Effects of Surface-Water Diversion on Streamflow, 

Recharge, Physical Habitat, and Temperature, 

Na ̄ Wai ÿEha ̄, Maui, Hawaiÿi

Scientific Investigations Report 2010–5011

U.S. Department of the Interior

U.S. Geological Survey

Prepared in Cooperation with the County of Maui Office of Economic Development, 

County of Maui Department of Water Supply, State of Hawaiÿi Commission on Water 

Resource Management, State of Hawaiÿi Office of Hawaiian Affairs
Back Front

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12

About the cover: Native fish in South Waiehu Stream: 

1, 3, 6, 7, 8, and 11, ÿoÿopu näkea; 

2, 4, 5, and 10, ÿoÿopu ÿalamoÿo;

9 and 12, ÿoÿopu nöpili. 

Photograph by Reuben H. Wolff.
Effects of Surface-Water Diversion on Streamflow, 

Recharge, Physical Habitat, and Temperature, 

Na ̄ Wai ‘Eha ̄, Maui, Hawai‘i

By Delwyn S. Oki, Reuben H. Wolff, and Jeff A. Perreault

Scientific Investigations Report 2010–5011

U.S. Department of the Interior

U.S. Geological Survey 

Prepared in Cooperation with the County of Maui Office of Economic Development, County 

of Maui Department of Water Supply, State of Hawaiÿi Commission on Water Resource 

Management, State of Hawaiÿi Office of Hawaiian Affairs
ii

U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2010

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Suggested citation:

Oki, D.S., Wolff, R.H., and Perreault, J.A., 2010, Effects of surface-water diversion on streamflow, recharge, physical habitat, and temperature, Na ̄ Wai ÿEha ̄, Maui, Hawaiÿi: U.S. Geological Survey Scientific Investigations Report 

2010–5011, 154 p.

Cataloging-in-publication data are on file with the Library of Congress (http://catalog.loc.gov/).
 iii

This report presents results of a study to characterize the 

effects of existing surface-water diversions on streamflow, 

groundwater recharge, physical habitat for native stream 

fauna, and water temperature in Waihe‘e River, Waiehu 

Stream, ‘Īao Stream, and Waikapū Stream, collectively 

known as Nā Wai ‘Ehā (“The Four Streams”), Maui, Hawai‘i 

(fig. ES1). This study arose out of a need for additional 

scientific information related to the surface-water resources 

in the Nā Wai ‘Ehā area. Existing diversions are capable of 

diverting all or nearly all of the dry-weather flows of these 

streams, leaving some downstream reaches dry. A lack of 

sufficient water downstream of existing diversions has led to 

recent conflicts between those currently (2009) diverting or 

using the water and those desiring sufficient instream flows 

for protection of traditional and customary Hawaiian rights 

(including the cultivation of taro), maintenance of habitat for 

native stream fauna, recreation, and aesthetics. The County 

of Maui Department of Water Supply currently withdraws 

groundwater from the aquifers potentially recharged by 

these streams. Thus, an understanding of the effects of the 

diversions on groundwater recharge also is essential for 

proper planning and management of the resource. Factors 

that likely will play a role in future planning and management 

decisions include (1) the use of stream water for agriculture, 

protection of traditional and customary Hawaiian rights, and 

maintenance of ecologic balance, (2) aesthetic differences 

between dry and flowing streams, and (3) recreational use of 

the streams (fishing, swimming). The U.S. Geological Survey 

(USGS) undertook the present investigation in cooperation 

with the County of Maui Office of Economic Development, 

County of Maui Department of Water Supply, State of 

Hawai‘i Commission on Water Resource Management, and 

State of Hawai‘i Office of Hawaiian Affairs. 

General Characteristics of Streams

The streams of the Nā Wai ‘Ehā area flow in their 

upper reaches even during extended dry-weather conditions 

because of persistent groundwater discharge to the streams. 

The lower reaches of these streams generally lose water, 

which may contribute to groundwater recharge. During 

1984–2007, Waihe‘e River had the greatest median natural, 

undiverted flow (upstream of the uppermost diversion) 

of the four streams. The median undiverted flows during 

climate years 1984–2007 were 34 Mgal/d (million gallons 

per day) for Waihe‘e River near an altitude of 605 feet; 25 

Mgal/d for ‘Īao Stream near an altitude of 780 feet; and 

estimated to be about 4.3 Mgal/d for Waikapū Stream near 

an altitude of 1,160 feet; 3.2 Mgal/d for South Waiehu 

Stream near an altitude of 870 feet; and 3.2 Mgal/d for 

North Waiehu Stream near an altitude of 880 feet. As of 

2009, water is diverted from each stream by three to five 

diversion intakes (table ES1; fig. ES2). Hourly photographs 

collected during 2006–2008 indicate that some stream 

reaches downstream of diversions are dry more than 50 

percent of the time (fig. ES3). Many of these reaches 

would be perennial or nearly perennial in the absence of 

diversions. 

Stream Fauna

Snorkel surveys during 2008 identified the presence of 

native fauna in each of the Nā Wai ‘Ehā streams. Native fauna 

observed in the Nā Wai ‘Ehā streams include an endemic 

mountain shrimp (‘ōpae); endemic gobies (‘o‘opu ‘alamo‘o 

and ‘o‘opu nōpili); an indigenous goby (‘o‘opu nākea); and 

an endemic eleotrid (‘o‘opu ‘akupa). During the period of 

this study, ‘o‘opu ‘alamo‘o, ‘o‘opu nōpili, and ‘o‘opu nākea 

were observed in each of Waihe‘e River, ‘Īao Stream, and 

Waiehu Stream (see cover photograph), although only a single 

unidentified individual ‘o‘opu was observed in Waikapū 

Stream. The amphidromous life cycle (requiring time in 

both the ocean and the stream) of the native fauna requires 

stream connectivity to the ocean to enable recruitment, and 

any condition that impedes the mauka to makai (mountain to 

ocean) connectivity can affect the distribution and abundance 

of the amphidromous fauna.

Mauka to Makai Flows

Each of the Nā Wai ‘Ehā streams generally loses water, 

by infiltration into the streambed, over its lower reaches 

downstream of diversions. If no water had been diverted 

from the Nā Wai ‘Ehā streams during climate years 1984–

2007, Waihe‘e River and ‘Īao Stream would have flowed 

continuously to the coast; Waiehu Stream would have flowed 

continuously to the coast at least 95 percent of the time; and 

Waikapū Stream would have flowed continuously to the coast 

less than half of the time. The minimum undiverted flows, 

upstream of the uppermost diversion in each stream, necessary 

to maintain continuous flow near the coast, are: 1 Mgal/d for 

Waihe‘e River; 1.3 Mgal/d for North Waiehu Stream and 1.1 

Mgal/d for South Waiehu Stream; 5.2 Mgal/d for ‘Īao Stream; 

and 6.8 Mgal/d for Waikapū Stream. 

Groundwater Recharge

Because each stream loses water in its lower reaches, 

these streams represent potential sources of groundwater 

recharge for the underlying aquifer. For natural, undiverted 

Executive Summary
iv

Waihe‘e Ditch

Waihe‘e Ditch

Kama Ditch

N. Waiehu Dt

South Waikapü Dt

Spreckels Ditch

‘Ïao–Mäniania Ditch Everett

Dt

Spreckels Ditch

ÿÏao–Waikapü Ditch

Waiheÿe Ditch

Waiheÿe River

Waiehu Str

North

Waiehu Stream

South Waiehu

Stream

ÿÏao

Stream

Waikapü

Stream

Huluhulupueo Str

Mananole Str

Waiheÿe

River

Ae Stream

Kinihäpai

Po

Str

ÿonähoahoa Str

Näkalaloa Str

Ukumehame Gulch

 

Olowalu

Stream

Pöhäkea

Gulch

Manawainui Gulch

Honoköhau

Stream

Mokulele Highway

Kahekili Highway

340

340

36

30

30

30

31

380

380

Pu‘u Kukui

P A C I F I C

O C E A N

34

(1.0)

34

(1.7)

34

(1.0)

3.2

(1.3)

3.2

(1.1)

3.9

(0.3)

2.3

(0.1)

25

(5.2)

23

(2.1)

4.3

(6.8)

5.3

(8.0)

0

(2.1)

Kahului

Harbor

Keälia Pond

Waiheÿe Pt

Nehe Pt

McGregor Pt

Mä‘alaea

Papawai Pt

Waihe‘e

Waiehu

Kahului

Wailuku

Wailuku

Heights

Base modified from U.S. Geological Survey National 

Hydrography Dataset. Universal Transverse Mercator

projection, zone 4, NAD83 datum. Relief from U.S. 

Geological Survey digital elevation models, 1:24,000. 

EXPLANATION

LOSING REACH OF STREAM

CONCRETE CHANNEL

DITCH SYSTEM

INFERRED BOUNDARY BETWEEN DIKE-IMPOUNDED

 AND FRESHWATER-LENS SYSTEMS (Modified 

 from Yamanaga and Huxel, 1970)

SITE OF EXISTING DIVERSION INTAKE--

 Upper number indicates median undiverted discharge, 

 in million gallons per day, during climate years 1984-2007;

 Lower number in parentheses indicates minimum

 natural discharge, in million gallons per day, needed for 

 continuous flow near the coast

MISCELLANEOUS SITE--

 Upper number indicates median undiverted discharge, 

 in million gallons per day, during climate years 1984-2007;

 Lower number in parentheses indicates minimum

 natural discharge, in million gallons per day, needed for 

 continuous flow near the coast

25

(5.2)

3.2

(1.1)

0

0 1 2 3 KILOMETERS

0.5 1 2 MILES

156°35' 156°30'

20°50'

20°55'

PACIFIC OCEAN

Maui

Area

of map

Figure ES1 Figure ES1. . Streams, diversion intakes, and major ditch systems, Nä Wai ÿEhä area, Maui, Hawaiÿi. Streams, diversion intakes, and major ditch systems, Na ̄ Wai ÿEha ̄ area, Maui, Hawaiÿi.
 v

by identifying diversion intake capacities that will lead to an 

acceptable reduction in groundwater recharge.

Physical Habitat

Diversion of surface water from a stream generally 

reduces the amount of physical habitat available for native 

stream fauna during low-flow conditions. A generalized 

relation between physical habitat and discharge developed 

for this study indicates that if diversions reduce streamflow to 

half of the natural, undiverted Q70 discharge (discharge that 

Figure ES2. Photograph of a typical diversion intake 

that commonly stretches across the entire low-flow channel of a stream (Reservoir 6 intake on Waikapu ̄ Stream, 

Maui, Hawaiÿi, March 17, 2005). Water that enters the 

intake grate drains into a collection sump and flows by 

gravity into a ditch system.

Figure ES3. Photograph of dry streambed caused by 

upstream diversions, ÿĪao Stream, Maui, Hawaiÿi (September 

22, 2006).

Table ES1. Surface-water diversion intakes, Na− Wai ÿEha−, Maui, 

Hawaiÿi.

[—, data not available; Mgal/d, million gallons per day]

Intake of ditch system 

or small private ÿauwai 

(ditch)

Altitude,

in feeta

Design 

capacity,

in Mgal/d

Intake capacity 

setting,

in Mgal/d

Waiheÿe River

Waiheÿe Ditch 600 b

60 c40

Spreckels Ditch 400 b

30 c12

Field 1 260 — —

North Waiehu Stream

North Waiehu Ditch 880 — c

1.5

South Waiehu Stream

Left (north) ÿauwai 620 — —

Right (south) ÿauwai 570 — —

Spreckels Ditch 270 —d —d

ÿÏao Stream

ÿÏao-Waikapü and 

ÿÏao-Mäniania 

Ditches

780 b

60 c20

Right (south) ÿauwai 650 — —

Spreckels Ditch 250 —e —e

Waikapü Stream

South Side Ditch 1,120 b

5 c3

Everett (Palolo) Ditch 900 — —

Left (north) ÿauwai 560 — —

Waiheÿe Ditch 440 —d —d

Reservoir 6 410 —d —d

a

Altitude determined from topographic map.

b

Suzuki (2007). 

c

Gate setting (Suzuki, 2007). 

d

Capacity unknown but greater than 1 Mgal/d.

e

Capacity unknown but likely greater than 10 Mgal/d.

low-flow conditions (when flow is less than or equal to the 

median flow) the estimated average seepage loss from each 

stream, downstream of the uppermost diversion, is: 1.7 Mgal/d 

for Waihe‘e River; 2.9 Mgal/d for North Waiehu Stream, 

South Waiehu Stream, and Waiehu Stream; 5.6 Mgal/d for 

‘Īao Stream; and 4.3 Mgal/d for Waikapū Stream. Existing 

surface-water diversions in Waihe‘e River, ‘Īao Stream, 

and Waikapū Stream are capable of reducing the amount of 

recharge during periods of low flow by more than 80 percent 

relative to undiverted conditions, and existing diversions in 

Waiehu Stream are capable of reducing the amount of recharge 

by more than 33 percent. This potential loss in groundwater 

recharge may affect the quantity of groundwater that can be 

developed from the underlying aquifer, which is important to 

the water supply of the island. This report presents families of 

curves that show the relation between surface-water diversion 

capacities and recharge reduction (see figs. 58–61). These 

curves can be used to assist with water-management decisions 
vi

is equaled or exceeded 70 percent of the time), which is an 

indicator of median base-flow conditions, then habitat will 

be reduced to about 80 percent of what it would be at the Q70

discharge (fig. ES4). During some periods, physical habitat 

is reduced to zero in stream reaches that are dry because of 

surface-water diversions. This report presents families of 

curves for each stream (see figs. 69–72) that can be used to 

quantify the reduction in habitat downstream of all diversions 

for different diversion capacities. These curves can be used 

to assist with water-management decisions by identifying 

diversion intake capacities that will accommodate a target 

habitat quantity.

Temperature

During September 2006 to October 2007, when water 

temperatures in the streams were measured for this study, 

daily maximum temperatures did not exceed 27°C and daily 

minimum temperatures did not drop below 15°C at any of 

the 18 study sites. At all of the study sites, daily maximum 

temperatures remained below the upper-lethal-temperature 

limits for native aquatic species, as well as below the 

temperature that favors Pythium rot of taro. Water temperatures 

may decrease at some sites downstream of existing diversions 

if flow is restored to streams, although the effects of reduced 

temperatures on taro cultiviation were not studied. 

Additional Information and Research Needs

Streamflow characteristics estimated for this study can be 

more precisely determined by establishing long-term, continuousrecord stream-gaging stations at selected sites of interest upstream 

of diversions in Waiehu and Waikapū Streams and downstream 

of diversions in all streams. These gaging stations also would 

provide useful information for quantifying streamflow losses and 

groundwater recharge. Restoration of diverted water at different 

rates for extended periods (exceeding a few weeks) would allow 

better characterization of the effects of surface-water diversions 

on recharge and physical habitat. This study does not predict the 

effects of flow restoration on native species abundance, nor does 

this study address water requirements for taro cultivation and 

aesthetic or recreational uses, algae and invertebrate food sources 

for native macrofauna, or reproduction of native species. 

curve fit to data

0 20 40 60 80

DISCHARGE, IN PERCENTAGE OF NATURAL Q70 DISCHARGE

100 120 140 160

0

20

40

60

80

100

120

140

HABITAT (WEIGHTED USABLE AREA),

IN PERCENTAGE OF HABITAT AT NATURAL Q70 DISCHARGE

Figure ES4. Generalized relation between habitat and discharge for ÿoÿopu ÿalamoÿo, ÿoÿopu nöpili, 

ÿoÿopu näkea, ÿöpaekalaÿole, and hïhïwai in Waiheÿe River and Waiehu, ÿÏao, and Waikapü Streams, 

Maui, Hawaiÿi. The Q70 discharge is the discharge that is equaled or exceeded 70 percent of the time.

