Scientific Investigations Report 2008–5034

Prepared in cooperation with the State of Hawaii Department of Transportation

Effects of the H-3 Highway Stormwater Runoff on the Water 

Quality of Halawa Stream, Oahu, Hawaii, 

November 1998 to August 2004

Prepared in cooperation with the State of Hawaii Department of Transportation

Effects of the H-3 Highway Stormwater Runoff on the Water 

Quality of Halawa Stream, Oahu, Hawaii, 

November 1998 to August 2004

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2008–5034

U.S. Department of the Interior

U.S. Geological Survey
FRONT COVER

Photograph of an elevated section of the H-3 Highway. USGS photo by Reuben H. Wolff.
Effects of the H-3 Highway Stormwater 

Runoff on the Water Quality of Halawa 

Stream, Oahu, Hawaii, November 1998 to 

August 2004

By Reuben H. Wolff and Michael F. Wong

Prepared in cooperation with the State of Hawaii Department of Transportation

Scientific Investigations Report 2008–5034

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2008

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Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Wolff, R.H. and Wong, M.F., 2008, Effects of the H-3 highway stormwater runoff on the water quality of Halawa 

Stream, Oahu, Hawaii, November 1998 to August 2004: U.S. Geological Survey Scientific Investigations Report 

2008-5034, 78 p.
iii

Contents

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

Introduction.....................................................................................................................................................2

Purpose and Scope ..............................................................................................................................2

Description of Study Area ...................................................................................................................2

Halawa Drainage Basin..............................................................................................................4

Acknowledgements..............................................................................................................................5

Definitions of Terms Used in this Report...........................................................................................5

Previous Studies ............................................................................................................................................5

Constituents and Sources ............................................................................................................................5

Data-Collection Network..............................................................................................................................7

Methods...........................................................................................................................................................8

Rainfall.....................................................................................................................................................8

Discharge...............................................................................................................................................8

Water Quality.........................................................................................................................................8

Sample Collection and Analysis................................................................................................8

Calculation of Loads and Yields..........................................................................................................9

Statistical Methods for Censored Data..................................................................................10

Quality Assurance......................................................................................................................11

Traffic Data...........................................................................................................................................12

H-3 Stormwater Data Analysis ..................................................................................................................12

Rainfall...................................................................................................................................................12

Discharge.............................................................................................................................................12

Analysis of Water Quality Data.........................................................................................................12

Constituent Concentrations during the Storm of April 20, 2002 .........................................13

Temporal and Spatial Distribution of Samples and Constituents During a Storm...........14

Site Comparison of Water-Quality Data.................................................................................18

Comparison of Wet and Dry Seasons ....................................................................................18

Comparison with State of Hawaii Department of Health Criteria......................................29

Comparison with Data Collected Before and During Highway Construction..................29

Comparisons with Other Studies in Hawaii...........................................................................29

Constituent Concentrations and Storm Characteristics ..............................................................30

Confounding Variables..............................................................................................................30

Storm Characteristics ...............................................................................................................34

Relations among Constituents at Storm Drain C ..................................................................34

Relations among Constituents and Storm Characteristics.................................................36

Suggested Modifications to H-3 Highway Monitoring Program..........................................................40

Grab Sampling.....................................................................................................................................40

Other Suggestions ..............................................................................................................................41

Summary and Conclusions.........................................................................................................................42

References Cited..........................................................................................................................................43
iv

Appendix A....................................................................................................................................................48

Appendix B....................................................................................................................................................53

Appendix C....................................................................................................................................................59

Appendix D....................................................................................................................................................67

Appendix E ....................................................................................................................................................72

Figures

1. Selected stream- and rain-gaging stations and drainage basins in the study area, 

Oahu, Hawaii .................................................................................................................................3

2. Flow-duration curves for Xeriscape Garden and Storm Drain C gaging stations, 

October 1998 to September 2004..............................................................................................13

3. Discharge and sampling times for storm of April 20, 2002, at Storm Drain C ...................14

4. Selected physical properties and constituents measured in water samples collected 

from Storm Drain C during the storm of April 20, 2002..........................................................15

5. Sampling times at all stations for storm of February 14, 2003, based on discharge at 

Storm Drain C ..............................................................................................................................16

6. Boxplots of select constituent concentrations from grab samples collected over the 

entire period of the study ..........................................................................................................19

7. Boxplots of select constituent concentrations from composite samples collected over 

the entire period of the study....................................................................................................22

8. Boxplots of daily loads (A) and yields (B) for select constituents from composite 

samples only, collected over the entire period of the study................................................24

9. Boxplots of nitrite plus nitrate concentrations, collected over the entire period of the 

study, compiled by wet and dry seasons................................................................................27

10. Boxplots of total copper concentrations compiled by wet and dry seasons...................28

11. Boxplots comparing select constituent concentrations from Xeriscape Garden 

and Stadium, collected over the entire period of the study, with data from those sites 

collected before and during construction of the H-3 Highway...........................................31

12. Boxplots comparing select constituent concentrations from Storm Drain C, collected 

over the entire period of the study, with data from: a, Fujiwara (1973) and b, Yamane 

and Lum (1985).............................................................................................................................33

13. Example of the time-series data at Storm Drain C................................................................34

14. Scatter plot displaying the relationship between the duration the storms (DUR) as 

measured by discharge at Storm Drain C and the duration of rainfall (RDUR) as 

determined at the Tunnel rain gage.........................................................................................37

15. Scatter plot displaying the relationship between the antecedent dry period and the 

number of vehicles during that period ....................................................................................37

16. XY scatter plots showing the relation between group A constituent total suspended 

solids and discharge at each station ......................................................................................38

17. XY scatter plots showing the relation between group B constituent total dissolved 

solids and discharge at each station ......................................................................................39

B1. Daily values for discharge at Storm Drain C and Xeriscape Garden and rainfall at 

Tunnel rain gage from October 1998 to September 1999 .....................................................53

B2. Daily values for discharge at Storm Drain C and Xeriscape Garden and rainfall at 

Tunnel rain gage from October 1999 to September 2000 .....................................................54
v

B3. Daily values for discharge at Storm Drain C and Xeriscape Garden and rainfall at 

Tunnel rain gage from October 2000 to September 2001 .....................................................55

B4. Daily values for discharge at Storm Drain C and Xeriscape Garden and rainfall at 

Tunnel rain gage from October 2001 to September 2002 .....................................................56

B5. Daily values for discharge at Storm Drain C and Xeriscape Garden and rainfall at 

Tunnel rain gage from October 2002 to September 2003 .....................................................57

B6. Daily values for discharge at Storm Drain C and Xeriscape Garden and rainfall at 

Tunnel rain gage from October 2003 to September 2004 .....................................................58

Tables

1. Station characteristics and types of samples collected. Stations listed in 

downstream order........................................................................................................................7

2. Number of samples collected at each station and date of sampling event. ....................10

3. Changes in Minimum Reporting Levels (MRL) by the analytical laboratory over the 

study period. ................................................................................................................................11

4. Constituent concentrations and loads at all stations during the storm of 

February 14, 2003. .......................................................................................................................17

5. State of Hawaii water-quality standards specific for streams. ..........................................30

6. List of storm characteristics and storm-characteristic acronyms used in 

this study. .....................................................................................................................................35

7. Descriptive statistics for storm characteristics....................................................................36

A1. Results of rinsate blank analyses for trace-element, nutrient, and other 

determinations for Storm Drain C. ...........................................................................................48

A2. Results of rinsate blank analyses for semivolatile-compound determinations for 

Storm Drain C. .............................................................................................................................49

A3. Results of rinsate blank analyses for trace-element, nutrient, and other 

determinations for Xeriscape Garden.....................................................................................50

A4. Results of rinsate blank analyses for semivolatile-compound determinations for 

Xeriscape Garden.......................................................................................................................51

A5. Results of rinsate blank analyses for trace-element, nutrient, and other 

determinations for Quarantine Station....................................................................................52

C1. Statistical summary of detections and values for selected physical properties and 

constituents measured in grab samples collected at Bridge 8. .........................................59

C2. Statistical summary of detections and values for selected physical properties and 

constituents measured in grab samples collected at Storm Drain C. ...............................60

C3. Statistical summary of detections and values for selected physical properties and 

constituents measured in composite samples collected at Storm Drain C......................61

C4. Statistical summary of detections and values for selected physical properties and 

constituents measured in grab samples collected at Xeriscape Garden.........................62

C5. Statistical summary of detections and values for selected physical properties and 

constituents measured in composite samples collected at Xeriscape Garden. .............63

C6. Statistical summary of detections and values for selected physical properties and 

constituents measured in grab samples collected at Quarantine Station........................64

C7. Statistical summary of detections and values for selected physical properties and 

constituents measured in composite samples collected at Quarantine Station. ............65

C8. Statistical summary of detections and values for selected physical properties and 

constituents measured in grab samples collected at Stadium...........................................66
vi

D1. Geometric means and Hawaii Department of Health criteria for nutrients and total 

suspended solids in grab samples at Bridge 8. ....................................................................67

D2. Geometric means and Hawaii Department of Health criteria for select nutrients, 

total suspended solids, and turbidity at Storm Drain C. ......................................................68

D3. Geometric means and Hawaii Department of Health criteria for select nutrients, 

total suspended solids, and turbidity at Xeriscape Garden.................................................69

D4. Geometric means and Hawaii Department of Health criteria for select nutrients, 

and total suspended solids at Quarantine Station. ..............................................................70

D5. Geometric means and Hawaii Department of Health criteria for select nutrients, 

and total suspended solids at Stadium. ..................................................................................71

E1. Spearman correlation coefficients and associated significance probabilities for 

storm characteristics at Storm Drain C. .................................................................................72

E2. Spearman correlation coefficients and associated significance probabilities for 

the preceding-storm characteristics at Storm Drain C........................................................73

E3. Simple statistics for constituents used in Spearman Rank Correlation from 

Storm Drain C. .............................................................................................................................74

E4. Spearman rank correlation coefficients and associated significance probabilities 

for group-A constituents from Storm Drain C. .......................................................................75

E5. Spearman rank correlation coefficients and associated significance probabilities 

for group-B constituents from Storm Drain C. .......................................................................76

E6. Spearman rank correlation coefficients and associated significance probabilities 

for composite sample constituents and storm characteristics from Storm Drain C.......77
vii

Conversion Factors

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 4,047 square meter (m2

)

square foot (ft2

) 0.09290 square meter (m2)

square mile (mi2

) 2.590 square kilometer (km2) 

Volume

gallon (gal) 3.785 liter (L) 

gallon (gal) 0.003785 cubic meter (m3

) 

million gallons (Mgal) 3,785 cubic meter (m3

)

cubic inch (in3

) 16.39 cubic centimeter (cm3) 

Flow rate

foot per second (ft/s) 0.3048 meter per second (m/s)

cubic foot per second (ft3

/s) 0.02832 cubic meter per second (m3/s)

cubic foot per second per square mile [(ft3

/s)/mi2] 0.01093 cubic meter per second per square kilometer (m3/s)/km2]

gallon per minute (gal/min) 0.06309 liter per second (L/s)

gallon per day (gal/d) 0.003785 cubic meter per day (m3

/d)

gallon per day per square mile [(gal/d)/mi2

] 0.001461 cubic meter per day per square kilometer [(m3/d)/km2]

million gallons per day (Mgal/d) 0.04381 cubic meter per second (m3

/s)

million gallons per day per square mile [(Mgal/d)/

mi2

]

1,461 cubic meter per day per square kilometer [(m3

/d)/km2]

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

Vertical coordinate information is referenced to local mean sea level.

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Altitude, as used in this report, refers to distance above the vertical datum.
This page intentionally left blank
Abstract

Since November 1998, water-quality data have been collected from the H-3 Highway Storm Drain C, which collects 

runoff from a 4-mi-long viaduct, and from Halawa Stream 

on Oahu, Hawaii. From January 2001 to August 2004, data 

were collected from the storm drain and four stream sites 

in the Halawa Stream drainage basin as part of the State of 

Hawaii Department of Transportation Storm Water Monitoring 

Program. Data from the stormwater monitoring program have 

been published in annual reports. This report uses these waterquality data to explore how the highway storm-drain runoff 

affects Halawa Stream and the factors that might be controlling the water quality in the drainage basin.

In general, concentrations of nutrients, total dissolved solids, and total suspended solids were lower in highway runoff 

from Storm Drain C than at stream sites upstream and downstream of Storm Drain C. The opposite trend was observed for 

most trace metals, which generally occurred in higher concentrations in the highway runoff from Storm Drain C than in the 

samples collected from Halawa Stream. The absolute contribution from Storm Drain C highway runoff, in terms of total 

storm loads, was much smaller than at stations upstream and 

downstream, whereas the constituent yields (the relative contribution per unit drainage basin area) at Storm Drain C were 

comparable to or higher than storm yields at stations upstream 

and downstream. Most constituent concentrations and loads in 

stormwater runoff increased in a downstream direction.

The timing of the storm sampling is an important factor 

controlling constituent concentrations observed in stormwater 

runoff samples. Automated point samplers were used to collect grab samples during the period of increasing discharge of 

the storm throughout the stormflow peak and during the period 

of decreasing discharge of the storm, whereas manually collected grab samples were generally collected during the later 

stages near the end of the storm. Grab samples were analyzed 

to determine concentrations and loads at a particular point 

in time. Flow-weighted time composite samples from the 

automated point samplers were analyzed to determine mean 

constituent concentrations or loads during a storm. Chemical analysis of individual grab samples from the automated 

point sampler at Storm Drain C demonstrated the “first flush” 

phenomenon—higher constituent concentrations at the beginning of runoff events—for the trace metals cadmium, lead, 

zinc, and copper, whose concentrations were initially high during the period of increasing discharge and gradually decreased 

over the duration of the storm.

Water-quality data from Storm Drain C and four stream 

sites were compared to the State of Hawaii Department of 

Health (HDOH) water-quality standards to determine the 

effects of highway storm runoff on the water quality of 

Halawa Stream. The geometric-mean standards and the 10- 

and 2-percent-of-the-time concentration standards for total 

nitrogen, nitrite plus nitrate, total phosphorus, total suspended 

solids, and turbidity were exceeded in many of the comparisons. However, these standards were not designed for stormwater sampling, in which constituent concentrations would be 

expected to increase for short periods of time.

With the aim of enhancing the usefulness of the waterquality data, several modifications to the stormwater monitoring program are suggested. These suggestions include (1) the 

periodic analyzing of discrete samples from the automated 

point samplers over the course of a storm to get a clearer 

profile of the storm, from first flush to the end of the receding 

discharge; (2) adding an analysis of the dissolved fractions of 

metals to the sampling plan; (3) installation of an automatic 

sampler at Bridge 8 to enable sampling earlier in the storms; 

(4) a one-time sampling and analysis of soils upstream of 

Bridge 8 for base-line contaminant concentrations; (5) collection of samples from Halawa Stream during low-flow conditions to determine base-line conditions; (6) addition of the 

dissolved fraction of the metals chromium and nickel to the 

sampling plan; (7) elimination of fecal coliform and biochemical oxygen demand (BOD) analyses from the sampling plan; 

and (8) a study to examine the efficiency of the highway street 

sweeping.

Effects of the H-3 Highway Stormwater Runoff on the 

Water Quality of Halawa Stream, Oahu, Hawaii, 

November 1998 to August 2004

By Reuben H. Wolff and Michael F. Wong
2 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

among sites to determine how the H-3 highway Storm Drain 

C affects water quality in the stream, (2) comparing waterquality data with State of Hawaii Department of Health waterquality standards (State of Hawaii Department of Health, 

2000), and (3) comparing water quality in the Halawa Stream 

drainage basin with other highway and urban runoff studies, 

both in Hawaii and elsewhere. In addition, water-quality data 

are presented to show how the constituent concentrations vary 

with the rise and fall of the storm hydrograph. Storm characteristics, including volume of discharge, intensity of rainfall, 

storm duration, number of cars during storm, and number of 

dry days before storm, were evaluated using rainfall, discharge, and traffic data to determine relations between the 

constituent concentrations measured at Storm Drain C and the 

storm characteristics. Finally, suggestions for modifying the 

stormwater monitoring program are made to help improve the 

usefulness of this program for assessing the effects of highway 

runoff on stream water quality and evaluating the effectiveness 

of storm water management procedures. Water-quality data for 

this report were collected between November 17, 1998, and 

August 4, 2004.

This report describes the Halawa drainage basins and the 

methods used for water-quality data collection, and it presents a statistical analysis of the water-quality data collected. 

Data were collected in Halawa (station 16227100) and North 

Halawa (stations 212356157531801, 212353157533001, 

16226200, 16226400) drainage basins (fig. 1); stations are 

referred to by their abbreviated station names throughout the 

report (table 1).

Water-quality data used in the analyses in this report 

have been published in the USGS’s annual water-resources 

data reports for Hawaii for water years 1999 through 2004 

(Hill and others, 2000; Taogoshi and others, 2001; Taogoshi 

and others, 2002; Wong and others, 2004; Teeters and others, 

2005; Shimizu and others, 2005). Water-quality data collected 

for the H-3 monitoring program have been summarized and 

published in USGS open-file reports (Presley, 2001, 2002; 

Young and Ball, 2003, 2004).

Description of Study Area

The study area is located in the leeward part of Oahu 

and is mainly defined by the drainage basin of North Halawa 

Stream (fig. 1). The study area is bounded by the ridge 

between North Halawa Stream and South Halawa Stream Valleys on the south, the topographic crest of the Koolau Range 

on the northeast, the ridge between North Halawa and Kalauao 

Stream Valleys on the north, and Pearl Harbor on the southwest. North Halawa Stream originates near the topographic 

crest of the Koolau Range at an altitude of about 2,600 ft and 

terminates near sea level at the coast.

The Koolau Range is the eroded remnant of the larger 

and younger of the two major shield volcanoes that formed 

the Island of Oahu (Hunt, 1996). Much of the windward (east) 

side of the original Koolau Volcano has been eroded, leaving 

Introduction

The H-3 Highway is a major roadway that crosses the 

Koolau Range on the eastern part of the Island of Oahu, 

Hawaii (fig. 1). Potential effects of construction, such as soil 

erosion and stream sedimentation, which would degrade the 

water quality of streams along the route, were an issue of public concern, and construction began in 1987 only after years 

of environmental evaluation (U.S. Department of Transportation and others, 1987). In 1983, the U.S. Geological Survey 

(USGS), in cooperation with the State of Hawaii Department 

of Transportation (HDOT) and in collaboration with the 

Federal Highway Administration (FHA), began a study to help 

assess water-quality conditions in these streams before, during 

and after highway construction (Wong and Yeatts, 2002; Wong 

and Young, 2001; Wong, 2004).

After the completion of the H-3 Highway in 1998, a 

monitoring program examining the quality of highway runoff 

from the North Halawa Valley highway segment was initiated 

(State of Hawaii Department of Transportation, 2000). The 

purpose of this additional monitoring was to identify the factors that control the quality of highway runoff and to determine if constituents from highway runoff would adversely 

affect the quality of water in Halawa Stream. During 2001 

to 2004, data were collected as part of a National Pollutant 

Discharge Elimination System (NPDES) for the HDOT Storm 

Water Monitoring Program (State of Hawaii Department of 

Transportation, 2000). Data from the Storm Water Monitoring 

Program have been published in annual reports (Presley, 2001, 

2002; Young and Ball, 2003, 2004); these data are used in this 

report to evaluate how the highway storm-drain runoff affects 

Halawa Stream (fig. 1) and the factors that might be controlling the water quality in the drainage basin.

The purpose of the sampling, aside from fulfilling 

requirements for the HDOT NPDES permit, is to determine 

whether highway runoff is adversely affecting the quality 

of water in Halawa Stream. Preliminary analyses have been 

done on an annual basis by a contractor to the HDOT (State 

of Hawaii Department of Transportation, 2002, 2003, 2004). 

However, detailed characterizations of the loadings at each 

site, the differences between types of sampling techniques, 

or the changes in constituent concentrations during a storm 

have not been documented. Additionally, the data set has not 

been compared to water-quality standards using statistical 

methods, nor has it been compared to other water-quality data 

in Hawaii or elsewhere in the United States. Furthermore, no 

studies have been done to determine the factors, such as traffic 

volume, storm intensity, total stream discharge related to the 

storm, and the particular antecedent conditions, that contribute 

to the constituent loadings.

Purpose and Scope

The purpose of this report is to characterize water quality 

in the Halawa Stream drainage basin by (1) comparing data 
157°56' 157°55' 157°54' 157°53' 157°52' 157°51' 157°50' 157°49' 

21°22'21°23'21°24'

21°25'21°26'

#

#

#

# #

0 1 2 3 KILOMETERS0 1 2 3 MILES

212356157531801Bridge 8

WILSON TUNNEL

HALAWA STREAM DRAINAGE BASIN BOUNDARY

TRANS-KOOLAUTUNNEL

212353157533001Storm Drain C

16226200XeriscapeGarden

212428157511201

Tunnel 

Rain Gage

16226400QuarantineStation

16227100Stadium

212304157542201Xeriscape GardenRain Gage H-1 Highway

Likelike Highway

KAN

KOOLAU CREST

EXPLANATION

16226200XeriscapeGarden

#

212428157511201Tunnel Rain Gage212356157531801Bridge 8 #

WATER-QUALITY STATION,STATION NUMBER, AND ABBREVIATED NAME (grab-only sampling)STREAM-GAGING AND WATER-QUALITY STATION,STATION NUMBER, AND ABBREVIATED NAMERAIN GAGE, STATION NUMBER, AND ABBREVIATED NAME

StudyArea

OAHU,HAWAII

PacificOcean

Figure 1. Selected stream- and rain-gaging stations and drainage basins in the study area, Oahu, Hawaii.
4 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

a steep windward slope indented with short, broad, amphitheater-shaped valleys (Hinds, 1925). In contrast, the gentle leeward (west) slope is deeply dissected by long, roughly linear 

valleys. Ridges on the leeward side approximate the original 

morphology of the Koolau volcanic dome (Wentworth, 1943). 

Geology of the study area consists primarily of Koolau Basalt 

that was extruded in numerous gently dipping, thin (less than 

10 ft) flows of lava that are intruded by near-vertical dense 

basaltic dikes near the crest of the present Koolau Range 

(Hunt, 1996). The valley floor of the North Halawa drainage basin is overlain by alluvium derived from erosion of the 

Koolau Range (Takasaki and others, 1969; Izuka, 1992).

The climate of Oahu is warm and humid. Average annual 

temperature near the study area is about 74°F, and monthly 

averages range from 65°F to 84°F (Owenby and Ezell, 1992). 

Temperatures above 95°F and below 50°F are rare on Oahu 

(Blumenstock and Price, 1967). The distribution of rainfall is 

affected by the prevailing northeasterly trade winds and the 

topography of the island. Orographic lifting and cooling of 

marine air masses moving with the trade winds cause heavier 

and more frequent rainfall on the windward side and near the 

crest of the Koolau Range. The highest average rainfall occurs 

about 0.5 to 1 mi leeward of the crest (Wentworth, 1942; 

Mink, 1960). Rainfall varies seasonally, with most rainfall 

falling between November and April. Median annual rainfall 

ranges from 40 to more than 120 in. (Giambelluca and others, 

1986).

The temporal and spatial distributions of streamflow 

are determined almost exclusively by geology and rainfall. 

Streamflow in North Halawa Stream is intermittent and 

is dependent primarily on direct runoff that occurs during 

periods of rainfall. Most infiltrating rainfall in the North 

Halawa Valley percolates to the basal aquifer and does not 

contribute to base flows in the streams located there (Izuka, 

1992). Streamflow is supplemented by the discharge of small 

quantities of ground water from alluvial aquifers that extend 

recession flows only to a minor extent (Izuka, 1992).

Soils in the Halawa drainage basin are classified as 

low permeability, very stony clays of the Kaena series, with 

Kawaihapai clay loam soils near the mouth of Halawa Stream 

(Foote and others, 1972). The majority of the mountainous 

areas within the study area are classified as rough mountainous land, rock land, or rock outcrop (Foote and others, 1972), 

and little information is available on the soils of these areas. 

Vegetation in the North Halawa Valley is representative of 

undisturbed forest in the leeward Koolau Range and includes 

native and introduced species.

Halawa Drainage Basin

The Halawa drainage basin is on the leeward side of the 

crest of the Koolau Range and has a drainage area of 8.90 

mi2 upstream of the Stadium station. Halawa Stream originates at the confluence of North and South Halawa Streams, 

upstream of the Moanalua Freeway, and flows into the East 

Loch of Pearl Harbor (fig. 1). Data collection in the Halawa 

drainage basin was concentrated in the North Halawa Valley. 

The water-quality data collected at the Stadium station, on 

Halawa Stream (fig. 1), were the only data collected outside 

of North Halawa Valley. Between Stadium and Xeriscape 

Garden, the land is developed and consists of a light industrial 

park and residential areas near the Moanalua Freeway and 

H-1 Highway. The H-3 Highway constitutes about 3 percent 

of the drainage area upstream of Stadium station and about 4 

percent of the 4.01 mi2 drainage area of North Halawa Stream 

upstream of Xeriscape Garden.

Before highway construction in North Halawa Valley 

began in November 1987, this drainage basin was undeveloped. The lower valley was used for agriculture from 1850 to 

1947 (Spear, 1990). A major water source, the Halawa Shaft, 

was built by the Honolulu Board of Water Supply in 1940 to 

develop ground water from the basal aquifer. It is located 200 

ft downstream from Xeriscape Garden. Pumping from the 

Halawa Shaft does not affect streamflow at Xeriscape Garden 

(Izuka, 1992). There are no streamflow diversions in the drainage basin except for the temporary channel diversions that 

were related to highway construction. The temporary diversions did not transfer surface water out of the drainage basin. 

The Lower North Halawa Valley is deeply incised, with only 

a few small ephemeral tributaries. The stream channel in the 

lower valley is cut about 3 to 6 ft into the alluvium that forms 

the valley floor. The steep, upper part of North Halawa Valley 

is less deeply incised and consists of a dendritic drainage pattern with several intermittent tributaries. In the upper part of 

the drainage basin, channels are cut into bedrock and include 

several waterfalls. The stream is more than 100 ft above the 

basal water table throughout the valley (Izuka, 1992), and flow 

in the main channel is intermittent in most years. About 20 

percent of the stream channel has been channelized, mostly 

upstream of the discharge point of Storm Drain C (Wong and 

Yeatts, 2002).

Most of the highway in the upper valley is raised viaduct, 

designed to minimize effects from highway runoff on the 

ground-water resource of North Halawa Valley. Storm runoff 

from the viaduct is collected and transported through iron 

pipes and aluminum culverts to a discharge point, Storm Drain 

C, in the lower valley. The storm drain collects water from 

about 2.5 miles of twin two-lane viaducts, a total of about 

0.04 mi2

 of concrete area that is isolated from the surrounding 

vegetated land cover. An additional 1.4 mi of highway, part 

viaduct and part on-grade, is located between Storm Drain 

C and Xeriscape Garden. Runoff from this part of the highway discharges in North Halawa Stream as both diffuse and 

smaller point discharges. Total concrete paved area upstream 

of Xeriscape Garden is about 0.06 mi2. There are no entry or 

exit points along the H-3 Highway, so all traffic recorded at 

the Trans-Koolau Tunnels (fig. 1) by the HDOT must travel 

the entire length of the highway. 
Constituents and Sources 5

Acknowledgements

The authors of this report want to thank Ui Byrnes and 

Kyle Oyasato of the State of Hawaii Department of Transportation, who provided the traffic volume data; Todd Presley, 

Marcael Jamison, and Stacie Young of the U.S. Geological 

Survey Pacific Islands Water Science Center (PIWSC), who 

led most of the water-quality sampling, data-entry, and QA/

QC aspects of the study; and Delwyn Oki of the PIWSC for 

his guidance in preparing this report.

Definitions of Terms Used in this Report

Grab sample: a discrete sample collected manually or with 

an automated point sampler with no regard to flow or time; 

instantaneous sample that is analyzed separately.

Flow-weighted composite sample: a blended sample collected 

with an automated point sampler consisting of a mixture of 

aliquots, where the volume of each aliquot is proportional to 

the flow rate of the discharge.

Time composite sample: a blended sample collected with 

an automated point sampler that consists of fixed volume 

aliquots collected at specified time intervals.

Flow-weighted time-composite sample: a blended sample 

collected with an automated point sampler consisting of 

a mixture of aliquots collected at specified time intervals, 

where the volume of each aliquot is proportional to the flow 

rate of the discharge.

Previous Studies

There are a number of investigations from other locations on water-quality of runoff from highways (for example: 

Horner and Mar, 1983; Hoffman and others, 1985; Harned, 

1988; Barrett and others, 1995a; Irish and others, 1995, 1998; 

Tasker and Granato, 2000). These studies have identified 

the constituents that are commonly associated with highway runoff, including nutrients, sediments, organochlorine 

compounds, and trace metals. Some of these studies have 

attempted to identify the factors that affect the water quality 

of highway runoff by regression analysis. Significant factors 

identified include the duration of the runoff, runoff volume, 

runoff intensity, traffic volume both before and during the 

period of runoff, the length of the antecedent dry period, and 

the duration, volume, and intensity of the previous period of 

runoff (Barrett and others, 1995a; Irish and others, 1998). 

Even though traffic volume was not a significant factor for 

all the constituents analyzed by Barrett and others (1995a), 

vehicles, along with atmospheric deposition (Harned, 1988), 

are the major sources of some constituents in highway runoff. 

Vehicles can transport and deposit metals, sulfates, oil and 

grease, particulate matter, and nutrients to highway surfaces 

and runoff. Regression models may be useful tools for identifying constituent-specific factors that affect water quality and 

to predict the quality of highway runoff (Tasker and Granato, 

2000).

