15 -- -- -- --

I 1 1997 -- 39.0 20.8 82.2 0.210 2.28 173 24 -- -- -- --
Water and Sediment Quality 69

1 Stations shown in figure 9

Table 20. Trace-element concentrations in surface and ground water near James Campbell National Wildlife Refuge, Hawaii,

November 22, 1994 (dry season) and March 13–14, 1997 (wet season)

[Concentrations in micrograms per liter (μg/L); <, less than; determinations for November 1994 dry-season samples by GFAAS (Graphite Furnace Atomic

Absorption Spectrometry) and hydride techniques (As, Hg, Se); determination for March 1997 wet-season samples by ICP-MS (Inductively Coupled Plasma

Mass Spectrometry) and hydride techniques (Hg, Se); the trace elements are listed by their chemical symbols]

Sample Station1 Year Cr Cu Zn Ag Cd Ba Pb Fe Mn As Se Hg

Filtered, acidified samples

A 37 1994 3.4 1.2 <2 <0.1 0.03 9 7 <3 0.1 0.3 1.6 1.1

A 37 1997 2.1 0.8 2.4 0.09 0.11 8.1 0.09 4 4.5 0.5 1.4 0.2

B 36 1994 2.0 1.7 2.0 <0.1 0.04 4 2 16 1.6 2.1 1.8 0.0

B 36 1997 1.0 1.1 0.6 0.08 0.10 7.4 0.12 19 153 4.4 0.9 0.2

C 44 1994 2.1 4.6 <2 <0.1 0.17 4 2 13 13.2 2.6 2.3 0.2

C 44 1997 1.0 2.2 0.6 0.07 0.11 4.8 0.07 3 2.3 2.7 0.9 1.5

D 12 1994 1.7 3.7 <2 <0.1 0.07 10 2 10 41.7 27.0 2.8 0.0

D 12 1997 1.3 2.3 8.9 0.07 0.11 16.8 0.08 6 298 30.6 0.9 2.9

E 6 1994 3.6 1.4 2.0 <0.1 0.16 2 2 15 0.3 0.6 7.0 0.4

E 6 1997 2.4 0.5 <0.5 0.07 0.13 2.9 0.08 2 <0.1 <0.1 1.1 <0.07

J 6 1997 2.5 0.4 <0.5 0.07 0.09 3.0 0.06 4 1.5 <0.1 0.9 0.5

F 3 1997 1.6 1.7 1.8 0.06 0.09 14.2 0.10 135 184 0.7 1.2 0.3

G 45 1997 1.0 0.9 <0.5 0.07 0.09 14.1 0.06 13 273 35.2 0.9 <0.07

H 4 1997 1.5 0.6 <0.5 0.07 0.08 10.1 0.08 2 175 37.9 1.1 0.1

I 1 1997 1.2 0.7 <0.5 0.07 0.10 5.4 0.10 191 115 1.7 0.9 0.1

Raw (unfiltered), acidified samples

A 37 1994 3.3 2.7 <2 <0.1 0.16 13 4 16 1.4 0.1 <0.1 0.3

A 37 1997 2.2 0.8 1.35 0.06 0.09 7.8 0.13 75 5.5 0.6 1.3 0.1

B 36 1994 2.2 3.0 2.0 <0.1 0.14 2 2 133 54.4 1.9 <0.1 <0.1

B 36 1997 1.2 1.2 1.38 0.06 0.09 7.5 0.23 128 176 4.5 1.1 0.6

C 44 1994 6.1 8.2 <2 <0.1 0.12 3 9 1,130 52.5 1.6 <0.1 <0.1

C 44 1997 3.2 3.9 2.70 0.07 0.10 5.9 0.35 965 44.5 2.4 0.8 0.6

D 12 1994 4.0 5.0 <2 <0.1 0.14 14 2 529 99.0 21.0 <0.1 0.5

D 12 1997 3.5 3.5 1.37 0.07 0.11 19.0 0.28 1,200 399 30.6 1.2 <0.07

E 6 1994 3.6 1.6 <2 <0.1 0.08 3 2 17 0.2 <0.1 <0.1 0.6

E 6 1997 2.4 0.4 <0.5 0.06 0.08 2.7 0.06 3 3.0 <0.1 1.4 0.8

J 6 1997 2.5 0.4 <0.5 0.07 0.09 2.7 0.09 <3 2.7 <0.1 1.0 0.4

F 3 1997 3.9 3.0 3.32 0.07 0.09 17.0 0.31 616 213 0.3 1.6 <0.07

G 45 1997 0.6 1.2 1.50 <0.05 <0.04 14.7 0.43 1,050 288 65.2 1.1 <0.07

H 4 1997 0.7 0.5 1.29 <0.05 <0.04 11.0 0.56 138 202 38.7 1.2 <0.07

I 1 1997 1.9 1.1 <0.5 0.08 0.11 5.7 0.25 988 115 3.4 1.2 <0.07
70 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

at pond D, which indicates a flux of dissolved manganese from deeper within the sediment column and

reprecipitation of manganese oxide near the sediment/water interface, are consistent with this hypothesis.

Sediments from Punamano pond contain much

lower concentrations of iron (3 percent) and aluminum

(3 to 4 percent) and much higher calcium (8 to 9 percent) and silicate (20 to 21 percent) than either Kii pond

C or D (table 17). These differences are attributable to

the Punamano pond sediment containing less red clay,

perhaps owing to a combination of ground-water inputs

and effective filtering of terrigenous sediment runoff by

the ample vegetation (reeds) in and around the pond.

Plankton productivity and a pre-existing, reef-carbonate

dominated bottom would also account for the increased

silicate and calcium contents, respectively.

Trace-element concentrations in the Punamano

and Kii sediments (table 18) are generally low and comparable to those observed in other Hawaiian sediments

derived from volcanic soils (for example, De Carlo and

Spencer, 1995; 1997). Metals such as cadmium, cobalt,

copper, nickel, and zinc are enriched about four-fold in

Kii Unit ponds relative to those in Punamano pond. This

coincides with an approximately four-fold difference in

the iron content of the sediments from the two Refuge

units. The positive correlation of trace-element concentrations with iron indicates that most of the trace-element concentrations of the ponds can be accounted for

by an input of natural soil-derived sediment. No significant anthropogenic input of heavy metals to these

ponds is immediately evident. Although concentrations

of cadmium track iron contents, the concentrations are

about two to three-fold higher than reported in uncontaminated soils and sediments (Kabata-Pendias and

Pendias, 1992; De Carlo and Spencer, 1995, 1997). The

elevated cadmium concentration of these sediments

could be derived from three principal sources: automobile tire wear, superphosphate fertilizers, and sewage

(De Carlo and Spencer, 1995; McMurtry and others,

1995). The first source is unlikely as zinc concentrations should be elevated commensurately if automobile

tire wear were responsible for elevated cadmium. The

fertilizer and sewage sources are more likely, although

there is no unequivocal evidence that either source has

contributed to the cadmium concentration of these sediments.