Figure ES4. Generalized relation between habitat and discharge for ÿoÿopu ÿalamoÿo, ÿoÿopu no ̄pili, 

ÿoÿopu na ̄kea, ÿo ̄paekalaÿole, and hïhïwai in Waiheÿe River and Waiehu, ÿĪao, and Waikapu ̄ Streams, 

Maui, Hawaiÿi. The Q70 discharge is the discharge that is equaled or exceeded 70 percent of the time.
 vii

Contents

Executive Summary......................................................................................................................................iii

General Characteristics of Streams .................................................................................................iii

Stream Fauna........................................................................................................................................iii

Mauka to Makai Flows........................................................................................................................iii

Groundwater Recharge ......................................................................................................................iii

Physical Habitat ....................................................................................................................................v

Temperature..........................................................................................................................................vi

Additional Information and Research Needs..................................................................................vi

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

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

Purpose and Scope ..............................................................................................................................5

Acknowledgments................................................................................................................................5

Setting .............................................................................................................................................................5

Land Use.................................................................................................................................................6

Climate....................................................................................................................................................6

Rainfall...........................................................................................................................................7

Hydrogeologic Setting .........................................................................................................................7

Geology..........................................................................................................................................7

Surface-Water Resources .......................................................................................................11

Groundwater Resources ..........................................................................................................13

Interaction Between Groundwater and Surface Water......................................................13

Potential Effects of Groundwater Withdrawals on Streamflow ........................................14

Stream Fauna................................................................................................................................................16

Native Species ....................................................................................................................................16

Life-History Characteristics of Native Species .............................................................................19

Non-Native Species ...........................................................................................................................19

Aquatic Fauna in Na ̄ Wai ÿEha ̄ Streams...........................................................................................22

Native Species ...........................................................................................................................22

Waiheÿe River ....................................................................................................................22

Waiehu Stream..................................................................................................................22

ÿĪao Stream.........................................................................................................................22

Waikapu ̄ Stream................................................................................................................30

Non-Native Species ..................................................................................................................30

Waiheÿe River ....................................................................................................................30

Waiehu Stream..................................................................................................................30

ÿĪao Stream.........................................................................................................................30

Waikapu ̄ Stream ...............................................................................................................31

Potential Factors Affecting Abundances of Native Species.......................................................31

Waiheÿe River .............................................................................................................................31

Waiehu Stream...........................................................................................................................31

ÿĪao Stream..................................................................................................................................31

Waikapu ̄ Stream.........................................................................................................................33

Artificial Transport of Postlarvae ............................................................................................33
viii

Ditch System...............................................................................................................................34

Larvae and Postlarvae ..............................................................................................................34

Other Issues Not Investigated..........................................................................................................34

Natural, Undiverted Low-Flow Characteristics ......................................................................................34

Gaging-Station Data...........................................................................................................................34

Waiheÿe River.............................................................................................................................35

ÿĪao Stream..................................................................................................................................35

Waiehu and Waikapu ̄ Streams................................................................................................35

Record-Extension Method ..............................................................................................46

Estimated Streamflow During 1984–2007......................................................................46

Limitations..........................................................................................................................47

Seepage-Run Measurements...........................................................................................................52

Waiheÿe River .............................................................................................................................58

Stream Altitudes of 585 to 400 Feet................................................................................58

Stream Altitudes of 400 to 100 Feet................................................................................58

Stream Altitudes of 100 to 45 Feet..................................................................................59

Waiehu Stream...........................................................................................................................59

North Waiehu Stream ......................................................................................................59

 Stream Altitudes of 920 to 475 Feet.......................................................................59

Stream Altitudes of 475 to 280 Feet.......................................................................59

Stream Altitudes of 280 to 220 Feet.......................................................................61

South Waiehu Stream......................................................................................................61

Stream Altitudes of 870 to 670 Feet.......................................................................61

Stream Altitudes of 670 to 535 Feet.......................................................................61

Stream Altitudes of 535 to 405 Feet.......................................................................61

Stream Altitudes of 405 to 280 Feet.......................................................................61

Stream Altitudes of 280 to 220 Feet.......................................................................61

Waiehu Stream..................................................................................................................61

Stream Altitudes of 220 to 190 Feet.......................................................................62

Stream Altitudes of 190 to 20 Feet.........................................................................62

ÿĪao Stream..................................................................................................................................62

Stream Altitudes of 780 to 725 Feet................................................................................63

Stream Altitudes of 725 to 595 Feet................................................................................63

Stream Altitudes of 595 to 395 Feet................................................................................63

Stream Altitudes of 395 to 360 Feet................................................................................63

Stream Altitudes of 360 to 220 Feet................................................................................63

Stream Altitudes of 220 to 35 Feet..................................................................................64

Waikapu ̄ Stream ........................................................................................................................64

Stream Altitudes of 1,160 to 1,080 Feet..........................................................................64

Stream Altitudes of 1,080 to 950 Feet.............................................................................64

Stream Altitudes of 950 to 820 Feet................................................................................64

Stream Altitudes of 820 to 560 Feet................................................................................64

Stream Altitudes of 560 to 400 Feet................................................................................66

Stream Altitudes of 400 to 40 Feet..................................................................................66
 ix

Stream Altitudes of 40 to 20 Feet....................................................................................67

Stream Altitudes of 20 to 10 Feet....................................................................................67

Natural, Undiverted Flow Characteristics at Ungaged Sites ......................................................67

Waiheÿe River .............................................................................................................................73

Waiehu Stream...........................................................................................................................73

ÿĪao Stream..................................................................................................................................74

Waikapu ̄ Stream.........................................................................................................................74

Maintaining Continuous Flows to the Ocean .................................................................................74

Waiheÿe River .............................................................................................................................74

Waiehu Stream...........................................................................................................................74

ÿĪao Stream..................................................................................................................................77

Waikapu ̄ Stream.........................................................................................................................77

Recent Diverted Low-Flow Characteristics in Streams ........................................................................77

Low-Flow Partial-Record Stations...................................................................................................77

Flow Characterization from Mounted Cameras.............................................................................79

Waiheÿe River .............................................................................................................................79

Waiehu Stream...........................................................................................................................79

ÿĪao Stream..................................................................................................................................79

Waikapu ̄ Stream.........................................................................................................................79

Effects of Surface-Water Diversions on Streamflow ............................................................................80

Waiheÿe River ......................................................................................................................................80

Waiehu Stream....................................................................................................................................81

ÿĪao Stream...........................................................................................................................................84

Waikapu ̄ Stream..................................................................................................................................85

Ditch-Flow Relations ...................................................................................................................................87

Waiheÿe River ......................................................................................................................................87

Waiehu Stream....................................................................................................................................89

ÿĪao Stream...........................................................................................................................................90

Waikapu ̄ Stream..................................................................................................................................91

Effects of Surface-Water Diversions on Recharge................................................................................91

Waiheÿe River ......................................................................................................................................92

Waiehu Stream....................................................................................................................................93

ÿĪao Stream...........................................................................................................................................93

Waikapu ̄ Stream..................................................................................................................................97

Effects of Surface-Water Diversions on Physical Habitat....................................................................97

Stream Habitat Data Collection........................................................................................................99

Study Reaches ...........................................................................................................................99

Cross Sections............................................................................................................................99

Quantification of Suitable Habitat....................................................................................................99

Reduction of Habitat Caused by Diversions.................................................................................105

Waiheÿe River ...........................................................................................................................107

Waiehu Stream.........................................................................................................................107

ÿĪao Stream................................................................................................................................107

Waikapu ̄ Stream.......................................................................................................................111
x

Effects of Surface-Water Diversions on Water Temperature............................................................113

Daily Mean Temperatures ...............................................................................................................114

Waiheÿe River ...........................................................................................................................119

South Waiehu Stream.............................................................................................................119

ÿĪao Stream................................................................................................................................120

Waikapu ̄ Stream.......................................................................................................................122

Diurnal Temperature Variations......................................................................................................123

Waiheÿe River ...........................................................................................................................123

South Waiehu Stream.............................................................................................................123

ÿĪao Stream................................................................................................................................123

Waikapu ̄ Stream.......................................................................................................................125

Summary......................................................................................................................................................129

References Cited........................................................................................................................................131

Appendix A. Surface-Water Diversions.................................................................................................137

Waiheÿe River ....................................................................................................................................137

Waiehu Stream..................................................................................................................................137

ÿĪao Stream.........................................................................................................................................140

Waikapu ̄ Stream................................................................................................................................143

Appendix B. Miscellaneous Discharge Measurements During 2004–2009, 

 Na ̄ Wai ÿEha ̄, Maui, Hawaiÿi .................................................................................................................146

Figures

ES1. Streams, diversion intakes, and major ditch systems, Na ̄ Wai ÿEha ̄ area, Maui, 

 Hawaiÿi..................................................................................................................................................iv

ES2. Photograph of a typical diversion intake that commonly stretches across the entire 

 low-flow channel of a stream (Reservoir 6 intake on Waikapu ̄ Stream, Maui, 

 Hawaiÿi, March 17, 2005) ....................................................................................................................v

ES3. Photograph of dry streambed caused by upstream diversions, ÿĪao Stream, Maui, 

 Hawaiÿi (September 22, 2006).............................................................................................................v

ES4. Generalized relation between habitat and discharge for ÿoÿopu ÿalamoÿo, ÿoÿopu 

 no ̄pili, ÿoÿopu na ̄kea, ÿo ̄paekalaÿole, and hïhïwai in Waiheÿe River and Waiehu, 

 ÿĪao, and Waikapu ̄ Streams, Maui, Hawaiÿi.....................................................................................vi

 1. Na ̄ Wai ÿEha ̄ study area, Maui, Hawaiÿi.............................................................................................3 

 2. Photograph of taro being cultivated near Waiheÿe River, Maui, Hawaiÿi

 (June 8, 2006)........................................................................................................................................4

 3. Photograph of ÿĪao Stream channel near an altitude of 160 feet, Maui, Hawaiÿi, during

 diverted conditions on June 6, 2006..................................................................................................4

 4. Mean monthly rainfall at selected rain-gaging stations, Maui, Hawaiÿi.....................................8

 5. Generalized geology, central Maui, Hawaiÿi....................................................................................9

 6. Photographs of cobble beach near the mouths of selected streams, Maui, 

 Hawaiÿi .................................................................................................................................................10 

 7. Ditch systems, stream-gaging stations, and selected rain-gaging stations, 

 Na ̄ Wai ÿEha ̄ area, Maui, Hawaiÿi......................................................................................................12

 8. Conceptual diagram showing relation between surface water and groundwater 

 within the drainage basin of a stream............................................................................................15
 xi

9. Distribution of ÿoÿopu ÿalamoÿo (Lentipes concolor, shown in inset photograph) 

 from stream surveys during August and September 2008, Na ̄ Wai ÿEha ̄, Maui, 

 Hawaiÿi...............................................................................................................................................23

 10. Distribution of ÿoÿopu no ̄pili (Sicyopterus stimpsoni, shown in inset photograph) 

 from stream surveys during August and September 2008, Na ̄ Wai ÿEha ̄, Maui, 

 Hawaiÿi...............................................................................................................................................24

 11. Distribution of ÿoÿopu na ̄kea (Awaous guamensis, shown in inset photograph) 

 from stream surveys during August and September 2008, Na ̄ Wai ÿEha ̄, Maui, 

 Hawaiÿi...............................................................................................................................................25

 12. Distribution of ÿo ̄paekalaÿole (Atyoida bisulcata, shown in inset photograph) 

 from stream surveys during August and September 2008, Na ̄ Wai ÿEha ̄, Maui, 

 Hawaiÿi...............................................................................................................................................26

 13. Selected native stream fauna, including ÿoÿopu ÿakupa (Eleotris sandwicensis, 

 shown in upper inset photograph), a ̄holehole (Kuhlia xenura, shown in lower 

 inset photograph), and unidentified ÿoÿopu, observed during 2008, Na ̄ Wai ÿEha ̄, 

 Maui, Hawaiÿi....................................................................................................................................27

 14. Distribution of Tahitian prawn (Macrobrachium lar, shown in upper inset photo-

 graph) and crayfish (Procambarus clarkii, shown in lower inset photograph) 

 from stream surveys during August and September 2008, Na ̄ Wai ÿEha ̄, Maui, 

 Hawaiÿi...............................................................................................................................................28

 15. Distribution of green swordtails (Xiphophorus helleri, shown in upper inset 

 photograph) and guppies (Poecilia reticulata, shown in lower inset photograph) 

 from stream surveys during August and September 2008, Na ̄ Wai ÿEha ̄, Maui, 

 Hawaiÿi...............................................................................................................................................29

 16. Photographs of isolated shallow pool of water with ÿoÿopu near an altitude of 

 20 feet, Waiehu Stream, Maui, Hawaiÿi........................................................................................32

 17. Photograph of dam structure just downstream of the Spreckels Ditch diversion 

 intake near an altitude of 270 feet, South Waiehu Stream, Maui, Hawaiÿi 

 (July 17, 2006)................................................................................................................................... 32

 18. Photograph of vertical drop structure in concrete-lined channel near an altitude 

 of 220 feet, ÿI ̄ao Stream, Maui, Hawaiÿi (August 13, 2008).........................................................33

 19. Photograph of concrete-lined channel of ÿI ̄ao Stream near an altitude of 30 feet, 

 Maui, Hawaiÿi................................................................................................................................... 33

 20. Photograph of subvertical drop near an altitude of 370 feet, ÿI ̄ao Stream, Maui, 

 Hawaiÿi (June 6, 2006)..................................................................................................................... 34

 21. Discharge-, temperature-, and habitat-measurement sites, mounted-camera sites, 

 and photographed sites, Waiheÿe River, Maui, Hawaiÿi............................................................ 37

 22. Discharge-, temperature-, and habitat-measurement sites, mounted-camera sites, 

 and photographed sites, Waiehu Stream, Maui, Hawaiÿi........................................................ .38

 23. Discharge-, temperature-, and habitat-measurement sites, mounted-camera sites, 

 and photographed sites, ÿI ̄ao Stream, Maui, Hawaiÿi................................................................ 39

 24. Discharge-, temperature-, and habitat-measurement sites, mounted-camera sites, 

 and photographed sites, Waikapu ̄ Stream, Maui, Hawaiÿi........................................................40

 25. Annual flow statistics (climate years 1984–2007) for Waiheÿe River and ÿI ̄ao 

 Stream, Maui, Hawaiÿi..................................................................................................................... 41

 26. Monthly flow statistics (climate years 1984–2007) for Waiheÿe River and ÿI ̄ao Stream,

 Maui, Hawaiÿi....................................................................................................................................42

 27. Flow-duration curves for early historical period and climate years 1984–2007, 

 Waiheÿe River and ÿI ̄ao Stream, Maui, Hawaiÿi...........................................................................43
xii

28. Time lines of available data from selected gaging stations (numbers on lines) 

during 1910–17, Maui, Hawaiÿi......................................................................................................... 44

29. Relation between concurrent duration discharges for North Waiehu Stream and 

index stations during the period 1912–15, and selected duration discharges 

for North Waiehu Stream and index stations during the 1984–2007 base period, 

Maui, Hawaiÿi......................................................................................................................................48

30. Relation between concurrent duration discharges for South Waiehu Stream and 

index stations during the period 1911–17, and selected duration discharges for 

South Waiehu Stream and index stations during the 1984–2007 base period, Maui, 

Hawaiÿi................................................................................................................................................. 49

31. Relation between concurrent duration discharges for Waikapu ̄ Stream and index 

stations during the period 1911–17, and selected duration discharges for Waikapu ̄

Stream and index stations during the 1984–2007 base period, Maui, Hawaiÿi.........................50

32. Seepage-run measurements over selected reaches, Waiheÿe River, Maui, Hawaiÿi.............54

33. Seepage-run measurements over selected reaches, Waiehu Stream, Maui, 

Hawaiÿi..................................................................................................................................................55