Studies on urban stormwater runoff on Oahu from stormdrain systems have been conducted by Fujiwara (1973) and 

Yamane and Lum (1985). Fujiwara (1973) sampled storm 

drains in residential, commercial, and industrial areas in urban 

Honolulu and detected elevated concentrations of suspended 

solids, chemical oxygen demand (COD), fecal coliform, 

nutrients, and lead. Yamane and Lum (1985) sampled residential-area storm drains in central Oahu and found high concentrations of turbidity, suspended solids, total ammonia plus 

organic nitrogen, and total phosphorus in the majority of the 

samples collected. Neither of these two study areas included 

any high-speed highways.

A statistical summary of hydrologic and water-quality 

data collected before, during, and after construction of the H-3 

Highway (October 1982 to September 1989) was presented by 

Wong and Hill (1992). Wong and Young (2001) presented an 

updated statistical summary of hydrologic and water-quality 

data for 1983–99. This summary presented annual rainfall, discharge, suspended-sediment loads and concentrations, particlesize distributions, and water-quality data from discharge and 

suspended-sediment gaging stations.

Constituents and Sources

Most of the material that accumulates on urban roadways 

consists of inert minerals. Stormwater runoff washes this 

material into storm drains and eventually into streams. This 

material has the potential to be harmful to the environment 

because it can transport nutrients, pesticides, organic constituents, and microbial forms that may be sorbed to the sediments 

(Sartor and Boyd, 1972; Irish and others, 1995; Wagner and 

Mitchell, 1987 as cited in Irish and others, 1995).

Determining the sources of the constituents in highway 

runoff is often a complicated matter greatly influenced by 

complex environmental conditions. Constituents can have 

multiple sources, making it difficult to distinguish the dominant source. The accumulation pattern of materials on roadways involves materials continually being blown on and off 

the roadway. Stormwater washes constituents from the road 

surface and from the exteriors and undercarriages of vehicles. 

Periodic roadway cleaning reduces the amount of accumulated 

material. Additionally, biological and chemical processes, 

such as volatilization, chemical decay, and biodegradation, can 

break down and remove constituents (Irish and others, 1995).

Suspended sediment is that portion of the total sediment 

load that is carried in the water column. Particulates and sediment in runoff can also cause problems by decreasing flow 

capacity in drainage ways, reducing storage volume in ponds 

and lakes, smothering benthic organisms, decreasing water 
6 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

clarity, and interfering with the respiration of small fish. Furthermore, toxic materials often are sorbed to and transported 

by suspended solids. These toxic materials include metals, 

hydrocarbons, chlorinated pesticides, and polychlorinated 

biphenyls (PCBs), and they present acute and chronic threats 

to organisms living in or using the water (Barrett and others, 

1995b; Irish and others, 1995).

The concentration of nitrogen and phosphorus in highway runoff is a concern because these compounds stimulate 

the growth of aquatic plants in surface waters, increasing 

the potential for eutrophication and depletion of the oxygen 

required by aquatic organisms (Barrett and others, 1995b; Irish 

and others, 1995). Nutrients in stormwater may be derived 

from both natural and anthropogenic sources. Nitrogen may 

be derived from rainfall, fixation of atmospheric nitrogen by 

plants, fertilizers, human and animal waste, or automobile 

emissions. Phosphate may be derived from volcanic rocks, 

continental dust, or fertilizers. Because phosphate is retained 

by minerals common in Hawaiian soils, total phosphorus 

concentrations in stormwater runoff commonly increase 

with increasing suspended-sediment concentrations (Hoover, 

2002; DeVito and others, 1995; Yim and Dugan, 1975). Thus, 

unpaved areas may represent a main source of some nutrients 

in stormwater runoff. Riparian buffer zones along streams 

help to reduce effects of runoff, and the loss of riparian buffer 

zones can lead to increased nutrient and sediment problems 

(Laws and Ferrentinos, 2003).

Research in Hawaii has shown that trace metals, including lead, cadmium, zinc, and copper are transported into 

streams and estuaries as a result of soil erosion (Sutherland, 

2000; De Carlo and Spencer, 1995; De Carlo and Spencer, 

1997; De Carlo and Anthony, 2002; Andrews and Sutherland, 

2004; Beltran and De Carlo, 2005; De Carlo and others, 2005). 

Vehicles are considered to be the primary source of anthropogenic trace-metal inputs by way of emissions, wear and 

tear, brake linings, and vehicle fluids or lubricants. Secondary sources include leaded paints and agricultural and industrial inputs (Sutherland, 2000; Sutherland and others, 2003). 

Naturally occurring trace metals in the soils and geologic 

formations of Hawaii have been investigated using isotoperatio data to determine baseline trace-metal concentrations. 

Naturally occurring lead from geological deposits in east Oahu 

are low—less than 10 mg/kg (Sutherland and others, 2003). 

De Carlo and Spencer (1997) stated that naturally occurring 

lead concentrations in soils in Hawaii rarely are above 40 mg/

kg and are usually much lower, with the highest concentrations occurring in a few basins where the soils are enriched 

with lead by local geological and hydrological conditions. 

Sediment concentrations of the trace metals aluminum, cobalt, 

iron, manganese, and nickel are primarily controlled by natural 

source variations, whereas other trace metals such as copper, zinc, and lead are influenced by anthropogenic activities 

(De Carlo and Spencer, 1997; Sutherland and others, 2000; 

De Carlo and Anthony, 2002; De Carlo and others, 2004; De 

Carlo and others, 2005).

The introduction of alkyl-lead fuel additives in 1923 has 

been identified as a major anthropogenic contributor of lead 

input to the atmosphere in Hawaii (Chow and Earl, 1972; 

De Carlo and Spencer, 1995; De Carlo and Spencer, 1997; 

Sutherland and others, 2000; Sutherland and Tolosa, 2000; De 

Carlo and Anthony, 2002). Leaded gasoline was the source 

of an estimated 450 tons of lead released in Hawaii in 1971 

alone (Eshelman, 1973). The use of alkyl-lead additives was 

restricted in Hawaii by legislation starting in 1975, but it was 

not entirely eliminated in Hawaii until 1989, according to 

the State of Hawaii Department of Business and Economic 

Development records (De Carlo and Spencer, 1997). Before 

the 1975 legislation, Jernigan and others (1971) reported that 

the average urban curbside atmospheric concentrations of lead 

in and around urban Honolulu, Hawaii, was 0.0077 μg/L, with 

the highest curbside atmospheric concentration of lead, 0.0235 

μg/L, found at the Wilson Tunnel (fig. 1).

De Carlo and Spencer (1997) determined that the 

distribution of lead in bed sediment cores from the Ala Wai 

Canal paralleled the use of alkyl-lead fuel additives on Oahu. 

Anthropogenic sources accounted for more than 90 percent of 

the lead in some sediment core intervals. An analysis of the 

stable lead isotope ratios indicated that the lead in the sediment cores was distinct from natural sources. Anthropogenic 

activity was also determined to be the source of the trace metals cadmium, copper, and zinc (De Carlo and Spencer, 1997). 

Beltran and De Carlo (2005) observed that during storms in 

the urban Ala Wai Canal Watershed, particulate lead, zinc, 

copper, barium, and cobalt had elevated concentrations and 

particulate loads. DeCarlo and others (2004) also noted that 

the highest concentrations of trace elements occurred during 

the “first flush,” the early stages of the hydrograph before 

peaks in discharge, for particulate lead, zinc, and copper and 

to a lesser degree for barium and cobalt.

Road-deposited sediment in the Manoa basin in leeward 

Oahu was examined by Sutherland and Tolosa (2000). They 

determined that the road-deposited sediment had a significant amount of lead, antimony, and zinc that were attributed 

to vehicles and the past use of leaded gasoline. These sediments are transported into Manoa Stream, where elevated 

concentrations have been found in bed sediments and fish 

tissue (Andrews and Sutherland, 2004; Brasher and Anthony, 

2000; Brasher and Wolff, 2004; De Carlo and others, 2005; 

Schmitt and Brumbaugh, 1990; Sutherland, 2000). Sutherland 

and others (2003), using isotope ratios, determined that the 

erosion of roadside soils contaminated with lead from the past 

use of leaded gasoline was the major contributor of lead to the 

present-day road sediments.

Legacy contaminants, those contaminants that continue 

to persist in the environment although they are no longer in 

use, have been shown to be related to both past and present 

land use in a watershed (Nowell and others, 1999). The use 

of organochlorine pesticides for agriculture and urban pest 

control was widespread from the mid-1940s to the mid1980s (Wong and others, 2000; Brasher and Anthony, 2000). 

Although these pesticides were largely banned in the United 
Data-Collection Network 7

States in the 1970s and 1980s, they continue to persist in the 

soils. Studies in Hawaii have shown that concentrations of 

certain organochlorine pesticides such as chlordane and dieldrin continue to be among the highest in the nation (Bevenue 

and others, 1972; Tanita and others, 1976; Schmitt and others, 

1981, 1985; Schmitt and Brumbaugh, 1990; Hunter and others, 1995; Brasher and Anthony, 2000). Considerable amounts 

of pesticides, including chlordane, aldrin, dieldrin, and heptachlor, were used in Hawaii to control termites (Brasher and 

Wolff, 2004). 

Industrial compounds such as polychlorinated biphenyls 

(PCBs) and other semivolatile organochlorines (SVOCs) are 

extremely persistent anthropogenic organic compounds (Smith 

and others, 1988; Lopes and Furlong, 2001). PCBs, while 

no longer produced in the United States, are still found in 

transformers and capacitors (Smith and others, 1988). Other 

SVOCs are commonly used in a variety of industrial products 

and are widespread in the environment. SVOCs include phthalates, phenols, and polycyclic aromatic hydrocarbons (PAHs). 

PAHs are produced during incomplete combustion and commonly occur in vehicle exhaust and waste incinerators (Lopes 

and Furlong, 2001; Brasher and Wolff, 2004).

Data-Collection Network

Stream-stage, stream-discharge, rainfall, and waterquality data were collected at selected stations in the Halawa 

Stream drainage basin (table 1). Rainfall data were collected 

at the Tunnel rain gage and the Xeriscape Garden rain gage. 

Continuous discharge data have been collected at three stations 

in North Halawa Valley since 1998, 1983, and 2001, respectively, for Storm Drain C, Xeriscape Garden, and Quarantine 

Station. These stations are equipped with automated point 

samplers. The Quarantine station was put into service on 

July 10, 2001, destroyed on December 7, 2003, and rebuilt in 

June 2005. Rainfall and discharge data were collected using 

variable time steps, depending on rainfall or discharge rates. 

Data from the two rain gages and the discharge gaging stations 

are transferred daily to the USGS National Water Information System (NWIS) database using cellular-phone telemetry 

and can be viewed at http://hi.water.usgs.gov/ by selecting the 

appropriate USGS station numbers.

Water-quality data were collected at five stations (fig. 

1): Bridge 8; Storm Drain C; Xeriscape Garden; Quarantine station; and Stadium. The Bridge 8 station is about 0.75 

mi upstream from the discharge point of Storm Drain C on 

North Halawa Stream. Storm Drain C collects runoff from an 

approximately 2.5-mi length of freeway, starting at the leeward 

Tetsuo Harano (Trans-Koolau) tunnel portal and extending to 

mid-valley, and discharges directly to North Halawa Stream 

(fig. 1). The Xeriscape Garden station is directly upstream 

from a light-industrial area near North Halawa Stream and 

about 1.48 mi downstream of the discharge point of Storm 

Drain C. The Quarantine station is about 1 mi downstream of 

Xeriscape Garden and near the downstream end of the lightindustrial area that borders the North Halawa Stream. The 

Stadium station is about 1.5 mi downstream of the Quarantine 

station, below the confluence of North and South Halawa 

Streams, downstream from the crossing of H-1 freeway, and 

directly upstream from the mouth at Pearl Harbor. Discharge 

peaks from Storm Drain C occur about 60 to 90 minutes 

before peaks at Xeriscape Garden when the stream is flowing. When the stream is dry before a storm, peaks from Storm 

Drain C can occur about 6 hours before peaks at Xeriscape 

Garden. Available water-quality data can be viewed at http://

waterdata.usgs.gov/hi/nwis/qwdata by selecting the appropriate USGS station numbers.

Table 1. Station characteristics and types of samples collected. Stations listed in downstream order.

[Horizontal datum for latitude and longitude coordinates is Old Hawaiian; mi2, square miles; na, not applicable; N., North; numbers in parentheses are the State 

key numbers]

USGS Station 

Number Station Name Abbreviated station name

Latitude Longitude Drainage Area

(mi2

)

Types of samples

collected

212428157511201 N. Halawa Valley Rain Gage 

at tunnel (771.11)

Tunnel rain gage 21°24ʹ28ʺ 157°51ʹ12ʺ na na

212356157531801 N. Halawa Stream at Bridge 

8 near Halawa

Bridge 8 21°23ʹ56ʺ 157°53ʹ18ʺ 3.17 Grab Only

212353157533001 N. Halawa Valley, Storm 

Drain C near Aiea

Storm Drain C 21°23ʹ53ʺ 157°53ʹ30ʺ 0.04a Grab and Composite

16226200 N. Halawa Stream near 

Honolulu

Xeriscape Garden 21°23ʹ04ʺ 157°54ʹ22ʺ 4.01 Grab and Composite

212304157542201 N. Halawa Rain Gage near 

Honolulu (771.9)

Xeriscape Garden

rain gage

21°23ʹ04ʺ 157°54ʹ22ʺ na na

16226400 N. Halawa Stream near 

Quarantine station at 

Halawa

Quarantine Station 21°22ʹ28ʺ 157°54ʹ59ʺ 4.68 Grab and Composite

16227100 Halawa Stream below H-1 Stadium 21°22ʹ17ʺ 157°55ʹ57ʺ 8.9 Grab Only

a

 Estimated area of elevated highway from Trans-Koolau Tunnel to storm drain.
8 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

Methods

This section describes the methods used to collect and 

process discharge data, rainfall data, water-quality samples, 

traffic data, and the quality-control (QC) measures used in the 

study.

Rainfall

Rainfall was recorded at two stations using a standard 

8-in. National Weather Service collector attached to a 7 

5/16-in. rain can with float-type recorder system. The floattype rain gages were put into service in May 1983 at the Xeriscape Garden rain gage and in July 1998 at the Tunnel rain 

gage. A float-type gage records continuous change in rainfall 

volumes that are captured in a storage can connected to the 

8-in. rain collector.

Discharge

Direct measurements of discharge were made periodically at all stream-gaging and stream water-quality stations 

using standard practices (Rantz and others, 1982). Peak flows 

that could not be measured with current meters were measured 

using the slope-area method (Dalrymple and Benson, 1968) or 

using float measurements (Buchanan and Somers, 1969: Rantz 

and others, 1982). Data were computed using the discharge 

measurements and water level or stage recorded at each of the 

stations as described by Rantz and others (1982). Total annual 

discharge is determined by summing the daily mean values of 

discharge for the water year.

Water Quality

Water-quality samples obtained during January 1998 to 

September 2004 were collected using techniques described in 

Young and Ball (2005). Five water-quality sampling stations 

in the Halawa drainage basin were used for this study: Bridge 

8, Storm Drain C, Xeriscape Garden, Quarantine Station, and 

Stadium (fig. 1). The Bridge 8 site is located upstream of the 

discharge point of Storm Drain C, and the Xeriscape Garden, 

Quarantine Station, and Stadium sites are downstream of the 

discharge point of the storm drain. The Quarantine Station and 

Stadium sites are located within a light-industrial and urban 

area and also receive runoff from the highway downstream 

from Storm Drain C. Storm Drain C, Xeriscape Garden, and 

the Quarantine Station sites are equipped with automated point 

samplers. 

Sample Collection and Analysis

Measurements of discharge, water temperature, specific 

conductance, pH, and dissolved oxygen were made in the 

field. Additionally, samples were collected and analyzed for 

turbidity, total suspended solids (TSS), major ions, nutrients, 

trace metals, and organic constituents such as total organic 

carbon (TOC), oil and grease, pesticides, herbicides, and polychlorinated compounds. All field measurements and samples 

for chemical constituent analyses were collected, processed, 

and treated according to guidelines in Ward and Harr (1990), 

Sylvester and others (1990), and Shelton (1994). 

Samples collected before the beginning of the NPDES 

sampling program in 2001 were primarily grab samples 

collected manually or with the automated point samplers at 

Storm Drain C and Xeriscape Garden. Grab samples were 

collected manually using isokinetic, depth-integrating samplers and equal-width increment (EWI) techniques when flow 

conditions (stream widths greater than 3 ft and depths greater 

than 0.5 ft) permitted. Otherwise, single vertical sampling 

techniques were used at the centroid of streamflow. Samples 

for inorganic analysis were collected using a DH-81 sampler 

with 1-liter polyethylene bottles when depths were greater 

than 0.5 ft. An open-mouth polyethylene bottle was used to 

collect samples from shallower depths. A churn splitter (Ward 

and Harr, 1990) was used to composite and split samples for 

inorganic analysis.

Each automatic sampler collected water from a fixed 

point in the stream channel after predetermined stage thresholds were met. The automatic samplers had a capacity of 24 

bottles and were programmed to collect over various time 

intervals. Sampling before 2001 was conducted with no strict 

guidelines; the intent was to explore possible contaminant 

concentrations within the stream and storm drain with respect 

to the recently opened highway viaduct.

Samples collected for the NPDES program included 

grab samples, collected using manual techniques and/or the 

automatic sampler at the five sites, and flow-weighted, timecomposite samples, collected at the three sites with automatic 

samplers. The composite sample was created by combining 

volumes from each sample bottle proportional to the stream 

discharge volume between the sample-collection times. 

Flow-weighted, time-composite samples were collected over 

a period that sometimes lasted several hours. A consistent 

set of analyses, including constituent analyses for four trace 

metals (copper, zinc, cadmium, and lead), a NPDES nutrient 

schedule, TDS and TSS, COD, oil and grease, and a few other 

analyses, was used for each sample.

A mean discharge was calculated for each composite 

sample. The mean discharge was equal to the total volume 

of water that passed by the gaging station during sample 

collection, divided by the total elapsed time during sample 

collection, using the data from only the samples used for the 

composite. To determine the total volume, the discharge at the 

time of sample collection was multiplied by the elapsed time 

since the previous sample was collected. The same time increment between the first and second samples was also assigned 

to the first sample. These volumes were summed, and the total 

volume was divided by the sum of all the time increments.

The DOT Stormwater Monitoring Program Plan (State of 

Hawaii Department of Transportation, 2000) states that water-
Methods 9

quality samples will be collected at least once per quarter during periods of storm runoff from each of the five water-quality 

monitoring stations (fig. 1). Grab samples are to be collected 

during the period of increasing discharge of the storm whenever possible to characterize the first flush. In practice, this 

was difficult to accomplish except for sites with automated 

point samplers. The plan also states that efforts will be made 

to sample all five water-quality monitoring stations during the 

same storm, and if a storm does not occur during a quarter, no 

samples will be collected for the quarter.

A complete set of samples for a storm consisted of five 

grab samples (one from each of the five stations), three flowweighted time-composite samples, and one quality-assurance 

and quality-control (QA/QC) sample. However, some storms 

were brief and did not produce adequate runoff to sample all 

five stations for both inorganic and organic analysis. In practice, these storms have been sampled as thoroughly as possible and analyzed for an assortment of constituents. Several 

storms, however, lasted for two to three days (table 2). A total 

of 9 storms were sampled at all five stations, while the rest of 

the approximately 29 storms were sampled at some combination of one to four sites. Even though the HDOT Stormwater 

Monitoring Program Plan required only one QA/QC sample to 

be collected per storm, three QA/QC samples were collected 

in previous years and considered part of a complete storm 

sample. Since December 2003, however, the number of QA/

QC samples was reduced to the required one sample per storm 

(Young and Ball, 2005).

The U.S. Environmental Protection Agency’s (USEPA) 

Storm Water Sampling Guidance Manual (U.S. Environmental 

Protection Agency, 1993) provides guidelines for stormwatersampling criteria. The first criterion requires at least 0.1 in. of 

accumulated rainfall. Rainfall accumulations exceeded 0.1 in. 

at both rain gages when stormwater sampling was conducted. 

The second criterion requires that samples be collected only 

for storms preceded by at least 72 hours of dry weather. The 

second criterion would prevent sampling of most storms on 

North Halawa Stream because the Halawa Stream drainage 

basin, as well as many other parts of Oahu, receives tradewind 

showers almost daily (Blumenstock and Price, 1967). Instead, 

the criteria used to initiate sampling of the stream and storm 

drain were based on the rate of rainfall accumulation and the 

rise of stage in Storm Drain C and at Xeriscape Garden stations. Each automatic sampler was triggered at predetermined 

station-specific stream-stage thresholds (3 cfs for Storm Drain 

C and 40 cfs for Xeriscape Garden).

The methods used for the analyses of all the water-quality 

properties and constituents followed those in Wershaw and 

others (1987), Britton and Greeson (1989), Fishman and Friedman (1989), and Fishman (1993). All laboratory analyses were 

conducted by the U.S. Geological Survey’s National Water 

Quality Laboratory (NWQL) in Colorado. Quality control 

practices at NWQL are documented in Friedman and Erdmann 

(1982) and in Pritt and Rease (1992). In January 1993, laboratory analysis for total nitrate and nitrite was discontinued and 

only dissolved nitrate and nitrite were analyzed after that date, 

because values for total and dissolved nitrate and nitrite were 

statistically indistinguishable (U.S. Geological Survey Office 

of Water Quality Technical Memorandum 93.04). Samples 

were analyzed for trace metals by ICP-AES (Inductively 

Coupled Plasma - Atomic Emission Spectrometry) from 1983 

to 1998, then GFAA (Graphite Furnace - Atomic Adsorption) 

from 1998 to 1999, and then ICP-MS (Inductively Coupled 

Plasma - Mass Spectrometry) from 2000 to present. Samples 

were analyzed for organic compounds by GC/MS (Gas Chromatography/Mass Spectrometry).

Calculation of Loads and Yields

The analysis of the storm runoff data differs from previous USGS H-3 Highway reports because the purpose of this 

study was to determine the effects of the operation of the 

H-3 Highway on North Halawa Stream water quality. The 

approach in this report used data from automatic water-quality 

samplers as well as manual grab samples collected during 

storms, especially those storms with sufficient rainfall to 

cause high discharge at the Xeriscape Garden station, in order 

to compare water quality from the highway runoff to waterquality criteria and to determine the factors contributing to the 

highway runoff.

Instantaneous constituent loads for all analyses are 

reported in pounds per day (lbs/day) and were calculated as 

the product of the constituent concentration (Event Mean Concentration (EMC) for composite samples) multiplied by the 

associated discharge (instantaneous for discrete samples, event 

mean for composite samples) and the appropriate conversion 

factor using the equation:

L = Q x C x K (1)

(Terrio, 1995; East and others, 1998; Sneck-Fahrer and others, 

2005) where:

L = constituent load in pounds per day, 

Q = discharge, in cubic feet per second,

C = constituent concentration, in milligrams 

per liter or micrograms per liter, and

K = conversion factor.

Instantaneous constituent yields are reported in pounds 

per square mile per day and were calculated using the equation:

Y = L/DA (2)

where:

Y = constituent yield, in pounds per square 

mile per day,

L = constituent load, in pounds per day, and

DA = area of contributing drainage basin, in 

square miles.
10 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

Storm loads were calculated using equation 1 by replacing the instantaneous discharge and concentration values with 

the event mean discharge and concentration values for the 

storm of interest. Storm yields were calculated using equation 2 by replacing the instantaneous constituent load with 

the storm constituent load. The event mean discharge is equal 

to the total volume of water that flowed by the gaging station 

during sample collection, divided by the total elapsed time 

required to collect the samples. The event-mean concentration 

(EMC) was used whenever more than one sample was collected for a storm event. The EMC is the constituent concentration determined by analyzing a flow-weighted composite 

sample or by weighting the concentration data from multiple 

grab samples collected over various times of a storm by the 

storm volume, as shown in equation 3:

EMC = (CiVi + CjVj +.... + CnVn) / VOL (3)

where:

CiVi = the concentration at a specific time 

multiplied by the flow volume (V) during 

the time interval beginning one-half way 

between i and the time of the previous 

sample or beginning of a storm and ending 

half way between i and the time of the 

next sample or end of the storm. There 

were times when only one sample set was 

collected during a storm. In such cases, the 

concentration values from this one set were 

used as the EMC.

Statistical Methods for Censored Data

Water-quality data are often reported as less than the analytical laboratory minimum reporting level (MRL), defined as 

the smallest measured concentration of a constituent that may 

be reliably reported using a given analytical method (Timme, 

1995; Childress and others, 1999). These results are reported 

with a remark code ‘<’, indicating the actual value is known to 

be less than the value shown. This means that the actual result 

can range anywhere from zero up to the MRL, but cannot be 

known with certainty. Therefore, a value reported as less than 

the MRL does not necessarily mean that the constituent is not 

present in the sample. It may be absent or may be present at a 

concentration below the reporting level currently in use by the 

laboratory. 

Reporting levels can be increased or decreased over time 

because of improved sampling and laboratory techniques 

or greater understanding of the analytical methods involved. 

Results can also be reported as estimated values (remark code 

‘E’). Some MRL changes at the NWQL during the course of 

this study are listed in table 3. More information regarding 

analytical detection limits can be found in Childress and others (1999). Constituents with multiple detection limits were 

analyzed in this report using the detection limit applicable at 

the time the samples were originally collected. 

Table 2. Number of samples collected at each station and date of 

sampling event.

[–, no samples; dates in italics indicate storm sampling continued from 

previous day; includes grab and composite samples]

Date Bridge 8 Storm 

Drain C

Xeriscape 

Garden

Quarantine

Station Stadium

17-Nov-98 – – 1 – 1

18-Nov-98 – 1 4 – –

2-Mar-99 – – 1 – –

6-Jun-99 – 1 – – –

9-Jun-99 – 1 – – –

15-Jun-99 – 1 – – –

16-Oct-99 – 2 – – –

19-Oct-99 – 5 4 – –

20-Oct-99 – – 1 – –

4-Nov-99 – 6 9 – –

7-Nov-99 – 1 – – –

9-Nov-99 – 1 – – –

11-Nov-99 – 1 – – –

30-Nov-99 – 1 – – –

1-Dec-99 – 1 5 – –

13-Jan-00 – 2 – – –

26-Jan-00 – 4 1 – –

23-Mar-00 – 1 – – –

25-Mar-00 – 1 – – –

26-Mar-00 – 2 – – –

27-Mar-00 – 2 1 – –

31-Mar-00 – – 4 – –

7-Jun-00 – 1 – – –

31-Jul-00 – – 1 – –

20-Aug-00 – – 4 – –

5-Jun-01 1 1 1 1 1

16-Sep-01 1 2 2 1 1

28-Oct-01 1 1 2 1 1

26-Jan-02 – 2 2 1 –

28-Jan-02 – 1 1 – –

29-Jan-02 1 1 1 2 1

20-Apr-02 – 8 1 3 –

5-May-02 – 1 1 1 –

6-May-02 1 1 1 1 1

14-Oct-02 – 1 – – –

15-Oct-02 – 1 1 1 –

15-Jan-03 – 2 – – –

30-Jan-03 – 1 – – –

31-Jan-03 1 2 2 2 1

14-Feb-03 1 2 2 2 1

16-Mar-03 – 1 1 1 –

17-Mar-03 – – 1 1 –

26-Jul-03 1 2 2 1 –

29-Nov-03 1 2 4 3 –

22-Jan-04 – 1 2 – –

23-Jan-04 – – 1 – –

25-Jan-04 – 1 1 – –

26-Feb-04 – 2 1 – –

27-Feb-04 1 1 1 1 1

3-Aug-04 – 1 – – –

4-Aug-04 1 1 1 1 1
Methods 11

Methods for computing summary statistics, including mean, standard deviation, and geometric mean, for data 

reported as less than the MRL are summarized in Helsel 

(1990, 2005). The method recommended by Helsel (2005) 

for computing means is the robust approach to “regression on 

order statistics” (Robust ROS), also called the log-probability 

regression method (Gilliom and Helsel, 1986; Helsel and 

Gilliom, 1986) and extended for multiple detection limits in 

Helsel and Cohn (1988). This method is suitable for small 

to moderate sized datasets, multiple detection limits, and 

non-normally distributed data, and it avoids transformation 

bias where logarithmic summary statistics are re-transformed. 

Individual censored values are estimated by first fitting the 

log-transformed detected values to a regression equation. Censored values are predicted from the regression equation on the 

probability plot on the basis of their normal scores. These estimated values are then back-transformed to the original units, 

substituted into the dataset, and used for the limited basis of 

calculating the summary statistics. This method is explained 

fully in Helsel (2005) and Shumway and others (2002). The 

Robust-ROS estimates were calculated with a SAS macro 

modified by Helsel and available on the World Wide Web at 

http://www.practicalstats.com/Pages/software.html using SAS/

STAT® software, Version 9.1 of the SAS System for Windows, copyright© 2002-2003 by SAS Institute, Inc.