Lead concentrations in sediment (table 18) are uniformly low (11 to 29 ppm) in all three ponds and display

no correlation with iron concentration. The concentrations of this element are comparable to soils from several other locations in Hawaii (Li, 1996) although

slightly greater than those observed in uncontaminated

soils (Kabata-Pendias and Pendias, 1992). These observations suggest that lead input to the Kii and Punamano

pond sediments is derived from aerosol deposition associated with tropospheric transport of Asian dust in addition to local volcanically derived material (Hoffman

and others, 1972). Recent stable lead isotope work by

Spencer and De Carlo (1997) has shown that a significant portion of the lead found outside of developed

areas in Hawaii, such as in ridgetop soils and in suspended sediment in stream reaches within upper undeveloped areas of watersheds, exhibits a remote Asian

dust signature. It is unlikely that Kahuku receives much

anthropogenic lead associated with urbanization and

heavy automobile traffic.

Organic Chemical Analysis

Results of analysis for organic chemical compounds are listed in tables 21 through 23 (at end of

report). In addition to the Quality Assurance and Quality Control (QA/QC) safeguards practiced at the USGS

lab, duplicate water samples also were collected from

the composite Kii artesian wells (samples E and J, table

22) to evaluate field variability and analytical reproducibility of the analyses.

Organic and Nutrient Water Chemistry

Very few organic compounds were detected at

even a trace level in water samples; most were not

detected (tables 21 and 22). In the 1994 (dry-season)

survey, trace concentrations of atrazine were detected in

Kii ponds C and D, and in the Kii artesian wells. Atrazine is a triazine herbicide that has been used widely in

sugarcane cultivation in Hawaii. Atrazine in the Kii

artesian wells may date to when Kahuku Plantation was

in operation (1971 and earlier), inferring long infiltration and travel times in the Koolau aquifer, most likely

prolonged by residence in soil and saprolite of the

uplands unsaturated zone. Traces of simazine also were

found in Punamano pond, Kii ponds C and D, and the

Kii artesian wells. Also detected in Punamano pond was

a trace concentration of chorpyrifos, an organophosphate pesticide. In the 1997 (wet-season) survey, diazinon was detected at the minimum reporting level
Water and Sediment Quality 71

(MRL) at Hospital ditch near Kamehameha Highway.

Diazinon is an organophosphate pesticide used in the

United States on a wide variety of agricultural crops,

ornamentals, domestic animals, lawns, gardens, and

household pests (Sittig, 1985). A trace concentration of

trifluralin, a triazine herbicide, was detected at

Punamano pond. Trifluralin, a di-nitro aniline compound, is a known carcinogen (Sittig, 1985).

The highest concentrations of nitrogen in the form

of ammonia and organic nitrogen were observed in

Punamano pond, Kii ponds C and D, and Kii ditch at

station 3. These results likely reflect natural processes,

including the decomposition of organic matter in the

organic-rich pond sediments and, at Kii ditch, possibly

the decomposition of vegetation in the stream channel

or organic matter in ground water beneath the adjacent

aquaculture ponds. In the 1997 (wet-season) survey, the

highest concentrations of nitrogen in the form of nitrite

and nitrate were at Punamano Spring, the Kii artesian

wells, and Hospital ditch at station 4. Samples from

these sites all contain direct or nearby discharge from

the Koolau aquifer and so implicate a ground-water

source for the nitrite and nitrate. Lesser concentrations

of nitrite and nitrate were found in Punamano ditch at

station 1, Kii ditch at station 3, and Hospital ditch at the

Kii Unit fence. These may reflect dilution of Koolau

aquifer water by ground-water seepage from the alluvial

fans or uptake of nitrite/nitrate by vegetation along the

ditches. Similarly, concentrations of nitrite and nitrate

were below the minimum reporting limit at Kii ponds C

and D, and at the minimum reporting limit at Punamano

pond. The lack of any enrichment of these species indicates a more complete uptake of nitrite and nitrate by

pond vegetation.

Organic Sediment Chemistry

A different suite of organic compounds was found

in sediments compared to water samples (table 23). The

organochlorine pesticide DDT and its breakdown products, DDD and DDE, were detected at or above the minimum reporting limit in surface grab-samples of bottom

sediment from Kii ponds C and D, and in the lower part

of a sediment core taken at Punamano pond. Trace concentrations of ametryn were detected at Kii pond C and

in the lower part of the Punamano core. Trace concentrations of bromacil, carboxin, diphenamid, and simetryn were detected in the upper part of the Punamano

core, and a trace of propachlor was detected at Kii pond

D. The only volatile organic compound detected in any

of the surveys was toluene, at 12 μg/kg, in sediment

from Kii pond C.

Sediment Mineralogy

Identifications of mineral phases were based on

peak comparison of sample X-ray diffraction (XRD)

patterns with those in the Joint Committee for Powder

Diffraction Studies (JCPDS). Identifications are qualitative, although abundance estimates of individual

phases can be made on the basis of relative peak intensities.

The sediments collected from pond C in the Kii

Unit are primarily fine-grained materials, containing a

mixture of clay minerals (including kaolinite) and a

variety of iron oxide minerals, derived from the weathering of volcanic material. Trace amounts of pyrite and

quartz also were detected. The presence of pyrite indicates a low redox state in the sediments, which results

from the oxidation of organic matter settling in the

ponds. Quartz in these sediments is likely of aeolian origin, although a small contribution from hydrothermal/volcanic quartz cannot be entirely ruled out

(Jackson and others, 1971). Surface sediments from this

site are very similar in mineralogical composition to

those found at depth, with the exception of trace

amounts of most likely biogenic calcite occurring in the

deeper sediments.

The mineralogy of sediments from pond D is similar to that of pond C. Notable exceptions include

slightly greater abundances of calcite and pyrite, and the

occurrence of traces of aragonite. Solely on the basis of

peak intensities, the abundance of pyrite also appears

greater in deeper sediments of pond D than in surface

sediments. The increased abundance of pyrite and carbonate minerals in sediments of pond D may reflect a

slightly greater biologic productivity and concomitant

higher oxygen demand in this pond. Initial and subsequent examinations of the ponds consistently revealed a

large difference in the color of the water of these two

ponds. Pond D is generally clearer than pond C, which

is characterized by a brownish color reminiscent of

storm water with a high suspended solid load. The inorganic water chemistry of the two ponds discussed earlier in this report attests further to their difference.

Sediments collected from Punamano pond are generally similar to those from Kii ponds C and D, in that

they consist mainly of clay minerals (including kaolinite) and iron oxide minerals derived from volcanic soil.
72 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

However, biogenic calcite is much more abundant in the

Punamano pond sediments.

Comparison of Trace-Element and Organic

Compound Concentrations in Water and

Bottom Sediment with Water-Quality

Guidelines

Concentrations of some trace elements and organic

compounds increase through higher levels of the food

chain. These increases in concentration can directly

affect Refuge wildlife because these wildlife are high

on the food chain. Studying the effects on wildlife of

trace elements and organic compounds in water and

pond-bottom sediments was beyond the scope of this

study. The presence of trace elements and organic compounds in water and bottom sediments can be related to

their adverse effects on aquatic communities.

Water

Trace-element and organic compound concentrations in filtered- and unfiltered-water samples collected

as part of this study (tables 20, 21, and 22) were compared against U.S. Environmental Protection Agency

ambient water-quality criteria for protection of aquatic

life and human health (U.S. Environmental Protection

Agency, 1986). All constituents analyzed were below

these criteria except for copper in a sample collected

from Kii Pond C during the 1994 (dry-season) survey.