34. Seepage-run measurements over selected reaches, ÿĪao Stream, Maui, Hawaiÿi................. 56

35. Seepage-run measurements over selected reaches, Waikapu ̄ Stream, Maui, 

Hawaiÿi..................................................................................................................................................57

36. Relation between undiverted streamflows at an upstream and downstream site, 

Waiehu Stream, Maui, Hawaiÿi........................................................................................................ 60

37. Relation between undiverted streamflows at an upstream and downstream site, 

ÿĪao Stream, Maui, Hawaiÿi................................................................................................................65

38. Relation between discharge from the Mokuhau Spring and discharge at streamgaging station 16604500, ÿĪao Stream, Maui, Hawaiÿi................................................................... 66

39. Relation between undiverted streamflows at an upstream and downstream site, 

Waikapu ̄ Stream, Maui, Hawaiÿi.......................................................................................................68

40. Relation between discharge near an altitude of 605 feet and discharge near an 

altitude of 45 feet for natural, undiverted conditions, Waiheÿe River, Maui, Hawaiÿi............. 75

41. Relation between discharge near an altitude of 880 feet in North Waiehu Stream 

and discharge near an altitude of 20 feet in Waiehu Stream for natural, undiverted 

conditions, Maui, Hawaiÿi................................................................................................................. 75

42. Relation between discharge near an altitude of 780 feet and discharge near an 

altitude of 35 feet for natural, undiverted conditions, ÿĪao Stream, Maui, Hawaiÿi..................76

43. Relation between discharge near an altitude of 1,160 feet and discharge near an 

altitude of 10 feet for natural, undiverted conditions, Waikapu ̄ Stream, Maui, Hawaiÿi.........76

44. Photographs of overflowing flumes discharging water originating from one stream 

into another stream, Maui, Hawaiÿi.................................................................................................78

45. Photographs of diverted water being returned to streams during periods of ditch 

maintenance, Maui, Hawaiÿi.............................................................................................................78

46. Photograph of partially covered (with blue tarp) diversion intake common to the

ÿĪao-Ma ̄niania and ÿĪao-Waikapu ̄ Ditches near an altitude of 780 feet, ÿĪao 

Stream, Maui, Hawaiÿi (July 30, 2007)............................................................................................. 79
 xiii

47. Estimated discharges (Q50, Q70, and Q90) in Waiheÿe River, Maui, Hawaiÿi, resulting 

from diversions into the Waiheÿe Ditch and Spreckels Ditch with indicated 

hypothetical intake capacities.........................................................................................................81

48. Estimated discharges (Q50, Q70, and Q90) in Waiheÿe River near an altitude of 45 feet, 

Maui, Hawaiÿi, resulting from diversions into the Waiheÿe Ditch and Spreckels 

Ditch with indicated hypothetical intake capacities....................................................................82

49. Estimated discharges (Q50, Q70, and Q90) in Waiehu Stream near an altitude of 

190 feet, Maui, Hawaiÿi, resulting from diversions into the North Waiehu Ditch 

and Spreckels Ditch with indicated hypothetical intake capacities.........................................83

50. Estimated discharges (Q50, Q70, and Q90) in Waiehu Stream near an altitude of 20 

feet, Maui, Hawaiÿi, resulting from diversions into the North Waiehu Ditch and 

Spreckels Ditch with indicated hypothetical intake capacities.................................................84

51. Estimated discharges (Q50, Q70, and Q90) in ÿĪao Stream near an altitude of 220 feet, 

Maui, Hawaiÿi, resulting from diversions into the ÿĪao-Ma ̄niania and ÿĪao-Waikapu ̄

Ditches and Spreckels Ditch with indicated hypothetical intake capacites........................... 85 

52. Estimated discharges (Q50, Q70, and Q90) in ÿĪao Stream near an altitude of 35 feet, 

Maui, Hawaiÿi, resulting from diversions into the ÿĪao-Ma ̄niania and ÿĪao-Waikapu ̄

Ditches and Spreckels Ditch with indicated hypothetical intake capacites........................... 86

53. Estimated discharges (Q50, Q70, and Q90) in Waikapu ̄ Stream near an altitude of 

400 feet, Maui, Hawaiÿi, resulting from diversion into the South Side Ditch and 

combined diversions into a private ÿauwai (ditch) near an altitude of 560 feet, 

Waiheÿe Ditch, and Reservoir 6 Ditch with indicated hypothetical intake 

capacities............................................................................................................................................ 87

54. Estimated diversion discharges (Q50, Q70, and Q90) for the Waiheÿe Ditch and 

Spreckels Ditch, Waiheÿe River, Maui, Hawaiÿi, for indicated intake capacities.................... 88

55. Estimated diversion discharges (Q50, Q70, and Q90) for the North Waiehu Ditch, 

North Waiehu Stream, and Spreckels Ditch, South Waiehu Stream, Maui, 

Hawaiÿi, for indicated intake capacities.........................................................................................89

56. Estimated diversion discharges (Q50, Q70, and Q90) for the Spreckels Ditch, ÿĪao 

Stream, Maui, Hawaiÿi, for indicated intake capacities.............................................................. 90

57. Estimated combined diversion discharges (Q50, Q70, and Q90) for a private ÿauwai 

(ditch) near an altitude of 560 feet, Waiheÿe Ditch, and Reservoir 6 Ditch, Waikapu ̄

Stream, Maui, Hawaiÿi, for indicated intake capacities...............................................................92 

58. Reduction in potential groundwater recharge, relative to undiverted conditions, 

 caused by diversions into the Waiheÿe Ditch and Spreckels Ditch with 

 indicated intake capacities, Waiheÿe River, Maui, Hawaiÿi ........................................................94

59. Reduction in potential groundwater recharge, relative to undiverted conditions, 

 caused by diversions into the North Waiehu and Spreckels Ditches with 

 indicated intake capacities, Waiehu Stream, Maui, Hawaiÿi .....................................................95

60. Reduction in potential groundwater recharge, relative to undiverted conditions, 

 caused by diversions into the ÿĪao-Ma ̄niania and ÿĪao-Waikapu ̄ Ditches and 

 Spreckels Ditch with indicated intake capacities, ÿĪao Stream, Maui, Hawaiÿi ......................96
xiv

61. Reduction in potential groundwater recharge, relative to undiverted conditions, 

 caused by diversion into the South Side Ditch and combined diversions into a 

 private ÿauwai (ditch) near an altitude of 560 feet, Waiheÿe Ditch, and Reservoir 

 6 Ditch with indicated intake capacities, Waikapu ̄ Stream, Maui, Hawaiÿi..........................98

62. Froude number suitability curves for selected native stream fauna, Maui, 

 Hawaiÿi............................................................................................................................................102

63. Depth suitability curves for selected native stream fauna, Maui, Hawaiÿi ........................103

64. Relations between habitat (weighted usable area) for selected native species 

 and discharge in Waiheÿe River, Maui, Hawaiÿi.......................................................................104

65. Relations between habitat (weighted usable area) for selected native species 

and discharge in Waiehu Stream, Maui, Hawaiÿi ...................................................................108

66. Relations between habitat (weighted usable area) for selected native species 

and discharge in ÿĪao Stream, Maui, Hawaiÿi...........................................................................110

67. Relations between habitat (weighted usable area) for selected native species 

and discharge in Waikapu ̄ Stream, Maui, Hawaiÿi .................................................................112

68. Generalized relation between habitat and discharge for ÿoÿopu ÿalamoÿo, ÿoÿopu

no ̄pili, ÿoÿopu na ̄kea, ÿopaekalaÿole, and hïhïwai in Waiheÿe River and Waiehu, 

ÿĪao, and Waikapu ̄ Streams, Maui, Hawaiÿi..............................................................................114

69. Reduction in physical habitat (average weighted usable area), relative to 

undiverted conditions, caused by diversions into the Waiheÿe Ditch and 

Spreckels Ditch with indicated intake capacities, Waiheÿe River near an 

altitude of 45 feet, Maui, Hawaiÿi ...............................................................................................115

70. Reduction in physical habitat (average weighted usable area), relative to 

undiverted conditions, caused by diversions into the North Waiehu and 

Spreckels Ditches with indicated intake capacities, Waiehu Stream near 

an altitude of 20 feet, Maui, Hawaiÿi..........................................................................................116

71. Reduction in physical habitat (average weighted usable area), relative to 

undiverted conditions, caused by diversions into the ÿĪao-Ma ̄niania and 

ÿĪao-Waikapu ̄ Ditches and Spreckels Ditch with indicated intake capacities, 

ÿĪao Stream near an altitude of 35 feet, Maui, Hawaiÿi...........................................................117

72. Reduction in physical habitat (average weighted usable area), relative to 

undiverted conditions, caused by diversion into the South Side Ditch and 

combined diversions from a private ÿauwai (ditch) near an altitude of 560 feet, 

Waiheÿe Ditch, and Reservoir 6 Ditch with indicated intake capacities, Waikapu ̄ 

Stream near an altitude of 400 feet, Maui, Hawaiÿi ................................................................118

73. Daily mean discharge and water temperatures, Waiheÿe River, Maui, Hawaiÿi................121 

74. Daily mean water temperatures between altitudes of 635 and 190 feet, South 

Waiehu Stream, Maui, Hawaiÿi ..................................................................................................122

75. Daily mean discharge and water temperatures, ÿĪao Stream, Maui, Hawaiÿi ....................124

76. Daily mean water temperatures between altitudes of 1,160 and 560 feet, 

Waikapu ̄ Stream, Maui, Hawaiÿi.................................................................................................125
 xv

77. Discharge and water temperatures during August and September, 2007, 

Waiheÿe River, Maui, Hawaiÿi .....................................................................................................126

78. Water temperatures during August and September, 2007, South Waiehu 

Stream, Maui, Hawaiÿi .................................................................................................................127

79. Discharge and water temperatures during August and September, 2007, ÿĪao 

Stream, Maui, Hawaiÿi .................................................................................................................128

80. Water temperatures during August and September, 2007, Waikapu ̄ Stream, 

Maui, Hawaiÿi ................................................................................................................................129

A1. Historical ditch systems, West Maui, Hawaiÿi.........................................................................138

A2. Photographs of Waiheÿe Ditch diversion intake near an altitude of 600 feet, 

Waiheÿe River, Maui, Hawaiÿi .....................................................................................................139

A3. Photographs of Spreckels Ditch diversion intake on the south side of Waiheÿe 

River near an altitude of 400 feet, Maui, Hawaiÿi ....................................................................139

A4. Photographs of dam structure for Spreckels Ditch diversion intake near an 

altitude of 400 feet, Waiheÿe River, Maui, Hawaiÿi ..................................................................140

A5. Photograph of Field 1 diversion intake (viewed from upstream side) near an 

altitude of 260 feet, Waiheÿe River, Maui, Hawaiÿi (June 8, 2006).........................................140

A6. Photographs of North Waiehu Ditch diversion intake near an altitude of 880 feet, 

North Waiehu Stream, Maui, Hawaiÿi .......................................................................................141

A7. Photographs of diversion intakes for private ÿauwai (ditches), South Waiehu 

Stream, Maui, Hawaiÿi .................................................................................................................141

A8. Photograph of Spreckels Ditch diversion intake on the south side of South 

Waiehu Stream near an altitude of 270 feet, Maui, Hawaiÿi (July 27, 2006)........................142

A9. Photograph of concrete remnants related to the diversion intake for the Kama 

Ditch near an altitude of 430 feet, ÿĪao Stream, Maui, Hawaiÿi (June 9, 2006)....................142

A10. Photographs of diversion intake common to the ÿĪao-Ma ̄niania and ÿĪaoWaikapu ̄ Ditches near an altitude of 780 feet, ÿĪao Stream, Maui, Hawaiÿi ........................142

A11. Photographs of Spreckels Ditch diversion intake on the south side of ÿĪao 

Stream near an altitude of 250 feet, Maui, Hawaiÿi ................................................................143

A12. Photographs of South Side Ditch diversion intake on the south side of Waikapu ̄

Stream near an altitude of 1,120 feet, Maui, Hawaiÿi .............................................................144

A13. Photographs of Everett Ditch diversion intake near an altitude of 900 feet, 

Waikapu ̄ Stream, Maui, Hawaiÿi (August 23, 2006).................................................................144

A14. Photograph of diversion intake for private ÿauwai (ditch) on the north side of

Waikapu ̄ Stream near an altitude of 560 feet, Maui, Hawaiÿi (June 9, 2006)......................145

A15. Photograph of diversion intake for Waiheÿe Ditch near an altitude of 440 feet, 

Waikapu ̄ Stream, Maui, Hawaiÿi (October 22, 2008)................................................................145

A16. Photograph of diversion intake for the Reservoir 6 Ditch near an altitude of 

410 feet, Waikapu ̄ Stream, Maui, Hawaiÿi (March 17, 2005)..................................................145
xvi

Tables

ES1. Surface-water diversion intakes, Na ̄ Wai ÿEha ̄, Maui, Hawaiÿi ...................................................v

1. Surface-water diversion intakes, Na ̄ Wai ÿEha ̄, Maui, Hawaiÿi ................................................. 13

2. Water-development tunnels, N ̄a Wai ÿEha ̄, Maui, Hawaiÿi .........................................................14

3. Native aquatic species observed in Waiheÿe River from surveys during 1978–2008, 

 Maui, Hawaiÿi .................................................................................................................................... 17

4. Native aquatic species observed in Waiehu Stream from surveys during 1961–2008, 

 Maui, Hawaiÿi ................................................................................................................................ ....17

5. Native aquatic species observed in ÿĪao Stream from surveys during 1970–2008, 

 Maui, Hawaiÿi .................................................................................................................................... 18

6. Native aquatic species observed in Waikapu ̄ Stream from surveys during 

 1961–2008, Maui, Hawai‘i.................................................................................................................18

7. Non-native aquatic species observed in Waiheÿe River from surveys during 

 1978–2008, Maui, Hawaiÿi.................................................................................................................20

8. Non-native aquatic species observed in Waiehu Stream from surveys during 

 1961–2008, Maui, Hawaiÿi.................................................................................................................20

9. Non-native aquatic species observed in ÿĪao Stream from surveys during 

 1961–2008, Maui, Hawaiÿi................................................................................................................. 21

 10. Non-native aquatic species observed in Waikapu ̄ Stream from surveys during 

 1961–2008, Maui, Hawaiÿi................................................................................................................. 21

 11. Selected active and historical U.S. Geological Survey (USGS) gaging stations 

 in and near the Na ̄ Wai ÿEha ̄ area, Maui, Hawaiÿi ........................................................................36

 12. U.S. Geological Survey miscellaneous discharge measurements during 2004–2009, 

 sorted by Na ̄ Wai ÿEh ̄a stream and from upstream to downstream, Maui, Hawaiÿi 

 (in appendix B).................................................................................................................................146

 13. Selected duration discharges (natural, undiverted conditions) for Waiheÿe River 

 and ÿĪao, Honoko ̄hau, and Honopou Streams during climate years 1984–2007, 

 Maui, Hawaiÿi..................................................................................................................................... 44

 14. Concurrent periods used for extension of records from North Waiehu, South 

 Waiehu, and Waikapu ̄ Streams, West Maui, Hawaiÿi................................................................. 47

 15. Selected duration discharges (natural, undiverted conditions) estimated for 

 North Waiehu Stream near an altitude of 880 feet during climate years 1984–2007, 

 Maui, Hawaiÿi......................................................................................................................................51

 16. Selected duration discharges (natural, undiverted conditions) estimated for 

 South Waiehu Stream near an altitude of 870 feet during climate years 1984–2007, 

 Maui, Hawaiÿi......................................................................................................................................51

 17. Selected duration discharges (natural, undiverted conditions) estimated for 

 Waikapu ̄ Stream near an altitude of 880 feet during climate years 1984–2007, 

 Maui, Hawaiÿi..................................................................................................................................... 52

 18. Selected duration discharges (natural, undiverted conditions) for Waiheÿe River 

 during climate years 1984–2007, Maui, Hawaiÿi........................................................................... 69

 19. Selected duration discharges (natural, undiverted conditions) for Waiehu Stream 

 during climate years 1984–2007, Maui, Hawaiÿi........................................................................... 70

 20. Selected duration discharges (natural, undiverted conditions) for ÿĪao Stream 

 during climate years 1984–2007, Maui, Hawaiÿi............................................................................71

 21. Selected duration discharges (natural, undiverted conditions) for Waikapu ̄ Stream

 during climate years 1984–2007, Maui, Hawaiÿi........................................................................... 72

 
 xvii

Conversion Factors 

Inch/Pound to SI

Multiply By To obtain 

Length 

Area

Volume

Flow rate

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 mean sea level. 