Quality Assurance

Field and laboratory quality-assurance (QA) and qualitycontrol (QC) procedures were implemented as described in the 

DOT Storm Water Monitoring Program Plan (State of Hawaii 

Department of Transportation, 2000). The automatic-sampler 

Table 3. Changes in Minimum Reporting Levels (MRL) by the analytical laboratory over the study period.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property; Start date, date that the reporting level went into effect; End 

date, date the reporting level was superseded; ESP, end of the study period; mg/L, milligrams per liter; mg/L, micrograms per liter]

Constituent name USGS parameter 

code Start date End date Minimum Reporting Level Units

Nitrogen, nitrite, dissolved 00613 13-Oct-94 3-Oct-00 0.01 mg/L

4-Oct-00 14-May-01 0.006 mg/L

1-Oct-01 ESP 0.008 mg/L

Phosphorus, dissolved 00666 21-Jan-99 3-Oct-00 0.05 mg/L

15-May-01 30-Sep-02 0.06 mg/L

1-Oct-03 ESP 0.04 mg/L

Total phosphorus 00665 1-Oct-98 20-Jan-99 0.05 mg/L

4-Oct-00 14-May-01 0.06 mg/L

1-Oct-02 ESP 0.04 mg/L

Total suspended sediment 00530 1-Jan-92 31-Mar-00 1 mg/L

1-Apr-00 ESP 10 mg/L

Oil and grease 00556 23-Jul-96 30-Sep-01 1 mg/L

1-Oct-01 ESP 7 mg/L

Nitrogen, ammonia, dissolved 00608 14-Nov-97 3-Oct-00 0.02 mg/L

1-Oct-03 ESP 0.04 mg/L

Nitrogen, nitrite + nitrate 00631 14-Oct-94 3-Oct-00 0.05 mg/L

1-Oct-02 ESP 0.06 mg/L

Total cadmium 01027 8-Feb-00 7-Nov-00 1 mg/L

1-Oct-03 30-Sep-06 0.04 mg/L

Chromium, dissolved 01030 1-Jan-92 30-Sep-99 1 mg/L

15-May-01 30-Sep-05 0.8 mg/L

Nickel, dissolved 01065 1-Jan-92 30-Sep-99 1 mg/L

1-Oct-99 17-Oct-00 1.4 mg/L

Total nickel 01067 1-Jan-92 30-Sep-99 1 mg/L

1-Oct-99 14-May-01 1.8 mg/L

Total zinc 01092C 1-Oct-99 14-May-01 31 mg/L

01092D 8-Feb-00 30-Sep-02 1 mg/L

1-Oct-02 ESP 2 mg/L
12 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

intake lines were routinely cleaned. To confirm that the 

sampling equipment was effectively cleaned, rinsate blanks, 

using inorganic blank water (IBW), were collected from the 

automatic samplers after cleaning the intake lines. Additional 

rinsate samples were periodically collected from the DH-81 

isokinetic sampler after cleaning and from the Teflon® bottle 

liner used in the automatic samplers. The rinsate blanks were 

analyzed for nutrients and for cadmium, copper, lead, and 

zinc. All grab-sample collection equipment was cleaned before 

each storm and sampling.

With regard to potential cross-contamination in the intake 

lines, it is important to note that the automatic sampler pumps 

a rinse cycle before every sample collected. Water is first 

purged, then sucked up the line to a sensor located before the 

sample bottles, and finally purged before the sample is collected. After the sample is collected, the line is purged again. 

The purge, rinse, purge, sample collection, and third-purge 

cycle minimizes possible contamination from water pumped 

during earlier storms and from previously pumped samples 

during the same storm.

The results of the rinsate blank analyses for the automatic samplers at Storm Drain C, Xeriscape Garden, and 

Quarantine Station are provided in appendix A. The most 

noteworthy information provided by the rinsate blank analyses 

are the results for total zinc. Concentrations of total zinc were 

reported above the minimum reporting level (1 μg/L before 

October 2002; 2 μg/L beginning in October 2002) in 67 percent (14 out of 21) of the QA samples collected between April 

2, 2001, and September 8, 2004. The highest zinc concentration of 27 μg/L was reported on July 15, 2003 at Storm Drain 

C. The high concentrations of zinc in the blank samples need 

to be considered when interpreting the storm sampling analytical results of zinc (Office of Water Quality Technical Memorandum 2001.02).

Traffic Data

The bidirectional, hourly traffic-volume data provided 

by the HDOT of all vehicles passing through the Tetsuo 

Harano (Trans-Koolau) tunnel exhibited a consistent pattern of 

highway use. Weekends and holidays were characteristically 

unimodal, with a single peak around midday. Non-holiday 

weekdays were characteristically bimodal, with two peaks 

representative of the morning and evening rush hours. Large 

storms tended to reduce or delay highway vehicular usage. 

Traffic on Hawaii’s roadways has increased as the resident 

population of Honolulu County has increased from 875,377 in 

2000 to 899,562 in 2004 (U.S. Census Bureau, 2007) and the 

number of registered motor vehicles in Honolulu County has 

increased from 614,985 in 2000 to 688,163 in 2004 (State of 

Hawaii Department of Business, Economic Development and 

Tourism, 2005). A street-sweeping schedule was not available 

at the time of this report.

H-3 Stormwater Data Analysis

Rainfall

Rainfall records for this study spanned from 1999 to 2004 

at both rain gages. Annual rainfall totals were approximately 

four times greater at the Tunnel rain gage than at the Xeriscape 

Garden rain gage, except in 2004, when it was only approximately two times greater. This marked difference highlights 

the localized difference in rainfall between the leeward mountain slopes and the leeward lowlands, as discussed in Blumenstock and Price (1967). The lowest annual rainfall totals were 

in water year 2001, and the highest were in water year 2004. 

Discharge

Storm Drain C drains only the surface area of the elevated 

H-3 highway and only flows during periods of rainfall. Flow 

at Storm Drain C during the 6-year study period averaged 0.18 

cfs and exceeded 1.0 cfs less than 10 percent of the time (fig. 

2). The Xeriscape Garden station on North Halawa Stream has 

a much larger drainage area and therefore higher flows. The 

average discharge at the Xeriscape Garden station was 4.2 cfs 

during the 6-year study period (fig. 2). Both Storm Drain C 

and Xeriscape Garden stations had periods of zero flow.

Discharges at Storm Drain C and Xeriscape Garden were 

associated with rainfall at the Tunnel rain gage (appendix B). 

Periods of high-intensity rainfall coincided with peaks on the 

discharge hydrographs. Stormwater samples were collected 

from about 38 of these storms (appendix B). A total of 187 

water-quality samples were collected over the 6-year period. 

The exact number of storms is difficult to discern because 

some rainy periods produced multiple hydrograph peaks. 

Analysis of Water Quality Data

The results of the chemical analyses performed on H-3 

stormwater samples are summarized in appendix B. Additionally, for the stations with automatic samplers, the summary 

statistics are provided for each sample type, composite or grab 

(appendix C). These analytical results can be compared to 

results from rinsate blank samples (appendix A) to evaluate if 

contamination of the automatic sampling equipment may have 

affected the composite results. The detection of total zinc in 

the rinsate blank samples from Storm Drain C ranged from 2 

to 27 μg/L, and the concentration of total zinc in the composite samples ranged from 12 to 290 μg/L with a mean of 119 

μg/L. Of 24 sample analyses, only 3 Storm Drain C results 

were equal to or less than the highest reported concentration in 

blank samples. Therefore, contamination from the automaticsampling equipment was not an issue.
H-3 Stormwater Data Analysis 13

Constituent Concentrations during the Storm of 

April 20, 2002

For the storm of April 20, 2002, grab samples from 

the automated point sampler were analyzed for trace metals 

separately instead of being analyzed as a composite. Because 

of the flashy nature of streams in Hawaii, it is often difficult 

to manually obtain a sample during the early “first flush” of a 

storm. An automated point sampler, which is capable of collecting samples over the full extent of a storm, can eliminate 

this problem (fig. 3). Analysis of individual samples from an 

automated point sampler provided a profile of the constituent concentrations during the storm (fig. 4). These profiles 

can vary for individual constituents or groups of constituents. 

Concentrations of the trace metals cadmium, lead, zinc, and 

copper behaved in a similar manner with respect to the stream 

hydrograph during the course of the storm—initially high 

during the period of increasing discharge, decreasing over the 

next three samples to the peak flow, increasing slightly after 

the peak flow, and remaining nearly stationary through the 

final sample taken about one hour later. The profile for pH was 

relatively flat, fluctuating between 7.4 and 7.7 standard units 

with minor variations similar to the pattern of the metal concentrations. The profile for specific conductance did not have 

the variations that the metals and pH had. Instead, specific 

conductance gradually declined from the initial sample to the 

post-peak sample, and then remained relatively constant. 

The “first flush” phenomenon, higher concentrations at 

the beginning of runoff events, has been documented in studies elsewhere (Sartor and Boyd, 1972; Howell, 1978; Barrett 

and others, 1995a; Irish and others, 1995; Barber and others, 

2006) and in Hawaii (De Carlo and others, 2004; Beltran and 

De Carlo, 2005). This occurs as the particulate matter that has 

accumulated on the road surface is mobilized by storm runoff 

moving downgradient toward the roadway drainage. The 

Xeriscape (16226200)

Storm Drain C (212353157533001)

0.01 0.05 0.2 1 2 5 10 25 50 75 90 95 98 99 99.8 99.95 99.99

0.01

0.1

1

10

100

500

PERCENTAGE OF TIME INDICATED DISCHARGE WAS EQUALED OR EXCEEDED

DAILY MEAN DISCHARGE, IN CUBIC FEET PER SECOND

Figure 2. Flow-duration curves for Xeriscape Garden and Storm Drain C gaging stations, October 1998 to September 2004.
14 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

amount of particulate matter and the speed with which it will 

travel depend on the mass of the matter, the volume of runoff, 

and the roadway gradient. The “first flush” phenomenon 

necessitates that the rising limbs of storms be sampled in order 

to identify high-end concentrations and determine unbiased 

event-mean concentrations for the storms. 

Temporal and Spatial Distribution of Samples 

and Constituents During a Storm

As mentioned earlier, a complete set of samples for a 

storm consisted of five grab samples (one from each of the 

five stations), three flow-weighted time-composite samples, 

and one QA/QC sample. The collection of a complete set of 

samples begins when stormwater runoff reaches the predetermined stage thresholds of the automatic samplers. Because 

many storms happened late at night, the stations were often 

not accessed until the next morning. Thus, grab samples were 

frequently collected during the period of decreasing discharge 

of the storms, hours after the storms had peaked and the automatic samplers had completed their cycle. 

The temporal and spatial pattern of sampling for a complete set of samples is described using the storm of February 

14, 2003, as an example. The record at the Storm Drain C gage 

showed a relatively dry period of about two weeks following 

a January 1, 2003, storm that registered a maximum discharge 

of 27 cfs. Bidirectional traffic during this time averaged about 

42,000 vehicles per 24-hour period. The record also showed 

a very brief elevation in discharge (9.5 cfs) during the night 

of February 13, 2003, about 4 hours before the sampling had 

begun, but it was below the threshold set for sampling. The 

automatic sampler at Storm Drain C was triggered to collect 

samples at 2:53 AM on February 14, 2003, when the discharge 

was 14.11 cfs, and continued to collect samples until 5:28 AM 

(fig. 5). The automatic sampler at Xeriscape Garden started to 

collect samples at 12:55 AM, at a discharge of 174.8 cfs, and 

continued to collect samples until 5:04 AM. The automatic 

sampler at Quarantine Station was triggered to collect samples 

at 3:14 AM, at a discharge of 58.5 cfs, and continued to collect 

samples until 8:06 AM. The grab sample from Stadium was 

collected at 9:30 AM, more than an hour after the Quarantine 

Station automatic sampler had collected its last sample. The 

Bridge 8 grab sample was collected at 10:00 AM, approxi3:20

3:22

3:24

3:26

3:34

4:54

3:41

3:28

DISCHARGE

SAMPLE EVENT

0

5

10

15

20

25

30

2:30 PM 2:45 PM 3:00 PM 3:15 PM 3:30 PM 3:45 PM 4:00 PM 4:15 PM 4:30 PM 4:45 PM 5:00 PM

DISCHARGE, IN CUBIC FEET PER SECOND

TIME OF DAY

Figure 3. Discharge and sampling times for storm of April 20, 2002, at Storm Drain C.
H-3 Stormwater Data Analysis 15

TIME

2:30 PM 3:00 PM 3:30 PM 4:00 PM 4:30 PM 5:00 PM 2:30 PM 3:00 PM 3:30 PM 4:00 PM 4:30 PM 5:00 PM

TIME

0

40

80

120

160

0

5

10

15

20

25

30

SPECIFIC CONDUCTIVITY, IN MICROSIEMENS

PER CENTIMETER AT 25 DEGREES CELSIUS

DISCHARGE, IN CUBIC FEET PER SECOND

0

40

80

120

0

5

10

15

20

25

30

TOTAL ZINC, IN MICROGRAMS PER LITER

DISCHARGE, IN CUBIC FEET PER SECOND

0

10

20

30

40

0

5

10

15

20

25

30

TOTAL COPPER, IN MICROGRAMS PER LITER

DISCHARGE, IN CUBIC FEET PER SECOND

7.0

7.2

7.4

7.6

7.8

8.0

pH, IN STANDARD UNITS

0

2

4

6

8

10

TOTAL LEAD, IN MICROGRAMS PER LITER

0

0.1

0.2

0.3

0.4

0.5

TOTAL CADMIUM, IN MICROGRAMS PER LITER

Figure 4. Selected physical properties and constituents measured in water samples collected from Storm Drain C during the storm of 

April 20, 2002.

mately 7 hours after the sampler at Storm Drain C was first 

triggered. Grab samples from Storm Drain C, Xeriscape Garden, and Quarantine Station were all collected after 10:30 AM.

Mean discharge for the composite sample at Storm Drain 

C was 9.4 cfs, whereas mean discharge for the Xeriscape Garden composite sample was much greater, 265 cfs, and mean 

discharge for the Quarantine Station composite sample was 

only 49 cfs (table 4). The instantaneous discharge measured 

when the grab samples were collected varied among the sites 

but had dropped considerably from the peak or mean storm 

discharge. For Storm Drain C, this was a 94-percent decrease 

(9.4 to 0.56 cfs), and for Xeriscape Garden it was a 70-percent decrease (265 to 79 cfs). Discharge remained relatively 

constant between composite and grab samples at Quarantine 

Station. 
16 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

The concentration of TSS was relatively low in the Storm 

Drain C composite sample, 13 mg/L, much greater in the 

downstream composite sample collected at Xeriscape Garden, 

692 mg/L, and even greater in the composite sample collected 

farther downstream at Quarantine Station, 760 mg/L (table 

4). TSS concentration followed the same pattern as discharge, 

decreasing between the time of the composite sampling and 

the time of the grab sampling. At Xeriscape Garden, TSS concentration was 96 percent lower in the grab sample relative to 

the composite sample collected approximately 8 hours earlier. 

At the Quarantine Station, TSS concentration was 91 percent 

lower in the grab sample relative to the composite sample collected approximately 5 hours earlier. TSS concentrations were 

greater in the Bridge 8 grab sample than in the Storm Drain C 

grab sample collected within 40 minutes of each other late in 

the storm. 

Trace metal concentrations were all lower in the Storm 

Drain C composite sample than in the Xeriscape Garden composite sample, possibly because runoff on February 13, 2003, 

may have partly cleansed the highway of trace metals before 

that sample was collected (table 4). Trace metal concentrations 

in the Quarantine Station composite samples were all slightly 

lower than in the Xeriscape Garden composite sample but still 

higher than at Storm Drain C. Trace metal concentrations were 

considerably lower in the composite samples than in the grab 

samples at Xeriscape Garden and Quarantine Station and, to a 

lesser degree, in the Storm Drain C samples. Trace metal concentrations were relatively low in the grab samples collected 

at Stadium and Bridge 8. Of the trace metals, total copper 

concentrations exhibited the largest differences among composite samples. The concentration of total copper at Xeriscape 

Garden (67.8 μg/L) was approximately 7 times greater and 

that at Quarantine Station (58.4 μg/L) approximately 6 times 

greater than at Storm Drain C (9.5 μg/L). The total nitrogen 

and phosphorus constituents followed the same trends as the 

trace metals.

The constituent concentrations of the Storm Drain C 

composite sample represent the water quality of the H-3 

Highway runoff for the duration of the February 14, 2003, 

storm, and the constituent concentrations of the Bridge 8 grab 

sample represent the water quality of runoff from the undeveloped part of the North Halawa Stream drainage basin after 

the bulk of the storm had passed. Figure 13 illustrates that 

trace metal concentrations during a storm (at Storm Drain C 

in this example) can be higher during the early period of the 

hydrograph, before peak flow, and tend to decline as runoff 

decreases. Because of the time delay in sampling at Bridge 

8, constituent concentrations may be lower than if collected 

during the period of increasing discharge; therefore, the total 

input of the undeveloped part of the North Halawa Stream 

drainage basin may be underestimated. Supporting evidence 

for this was provided during the storms of February 26—27, 

2004, when Bridge 8 was sampled during a very high flow. 

The initial storm on the afternoon of February 26 triggered the 

Storm Drain C automatic sampler at 1:47 PM. By the time the 

sample at Bridge 8 was collected, 12:06 PM on February 27, a 

second rainstorm had increased flow in the stream. At the time 

of sampling at Bridge 8, the discharge had increased to 721 

cfs, the highest flow measured at Bridge 8 during this study. 

The trace metal concentrations in this sample were also the 

Bridge 8

grab

Stadium

grab

Xeriscape Garden Composite Start

Xeriscape Garden Composite

End

0

5

10

15

20

25

9:00 PM 11:00 PM 1:00 AM 3:00 AM 5:00 AM 7:00 AM 9:00 AM 11:00 AM 1:00 PM 3:00 PM

POINT ON HYDROGRAPH

AT WHICH BOTTLES

FILLED FOR 

COMPOSITE

SAMPLE AT 

STORM DRAIN C

DISCHARGE AT

STORM DRAIN C

DISCHARGE, IN CUBIC FEET PER SECOND

TIME OF DAY

Xeriscape Garden

grab

Storm Drain C

grab

Quarantine Station

grab

Quarantine

Station

Composite Start

Quarantine

Station

Composite

End

Figure 5. Sampling times at all stations for storm of February 14, 2003, based on discharge at 

Storm Drain C. The start time and end time for the composite sampling at Xeriscape Garden and 

Quarantine Station are denoted by dashed lines.
Table 4. Constituent concentrations and loads at all stations during the storm of February 14, 2003.[<, less than; –, no data; E, estimated; cfs, cubic feet per second; mS/cm at 25°C, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter; N, nitrogen; mg/

pounds per day]

Sampling sites and times on February 14, 2003

Storm Drain C 

Composite

Xeriscape

Garden

Composite

Quarantine

Station

Composite

Stadium

Grab

Bridge 8

Grab

Quarantine

Station Grab

S

Property or constituent Units 3:11 AM 3:58 AM 5:40 AM 9:30 AM 10:00 AM 10:35 AM 

Temperature, water degrees Celsius 17.2 20.3 19.7 19.5 17.9 18.3 Discharge cfs 9.4 265 49 – – – Discharge, instantaneous cfs – – – 235 47 51 Gage height feet – – – 1.5 96.79 5.13 Specific conductance, field mS/cm at 25°C – 43 – 74 76 78 

Specific conductance, lab mS/cm at 25°C 36 50 55 78 78 84 Chemical oxygen demand mg/L <10 160 40 10 <10 10 

load lb/day <507 228,706 10,572 12,676 <2,535 2,751 

pH, field standard units – 6.3 – 7.2 5.8 7.5 

pH, lab standard units 7.6 6.9 7.3 7.6 7.3 7.5 

Total suspended solids mg/L 13 692 760 91 46 65 

load lb/day 659 989,152 200,873 115,351 11,662 17,881 

Oil and grease mg/L – – – <7 <7 <7 

load lb/day – – – <8873 <1775 <1926 

Total nitrogen mg/L 0.28 3.5 3.4 0.77 0.44 0.56 

load lb/day 14 5,003 899 976 112 154 

Nitrogen ammonia dissolved mg/L as N E0.03 E0.03 <0.04 <0.04 <0.04 <0.04 

load lb/day E1.5 E43 <11 <51 <10 <11 

Nitrogen, nitrite, dissolved mg/L as N <0.008 <0.008 E0.004 E0.005 <0.008 E0.007 

load lb/day <0.4 <11 E1 E6 <2 E2 

Nitrogen, ammonia + organic, total mg/L as N 0.25 3.4 3.3 0.59 0.33 0.43 

load lb/day 13 4,860 872 748 84 118 

Nitrogen, nitrite + nitrate, dissolved mg/L as N <0.06 0.09 0.1 0.18 0.12 0.13 

load lb/day <3 129 26 228 30 36 

Total phosphorus mg/L E0.04 1.12 1.07 0.19 0.1 0.13 

load lb/day E2 1,601 283 241 25 36 

Phosphorus dissolved mg/L <0.04 E0.03 <0.04 0.04 <0.04 <0.04 

load lb/day <2 E43 <11 51 <10 <11 

Total cadmium mg/L 0.06 0.25 0.17 <0.04 <0.04 0.04 

load lb/day 0.003 0.4 0.05 <0.05 <0.01 0.01 

Total copper mg/L 9.5 67.8 58.4 13.1 5.3 7.6 

load lb/day 0.482 96.91 15.44 16.61 1.34 2.09 

Total lead mg/L 2.47 6.03 5.59 2.85 0.25 0.68 

load lb/day 0.125 8.6 1.5 3.6 0.063 0.187 

Total zinc mg/L 38 91 85 28 7 14 

load lb/day 1.93 130.08 22.47 35.49 1.77 3.85 

Total petroleum hydrocarbons mg/L – – – 3 <2 <2 

load lb/day – – – 3803 <507 <550 

Total dissolved solids mg/L 16 32 37 54 47 53 

load lb/day 811 45,741 9,779 68,450 11,915 14,580 
18 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

highest measured at Bridge 8 during this study and are denoted 

as the Bridge 8 maximum observations in appendix C, table 

C1, for copper (99.4 μg/L), lead (7.95 μg/L), zinc (129 μg/L), 

and cadmium (0.4 μg/L). 

Spearman-Rank correlation analysis (SAS Institute, 

1990) was conducted to examine the relationship between 

discharge and constituent concentration at Bridge 8. This 

nonparametric procedure provides a measure of the intensity 

of association between two variables. The correlation coefficient, rho (ρ), is computed using ranks of the data rather 

than actual data values (Helsel and Hirsh, 1992). Correlation 

coefficient values range between -1 and +1, with a negative 

value indicating an inverse relationship between the data ranks 

and zero representing no relationship. The probability that the 

null hypothesis, defined as no correlation existing between the 

variables, is true is expressed as the p-value (p). A p-value of 

0.05 was used as the cutoff in the analyses to identify significant correlations. Correlations with p-values at or below the 

0.05 significance level presume a 95-percent or greater confidence that the correlations are scientifically valid. The analysis 

using Spearman-Rank correlation (n = 11) determined that the 

instantaneous discharge measurements at Bridge 8 were positively correlated with concentrations of the trace metals copper 

(ρ = 0.81, p = 0.0026), lead (ρ = 0.76, p = 0.0062,), zinc (ρ = 

0.78, p = 0.0042), and cadmium (ρ = 0.85, p = 0.0008). This 

suggests that the undeveloped basin upstream of Bridge 8 may 

be contributing trace metals into North Halawa Stream.

Site Comparison of Water-Quality Data

The results of chemical analyses indicate some important 

spatial trends (figs. 6, 7). The boxplots in figures 6 and 7 were 

computed without estimates for censored data. For that reason, 

boxplots of data that included censored results are displayed 

using the “boxplot at sunrise” method from Helsel (2005) 

without estimated arithmetic means and distributions below 

the highest minimum reporting level (MRL; if more than 

one; see table 3). This graphic method provides an accurate 

portrayal of the dataset. The unseen proportion of the boxplot 

below the MRL illustrates the amount of censored data in 

the dataset. In general, for both composite samples and grab 

samples, nutrient, TDS, and TSS concentrations were lower at 

Storm Drain C than at both the upstream station, Bridge 8, and 

the downstream stations. In most cases, the concentrations in 

the actual stream decreased in a downstream order because of 

the larger volume of water downstream causing greater dilution of the constituents. This trend is reversed for most trace 

metals, which tended to have higher concentrations at Storm 

Drain C than at the upstream and downstream stations. These 

trends suggest different source areas for the different constituents. Higher amounts of trace metals are deposited onto 

the roadway surface by vehicular traffic, whereas the forested 

basin contributes greater amounts of nutrients and eroded sediments into the stream. 

Overall, the composite samples tended to have higher 

constituent concentrations than the grab samples, probably 

because grab samples were generally collected after the first 

flush of the storm. However, specific conductance and the 

concentrations of TDS were notably lower in the composite 

samples. Total cadmium concentrations were higher in the 

composite samples, but show little difference among the sites, 

whereas in the grab samples, Storm Drain C appears to have 

higher concentrations of cadmium than the other stations. 

The differences between the sampling methods may account 

for the differences in the constituent concentrations. The 

composite samples cover a much broader period of the storm 

runoff, including the earlier “first flush” and peak flows that 

can mobilize the greater part of the road-deposited material, 

whereas most grab samples were collected after a majority of 

the runoff had passed.

The contributing drainage area and resultant storm runoff 

volume are much smaller at Storm Drain C (table 1) than at 

stations along Halawa Stream. The influence of discharge 

is made more evident when comparing daily loads (fig. 8A). 

The boxplots in figure 8 were computed using Robust ROS 

estimates for censored data. Daily loads were calculated using 

equation 1, taking into account discharge—instantaneous 

for discrete samples and event mean for composite samples. 

Because of the comparatively small discharge, the absolute 

contribution from Storm Drain C, in terms of constituent 

loads, was much smaller than at the stations downstream. 

Storm Drain C has a much smaller drainage area, and therefore the pattern is different when comparing daily yields 

(calculated using equation 2). The relative contribution of 

Storm Drain C is in general much greater than from the stations downstream. Notably,however, concentrations and loads 

of TDS and TSS were consistently lower at Storm Drain C. 

This is because of the low amounts of sediments deposited on 

the highway as compared to the amounts of sediments being 

eroded from nonpaved areas and carried into the stream during 

rainstorms.

Comparison of Wet and Dry Seasons 

In general, there were only minor differences in the 

ranges and distributions of constituent concentrations between 

the wet and dry seasons. The HDOH defines the wet season as 

November 1 to April 30 and the dry season as May 1 to October 31 (State of Hawaii Department of Health, 2000). There 

were no obvious differences between seasons for composite 

samples or grab samples at Storm Drain C for any of the constituents. The buildup of material on the roadway during the 

longer dry periods of the dry season is most likely offset by 

more frequent street sweeping. There were, however, noticeable differences between seasons at some sites for nitrite plus 

nitrate (fig. 9) and total copper (fig. 10). Concentrations of 

nitrite plus nitrate were higher during the wet season at Bridge 

8, Xeriscape Garden, and Stadium. Concentrations of total Cu 

were higher during the wet season in the composite samples 

from Xeriscape Garden and Quarantine Station.
Figure 6. Boxplots of select constituent concentrations from grab samples collected over the entire period of the stud

0

0.20.40.60.81.0 (11) (20) (22) (11) (10)

NITROGEN, NITRITE + NITRATE, DISSOLVED,

IN MILLIGRAMS PER LITER

0.06

02468 (11) (20) (22) (11) (10)

NITROGEN, AMMONIA + ORGANIC, TOTAL,

IN MILLIGRAMS PER LITER

0.1

SAMPLING STATION

Stadium

Quarantine

Xeriscape

Storm Drain C

Bridge 8

Observations below lower fenceObservations above upper fence

Maximum observation (below upper fence)

25th percentile

Mean (Only with no censored values)

Median

Minimum observation

Lower fence (above lower fence)

(1.5xIQR)

Upper fence

(1.5xIQR)

75th percentile

MinimumReporting Level (MRL)

10

(10) Number of observations

EXPLANATION

Interquartile

Range

(IQR)
0

1,0002,0003,0004,0005,0006,000 (11) (38) 

Xerisca

Storm Drain C

Bridge 8

SAMPLIN

 TOTAL SUSPENDED SOLIDS,

IN MILLIGRAMS PER LITER

0

50

100150200 (11) (16) 

TOTAL DISSOLVED SOLIDS,

IN MILLIGRAMS PER LITER

02468 (11) (20) (21) (11) (10)

Stadium

Quarantine

Xeriscape

Storm Drain C

Bridge 8

SAMPLING STATION

TOTAL NITROGEN,

IN MILLIGRAMS PER LITER

0

100200300400 (9) (18) (19) (11) (9)

SPECIFIC CONDUCTANCE, IN MICROSEIMENS

PER CENTIMETER AT 25 DEGREES CELSIUS

0

0.51.01.52.02.5 (11) (20) (22) (11) (10)

SAMPLING STATION

Stadium

Quarantine

Xeriscape

Storm Drain C

Bridge 8

0.06

TOTAL PHOSPHORUS,

IN MILLIGRAMS PER LITER

0

50

100150200 (11) (18) (21) (11) (10)

10

CHEMICAL OXYGEN DEMAND,

IN MILLIGRAMS PER LITER

Figure 6. Boxplots of select constituent concentrations from grab samples collected over the entire period of the study—Continued.
Figure 6. Boxplots of select constituent concentrations from grab samples collected over the entire period of the study—Continued. 6.5 7.0

7.58.08.5 (11) (29) (

pH, LAB, IN STANDARD UNITS

Xeriscap

Storm Drain C

Bridge 8

SAMPLING 

56789

10 (9) (19) (

pH, FIELD, IN STANDARD UNITS

0

50

100

150

200

250

300

TOTAL ZINC, IN MICROGRAMS PER LITER

SAMPLING STATION

Stadium

Quarantine

Xeriscape

Storm Drain C

Bridge 8

(11) (28) (21) (14) (9)

1

0

25

50

75

100

125

TOTAL COPPER, IN MICROGRAMS PER LITER

(11) (28) (21) (14) (9)

1

0

0.20.40.60.8

TOTAL CADMIUM, IN MICROGRAMS PER LITER 0.04

SAMPLING STATION

Stadium

Quarantine

Xeriscape

Storm Drain C

Bridge 8

(11) (23) (15) (14) (9)

05

1015202530

1

TOTAL LEAD, IN MICROGRAMS PER LITER

(11) (28) (21) (14) (9)
6.5 7.0 7.5 8.0 8.5 (24) (25) (9)

pH, LAB, IN STANDARD UNITS

5.56.06.57.07.58.0 (7) (6) (3)

pH, FIELD, IN STANDARD UNITS

0

100200300

 TOTAL ZINC, IN MICROGRAMS PER LITER

1

(24) (25) (9)