The copper concentration in this unfiltered sample was

8.2 μg/L (table 20), as compared to the aquatic life

chronic criteria of 6.5 μg/L.

Pond-Bottom Sediment

The potential for adverse biological effects associated with contaminated sediment was assessed using

interim sediment-quality guidelines [threshold effect

level (TEL), and probable effect level (PEL)] for freshwater sediments (Canadian Council of Ministers of the

Environment, 1999). Sediment chemical concentrations

below the TELs are not expected to be associated with

any adverse biological effects, while concentrations

above the PELs are expected to be frequently associated

with adverse biological effects. Chemical concentrations between the TELs and PELs represent the range in

which effects are occasionally observed.

The National Status and Trends Program (NSTP)

approach (Long and Morgan, 1990) with modifications

was used to derive TEL and PEL values. This approach

involves the evaluation and compilation of chemical

and biological data from numerous studies (including

models of equilibrium partitioning in sediments, sediment-quality assessments values, spiked sediment toxicity tests and field studies) conducted throughout North

America. The available data covered a large and varied

geographic area and included many different species

and biological endpoints. However, it should be noted

that the guidelines are not based on a toxicological

response and do not directly infer a cause and effect

relation among chemical concentrations in sediment

and the uptake of these chemicals by aquatic organisms.

As a result, the following screening for exceedance of

these interim sediment-quality guidelines (PELs and

TELs) should be used only to determine which chemicals and locations are likely to be associated with

adverse biological effects. Site-specific biological

assessments and other measures of biological effects

should be used in conjunction with these numerical

guidelines to support practical and informed decisions

regarding sediment quality.

Trace-element and organic compound data from

the Kii and Punamano Ponds (tables 18 and 23) were

compared with the Canadian interim sediment-quality

guidelines for freshwater sediments. Copper concentrations in sediments from Kii ponds C and D (141 to 183

ppm) exceeded the PEL and TEL guidelines (108 and

18.7 ppm, respectively), and zinc concentrations (141 to

246 ppm) exceeded the TEL guideline for zinc (124

ppm). In sediments from Punamano pond, copper concentrations (37 to 58 ppm) exceeded just the TEL guideline (18.7 ppm). Despite exceeding sediment-quality

guidelines, copper and zinc are naturally abundant in

Hawaiian volcanic soils, and concentrations in Refuge

sediments were comparable to or only slightly higher

than those of stream sediments near the head of Manoa

Valley in Honolulu (copper 146 ppm, zinc 228 ppm; De

Carlo and Spencer, 1995), which presumably have been

little affected by anthropogenic sources. Therefore,

anthropogenic sources of copper and zinc to the Refuge

are not strongly indicated by the data, although there

may have been some contribution from periodic flooding or from the pre-1971 use of the ponds for settling of

sugarcane washing and processing waters. All other

trace-element and organic compound concentrations

were less than the sediment-quality guidelines for freshwater sediments.
Summary and Conclusions 73

SUMMARY AND CONCLUSIONS

A hydrologic investigation was done over the 16-

month period November 1996 through February 1998

to identify and quantify principal inflows and outflows

of water to and from the James Campbell National

Wildlife Refuge, determine the adequacy of the current

freshwater supply, identify hydraulic factors affecting

flooding, document ground-water/surface-water interactions, and determine the water- and sediment quality.

Streamflow during the study was dominated by

winter stormflows, followed by a gradual recession of

flow into summer 1997 as water that had been stored in

alluvial fans drained to lowland ditches. Ohia Ai Gulch

accounted for 89 percent of upland runoff in 1997

owing to its large drainage basin which extends into the

rainy uplands. Outflow at the ditch terminus in 1997

was 125 Mgal greater than measured inflow to the

coastal plain, mainly reflecting gains from ground water

along the ditches between outlying gages and the ditch

terminus. In September 1997, measured inflow was

almost negligible, yet the Kii outlet pump discharged

7.99 Mgal, most of which must have originated as

ground-water discharge. Of the measured 1997 outflow,

98 percent was through the Kii outlet pump, with the

outlet culvert valve only opening for brief periods during storms. Large volumes of stormflow escaped over

the flood-relief swales unmeasured.

During the largest storm of the study, in November

1996, Kalaeokahipa Stream and Hospital ditch overtopped Kamehameha Highway, apparently due to

exceedance of culvert capacity, though Kalaeokahipa

bridge may have been partly obstructed by vegetation.

Slight overbank flooding in Kii ditch resulted strictly

from high discharge (no backwater effect was evident).

Minor overbank flooding farther out on the coastal plain

was likely caused principally by the small hydraulic

gradients available to convey stormflows along the lowland ditches. Stormwaters flooded Kii ponds and

flowed back upstream along Punamano ditch into

Punamano marsh, introducing suspended sediment and

possibly other contaminants to the Refuge. By analyzing records from nearby long-term stream-gaging stations, the November 1996 storm is estimated to have a

flood frequency of about 3 to 4 years. Two smaller

storms in January 1997 resulted in smaller flows and no

overbank flooding. The Kii outlet pump ran continuously with no shutoff for 7 days during the November

1996 storm and for 1 to 2 days during the January 1997

storms. During all three storms, the outlet culvert valve

opened and the inner ditches overtopped the flood-relief

swales, allowing free outflow of water from the inner

ditch.

Backwater effects hindered drainage during the

January 1997 storms at Hospital ditch at Kamehameha

Highway, and at Punamano ditch at Nudist Camp Road

(where the backflow into Punamano marsh in November 1996 constituted an extreme backwater effect). A

probable marine backwater effect was imposed at the

ocean outlet ditch during the November 1996 storm

through a combination of high spring tides and wave

setup from large surf. Whether this backwater effect

propagated upstream in the ditches to affect inland sites

could not be determined conclusively. A sand plug may

have built up in the ocean outlet channel before the

November 1996 storm, but if so, it was probably

washed out before or early in the storm, and was not

present at the time of peak stage at inland sites. A season-long buildup of the sand plug in late 1997 was

inferred from rising water levels in the outlet ditch. Seawater washes up the outlet channel or over the sand

berm and into the outer ditch system on most high tides,

and particularly during spring high tides.

Ponds and ditches of the Refuge and surrounding

lowlands have mud- and clay-lined bottoms that form

an effective confining unit and inhibit interaction with

an underlying shallow limestone aquifer. Kii pond levels are higher than adjacent ditch levels and underlying

ground-water levels, establishing lateral and downward

head gradients that could foster seepage losses from the

ponds. Regional ground-water discharge from the

Koolau aquifer to the coastal lowlands must be large,

but discharge was evident only at a few known springs,

suggesting that seepage is pervasive but diffuse. A

regional salinity survey detected concentrated freshwater discharge where ridges of Koolau Basalt extend

beneath coastal-plain sediments near Punamano Unit

and at the head of Hospital ditch, and also detected

brackish ground-water discharge into Kii ditch downstream of Kamehameha Highway. Wastewater disposal

from the sewage treatment plant adjoining Kii Unit

poses little or no threat to Refuge habitat. Disposal is

actually at six injection wells 0.45 mile away at

Kahuku, and the wells inject into confined limestone

aquifers that do not extend to Kii Unit.