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD83). 

Altitude, as used in this report, refers to distance above the vertical datum. 

22. Percentage of riffle, run, and pool habitat within studied stream reaches, 

 Maui, Hawaiÿi ...................................................................................................................................100

23. Substrate size categories and dominant substrate suitability values for 

 selected native species..................................................................................................................101

24. Temperature-monitoring sites, Na ̄ Wai ÿEh ̄a, Maui, Hawaiÿi.....................................................120

Abstract

The perennial flow provided by Waihe‘e River, Waiehu 

Stream, ‘Īao Stream, and Waikapū Stream, collectively known 

as Nā Wai ‘Ehā (“The Four Streams”), made it possible for 

widespread agricultural activities to flourish in the eastern 

part of West Maui, Hawai‘i. The streams of the Nā Wai 

‘Ehā area flow in their upper reaches even during extended 

dry-weather conditions because of persistent groundwater 

discharge to the streams. Overall, the lower reaches of these 

streams lose water, which may contribute to groundwater 

recharge. 

During climate years 1984–2007 (when complete 

streamflow records were available for Waihe‘e River and ‘Īao 

Stream), Waihe‘e River had the greatest median flow of the 

four streams upstream of the uppermost diversion on each 

stream. The median flows, in million gallons per day, during 

climate years 1984–2007 were: 34 for Waihe‘e River near 

an altitude of 605 feet; 25 for ‘Īao Stream near an altitude of 

780 feet; and estimated to be 4.3 for Waikapū Stream near 

an altitude of 1,160 feet; 3.2 for North Waiehu Stream near 

an altitude of 880 feet; and 3.2 for South Waiehu Stream 

near an altitude of 870 feet. Existing stream diversions in the 

Nā Wai ‘Ehā area have a combined capacity exceeding at 

least 75 million gallons per day and are capable of diverting 

all or nearly all of the dry-weather flows of these streams, 

leaving some downstream reaches dry. Hourly photographs 

collected during 2006–2008 indicate that some stream reaches 

downstream of diversions are dry more than 50 percent of 

the time. Many of these reaches would be perennial or nearly 

perennial in the absence of diversions. 

A lack of sufficient streamflow downstream of 

existing diversions has led to recent conflicts between those 

currently diverting or using the water and those desiring 

sufficient instream flows for protection of traditional and 

customary Hawaiian rights (including the cultivation of 

taro), maintenance of habitat for native stream fauna, 

recreation, aesthetics, and groundwater recharge from loss 

of water through the streambed. In response to a need for 

additional information, the U.S. Geological Survey (USGS) 

undertook the present investigation to characterize the effects 

of existing surface-water diversions on (1) streamflow, (2) 

potential groundwater recharge from the streams to the 

underlying groundwater body, (3) physical habitat for native 

stream fauna (fish, shrimp, and snails), and (4) instream 

temperatures.

Information collected for this study includes discharge 

measurements under different streamflow conditions 

to characterize streamflow and seepage losses, hourly 

photographs of stream conditions from mounted cameras, 

snorkel surveys of stream fauna, measurements of 

microhabitat (depth, velocity, and substrate) under different 

flow conditions, and measurements of water temperatures. 

Families of curves were developed to show the relations 

between surface-water diversion intake capacity (the 

maximum rate that an intake can divert) and (1) selected 

duration discharges for sites near the coast; (2) selected 

duration discharges for the diversions; (3) groundwaterrecharge reduction; and (4) physical-habitat reduction for 

native stream fauna. These curves may be used by water 

managers to evaluate the effects of different diversion intake 

capacities on streamflow, water available for offstream use, 

groundwater recharge, and habitat for native stream fauna. 

Results of this study indicate the following:

1. If no water had been diverted from the Nā Wai 

‘Ehā streams during climate years 1984–2007, 

Waihe‘e River and ‘Īao Stream would have flowed 

continuously to the coast; Waiehu Stream would 

have flowed continuously to the coast at least 95 

percent of the time; and Waikapū Stream would have 

flowed continuously to the coast less than half of the 

time. 

2. The minimum flows upstream of the uppermost 

diversion in each stream necessary to maintain 

continuous flow near the coast, assuming no 

downstream diversions, are: 1 million gallons per 

day for Waihe‘e River; 1.3 million gallons per day 

for North Waiehu Stream and 1.1 million gallons per 

day for South Waiehu Stream; 5.2 million gallons 

per day for ‘Īao Stream; and 6.8 million gallons per 

day for Waikapū Stream. 

3. For main diversions in their current (2009) 

configurations (ignoring the smaller private ‘auwai, 

or ditches, and assuming none of the diverted 

water is returned to streams), estimated median 

streamflows are zero for Waihe‘e River near an 

altitude of 45 feet, ‘Īao Stream near an altitude of 

35 feet, and Waikapū Stream near an altitude of 400 

Effects of Surface-Water Diversion on Streamflow, 

Recharge, Physical Habitat, and Temperature, 

Na ̄ Wai ‘Eha ̄, Maui, Hawai‘i

By Delwyn S. Oki, Reuben H. Wolff, and Jeff A. Perreault
feet, and about a third of the natural, undiverted 

value for Waiehu Stream near an altitude of 20 feet. 

4. For natural, undiverted low-flow conditions (when 

flow is less than or equal to the median flow) the 

estimated average seepage loss (representing potential 

groundwater recharge) from each stream, downstream 

of the uppermost diversion, is: 1.7 million gallons per 

day for Waihe‘e River; 2.9 million gallons per day 

for North Waiehu Stream, South Waiehu Stream, and 

Waiehu Stream; 5.6 million gallons per day for ‘Īao 

Stream; and 4.3 million gallons per day for Waikapū 

Stream. 

5. For low-flow conditions and main diversions in their 

current (2009) configurations (ignoring the smaller 

private ‘auwai and assuming none of the diverted 

water is returned to streams), surface-water diversions 

reduce potential groundwater recharge in stream 

channels by: 1.7 million gallons per day for Waihe‘e 

River; 1 million gallons per day for North Waiehu 

Stream, South Waiehu Stream, and Waiehu Stream; 

4.8 million gallons per day for ‘Īao Stream; and 4 

million gallons per day for Waikapū Stream. 

6. Snorkel surveys conducted during 2008 identified 

the presence of native fauna in each of the Nā Wai 

‘Ehā streams. Native fauna observed in the Nā Wai 

‘Ehā streams include the endemic mountain shrimp, 

‘ōpaekala‘ole (Atyoida bisulcata); endemic gobies, 

‘o‘opu ‘alamo‘o (Lentipes concolor) and ‘o‘opu nōpili 

(Sicyopterus stimpsoni); the indigenous goby, ‘o‘opu 

nākea (Awaous guamensis); and an endemic eleotrid, 

‘o‘opu ‘akupa (Eleotris sandwicensis). 

7. In general, data indicate that physical habitat increases 

monotonically with discharge up to the median 

natural discharge. Thus, diversion of surface water 

from a stream reduces the amount of physical habitat 

available during low-flow conditions. A generalized 

relation between physical habitat and discharge was 

developed for this study. 

8. For low-flow conditions and main diversions in their 

current (2009) configurations (ignoring the smaller 

private ‘auwai and assuming none of the diverted 

water is returned to streams), surface-water diversions 

reduce physical habitat for native stream fauna by: 

100 percent for Waihe‘e River near an altitude of 45 

feet; more than 60 percent for Waiehu Stream near an 

altitude of 20 feet; 100 percent for ‘Īao Stream near 

an altitude of 35 feet; and more than 90 percent for 

Waikapū Stream near an altitude of 400 feet. 

9. During September 2006 to October 2007, when water 

temperatures were measured for this study, daily 

maximum temperatures did not exceed 27°C and daily 

minimum temperatures did not drop below 15°C at 

any of the study sites. At all of the study sites, daily 

maximum temperatures remained below the upperlethal-temperature limits for native aquatic species, 

as well as below the temperature that favors Pythium 

rot of taro, although water temperatures were not 

measured in reaches that commonly had zero flow. 

Introduction

The eastern part of West Maui, Hawai‘i, mainly is 

drained by Waihe‘e River, Waiehu Stream, ‘Īao Stream, and 

Waikapū Stream (fig. 1), collectively known as Nā Wai ‘Ehā 

or “The Four Streams” (Handy and Handy, 1991). (‘Īao 

Stream is sometimes referred to as Wailuku Stream, but for the 

purposes of this report it will be referred to as ‘Īao Stream.) 

The headwaters of Waihe‘e River and ‘Īao Stream extend 

to or near the summit of the West Maui Mountain at Pu‘u 

Kukui, where mean annual rainfall exceeds 350 in. Waihe‘e 

River and ‘Īao Stream are among the largest streams, in terms 

of streamflow, on Maui. North and South Waiehu Streams 

join near an altitude of about 220 ft to form Waiehu Stream. 

The headwaters of North and South Waiehu Streams are cut 

off from the summit area of the West Maui Mountain by the 

valleys of Waihe‘e River to the north and ‘Īao Stream to the 

south. Waikapū Stream is the only Nā Wai ‘Ehā stream that 

drains to the southern coast of Maui. The headwater area of 

Waikapū Stream is truncated by the valleys of ‘Īao Stream to 

the north and Olowalu Stream to the west. 

In the upper reaches where the stream channels intersect 

the groundwater body, groundwater discharge contributes 

to streamflow. Groundwater discharge to the streams of the 

Nā Wai ‘Ehā area creates flow in the upper reaches even 

during extended dry-weather conditions. The dependable flow 

of water provided by Waihe‘e River, Waiehu Stream, ‘Īao 

Stream, and Waikapū Stream made it possible for widespread 

agricultural activities to flourish in the Nā Wai ‘Ehā area. The 

lower reaches of the streams generally lose water because of 

infiltration into the streambed, and this loss may contribute to 

groundwater recharge of the underlying aquifer. 

Surface water in the Nā Wai ‘Ehā area traditionally 

supported large areas of kalo (taro) cultivation by Native 

Hawaiians. The area between the valleys of Waihe‘e River 

and ‘Īao Stream was at one time the largest area of wetlandtaro cultivation in the Hawaiian Islands (Handy and Handy, 

1991). Taro currently (2009) is cultivated in the Nā Wai ‘Ehā 

area for commercial and individual purposes (fig. 2), although 

to a much lesser extent than in the past. Starting in the 19th 

century, large-scale sugarcane plantations began to dominate 

the landscape at altitudes mainly below about 600 feet in the 

Nā Wai ‘Ehā area. Surface water was diverted from streams to 

meet irrigation needs for sugarcane cultivation (Wilcox, 1996; 

Yamanaga and Huxel, 1970). Yamanaga and Huxel (1970) 

indicated that an average of about 67 million gallons per day 

(Mgal/d) was diverted, mainly for sugarcane irrigation, from 

Waihe‘e River, Waiehu Stream, ‘Īao Stream, and Waikapū 

Stream. (Discharge is measured by the U.S. Geological Survey 

[USGS] in terms of cubic feet per second [ft3

/s], and all 

2 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Figure 1. Na ̄ Wai ÿEha ̄ study area, Maui, Hawaiÿi.

15

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Wailuku District Lahaina District Wailuku District Makawao District

Makawao District

Häna District

Keälia Pond

rt S

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STUDY AREA LINE OF EQUAL MEAN ANNUAL RAINFALL, IN INCHES (modified from Giambelluca and others, 1986)JUDICIAL-DISTRICT BOUNDARYSTREAM-GAGING STATION AND NUMBER

60

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Base modified from U.S. Geological Survey National HydrographyDataset, 1:24,000 scale, Universal Transverse Mercator projection, zone 4, NAD83 datum.

22°20°

158° 156° 160°

Kauaÿi

Niÿihau

Oÿahu

Maui

Molokaÿi

Länaÿi

Kahoÿolawe

Hawaiÿi

HAWAIÿI

LOCATION MAP

PACIFIC OCEAN

Introduction 3
computations in this report were made in terms of ft3

/s. Where 

applicable, discharge values are reported in the original ft3/s 

units as well as the converted units of Mgal/d.) 

In 1987, about 53 percent of the diverted water from the 

Nā Wai ‘Ehā streams was used by Wailuku Sugar Company, 

35 percent by Hawaiian Sugar and Commercial Company 

(HC&S), 10 percent by small private users, and 2 percent 

by Maui County (Chumbley, 2007). In 1988, Wailuku Sugar 

Company, the main user of the diverted water, shut down 

operations in the Nā Wai ‘Ehā area (Dorrance and Morgan, 

2000), where it had been irrigating about 5,250 acres of 

sugarcane (Chumbley, 2007). Some of the land previously 

cultivated in sugarcane by Wailuku Sugar Company was 

later used for macadamia nuts and pineapples by Wailuku 

Agribusiness Company, Inc., or leased by HC&S for 

sugarcane. 

In 2005, about 79 percent of the diverted water from 

the Nā Wai ‘Ehā streams was used by HC&S, 10 percent 

by small private users, 4 percent by Maui County, and the 

remaining 7 percent was for various users with water delivery 

agreements with Wailuku Water Company, LLC (WWC) 

(Chumbley, 2007). (Predecessors to Wailuku Water Company, 

LLC, include Wailuku Agribusiness Company, Inc., Wailuku 

Sugar Company, and C. Brewer and Company, Limited.) As of 

2009, water continued to be diverted from streams in the Nā 

Wai ‘Ehā area for sugarcane irrigation in the central isthmus 

area by HC&S and for municipal and domestic uses, golfcourse and landscape irrigation, maintaining pastures for cattle 

grazing, and other agricultural uses. The main ditch systems 

currently are owned and maintained by WWC. HC&S assists 

in the maintenance of some of the ditch systems. 

Existing diversions are capable of diverting all or nearly 

all of the dry-weather flows of the Nā Wai ‘Ehā streams, which 

leaves some downstream reaches completely dry (fig. 3). A 

lack of sufficient water downstream of existing diversions has 

led to recent conflicts between those currently diverting or 

using the water and those desiring sufficient instream flows 

for protection of traditional and customary Hawaiian rights 

(including the cultivation of taro), maintenance of habitat for 

native stream fauna, recreation, and aesthetics. The County 

of Maui Department of Water Supply currently withdraws 

groundwater from the aquifers potentially recharged by 

these streams. Thus, an understanding of the effects of the 

diversions on streamflow characteristics and groundwater 

recharge is essential for proper planning and management 

of the resource. It is becoming increasingly apparent that 

competition exists for the limited surface-water resources in 

Hawai‘i, and this competition will likely play a role in future 

planning and management decisions. 