0

255075

100125150

TOTAL COPPER , IN MICROGRAMS PER LITER

1

(24) (25) (9)

0

0.10.20.30.40.50.6

TOTAL CADMIUM, IN MICROGRAMS PER LITER 0.04

(16) (16) (9)

SAMPLING STATION

Quarantine

Xeriscape

Storm Drain C

0

1020304050

1

TOTAL LEAD, IN MICROGRAMS PER LITER 

(24) (25) (9)

SAMPLING STATION

Quarantine

Xeriscape

Storm Drain C

SAMPLING STATION

Quarantine

Xeriscape

Storm Drain C

Lower fence 

(1.5xIQR)

Upper fence

(1.5xIQR)

10

(10) 

EXPLA

Interquartile

Range

(IQR)

Figure 7. Boxplots of select constituent concentrations from composite samples collected over the entire period of the study. Shaded bars in 

zinc boxplot represent quality control rinsate blank concentration ranges.
0

0.050.100.150.200.250.30 

NITROGEN, NITRITE + NITRATE, DISSOLVED,

IN MILLIGRAMS PER LITER

Storm Dr

0

2.55.0

7.5

10.012.515.0 

NITROGEN, AMMONIA + ORGANIC, TOTAL,

IN MILLIGRAMS PER LITER

0

500

1,0001,5002,0002,500 (28) (34) (8)

TOTAL SUSPENDED SOLIDS,

IN MILLIGRAMS PER LITER

10

0

20406080

100

TOTAL DISSOLVED SOLIDS,

IN MILLIGRAMS PER LITER

(17) (15) (8)

0

2.55.07.5

10.012.515.0 (19) (16) (7)

TOTAL NITROGEN,

IN MILLIGRAMS PER LITER

255075

100125150 (8) (5) (2)

SPECIFIC CONDUCTANCE, IN MICROSEIMENS

PER CENTIMETER AT 25 DEGREES CELSIUS

01234 (20 (16) (7)

TOTAL PHOSPHORUS,

IN MILLIGRAMS PER LITER

0.06

0

100200300400500

CHEMICAL OXYGEN DEMAND,

IN MILLIGRAMS PER LITER

(20) (17) (6)

10

SAMPLING STATION

Quarantine

Xeriscape

Storm Drain C

SAMPLING STATION

Quarantine

Xeriscape

Storm Drain C

SAMPLING STATION

Quarantine

Xeriscape

Storm Drain C

Figure 7. Boxplots of select constituent concentrations from composite samples collected over the entire period of the study. Shaded 

zinc boxplot represent quality control rinsate blank concentration ranges—Continued.
Figure 8. Boxplots of daily loads (

A) and yields (

B) for select constituents from composite samples only, collected over the entire period of the study

0

1.25

2.5

3.75

5

6.25

NITROGEN, AMMONIA + ORGANIC, TOTAL

IN TONS PER DAY PER SQUARE MILE

(20) (16) (7)

0

5

10152025

NITROGEN, AMMONIA + ORGANIC, TOTAL

IN TONS PER DAY

(20) (16) (7)

0

50

100150

NITROGEN, NITRITE + NITRATE, DISSOLVED,

IN POUNDS PER DAY PER SQUARE MILE

(19) (16) (7)

0

200400600

NITROGEN, NITRITE + NITRATE, DISSOLVED,

IN POUNDS PER DAY

(19) (16) (7)

0

1.25

2.5

3.75

5

6.25

TOTAL NITROGEN, IN TONS PER DAY PER SQUARE MILE

(19) (16) (7)

0

5

10152025

TOTAL NITROGEN, IN TONS PER DAY

(19) (16) (7)

SAMPLING STATION

Quarantine

Xeriscape

Storm Drain C

SAMPLING STATION

Quarantine

Xeriscape

Storm Drain C

SAMPLING STATION

Quarantine

Xeriscape

Storm Drain C

AB

Lower fence 

(1.5xIQR)

Upper fence

(1.5xIQR)

10

(10) 

EXPLA

Interquartile

Range

(IQR)
010

203040

TOTAL DISSOLVED SOLIDS,

IN TONS PER DAY PER SQUARE MILE

0

25

5075

100

TOTAL DISSOLVED SOLIDS,

IN TONS PER DAY

(17) (15) (8)

(17) (15) (8)

0

250

500750

1,0001,250

TOTAL SUSPENDED SOLIDS,

IN TONS PER DAY PER SQUARE MILE

(28) (34) (8)

0

1,0002,0003,0004,000

5,000

TOTAL SUSPENDED SOLIDS,

IN TONS PER DAY

(28) (34) (8)

0

0.5

1

1.5

2

TOTAL PHOSPHORUS, 

IN TONS PER DAY PER SQUARE MILE

(20) (16) (7)

0

1.252.503.75

5.006.25

TOTAL PHOSPHORUS,

IN TONS PER DAY

(20) (16) (7)

SAMPLING STATION

Quarantine Xeriscape Storm Drain C

SAMPLING STATION

Quarantine Xeriscape Storm Drain C

SAMPLING STATION

Quarantine Xeriscape Storm Drain C

AB

Figure 8. Boxplots of daily loads (A) and yields (B) for select constituents from composite samples only, collected over the 

entire period of the study.—Continued.
Figure 8. Boxplots of daily loads (

A) and yields (

B) for select constituents from composite samples only, collected over the entire period of the 

0

0.20.40.60.8

TOTAL CADMIUM, IN POUNDS PER DAY PER SQUARE MILE

0

0.51.01.52.0

TOTAL CADMIUM, IN POUNDS PER DAY

0

50

100150200250

TOTAL COPPER, IN POUNDS PER DAY PER SQUARE MILE

(24) (25) (9)

0

100200300400500

TOTAL COPPER, IN POUNDS PER DAY

(24) (25) (9)

0

5

1015202530

TOTAL LEAD, IN POUNDS PER DAY PER SQUARE MILE

(24) (25) (9)

0

102030405060

TOTAL LEAD, IN POUNDS PER DAY

(24) (25) (9)

0

100200300400

TOTAL ZINC, IN POUNDS PER DAY PER SQUARE MILE

(24) (25) (9)

0

200400600800

TOTAL ZINC, IN POUNDS PER DAY

(24) (25) (9)

Storm Dra

SAMPLING STATION

Quarantine

Xeriscape

Storm Drain C

SAMPLING STATION

Quarantine

Xeriscape

Storm Drain C

SAMPLING STATION

Quarantine

Xeriscape

Storm Drain C

AB
Wet Season

Composite

Dry Season

Composite

Dry Seaso

Grab

Wet Season

Composite

Dry Season

Composite

Dry Season

Grab

Wet Season

Grab

Wet Season

Dry Season

Grab

Wet Season

Grab

Composite

Dry Season

Composite

0.06

(2) (5) (6) (5)

Quarantine Station

NITROGEN, NITRITE + NITRATE, DISSOLVED,

IN MILLIGRAMS PER LITER

0

0.20.40.60.81.0

0

0.20.40.60.81.0 (5) (5)

0.06

Stadium

NITROGEN, NITRITE + NITRATE, DISSOLVED,

IN MILLIGRAMS PER LITER

(4) (12) 

Xeriscape Garden

NITROGEN, NITRITE + NITRATE, DISSOLVED,

IN MILLIGRAMS PER LITER

0

0.20.40.60.81.0

0.06

(8) (11) (7) (13)

Storm Drain C

NITROGEN, NITRITE + NITRATE, DISSOLVED,

IN MILLIGRAMS PER LITER

0

0.20.40.60.81.0

0.06

(6) (5)

NITROGEN, NITRITE + NITRATE, DISSOLVED,

IN MILLIGRAMS PER LITER

Bridge 8

0

0.20.40.60.81.0

Observations bObservations a

Maximum obse(below upper fe

25th percentile

Mean (Only wit

Median

Minimum obse

Lower fence (above lower f

(1.5xIQR)

Upper fence

(1.5xIQR)

75th percentile

MinimumReporting Leve

10

(10) Number of obs

EXPLANATION

Interquartile

Range

(IQR)

Figure 9. Boxplots of nitrite plus nitrate concentrations, collected over the entire period of the study, compiled by wet and dry s
Wet Season

Composite

Dry Season

Composite

Dry Season

Grab

Wet Season

Composite

Dry Season

Composite

Dry Season

Grab

Wet Season

Grab

Wet Season

Dry Season

Grab

Wet Season

Grab

Composite

Dry Season

Composite

1

Stadium

TOTAL COPPER, IN MICROGRAMS PER LITER

0

255075

100125150

1

Quarantine Station

TOTAL COPPER, IN MICROGRAMS PER LITER

0

255075

100125150

0

255075

100125150

Xeriscape Garden

TOTAL COPPER, IN MICROGRAMS PER LITER

0

255075

100125150

1

TOTAL COPPER, IN MICROGRAMS PER LITERStorm Drain C

1

TOTAL COPPER, IN MICROGRAMS PER LITERBridge 8

0

255075

100125150

(2) (7) (6) (8) (5) (4)

(6) (5) (10) (14) (7) (21) (9) (19) (9

Observations belObservations abo

Maximum observ(below upper fen

25th percentile

Mean (Only with 

Median

Minimum observ

Lower fence (above lower fe

(1.5xIQR)

Upper fence

(1.5xIQR)

75th percentile

MinimumReporting Level (

10

(10) Number of obser

EXPLANATION

Interquartile

Range

(IQR)

Figure 10. Boxplots of total copper concentrations, collected over the entire period of the study, compiled by wet and dry season
H-3 Stormwater Data Analysis 29

Comparison with State of Hawaii Department of 

Health Criteria

To determine whether the State of Hawaii water-quality 

standards (table 5) were exceeded during storms, sample data 

were compared to the criteria applicable to streams (appendix 

D) (State of Hawaii Department of Health, 2000). The HDOH 

water-quality standards were not designed for stormwater 

sampling. Because the samples in this study were collected 

exclusively during storms, they are not representative of nonstorm conditions, and therefore constituent concentrations are 

biased. These comparisons are simply meant to provide a point 

of reference for the stormwater sample results.

The HDOH water-column criteria for streams utilize the 

geometric means for selected constituents. The geometric 

mean is an estimate of the median when the logarithms of the 

data are symmetric and is used to reduce the effects of outliers 

on the mean value of a dataset. The HDOH water-column criteria for streams also include concentration values that should 

not be exceeded more than 10 and 2 percent of the time (table 

5). These can be compared to the 90th and 98th percentiles of 

the measured data. Values for the 90th and 98th percentiles were 

computed by ranking the data from lowest to highest in value 

and then dividing the rank by the total number of samples 

(Iman and Conover, 1983). Percentiles were interpolated when 

necessary. Percentiles were only computed when the number 

of samples was greater than or equal to five.

Geometric means were calculated using all samples 

collected during the study period for each season—wet and 

dry; for each sampling method—grab and composite; and 

for each water-quality sampling site (appendix D). Censored 

values were estimated using the robust ROS method before 

calculating the geometric and arithmetic means. The HDOH 

water-quality geometric mean standards were exceeded in the 

majority of the comparisons, as were the 10- and 2-percentof-the-time exceedence values (appendix D). The State of 

Hawaii water-quality standards for physical properties—pH, 

temperature, dissolved oxygen, and specific conductance—

are given as numeric values or ranges not to be exceeded, and 

they consider ambient conditions in the evaluation (table 5). 

None of the composite samples had physical properties that 

exceeded the HDOH water-quality standards. There were 

some exceedances in the grab samples. Two exceedances 

for pH were in samples collected at Quarantine Station and 

Stadium during the same storm. One storm sample from Xeriscape Garden had a low value for dissolved oxygen and a high 

value for specific conductance. This was the only exceedance 

for dissolved oxygen. Storm Drain C samples only exceeded 

the criteria for specific conductance on one occasion.

Because most runoff events are relatively short in duration and streamflow in Halawa Stream is intermittent, it 

may be more appropriate to use criteria based on the effects 

of acute exposure on aquatic biota rather than long-term or 

chronic toxicity effects (Driscoll and others, 1990a). For many 

priority and nonpriority pollutants, the EPA has established 

a Criteria Maximum Concentration (CMC), which is the 

maximum constituent concentration to which aquatic biota can 

be acceptably exposed for brief periods (U.S. Environmental 

Protection Agency, 2006). The State of Hawaii toxic pollutant 

standards for the dissolved fraction of trace metals and organic 

chemical compounds that are applicable to all surface waters, 

fresh and salt, in the State also consider both acute and chronic 

conditions (State of Hawaii Department of Health, 2000). 

Since 2000, the H-3 water-quality samples have only been 

analyzed for total trace metal concentrations and not for the 

dissolved fraction, and therefore most of the trace metal data 

cannot be compared to the HDOH or USEPA water-quality 

criteria (U.S. Environmental Protection Agency, 2006).

There were only two exceedances of the HDOH freshwater toxic pollutants standards, both at Storm Drain C. One 

result for dissolved copper, collected from a grab sample on 

January 26, 2000, was 8.6 μg/L, higher than the 6.0 μg/L acute 

and chronic HDOH standard but less than the USEPA CMC of 

13 μg/L. For dissolved zinc, a December 1, 1999, grab sample 

yielded 39 μg/L, higher than the 22 μg/L acute and chronic 

HDOH standards but well under the USEPA CMC of 120 

μg/L. There was one toxic pollutant, hexachlorocyclopentadiene, for which the MRL of 5 μg/L was higher than the HDOH 

standard of 2 μg/L. Consequently, sample concentrations 

determined as less than the MRL could still be greater than the 

HDOH standard. For this reason, exceedances could not be 

determined.

Comparison with Data Collected Before and 

During Highway Construction

Water-quality data from before, during, and after H-3 

Highway construction were compared at Xeriscape Garden 

and Stadium stations (fig. 11). Elevated levels of TDS and 

specific conductance were observed during the construction 

period, especially at Stadium, with postconstruction levels 

returning to the preconstruction levels. Small differences in 

lead and zinc levels were measured among all periods and 

sites. Concentrations of copper, total phosphorus, and nitrogen 

(ammonia plus organic and nitrite plus nitrate) were higher 

after construction, especially at Xeriscape Garden. Similarly, 

TSS concentrations were much higher after construction at 

both sites, suggesting that TSS is associated with highway 

usage.

Comparisons with Other Studies in Hawaii

Fujiwara (1973) investigated urban stormwater pollution 

at four drainage sites on Oahu that included varying extents 

of residential, commercial, and industrial land use. A comparison of the compiled data from urban drainages with those 

of Storm Drain C showed that trace metal, nutrient, and COD 

concentrations were greater in the urban drainages (fig. 12). 

Additionally, comparisons with results from the Yamane and 

Lum (1985) urban runoff study in Mililani also showed greater 

concentrations in the urban stormwater. 
30 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

Mililani Drain B had a smaller drainage area than Mililani Drain A, with fewer residences and no commercial land 

use. Mililani Drain-A constituent concentrations were consistently somewhat higher than in the Drain-B samples. Lead and 

zinc concentrations were highest in the 1973 study, as compared to both the 1985 study and the current study, perhaps as 

a result of the past use of leaded gasoline, not entirely eliminated in Hawaii until 1989 (Sutherland and Tolosa, 2000; De 

Carlo and Spencer, 1997). COD and nutrient concentrations in 

samples from Mililani Drain B and Storm Drain C were similar, whereas the more intensively used areas in the 1973 study 

and Mililani Drain A had higher concentrations. The bulk of 

the TSS data were similar among the studies, with some high 

outlier concentrations measured at Mililani Drain A.

Constituent Concentrations and Storm 

Characteristics

The relationships among the constituent concentrations 

measured in storm runoff at Storm Drain C and the characteristics of the sampled storms were investigated. Storm 

characteristics were calculated from data relevant to the 

sampled storms, the periods of sample collection, vehicular 

traffic before and during the sample collection, the preceding 

dry periods, and characteristics of the preceding storms (fig. 

13). The duration of a storm (DUR) was defined as the time 

between the start of flow greater than 0.10 cfs until the final 

recession of flow when flow returned below 0.10 cfs at Storm 

Drain C. The sampling duration (SDUR) was defined as the 

time between the start of flow greater than 0.10 cfs until the 

grab sample or final composite sample was collected at Storm 

Drain C. The sampling-period variables were included because 

events that take place after the last sample is collected do 

not affect the sample. The antecedent dry period (DRY) was 

defined as the period before the storm, from the last runoff 

event greater than 0.10 cfs. The preceding storm periods 

(PDUR) were bounded by the start of flow greater than 0.10 

cfs and the start of the dry period.

Confounding Variables

The calculated storm characteristics are not the only factors affecting the constituent concentrations; other factors can 

affect those concentrations. Data on the timing, frequency, and 

effectiveness of street sweeping were not available for analysis 

in this report. Assuming that street sweeping was conducted 

during dry periods, the net accumulation of material on the 

highway before the sampled storms would not be strictly 

related to length of the dry period or the amount of traffic during that period. The amount of material that accumulates on 

the highway before the sampled storms is also affected by the 

numerous small runoff events that occur during the antecedent 

period. These events do not trigger the automatic samplers or 

provide enough runoff for manual grab samples. The amount 

of material removed by each of these events was not meaTable 5. State of Hawaii water-quality standards specific for streams.

[mg/L, milligrams per liter; NTU, Nephelometric Turbidity Unit; N, nitrogen; Wet season, November 1 to April 30; Dry season, May 1 to October 31; 

ambient conditions are conditions that would occur in the receiving waters if these waters were not influenced by the proposed new human activity; source: State 

of Hawaii Department of Health, 2000]

Property or constituent Season Geometric mean not to exceed 

the given value

Not to exceed the given value 

more than 10 percent of the time

Not to exceed the given value 

more than 2 percent of the time

Total nitrogen (mg/L as N) Wet 0.25 0.52 0.8

Dry 0.18 0.38 0.6

Nitrogen, nitrite + nitrate Wet 0.07 0.18 0.3

 (mg/L as N) Dry 0.03 0.09 0.17

Total phosphorus (mg/L as P) Wet 0.05 0.1 0.15

Dry 0.03 0.06 0.08

Total suspended solids (mg/L) Wet 20 50 80

Dry 10 30 55

Turbidity (NTU) Wet 5 15 25

Dry 2 5.5 10

pH Shall not deviate more than 0.5 units from ambient conditions and shall not be lower than 5.5 nor 

higher than 8.0

Oxygen, dissolved Not less than 80 percent saturation, determined as a function of ambient water temperature and 

barometric pressure

Temperature Shall not vary more than 1 degree Celsius from ambient conditions

Specific conductance Not more than 300 micromhos (microsiemens) per centimeter
SAMPLING STATION SAMPLING STATION

0

20406080

TOTAL LEAD, IN MICROGRAMS PER LITER

0

50

100150200250300

TOTAL ZINC, IN MICROGRAMS PER LITER

10

0

500

1,0001,500

SPECIFIC CONDUCTANCE, IN MICROSEIMENS

 PER CENTIMETER AT 25 DEGREES CELSIUS

0

1,0002,0003,0004,0005,0006,000

TOTAL SUSPENDED SOLIDS,

IN MILIGRAMS PER LITER

10

0

200400600800

TOTAL DISSOLVED SOLIDS,

IN MILIGRAMS PER LITER

(10) (37) (34) (66) (10) (5) (19) (16) (46) (9)(5) (19) (16) (32) (9) (23) (94) (91) (24) (9) (3) (19) (1

Stadium

Xeriscape

Stadium

Xeriscape

Preconstruction

During construction

Postconstruction

Xeriscape

Stadium

Xeriscape

SAMPLING 

Xeriscape

Stadium

Xeriscape

Xeriscape

Stadium

Xeriscape

ObservObserv

Maximu(below 

25th pe

Mean (

Median

Minimu

Lower fence (above 

(1.5xIQR)

Upper fence

(1.5xIQR)

75th pe

MinimuReporti

10

(10) Numbe

EXPLANATIO

Interquartile

Range

(IQR)

Figure 11. Boxplots comparing select constituent concentrations from Xeriscape Garden and Stadium, collected over the entire period of the from those sites collected before and during construction of the H-3 Highway.
SAMPLING STATION

0

0.20.40.60.81.0

0.06

NITROGEN, NITRITE + NITRATE, DISSOLVED,

IN MILLIGRAMS PER LITER

01234

0.06

TOTAL PHOSPHORUS,

IN MILIGRAMS PER LITER

(14) (13) (38) (10)

(8) (38) (35) (38) (10)

Stadium Xeriscape Xeriscape Stadium Xeriscape

SAMPLING STATION

Stadium Xeriscape Xeriscape Stadium Xeriscape

0

2550

75

100125150

TOTAL COPPER, IN MICROGRAMS PER LITER

(1) (19) (16) (46) (9)

0

2.55.07.5

10.012.515.0

NITROGEN, AMMONIA + ORGANIC, TOTAL,

IN MILLIGRAMS PER LITER

0.2

(8) (38) (35) (38) (10)

Preconstruction

During construction

Postconstruction

 Boxplots comparing select constituent concentrations from Xeriscape Garden and Stadium, Figure 11.collected over the entire period of the study, with data from those sites collected before and duringconstruction of the H-3 Highway—Continued.
02468

0.1

NITROGEN, AMMONIA + ORGANIC, TOTAL,

IN MILLIGRAMS PER LITER

0

100020003000

TOTAL SUSPENDED SOLIDS,

IN MILLIGRAMS PER LITER

10

0

500

100015002000

TOTAL LEAD, IN MICROGRAMS PER LITER 100

0

250500750

10001250

TOTAL ZINC, IN MICROGRAMS PER LITER

1

0

0.51.01.52.02.53.0

TOTAL PHOSPHORUS,

IN MILLIGRAMS PER LITER

0.06

0

100200300400500

10

CHEMICAL OXYGEN DEMAND,

IN MILLIGRAMS PER LITER

SAMPLING STATION

Mililani Drain B

Urban Oahu

Drainages

Mililani Drain A

Storm Drain C

a b b

SAMPLING STATION

Mililani Drain A

Mililani Drain B

Storm Drain C

Urban Oahu

Drainages

a b b

SAMPLING STATION

Mililani Drain A

Mililani Drain B

Storm Drain C

Urban Oahu

Drainages a b b

Storm Drain C

Storm Drain C

Storm Drain C

Lower fence 

(1.5xIQR)

Upper fence

(1.5xIQR)

10

(10) 

EX

Interquartile

Range

(IQR)

Figure 12. Boxplots comparing select constituent concentrations from Storm Drain C, collected over the entire period of the study, with data from: a

Yamane and Lum (1985).
34 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

sured. Because these smaller events may or may not move 

large amounts of material, the length of antecedent dry period 

was defined as the period since the last rainfall greater than 

or equal to 0.10 inch. Another confounding characteristic of 

some storms is that the rate of runoff can rise and fall numerous times at the start of a storm at rates that do not trigger the 

automatic samplers. Not only do these low-intensity runoff 

events remove an unknown amount of material before the start 

of sampling, they also cannot be considered part of the antecedent dry period because they are part of the sampled storm.

Storm Characteristics

Storm characteristics are the variables unique to each 

storm that affect the buildup and washoff of the constituents 

on the highway. Storm characteristics used in this study were 

either previously determined in other studies to be significant 

factors affecting water quality or included because scientific 

theory suggested their significance (Irish and others, 1995 and 

1998). These variables and how they were computed are listed 

in table 6. The storm characteristics were calculated from time 

intervals determined by discharge measured at Storm Drain C 

and rainfall measured at the Tunnel rain gage. These characteristics are summarized in table 7. Because the characteristics 

of each storm are calculated from the same forces driving the 

events, there is a lack of independence and therefore a high 

likelihood of correlations among characteristics within each 

storm. Spearman rank-correlation analysis was conducted to 

determine the intensity of the associations among the storm 

characteristics (appendix E). Because the storm characteristics are generally based on the size and duration of the storm, 

many of these characteristics are strongly correlated, as were 

characteristics of the preceding storm and of the antecedent 

dry period. For example, storm duration (DUR) was significantly correlated with rain duration (RDUR), with a correlation coefficient (ρ) of 0.98 (p-value < 0.0001; n = 72), simply 

meaning that the longer it rained the longer the storm lasted 

(fig. 14). Characteristics of the preceding storms were also 

analyzed using Spearman rank correlation (appendix E). The 

two characteristics of the antecedent dry period, the duration 

of the dry period (DRY) and the number of cars during that 

period (ADT) were strongly correlated (ρ = 0.89; p < 0.0001; 

n = 72) (fig. 15). Because these variables are so strongly 

associated with each other, it is difficult to identify which of 

the variables are the most likely to be factors affecting water 

quality.

Relations among Constituents at Storm Drain C

Spearman’s rank-correlation procedure was used to determine the relationships among the water-quality constituents at 

Storm Drain C (appendix E). Identifying variables that have 

similar patterns of behavior can reduce the number of statistical analyses by allowing the use of a single variable that is 

representative of a larger group. Censored data were recensored to the highest detection limit for each constituent before 

the correlation analysis. This nonparametric method assigns 

the average rank to censored values determined as ties (Helsel, 

2005).

Two groups of constituents were identified as being 

correlated—that is, behaving in similar patterns during runoff 

events at Storm Drain C. The first group (group A) included 

DUR

SDUR PDUR DRY

DISCHARGE, IN CUBIC FEET PER SECOND

0

5

10

15

20

25

30

35

40

BIDIRECTIONAL TRAFFIC COUNT

0

0.1

0.2

0.3

0.4

0.5

0.6

PRECIPITATION, IN INCHES

0

1,000

2,000

3,000

4,000

PRECIPITATION

POINT ON HYDROGRAPH

AT WHICH GRAB SAMPLE

WAS COLLECTED

POINT ON HYDROGRAPH

AT WHICH BOTTLES FILLED

FOR COMPOSITE SAMPLE

DISCHARGE

TRAFFIC

11/24/03

12:00 AM

11/25/03

12:00 AM

11/26/03

12:00 AM

11/27/03

12:00 AM

11/28/03

12:00 AM

11/29/03

12:00 AM

11/30/03

12:00 AM

12/1/03

12:00 AM

EXPLANATION

Figure 13. Example of the time-series data for a storm at Storm Drain C. Discharge, precipitation, traffic, and sampling events are 

shown. Select storm characteristics including the duration of the previous storm (PDUR), the dry period preceding the storm event 

(DRY), the duration of the sampling event (SDUR), and the duration of the storm event (DUR) are delineated by dotted lines.
H-3 Stormwater Data Analysis 35

Table 6. List of storm characteristics and storm-characteristic acronyms used in this study.

[cf, cubic feet; cfs, cubic feet per second; cfm, cubic feet per minute; nov, number of vehicles; >, greater than]

Storm

characteristic 

acronym

Units Storm characteristic description

Storm Event Variables

DUR minutes The duration of the storm determined by using flow data from either Storm Drain C or Xeriscape Garden. 

Measured as the time between the start of flow > 0.10 cfs at Storm Drain C (or 25 cfs at Xeriscape Garden) 

until the final recession of flow when flow returns below 0.10 cfs at Storm Drain C or 25 cfs at Xeriscape 

Garden.

RDUR minutes The duration of rainfall as measured at the Tunnel rain gage for the storm events identified under DUR.

TOTR inches The total rain during the runoff event in inches recorded at the Tunnel rain gage.

Qmax cfs Peak flow in DUR.

Qtwa cfs Time weighted average discharge over DUR.

OINT cfm The overall intensity of the storm determined from the VOL and the DUR.

VOL cf The volume of runoff determined from the mean flow rate and runoff event duration

VOLtwa cf The time-weighted average volume of runoff determined from the Qtwa and the DUR.

IVOL cf The highest intensity of runoff volume during the event determined from Qmax for a 5-minute period.

VDS nov/DUR Total number of vehicles during storm determined from hourly traffic data for time period of the runoff 

duration. Interpolated where necessary between hourly totals.

Sample Event Variables

SDUR minutes The duration of the storm determined by using flow data from either Storm Drain C or Xeriscape Garden. 

Measured as the time between the start of flow > 0.10 cfs at Storm Drain C (or 25 cfs at Xeriscape Garden) 

until the grab sample or the last bottle of the composite sample was collected.

SRDUR minutes The duration of rainfall as measured at the Tunnel rain gage for the storm events identified under SDUR.

SQMax cfs Peak flow in SDUR

SQmaxP cfs The maximum instantaneous discharge measured during the storm prior to the collection of the grab sample or 

first bottle of a composite sample.

SQtwa cfs Time weighted average discharge over SDUR.

SampleQtwa

cfs Time weighted average discharge calculated from time of first composite collection to last composite collection. Instantaneous discharge for grab samples.

SVOLtwa cf The volume of runoff determined from SQtwa and SDUR.

SVDS nov/SDUR Total number of vehicles counted on the highway during the storm determined from hourly traffic data for time 

period of the SDUR.

Preceding Dry Period Variables

DRY hours The duration of antecedent dry period since last runoff event with a rainfall greater than or equal to 0.10 inch.

ADT nov/DRY The total number of vehicles during the antecedent dry period.

Previous Runoff Event Variables

PDUR minutes The duration of preceding runoff event determined as per DUR.

PTOTR inches The total rainfall of preceding runoff event recorded at the Tunnel rain gage.

POINT cfm The overall intensity of the preceding runoff event determined as OINT.

PVOL cf The volume (VOL) of preceding runoff event.

PIVOL cf The highest intensity of volume in the preceding runoff event as determined as IVOL.
36 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

the trace metals cadmium, lead, copper, and zinc; the nutrients total nitrogen, total phosphorus, and total ammonia plus 

organic nitrogen; and the physical properties COD and TSS 

(appendix E, table E-4). Group B included nitrite plus nitrate, 

and the physical properties TDS, specific conductance (lab 

and field), and turbidity (appendix E, table E-5). This would 

suggest that constituents within each group behave in similar 

patterns of buildup and washoff on the highway. The source of 

the group A trace metals is presumably from vehicle emissions 

and vehicle wear and tear. Group A nutrients most likely come 

from materials dislodged from tire treads, materials washed 

off of vehicles, or atmospheric deposition. The group B constituents are more associated with fine sediments, most likely 

derived from materials dislodged or washed off of vehicles as 

well.