The natural freshwater supply to Punamano Unit is

adequate, judging from stable pond levels and low
74 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

salinities there. A monthly water budget for Punamano

showed an apparent annual deficit in water supply in

1997, requiring unmeasured ground-water gains equalling 50.8 inches of water over the Punamano ponds and

wetlands. The freshwater supply to Kii Unit is inadequate according to Refuge managers, who state that

there is not enough water to manipulate levels adequately in the ponds during most of the year, and particularly during the driest months. This is confirmed by

monthly deficits in the water budget for the Kii ponds

during summer months. However on an annual basis,

the Kii budget showed a surplus in supply for 1997

equalling 24.0 inches of water over the ponds fed by the

artesian wells. Unmeasured losses are required to

explain the apparent surplus, such as discharge to the

ditches through pond water-control structures and

downward or lateral ground-water seepage. The apparent annual surplus at Kii is strictly hydrologic and is not

a surplus in a management sense; it cannot be stored or

used to supply the Refuge, but instead reflects losses

from the system that render this amount of water

unavailable for use. The budget year, 1997, was drier

than normal (24 percent below long-term mean rainfall)

and so the measured potential evaporation for 1997 is

probably higher than the long-term mean.

Few metals or organic compounds of potential

concern were detected in pond and ditch waters and in

pond-bottom sediments. Detected pesticides were at

trace levels or just above minimum reporting limits.

Exceptions that exceeded sediment quality guidelines

include copper and zinc in sediment from Kii ponds C

and D, and copper in sediment from Punamano pond.

All other elements and organic compounds were at concentrations less than the guidelines for freshwater sediments. Judging from these results, urban and

agricultural runoff appear to have contributed little in

the way of harmful metals or organic compounds to the

Refuge, although the potential for such contribution

remains in the form of periodic flooding of the ponds by

ditch stormflows. Salinity was low throughout most

Refuge waters, qualifying as fresh to slightly brackish

and more than suitable for the environmental needs of

Refuge fauna. Higher salinities have been observed in

ditches during past periods of sugarcane cultivation and

saltwater aquaculture, however. Resumption of saltwater aquaculture could raise ditch salinities if saltwater

effluents are disposed directly into the ditches, as they

were in the past.

REFERENCES CITED

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Table 21 77

Table 21. Organic compounds and nutrients in surface and ground water near James Campbell National Wildlife Refuge, Hawaii, November 22, 1994 (dry

season)

[ --, compound not detected and can be considered to be less than the reporting limit; <, less than; trace, compound detected, but at concentration less than the reporting limit; mg/L, milligrams per liter;μg/L, micrograms per liter; n.a., not available (sample unintentionally destroyed); analyses were performed by the USGS National Water Quality Laboratory in Denver, Colorado]

Chemical constituent Units

Sample designation, station number, location1

Minimum

reporting limit

A, 37,

Punamano

Spring

B, 36,

Punamano

pond

C, 44,

Kii pond C

D, 12,

Kii pond D

E, 6,

Kii wells

Nutrients (USGS schedule 9)

Nitrogen, ammonia + organic nitrogen, as N mg/L -- .5 .9 1.7 -- < .2Nitrogen, nitrite, as N mg/L -- -- -- -- -- < .01Phosphorus, total, as P mg/L 0.1 .08 .23 .24 .06 < .01

Chlorophenoxy acid herbicides, water (USGS schedule 1304)

2,4-D μg/L -- -- -- -- -- < .01

2,4-Dp dichlorprop μg/L -- -- -- -- -- < .01

2,4,5-T μg/L -- -- -- -- -- < .01

Silvex μg/L -- -- -- -- -- < .01

Organophosphate pesticides, total in water (USGS schedule 1319)

Chorpyrifos μg/L -- trace -- -- -- < .01

DEF S,S,S-Tributylphosphorotrithioate μg/L -- -- -- -- -- < .01

Diazinon μg/L -- -- -- -- -- < .01

Disulfoton μg/L -- -- -- -- -- < .01

Ethion μg/L -- -- -- -- -- < .01

Malathion μg/L -- -- -- -- -- < .01

Parathion μg/L -- -- -- -- -- < .01

Parathion-methyl μg/L -- -- -- -- -- < .01

Phorate μg/L -- -- -- -- -- < .01

Trithion μg/L -- -- -- -- -- < .01

Organochlorine pesticides, total in water (USGS schedule 1324)

Aldrin μg/L -- -- -- -- -- < .01

Chlordane μg/L -- -- -- -- -- < .1

Dieldrin μg/L -- -- -- -- -- < .01

Endosulfan μg/L -- -- -- -- -- < .01

Endrin μg/L -- -- -- -- -- < .01

Heptachlor μg/L -- -- -- -- -- < .01

Heptachlor epoxide μg/L -- -- -- -- -- < .01

Lindane μg/L -- -- -- -- -- < .01

p,p′-Methoxychlor μg/L -- -- -- -- -- < .01

Mirex μg/L -- -- -- -- -- < .01

Perthane μg/L -- -- -- -- -- < .1

Polychlorinated biphenyls μg/L -- -- -- -- -- < .1

Polychlorinated napthalenes μg/L -- -- -- -- -- < .1

p,p'-DDD μg/L -- -- -- -- -- < .01

p,p'-DDE μg/L -- -- -- -- -- < .01

p,p'-DDT μg/L -- -- -- -- -- < .01

Toxaphene μg/L -- -- -- -- -- < 1
78 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii Triazine herbicides, dissolved (USGS schedule 1379) Alachlor

μg/L -- -- -- -- -- < .05

Ametryn

μg/L -- -- -- -- -- < .05

Atrazine

μg/L -- -- trace trace trace < .05

Cyanazine

μg/L -- -- -- -- -- < .2

Desethylatrazine

μg/L -- -- -- -- -- < .05

Deisopropylatrazine

μg/L -- -- -- -- -- < .05

Metolachlor

μg/L -- -- -- -- -- < .05

Metribuzin

μg/L -- -- -- -- -- < .05

Prometon

μg/L -- -- -- -- -- < .05

Prometryn

μg/L -- -- -- -- -- < .05

Propazine

μg/L -- -- -- -- -- < .05

Simazine

μg/L -- trace trace trace trace < .05

Volatile organic compounds (VOC's), water (USGS schedule 1380; USEPA method 524.2)

1,1,1,2-Tetrachloroethane

μg/L -- n.a. -- -- -- < .2

1,1,1-Trichloroethane

μg/L -- n.a. -- -- -- < .2

1,1,2,2-Tetrachloroethane

μg/L -- n.a. -- -- -- < .2

1,1,2-Trichloroethane

μg/L -- n.a. -- -- -- < .2

1,1,2-Trichlorotrifluoroethane

μg/L -- n.a. -- -- -- < .2

1,1-Dichloroethane

μg/L -- n.a. -- -- -- < .2

1,1-Dichloroethylene (ethene)