The State Water Code mandates that the State of 

Hawai‘i Commission on Water Resource Management 

(CWRM) establish a statewide instream use protection 

program (State Water Code, Hawai‘i Revised Statutes, 

chapter 174C, section 71). The main mechanism that the 

CWRM has for protection of instream uses is to establish 

instream flow standards that describe the flows necessary to 

protect the public interest in the particular stream in light 

of existing and potential water developments, including 

the economic effect of restriction of such use (State Water 

Code, Hawai‘i Revised Statutes, chapter 174C, section 71[1]

[C]). The CWRM has recognized certain instream uses as 

beneficial, including: (1) maintenance of fish and wildlife 

habitat, (2) outdoor recreational activities, (3) maintenance 

of ecosystems, such as estuaries, wetlands, and stream 

vegetation, (4) aesthetic values, such as waterfalls and 

scenic waterways, (5) maintenance of water quality, (6) the 

conveyance of irrigation and domestic water supplies to 

downstream points of diversion, and (7) the protection of 

traditional and customary Hawaiian rights.

Figure 2. Photograph of taro being cultivated near Waiheÿe River, Maui, Hawaiÿi 

(June 8, 2006).

Figure 2. Photograph of taro being cultivated near Waiheÿe 

River, Maui, Hawaiÿi (June 8, 2006).

downstream

direction

Figure 3. Photograph of ÿÏao Stream channel near an altitude of 160 feet, Maui, 

Hawaiÿi, during diverted conditions on June 6, 2006.

Figure 3. Photograph of ÿĪao Stream channel near an altitude of 160 feet, Maui, Hawaiÿi, during diverted conditions 

on June 6, 2006.

4 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
On October 19, 1988, the CWRM set interim instream 

flow standards for all streams in West Maui. The interim 

instream flow standard was defined as “that amount of water 

flowing in each stream on the effective date of this standard, 

and as that flow may naturally vary throughout the year and 

from year to year without further amounts of water being 

diverted offstream through new or expanded diversions, and 

under the stream conditions existing on the effective date of 

the standard * * *” (Hawai‘i Administrative Rules, chapter 

169, section 13-169-48). The interim instream flow standards 

essentially allowed diversions existing at the time to continue 

operating unless a petition was filed with the CWRM to reduce 

diversions and restore water to the stream.

Since 1988, interim instream flow standards have 

been challenged as demand for water has increased and the 

ecological, cultural, and aesthetic significance of streams has 

become increasingly recognized. In June 2004, Earthjustice filed 

a petition with the CWRM, on behalf of Hui o Nā Wai ‘Ehā 

and Maui Tomorrow Foundation, Inc., to amend the interim 

instream flow standards for Waihe‘e River, Waiehu Stream, 

‘Īao Stream, and Waikapū Stream, and in December 2007 a 

contested-case hearing was initiated by the CWRM to address 

this issue. The results generated by the present cooperative 

study will help the CWRM to fulfill its obligation to determine 

technically defensible instream flow standards for the streams of 

Nā Wai ‘Ehā by providing scientific information addressing the 

hydrologic and aquatic-habitat aspects of the standards.

Purpose and Scope

In response to a need for additional information on the 

Nā Wai ‘Ehā streams, the U.S. Geological Survey (USGS) 

undertook the present investigation from 2006 to 2009 in 

cooperation with the County of Maui Office of Economic 

Development, County of Maui Department of Water Supply, 

State of Hawai‘i Commission on Water Resource Management, 

and State of Hawai‘i Office of Hawaiian Affairs. The objective 

of this study on Waihe‘e River, Waiehu Stream, ‘Īao Stream, 

and Waikapū Stream is to characterize the effects of existing 

surface-water diversions on (1) streamflow, (2) potential 

groundwater recharge from the streams to the underlying 

groundwater body, (3) physical habitat for native stream fauna 

(fish, shrimp, and snails), and (4) instream temperatures. 

This study does not predict the effects of flow restoration on 

native species abundance, nor does this study address water 

requirements for taro cultivation and aesthetic or recreational 

uses, algae and invertebrate food sources for native macrofauna, 

or reproduction of native species. 

Acknowledgments

This study was conducted in cooperation with the County 

of Maui Office of Economic Development, County of Maui 

Department of Water Supply, State of Hawai‘i Commission 

on Water Resource Management, and State of Hawai‘i Office 

of Hawaiian Affairs. Access to study sites was graciously 

provided by the following entities and individuals: Maui 

Coastal Land Trust (Dale Bonar and Scott Fisher), John 

Varel, Harry Apolo, and other residents along Waihe‘e River; 

Patricia Bragg, Stanley Izumigawa, and Paul Higashino for 

Waiehu Stream; John and Rose Duey, Nani Santos, Bob 

Horcajo, Vernon Lindsey, Tropical Gardens of Maui, Inc. 

(Bernie Graham), and the Hawai‘i Nature Center (J.D. Wyatt) 

for ‘Īao Stream; and David Niehaus, Noho‘ana Farm, LLC 

(Victor Pellegrino and Hōkūao Pellegrino), Ione Shimizu, 

Hawaiian Sugar and Commercial Company, and Maui Flavors 

Catering for Waikapū Stream. The Wailuku Water Company, 

LLC, also provided access to stream sites and their schedule 

of when water would be restored temporarily to streams 

during ditch-maintenance periods. We also benefitted much 

from discussions with the following individuals: Skippy Hau, 

Jonathan Kurtz, Megan Wells, Francis Cerizo, Zac and Val 

Kanoa, Duke Sevilla, David Ivy, and Frank Rocha and Kim 

Gaines. 

This study could not have been completed without 

assistance from the following U.S. Geological Survey 

personnel. Phillip C. Teeters, Matt A. Wong, and James W. 

Nelson maintained stream-gaging stations in Waihe‘e River 

and ‘Īao Stream. Sarah N. Rosa, Stephen B. Gingerich, Kolja 

Rotzoll, and Gordon Tribble assisted in making discharge 

measurements and other field activities. Tracy-Joy I. Saguibo 

processed temperature records and discharge measurements 

and interpreted photographs with the assistance of Craig A. 

Senter. John A. Engott assisted in stream reconnaissance at the 

onset of the study. 

Setting

The Island of Maui, the second largest of the Hawaiian 

Islands, occupies an area of 727.3 mi2

 (Juvik and Juvik, 1998) 

between latitudes 20°30 ́ and 21°05 ́ N. and between longitudes 

156°45 ́ and 155°55 ́ W. (fig. 1). The island is composed mainly 

of two shield volcanoes (Stearns and Macdonald, 1942): the 

older West Maui Volcano (West Maui Mountain), which rises 

to an altitude of 5,788 ft, and the younger East Maui Volcano 

(Haleakalā), which rises to an altitude of 10,023 ft. The interior 

parts of the West Maui Mountain are relatively rugged and 

steep in comparison to the gently sloping central saddle or 

isthmus that connects the East and West Maui Volcanoes. 

The central isthmus was formed by Haleakalā lava flows that 

banked up against and were deflected by the preexisting West 

Maui Mountain and were later buried by marine and terrestrial 

sedimentary deposits. The interior parts of West Maui Mountain 

are mainly forested conservation areas, the central isthmus 

mainly is used for agricultural purposes, and the coastal areas 

commonly are developed for residential or other urban uses. 

Setting 5
The Kahului and Wailuku areas of north-central Maui are the 

main population centers near the study area. 

The Nā Wai ‘Ehā study area includes the Waihe‘e River, 

and Waiehu, ‘Īao, and Waikapū Streams, which drain the eastern 

part of West Maui Mountain. These streams have eroded deep 

valleys that are incised to depths of a few thousand feet in places. 

The drainage basins of Waihe‘e River, Waiehu Stream, and 

‘Īao Stream, respectively, are 7.0, 4.7, and 11.4 mi2. Part of the 

southwestern slope of Haleakalā drains into the lowest reach of 

Waikapū Stream near Keālia Pond. Inland from Keālia Pond, and 

upstream of where the slopes of Haleakalā drain into Waikapū 

Stream, Waikapū Stream drains the West Maui Mountain only 

and this part of the drainage basin is about 6.9 mi2.

Land Use

Before the start of large-scale sugarcane plantation 

agriculture in the study area during the mid-19th century, the 

Nā Wai ‘Ehā area supported the largest continuous area of 

wetland-taro cultivation in the Hawaiian Islands (Handy and 

Handy, 1991). Native Hawaiians likely also cultivated sweet 

potatoes, dry-land taro, bananas, breadfruit, coconuts, and 

other subsistence, medicinal, ceremonial, ornamental, and 

utilitarian plants in the Nā Wai ‘Ehā area (see, for example, 

Handy and Handy, 1991; Kelly and others, 1978; Creed, 

1993). The earliest available population estimates for the 

Nā Wai ‘Ehā area were from the 1831–32 census (Schmitt, 

1973): the populations of Waihe‘e, Waiehu, ‘Īao (Wailuku), 

and Waikapū communities, respectively, were 827, 355, 2,256, 

and 733. Native Hawaiian populations may have been greater 

before western contact in the late 18th century, although 

precontact population estimates are uncertain (Schmitt, 1971). 

Sugarcane is not native to Hawai‘i, although it was 

introduced to Hawai‘i centuries before western contact. The 

following brief summary of sugarcane operations in the Nā 

Wai ‘Ehā area mainly is from Silva (1962) and Dorrance 

and Morgan (2000). The first sugar mill in the Nā Wai ‘Ehā 

area began operation in 1823, and King Kamehameha III 

built the King’s Mill sometime during 1839–40 in Wailuku. 

During 1839, about 80 acres were planted in sugarcane, 

presumably for processing by the King’s Mill, and in 1841 

Hung and Company produced sugar from its 150-acre 

plantation in Wailuku (Maclennan, 1995). During 1862 three 

sugarcane plantations (Waihe‘e, Wailuku, and Waikapū Sugar 

Companies) in the Nā Wai ‘Ehā area were formed, which 

marked the beginnings of large-scale commercial sugarcane 

operations in the area. Other sugarcane plantations in the Nā 

Wai ‘Ehā area included those of Bal and Adams, as well as 

E. Bailey and Son, both of which were sold to Wailuku Sugar 

Company in 1877. By 1879, Maclennan (1997) estimated that 

about 1,950 acres were planted in sugarcane in the Nā Wai 

‘Ehā area. In 1894, Wailuku Sugar Company purchased both 

Waihe‘e and Waikapū Sugar Companies, and total production 

was 4,349 tons of sugar. 

Maps showing generalized land use in the Nā Wai 

‘Ehā area are available for 1900, 1906, 1920, 1930, 1937, 

1956, 1975, 1976, 1982, 1980–84, 1985–89, 1990–99, 

2000–2004, 2001, and 2005 (Hawai‘i Territorial Planning 

Board, 1939; Coulter, 1940; Harland Bartholomew and 

Associates, 1957; Mitchell and others, 1977; U.S. Department 

of Agriculture, 1982; Engott and Vana, 2007; National 

Oceanic and Atmospheric Administration, 2001, 2005). 

Available land-use maps from 1930 and earlier indicate areas 

of wetland crops of taro and rice in addition to large areas 

of sugarcane cultivation in the Nā Wai ‘Ehā area. Before the 

1988 shutdown of sugarcane operations by Wailuku Sugar 

Company (Dorrance and Morgan, 2000), some of the land 

previously used for sugarcane cultivation in the Nā Wai ‘Ehā 

area was converted to macadamia nut orchards. Wailuku 

Agribusiness Company, Inc., irrigated about 1,580 acres of 

macadamia nuts with about 8 Mgal/d of water during the 

1980s and about 1,900 acres of pineapples with about 6 

Mgal/d during the early 1990s (Chumbley, 2007). By about 

2000, however, macadamia nuts and pineapples were no 

longer being actively cultivated on a large-scale commercial 

basis in the Nā Wai ‘Ehā area. 

Since 1900, land-use patterns on Maui have reflected 

increases in population and decreases in large-scale 

agricultural operations over time. The resident population on 

Maui increased from fewer than 28,000 in 1900 to 117,644 

in 2000 (State of Hawai‘i, 2007). In 2000, about 10 percent 

of the State’s population resided on Maui, and about 52 

percent of the residents on Maui were in the Wailuku District 

(fig. 1). Between 1980 and 2000, the resident population in 

the Wailuku District increased 91 percent, from 32,111 to 

61,346, which is consistent with the 87 percent increase of 

the resident population on Maui between 1980 (62,823) and 

2000 (117,644) (State of Hawai‘i, 2007). Toward the latter 

part of the 20th century, the general trend of land use on Maui 

shifted from large-scale plantation agriculture to other land 

uses. Although one large sugarcane plantation (Hawaiian 

Commercial and Sugar Company) continues to operate in 

central Maui, much of the land previously used for sugarcane 

cultivation in the Nā Wai ‘Ehā area has been developed for 

urban uses or is used for grazing and diversified agriculture. 

Climate

The climate on Maui is characterized by mild 

temperatures, cool and persistent trade winds, a rainy winter 

season from October through April, and a dry summer season 

from May through September (Blumenstock and Price, 1967; 

Sanderson, 1993). The climate is controlled primarily by 

topography and the position of the North Pacific anticyclone 

and other migratory weather systems relative to the island. 

During the dry season, the stability of the North Pacific 

anticyclone produces persistent northeasterly winds known 

locally as trade winds. Summer trade winds blow 80 to 95 

6 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
percent of the time. During the rainy season, frequent passage 

of migratory weather systems near the Hawaiian Islands 

results in less persistent trade winds. Winter trade winds blow 

50 to 80 percent of the time. Southerly winds associated with 

low-pressure systems can bring heavy rains to the island. 

Rainfall

The central interior part of West Maui Mountain 

receives the highest mean annual rainfall on the island, a 

pattern controlled by the orographic lifting of moisture-laden 

northeasterly trade winds along the windward slope of the 

mountain. The moisture-laden air mass cools as it rises up 

the slopes of the mountain, resulting in condensation, cloud 

formation, and high rainfall near the topographic peak of 

the mountain. Rainfall on West Maui is characterized by 

maxima at high altitudes and steep spatial gradients in the 

interior areas (fig. 1). Maximum mean annual rainfall is 

more than 350 in. near the summit of West Maui Mountain 

(Giambelluca and others, 1986). Mean annual rainfall over 

coastal areas of West Maui is much lower, ranging from 40 to 

60 in. over the northwestern part to less than 15 in. over the 

southern part. In comparison, mean annual rainfall over the 

open ocean is estimated at 22 to 28 in. (Dorman and Bourke, 

1979; Elliot and Reed, 1984). Mean annual rainfall over West 

Maui Mountain can vary by more than 200 in. over a mile 

of horizontal distance in the wetter interior areas. Over the 

drier central isthmus, the mean annual rainfall is much more 

uniform, varying by less than 5 in. over a mile of horizontal 

distance in places. 

Within the drainage basin of Waihe‘e River, mean annual 

rainfall ranges from less than 30 in. near the coast to more 

than 310 in. near the headwater area. Within the drainage basin 

of Waiehu Stream, mean annual rainfall ranges from less than 

30 in. near the coast to more than 160 in. near the headwater 

area. Within the drainage basin of ‘Īao Stream, mean annual 

rainfall ranges from less than 30 in. near the coast to more 

than 350 in. near the headwater area. Within the drainage basin 

of Waikapū Stream, mean annual rainfall ranges from less than 

15 in. near the coast to about 160 in. near the headwater area.

Within the study area, the seasonal pattern of rainfall is most 

pronounced in areas of low to moderate rainfall (fig. 4). In areas 

of low to moderate rainfall, the wettest months are from October 

through April and the driest months are from May through 

September. In wetter areas, variability in rainfall throughout 

the year is much less pronounced (fig. 4). The annual pattern of 

rainfall in wetter areas is characterized by three minima and three 

maxima (Giambelluca and others, 1986). 

Hydrogeologic Setting

The valleys of Waihe‘e River, Waiehu Stream, ‘Īao 

Stream, and Waikapū Stream have been deeply eroded, 

exposing volcanic dikes. The erosion likely was enhanced 

by high rainfall in the interior part of West Maui Mountain. 

Within the study area, the geologic setting consists of volcanic 

rocks overlain by sedimentary deposits at lower altitudes. 