Relations among Constituents and Storm 

Characteristics

The relations among the constituents and the storm 

characteristics described above were examined using Spearman rank-correlation (appendix E). All of the correlation 

coefficients in appendix E, table E-6 are negative, indicating 

an inverse relationship between each of the constituents and 

storm characteristics. This means that constituent concentrations decrease in the highway runoff at Storm Drain C as the 

storm characteristics, generally associated with the overall 

size of the storm, increase. As discharge at Storm Drain C 

increased, the group A constituents plotted in similar patterns 

like the one shown for TSS (fig. 16), generally decreasing with 

increased discharge, though with some scatter. However, at 

the other sampling stations, the group A constituents generally 

increased with increasing discharge. The group B constituents 

also plotted in patterns similar to the ones shown for TDS (fig. 

17). Group B constituents at Storm Drain C also tended to 

Table 7. Descriptive statistics for storm characteristics.

[n, number of values; cf, cubic feet; cfs, cubic feet per second; cfm, cubic feet per minute; see table 6 for explanation of acronyms]

Acronym Units n Mean Standard

Deviation Minimum Median Maximum

DUR minutes 72 969 1,114 65 623 4,890

VOLtwa cf 72 126,750 159,290 4,848 59,760 621,911

Qtwa cfs 72 2.2 1.3 0.5 1.8 6.4

QMax cfs 72 18.1 11.3 2.7 17 42

TOTR inches 72 3.1 4.1 0.1 1.2 16.3

RDUR minutes 72 863 1,084 15 443 4,755

VDS nov/DUR 72 26,730 26,256 280.83 15,796 124,110

IVOL cf 72 5,418 3,392 810 5,100 12,600

OINT cfm 72 132.8 76.3 31.8 109.2 385.2

SDUR minutes 72 415 476 3 234 2,513

SVOLtwa cf 72 60,911 86,137 100 24,969 393,723

sQtwa cfs 72 2.7 2 0.1 2.1 8.8

SQMax cfs 72 15.2 11.5 0.3 12 42

TOTRs inches 71 1.8 2.3 0.1 0.8 11.5

SRDUR minutes 70 418 474 15 258 2,505

DRY hours 72 31 45 0.3 9 211

SVDS nov/SDUR 72 11,776 12,786 206 7,886 58,786

ADT nov/DRY 72 50,064 74,792 221 15,185 382,557

PDUR minutes 72 288 319 15 185 1305

PQtwa cfs 72 2.1 3.3 0.3 1.1 13.7

PDURSec seconds 72 17,260 19,152 900 11,100 78,300

PVOLtwa cf 72 59,587 155,441 648 9,990 636,120

POINT cfm 72 128 197.3 15 67.2 820.8

PQMax cfs 72 6.4 8.1 0.8 2.7 30

SQmaxP cfs 72 10.8 9.7 0.3 7.9 41

PIVOL cf 72 1,925 2,433 252 810 9,000
H-3 Stormwater Data Analysis 37

0

1,000

2,000

3,000

4,000

5,000

0 1,000 2,000 3,000 4,000 5,000 6,000

DURATION OF RAIN, IN MINUTES

DURATION OF STORM, IN MINUTES 

0

100,000

200,000

300,000

400,000

0 50 100 150 200 250

ANTECEDENT DRY PERIOD, IN HOURS

NUMBERR OF VEHICLES

Figure 14. Scatter plot displaying the relationship between the duration of the storms (DUR) as measured by 

discharge at Storm Drain C and the duration of rainfall (RDUR) as determined at the Tunnel rain gage.

Figure 15. Scatter plot displaying the relationship between the antecedent dry period and the number of vehicles 

during that period.
TOTAL SUSPENDED SOLIDS,

IN MILLIGRAMS PER LITER

TOTAL SUSPENDED SOLIDS,

IN MILLIGRAMS PER LITER

DISCHARGE, IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND

DISCHARGE, IN CUB

0

1,0002,0003,0004,0005,0006,000

0 400 800 1,200 1,600 2,000

10

STADIUM

0

500

1,0001,5002,0002,500

0 100 200 300 400

10

QUARANTINE STATION

0

500

1,0001,5002,0002,5003,000

0 100 300 

XERISCAPE GARDEN

0

20406080

100120

0 5 10 15 20 25 30

10

STORM DRAIN C

0

200600

1,0001,400

0 200 400 600 800

10

BRIDGE 8

GRA

EXPLAN

COM

Figure 16. XY scatter plots showing the relation between group A constituent total suspended solids and discharge at each station. Das

Minimum Reporting Limit of 10 milligrams per liter.
02040

6080

100120140160

0 400 800 1,200 1,600 2,000

STADIUM

0

20406080

100120

0 100 200 300 400

QUARANTINE STATION

0

20406080

100120

0 100 300 

XERISCAP

0

50

100150200250

0 5 10 15 20 25 30

STORM DRAIN C

0

20406080

100120140

0 200 400 600 800

BRIDGE 8

GRA

EXPLAN

COM

TOTAL DISSOLVED SOLIDS,

IN MILLIGRAMS PER LITER

TOTAL DISSOLVED SOLIDS,

IN MILLIGRAMS PER LITER

DISCHARGE, IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND

DISCHARGE, IN CUB

Figure 17. XY scatter plots showing the relation between group B constituent total dissolved solids and discharge at each station.
40 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

decrease with an increase in discharge, with less scatter than 

the group A constituents. Furthermore, group B constituents 

at the other sampling stations tended to show little change or 

only slight decreases with increasing discharge. The finite 

amount of material that builds up and washes off of the highway surface is progressively more diluted as the volume of the 

storm-driven highway runoff increases. In the stream itself, 

the group A constituents associated with suspended particulate 

matter increase in concentration with increasing stormflow 

because of the increased particulate input caused by an escalation in erosion. The group B constituent concentrations, associated with the dissolved fraction of the stormwater, appear to 

remain relatively unchanged with an increase in stormwater 

volume. This is most likely due to the chemical behavior of 

the constituents, their interactions with other components such 

as pH or hardness, and their geochemical dissolution processes 

(Bricker, 1999).

The storm characteristics that were significantly correlated (p ≤ 0.05) with a majority of the constituents, with 

correlation coefficients greater than 0.50, were the timeweighted average volume calculated over the duration of the 

storm (VOLtwa), the time-weighted average volume calculated over the duration of the sampling period (SVOLtwa), the 

total amount of rain summed over the duration of the storm 

(TOTR), and the total amount of rain summed over the duration of the sampling period (TOTRs). The volume and rainfall 

variables, calculated over different time periods, were correlated. The volume variables were significantly correlated, ρ

= 0.75, p < 0.0001, as were the total rain variables, ρ = 0.81, 

p < 0.0001 (appendix E, table E1). Also, these variables of 

the same time period were significantly correlated: VOLtwa 

and TOTR, ρ = 0.96, p < 0.0001; SVOLtwa and TOTRs, ρ

= 0.92, p < 0.0001 (appendix E, table E1). The correlations 

simply mean that these variables are strongly associated; more 

rain results in greater highway runoff volume. The negative 

correlations of these storm characteristics with the constituent 

concentrations suggests that the larger the volume of water 

(bigger storms) the lower the constituent concentrations at 

Storm Drain C, as discussed earlier. 

Other storm characteristics that were significantly correlated with some of the constituents included (1) the duration of the rainfall (RDUR), which inversely correlated with 

5 of the group A constituents; (2) the peak flow during the 

storm (SQMax), which strongly inversely correlated with the 

group-B constituents; and (3) the overall intensity of the storm 

(OINT), which also strongly inversely correlated with the 

group B constituents. Cadmium was only correlated with the 

volume of the previous storm, which may just be an artifact 

and not a true association between the two variables. This 

analysis shows that there is no single storm characteristic 

strongly associated with the variability of any one of the constituents in the highway runoff at Storm Drain C.

Of note, two antecedent storm characteristics, the correlated variables DRY and ADT (fig. 15), were not identified 

as being significantly correlated with any of the constituents 

in the Spearman rank analysis. It is likely that the buildup of 

material during dry periods was offset by street sweeping and 

that street sweeping was likely to be more frequent the longer 

the dry period. Other studies also found that the duration of the 

dry period was not strongly correlated with stormwater quality 

(Sartor and Boyd, 1972; Driscoll and others, 1990b).

Suggested Modifications to H-3 

Highway Monitoring Program

Since 2001, the USGS has collected water-quality, discharge, and rainfall data during a number of storms at stations 

in the Halawa drainage basin as part of the State of Hawaii 

Department of Transportation’s (HDOT) National Pollutant 

Discharge Elimination System (NPDES) program. The HDOT 

has expressed an interest in continuing this program. This 

section discusses possible modifications to the stormwater 

monitoring program that is currently being conducted by the 

HDOT and the USGS.

Grab Sampling

The stormwater sampling protocol currently in use, as 

described in the HDOT Storm Water Monitoring Plan (State 

of Hawaii Department of Transportation, 2000), calls for a 

combination of grab and composite samples. For at least a 

few storms each year, individual grab samples collected in 

bottles by the automatic samplers could be analyzed separately 

instead of combined as a single composite sample. The grab 

samples provide important information on the water quality at 

the time of sampling, but because of the logistics involved in 

getting to the sampling stations during storms, grab samples 

are usually collected late in the storm, after the peak discharge 

has occurred. Composite samples span the duration of the 

storm but provide only one value, the event mean concentration (EMC), for a storm. The EMC is sufficient when the 

objective is to determine the overall load of the storm, but 

the discrete constituent concentrations, over the course of the 

storm, are lost. Additionally, the State of Hawaii Department 

of Health (HDOH) standards are based on concentrations and 

not loads. 

By analyzing discrete samples from the automatic 

sampler, it is possible to get a clear profile of the storm, from 

first flush to the end of storm-related runoff. Additionally, 

the EMC can be calculated from the discrete samples, but the 

individual sample concentrations cannot be determined from 

the composite-sample concentration. Data collection using 

discrete samples was done by Timperley and others (2005). 

Harmel and others (2006) point out that discrete sampling 

can provide an accurate depiction of temporal variability of 

constituent concentrations during the storm, but it can also 

increase the uncertainty of the water-quality data, especially 

in large or lengthy storms if the sampler runs out of sampling 

bottles. However, the composite sampling they discuss is per-
Suggested Modifications to H-3 Highway Monitoring Program 41

formed by the automatic sampler itself, continuously adding 

multiple aliquots to individual bottles to increase the length 

of sampling period. In the current study, the flow-weighted 

compositing of the discrete samples is performed in the laboratory and not by the automatic point samplers, but the chance 

of running out of sampling bottles is the same. The samplers 

are set to increase the time interval if the storm continues after 

collecting half of the bottles (State of Hawaii Department of 

Transportation, 2000). Harmel and others (2006) recommend 

composite sampling when there is a need to limit the number 

of samples collected or if the study objective is to determine 

the storm loadings and not the within-storm variability. As a 

possible alternative they suggest collecting discrete samples 

for a period of time to gather data on within-storm constituent 

behavior and seasonal trends and then switching to composite 

sampling once this baseline information is acquired. 

Other Suggestions

If this program continues, the following changes to the 

current program could be considered:

1. Add dissolved fractions of metals to the sampling plan. 

The HDOH standards for trace metals are designed for 

the dissolved fraction. Currently, only the total metals are analyzed. By law (40 CFR 122.45), analysis of 

whole-water samples is required for monitoring within 

the NPDES permit. The advantages and disadvantages of 

whole water versus dissolved (filtered) water sampling 

are thoroughly discussed in Breault and Granato (2000). 

Aquatic organisms are more affected by the dissolved 

fraction of potentially toxic contaminants (Gélinas and 

others, 1998; DeCarlo and others, 2004). Bricker (1999) 

presented a complete overview on the major processes 

driving geochemical interactions and concluded:

“If the analyses are incomplete for the major dissolved constituents (even though these may not be 

of interest from the toxics standpoint), it will not 

be possible to evaluate the behavior of the contaminant species in terms of solubilities, speciation, 

complexing, sorption, ion exchange, ion pairing, 

mobilization, and transport—all of the processes that 

determine toxicity and bioavailability. Analyses of 

samples only for the total concentrations of selected 

elements of interest provide, at best, limited information and almost certainly will give a misleading 

picture about the effects of those elements on the 

ecosystem.” 

2. Install an automatic sampler at Bridge 8. This would 

allow for a more accurate comparison between the highway runoff, measured at Storm Drain C, and the runoff 

from the surrounding undeveloped basin, measured at 

Bridge 8. The relations between these sites and the composition of the stormwater runoff passing through them 

are important to understand. Most of the grab samples 

collected at Bridge 8 were taken well after the automatic 

sampler at Storm Drain C had already been triggered. 

The triggering of the automatic sampler at Storm Drain 

C alerts the USGS personnel that a sample is being collected. They then must travel to the stations to collect 

the samples. Storms often occurred late at night, and the 

grab-sampling collection did not start until early the next 

morning. More often than not, the Bridge 8 samples are 

collected well after peak discharge has occurred and discharge is decreasing. These samples are not representative 

of the constituent concentrations during the critical first 

flush and rising-discharge flows and can bias the analyses. 

If a storm is too short in duration, by the time USGS personnel arrive, there may not be adequate runoff to sample 

at Bridge 8. The installation of an automatic sampler 

would greatly improve the timeliness of the sampling.

3. Conduct a one-time sampling of soils upstream of Bridge 

8. Some of the particulate matter that collects on the 

elevated highway is most likely being wind-blown into the 

adjacent forested drainage basin and eventually is being 

transported by overland runoff into the stream. It is suggested that a series of transects perpendicular to the highway and extending out into the basin be established and 

that soil samples be collected at points along the transects 

outward from the highway. These soil samples would be 

analyzed for certain constituents, such as trace elements, 

that would most likely have originated from the highway. Sampling at points at a range of distances from the 

highway would provide information about the constituent 

concentrations being accumulated and the distances that 

they travel. This information would help determine the 

source of these constituents reported in Bridge 8 samples.

4. Collect samples during low-flow conditions. Harmel and 

others (2006) recommend that low-flow water-quality 

samples be collected at regular intervals to determine 

instream concentration variability. Routine low-flow 

sampling aids in quantifying point source contributions, 

shallow surface return flow, and constituent release from 

instream processes (Harmel and others, 2006). North Halawa Stream is intermittent; therefore, low-flow sampling 

would only occur during those periods between storms 

while the stream is still flowing. Data from samples collected during low-flow conditions would provide valuable 

information about the water quality of the stream absent 

any input from Storm Drain C. 

5. Add two metals to the sampling plan—chromium and 

nickel. This would increase lab analysis cost by a minimal 

amount. These two metals are relevant to highway runoff 

and have been sampled in the past. Although previous 

studies in Hawaii have determined that nickel concentrations in roadway stormwater are not significantly 

different from naturally occurring levels (De Carlo and 

Spencer, 1997; Sutherland and others, 2000; De Carlo 

and Anthony, 2002; De Carlo and others, 2004), it is still 
42 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

important to monitor nickel concentrations to verify that 

anthropogenic inputs remain low.

6. Eliminate fecal coliform and biochemical oxygen demand 

(BOD) analyses from the sampling plan. Because the H-3 

Highway is elevated and therefore not exposed to overland runoff, these two constituents, produced from organic 

input such as livestock or human sewage effluents, would 

not be expected to impact the highway stormwater runoff.

7. Conduct a study to examine the efficiency of the highway street sweeping. Also, keep a record of the dates and 

times when street sweeping is conducted on the highway 

between the Trans-Koolau Tunnels and Storm Drain C.

Summary and Conclusions

Concerns regarding water quality are important issues 

at the Federal, State, and local levels in all communities. The 

quality of the Nation’s fresh waters can affect the quality of 

life for the general public. The quality of stormwater runoff 

that drains into the stream network is of critical importance 

to managers and regulatory agencies. The U.S. Geological 

Survey, in cooperation with the State of Hawaii Department of 

Transportation (HDOT) and the Federal Highway Administration, has been monitoring stormwater quality using a network 

of five stations in the Halawa Stream basin, on Oahu, Hawaii. 

This report describes the quality of stormwater sampled 

from water year 1999 through water year 2004. The network 

includes four stations on North Halawa Stream known as 

Bridge 8, Xeriscape Garden, Quarantine Station, and Stadium. 

The network also includes a station at Storm Drain C, which 

drains stormwater runoff from the H-3 Highway. Sampling 

during storms at three stations, Storm Drain C, Xeriscape Garden, and Quarantine Station, was facilitated using automatic 

point samplers that were used to collect composite samples. 

Individual grab samples were collected at all five sampling stations and were not composited. Quality-assurance and qualitycontrol samples also were collected to help evaluate potential 

sources of contamination and inaccurate results.

Selected water-quality data were compared to the State 

of Hawaii Department of Health (HDOH) water-quality 

standards to determine the effects of highway storm runoff on 

the water quality of the affected streams. Because the HDOH 

criteria were not designed for stormwater sampling, these 

comparisons are simply meant to provide a point of reference 

for the stormwater results. The geometric mean and concentrations not to be exceeded 10 percent and 2 percent of the 

time were used as numeric standards for five water-quality 

constituents—total nitrogen, nitrite plus nitrate, total phosphorus, total suspended solids, and turbidity. These standards 

also vary depending on the season, with the wet-season values 

higher than the dry-season values. The remaining standards 

consist of a single numeric criterion not to be exceeded, except 

for water temperature and pH, for which the standards depend 

on deviations from ambient conditions. For constituents with 

data determined to be below the minimum reporting levels, 

the robust approach to “regression on order statistics” (Robust 

ROS) was used to determine the numeric values for comparison to the standards. Most of the HDOH standards were 

exceeded at most sampling stations, most likely because of the 

bias inevitably introduced by stormwater samples.

The “first flush” phenomenon, in which constituent concentrations are higher at the beginning of storm runoff events 

and gradually decrease over the course of the storm, was 

observed at Storm Drain C. An analysis of discrete samples 

collected by the automatic point sampler at Storm Drain C 

during the storm of April 20, 2002, showed that concentrations 

were initially high during the period of increasing discharge, 

before peak discharge, and decreased over the remainder of 

the storm for the trace metals cadmium, lead, zinc, and copper, 

and a similar pattern was shown for specific conductance.

The H-3 Highway is a large source of metals to Halawa 

Stream relative to the surrounding areas, but it is a small 

source of nutrients and sediments. The drainage basin for 

Bridge 8 does not include the H-3 Highway; therefore, water 

quality at Bridge 8 is unaffected by highway runoff. Higher 

concentrations and loads of nutrients and dissolved and suspended solids at Bridge 8, relative to Storm Drain C, indicate 

that the undeveloped drainage basin of Bridge 8 has a larger 

effect on nutrient and sediment quality in North Halawa 

Stream than the highway. In contrast, the lower concentrations 

and loads of metals at Bridge 8, relative to Storm Drain C, 

indicate that the undeveloped drainage basin of Bridge 8 has 

a smaller effect on metals in North Halawa Stream than the 

highway.

Most constituent concentrations and loads in stormwater 

runoff increase in a downstream direction from Xeriscape 

Garden to Quarantine station, although results from individual 

storms may vary. This general trend indicates that the part of 

the drainage basin of Quarantine station that is downstream 

of Xeriscape Garden is enriched with nutrients and trace 

metals. This area contains a light industrial area that may be 

a source of some of these constituents. The total suspended 

solids (TSS), total dissolved solids (TDS), and nutrient concentrations at these downstream sites were higher than those 

in Storm Drain C. Because the discharge at Storm Drain C 

generally is a small fraction of the total discharge in North 

Halawa Stream, the stormwater runoff from the H-3 Highway 

contributes only a small fraction of the total storm loads of 

TSS, TDS, and nutrients in North Halawa Stream. The storm 

yields of these constituents from Storm Drain C, however, are 

comparable to or higher than the yields measured at Xeriscape 

Garden and Quarantine station. Thus, per unit area, the H-3 

Highway contributes comparable amounts of some constituents to North Halawa Stream as the surrounding areas. 

Water-quality data presented in this report indicate that 

the timing of sample collection is an important factor controlling constituent concentrations in stormwater runoff samples. 

During a storm, constituent concentrations commonly attain 

peak values during the initial period of increasing discharge, 
References Cited 43

before peak discharge occurs. This period of increasing 

discharge can be very short because of the flashy nature of 

North Halawa Stream. Thus, automatic samplers are needed to 

best characterize water quality in stormwater runoff. Analyses 

of grab samples collected during the periods of decreasing 

discharge provide indications of water quality during the latter 

parts of storms, but generally underestimate mean constituent concentrations during storms. Flow-weighted composite 

samples provide better estimates of mean constituent concentrations during storms. 

The H-3 Highway may contribute different constituents 

to stormwater runoff than does the surrounding area. Because 

suspended sediments in North Halawa Stream mainly are 

derived from erosion of soils, the primary source areas of suspended sediments are unpaved areas within the valley and not 

the H-3 Highway. Thus, unpaved areas may represent a main 

source of some nutrients in stormwater runoff. In contrast, the 

highway may represent a main source of trace metals, such as 

cadmium, copper, lead, and zinc, which are commonly associated with tire wear, brake linings, vehicle fluids or lubricants, 

or emissions.

References Cited

Andrews, S., and Sutherland, R.A., 2004, Cu, Pb and Zn contamination in Nuuanu watershed, Oahu, Hawaii: Science of 

the Total Environment, v. 324, p. 173-182.

Barber, M.E., Brown, M.G., Lingenfelder, K.M., and Yonge, 

D.R., 2006, Phase I; Preliminary environmental investigation of heavy metals in highway runoff: Washington State 

Transportation Center, Washington State University, Final 

report, 38 p.

Barrett, M.E., Malina, J.F., Jr., Charbeneau, R.J., and Ward, 

G.H., 1995a, Water quality and quantity impacts of highway construction and operation; summary and conclusions: 

Center for Research in Water Resources Technical Report 

266, Bureau of Engineering Research, University of Texas 

at Austin, 35 p.

Barrett, M.E., Zuber, R.D., Collins III, E.R., Malina Jr., J.F., 

Charbeneau, R.J., and Ward, G.H., 1995b, A review and 

evaluation of literature pertaining to the quantity and control 

of pollution from highway runoff and construction: Center 

for Research in Water Resources Technical Report 239, 

Bureau of Engineering Research, University of Texas at 

Austin, 140 p.

Beltran, V.L., and De Carlo, E.H., 2005, Storm-driven variability of particulate metal concentrations in streams of a 

subtropical watershed, in Lichffouse, E., Schwarzbauer, 

J., and Robert, D., eds., Environmental Chemistry: Berlin 

Heidelberg, Springer, p. 153-175.

Bevenue, A., Hylin, J.W., Kawano, Y., and Kelley, T.W., 1972, 

Organochlorine pesticide residues in water, sediment, algae, 

and fish, Hawaii—1970-71: Pesticides Monitoring Journal, 

v. 6, p. 56-64.

Blumenstock, D.I., and Price, S., 1967, Climates of the 

states—Hawaii: U.S. Department of Commerce, Environmental Science Services Administration, Climatography of 

the United States no. 60-51, 27 p.

Brasher, A.M., and Anthony, S.S., 2000, Occurrence of 

organochlorine pesticides in stream bed sediment and fish 

from selected streams on the island of Oahu, Hawaii, 1998: 

U.S. Geological Survey Fact Sheet 140-00, 6 p.

Brasher, A.M.D., and Wolff, R.H., 2004, Relations between 

land use and organochlorine pesticides, PCBs, and semivolatile organic compounds in streambed sediment and fish 

on the island of Oahu, Hawaii: Archives of Environmental 

Contamination and Toxicology, v. 46, p. 385-398.

Breault, R.F., and Granato, G.E., 2000, A synopsis of technical 

issues of concern for monitoring trace elements in highway 

and urban runoff: U.S. Geological Survey Open-File Report 

00-422, 67 p.

Bricker, O.P., 1999, An overview of the factors involved in 

evaluating the geochemical effects of highway runoff on 

the environment: U.S. Geological Survey Open-File Report 

98-630, 30 p.

Britton, L.J., and Greeson, P.E., eds., 1989, Methods for collection and analysis of aquatic biological and microbiological samples: U.S. Geological Survey Techniques of WaterResources Investigations, book 5, chap. A4, 363 p.

Buchanan, T.J., and Somers, W.P., 1969, Discharge measurements at gaging stations: U.S. Geological Survey Techniques of Water-Resources Investigation 03-A8, 65 p.

Childress, C.J.O., Foreman, W.T., Connor, B.F., and Maloney, T.J., 1999, New reporting procedures based on longterm method detection levels and some considerations for 

interpretations of water-quality data provided by the U.S. 

Geological Survey National Water Quality Laboratory: U.S. 

Geological Survey Open-File Report 99-193, 19 p.

Chow, T.J., and Earl, J.L., 1972, Lead isotopes in North 

American coals: Science, v. 176, p. 510-511.

Dalrymple, T., and Benson, M.A., 1968, Measurement of peak 

discharge by the slope-area method: U.S. Geological Survey 

Techniques of Water-Resources Investigation 03-A2, 12 p.

De Carlo, E.H., and Anthony, S.S., 2002, Spatial and temporal 

variability of trace element concentrations in an urban subtropical watershed, Honolulu, Hawaii: Applied Geochemistry, v. 17, p. 475-492.
44 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

De Carlo, E.H., and Spencer, K.J., 1995, Records of lead and 

other heavy metal inputs to sediments of the Ala Wai Canal, 

Oahu, Hawaii: Pacific Science, v. 49, p. 471-491.

De Carlo, E.H., and Spencer, K.J., 1997, Retrospective analysis of anthropogenic inputs of lead and other heavy metals 

to the Hawaiian sedimentary environment: Applied Organometallic Chemistry, v. 11, p. 415-437.

De Carlo, E.H., Beltran, V.L., and Tomlinson, M.S., 2004, 

Composition of water and suspended sediment in streams 

of urbanized subtropical watersheds in Hawaii: Applied 

Geochemistry, v. 19, p. 1011-1037.

De Carlo, E.H., Tomlinson, M.S., and Anthony, S.S., 2005, 

Trace elements in streambed sediments of small subtropical 

streams on Oahu, Hawaii; results from the USGS NAWQA 

program: Applied Geochemistry, v. 20, p. 2157-2188.

DeVito, P.A., Dugan, G.L., Murabayashi, E.T., and Gee, H.K., 

1995, Nonpoint source pollution within the Anahulu River 

and ‘Opae‘ula Stream drainage areas, Kaiaka-Waialua Bay 

hydrologic unit area, O‘ahu, Hawai‘i: University of Hawaii 

Water Resources Research Center Project Report PR-95-11, 

81 p.

Driscoll, E.D., Shelley, P.E., and Strecker, E.W., 1990a, 

Pollutant loadings and impacts from highway stormwater 

runoff, Volume I—Design Procedure: U.S. Department of 

Transportation, Federal Highway Administration, FHWARD-88-006, 61 p.

Driscoll, E.D., Shelley, P.E., and Strecker, E.W., 1990b, Pollutant loadings and impacts from highway stormwater runoff, 

Volume III—Analytical investigation and research report: 

U.S. Department of Transportation, Federal Highway 

Administration, FHWA-RD-88-008, 150 p.

East, J.W., Paul, E.M., and Porter, S.D., 1998, Nutrient loading 

and selected water-quality and biological characteristics 

of Dickinson Bayou near Houston, Texas, 1995-97: U.S. 

Geological Survey Water-Resources Investigations Report 

98-4012, 50 p.

Eshelman, A.M., 1973, A preliminary survey of lead and mercury in the Hawaiian environment: Honolulu, University of 

Hawaii at Manoa, Ph.D. dissertation, 154 p.

Fishman, M.J., ed., 1993, Methods of analysis by the U.S. 

Geological Survey National Water Quality Laboratory—

Determination of inorganic and organic constituents in 

water and fluvial sediments: U.S. Geological Survey OpenFile Report 93-125, 217 p.

Fishman, M.J., and Friedman, L.C., eds., 1989, Methods for 

determination of inorganic substances in water and fluvial 

sediments (3d ed.): U.S. Geological Survey Techniques of 

Water-Resources Investigations, book 5, chap. A1, 545 p.

Foote, D.E., Hill, E.L., Nakamura, S., and Stephens, F., 1972, 

Soil survey of the islands of Kauai, Oahu, Maui, Molokai, 

and Lanai, State of Hawaii: U.S. Department of Agriculture, 

Soil Conservation Service, 232 p.

Friedman, L.C., and Erdmann, D.E., 1982, Quality assurance 

practices for the chemical and biological analyses of water 

and fluvial sediments: U.S. Geological Survey Techniques 

of Water Resources Investigations, book 5, chapter A6, 

181 p.

Fujiwara, T.O., 1973, Characterization of urban stormwater 

discharges from separate storm sewers: Honolulu, University of Hawaii at Manoa, Master’s thesis, 161 p.

Gélinas, Y., Barnes, R.M., Florian, D., and Schmit, J., 1998, 

Acid leaching of metals from environmental particles; 

expressing results as a concentration within the leachable 

fraction: Environmental Science and Technology, v. 32, p. 

3622-3627.

Giambelluca, T.W., Nullet, M.A., and Schroeder, T.A., 1986, 

Rainfall atlas of Hawaii: State of Hawaii, Department of 

Land and Natural Resources, Report R76, 267 p.

Gilliom, R.J., and Helsel, D.R, 1986, Estimation of distributional parameters for censored trace-level water quality data, 

I. estimation techniques: Water Resources Research, 

v. 22, no. 2, p. 135-146.

Harmel, R.D., King, K.W., Haggard, B.E., Wren, D.G., and 

Sheridan, J.M., 2006, Practical guidance for discharge and 

water quality data collection on small watersheds: Transactions of the ASABE, v. 49, p. 937-948.