μg/L -- n.a. -- -- -- < .2

1,1-Dichloropropene

μg/L -- n.a. -- -- -- < .2

1,2,3-Trichlorobenzene

μg/L -- n.a. -- -- -- < .2

1,2,3-Trichloropropane

μg/L -- n.a. -- -- -- < .2

1,2,4-Trichlorobenzene

μg/L -- n.a. -- -- -- < .2

1,2,4-Trimethylbenzene

μg/L -- n.a. -- -- -- < .2

1,2-Dibromo-3-chloropropane (DBCP)

μg/L -- n.a. -- -- -- < 1

1,2-Dibromoethane (EDB)

μg/L -- n.a. -- -- -- < .2

1,2-Dichlorobenzene

μg/L -- n.a. -- -- -- < .2

1,2-Dichloroethane

μg/L -- n.a. -- -- -- < .2

1,2-Dichloropropane

μg/L -- n.a. -- -- -- < .2

1,3,5-Trimethylbenzene

μg/L -- n.a. -- -- -- < .2

1,3-Dichlorobenzene

μg/L -- n.a. -- -- -- < .2

1,3-Dichloropropane

μg/L -- n.a. -- -- -- < .2

1,4-Dichlorobenzene

μg/L -- n.a. -- -- -- < .2

1-Chloro-4-methylbenzene (4-chlorotoluene)

μg/L -- n.a. -- -- -- < .2

2,2-Dichloropropane

μg/L -- n.a. -- -- -- < .2

2-Chloroethylvinylether

μg/L -- n.a. -- -- -- < 1

2-Chlorotoluene

μg/L -- n.a. -- -- -- < .2

Table 21. Organic compounds and nutrients in surface and ground water near James Campbell National Wildlife Refuge, Hawaii, November 22, 1994 (dry

season)--Continued

[ --, compound not detected and can be considered to be less than the reporting limit; <, less than; trace, compound detected, but at concentration less than the reporting limit; mg/L, milligrams per liter;μg/L, micrograms per liter; n.a., not available (sample unintentionally destroyed); analyses were performed by the USGS National Water Quality Laboratory in Denver, Colorado]

Chemical constituent Units

Sample designation, station number, location1

Minimum

reporting limit

A, 37,

Punamano

Spring

B, 36,

Punamano

pond

C, 44,

Kii pond C

D, 12,

Kii pond D

E, 6,

Kii wells
Table 21 79 1 Stations shown in figure 9

Volatile organic compounds (VOC's), water (USGS schedule 1380; USEPA method 524.2)--Continued

4-Isopropyl-1-methylbenzene (p-isopropyltoluene) μg/L -- n.a. -- -- -- < .2

Benzene μg/L -- n.a. -- -- -- < .2

Bromobenzene μg/L -- n.a. -- -- -- < .2

Bromochloromethane μg/L -- n.a. -- -- -- < .2

Bromodichloromethane μg/L -- n.a. -- -- -- < .2

Bromoform μg/L -- n.a. -- -- -- < .2

Bromomethane μg/L -- n.a. -- -- -- < 2

Butylbenzene (N-butylbenzene) μg/L -- n.a. -- -- -- < .2

Chlorobenzene μg/L -- n.a. -- -- -- < .2

Chloroethane μg/L -- n.a. -- -- -- < 2

Chloroform μg/L -- n.a. -- -- -- < .2

Chloromethane μg/L -- n.a. -- -- -- < 2

cis-1,2-Dichloroethylene (ethene) μg/L -- n.a. -- -- -- < .2

cis-1,3-Dichloropropene μg/L -- n.a. -- -- -- < .2

Dibromochloromethane μg/L -- n.a. -- -- -- < .2

Dibromomethane μg/L -- n.a. -- -- -- < .2

Dichlorodifluoromethane μg/L -- n.a. -- -- -- < 2

Dichloromethane μg/L -- n.a. -- -- -- < .2

Ethylbenzene μg/L -- n.a. -- -- -- < .2

Hexachlorobutadiene μg/L -- n.a. -- -- -- < .2

Isopropylbenzene μg/L -- n.a. -- -- -- < .2

Naphthalene μg/L -- n.a. -- -- -- < .2

Propylbenzene μg/L -- n.a. -- -- -- < .2

sec-Butylbenzene μg/L -- n.a. -- -- -- < .2

Styrene μg/L -- n.a. -- -- -- < .2

tert-Butyl methyl ether μg/L -- n.a. -- -- -- < .2

tert-Butylbenzene μg/L -- n.a. -- -- -- < .2

Tetrachloroethylene (ethene) μg/L -- n.a. -- -- -- < .2

Tetrachloromethane (carbon tetrachloride) μg/L -- n.a. -- -- -- < .2

Toluene μg/L -- n.a. -- -- -- < .2

trans-1,2-Dichloroethylene (ethene) μg/L -- n.a. -- -- -- < .2

trans-1,3-Dichloropropene μg/L -- n.a. -- -- -- < .2

Trichloroethylene (ethene) μg/L -- n.a. -- -- -- < .2

Trichlorofluoromethane μg/L -- n.a. -- -- -- < .2

Vinyl chloride μg/L -- n.a. -- -- -- < 2

Xylene (dimethylbenzene) μg/L -- n.a. -- -- -- < .2

Table 21. Organic compounds and nutrients in surface and ground water near James Campbell National Wildlife Refuge, Hawaii, November 22, 1994 (dry

season)--Continued

[ --, compound not detected and can be considered to be less than the reporting limit; <, less than; trace, compound detected, but at concentration less than the reporting limit; mg/L, milligrams per liter;μg/L, micrograms per liter; n.a., not available (sample unintentionally destroyed); analyses were performed by the USGS National Water Quality Laboratory in Denver, Colorado]

Chemical constituent Units

Sample designation, station number, location1

Minimum

reporting limit

A, 37,

Punamano

Spring

B, 36,

Punamano

pond

C, 44,

Kii pond C

D, 12,

Kii pond D

E, 6,

Kii wells
80 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii Table 22. Organic compounds and nutrients in surface and ground water near James Campbell National Wildlife Refuge, March 13–14, 1997 (wet season) [--, compound not detected and can be considered to be "less than" the reporting limit; <, less than; trace, compound detected, but at concentration less than the reporting limit; mg/L, milligrams per liter; μg/L, micrograms per liter; analyses were performed by the USGS National Water Quality Laboratory in Denver, Colorado] Chemical constituent Units Sample designation, station number, location1 Minimum reporting limit A, 37, Punamano Spring B, 36, Punamano pond C, 44, Kii pond

C

D, 12,

Kii pond

D

E, 6,

Kii wells

F, 3

Kii ditch

G, 45,

Hospital

ditch

H, 4,

Kahuku

storm

drain

I, 1

Punamano

ditch

J, 6,

Kii wells

duplicate

Nutrients + microkjeldahl P (USGS schedule 116)

Nitrogen, ammonia, as N mg/L -- .02 -- -- -- .05 -- -- .05 -- < .015Nitrogen, ammonia + organic nitrogen, as N mg/L -- .04 .4 .7 -- .2 -- -- -- -- < .2Nitrogen, nitrite, as N mg/L 0.01 .02 .01 .02 .01 .02 .02 .02 .03 .01 < .01Nitrogen, nitrite + nitrate, as N mg/L 1.1 .05 -- -- .95 .22 .09 1.1 .35 .96 < .05Phosphorus, phosphate, ortho-, as P mg/L .09 .12 -- .07 .05 -- .02 .11 .03 .05 < .01Phosphorus, total, as P mg/L .1 .12 .05 .07 .01 -- .06 .09 .02 .02 < .01