Exposed volcanic rocks in the study area mainly are from the 

shield-building stage of the West Maui Volcano. A coastal 

plain formed by sedimentary deposits is about one-half mile 

wide near Waihe‘e Stream and about 2 miles wide near ‘Īao 

Stream. The sedimentary deposits are continuous to the south 

in the central isthmus and are truncated to the north by sea 

cliffs. The hydrogeologic setting controls the occurrence of 

and interaction between surface water and groundwater in the 

study area. In some places, the presence of low-permeability 

rocks that impede groundwater flow may create high 

groundwater levels and result in discharge of groundwater to 

streams and perennial streamflow.

Geology

The geologic setting of the Island of Maui has been 

described in detail by numerous investigators (for example, 

Stearns and Macdonald, 1942; Yamanaga and Huxel, 1970; 

Macdonald and others, 1983; Stearns, 1985). Langenheim 

and Clague (1987) described and renamed the stratigraphic 

framework of volcanic rocks on Maui. The exposed rocks of 

West Maui Volcano (fig. 5) are named the Wailuku Basalt, the 

Honolua Volcanics, and the Lahaina Volcanics, respectively 

representing the shield stage and postshield caldera-filling 

phase, the postshield stage, and the rejuvenated stage of 

volcanism. The Wailuku Basalt consists of shield-stage lava of 

tholeiitic basalt, olivine tholeiitic basalt, and picritic tholeiitic 

basalt and postshield-stage caldera-filling lava of alkalic 

basalt; the Honolua Volcanics consists of postshield-stage 

lava of mugearite, trachyte, and hawaiite; and the Lahaina 

Volcanics consists of rejuvenated-stage lava of basanite and 

pricritic basanite (Langenheim and Clague, 1987). No mapped 

Lahaina Volcanics exists in the study area. 

The shield stage represents the most voluminous phase 

of eruptive activity of the West Maui Volcano, during which 

more than 95 percent of the volcano was formed, mainly by 

thousands of relatively thin basalt lava flows. These flows 

emanated from a central caldera area near the heads of ‘Īao and 

Waikapū Stream Valleys and from fissures and vents radiating 

outward from the central caldera (Stearns and Macdonald, 

1942). Individual lava flows of the shield-stage Wailuku Basalt 

range in thickness from about 1 to 100 ft, averaging about 15 ft, 

and dip from 5 to 20 degrees away from their sources (Stearns 

and Macdonald, 1942). Shield-stage volcanism ended about 

1.35 million years ago and was followed by postshield-stage 

volcanism (Sherrod and others, 2006). The postshield stage is 

marked by a change in lava chemistry and character that led to 

the formation of massive lava flows. A thin red soil as much as 

5 ft thick may separate older shield-stage Wailuku Basalt from 

postshield-stage Honolua Volcanics in places. Individual lava 

Setting 7
flows of Honolua Volcanics generally are thicker than those 

of the Wailuku Basalt and form an incomplete veneer over 

Wailuku Basalt. Individual lava flows of Honolua Volcanics 

range in thickness from about 25 to 300 ft, averaging about 75 

ft, and dip from 3 to 20 degrees depending on the preexisting 

slopes over which they flowed (Stearns and Macdonald, 

1942). Within the study area, Honolua Volcanics is limited 

to small areas in the drainage basins of Waihe‘e River and 

Waikapū Stream. Postshield-stage volcanism ended about 1.2 

million years ago (Sherrod and others, 2006), and following 

the postshield stage, streams incised deep valleys (as much as 

2,000 to 4,000 ft deep in places) into the volcano (Stearns and 

Macdonald, 1942). 

The central part of the West Maui Volcano contains 

numerous intrusive volcanic dikes that generally trend radially 

outward from the central caldera area. Two main rift zones 

trending nearly north and south-southeastward from the central 

caldera are marked by numerous volcanic vents and dikes 

(Stearns and Macdonald, 1942; Sherrod and others, 2007), and 

the trends of these two rift zones are consistent with measured 

gravity anomalies (Kinoshita and Okamura, 1965). Macdonald 

and others (1983) indicated that the rift zones of West Maui 

are less well defined than those of most Hawaiian volcanoes, 

and that two additional rift zones (trending northeastward and 

southwestward) may exist. The boundary separating the dikeintruded and dike-free volcanic rocks is less than 1.5 mi inland 

from the coast near Waihe‘e River and is progressively farther 

inland to the south (Yamanaga and Huxel, 1970) (fig. 5). The 

dikes are visible in water-development tunnels or where they 

have been exposed by erosion in valleys. Dikes of the Wailuku 

Basalt generally are less than 10 ft wide and average about 1.5 

ft, whereas dikes of the Honolua Volcanics range from about 8 

to 25 ft wide (Stearns and Macdonald, 1942). 

Sedimentary deposits of consolidated older alluvium 

exist on the interfluves between Waihe‘e and Waikapū Streams 

at altitudes from about 100 to 1,000 ft. The older alluvium 

extends inland to altitudes greater than 2,000 ft in Waihe‘e and 

‘Īao Stream Valleys. Stearns and Macdonald (1942) indicate 

that these sedimentary deposits may have been emplaced 

during a period of submergence, when relative sea level stood 

MONTH

JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC

0.00

0.05

0.10

0.20

0.30

0.25

0.15

MEAN MONTHLY RAINFALL, IN PERCENTAGE OF MEAN ANNUAL RAINFALL

391

386

482

387.2

481.3

380

(23)

(28)

(45)

(74)

(247)

(393)

STATE KEY NUMBER (Value in parentheses 

 is mean annual rainfall, in inches)

low rainfall sites

high rainfall sites

intermediate rainfall sites

Figure 4. Mean monthly rainfall at selected rain-gaging stations, Maui, Hawaiÿi (data from Giambelluca and others, 1986).

8 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Figure 5. Generalized geology, central Maui, Hawaiÿi (modified from Stearns and Macdonald, 1942; Sherrod and 

others, 2007).

Waihe‘e River

Waiehu Str

North

Waiehu Stream

South Waiehu

Stream

ÿÏao

Stream

Waikapü

Stream

Huluhulupueo Str

Mananole Str

Waihe‘e

River

Ae Stream

Kinihäpa

Po

i Str

‘onähoahoa Str

Näkalaloa Str

Ukumehame Gulch

 

Olowalu

Stream

Pöhäkea

Gulch

Manawainui Gulch

Honoköh au

Stream

Mokulele Highway

Kahekili Highway

340

340

36

30

30

30

31

380

380

1

3

4

5

6

7 8 9

10

11

12

2

Puÿu Kukui

P A C I F I C

O C E A N

Kahului

Harbor

Keälia Pond

Waiheÿe Pt

Nehe Pt

McGregor Pt

Mäÿalaea

Papawai Pt

Waiheÿe

Waiehu

Kahului

Wailuku

Wailuku

Heights

Base modified from U.S. Geological Survey National 

Hydrography Dataset. Universal Transverse Mercator

projection, zone 4, NAD83 datum. 

0

0 1 2 3 KILOMETERS

0.5 1 2 MILES

156°35' 156°30'

20°50'

20°55'

PACIFIC OCEAN

Maui

Area

of map

EXPLANATION

SEDIMENTARY DEPOSITS

 Unconsolidated deposits, mainly younger alluvium

 Calcareous sand dunes

 Consolidated earthy deposits, chiefly older alluvium

VOLCANIC ROCKS

 Honolua Volcanics

 Kula Volcanics

 Wailuku Basalt

CONES, VENTS, DOMES, CRATERS, BOSSES

DIKES

CALDERA BOUNDARY

INFERRED BOUNDARY BETWEEN DIKE-

 IMPOUNDED AND FRESHWATER-LENS 

 SYSTEMS (Modified from Yamanaga and Huxel, 1970)

TUNNEL AND NUMBER

SPRING

1

Setting 9
A

B

C

Figure 6. Photographs of cobble beach near the mouths of selected 

streams, Maui, Hawaiÿi. A, Waiheÿe River (February 5, 2007). B, 

Waiehu Stream (June 30, 2006). C, ÿÏao Stream (March 17, 2005).

Figure 6. Photographs of cobble beach near the mouths of 

selected streams, Maui, Hawaiÿi. A, Waiheÿe River (February 

5, 2007). B, Waiehu Stream (June 30, 2006). C, ÿĪao Stream 

(March 17, 2005).

higher than it does today. The older alluvium is a poorly 

sorted, consolidated conglomerate, consisting of particles 

ranging from fine-grained particles to boulders (Yamanaga 

and Huxel, 1970). These deposits are thickest near the axes 

of large stream valleys. Information from a test hole near the 

lower reaches of ‘Īao Stream indicates that older alluvium 

extends to an altitude of at least 524 ft below sea level 

(Yamanaga and Huxel, 1970). 

Older dune deposits and unconsolidated younger 

alluvium generally are at altitudes below about 300 ft, except 

in stream valleys where younger alluvium may extend to 

higher altitudes. The older dune deposits veneer the older 

alluvium between Waihe‘e River and ‘Īao Stream and in the 

western part of the isthmus east and south of ‘Īao Stream. The 

dune deposits are visible in the lower reaches of Waiehu, ‘Īao, 

and Waikapū Streams. Stearns and Macdonald (1942, p. 151) 

indicated that migrating dunes may have blocked the original 

northern course of Waikapū Stream, which is marked by an 

abandoned channel entering Kahului Bay, diverting it to the 

south, where it currently discharges near Keālia Pond. The 

younger alluvium consists of deposits in stream channels and 

at the seaward extent of the older alluvium. Unconsolidated 

sedimentary deposits in stream channels range from finegrained particles to large boulders. A cobble beach (fig. 6) that 

is more than a mile long extends south from Waihe‘e Point 

(Stearns and Macdonald, 1942). Near the shore, terrestrial 

sedimentary deposits may be interbedded with marine deposits 

(Yamanaga and Huxel, 1970). 

Permeability describes the ease with which fluid can 

move through rock. The permeability of volcanic rocks is 

variable and depends on many factors, including the mode 

of emplacement and amount of weathering. Weathered 

volcanic rocks generally have a much lower permeability 

than unweathered volcanic rocks. Lava chemistry and 

topography also can affect permeability. In the study area, 

dike-free volcanic rocks are much more permeable than 

intrusive dikes and older sedimentary deposits and are limited 

to areas seaward of the dike-intruded area (fig. 5). Hydraulic 

conductivity is a quantitative measure of permeability. Rotzoll 

and others (2007) estimated the hydraulic conductivity of 

Wailuku Basalt to be comparable to other permeable dike-free 

volcanic rocks in Hawai‘i. 

Within the dike-intruded area, dikes reduce overall 

permeability of the volcanic rocks and impede flow of 

groundwater. In general, the overall permeability of a dikeintruded area decreases as the number of dike intrusions 

within the area increases. Although the thickness of individual 

dikes generally is less than 10 ft, dikes are hydrologically 

significant because they tend to impede the movement of 

groundwater, resulting in groundwater levels that are hundreds 

of feet above sea level within dike compartments. 

Older alluvium generally is poorly permeable and, in 

the study area, acts as a confining unit over the volcanicrock aquifer that retards the discharge of groundwater to the 

ocean. The dune deposits are more permeable than the older 

alluvium. Dune deposits may be hydrologically significant 

10 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
because water in streams may infiltrate into them and recharge 

underlying groundwater bodies. Younger alluvium commonly 

occurs in or near stream valleys. 

Surface-Water Resources

Upstream of existing diversions, Waihe‘e River and 

Waiehu, ‘Īao, and Waikapū Streams flow perennially because 

of sustained groundwater discharge and persistent rainfall. 

The natural median streamflows in Waihe‘e River and ‘Īao 

Stream may exceed 20 Mgal/d in places and are considerably 

greater than in Waiehu and Waikapū Streams, where natural 

median streamflows are less than 10 Mgal/d. All four streams 

are characterized by steep gradients in the mountainous 

headwater areas and flatter gradients near the coast. 

These streams are flashy because rainfall is intense, 

drainage basins are small, basins and streams are steep, and 

channel storage is limited. Stream stage, or water level, can 

rise several feet in less than an hour during periods of intense 

rainfall. Streamflow generated during periods of heavy rainfall 

has led to loss of human lives and property in the Nā Wai ‘Ehā 

area. In January 2002, three people lost their lives attempting to 

drive across a flooded stream crossing in the Waiehu area. 

Perennial flows in the upper reaches of the streams 

represent a reliable source of water for agricultural and 

other purposes. Native Hawaiians used surface water in the 

Nā Wai ‘Ehā area to cultivate large areas of taro, although 

the locations of many ancient ‘auwai (ditches) are largely 

unknown. For more than a century, ditch systems (figs. 7, A1) 

have diverted water by gravity from streams in the Nā Wai 

‘Ehā area for large-scale sugarcane cultivation. An average 

of about 67 Mgal/d of water was diverted from Waihe‘e 

River and Waiehu, ‘Īao, and Waikapū Streams for sugarcane 

irrigation (Yamanaga and Huxel, 1970). About 40 Mgal/d 

was diverted from Waihe‘e River; 3 Mgal/d from North 

Waiehu Stream; 3 Mgal/d from South Waiehu Stream; 18 

Mgal/d from ‘Īao Stream; and 3 Mgal/d from Waikapū Stream 

(Yamanaga and Huxel, 1970).

As of 2009, water continues to be diverted from each of 

the streams in the Nā Wai ‘Ehā area. Currently, three known 

diversions exist on Waihe‘e River, one on North Waiehu 

Stream, three on South Waiehu Stream, three on ‘Īao Stream, 

and five on Waikapū Stream (table 1). A brief description of 

these diversions is provided in this section. Additional details 

and photographs of the diversions are available in appendix A. 

Three known diversions currently exist on Waihe‘e 

River: Waihe‘e Ditch, with an intake near an altitude of 600 

ft; Spreckels Ditch, with an intake near an altitude of 400 ft; 

and the Field 1 diversion, with an intake near an altitude of 

260 ft (fig. 7). The main diversions from Waihe‘e River are the 

Waihe‘e and Spreckels Ditches. The Waihe‘e Ditch has two 

intake grates in Waihe‘e River in a reach that is bifurcated by 

an island. The Waihe‘e Ditch intakes have a combined design 

capacity of 60 Mgal/d, although a downstream control gate 

limits flow in the ditch to about 40 Mgal/d (Suzuki, 2007). The 

Spreckels Ditch intake in Waihe‘e River has a design capacity 

of 30 Mgal/d, although a control gate limits flow in the ditch to 

about 12 Mgal/d (Suzuki, 2007). About 6 Mgal/d of the water 

diverted by the Waihe‘e Ditch commonly discharges into the 

Spreckels Ditch (Suzuki, 2007), about 2,000 ft downstream of 

the Spreckels Ditch intake. The capacity and frequency of use 

of the Field 1 intake are unknown.

The only known existing diversion on North Waiehu 

Stream is the North Waiehu Ditch (fig. 7), which has an intake 

near an altitude of 880 ft. A downstream control gate is set 

to limit flow in the North Waiehu Ditch to about 1.5 Mgal/d 

(Suzuki, 2007). Three known diversions currently exist on 

South Waiehu Stream: two ‘auwai for private use, with intakes 

near altitudes of 620 ft (north side of stream) and 570 ft (south 

side of stream), and the Spreckels Ditch, with an intake near 

an altitude of 270 ft. The capacities of the diversions on South 

Waiehu Stream are not known. Limited measurements indicate 

(1) less than 0.5 Mgal/d flow in each of the two ‘auwai and (2) 

the Spreckels Ditch intake is capable of diverting all of the low 

flow of South Waiehu Stream up to at least 1 Mgal/d. 