Harned, D.A., 1988, Effects of highway runoff on streamflow 

and water-quality in the Sevenmile Creek basin, a rural area 

in the Piedmont Province of North Carolina, July 1981 to 

July 1982: U.S. Geological Survey Water Supply Paper 

2329, 33 p.

Helsel, D.R., 1990, Less than obvious—statistical treatment of 

data below the detection limit: Environmental Science and 

Technology, v. 24, no. 12, p. 1766-1774.

Helsel, D.R., 2005, Nondetects and data analysis—statistics 

for censored environmental data: New York, John Wiley and 

Sons, 250 p.

Helsel, D.R., and Cohn, T.A., 1988, Estimation of descriptive 

statistics for multiply censored water quality data: Water 

Resources Research, v. 24, no. 12, p. 1997-2004.

Helsel, D.R., and Gilliom, R.J., 1986, Estimation of distributional parameters for censored trace-level water quality data, 

II. Verification and applications: Water Resources Research, 

v. 22, no. 2, p. 147-155.

Helsel, D.R., and Hirsch, R.M., 1992, Statistical methods in 

water resources: Amsterdam, Elsevier, Studies in Environmental Science 49, 522 p.
References Cited 45

Hill, B.R., Fontaine, R.A., Taogoshi, R.I., and Teeters, P.C., 

2000, Water resources data, Hawaii and other Pacific areas, 

water year 1999, Vol. 1, Hawaii: U.S. Geological Survey 

Water-Data Report HI-99-1, 339 p.

Hinds, N.E.A., 1925, Amphitheater valley heads: Journal of 

Geology, v. 33, p. 816-818.

Hoffman, E.J., Latimer, J.S., Hunt, C.D., Mills, G.L., and 

Quinn, J.G., 1985, Stormwater runoff from highways: 

Water, Air, and Soil Pollution, v. 25, p. 349-364.

Hoover, D.J., 2002, Fluvial nitrogen and phosphorus in 

Hawaii; storm runoff, land use, and impacts on coastal 

waters: Honolulu, University of Hawaii at Manoa, Ph.D. 

dissertation, 437 p.

Horner, R.R., and Mar, B.W., 1983, Guide for assessing waterquality impacts of highway operations and maintenance, 

Transportation Research Record 948, p. 31-40.

Howell, R.B., 1978, Water pollution aspects of particles that 

collect on highway surfaces: Sacramento, California Department of Transportation, FHWA-CA-78-22, 140 p.

Hunt, C.D. Jr., 1996, Geohydrology of the Island of Oahu, 

Hawaii: U.S. Geological Survey Professional Paper 1412-B, 

54 p.

Hunter, C.L., Stephenson, M.D., Tjeerdema, R.S., Crosby, 

D.G., Ichikawa, G.S., Goetz, J.D., Paulson, K.S., Crane, 

D.B., Martin, M., and Newman, J.W., 1995, Contaminants 

in oysters in Kaneohe Bay, Hawaii: Marine Pollution Bulletin, v. 30, p. 646-654.

Iman, R.L., and Conover, W.J., 1983, A modern approach to 

statistics: New York, John Wiley and Sons, 497 p.

Irish, L.B., Jr., Lesso, W.G., Barrett, M.E., Malina, J.F., Jr., 

Charbeneau, R.J., and Ward, G.H., 1995, An evaluation of 

the factors affecting the quality of highway runoff in the 

Austin, Texas area: Center for Research in Water Resources 

Technical Report 264, Bureau of Engineering Research, 

University of Texas at Austin, 236 p.

Irish, L.B., Jr., Barrett, M.E., Malina, J.F., Jr., Charbeneau, 

R.J., 1998, Use of regression models for analyzing highway 

storm-water loads: Journal of Environmental Engineering, 

v. 124, no. 10, p. 987-993.

Izuka, S.K., 1992, Geology and stream infiltration of North 

Halawa Valley, Oahu, Hawaii: U.S. Geological Survey 

Water-Resources Investigations Report 91-4197, 21 p.

Jernigan, E.L., Ray, B.J., and Duce, R.A., 1971, Lead and 

bromine in atmospheric particulate matter on Oahu, Hawaii: 

Atmospheric Environment, v. 5, p. 881-886.

Laws, E.A., and Ferrentinos, L., 2003, Human impacts on 

fluxes of nutrients and sediment in Waimanalo Stream, 

Oahu, Hawaiian Islands: Pacific Science, v. 57, p. 119-140.

Lopes, T.J., and Furlong, E.T., 2001, Occurrence and potential adverse effects of semivolatile organic compounds in 

streambed sediment, United States, 1992-1995: Environmental Toxicology and Chemistry, v. 20, p. 727-737.

Mink, J.F., 1960, Distribution pattern of rainfall in the leeward 

Koolau Mountains, Oahu, Hawaii: Journal of Geophysical 

Research, v. 65, no. 9, p. 2869–2876.

Nowell, L.H., Capel, P.D., and Dileanis, P.D., 1999, Pesticides 

in stream sediment and aquatic biota—distribution, trends, 

and governing factors: Boca Raton, Fla., CRC Press, Pesticides in the Hydrologic System series, vol. 4, 1040 p.

Owenby, J.R., and Ezell, D.S., 1992, Monthly station normals of temperature, precipitation, and heating and cooling degree days 1961-90: Asheville, North Carolina, U.S. 

Department of Commerce, National Oceanic and Atmospheric Administration, National Climatic Data Center, 

Climatography of the United States no. 81, 26 p.

Presley, T.K., 2001, Rainfall, streamflow, and water-quality 

data during stormwater monitoring, Halawa Stream drainage basin, Oahu, Hawaii, July 1, 2000 to June 30, 2001: 

U.S. Geological Survey Open-File Report 01-256, 11 p.

Presley, T.K., 2002, Rainfall, streamflow, and water-quality 

data during stormwater monitoring, Halawa Stream drainage basin, Oahu, Hawaii, July 1, 2001 to June 30, 2002: 

U.S. Geological Survey Open-File Report 02-319, 47 p. 

Pritt, J.W., and Raese, J.W., eds., 1992, Quality assurance/

quality control manual, National Water Quality Laboratory: 

U.S. Geological Survey Open-File Report 94-708, 26 p.

Rantz, S.E., and others, 1982, Measurement and computation 

of streamflow, Volume 1. Measurement of stage and discharge; Volume 2. Computation of discharge: U.S. Geological Survey Water-Supply Paper 2175, 284 p. and 346 p.

Sartor, J.D., and Boyd, G.B., 1972, Water pollution aspects of 

street surface contaminants: Washington, DC, U.S. Environmental Protection Agency, Report No. EPA-R2-72/081.

SAS Institute, 1990, SAS® procedures guide, version 6, 3rd

edition: Cary, North Carolina, SAS Institute Inc., 705 p.

Schmitt, C.J., and Brumbaugh, W.G., 1990, National contaminant biomonitoring program; concentrations of arsenic, 

cadmium, copper, lead, mercury, selenium, and zinc in U.S. 

freshwater fish, 1976-1984: Archives of Environmental 

Contamination and Toxicology, v. 19, p. 731-747.

Schmitt, C.J., Ludke, J.L., and Walsh, D.F., 1981, Organochlorine residues in fish—National Pesticide Monitoring 

Program, 1970-74: Pesticides Monitoring Journal, v. 14, p. 

136-206.
46 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

Schmitt, C.J., Zajicek, J.L., and Ribick, M.A., 1985, National 

pesticide monitoring program; residues of organochlorine 

chemicals in freshwater fish, 1980-81: Archives of Environmental Contamination and Toxicology, v. 14, p. 225-260.

Shelton, L.R., 1994, Field Guide for collecting and processing 

stream-water samples of the National Water Quality Assessment Program: U.S. Geological Survey Open- File Report 

94-455, 42 p.

Shimizu, B.H., Nishimoto, D.C., Taogoshi, R.I., and Teeters, 

P.C., 2005, Water resources data, Hawaii and other Pacific 

areas, water year 2004: U.S. Geological Survey Water-Data 

Report HI-04-1, 333 p.

Shumway, R.H., Azari, R.S., and Kayhanian, M., 2002, Statistical approaches to estimating mean water quality concentrations with detection limits: Environmental Science and 

Technology, v. 36, p. 3345-3353.

Smith, J.A., Witkowski, P.J., and Fusillo, T.V., 1988, Manmade organic compounds in the surface waters of the 

United States—a review of current understanding: U.S. 

Geological Survey Circular 1007, 92 p.

Sneck-Fahrer, D.A., Milburn, M.S., East, J.W., and Oden, 

J.H., 2005, Water-quality assessment of Lake Houston near 

Houston, Texas, 2000-2004: U.S. Geological Survey Scientific Investigations Report 2005-5241, 55 p.

Spear, R.L., 1990, North Halawa Valley—a progress report 

on the archaeological fieldwork conducted within the H-3 

Highway corridor, Oahu Island, Hawaii: Honolulu, Hawaii, 

Applied Research Group, Bishop Museum, 18 p.

State of Hawaii Department of Business, Economic Development and Tourism, 2005, The State of Hawaii data 

book—2004, a statistical abstract: Honolulu, Hawaii, 985 p.

State of Hawaii Department of Health, 2000, Hawaii Administrative Rules, Title 11, chap. 54, Water Quality Standards, 

p.54-1 to 54-61, as approved April 7, 2000.

State of Hawaii Department of Transportation, 2000, Storm 

water monitoring program plan, prepared by Belt Collins 

Consultants, 20 p., 1 appendix.

State of Hawaii Department of Transportation, 2002, Storm 

water monitoring report 2001-2002, prepared by Belt Collins Consultants, 22 p., 23 appendixes.

State of Hawaii Department of Transportation, 2003, Storm 

water monitoring report 2002-2003, prepared by Belt Collins Consultants, 26 p. 22 appendixes.

State of Hawaii Department of Transportation, 2004, Storm 

water monitoring report 2003-2004, prepared by Belt Collins Consultants, 26 p. 22 appendixes.

Sutherland, R.A., 2000, Bed sediment-associated TE’s in an 

urban stream, Oahu, Hawaii: Environmental Geology, v. 39, 

p. 611-627.

Sutherland, R.A., and Tolosa, C.A., 2000, Multi-element 

analysis of road-deposited sediment in an urban drainage 

basin, Honolulu, Hawaii: Environmental Pollution, v. 110, 

p. 483-495.

Sutherland, R.A., Tolosa, C.A., Tack, F.M., and Verloo, M.G., 

2000, Characterization of selected element concentrations 

and enrichment ratios in background and anthropogenically 

impacted roadside areas: Archives of Environmental Contamination and Toxicology, v. 38, p. 428-438.

Sutherland, R.A., Day, J.P., and Bussen, J.O., 2003, Lead concentrations, isotope ratios, and source apportionment in road 

deposited sediments, Honolulu, Oahu, Hawaii: Water, Air, 

and Soil Pollution, v. 142, p. 165-186.

Sylvester, M.A., Kister, L.R., and Garrett, W.B., 1990, Guidelines for the collection, treatment, and analysis of water 

samples—U.S. Geological Survey Western Region Field 

Manual: U.S. Geological Survey, Water Resources Division, 

Western Region Internal Report, 144 p.

Takasaki, K.J., Hirashima, G.T., and Lubke, E.R., 1969, Water 

resources of windward Oahu, Hawaii: U.S. Geological Survey Water-Supply Paper 1894, 119 p.

Tanita, R., Johnson, J.M., Chun, M., and Maciolek, J., 1976, 

Organochlorine pesticides in the Hawaii Kai marina, 

1970-74: Pesticides Monitoring Journal, v. 10, p. 24-30.

Taogoshi, R.I., Nishimoto, D.C., Fontaine, R.A., Wong, M.F., 

and Hill, B.R., 2001, Water resources data, Hawaii and 

other Pacific areas, water year 2000: U.S. Geological Survey Water-Data Report HI-00-1, 398 p.

Taogoshi, R.I., Wong, M.F., Nishimoto, D.C., and Teeters, 

P.C., 2002, Water resources data, Hawaii and other Pacific 

areas, water year 2001: U.S. Geological Survey Water-Data 

Report HI-01-1, 398 p.

Tasker, G.D., and Granato, G.E., 2000, Statistical approaches 

to interpretation of local, regional, and national highwayrunoff and urban-stormwater data: U.S. Geological Survey 

Open-File Report 00-491, 59 p.

Teeters, P.C., Taogoshi, R.I., Nishimoto, D.C., and Shimizu, 

B.H., 2005, Water resources data, Hawaii and other Pacific 

areas, water year 2003: U.S. Geological Survey Water-Data 

Report HI-03-1, 390 p.

Terrio, P.J., 1995, Water-quality assessment of the upper 

Illinois River basin in Illinois, Indiana, and Wisconsin; 

nutrients, dissolved oxygen, and fecal-indicator bacteria 

in surface water, April 1987 through August 1990: U.S. 

Geological Survey Water-Resources Investigations Report 

95-4005, 79 p.
References Cited 47

Timme, P.J., 1995, National Water Quality Laboratory 1995 

Services Catalog: U.S. Geological Survey Open-File Report 

95-352, p. 92.

Timperley, M., Williamson, B., Mills, G., Horner, B., and 

Hasan, M.Q., 2005, Sources and loads of metals in urban 

stormwater: Prepared for the Auckland Regional Council, 

NIWA Client Report, AKL2004-070, 78 p.

U.S. Census Bureau, 2007, Annual estimates of the population for counties of Hawaii; April 1, 2000 to July 1, 2005: 

[http://quickfacts.census.gov/qfd/states/15000lk.html, 

accessed on February 6, 2007].

U.S. Department of Transportation, Federal Highway Administration, and State of Hawaii Department of Transportation, 1987, Final third supplement to the Interstate Route 

H-3 Environmental Impact Statement, Interstate Route H-3 

Halawa to Halekou Interchange: Report Number FHWAHI-EIS-87-01-F(S), various pagination.

U.S. Environmental Protection Agency, 1993, NPDES storm 

water sampling guidance manual, prepared by C.K. Smoley: 

CRC Press, Inc. 165 p.

U.S. Environmental Protection Agency, 2006, National 

recommended water quality criteria: U.S. Environmental 

Protection Agency, Office of Water, Office of Science and 

Technology, 24 p.

Wagner, K.J., and Mitchell, D.F., 1987, Size fractionation of 

pollutants as a lake management tool, Annual Meeting for 

North American Lake Management Society, Orlando, FL.

Ward, J.R., and Harr, C.A., eds., 1990, Methods for collection 

and processing of surface-water and bed material samples 

for physical and chemical analyses: U.S. Geological Survey 

Open-File Report 90-140, 71 p.

Wentworth, C.K., 1942, Geology and ground-water resources 

of the Moanalua-Halawa District: Honolulu Board of Water 

Supply, 156 p.

Wentworth, C.K., 1943, Soil avalanches on Oahu, Hawaii: 

Bulletin of the Geological Society of America, v. 54, p. 

53–64.

Wershaw, R.L., Fishman, M.J., Grabbe, R.R., and Lowe, L.E., 

1987, Methods for the determination of organic substances 

in water and fluvial sediments: U.S. Geological Survey 

Techniques of Water Resources Investigations, book 5, 

chapter A3, 80 p.

Wong, C.S., Capel, P.D., and Nowell, L.H., 2000, Organochlorine pesticides and PCBs in stream sediment and aquatic 

biota—initial results from the National Water-Quality 

Assessment Program, 1992-1995: U.S. Geological Survey 

Water-Resources Investigations Report 00-4053, 88 p.

Wong, M.F., 2004, Water quality in the Halawa, Haiku, and 

Kaneohe drainage basins before, during, and after H-3 

Highway construction, Oahu, Hawaii, 1983–99: U.S. Geological Survey Scientific Investigations Report 2004-5002, 

45 p.

Wong, M.F., and Hill, B.R., 1992, Statistical summary of 

hydrologic and water-quality data from the North Halawa, 

Haiku, and Kamooalii drainage basins, Oahu, Hawaii, water 

years 1983–89: U.S. Geological Survey Water-Resources 

Investigations Report 92-4049, 52 p.

Wong, M.F., and Yeatts, D.S., 2002, Streamflow and 

suspended-sediment loads before, during, and after H-3 

Highway construction, North Halawa, Haiku, South Fork 

Kapunahala, and Kamooalii drainage basins, Oahu, Hawaii, 

1983—99: U.S. Geological Survey Water-Resources Investigations Report 02-4005, 49 p.

Wong, M.F., and Young, S.T.M., 2001, Statistical summary of 

hydrologic and water-quality data from the Halawa, Haiku, 

and Kaneohe drainage basins before, during, and after H-3 

Highway construction, Oahu, Hawaii, 1983–99: U.S. Geological Survey Open-File Report 01-64, 69 p.

Wong, M.F., Nishimoto, D.C., Teeters, P.C., and Taogoshi, 

R.I., 2004, Water resources data, Hawaii and other Pacific 

areas, water year 2002: U.S. Geological Survey Water-Data 

Report HI-02-1, 390 p.

Yamane, C.M., and Lum, M.G., 1985, Quality of stormwater runoff, Mililani Town, Oahu, Hawaii, 1980–84, U.S. 

Geological Survey Water-Resources Investigations Report 

85-4265, 64 p.

Yim, S.K., and Dugan, G.L., 1975, Quality and quantity of 

nonpoint pollution sources in rural surface water runoff 

on Oahu, Hawaii: University of Hawaii Water Resources 

Research Center Technical Report no. 93, 60 p.

Young, S.T., and Ball, M.T., 2003, Rainfall, streamflow, and 

water-quality data during stormwater monitoring, Halawa 

Stream drainage basin, Oahu, Hawaii, July 1, 2002 to June 

30, 2003: U.S. Geological Survey Open-File Report 03-331, 

30 p.

Young, S.T.M., and Ball, M.T.J., 2004, Rainfall, streamflow, 

and water-quality data during stormwater monitoring, 

Halawa Stream drainage basin, Oahu, Hawaii, July 1, 2003 

to June 30, 2004: U.S. Geological Survey Open-File Report 

2004-1275, 22 p.

Young, S.T.M. and Ball, M.T.J., 2005, Rainfall, streamflow, 

and water-quality data during stormwater monitoring, 

Halawa Stream drainage basin, Oahu, Hawaii, July 1, 2004 

to June 30, 2005: U.S. Geological Survey Open-File Report 

2005-1280, 18 p.
Appendix A Table A1. Results of rinsate blank analyses for trace-element, nutrient, and other determinations for Storm Drain C. [<, less than value; E, estimated value; M, missing data; -, no analysis performed; values in bold exceed minimum reporting level; mS/cm at 25°C, microsiemens per centimeter 

milligrams per liter; N, nitrogen; CaCO3, calcium carbonate; mg/L, micrograms per liter] Property or constituent Units Sample Dates 17-Nov-99 25-Apr-00 3-Oct-00 02-Apr-01a 02-Apr-01b 21-Aug-01 12-Dec-01 26-Mar-02 13-Nov-02 19-J

Temperature, water degrees C - 18 - - - - - - - 

Specific conductance, field S/cm at 25°C - 2 - - - - - - - 

Specific conductance, lab S/cm at 25°C - - - 3 11 <3 <3 3 E4 E

pH, field standard units - 6.8 - - - - - - - 

pH, lab standard units - - - 7.4 6.4 7.7 7.2 7.4 8.1 

Total suspended solids mg/L - - - - - <10 <10 <10 <10 <1

Oil and grease mg/L - - - - - - - - - 

Nitrogen ammonia dissolved mg/L as N - <0.02 - <0.04 <0.04 <0.04 <0.04 <0.04 <0.04 <

Nitrogen, nitrite, dissolved mg/L as N - <0.01 - <0.006 <0.006 <0.006 <0.008 <0.008 <0.008 <

Nitrogen, ammonia + organic, total mg/L as N - <0.1 - E0.08 <0.08 <0.08 E0.07 0.1 E0.07 <

Nitrogen, nitrite + nitrate, dissolved mg/L as N - <0.05 - <0.05 <0.05 <0.05 <0.05 <0.05 <0.06 <

Total phosphorus mg/L - <0.05 - <0.06 <0.06 <0.06 <0.06 <0.06 <0.04 <

Phosphorus dissolved mg/L - <0.05 - <0.06 <0.06 <0.06 <0.06 <0.06 <0.04 <

Carbon, organic, total mg/L E0.2 1.4 - - - - - - - 

Hardness mg/L as CaCO3 M - - - - - - - - 

Calcium, dissolved mg/L 0.01 <0.002 0.009 - - - - - - 

Magnesium, dissolved mg/L 0.001 <0.001 <0.001 - - - - - - 

Sodium, dissolved mg/L 0.04 0.03 <0.03 - - - - - - 

Sodium adsorption ratio ratio 0.1 - - - - - - - - 

Silica, dissolved mg/L <0.02 <0.02 <0.02 - - - - - - 

Barium, dissolved mg/L <0.2 <0.2 <0.2 - - - - - - 

Beryllium, dissolved mg/L <0.2 <0.2 <0.2 - - - - - - Cadmium, dissolved mg/L <0.3 <0.3 <0.3 - - - - - - Total cadmium mg/L - - - <0.04 <0.04 <0.04 <0.04 <0.04 <0.04 <Chromium, dissolved mg/L <0.2 <0.2 <0.2 - - - - - - Total chromium mg/L - - - - - - - - - 

Cobalt, dissolved mg/L <0.2 <0.2 <0.2 - - - - - - 

Copper, dissolved mg/L <0.2 <0.2 <0.2 - - - - - - Total copper mg/L - - - <0.6 <0.6 <0.6 E0.4 <0.6 <0.6 <

Iron, dissolved mg/L <3 <3 5 - - - - - - 

Lead, dissolved mg/L 0.4 <0.3 <0.3 - - - - - - Total lead mg/L - - - <1 <1 <1 <1 <1 <0.06 <Manganese, dissolved mg/L 0.1 <0.1 <0.1 - - - - - - Molybdenum, dissolved mg/L <0.2 <0.2 <0.2 - - - - - - Nickel, dissolved mg/L <0.5 <0.5 <0.5 - - - - - - Total nickel mg/L - - - - - - - - - 

Silver, dissolved mg/L <0.2 <0.2 <0.2 - - - - - - 

Strontium, dissolved mg/L <0.1 <0.1 <0.1 - - - - - - Zinc, dissolved mg/L 3.2 <0.5 <0.5 - - - - - - Total zinc mg/L - - - 8 3 14 8 21 6 Aluminum, dissolved mg/L 0.3 0.4 0.3 - - - - - - 

Total dissolved solids mg/L - - - - - <10 <10 <10 <10 <1

a Automatic sampler before cleaning.b Automatic sampler after cleaning.
Appendix A 49

Table A2. Results of rinsate blank analyses for semivolatilecompound determinations for Storm Drain C.

[Concentrations are reported as micrograms per liter; <, less than]

Property or constituent Sample Date

11/17/1999

Acenaphthylene <2

Acenaphthene <2

Anthracene <2

Benzo[b]fluoranthene <3

Benzo[k]fluoranthene <3

Benzo[a]pyrene <3

2-Chloroethylether <2

2-Chloroethoxymethane <3

Chloroisopropylether <2

Butylbenzylphthalate <4

Chrysene <3

Diethyl phthalate <2

Dimethyl phthalate <2

Fluoranthene <2

9H-Fluorene <2

Hexachlorocyclopentadiene <2

Hexachloroethane <2

Indenopyrene <3

Isophorone <2

Nitrosodipropylamine <2

Nitrosodiphenylamine <3

Nitrosodimethylamine <3

Nitrobenzene <2

Phenanthrene <2

Pyrene <2

Benzo[g,h,i]perylene <3

Benzo[a]anthracene <2

1,2-Dichlorobenzene <2

1,2,4-Trichlorobenzene <2

Dibenzo[a,h]anthracene <3

1,3-Dichlorobenzene <2

1,4-Dichlorobenzene <2

2-Chloronaphthalene <2

Di-n-octyl phthalate <5

2,4-Dinitrotoluene <3

2,6-Dinitrotoluene <2

4-Bromophenyl phenyl ether <2

4-Chlorophenyl phenyl ether <2

Naphthalene <2

2-Ethylhexyl phthalate <5

Dibutyl phthalate <3

Hexachlorobenzene <2

Hexachlorobutadiene <3
Table A3. Results of rinsate blank analyses for trace-element, nutrient, and other determinations for Xeriscape Garden. [<, less than; E, estimated; M, missing data; –, no analysis performed; values in bold exceed minimum reporting level; mS/cm at 25°C, microsiemens per centimeter at 25 degree

calcium carbonate; mg/L, milligrams per liter; mg/L, micrograms per liter] Property or constituent Units Sample Date 25-Nov-98 17-Nov-99 3-May-00 3-Oct-00 21-Aug-01a 21-Aug-01b 21-Aug-01c 12-Dec-01 27-Mar-02 13-Nov-02 18

Temperature, water degrees C - - 25.5 - - - - - - - 

Specific conductance, field S/cm at 25°C - - 2 - - - - - - - 

Specific conductance, lab S/cm at 25°C - - - - 3 <3 <3 3 3 E4 

pH, field standard units - - 6.4 - - - - - - - 

pH, lab standard units - - - - 7.5 7.5 7.6 7.4 7.6 8.3 

Total suspended solids mg/L - - - - <10 - - <10 <10 <10 

Nitrogen ammonia dissolved mg/L as N - - <0.02 - E0.03 <0.04 <0.04 <0.04 <0.04 <0.04 

Nitrogen, nitrite, dissolved mg/L as N - - <0.01 - <0.006 <0.006 <0.006 <0.008 <0.008 <0.008 

Nitrogen, ammonia + organic, total mg/L as N - - <0.1 - <0.08 <0.08 <0.08 <0.1 E0.06 E0.08 

Nitrogen, nitrite + nitrate, dissolved mg/L as N - - <0.05 - <0.05 <0.05 <0.05 <0.05 <0.05 <0.06 

Total phosphorus mg/L - - <0.05 - <0.06 <0.06 <0.06 <0.06 <0.06 <0.04 

Phosphorus dissolved mg/L - - <0.05 - <0.06 <0.06 <0.06 <0.06 <0.06 <0.04 

Carbon, organic, total mg/L - 0.9 E0.1 - - - - - - - 

Hardness mg/L as CaCO3 - M M - - - - - - - 

Calcium, dissolved mg/L 0.006 0.01 0.014 0.01 - - - - - - 

Magnesium, dissolved mg/L <0.001 0.001 0.002 <0.001 - - - - - - 

Sodium, dissolved mg/L <0.03 <0.03 <0.03 <0.03 - - - - - - 

Silica, dissolved mg/L <0.02 <0.02 <0.02 <0.02 - - - - - - 

Barium, dissolved mg/L <0.2 <0.2 <0.2 <0.2 - - - - - - 

Beryllium, dissolved mg/L <0.2 <0.2 <0.2 <0.2 - - - - - - 

Cadmium, dissolved mg/L <0.3 <0.3 <0.3 <0.3 - - - - - - 

Total cadmium mg/L - - - - <0.04 <0.04 <0.04 <0.04 <0.04 <0.04 

Chromium, dissolved mg/L <0.2 <0.2 <0.2 <0.2 - - - - - - 

Cobalt, dissolved mg/L <0.2 <0.2 <0.2 <0.2 - - - - - - 

Copper, dissolved mg/L <0.2 <0.2 <0.2 <0.2 - - - - - - 

Total copper mg/L - - - - <0.6 <0.6 <0.6 <0.6 <0.6 <0.6 

Iron, dissolved mg/L <3 <3 <3 <3 - - - - - - 

Lead, dissolved mg/L <0.3 <0.3 <0.3 <0.3 - - - - - - 

Total lead mg/L - - - - <1 <1 <1 <1 <1 <0.06 

Manganese, dissolved mg/L <0.1 <0.1 0.1 <0.1 - - - - - - 

Molybdenum, dissolved mg/L <0.2 <0.2 <0.2 <0.2 - - - - - - 

Nickel, dissolved mg/L <0.5 <0.5 <0.5 <0.5 - - - - - - 

Silver, dissolved mg/L <0.2 <0.2 <0.2 <0.2 - - - - - - 

Strontium, dissolved mg/L <0.1 0.3 <0.1 <0.1 - - - - - - 

Zinc, dissolved mg/L <0.5 <0.5 <0.5 <0.5 - - - - - - 

Total zinc mg/L - - - - 13 <1 <1 13 7 2 

Aluminum, dissolved mg/L <0.3 <0.3 <0.3 0.3 - - - - - - 

Total dissolved solids mg/L - - - - <10 <10 <10 <10 

a Automatic sampler after cleaning.b Teflon bag.c Isokinetic sampler.
Appendix A 51

Table A4. Results of rinsate blank analyses for semivolatilecompound determinations for Xeriscape Garden.