Chlorophenoxy acid herbicides, water (USGS schedule 1304)

2,4-D

μg/L -- -- -- -- -- -- -- -- -- -- < .01

2,4-Dp dichlorprop

μg/L -- -- -- -- -- -- -- -- -- -- < .01

2,4,5-T

μg/L -- -- -- -- -- -- -- -- -- -- < .01

Silvex

μg/L -- -- -- -- -- -- -- -- -- -- < .01

Organophosphate pesticides, total in water (USGS schedule 1319)

Chorpyrifos

μg/L -- -- -- -- -- -- -- -- -- -- < .01

DEF S,S,S-Tributylphosphorotrithioate

μg/L -- -- -- -- -- -- -- -- -- -- < .01

Diazinon

μg/L -- -- -- -- -- -- .01 -- -- -- < .01

Disulfoton

μg/L -- -- -- -- -- -- -- -- -- -- < .01

Ethion

μg/L -- -- -- -- -- -- -- -- -- -- < .01

Fonofos

μg/L -- -- -- -- -- -- -- -- -- -- < .01

Malathion

μg/L -- -- -- -- -- -- -- -- -- -- < .01

Parathion

μg/L -- -- -- -- -- -- -- -- -- -- < .01

Parathion-methyl

μg/L -- -- -- -- -- -- -- -- -- -- < .01

Phorate

μg/L -- -- -- -- -- -- -- -- -- -- < .01

Trithion

μg/L -- -- -- -- -- -- -- -- -- -- < .01

Organochlorine pesticides, total in water (USGS schedule 1324)

Aldrin

μg/L -- -- -- -- -- -- -- -- -- -- < .01

Chlordane

μg/L -- -- -- -- -- -- -- -- -- -- < .1

Dieldrin

μg/L -- -- -- -- -- -- -- -- -- -- < .01

Endosulfan

μg/L -- -- -- -- -- -- -- -- -- -- < .01

Endrin

μg/L -- -- -- -- -- -- -- -- -- -- < .01

Heptachlor

μg/L -- -- -- -- -- -- -- -- -- -- < .01

Heptachlor epoxide

μg/L -- -- -- -- -- -- -- -- -- -- < .01

Lindane

μg/L -- -- -- -- -- -- -- -- -- -- < .01

p,p′-Methoxychlor

μg/L -- -- -- -- -- -- -- -- -- -- < .01

Mirex

μg/L -- -- -- -- -- -- -- -- -- -- < .01

Perthane

μg/L -- -- -- -- -- -- -- -- -- -- < .1

Polychlorinated biphenyls

μg/L -- -- -- -- -- -- -- -- -- -- < .1
Table 22 81

Organochlorine pesticides, total in water (USGS schedule 1324)--Continued

Polychlorinated napthalenes μg/L -- -- -- -- -- -- -- -- -- -- < .1

p,p′-DDD μg/L -- -- -- -- -- -- -- -- -- -- < .01

p,p′-DDE μg/L -- -- -- -- -- -- -- -- -- -- < .01

p,p′-DDT μg/L -- -- -- -- -- -- -- -- -- -- < .01

Toxaphene μg/L -- -- -- -- -- -- -- -- -- -- < 1

Triazine herbicides, dissolved (USGS schedule 1379)

Acetochlor μg/L -- -- -- -- -- -- -- -- -- -- < .05

Alachlor μg/L -- -- -- -- -- -- -- -- -- -- < .05

Ametryn μg/L -- -- -- -- -- -- -- -- -- -- < .05

Atrazine μg/L -- -- -- -- -- -- -- -- -- -- < .05

Bromacil μg/L -- -- -- -- -- -- -- -- -- -- < .05

Butachlor μg/L -- -- -- -- -- -- -- -- -- -- < .05

Butylate μg/L -- -- -- -- -- -- -- -- -- -- < .05

Carboxin μg/L -- -- -- -- -- -- -- -- -- -- < .05

Cyanazine μg/L -- -- -- -- -- -- -- -- -- -- < .2

Cycloate μg/L -- -- -- -- -- -- -- -- -- -- < .05

Desethylatrazine μg/L -- -- -- -- -- -- -- -- -- -- < .05

Desisopropylatrazine μg/L -- -- -- -- -- -- -- -- -- -- < .05

Diphenamid μg/L -- -- -- -- -- -- -- -- -- -- < .05

Hexazinone μg/L -- -- -- -- -- -- -- -- -- -- < .05

Metolachlor μg/L -- -- -- -- -- -- -- -- -- -- < .05

Metribuzin μg/L -- -- -- -- -- -- -- -- -- -- < .05

Prometon μg/L -- -- -- -- -- -- -- -- -- -- < .05

Prometryn μg/L -- -- -- -- -- -- -- -- -- -- < .05

Propachlor μg/L -- -- -- -- -- -- -- -- -- -- < .05

Propazine μg/L -- -- -- -- -- -- -- -- -- -- < .05

Simazine μg/L -- -- -- -- -- -- -- -- -- -- < .05

Simetryn μg/L -- -- -- -- -- -- -- -- -- -- < .05

Terbacil μg/L -- -- -- -- -- -- -- -- -- -- < .05

Trifluralin μg/L -- trace -- -- -- -- -- -- -- -- < .05

Vernolate μg/L -- -- -- -- -- -- -- -- -- -- < .05

Volatile organic compounds (VOC's), water (USGS schedule 1380; USEPA method 524.2)

1,1,1,2-Tetrachloroethane μg/L -- -- -- -- -- -- -- -- -- -- < .2

1,1,1-Trichloroethane μg/L -- -- -- -- -- -- -- -- -- -- < .2

1,1,2,2-Tetrachloroethane μg/L -- -- -- -- -- -- -- -- -- -- < .2

1,1,2-Trichloroethane μg/L -- -- -- -- -- -- -- -- -- -- < .2

1,1,2-Trichlorotrifluoroethane μg/L -- -- -- -- -- -- -- -- -- -- < .2

Table 22. Organic compounds and nutrients in surface and ground water near James Campbell National Wildlife Refuge, March 13–14, 1997 (wet season)--Continued

[--, compound not detected and can be considered to be "less than" the reporting limit; <, less than; trace, compound detected, but at concentration less than the reporting limit; mg/L, milligrams per liter; μg/L,micrograms per liter; analyses were performed by the USGS National Water Quality Laboratory in Denver, Colorado]

Chemical constituent Units

Sample designation, station number, location1

Minimum

reporting

limit

A, 37,

Punamano

Spring

B, 36,

Punamano

pond

C, 44,

Kii pond

C

D, 12,

Kii pond

D

E, 6,

Kii wells

F, 3

Kii ditch

G, 45,

Hospital

ditch

H, 4,

Kahuku

storm

drain

I, 1

Punamano

ditch

J, 6,

Kii wells

duplicate
82 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii Volatile organic compounds (VOC's), water (USGS schedule 1380; USEPA method 524.2)--Continued 1,1-Dichloroethane