Three known diversion intakes currently exist on ‘Īao 

Stream: the ‘Īao-Waikapū and ‘Īao-Māniania Ditches, which 

share a common intake near an altitude of 780 ft; Spreckels 

Ditch, with an intake near an altitude of 250 ft; and a small 

private intake near an altitude of 650 ft. The intake for the 

‘Īao-Waikapū and ‘Īao-Māniania Ditches has a design capacity 

of 60 Mgal/d, although a downstream control gate limits 

combined flow in the ‘Īao-Waikapū and ‘Īao-Māniania Ditches 

to about 20 Mgal/d (18 Mgal/d to the ‘Īao-Waikapū Ditch and 

2 Mgal/d to the ‘Īao-Māniania Ditch) (Suzuki, 2007). The 

capacity of the intake for Spreckels Ditch is unknown, although 

it likely exceeds 10 Mgal/d on the basis of available discharge 

measurements and observations. The capacity of the intake for 

the small private ‘auwai with intake near an altitude of 650 ft 

is unknown, although two measurements (September 21, 2004, 

and July 24, 2006) indicated flows ranging from 0.054 to 0.090 

Mgal/d (0.083 to 0.14 ft3

/s) in the system. 

Five known diversion intakes currently exist on Waikapū 

Stream: (1) the South Side Ditch (also referred to as South 

Waikapū Ditch) is the most upstream diversion, with an intake 

near an altitude of 1,120 ft; (2) the Everett Ditch (also referred 

to as Palolo Ditch) intake is near an altitude of 900 ft; (3) a 

private, community ‘auwai diverts water near an altitude of 560 

ft; (4) the Waihe‘e Ditch intake is near an altitude of 440 ft; 

and (5) the Reservoir 6 intake is near an altitude of 410 ft. The 

intake for the South Side Ditch has a design capacity of about 

5 Mgal/d (Suzuki, 2007), although a control gate is set to limit 

flow in the South Side Ditch to about 3 Mgal/d (Suzuki, 2007). 

The capacity of the Everett Ditch intake is unknown but is less 

than the typical low flow of Waikapū Stream. During April 

29 and 30, 2008, discharges in the Everett Ditch near gaging 

station 16649000 (fig. 7) were 0.36 and 0.14 Mgal/d (0.56 

and 0.21 ft3

/s), respectively. Measured discharges in Waikapū 

Stream, about 600 ft upstream of the Everett Ditch intake, 

Setting 11
Waihe‘e River

Waiehu Str

North

Waiehu

Stream

South Waiehu

Stream

‘Ïao

Stream

Waikapü

Stream

Huluhulupueo Str

Mananole Str

Waihe‘e

River

Ae Stream

Kinihäpai

Po

Str

‘onähoahoa Str

Näkalaloa Str

Ukumehame Gulch

 

Olowalu

Stream

Pöhäkea

Gulch

Manawainui Gulch

Honoköhau Stream

16612000

16610000

16611000

16605000

16649000

16650000

16609000

16608000

16609500

16604500

16604000

16607000

16613500

16616000

16650200

16648000

16615000 

16613000

16614000

16650500

Mokulele Highway

Kahekili Highway

340

340

36

30

30

30

31

380

380

Waiheÿe Ditch

Waiheÿe

Ditch

Kama Ditch

N. Waiehu Dt

South Waikapü Dt

Spreckels Ditch

‘Ïao–Mäniania

Ditch Everett

Dt

Kama Dt

Spreckels Ditch

Ïao–Waikapü Ditch

Waiheÿe Ditch

Puÿu Kukui

P A C I F I C

O C E A N

482

391

386

380

481.3

387.2

Kahului

Harbor

Keälia Pond

Waiheÿe Pt

Nehe Pt

McGregor Pt

Mäÿalaea

Papawai Pt

Waiheÿe

Waiehu

Kahului

Wailuku

Wailuku

Heights

Base modified from U.S. Geological Survey National 

Hydrography Dataset. Universal Transverse Mercator

projection, zone 4, NAD83 datum. Relief from U.S. 

Geological Survey digital elevation models, 1:24,000. 

EXPLANATION

16604500

DITCH SYSTEM

INFERRED BOUNDARY BETWEEN DIKE-IMPOUNDED

 AND FRESHWATER-LENS SYSTEMS (Modified 

 from Yamanaga and Huxel, 1970)

STREAM- OR DITCH-GAGING STATION AND NUMBER

380 RAIN-GAGING STATION AND STATE KEY NUMBER

0

0 1 2 3 KILOMETERS

0.5 1 2 MILES

156°35' 156°30'

20°50'

20°55'

PACIFIC OCEAN

Maui

Area

of map

Figure 7. Ditch systems, stream-gaging stations, and selected rain-gaging stations, Na ̄ Wai ÿEha ̄ area, Maui, Hawaiÿi.

12 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
were 3.19 and 1.29 Mgal/d (4.93 and 1.99 ft3

/s), respectively, 

on April 29 and 30, 2008. The capacity of the private ‘auwai 

with an intake near an altitude of 560 ft is unknown, although 

measurements from October 28, 2004, indicate that 0.66 

Mgal/d (1.02 ft3

/s) was diverted and about 0.42 Mgal/d (0.65 

ft3

/s) of this leaked or was returned back to the stream. The 

capacities of the Waihe‘e Ditch and Reservoir 6 intakes each 

exceed 1 Mgal/d but are otherwise unknown. 

Groundwater Resources

The Nā Wai ‘Ehā area contains three types of fresh 

groundwater systems: (1) dike-impounded groundwater; (2) 

a freshwater lens floating on saltwater; and (3) perched water 

(Gingerich and Oki, 2000). Dike-impounded groundwater 

occurs inland at relatively high altitudes and consists of 

freshwater contained in dike compartments. Closer to the coast, 

a freshwater-lens system is contained in dike-free volcanic 

rocks and sedimentary deposits. Perched water also can occur in 

the sedimentary deposits where low-permeability rocks impede 

the downward movement of groundwater sufficiently to allow a 

saturated water body to develop in otherwise unsaturated rocks.

In the Nā Wai ‘Ehā area, water enters and recharges the 

freshwater-lens system by direct infiltration of precipitation 

and irrigation water, seepage from flowing streams where the 

water table is below the streambed, and inflow from upgradient 

groundwater bodies (for example, dike-impounded and perched 

water bodies). The low-permeability coastal sedimentary 

deposits impede the discharge of freshwater from, and the 

inflow of saltwater to, the freshwater-lens system.

Significant development of groundwater from the Nā Wai 

‘Ehā area began with the construction of tunnels to divert dikeimpounded groundwater (Meyer and Presley, 2001). Twelve 

tunnels are known to have been excavated in the Nā Wai ‘Ehā 

area between 1900 and 1926 (fig. 5) (Stearns and Macdonald, 

1942). Eight of the tunnels were excavated in the dike complex 

and tap dike-impounded groundwater. The other four tunnels 

were excavated mainly in alluvium. About 9 Mgal/d of dikeimpounded groundwater was developed by tunnels (table 2), 

although most of the water (7.5 Mgal/d) might have discharged 

naturally to streams below the level of the tunnels had the water 

not been intercepted by the tunnels (Stearns and Macdonald, 

1942; Yamanaga and Huxel, 1970). Most of the dike-impounded 

groundwater developed (intercepted) by tunnels likely 

discharges back into the streams. 

The large-scale withdrawal of groundwater from the 

freshwater lens in the Nā Wai ‘Ehā area began in 1948 in the 

‘Īao area (Meyer and Presley, 2001). The freshwater lens in the 

Waihe‘e area, which is adjacent to the ‘Īao area, was developed 

beginning in 1997. Currently (2009), groundwater is pumped 

by five major wells or well fields in the ‘Īao area and two well 

fields in the Waihe‘e area. In general, groundwater levels in the 

‘Īao and Waihe‘e areas have declined, the chloride concentration 

of water pumped by some wells has increased, and, as indicated 

by salinity profiles from an existing deep monitor well in 

the ‘Īao area, the brackish-water transition zone between the 

freshwater and the underlying saltwater has risen (Meyer and 

Presley, 2001; Gingerich, 2008).

Interaction Between Groundwater and 

Surface Water

Groundwater and surface water interact in different 

ways, depending on the geology and hydrology of an 

area. In the dike-impounded groundwater system, the low 

permeability of the dikes causes groundwater levels to 

build up behind them, typically on the order of hundreds or 

thousands of feet above sea level. In the Nā Wai ‘Ehā area, 

stream erosion has carved deeply incised valleys in which 

the stream channels have been lowered below the level of 

the water table of the dike-impounded groundwater body, 

creating the opportunity for streams to drain dike-impounded 

groundwater (fig. 8). In reaches where the groundwater table 

is higher than the adjacent stream channel, the streams are 

Table 1. Surface-water diversion intakes, Na− Wai ÿEha−, Maui, 

Hawaiÿi.

[—, data not available; Mgal/d, million gallons per day]

Intake of ditch system 

or small private ÿauwai 

(ditch)

Altitude,

in feeta

Design 

capacity,

in Mgal/d

Intake capacity 

setting,

in Mgal/d

Waiheÿe River

Waiheÿe Ditch 600 b

60 c40

Spreckels Ditch 400 b

30 c12

Field 1 260 — —

North Waiehu Stream

North Waiehu Ditch 880 — c

1.5

South Waiehu Stream

Left (north) ÿauwai 620 — —

Right (south) ÿauwai 570 — —

Spreckels Ditch 270 —d —d

ÿÏao Stream

ÿÏao-Waikapü and 

ÿÏao-Mäniania 

Ditches

780 b

60 c20

Right (south) ÿauwai 650 — —

Spreckels Ditch 250 —e —e

Waikapü Stream

South Side Ditch 1,120 b

5 c3

Everett (Palolo) Ditch 900 — —

Left (north) ÿauwai 560 — —

Waiheÿe Ditch 440 —d —d

Reservoir 6 410 —d —d

a

Altitude determined from topographic map.

b

Suzuki (2007). 

c

Gate setting (Suzuki, 2007). 

d

Capacity unknown but greater than 1 Mgal/d.

e

Capacity unknown but likely greater than 10 Mgal/d.

Setting 13
said to be “gaining” because groundwater contributes to 

streamflow. 

In general, Waihe‘e River and Waiehu, ‘Īao, and Waikapū 

Streams are gaining in reaches where they intersect the dikeimpounded water body (fig. 5). Discharge from the dikeimpounded water body maintains perennial flow in these 

streams. Streamflow may vary in response to rainfall, but flow 

continues even during extended dry-weather periods because 

of sustained groundwater discharge to the stream. 

In lower altitude areas lying above the freshwater lens, the 

stream channels generally are above the groundwater table. At 

these lower altitudes, the water table is only a few feet or tens of 

feet above sea level, as opposed to hundreds or thousands of feet 

in the dike-impounded system. Where an unsaturated zone exists 

between the stream and water table, a stream may lose water and 

act as a source of groundwater recharge for the freshwater-lens 

system. Waihe‘e River and ‘Īao, Waiehu, and Waikapū Streams 

may lose water in reaches overlying the freshwater-lens system 

where the channel bottoms are above the water table. 

In places, shallow groundwater in the alluvium 

within stream channels also may discharge to the stream. 

Groundwater within the alluvium may be hydraulically 

connected to and part of a dike-impounded groundwater 

body or freshwater-lens system. Groundwater within 

the alluvium also may be perched on low-permeability 

material and separated from an underlying dike-impounded 

groundwater body or freshwater-lens system by a zone of 

unsaturated rock. At low altitudes close to the coast in the 

Nā Wai ‘Ehā area, stream channels may intersect the water 

table in sedimentary deposits, causing some streams to gain 

near their mouths. Where the pressure in the groundwater 

system is high enough to raise the water to the land surface, 

groundwater also can discharge in the form of coastal springs 

or seeps that are not within defined stream channels. 

Potential Effects of Groundwater Withdrawals on 

Streamflow

Groundwater withdrawals can affect streamflow 

in reaches where the groundwater body is hydraulically 

connected to the stream, and this also may cause streamflow 

to be affected in downstream reaches. When withdrawal 

14 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄

Table 2. Water-development tunnels, Na− Wai ÿEha−, Maui, Hawaiÿi. 

[Refer to fig. 5 for locations; —, not applicable or data not available; Mgal/d, million gallons per day]

Tunnel no. Year

constructed

Altitude,

in feeta

Length,

in feetb

Tunnel discharge, in Mgal/d

Geologic description August 1911

(Martin and 

Pierce, 1913)

Stearns and

 Macdonald, 1942c

Waiheÿe

1 1909 1,625 2,200 5.2 4.6 Older alluvium and dike-intruded Wailuku Basalt 

2 1909 1,650 2,500 0.38 1.0 Older alluvium, dike-intruded Wailuku Basalt, breccia

Waiehu 

3 1902 300 500 — 0.25 Alluvium

ÿÏao 

4 1906 1,425 d

2,500 0.40 0.075 Dike-intruded caldera complex

5 1906 1,475 caved 0.62 caved Dike-intruded caldera complex

6 1926 1,305 1,413 — e

0 Dike-intruded Wailuku Basalt

7 1938, 1945 787 2,630 — f

2.3 Dike-intruded Wailuku Basalt

8 1900 700 caved — caved Alluvium and Wailuku Basalt

9 1900 444 1,000 — 0.15 Alluvium

10 1900 240 2,000 — 0.25 Alluvium

Waikapü 

11 1900, 1906 1,800 2,943 1.7 1.0 Dike-intruded Wailuku Basalt

12 1905 1,770 g

1,650 — 0.007 Dike-intruded vent breccia of caldera

Total — — — — 9.6 —

a

Altitude determined by barometer, except for tunnel 6, for which altitude was determined by level line (Stearns and Macdonald, 1942)

b

Includes laterals, if any. 

c

Mostly estimated.

d

Tunnel is caved in at 650 feet from portal; cuts 21 dikes in first 650 feet. 

e

Reported discharge was 0.60 Mgal/d before construction of tunnel 7 (Stearns and Macdonald, 1942). Tunnel 6 was dry after construction of tunnel 7 (Yamanaga and Huxel, 1970).

f

Reported discharge from 1951 was 2.3 Mgal/d (Yamanaga and Huxel, 1970). Measured discharge was 2.0 Mgal/d on December 27, 1940, before tunneling by Wailuku Sugar Company. 

Records of discharge kept during excavation indicate a maximum flow of 4 Mgal/d (Stearns and Macdonald, 1942) g

Tunnel is caved in at 1,500 feet from portal; water slightly thermal and gas present. Another tunnel reported to be in this area was not found. 
Water table

Freshwater

Saltwater

Dike

Dike

Stream

Dikes and ground surface 

are transparent, revealing 

differences in water levels 

in the freshwater-lens 

and dike-impounded 

groundwater systems.

Dike-impounded groundwater 

systems in Hawaiÿi generally 

contain numerous dikes that 

commonly intersect each other, 

although only two are shown in 

this conceptual diagram.

Freshwater‐lens system

Stream is above the water table, 

creating a losing stream reach. 

Arrows below stream indicate 

groundwater recharge.

 Exposed dike at surface

Stream intersects the water

table, creating a gaining stream

reach. Arrows below stream

indicate groundwater discharge.

Figure 8. Conceptual diagram showing relation between surface water and groundwater within the drainage basin of a stream. The cutaway views at the top are split along the main stream.

Setting 15
from a well begins, water is initially removed from aquifer 

storage, and groundwater levels in the vicinity of the well begin 

to decline. If withdrawal is stopped and groundwater recharge 

remains steady, water lost from storage eventually will be 

regained and groundwater levels will recover as the system 

returns to prewithdrawal conditions. If withdrawal from the well 

continues at a steady rate, the zone over which groundwater 

levels decline expands outward from the well as additional water 

is removed from storage. Water-level decline is greatest at the 

withdrawal site and decreases outward from the well, forming 

what is known as a cone of depression. The cone of depression 

eventually reaches areas where water is discharging to the 

ocean or streams, or where recharge to the groundwater body 

can occur. The shape of the cone of depression surrounding the 

withdrawal site generally is not symmetrical, because of the 

presence of inhomogeneities (for example, low-permeability 

geologic features), anisotropy, or recharge and discharge 

boundaries. As groundwater levels decline near a discharge 

area, the rate of discharge in that area decreases. As water levels 

decline near a potential recharge area, the rate of recharge in that 

area may increase.