[Concentrations are reported as micrograms per liter; <, less than]

Property or constituent Sample Dates

17-Nov-99 3-May-00

Acenaphthylene <2 <2

Acenaphthene <2 <2

Anthracene <2 <2

Benzo[b]fluoranthene <3 <3

Benzo[k]fluoranthene <3 <3

Benzo[a]pyrene <3 <3

2-Chloroethylether <2 <2

2-Chloroethoxymethane <3 <3

Chloroisopropylether <2 <2

Butylbenzylphthalate <4 <4

Chrysene <3 <3

Diethyl phthalate <2 <2

Dimethyl phthalate <2 <2

Fluoranthene <2 <2

9H-Fluorene <2 <2

Hexachlorocyclopentadiene <2 <2

Hexachloroethane <2 <2

Indenopyrene <3 <3

Isophorone <2 <2

Nitrosodipropylamine <2 <2

Nitrosodiphenylamine <3 <3

Nitrosodimethylamine <3 <3

Nitrobenzene <2 <2

Phenanthrene <2 <2

Pyrene <2 <2

Benzo[g,h,i]perylene <3 <3

Benzo[a]anthracene <2 <2

1,2-Dichlorobenzene <2 <2

1,2,4-Trichlorobenzene <2 <2

Dibenzo[a,h]anthracene <3 <3

1,3-Dichlorobenzene <2 <2

1,4-Dichlorobenzene <2 <2

2-Chloronaphthalene <2 <2

Di-n-octyl phthalate <5 <5

2,4-Dinitrotoluene <3 <3

2,6-Dinitrotoluene <2 <2

4-Bromophenyl phenyl ether <2 <2

4-Chlorophenyl phenyl ether <2 <2

Naphthalene <2 <2

2-Ethylhexyl phthalate <5 <5

Dibutyl phthalate <3 <3

Hexachlorobenzene <2 <2

Hexachlorobutadiene <3 <3
Table A5. Results of rinsate blank analyses for trace-element, nutrient, and other determinations for Quarantine Station. [<, less than; E, estimated; –, no analysis performed; values in bold exceed minimum reporting level; mS/cm at 25°C, microsiemens per centimeter at 25 degrees Celsius; N, nitrmg/L, micrograms per liter] Property or constituent Units Sample Date 7-Jan-02 27-Mar-02 27-Feb-03a 27-Feb-03b 27-Feb-

Chemical oxygen demand mg/L - - - <10 <10 

Specific conductance, lab S/cm at 25°C <3 4 144 - - 

pH, lab standard units 7.4 7.7 3.5 - - 

Total suspended solids mg/L <10 <10 <10 - - 

Oil and grease mg/L - - - <7 <7 Nitrogen ammonia dissolved mg/L as N E0.02 E0.04 <0.04 - - 

Nitrogen, nitrite, dissolved mg/L as N <0.008 <0.008 <0.008 - - 

Nitrogen, ammonia + organic, total mg/L as N E0.07 E0.08 <0.1 - - 

Nitrogen, nitrite + nitrate, dissolved mg/L as N <0.05 <0.05 <0.06 - - 

Total phosphorus mg/L <0.06 <0.06 <0.04 - - 

Phosphorus dissolved mg/L <0.06 <0.06 <0.04 - - 

Total cadmium mg/L <0.04 <0.04 <0.04 - - 

Total chromium mg/L - - - - - 

Total copper mg/L <0.6 <0.6 <0.6 - - 

Total lead mg/L <1 <1 <0.06 - - 

Total nickel mg/L - - - - - 

Total zinc mg/L 3 11 <2 - - 

Total petroleum hydrocarbons mg/L - - - <2 <2 

Total dissolved solids mg/L <10 <10 <10 - - 

a Automatic sampler after cleaning. b Teflon bag. c Low Density Polyethylene (LDPE) bag.
Appendix B

0123

DAILY RAINFALL,

IN INCHES

0

103050

70

Oct Nov Dec Jan Feb Mar Apr May Jun Jul 

0

0.5

1

1.5

2

2.5

DAILY MEAN DISCHARGE,

 IN CUBIC FEET PER SECOND

1998 1999

Figure B1. Daily values for discharge at Storm Drain C and Xeriscape Garden and rainfall at Tunnel rain gage from October 1998 to Selines represent days that samples were collected.
0 0.5 1.5 2.5 3.5

DAILY MEAN DISCHARGE,

 IN CUBIC FEET PER SECOND

0

60

120180

05

152535

DAILY RAINFALL,

IN INCHES

1999 2000

Oct Nov Dec Jan Feb Mar Apr May Jun Jul 

Figure B2. Daily values for discharge at Storm Drain C and Xeriscape Garden and rainfall at Tunnel rain gage from October 1999 to Selines represent days that samples were collected.
Figure B3. Daily values for discharge at Storm Drain C and Xeriscape Garden and rainfall at Tunnel rain gage from October 2000 to Serepresent days that samples were collected.

0

0.51.52.53.54.5

0

0.5

1

1.5

2

2.5

0

10305070

DAILY MEAN DISCHARGE,

 IN CUBIC FEET PER SECOND

DAILY RAINFALL,

IN INCHES

2000 2001

TU

Oct Nov Dec Jan Feb Mar Apr May Jun Jul 
050 100 150 200 2500123404812

DAILY MEAN DISCHARGE,

 IN CUBIC FEET PER SECOND

2001 2002

Oct Nov Dec Jan Feb Mar Apr May Jun Jul 

DAILY RAINFALL,

IN INCHES

Figure B4. Daily values for discharge at Storm Drain C and Xeriscape Garden and rainfall at Tunnel rain gage from October 2001 to Selines represent days that samples were collected.
0

4080

120160

0

0.5

1

1.5

2

2.5

02468

DAILY MEAN DISCHARGE,

 IN CUBIC FEET PER SECOND

2002 2003

Oct Nov Dec Jan Feb Mar Apr May Jun Jul 

DAILY RAINFALL,

IN INCHES

Figure B5. Daily values for discharge at Storm Drain C and Xeriscape Garden and rainfall at Tunnel rain gage from October 2002 to Selines represent days that samples were collected.
Figure B6. Daily values for discharge at Storm Drain C and Xeriscape Garden and rainfall at Tunnel rain gage from October 2003 to Serepresent days that samples were collected.

0

50

100150200250

0.02.04.06.08.0

048

1216

DAILY MEAN DISCHARGE,

 IN CUBIC FEET PER SECOND

2003 2004

Oct Nov Dec Jan Feb Mar Apr May Jun Jul 

DAILY RAINFALL,

IN INCHES
Appendix CTable C1. Statistical summary of detections and values for selected physical properties and constituents measured in grab samples collected at Bri[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property; mS/cm at 25°C, microsiemens per centimeter at 25 degrees Celsius; mg/L, m

gram per liter; –, no data or not computed; E, estimated value; N, nitrogen; NO2, nitrite; cfs, cubic feet per second]

USGS parameter code Property or constituent Units

Grab Samples

Number Of 

Samples Non-Detects Detects Min. 

00010 Temperature, water degrees Celsius 11 – 11 17.9 

00061 Discharge, instantaneous cfs 11 – 11 30 

00065 Gage height feet 9 – 9 96.52 

00095 Specific conductance, field mS/cm at 25°C 9 – 9 59 

90095 Specific conductance, lab mS/cm at 25°C 11 – 11 E68 00340 Chemical oxygen demand mg/L 11 2 9 10 

00400 pH, field standard units 9 – 9 5.8 

00403 pH, lab standard units 11 – 11 6.9 

00530 Total suspended solids mg/L 11 2 9 32 

00556 Oil and grease mg/L 11 11 – – 

00600 Total nitrogen mg/L 11 – 11 0.25 

00608 Nitrogen, ammonia, dissolved mg/L as N 11 11 – – 

00613 Nitrogen, nitrite, dissolved mg/L as N 11 9 2 E0.00

71856 Nitrite, dissolved mg/L as NO2 1 – 1 – 

00625 Nitrogen, ammonia + organic, total mg/L as N 11 – 11 0.2 

00631 Nitrogen, nitrite + nitrate, dissolved mg/L as N 11 1 10 0.05 

00665 Total phosphorus mg/L 11 – 11 E0.03 

00666 Phosphorus, dissolved mg/L 11 10 1 – 

01027 Total cadmium mg/L 11 5 6 E0.02 

01042 Total copper mg/L 11 – 11 2 

01051 Total lead mg/L 11 4 7 0.07 01092 Total zinc mg/L 11 – 11 2 45501 Total petroleum hydrocarbons mg/L 11 9 2 2 

70300 Total dissolved solids mg/L 11 – 11 42 
60 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

Table C2. Statistical summary of detections and values for selected physical properties and constituents measured in grab samples 

collected at Storm Drain C.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property; mS/cm at 25°C, microsiemens per centimeter at 25 degrees 

Celsius; mg/L, milligram per liter; mg/L, microgram per liter; –, no data or not computed; na, not applicable; E, estimated value; %, percent; N, nitrogen; NO2, 

nitrite; NO3, nitrate; NH4, ammonia; CaCO3, calcium carbonate; mm of Hg, millimeters of mercury; NTU, nephelometric turbidity unit; cfs, cubic feet per 

second]

USGS

parameter 

code

Property or constituent Units

Grab Samples

Number Of Detected Values

Samples Non-Detects Detects Min. Median Max.

00010 Temperature, water degrees Celsius 15 – 15 18 22 24

00020 Temperature, air degrees Celsius 6 – 6 21 21.75 24

00025 Air pressure mm of Hg 5 – 5 751 756 761

00060 Discharge cfs 1 – 1 – 6.6 –

00061 Discharge, instantaneous cfs 45 – 45 0.01 3 24

00065 Gage height feet 45 – 45 1.22 1.7 3.63

00076 Turbidity NTU 20 – 20 1.3 3.75 22

00095 Specific conductance, field mS/cm at 25°C 18 – 18 25 91 314

90095 Specific conductance, lab mS/cm at 25°C 29 – 29 28 68 327

00300 Oxygen dissolved mg/L 3 – 3 8.1 8.3 10.5

00301 Oxygen dissolved % of saturation 3 – 3 96 97 121

00340 Chemical oxygen demand mg/L 18 6 12 10 30 60

00400 pH, field standard units 19 – 19 6 7.4 8

00403 pH, lab standard units 29 – 29 6.8 7.6 8.2

00405 Carbon dioxide mg/L 1 – 1 – 1.6 –

00530 Total suspended solids mg/L 38 10 28 1 43 560

00556 Oil and grease mg/L 16 8 8 1 4.5 8

00600 Total nitrogen mg/L 20 – 20 0.16 0.425 1.6

00605 Organic nitrogen mg/L 2 – 2 0.19 – 0.55

00608 Nitrogen ammonia dissolved mg/L as N 20 14 6 0.02 0.035 0.06

00613 Nitrogen, nitrite, dissolved mg/L as N 18 8 10 E0.004 0.009 0.035

00618 Nitrogen, nitrate, dissolved mg/L as N 5 – 5 0.07 0.09 0.15

00625 Nitrogen, total organic + ammonia mg/L as N 20 – 20 0.12 0.235 1.5

00631 Nitrogen, nitrite + nitrate dissolved mg/L as N 20 2 18 E0.03 0.115 0.58

71846 Ammonia, dissolved mg/L as NH4 2 – 2 0.05 0.08

71851 Nitrate, dissolved mg/L as NO3 5 – 5 0.288 0.416 0.677

71856 Nitrite, dissolved mg/L as NO2 5 – 5 0.033 0.046 0.115

00665 Total phosphorus mg/L 20 1 19 E0.03 0.07 0.24

00666 Phosphorus dissolved mg/L 18 13 5 E0.02 0.03 0.08

00680 Carbon, organic, total mg/L 4 – 4 7.5 8.4 9.9

00900 Hardness mg/L as CaCO3 1 – 1 – 35 35

00915 Calcium, dissolved mg/L 1 – 1 – 12.2 –

00925 Magnesium, dissolved mg/L 1 – 1 – 0.934 –

00930 Sodium, dissolved mg/L 1 – 1 – 8.93 –

00931 Sodium adsorption ratio ratio 1 – 1 – 0.7 –

00932 Sodium, equivalents of major cations percent 1 – 1 – 35 –

00935 Potassium, dissolved mg/L 1 – 1 – 1.05 –

00940 Chloride, dissolved mg/L 6 – 6 1.69 4.55 9.22

00945 Sulfate, dissolved mg/L 6 – 6 1.3 3.65 6.2

00950 Fluoride, dissolved mg/L 1 1 – – – –

00955 Silica, dissolved mg/L 1 – 1 – 4.21 –

01005 Barium, dissolved mg/L 1 – 1 – 7.6 –

01027 Total cadmium mg/L 23 1 22 0.02 0.1 0.61

01030 Chromium, dissolved mg/L 6 – 6 2 2.9 4.7

01034 Total chromium mg/L 5 – 5 5 6 9.8

01035 Cobalt, dissolved mg/L 1 1 – – – –

01040 Copper, dissolved mg/L 6 – 6 1.5 3.05 8.6

01042 Total copper mg/L 28 – 28 1.9 11.7 68

01045 Total iron mg/L 1 – 1 – 1130 –

01046 Iron, dissolved mg/L 1 – 1 – E8 –

01049 Lead, dissolved mg/L 6 6 – – – –

01051 Total lead mg/L 28 3 25 0.49 4.37 20.2

01056 Manganese, dissolved mg/L 1 1 – – – –

01060 Molybdenum, dissolved mg/L 1 1 – – – –

01065 Nickel, dissolved mg/L 6 6 – – – –

01067 Total nickel mg/L 5 – 5 2.4 4.1 8.2

01075 Silver, dissolved mg/L 1 1 – – – –

01080 Strontium, dissolved mg/L 1 – 1 – 72.4 –

01085 Vanadium, dissolved mg/L 1 1 – – – –

01090 Zinc, dissolved mg/L 6 2 4 E11 18 39

01092 Total zinc mg/L 28 – 28 8 57.5 274

01105 Total aluminum mg/L 1 – 1 – 930 –

01106 Aluminum, dissolved mg/L 1 – 1 – 90 –

01130 Lithium, dissolved mg/L 1 1 – – – –

01145 Selenium, dissolved mg/L 1 1 – – – –

45501 Total petroleum hydrocarbons mg/L 12 9 3 2 3 3

70300 Total dissolved solids mg/L 16 – 16 15 48 192

70301 Residue, sum of constituents mg/L 1 – 1 – 56 –

70302 Residue tons/day 1 – 1 – 0.05 –

70303 Residue tons/acre-feet 1 – 1 – 0.09 –

90410 Acid neutralizing capacity mg/L as CaCO3 1 – 1 – 34 –
Appendix C 61

Table C3. Statistical summary of detections and values for selected physical properties and constituents measured in composite 

samples collected at Storm Drain C.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property; mS/cm at 25°C, microsiemens per centimeter at 25 degrees 

Celsius; mg/L, milligram per liter; mg/L, microgram per liter; –, no data or not computed; NTU, nephelometric turbidity unit; E, estimated value; N, nitrogen; 

NO2, nitrite; NO3, nitrate; NH4, ammonia; CaCO3, calcium carbonate; mm of Hg, millimeters of mercury; cfs, cubic feet per second]

USGS

parameter 

code

Property or constituent Units

Composite Samples

Number Of Detected Values

Samples Non-Detects Detects Min. Median Max.

00010 Temperature, water degrees Celsius 1 – 1 – 17.2 –

00025 Air pressure mm of Hg 3 – 3 756 756 757

00060 Discharge cfs 14 – 14 6.5 11 20

00061 Discharge, instantaneous cfs 13 – 13 0.3 4.7 18

00065 Gage height feet 12 – 12 1.3 1.845 2.37

00076 Turbidity NTU 10 – 10 1.4 4.1 14

00095 Specific conductance, field mS/cm at 25°C 8 – 8 37 45 65

90095 Specific conductance, lab mS/cm at 25°C 24 – 24 36 52.5 114

00300 Oxygen dissolved mg/L 1 – 1 – 8.3 –

00340 Chemical oxygen demand mg/L 20 5 15 10 30 80

00400 pH, field standard units 7 – 7 6.6 7.3 8

00403 pH, lab standard units 24 – 24 7 7.5 8.1

00530 Total suspended solids mg/L 28 4 24 13 48 103

00556 Oil and grease mg/L 6 1 5 2 3 E5

00600 Total nitrogen mg/L 19 – 19 0.075 0.295 1.46

00605 Organic nitrogen mg/L 5 – 5 0.25 0.63 1.4

00608 Nitrogen ammonia dissolved mg/L as N 19 9 10 0.02 0.03 0.05

00613 Nitrogen, nitrite, dissolved mg/L as N 17 13 4 E0.004 0.011 0.024

00618 Nitrogen, nitrate, dissolved mg/L as N 2 – 2 0.05 0.085 0.12

00625 Nitrogen, total organic + ammonia mg/L as N 20 1 19 E0.09 0.35 1.4

00631 Nitrogen, nitrite + nitrate dissolved mg/L as N 19 8 11 E0.03 0.05 0.13

71846 Ammonia, dissolved mg/L as NH4 5 – 5 0.03 0.05 0.07

71851 Nitrate, dissolved mg/L as NO3 2 – 2 0.23 – 0.522

71856 Nitrite, dissolved mg/L as NO2 3 – 3 0.026 0.046 0.079

00665 Total phosphorus mg/L 20 2 18 E0.02 0.09 0.38

00666 Phosphorus dissolved mg/L 17 15 2 E0.03 0.03 0.03

00680 Carbon, organic, total mg/L 6 – 6 5.6 6.7 11

00900 Hardness mg/L as CaCO3 1 – 1 – 36 –

00915 Calcium, dissolved mg/L 1 – 1 – 12.8 –

00925 Magnesium, dissolved mg/L 1 – 1 – 0.963 –

00930 Sodium, dissolved mg/L 1 – 1 – 7.43 –

00931 Sodium adsorption ratio ratio 1 – 1 – 0.5 –

00932 Sodium, equivalents of major cations percent 1 – 1 – 30 –

00935 Potassium, dissolved mg/L 1 – 1 – 1.02 –

00940 Chloride, dissolved mg/L 7 – 7 0.71 3 10.2

00945 Sulfate, dissolved mg/L 7 – 7 0.9 1.3 41.8

00950 Fluoride, dissolved mg/L 1 1 – – – –

00955 Silica, dissolved mg/L 1 – 1 – 4.85 –

01005 Barium, dissolved ug/L 1 – 1 – 8.1 –

01027 Total cadmium mg/L 16 – 16 E0.02 0.165 0.53

01030 Chromium, dissolved mg/L 8 – 8 E0.7 2.85 3.6

01034 Total chromium mg/L 8 – 8 5 10.55 16.5

01035 Cobalt, dissolved mg/L 1 1 – – – –

01040 Copper, dissolved mg/L 8 – 8 1.9 2.4 5.4

01042 Total copper mg/L 24 – 24 1.4 26.3 136

01045 Total iron mg/L 1 – 1 – 1510 –

01046 Iron, dissolved mg/L 1 – 1 – 21 –

01049 Lead, dissolved mg/L 8 8 – – – –

01051 Total lead mg/L 24 1 23 0.92 9.5 44.4

01056 Manganese, dissolved mg/L 1 1 – – – –

01060 Molybdenum, dissolved mg/L 1 1 – – – –

01065 Nickel, dissolved mg/L 8 6 2 E0.7 – 0.9

01067 Total nickel mg/L 8 – 8 4.6 8.95 20.8

01075 Silver, dissolved mg/L 1 1 – – – –

01080 Strontium, dissolved mg/L 1 – 1 – 78.3 –

01085 Vanadium, dissolved mg/L 1 1 – – – –

01090 Zinc, dissolved mg/L 8 4 4 6.5 17 21

01092 Total zinc mg/L 24 – 24 12 105.5 290

01105 Total aluminum mg/L 1 – 1 – 1220 –

01106 Aluminum, dissolved mg/L 1 – 1 – 80 –

01130 Lithium, dissolved mg/L 1 1 – – – –

01145 Selenium, dissolved mg/L 1 1 – – – –

45501 Total petroleum hydrocarbons mg/L 2 – 2 3 – 4

70300 Total dissolved solids mg/L 17 – 17 16 23 69

70301 Residue, sum of constituents mg/L 1 – 1 – 102 –

70302 Residue tons/day 1 – 1 – 0.06 –

70303 Residue tons/acre-feet 1 – 1 – 0.09 –

90410 Acid neutralizing capacity mg/L as CaCO3 1 – 1 – 37 –
62 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

Table C4. Statistical summary of detections and values for selected physical properties and constituents measured in grab samples 

collected at Xeriscape Garden.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property; mS/cm at 25°C, microsiemens per centimeter at 25 degrees 

Celsius; mg/L, milligram per liter; mg/L, microgram per liter; –, no data or not computed; %, percent; NTU, nephelometric turbidity unit; E, estimated value; N, 

nitrogen; NH4, ammonia; CaCO3, calcium carbonate; mm of Hg, millimeters of mercury; cfs, cubic feet per second]

USGS

parameter 

code

Property or constituent Units

Grab Samples

Number Of Detected Values

Samples Non-Detects Detects Min. Median Max.

00010 Temperature, water degrees Celsius 18 – 18 18.3 21.5 25.5

00020 Temperature, air degrees Celsius 7 – 7 20 22.5 28.5

00025 Air pressure mm of Hg 7 – 7 757 761 764

00061 Discharge, instantaneous cfs 33 – 33 0.03 35 640

00065 Gage height feet 32 – 32 5.89 7.195 10.1

00076 Turbidity NTU 16 – 16 0.58 32 380

00095 Specific conductance, field mS/cm at 25°C 19 – 19 57 107 359

90095 Specific conductance, lab mS/cm at 25°C 23 – 23 61 118 352

00300 Oxygen dissolved mg/L 6 – 6 5.9 8.55 9.4

00301 Oxygen dissolved % of saturation 6 – 6 73 96 101

00340 Chemical oxygen demand mg/L 21 8 13 10 20 200

00400 pH, field standard units 19 – 19 6.7 7.1 8.3

00403 pH, lab standard units 23 – 23 6.9 7.5 8.1

00405 Carbon dioxide mg/L 2 – 2 6.9 – 9.3

00530 Total suspended solids mg/L 32 6 26 3 79 1930

00556 Oil and grease mg/L 23 21 2 2 – E4

00600 Total nitrogen mg/L 21 – 21 0.075 0.44 6.7

00605 Organic nitrogen mg/L 1 – 1 – 0.08 –

00608 Nitrogen ammonia dissolved mg/L as N 22 21 1 – 0.03 –

00613 Nitrogen, nitrite, dissolved mg/L as N 18 16 2 0.003 – E0.004

00625 Nitrogen, total organic + ammonia mg/L as N 22 – 22 E0.05 0.3 6.6

00631 Nitrogen, nitrite + nitrate dissolved mg/L as N 22 6 16 0.05 0.11 0.35

71846 Ammonia, dissolved mg/L as NH4 1 – 1 – 0.03 –

00665 Total phosphorus mg/L 22 6 16 E0.03 0.1 2.31

00666 Phosphorus dissolved mg/L 18 14 4 E0.02 0.025 E0.04

00680 Carbon, organic, total mg/L 8 – 8 1.4 2.8 13.9

00900 Hardness mS/cm at 25°C 2 – 2 27 – 39

00915 Calcium, dissolved mg/L 2 – 2 5.72 – 7.69

00925 Magnesium, dissolved mg/L 2 – 2 3.04 – 4.86

00930 Sodium, dissolved mg/L 2 – 2 8.42 – 11

00931 Sodium adsorption ratio ratio 2 – 2 0.7 – 0.8

00932 Sodium, equivalents of major cations percent 2 – 2 37 – 39

00935 Potassium, dissolved mg/L 2 – 2 1 – 1.71

00940 Chloride, dissolved mg/L 7 – 7 11.2 16.3 39.5

00945 Sulfate, dissolved mg/L 7 – 7 3 4.3 9.8

00950 Fluoride, dissolved mg/L 2 2 – – – –

00955 Silica, dissolved mg/L 2 – 2 7.53 – 12.8

01005 Barium, dissolved mg/L 2 – 2 E1 – 1.3

01027 Total cadmium mg/L 15 7 8 E0.02 0.085 0.41

01030 Chromium, dissolved mg/L 8 5 3 E0.5 0.8 2.1

01034 Total chromium mg/L 6 3 3 1 2.6 6

01035 Cobalt, dissolved mg/L 2 2 – – – –

01040 Copper, dissolved mg/L 8 2 6 1 1.35 2

01042 Total copper mg/L 21 1 20 1 3.85 114

01045 Total iron mg/L 2 – 2 410 – 1810

01046 Iron, dissolved mg/L 2 – 2 29 – 142

01049 Lead, dissolved mg/L 8 8 – – – –

01051 Total lead mg/L 21 7 14 0.09 0.85 8.64

01056 Manganese, dissolved mg/L 2 – 2 3.5 – 7.3

01060 Molybdenum, dissolved mg/L 2 2 – – – –

01065 Nickel, dissolved mg/L 8 8 – – – –

01067 Total nickel mg/L 6 3 3 1.1 1.31 5

01075 Silver, dissolved mg/L 2 2 – – – –

01080 Strontium, dissolved mg/L 2 – 2 35.1 – 45.6

01085 Vanadium, dissolved mg/L 2 2 – – – –

01090 Zinc, dissolved mg/L 8 7 1 – E10 –

01092 Total zinc mg/L 21 6 15 1 9 146

01105 Total aluminum mg/L 2 – 2 530 – 2020

01106 Aluminum, dissolved mg/L 2 – 2 20 – 180

01130 Lithium, dissolved mg/L 2 2 – – – –

01145 Selenium, dissolved mg/L 2 2 – – – –

45501 Total petroleum hydrocarbons mg/L 14 14 – – – –

70300 Total dissolved solids mg/L 17 – 17 36 72 110

70301 Residue, sum of constituents mg/L 2 – 2 60 – 82

70302 Residue tons/day 2 – 2 4.32 – 5.29

70303 Residue tons/acre-feet 2 – 2 0.09 – 0.12

90410 Acid neutralizing capacity mg/L as CaCO3 2 – 2 24 – 36
Appendix C 63

Table C5. Statistical summary of detections and values for selected physical properties and constituents measured in composite 

samples collected at Xeriscape Garden.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property; mS/cm at 25°C, microsiemens per centimeter at 25 degrees 

Celsius; mg/L, milligram per liter; mg/L, microgram per liter; –, no data or not computed; NTU, nephelometric turbidity unit; E, estimated value; N, nitrogen; 

cfs, cubic feet per second]

USGS

parameter 

code

Property or constituent Units

Composite Samples

Number Of Detected Values

Samples Non-Detects Detects Min. Median Max.

00010 Temperature, water degrees Celsius 2 – 2 20.3 – 21.2

00060 Discharge cfs 15 – 15 41 82 641

00061 Discharge, instantaneous cfs 19 – 19 28 39 131

00065 Gage height feet 19 – 19 7.04 7.28 8.2

00076 Turbidity NTU 15 – 15 15 27 390

00095 Specific conductance, field mS/cm at 25°C 5 – 5 43 61 128

90095 Specific conductance, lab mS/cm at 25°C 25 – 25 50 85 145

00340 Chemical oxygen demand mg/L 17 – 17 10 90 410

00400 pH, field standard units 6 – 6 6.3 7.15 7.6

00403 pH, lab standard units 25 – 25 6.6 7.3 7.8

00530 Total suspended solids mg/L 34 1 33 9 165 2420

00556 Oil and grease mg/L 5 4 1 – 1 –

00600 Total nitrogen mg/L 16 – 16 0.565 2.45 14

00608 Nitrogen ammonia dissolved mg/L as N 16 15 1 – 0.03 –

00613 Nitrogen, nitrite, dissolved mg/L as N 16 15 1 – E0.004 –

00625 Nitrogen, total organic + ammonia mg/L as N 16 – 16 0.54 2.3 14

00631 Nitrogen, nitrite + nitrate dissolved mg/L as N 16 3 13 0.05 0.09 0.29

00665 Total phosphorus mg/L 16 – 16 0.07 0.575 3.51

00666 Phosphorus dissolved mg/L 16 13 3 E0.02 E0.02 E0.03

00680 Carbon, organic, total mg/L 5 – 5 16.2 24.7 27.1

00940 Chloride, dissolved mg/L 9 – 9 6.75 9.25 15.7

00945 Sulfate, dissolved mg/L 9 – 9 2.3 2.8 3.2

01027 Total cadmium mg/L 16 2 14 0.06 0.155 0.51

01030 Chromium, dissolved mg/L 9 – 9 0.9 1.4 1.7

01034 Total chromium mg/L 9 – 9 4.2 8.1 36.8

01040 Copper, dissolved mg/L 9 – 9 1.6 2.1 3.2

01042 Total copper mg/L 25 – 25 1.7 20.5 137

01049 Lead, dissolved mg/L 9 9 – – – –

01051 Total lead mg/L 25 3 22 1.3 4.73 14.3

01065 Nickel, dissolved mg/L 9 9 – – – –

01067 Total nickel mg/L 9 – 9 2.06 6.1 20.5

01090 Zinc, dissolved mg/L 9 5 4 1.7 3.15 10.5

01092 Total zinc mg/L 25 1 24 8 58.5 191

70300 Total dissolved solids mg/L 15 – 15 32 51 82
64 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

Table C6. Statistical summary of detections and values for selected physical properties and constituents measured in grab samples 

collected at Quarantine Station.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property; mS/cm at 25°C, microsiemens per centimeter at 25 degrees 

Celsius; mg/L, milligram per liter; mg/L, microgram per liter; –, no data or not computed; E, estimated value; N, nitrogen; NH4, ammonia]

USGS

parameter 

code

Property or constituent Units

Grab Samples

Number Of Detected Values

Samples Non-Detects Detects Min. Median Max.

00010 Temperature, water degrees Celsius 11 – 11 18.3 21.8 24

00061 Discharge, instantaneous cfs 15 – 15 0.78 50 289

00065 Gage height feet 13 – 13 3.43 4.92 6.56

00095 Specific conductance, field mS/cm at 25°C 11 – 11 68 102 173

90095 Specific conductance, lab mS/cm at 25°C 14 – 14 E70 111 163

00340 Chemical oxygen demand mg/L 11 2 9 10 20 130

00400 pH, field standard units 11 – 11 6.5 7.4 8.3

00403 pH, lab standard units 14 – 14 6.7 7.5 7.8

00530 Total suspended solids mg/L 12 2 10 11 100 769

00556 Oil and grease mg/L 13 11 2 3 – 6

00600 Total nitrogen mg/L 11 – 11 0.27 0.7 4.3

00605 Organic nitrogen mg/L 1 – 1 – 1.5 –

00608 Nitrogen ammonia dissolved mg/L as N 11 10 1 – 0.08 –

00613 Nitrogen, nitrite, dissolved mg/L as N 11 7 4 E0.004 E0.005 E0.007

00625 Nitrogen, total organic + ammonia mg/L as N 11 – 11 0.23 0.51 4.1

00631 Nitrogen, nitrite + nitrate dissolved mg/L as N 11 1 10 E0.04 0.165 0.26

00665 Total phosphorus mg/L 11 – 11 E0.04 0.15 2.06

00666 Phosphorus dissolved mg/L 11 7 4 E0.02 0.025 0.12

71846 Ammonia, dissolved mg/L as NH4 1 – 1 – 0.1 –

01027 Total cadmium mg/L 14 3 11 E0.03 0.07 0.38

01042 Total copper mg/L 14 – 14 1.2 8.95 105

01051 Total lead mg/L 14 2 12 0.09 1.365 9.14

01092 Total zinc mg/L 14 1 13 2 14 135

45501 Total petroleum hydrocarbons mg/L 12 11 1 – E4 –

70300 Total dissolved solids mg/L 12 – 12 42 78.5 98
Appendix C 65

Table C7. Statistical summary of detections and values for selected physical properties and constituents measured in composite 

samples collected at Quarantine Station.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property; mS/cm at 25°C, microsiemens per centimeter at 25 degrees 

Celsius; mg/L, milligram per liter; mg/L, microgram per liter; –, no data or not computed; E, estimated value; N, nitrogen; NO2, nitrite; NO3, nitrate; cfs, cubic 

feet per second]

USGS 

parameter 

code

Property or constituent Units

Composite Samples

Number Of Detected Values

Samples Non-Detects Detects Min. Median Max.