μg/L -- -- -- -- -- -- -- -- -- -- < .2

1,1-Dichloroethylene (ethene)

μg/L -- -- -- -- -- -- -- -- -- -- < .2

1,1-Dichloropropene

μg/L -- -- -- -- -- -- -- -- -- -- < .2

1,2,3-Trichlorobenzene

μg/L -- -- -- -- -- -- -- -- -- -- < .2

1,2,3-Trichloropropane

μg/L -- -- -- -- -- -- -- -- -- -- < .2

1,2,4-Trichlorobenzene

μg/L -- -- -- -- -- -- -- -- -- -- < .2

1,2,4-Trimethylbenzene

μg/L -- -- -- -- -- -- -- -- -- -- < .2

1,2-Dibromo-3-chloropropane (DBCP)

μg/L -- -- -- -- -- -- -- -- -- -- < 1

1,2-Dibromoethane (EDB)

μg/L -- -- -- -- -- -- -- -- -- -- < .2

1,2-Dichlorobenzene

μg/L -- -- -- -- -- -- -- -- -- -- < .2

1,2-Dichloroethane

μg/L -- -- -- -- -- -- -- -- -- -- < .2

1,2-Dichloropropane

μg/L -- -- -- -- -- -- -- -- -- -- < .2

1,3,5-Trimethylbenzene

μg/L -- -- -- -- -- -- -- -- -- -- < .2

1,3-Dichlorobenzene

μg/L -- -- -- -- -- -- -- -- -- -- < .2

1,3-Dichloropropane

μg/L -- -- -- -- -- -- -- -- -- -- < .2

1,4-Dichlorobenzene

μg/L -- -- -- -- -- -- -- -- -- -- < .2

1-Chloro-4-methylbenzene (4-chlorotoluene)

μg/L -- -- -- -- -- -- -- -- -- -- < .2

2,2-Dichloropropane

μg/L -- -- -- -- -- -- -- -- -- -- < .2

2-Chlorotoluene

μg/L -- -- -- -- -- -- -- -- -- -- < .2

4-Isopropyl-1-methylbenzene (p-isopropyltoluene)

μg/L -- -- -- -- -- -- -- -- -- -- < .2

Benzene

μg/L -- -- -- -- -- -- -- -- -- -- < .2

Bromobenzene

μg/L -- -- -- -- -- -- -- -- -- -- < .2

Bromochloromethane

μg/L -- -- -- -- -- -- -- -- -- -- < .2

Bromodichloromethane

μg/L -- -- -- -- -- -- -- -- -- -- < .2

Bromoform

μg/L -- -- -- -- -- -- -- -- -- -- < .2

Bromomethane

μg/L -- -- -- -- -- -- -- -- -- -- < .2

Butylbenzene (

N-Butylbenzene)

μg/L -- -- -- -- -- -- -- -- -- -- < .2

Chlorobenzene

μg/L -- -- -- -- -- -- -- -- -- -- < .2

Chloroethane

μg/L -- -- -- -- -- -- -- -- -- -- < .2

Chloroform

μg/L -- -- -- -- -- -- -- -- -- -- < .2

Chloromethane

μg/L -- -- -- -- -- -- -- -- -- -- < .2

cis-1,2-Dichloroethylene (ethene)

μg/L -- -- -- -- -- -- -- -- -- -- < .2

cis-1,3-Dichloropropene

μg/L -- -- -- -- -- -- -- -- -- -- < .2

Dibromochloromethane

μg/L -- -- -- -- -- -- -- -- -- -- < .2

Dibromomethane

μg/L -- -- -- -- -- -- -- -- -- -- < .2

Dichlorodifluoromethane

μg/L -- -- -- -- -- -- -- -- -- -- < .2

Dichloromethane (methylene chloride)

μg/L -- -- -- -- -- -- -- -- -- -- < .2

Ethylbenzene

μg/L -- -- -- -- -- -- -- -- -- -- < .2

Hexachlorobutadiene

μg/L -- -- -- -- -- -- -- -- -- -- < .2

Table 22. Organic compounds and nutrients in surface and ground water near James Campbell National Wildlife Refuge, March 13–14, 1997 (wet season)--Continued

[--, compound not detected and can be considered to be "less than" the reporting limit; <, less than; trace, compound detected, but at concentration less than the reporting limit; mg/L, milligrams per liter; μg/L,micrograms per liter; analyses were performed by the USGS National Water Quality Laboratory in Denver, Colorado]

Chemical constituent Units

Sample designation, station number, location1

Minimum

reporting

limit

A, 37,

Punamano

Spring

B, 36,

Punamano

pond

C, 44,

Kii pond

C

D, 12,

Kii pond

D

E, 6,

Kii wells

F, 3

Kii ditch

G, 45,

Hospital

ditch

H, 4,

Kahuku

storm

drain

I, 1

Punamano

ditch

J, 6,

Kii wells

duplicate
Table 22 83

1 Stations shown in figure 9

Volatile organic compounds (VOC's), water (USGS schedule 1380; USEPA method 524.2)--Continued

Isopropylbenzene μg/L -- -- -- -- -- -- -- -- -- -- < .2

Naphthalene μg/L -- -- -- -- -- -- -- -- -- -- < .2

Propylbenzene μg/L -- -- -- -- -- -- -- -- -- -- < .2

sec-Butylbenzene μg/L -- -- -- -- -- -- -- -- -- -- < .2

Styrene μg/L -- -- -- -- -- -- -- -- -- -- < .2

tert-Butyl methyl ether (MTBE) μg/L -- -- -- -- -- -- -- -- -- -- < .2

tert-Butylbenzene μg/L -- -- -- -- -- -- -- -- -- -- < .2

Tetrachloroethylene (ethene) μg/L -- -- -- -- -- -- -- -- -- -- < .2

Tetrachloromethane (carbon tetrachloride) μg/L -- -- -- -- -- -- -- -- -- -- < .2

Toluene μg/L -- -- -- -- -- -- -- -- -- -- < .2

trans-1,2-Dichloroethylene (ethene) μg/L -- -- -- -- -- -- -- -- -- -- < .2trans-1,3-Dichloropropene μg/L -- -- -- -- -- -- -- -- -- -- < .2Trichloroethylene (ethene) μg/L -- -- -- -- -- -- -- -- -- -- < .2

Trichlorofluoromethane μg/L -- -- -- -- -- -- -- -- -- -- < .2

Vinyl chloride μg/L -- -- -- -- -- -- -- -- -- -- < .2

Xylene (dimethylbenzene) μg/L -- -- -- -- -- -- -- -- -- -- < .2

Table 22. Organic compounds and nutrients in surface and ground water near James Campbell National Wildlife Refuge, March 13–14, 1997 (wet season)--Continued

[--, compound not detected and can be considered to be "less than" the reporting limit; <, less than; trace, compound detected, but at concentration less than the reporting limit; mg/L, milligrams per liter; μg/L,micrograms per liter; analyses were performed by the USGS National Water Quality Laboratory in Denver, Colorado]