00010 Temperature, water degrees Celsius 2 – 2 19.7 – 21.7

00060 Discharge cfs 9 – 9 34 65 401

00095 Specific conductance, field mS/cm at 25°C 2 – 2 72 – 90

90095 Specific conductance, lab mS/cm at 25°C 9 – 9 55 86 118

00340 Chemical oxygen demand mg/L 6 – 6 40 125 380

00400 pH, field standard units 3 – 3 6.9 7.1 7.3

00403 pH, lab standard units 9 – 9 6.9 7.3 7.7

00530 Total suspended solids mg/L 8 – 8 162 654 2370

00600 Total nitrogen mg/L 7 – 7 1.325 3.8 9.9

00608 Nitrogen ammonia dissolved mg/L as N 7 7 – – – –

00613 Nitrogen, nitrite, dissolved mg/L as N 7 5 2 E0.004 – 0.016

00618 Nitrogen, nitrate, dissolved mg/L as N 1 – 1 – 0.26 –

00625 Nitrogen, total organic + ammonia mg/L as N 7 – 7 1.3 3.7 9.7

00631 Nitrogen, nitrite + nitrate dissolved mg/L as N 7 1 6 0.09 0.135 0.28

71851 Nitrate, dissolved mg/L as NO3 1 – 1 – 1.15 –

71856 Nitrite, dissolved mg/L as NO2 1 – 1 – 0.053 –

00665 Total phosphorus mg/L 7 – 7 0.28 1.07 2.6

00666 Phosphorus dissolved mg/L 7 5 2 E0.03 – E0.04

01027 Total cadmium mg/L 9 – 9 0.08 0.2 0.52

01042 Total copper mg/L 9 – 9 17.5 54.4 124

01051 Total lead mg/L 9 – 9 2.65 5.59 23.2

01092 Total zinc mg/L 9 – 9 33 85 193

70300 Total dissolved solids mg/L 8 – 8 37 52 62
66 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

Table C8. Statistical summary of detections and values for selected physical properties and constituents measured in grab samples 

collected at Stadium.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property; mS/cm at 25°C, microsiemens per centimeter at 25 degrees 

Celsius; mg/L, milligram per liter; mg/L, microgram per liter; –, no data or not computed; E, estimated value; %, percent; NTU, nephelometric turbidity unit; N, 

nitrogen; NO2, nitrite; NO3, nitrate; NH4, ammonia; mm of Hg, millimeters of mercury; cfs, cubic feet per second]

USGS 

parameter 

code

Property or constituent Units

Grab Samples

Number Of Detected Values

Samples Non-Detects Detects Min. Median Max.

00010 Temperature, water degrees Celsius 9 – 9 19.5 21.6 27.5

00020 Temperature, air degrees Celsius 1 – 1 – 26.5 –

00025 Air pressure mm of Hg 1 – 1 – 762 –

00061 Discharge, instant. cfs 10 – 10 4.8 150.5 1820

00065 Gage height feet 9 – 9 1.08 1.92 18.91

00076 Turbidity NTU 1 – 1 – 1.9 –

00095 Specific conductance mS/cm at 25°C 9 – 9 70 128 229

90095 Specific conductance, lab mS/cm at 25°C 9 – 9 78 127 232

00300 Oxygen dissolved mg/L 1 – 1 – 10 –

00301 Oxygen dissolved % of saturation 1 – 1 – 127 –

00340 Chemical oxygen demand mg/L 10 1 9 10 20 150

00400 pH, field standard units 9 – 9 5.9 7.4 9.1

00403 pH, lab standard units 9 – 9 7.2 7.5 7.9

00530 Total suspended solids mg/L 10 – 10 4 119.5 5380

00556 Oil and grease mg/L 10 8 2 E5 – E5

00600 Total nitrogen mg/L 10 – 10 0.175 0.85 5.4

00605 Organic nitrogen mg/L 1 – 1 – 0.13 –

00608 Nitrogen ammonia dissolved mg/L as N 10 9 1 – 0.03 –

00613 Nitrogen, nitrite, dissolved mg/L as N 9 4 5 E0.005 E0.007 0.009

00618 Nitrogen, nitrate, dissolved mg/L as N 1 – 1 – 0.17 –

00625 Nitrogen, total organic + ammonia mg/L as N 10 – 10 0.15 0.635 4.5

00631 Nitrogen, nitrite + nitrate dissolved mg/L as N 10 2 8 E0.04 0.23 0.91

71846 Ammonia, dissolved mg/L as NH4 1 – 1 – 0.03 –

71851 Nitrate, dissolved mg/L as NO3 1 – 1 – 0.753 –

71856 Nitrite, dissolved mg/L as NO2 2 – 2 0.02 – 0.03

00665 Total phosphorus mg/L 10 1 9 0.04 0.2 1.87

00666 Phosphorus dissolved mg/L 9 3 6 E0.02 0.04 0.07

00680 Carbon, organic, total mg/L 1 – 1 – 2.9 –

00940 Chloride, dissolved mg/L 1 – 1 – 17.4 –

00945 Sulfate, dissolved mg/L 1 – 1 – 5.8 –

01027 Total cadmium mg/L 9 4 5 0.05 0.12 0.35

01042 Total copper mg/L 9 – 9 3.7 13.1 85.2

01051 Total lead mg/L 9 2 7 0.54 3.42 25.7

01092 Total zinc mg/L 9 – 9 6 28 117

45501 Total petroleum hydrocarbons mg/L 9 7 2 2 – 3

70300 Total dissolved solids mg/L 9 – 9 44 86 136
Appendix DTable D1. Geometric means and Hawaii Department of Health criteria for nutrients and total suspended solids in grab samples at Bridge 8. [Values in bold exceed State of Hawaii Department of Health criteria; n, number of samples; Wet Season, November 1 through April 30; Dry Season, May 1 through October 31ligrams per liter]Property or constituent Season n

Geometric Mean 

Concentration

90th Percentile 

Concentration

98th Percentile 

Concentration 

HDOH 

Criteria Value HDOH Criteria Value HDOH Criteria Value

Grab Samples

Nitrogen, nitrite + nitrate, dissolved Dry 6 0.03 0.058 0.09 0.09 0.17 0.09 

Wet 5 0.07 0.144 0.18 0.2 0.3 0.2 

Total nitrogen Dry 6 0.18 0.631 0.38 1.4 0.6 1.4 

Wet 5 0.25 1.033 0.52 6.3 0.8 6.3 

Total phosphorus Dry 6 0.03 0.125 0.06 0.67 0.08 0.67 

Wet 5 0.05 0.208 0.1 1.77 0.15 1.77 

Total suspended solids Dry 6 10 70.54 30 557 55 557 

Wet 5 20 84.92 50 1,170 80 1,170 
Table D2. Geometric means and Hawaii Department of Health criteria for select nutrients, total suspended solids, and turbidity at Storm Drain C. [Values in bold exceed State of Hawaii Department of Health standards; n, number of samples; Wet Season, November 1 through April 30; Dry Season, May 1 through October per liter except Turbidity in Nephelometric Turbidity Units] Property or constituent Season n Geometric Mean Concentration 90th Percentile Concentration 98th Percentile Concentration 

HDOH Criteria Value HDOH Criteria Value HDOH Criteria Value Grab Samples Nitrogen, nitrite + nitrate, dissolved Dry 7 0.03 0.1 0.09 0.58 0.17 0.58 

Wet 13 0.07 0.09 0.18 0.17 0.3 0.55 

Total nitrogen Dry 7 0.18 0.38 0.38 0.7 0.6 0.7 

Wet 13 0.25 0.46 0.52 0.95 0.8 1.6 

Total phosphorus Dry 7 0.03 0.06 0.06 0.09 0.08 0.09 

Wet 13 0.05 0.07 0.1 0.18 0.15 0.24 

Total suspended solids Dry 12 10 12.66 30 58 55 203 

Wet 26 20 24.89 50 113 80 560 

Turbidity Dry 6 2 4.38 5.5 18 10 18 

Wet 14 5 5.24 15 21 25 22 

Composite Samples Nitrogen, nitrite + nitrate, dissolved Dry 8 0.03 0.04 0.09 0.13 0.17 0.13 

Wet 11 0.07 0.04 0.18 0.07 0.3 0.08 

Total nitrogen Dry 8 0.18 0.42 0.38 1.2 0.6 1.2 

Wet 11 0.25 0.33 0.52 0.84 0.8 1.46 

Total phosphorus Dry 9 0.03 0.12 0.06 0.25 0.08 0.25 

Wet 11 0.05 0.07 0.1 0.24 0.15 0.38 

Total suspended solids Dry 11 10 34.96 30 86 55 103 

Wet 17 20 27.85 50 95 80 96 

Turbidity Dry 5 2 2.81 5.5 4.9 10 4.9 

Wet 5 0.5 5.53 15 14 25 14 
Table D3. Geometric means and Hawaii Department of Health criteria for select nutrients, total suspended solids, and turbidity at Xeriscape Garden[Values in bold exceed State of Hawaii Department of Health standards; n, number of samples; Wet Season, November 1 through April 30; Dry Season, May 1 through October per liter except Turbidity in Nephelometric Turbidity Units; –, not calculated because of small sample size]Property or constituent Season n

Geometric Mean 

Concentration

90th Percentile 

Concentration

98th Percentile 

Concentration

HDOH 

Criteria Value HDOH Criteria Value HDOH Criteria Value 

Grab SamplesNitrogen, nitrite + nitrate, dissolved Dry 9 0.03 0.057 0.09 0.2 0.17 0.2 

Wet 13 0.07 0.094 0.18 0.21 0.3 0.35 

Total nitrogen Dry 8 0.18 0.428 0.38 1.3 0.6 1.3 

Wet 13 0.25 0.543 0.52 2.8 0.8 6.7 

Total phosphorus Dry 9 0.03 0.069 0.06 0.5 0.08 0.5 

Wet 13 0.05 0.09 0.1 1.02 0.15 2.31 

Total suspended solids Dry 12 10 36 30 306 55 440 

Wet 20 20 74 50 1,675 80 1,930 

Turbidity Dry 5 2 10 5.5 62 10 62 

Wet 11 5 50 15 320 25 380 

Composite SamplesNitrogen, nitrite + nitrate, dissolved Dry 4 0.03 – 0.09 – 0.17 – 

Wet 12 0.07 0.1 0.18 0.2 0.3 0.29 

Total nitrogen Dry 4 0.18 – 0.38 – 0.6 – 

Wet 12 0.25 2.97 0.52 8.6 0.8 14 

Total phosphorus Dry 4 0.03 – 0.06 – 0.08 – 

Wet 12 0.05 0.62 0.1 1.75 0.15 3.51 

Total suspended solids Dry 9 10 91 30 536 55 536 

Wet 25 20 219 50 1,700 80 2,420 

Turbidity Dry 5 2 21.7 5.5 27 10 27 

Wet 10 5 67.42 15 325 25 390 
Table D4. Geometric means and Hawaii Department of Health criteria for select nutrients and total suspended solids at Quarantine Station. [Values in bold exceed State of Hawaii Department of Health standards; n, number of samples; Wet Season, November 1 through April 30; Dry Season, May 1 through October per liter; –, not calculated because of small sample size] Property or constituent Season n Geometric Mean Concentration 90th Percentile Concentration 98th Percentile Concentration 

HDOH Criteria Value HDOH Criteria Value HDOH Criteria Value Grab Samples Nitrogen, nitrite + nitrate, dissolved Dry 6 0.03 0.102 0.09 0.26 0.17 0.26 

Wet 5 0.07 0.18 0.18 0.24 0.3 0.24 

Total nitrogen Dry 6 0.18 0.68 0.38 1.5 0.6 1.5 

Wet 5 0.25 1.108 0.52 4.3 0.8 4.3 

Total phosphorus Dry 6 0.03 0.142 0.06 0.53 0.08 0.53 

Wet 5 0.05 0.265 0.1 2.06 0.15 2.06 

Total suspended solids Dry 6 10 59.581 30 368 55 368 

Wet 6 20 62.921 50 769 80 769 

Composite Samples Nitrogen, nitrite + nitrate, dissolved Dry 2 0.03 – 0.09 – 0.17 – 

Wet 5 0.07 0.125 0.18 0.22 0.3 0.22 

Total nitrogen Dry 2 0.18 – 0.38 – 0.6 – 

Wet 5 0.25 4.447 0.52 9.9 0.8 9.9 

Total phosphorus Dry 2 0.03 – 0.06 – 0.08 – 

Wet 5 0.05 1.185 0.1 2.6 0.15 2.6 

Total suspended solids Dry 2 10 – 30 – 55 – 

Wet 6 20 675.339 50 2,370 80 2,370 
Table D5. Geometric means and Hawaii Department of Health criteria for select nutrients and total suspended solids at Stadium.[Values in bold exceed State of Hawaii Department of Health standards; n, number of samples; Wet Season, November 1 through April 30; Dry Season, May 1 through October per liter]Property or constituent Season n

Geometric Mean 

Concentration

90th Percentile 

Concentration

98th Percentile 

Concentration 

HDOH 

Criteria Value HDOH Criteria Value HDOH Criteria Value

Grab SamplesNitrogen, nitrite + nitrate, dissolved Dry 5 0.03 0.092 0.09 0.43 0.17 0.43 

Wet 5 0.07 0.264 0.18 0.91 0.3 0.91 

Total nitrogen Dry 5 0.18 1.147 0.38 4.6 0.6 4.6 

Wet 5 0.25 0.879 0.52 5.4 0.8 5.4 

Total phosphorus Dry 5 0.03 0.256 0.06 1.56 0.08 1.56 

Wet 5 0.05 0.142 0.1 1.87 0.15 1.87 

Total suspended solids Dry 5 10 444.578 30 5,380 55 5,380 

Wet 5 20 57.63 50 1,260 80 1,260 
72 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

Appendix E

Table E1. Spearman correlation coefficients and associated significance probabilities for storm characteristics at Storm Drain C.

[Upper number is the Spearman correlation coefficient (r), lower number is the probability that the null hypothesis of no correlation is true (p); numbers in bold

have Spearman correlation coefficients greater than 0.5 and significance probabilities less than or equal to 0.05; Spearman correlation coefficients with significance probabilities (p) greater than 0.05 are not shown; significance probabilities less than 0.005 are reported as 0.00; See table 6 for explanation of abbreviated 

terms]

VOLtwa

Qtwa

QMax

TOTR

RDUR

VDS

IVOL

OINT

SDUR

SVOLtwa

sQtwa

SQMax

TOTRs

SRDUR

SVDS

DUR 0.76 0.32 0.78 0.98 0.9 0.32 0.79 0.6 -0.24 0.65 0.78 0.72

0.00 0.01 0.00 0.00 0.00 0.01 0.00 0.00 0.04 0.00 0.00 0.00

VOLtwa 0.53 0.78 0.96 0.78 0.76 0.78 0.53 0.57 0.75 0.3 0.57 0.79 0.61 0.57

0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00

Qtwa 0.81 0.47 0.81 1 0.37 0.77 0.72 0.35

0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

QMax 0.75 0.36 0.38 1 0.81 0.23 0.62 0.61 0.81 0.58 0.32

0.00 0.00 0.00 0.00 0.00 0.05 0.00 0.00 0.00 0.00 0.01

TOTR 0.81 0.78 0.75 0.47 0.6 0.77 0.29 0.56 0.81 0.61 0.59

0.00 0.00 0.00 0.00 0.00 0.00 0.02 0.00 0.00 0.00 0.00

RDUR 0.93 0.36 0.77 0.62 0.67 0.79 0.75

0.00 0.00 0.00 0.00 0.00 0.00 0.00

VDS 0.38 0.72 0.61 0.66 0.75 0.8

0.00 0.00 0.00 0.00 0.00 0.00

IVOL 0.81 0.23 0.62 0.61 0.81 0.58 0.32

0.00 0.05 0.00 0.00 0.00 0.00 0.01

OINT 0.37 0.77 0.72 0.35

0.00 0.00 0.00 0.00

SDUR 0.8 0.31 0.77 0.93 0.9

0.00 0.01 0.00 0.00 0.00

SVOLtwa 0.39 0.74 0.92 0.76 0.75

0.00 0.00 0.00 0.00 0.00

sQtwa 0.75 0.3

0.00 0.01

SQMax 0.66 0.29 0.37

0.00 0.01 0.00

TOTRs 0.831 0.737

0.00 0.00

SRDUR 0.86

0.00
Appendix E 73

Table E2. Spearman correlation coefficients and associated 

significance probabilities for the preceding-storm characteristics 

at Storm Drain C.

[Upper number is the Spearman correlation coefficient (r), lower number is 

the probability that the null hypothesis of no correlation is true (p); numbers in 

bold have Spearman correlation coefficients greater than 0.5 and significance 

probabilities less than or equal to 0.05; significance probabilities (p) less than 

0.005 are reported as 0.00; see table 6 for explanation of abbreviated terms]

PQtwa PVOLtwa POINT PQMax PIVOL

PDUR 0.02 0.87 0.02 0.45 0.44

0.88 0.00 0.88 0.00 0.00

PQtwa 0.38 1 0.77 0.77

0.00 0.00 0.00 0.00

PVOLtwa 0.38 0.69 0.69

0.00 0.00 <0.00

POINT 0.77 0.77

0.00 0.00

PQMax 1

0.00
Table E3. Simple statistics for constituents used in Spearman Rank Correlation from Storm Drain C. [n, number of samples; Std Dev, Standard deviation; ROS, regression on statistics; mS/cm at 25°C, microsiemens per centimeter at 25 degrees Celsius; mg/L, milligrams per liter

NTU, nephelometric turbidity unit] Property or constituent Units n Mean Std Dev Number of ROS estimated values Minimum Detected 

Chemical oxygen demand mg/L 35 24.2 18.8 10 10 

Nitrogen, nitrite + nitrate, dissolved mg/L 36 0.1 0.1 10 0.06 

Nitrogen, ammonia + organic, total mg/L 37 0.4 0.4 1 0.1 

Specific conductance mS/cm at 25°C 25 82.2 57.7 0 25 

Specific conductance, lab mS/cm at 25°C 50 71.8 44.8 0 28 Total cadmium mg/L 36 0.2 0.2 1 0.04 

Total copper mg/L 49 25.7 26.9 0 1.4 Total dissolved solids mg/L 30 39.6 35.1 0 15 

Total lead mg/L 49 8.2 9.1 3 1 

Total nitrogen mg/L 36 0.5 0.4 0 0.08 

Total phosphorus mg/L 37 0.1 0.1 3 0.06 

Total suspended solids mg/L 63 52.7 83 13 10 

Total zinc mg/L 49 94.1 72.1 0 12 

Turbidity NTU 30 6.4 5.9 0 1.3 
Appendix E 75

Table E4. Spearman rank correlation coefficients and associated significance probabilities for group A constituents from Storm 

Drain C.

[The upper number is the Spearman rank correlation coefficients (r), the middle number is the probability that the null hypothesis of no correlation is true (p), 

and the number in parenthesis () is the number of samples used in the calculation; significance probabilities (p) less than 0.005 are reported as 0.00; correlation 

coefficients in bold indicate significance probabilities less than or equal to 0.05]

Property or constituent

Total suspended 

solids

Total nitrogen

Nitrogen, ammonia 

+ organic, total

Total phosphorus

Total cadmium

Total copper

Total lead

Total zinc

Chemical oxygen demand 0.66 0.64 0.72 0.67 0.68 0.68 0.69 0.77

0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

(35) (34) (35) (35) (25) (34) (34) (34)

Total suspended solids 0.72 0.82 0.79 0.88 0.88 0.84 0.86

0.00 0.00 0.00 0.00 0.00 0.00 0.00

(36) (37) (37) (41) (41) (41) (41)

Total nitrogen 0.89 0.79 0.58 0.73 0.74 0.77

0.00 0.00 0.00 0.00 0.00 0.00

(36) (36) (25) (35) (35) (35)

Nitrogen, ammonia + organic, total 0.84 0.74 0.87 0.88 0.88

0.00 0.00 0.00 0.00 0.00

(37) (25) (35) (35) (35)

Total phosphorus 0.88 0.88 0.9 0.85

0.00 0.00 0.00 0.00

(35) (35) (35) (35)

Total cadmium 0.87 0.86 0.8

0.00 0.00 0.00

(36) (36) (36)

Total copper 0.97 0.91

0.00 0.00

(49) (49)

Total lead 0.9

0.00

(49)
76 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

Table E5. Spearman rank correlation coefficients and associated significance probabilities for group B constituents from Storm 

Drain C.

[The upper number is the Spearman rank correlation coefficient (r), the middle number is the probability that the null hypothesis of no correlation is true (p), and 

the number in parenthesis () is the number of samples used in the calculation; significance probabilities (p) less than 0.005 are reported as 0.00; correlation coefficients in bold indicate significance probabilities less than or equal to 0.05; –, not calculated]

Property or constituent

Specific 

conductance, 

field

Specific 

conductance, 

lab

Total 

dissolved 

solids

Turbidity

Nitrogen, nitrite + nitrate, dissolved 0.82 0.79 0.77 0.23

0.00 0.00 0.00 0.53

(22) (36) (27) (10)

Specific conductance 0.98 0.96 0.67

0.00 0.00 0.05

(23) (16) (9)

Specific conductance, lab 0.92 0.63

0.00 0.02

(30) (13)

Total dissolved solids –

–

(2)
Appendix E 77

Table E6. Spearman rank correlation coefficients and associated significance probabilities for composite sample constituents and 

storm characteristics from Storm Drain C—Continued.

[The upper number is the Spearman rank correlation coefficients (r), the middle number is the probability that the null hypothesis of no correlation is true (p), 

and the number in parenthesis () is the number of samples used in the calculation; significance probabilities (p) less than 0.005 are reported as 0.00; only correlation coefficients with significance probabilities less than or equal to 0.05 are shown; values in bold indicate correlation coefficients greater than or equal to 0.50; 

negative correlation coefficients indicate inverse relationships; see table 6 for explanation of abbreviated terms] COD Specific conductance, (Lab) Specific conductance, (field) Total Nitrogen Nitrogen, ammonia + organic, total Nitrogen, nitrite + nitrate, dissolved Total Phosphorus TSS TDS

CuPb

Zn

Cd

DUR – -0.43 – – – -0.53 – -0.43 -0.55 -0.47 -0.49 -0.41 –

– 0.03 – – – 0.02 – 0.04 0.02 0.02 0.01 0.04 –

– (24) – – – (19) – (24) (17) (24) (24) (24) –

VOLtwa -0.48 -0.76 -0.85 -0.49 -0.51 -0.71 -0.61 -0.54 -0.71 -0.57 -0.67 -0.65 –

0.04 0.00 0.01 0.03 0.02 0.00 0.01 0.01 0.00 0.00 0.00 0.00 –

(19) (24) (8) (19) (19) (19) (19) (24) (17) (24) (24) (24) –

Qtwa – -0.63 -0.73 – – – – – – – – – –

– 0.00 0.04 – – – – – – – – – –

– (24) (8) – – – – – – – – – –

QMax – -0.79 -0.83 – – -0.5 – – -0.6 – -0.5 -0.47 –

– 0.00 0.01 – – 0.03 – – 0.01 – 0.01 0.02 –

– (24) (8) – – (19) – – (17) – (24) (24) –

TOTR – -0.76 -0.9 -0.49 -0.51 -0.64 -0.65 -0.55 -0.72 -0.63 -0.72 -0.66 –

– 0.00 0.00 0.03 0.03 0.00 0.00 0.00 0.00 0.00 0.00 0.00 –

– (24) (8) (19) (19) (19) (19) (24) (17) (24) (24) (24) –

RDUR – -0.5 – – – – -0.56 -0.49 – -0.56 -0.57 -0.49 –

– 0.01 – – – – 0.01 0.02 – 0.00 0.00 0.01 –

– (24) – – – – (19) (24) – (24) (24) (24) –

VDS – – – – – – – – – -0.44 -0.43 – –

– – – – – – – – – 0.03 0.04 – –

– – – – – – – – – (24) (24) – –

IVOL – -0.79 -0.83 – – -0.5 – – -0.6 – -0.5 -0.46 –

– 0.00 0.01 – – 0.03 – – 0.01 – 0.01 0.02 –

– (24) (8) – – (19) – – (17) – (24) (24) –

OINT – -0.63 -0.73 – – – – – – – – – –

– 0.00 0.04 – – – – – – – – – –

– (24) (8) – – – – – – – – – –

SDUR -0.54 -0.48 – – – -0.67 -0.56 -0.41 -0.59 -0.47 -0.5 –

0.02 0.02 – – – 0.00 0.01 0.04 0.01 0.02 0.01 –

(19) (24) – – – (19) (19) (24) (17) (24) (24) –

SVOLtwa -0.64 -0.78 -0.83 -0.56 -0.58 -0.64 -0.71 -0.56 -0.64 -0.51 -0.65 -0.67 –

0.00 0.00 0.01 0.01 0.01 0.00 0.00 0.00 0.01 0.01 0.00 0.00 –

(19) (24) (8) (19) (19) (19) (19) (24) (17) (24) (24) (24) –

sQtwa – -0.6 – – – – – – – – -0.45 -0.41 –

– 0.00 – – – – – – – – 0.03 0.05 –

– (24) – – – – – – – – (24) (24) –

SQMax -0.48 -0.78 -0.87 – – -0.53 -0.54 – -0.6 – -0.53 -0.48 –

0.04 0.00 0.00 – – 0.02 0.02 – 0.01 – 0.01 0.02 –

(19) (24) (8) – – (19) (19) – (17) – (24) (24) –

TOTRs -0.54 -0.77 -0.85 – – -0.52 -0.61 -0.56 -0.58 -0.5 -0.64 -0.61 –

0.02 0.00 0.01 – – 0.03 0.01 0.00 0.02 0.01 0.00 0.00 –

(18) (23) (8) – – (18) (18) (23) (16) (23) (23) (23) –

RsDUR – -0.42 – – – -0.68 – – -0.53 – – -0.47 –

– 0.04 – – – 0.00 – – 0.04 – – 0.02 –

– (23) – – – (18) – – (16) – – (23) –

SVDS – -0.43 – – – -0.51 -0.45 – – – – – –

– 0.03 – – – 0.03 0.05 – – – – – –

– (24) – – – (19) (19) – – – – – –

Table E6. Spearman rank correlation coefficients and associated significance probabilities for composite sample constituents and 

storm characteristics from Storm Drain C.

[The upper number is the Spearman rank correlation coefficients (r), the middle number is the probability that the null hypothesis of no correlation is true (p), 

and the number in parenthesis () is the number of samples used in the calculation; significance probabilities (p) less than 0.005 are reported as 0.00; only correlation coefficients with significance probabilities less than or equal to 0.05 are shown; values in bold indicate correlation coefficients greater than or equal to 0.50; 

negative correlation coefficients indicate inverse relationships; see table 6 for explanation of abbreviated terms]
78 H-3 Highway Stormwater Runoff and Water Quality of Halawa Stream, November 1998 to August 2004

Table E6. Spearman rank correlation coefficients and associated significance probabilities for composite sample constituents and 

storm characteristics from Storm Drain C—Continued.

[The upper number is the Spearman rank correlation coefficients (r), the middle number is the probability that the null hypothesis of no correlation is true (p), 

and the number in parenthesis () is the number of samples used in the calculation; significance probabilities (p) less than 0.005 are reported as 0.00; only correlation coefficients with significance probabilities less than or equal to 0.05 are shown; values in bold indicate correlation coefficients greater than or equal to 0.50; 

negative correlation coefficients indicate inverse relationships; see table 6 for explanation of abbreviated terms] COD Specific conductance, (Lab) Specific conductance, (field) Total Nitrogen Nitrogen, ammonia + organic, total Nitrogen, nitrite + nitrate, dissolved Total Phosphorus TSS TDS

CuPb

Zn

Cd

PDUR -0.59 – – – – – – -0.44 – – – -0.43 –

0.01 – – – – – – 0.03 – – – 0.03 –

(19) – – – – – – – – – – (24) –

PVOLtwa -0.56 – – – – – – -0.42 – – – – -0.53

0.01 – – – – – – 0.04 – – – – 0.03

(19) – – – – – – – – – – – (16)

SQmaxP -0.46 – – – – -0.65 – – – – – – –

0.04 – – – – 0.00 – – – – – – –

(19) – – – – (19) – – – – – – –
Wolff and Wong—Effects of the H-3 Highway Stormwater Runoff on the Water Quality of Halawa Stream, Oahu, Hawaii, 

November 1998 to August 2004—Report Series Name 0000

Effects of the H-3 Highway Stormwater Runoff on the Water Quality of Halawa Stream, Oahu, Hawaii, November 1998 to 

August 2004—Scientific Investigations Report 2008–5034