Chemical constituent Units

Sample designation, station number, location1

Minimum

reporting

limit

A, 37,

Punamano

Spring

B, 36,

Punamano

pond

C, 44,

Kii pond

C

D, 12,

Kii pond

D

E, 6,

Kii wells

F, 3

Kii ditch

G, 45,

Hospital

ditch

H, 4,

Kahuku

storm

drain

I, 1

Punamano

ditch

J, 6,

Kii wells

duplicate
84 Hydrology and Water and Sediment Quality at James Campbell National Wildlife Refuge near Kahuku, Island of Oahu, Hawaii

Table 23. Organic compounds in pond-bottom sediments at James Campbell National Wildlife Refuge, Oahu, Hawaii, December

28, 1994 (dry season)

[Reporting limits varied from sample to sample for some constituents; --, compound not detected and can be considered to be "less than" the reporting limit; <,

less than; trace, compound detected, but at concentration less than the reporting limit; μg/kg, micrograms per kilogram; est., estimated; analyses were performed

by the USGS National Water Quality Laboratory in Denver, Colorado; do., ditto]

Chemical constituent Units

Sample designation Minimum reporting limit

Punamano

north pond

(top of

sediment

core)

Punamano

north pond

(bottom of

sediment

core)

Kii pond

C, grab

sample

(top of

sediment)

Kii pond

D, grab

sample

(top of

sediment)

For all

samples

By individual sample

Punamano

north pond

(top of

sediment

core)

Punamano

north pond

(bottom of

sediment

core)

Kii pond

C, grab

sample

(top of

sediment)

Kii pond

C, grab

sample

(top of

sediment)

Organophosphate pesticides, bottom material (USGS schedule 1320)

Diazinon μg/kg -- -- -- -- <0 .2 -- -- -- < .4

Ethion μg/kg -- -- -- -- < .2 -- -- -- < .4

Malathion μg/kg -- -- -- -- < .2 -- -- -- < .4

Parathion μg/kg -- -- -- -- < .2 -- -- -- < .4

Parathion-methyl μg/kg -- -- -- -- < .2 -- -- -- < .4

Trithion μg/kg -- -- -- -- < .2 -- -- -- < .4

Organochlorine pesticides, bottom material (USGS schedule 1325)

Aldrin μg/kg -- -- -- -- -- < .3 < .1 < .2 < .2

Chlordane μg/kg -- -- -- -- -- < 3 < 1 < 2 < 2

Dieldrin μg/kg -- -- -- -- -- < .3 < .1 < .2 < .2

Endosulfan μg/kg -- -- -- -- -- < .3 < .1 < .2 < .2

Endrin μg/kg -- -- -- -- -- < .3 < .1 < .2 < .2

Heptachlor μg/kg -- -- -- -- -- < .3 < .1 < .2 < .2

Heptachlor epoxide μg/kg -- -- -- -- -- < .3 < .1 < .2 < .2

Lindane μg/kg -- -- -- -- -- < .3 < .1 < .2 < .2

p,p′-Methoxychlor μg/kg -- -- -- -- -- < .3 < .1 < .2 < .2

Mirex μg/kg -- -- -- -- -- < .3 < .1 < .2 < .2

Perthane μg/kg -- -- -- -- -- < 3 < 1 < 2 < 2

Polychlorinated biphenyls μg/kg -- -- -- -- -- < 3 < 1 < 2 < 2

Polychlorinated

napthalenes

μg/kg -- -- -- -- -- < 3 < 1 < 2 < 2

p,p′-DDD μg/kg -- 0.1 .3 .3 -- < .3 < .1 < .2 < .2

p,p′-DDE μg/kg -- .4 .7 .5 -- < .3 < .1 < .2 < .2

p,p′-DDT μg/kg -- -- .3 .2 -- < .3 < .1 < .2 < .2

Toxaphene μg/kg -- -- -- -- -- < 30 < 10 < 20 < 20

Triazine herbicides, dissolved (USGS schedule 1379)

Alachlor μg/kg -- -- -- -- < .05 -- -- -- --

Ametryn μg/kg -- trace trace -- < .05 -- -- -- --

Atrazine μg/kg -- -- -- -- < .05 -- -- -- --

Cyanazine μg/kg -- -- -- -- < .2 -- -- -- --

Desethylatrazine μg/kg -- -- -- -- < .05 -- -- -- --

Deisopropylatrazine μg/kg -- -- -- -- < .05 -- -- -- --

Metolachlor μg/kg -- -- -- -- < .05 -- -- -- --

Metribuzin μg/kg -- -- -- -- < .05 -- -- -- --

Prometon μg/kg -- -- -- -- < .05 -- -- -- --

Prometryn μg/kg -- -- -- -- < .05 -- -- -- --

Propazine μg/kg -- -- -- -- < .05 -- -- -- --

Simazine μg/kg -- -- -- -- < .05 -- -- -- --

Bromacil μg/kg trace -- -- -- limit not stated; trace

est. < .01

-- -- -- --

Carboxin μg/kg trace -- -- -- do. -- -- -- --

Diphenamid μg/kg trace -- -- -- do. -- -- -- --

Propachlor μg/kg -- -- -- trace do. -- -- -- --

Simetryn μg/kg trace -- -- -- do. -- -- -- --
Table 23 85

Volatile organic compounds (VOC's), bottom material (custom analysis, USGS laboratory)

1,2-Dibromoethane μg/kg -- -- -- -- < 1 -- -- -- --

1,2,3-Trichloropropane μg/kg -- -- -- -- < 1 -- -- -- --

1,2-Dibromo-3-chloropropaneμg/kg -- -- -- -- < 1 -- -- -- --

Benzene μg/kg -- -- -- -- < 2.3 < 1.3 < 2 < 2.4

Bromoform μg/kg -- -- -- -- < 1 -- -- -- --

Bromodichloromethane μg/kg -- -- -- -- < 1 -- -- -- --

Chloroform μg/kg -- -- -- -- < 1 -- -- -- --

Dibromochloromethane μg/kg -- -- -- -- < 1 -- -- -- --

Ethylbenzene μg/kg -- -- -- -- < 1 -- -- -- --

Toluene μg/kg -- -- 12 -- < 1 < 4 -- -- < 3

Xylene μg/kg -- -- -- -- -- < 1.7 < 1.2 < 1.7 < 2.2

Table 23. Organic compounds in pond-bottom sediments at James Campbell National Wildlife Refuge, Oahu, Hawaii, December

28, 1994 (dry season)--Continued

[Reporting limits varied from sample to sample for some constituents; --, compound not detected and can be considered to be "less than" the reporting limit; <,

less than; trace, compound detected, but at concentration less than the reporting limit; μg/kg, micrograms per kilogram; est., estimated; analyses were performed

by the USGS National Water Quality Laboratory in Denver, Colorado; do., ditto]

Chemical constituent Units

Sample designation Minimum reporting limit

Punamano

north pond

(top of

sediment

core)

Punamano

north pond

(bottom of

sediment

core)

Kii pond

C, grab

sample

(top of

sediment)

Kii pond

D, grab

sample

(top of

sediment)

For all

samples

By individual sample

Punamano

north pond

(top of

sediment

core)

Punamano

north pond

(bottom of

sediment

core)

Kii pond

C, grab

sample

(top of

sediment)

Kii pond

C, grab

sample

(top of

sediment)