Long-term steady withdrawal of groundwater by a well 

is eventually balanced by enhanced recharge or loss of natural 

discharge (provided the rate of withdrawal is not greater than 

the possible balancing sources of water), and water levels cease 

to decline further. Long-term withdrawal may enhance recharge 

in areas where water may otherwise have been (1) lost to 

evapotranspiration where plants extract groundwater from below 

the water table, or (2) discharged to springs or streams (see, for 

example, Lohman, 1979). Long-term withdrawal may lower the 

water table below the roots of plants or below the level of springdischarge sites, creating a condition that could lead to enhanced 

recharge. Where long-term steady withdrawal by a well does 

not result in enhanced recharge, natural discharge is reduced by 

an amount equal to the withdrawal (provided none of the water 

that is withdrawn contributes to recharge). In Hawai‘i, long-term 

withdrawal of groundwater generally results in a reduction of 

groundwater discharge to the ocean or streams. 

If the zone of groundwater-level declines caused by 

withdrawal extends to a stream that is hydraulically connected 

to the groundwater body, streamflow may be reduced by (1) 

a reduction of groundwater discharge to the stream where the 

water level in the adjacent aquifer is higher than the stream or 

(2) enhanced opportunity for surface-water losses through the 

streambed where the water level in the adjacent aquifer is lower 

than the stream. Development tunnels, wells, and shafts that 

withdraw groundwater from the dike-impounded groundwater 

body or freshwater-lens system all can cause such reductions in 

streamflow. 

Stream Fauna

Both native and non-native aquatic species can be 

found in Nā Wai ‘Ehā streams. The isolation of the Hawaiian 

Islands has resulted in the evolution of a unique native stream 

community. Recent human activities have resulted in the 

introduction of a number of non-native species into the Nā 

Wai ‘Ehā area, and these non-native species may compete with 

native species for available resources or may prey on the native 

species directly. Native stream fauna utilize a variety of macroand microhabitats within stream ecosystems. The availability 

of suitable habitat for native fish, snails, and shrimp species 

found in the Nā Wai ‘Ehā area is examined in a later section 

(“Effects of Surface-Water Diversions on Physical Habitat”) of 

this report.

Native Species

In Hawai‘i, native invertebrate (mollusks and 

crustaceans) species include the endemic (found only in 

Hawai‘i) freshwater snail, Neritina granosa Sowerby, 

1825, commonly referred to by the Hawaiian name hïhïwai; 

the endemic brackish-water snail, Neritina vespertinus

(Sowerby, 1849), referred to as hapawai; the endemic 

prawn, Macrobrachium grandimanus (Randall, 1840), 

referred to as ‘ōpae ‘oeha‘a; and the endemic mountain 

shrimp, Atyoida bisulcata (Randall, 1840), referred to as 

‘ōpaekala‘ole or mountain ‘ōpae. Native vertebrate species 

include fish, collectively referred to as ‘o‘opu wai. The five 

‘o‘opu include an endemic eleotrid (family: Eleotridae), 

Eleotris sandwicensis (Vaillant and Sauvage, 1875), referred 

to as ‘o‘opu ‘akupa (or ‘ōkuhe), and fishes in the family 

Gobiidae, collectively referred to as gobies, including the 

endemic gobies Lentipes concolor (Gill, 1860), known as 

‘o‘opu ‘alamo‘o (or hi‘ukole); Sicyopterus stimpsoni (Gill, 

1860), known as ‘o‘opu nōpili; Stenogobius hawaiiensis, the 

teardrop goby also known as ‘o‘opu naniha (Watson, 1991); 

and the indigenous (native to Hawai‘i and elsewhere) goby 

Awaous guamensis (Valenciennes, 1837), also known as 

‘o‘opu nākea. The juveniles of an endemic nearshore marine 

fish species, Kuhlia xenura (Jordan and Gilbert, 1882), also 

known as the Hawaiian flagtail or āholehole, are commonly 

found in lower stream reaches and estuaries. Each of the 

native species listed above has been observed in at least one 

stream in the Nā Wai ‘Ehā area in the past (tables 3–6).

The Nā Wai ‘Ehā watersheds also are inhabited by native 

Hawaiian damselflies of the endemic genus Megalagrion referred 

to as pinao ‘ula. The larvae of most of the 23 described species 

are aquatic, and many adults are observed on plants and rocks 

in and around streams (Polhemus and Asquith, 1996). Because 

of habitat loss and degradation and predation by alien species, 

Megalagrion damselfly populations have been in decline and 

some species have been extirpated from entire islands (Polhemus, 

1993). Because of their sensitivity to environmental disturbance, 

the Megalagrion damselflies are considered indicators of 

ecosystem health (DiSalvo and others, 2003). The damselflies that 

were observed during this study in the Nā Wai ‘Ehā watersheds 

include M. blackburni McLachlan, 1883 (Blackburn’s Hawaiian 

Damselfly), M. hawaiiense (McLachlan, 1883) (Hawaiian Upland 

16 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Stream Fauna 17

Table 3. Native aquatic species observed in Waiheÿe River from surveys during 1978–2008, Maui, Hawaiÿi.

[HSA, Hawaiÿi Stream Assessment (Hawaiÿi Cooperative Park Service Unit, 1990); DAR, Hawaiÿi Department of Land and Natural Resources, Division of 

Aquatic Resources; spp., more than one species; NG1, native species group 1; NG2, native species group 2; End, endemic; Ind, indigenous; p, present; a, abundant; va, very abundant; —, no data]

Class Family Genus/Species Hawaiian name HSA

classification Status Observations

HSA DAR Ford1 This study

Gastropoda Neritidae Neritina vespertinus hapawai NG2 End — — — —

Gastropoda Neritidae Neritina granosa hïhïwai NG1 End — 1995(p)2 — —

Crustacea Atyidae Atyoida bisulcata ‘öpaekala‘ole NG2 End 1978(a) 2008(a)3 2007(a) 2008(a)

Crustacea Palaemonidae Macrobrachium grandimanus ‘öpae ‘oeha‘a NG2 Ind — — — —

Insecta Coenagrionidae Megalagrion spp. pinao ‘ula — End — (p)4 2007(p) 2008(a)

Osteichthyes Eleotridae Eleotris sandwicensis ‘o‘opu ‘akupa NG2 End — — — 2008(p)

Osteichthyes Gobiidae Stenogobius hawaiiensis ‘o‘opu naniha NG2 End — — — —

Osteichthyes Gobiidae Awaous guamensis ‘o‘opu näkea NG1 Ind 1989(p) 2008(a)3 2007(a) 2008(va)

Osteichthyes Gobiidae Sicyopterus stimpsoni ‘o‘opu nöpili NG1 End 1978(a) 2008(a)3 2007(a) 2008(va)

Osteichthyes Gobiidae Lentipes concolor ‘o‘opu ‘alamo‘o NG1 End 1978(a) 2008(a)3 2007(va) 2008(va)

Osteichthyes Kuhliidae Kuhlia xenura5 äholehole NG2 End — — — 2008(a) 

1

Ford and others (2008).

2

DAR observation (State of Hawaiÿi, 2004).

3

DAR observation (D. Polhemus, written commun., 2009).

4

Undated DAR observation from the Atlas of Hawaiian Watersheds and Their Aquatic Resources (Parham and others, 2008).

5

Revised name for species previously identified as K. sandvicensis.

Table 4. Native aquatic species observed in Waiehu Stream from surveys during 1961–2008, Maui, Hawaiÿi.

[HSA, Hawaiÿi Stream Assessment (Hawaiÿi Cooperative Park Service Unit, 1990); DAR, Hawaiÿi Department of Land and Natural Resources, Division of 

Aquatic Resources; spp., more than one species; NG1, native species group 1; NG2, native species group 2; End, endemic; Ind, indigenous; p, present; a, abundant; —, no data]

Class Family Genus/Species Hawaiian name HSA

classification Status Observations

HSA DAR Ford1 This Study

Gastropoda Neritidae Neritina vespertinus hapawai NG2 End — (p)2 — —

Gastropoda Neritidae Neritina granosa hïhïwai NG1 End — (p)2 — —

Crustacea Atyidae Atyoida bisulcata ‘öpaekala‘ole NG2 End 1961(a) 2008(p)3 2007(a) 2008(p)

Crustacea Palaemonidae Macrobrachium grandimanus ‘öpae ‘oeha‘a NG2 Ind — — — —

Insecta Coenagrionidae Megalagrion spp. pinao ‘ula — End — (p)2 2007(a) 2008(a)

Osteichthyes Eleotridae Eleotris sandwicensis ‘o‘opu ‘akupa NG2 End — (p)2 — —

Osteichthyes Gobiidae Stenogobius hawaiiensis ‘o‘opu naniha NG2 End — — — —

Osteichthyes Gobiidae Awaous guamensis ‘o‘opu näkea NG1 Ind 1961(p) 2008(p)3 2007(p) 2008(a)

Osteichthyes Gobiidae Sicyopterus stimpsoni ‘o‘opu nöpili NG1 End 1961(a) 2008(p)3 2007(p) 2008(a)

Osteichthyes Gobiidae Lentipes concolor ‘o‘opu ‘alamo‘o NG1 End — 2008(p)3 2007(a) 2008(a)

Osteichthyes Kuhliidae Kuhlia xenura4 äholehole NG2 End — (p)2 — —

1

Ford and others (2008).

2

Undated DAR observation from the Atlas of Hawaiian Watersheds and Their Aquatic Resources (Parham and others, 2008).

3

DAR observation (D. Polhemus, written commun., 2009).

4

Revised name for species previously identified as K. sandvicensis.
18 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄

Table 5. Native aquatic species observed in ÿI

−

ao Stream from surveys during 1970–2008, Maui, Hawaiÿi.

[HSA, Hawaiÿi Stream Assessment (Hawaiÿi Cooperative Park Service Unit, 1990); DAR, Hawaiÿi Department of Land and Natural Resources, Division of 

Aquatic Resources; spp., more than one species; NG1, native species group 1; NG2, native species group 2; End, endemic; Ind, indigenous; p, present; a, abundant; va, very abundant; —, no data]

Class Family Genus/Species Hawaiian name HSA

classification Status Observations

HSA DAR Ford1 This study

Gastropoda Neritidae Neritina vespertinus hapawai NG2 End — — — —

Gastropoda Neritidae Neritina granosa hïhïwai NG1 End — (p)2 — 2006(p)

Crustacea Atyidae Atyoida bisulcata ‘öpaekala‘ole NG2 End 1989(va) 1994(p)3 2007(va) 2008(p)

Crustacea Palaemonidae Macrobrachium grandimanus ‘öpae ‘oeha‘a NG2 Ind — — — —

Insecta Coenagrionidae Megalagrion spp. pinao ‘ula — End — (p)2 2007(p) 2008(p)

Osteichthyes Eleotridae Eleotris sandwicensis ‘o‘opu ‘akupa NG2 End — (p)2 — —

Osteichthyes Gobiidae Stenogobius hawaiiensis ‘o‘opu naniha NG2 End — (p)2 — —

Osteichthyes Gobiidae Awaous guamensis ‘o‘opu näkea NG1 Ind 1989(p) 1994(p)3 2007(p) 2008(a)

Osteichthyes Gobiidae Sicyopterus stimpsoni ‘o‘opu nöpili NG1 End 1970(p) (p)2 2007(p) 2008(a)

Osteichthyes Gobiidae Lentipes concolor ‘o‘opu ‘alamo‘o NG1 End — 1994(p)3 2007(p) 2008(a)

Osteichthyes Kuhliidae Kuhlia xenura4 äholehole NG2 End 1989(p) (p)2 — —

1

Ford and others (2008).

2

Undated DAR observation from the Atlas of Hawaiian Watersheds and Their Aquatic Resources (Parham and others, 2008).

3

DAR observation from tributary of ÿÏao Stream (State of Hawaiÿi, 2004).

4

Revised name for species previously identified as K. sandvicensis.

Table 6. Native aquatic species observed in Waikapu− Stream from surveys during 1961–2008, Maui, Hawaiÿi.

[HSA, Hawaiÿi Stream Assessment (Hawaiÿi Cooperative Park Service Unit, 1990); DAR, Hawaiÿi Department of Land and Natural Resources, Division of 

Aquatic Resources; spp., more than one species; NG1, native species group 1; NG2, native species group 2; End, endemic; Ind, indigenous; p, present; a, abundant; ?, uncertain identification; —, no data]

Class Family Genus/Species Hawaiian name HSA

classification Status Observations

HSA DAR Ford1 This study

Gastropoda Neritidae Neritina vespertinus hapawai NG2 End — (p)2 — —

Gastropoda Neritidae Neritina granosa hïhïwai NG1 End — — — —

Crustacea Atyidae Atyoida bisulcata ‘öpaekala‘ole NG2 End 1961(a) (p)2 2007(a) 2008(a)

Crustacea Palaemonidae Macrobrachium grandimanus ‘öpae ‘oeha‘a NG2 Ind — (p)2 — —

Insecta Coenagrionidae Megalagrion spp. pinao ‘ula — End — (p)2 2007(a) 2008(a)

Osteichthyes Eleotridae Eleotris sandwicensis ‘o‘opu ‘akupa NG2 End — — — —

Osteichthyes Gobiidae Stenogobius hawaiiensis ‘o‘opu naniha NG2 End — — — —

Osteichthyes Gobiidae Awaous guamensis ‘o‘opu näkea NG1 Ind 1961(p) (p)2 — —

Osteichthyes Gobiidae Sicyopterus stimpsoni ‘o‘opu nöpili NG1 End 1961(p) (p)2 — 2008(?)

Osteichthyes Gobiidae Lentipes concolor ‘o‘opu ‘alamo‘o NG1 End — — — 2008(?)

Osteichthyes Kuhliidae Kuhlia xenura3 äholehole NG2 End — (p)2 — —

1

Ford and others (2008).

2

Undated DAR observation from the Atlas of Hawaiian Watersheds and Their Aquatic Resources (Parham and others, 2008).

3

Revised name for species previously identified as K. sandvicensis.
Damselfly), and M. nigrohamatum nigrohamatum (Blackburn, 

1884) (Blackhook Hawaiian Damselfly).

Life-History Characteristics of Native Species

A number of life-history characteristics factor into 

the habitat selection of native stream fauna in Hawai‘i 

(summarized in Fitzsimons and others, 2007). First, having 

evolved from marine ancestors, the species of interest for this 

study are all amphidromous, retaining a marine larval stage 

(McDowall, 1993; McDowall, 2003). Amphidromy is a type 

of diadromy, which is a life-history type that requires fauna 

to migrate between freshwater and saltwater. Females deposit 

their eggs in streams, the eggs hatch, and the larvae are carried 

downstream to the ocean, where they live as zooplankton for 

a species-specific period of time. They then migrate back to 

freshwater and metamorphose into postlarvae commonly called 

hinana. The postlarvae then make their way upstream, where 

they eventually mature into adults and live for the remainder 

of their lives (Ego, 1956; Tomihama, 1972; Ford and Kinzie, 

1982; Kinzie and Ford, 1982; Kinzie, 1988; McDowall, 1988; 

Radtke and others, 1988; Tate and others, 1992; Radtke and 

others, 2001; McRae, 2007a). For these Hawaiian species, 

unlike salmon, no evidence indicates that the postlarvae recruit 

back to their natal streams. The amphidromous life cycle 

requires unimpeded access to and from the ocean.

Another relevant life-history characteristic is the upstream 

migratory ability of the different species. Four of the five ‘o‘opu 

(‘o‘opu ‘alamo‘o, ‘o‘opu nōpili, ‘o‘opu nākea, and ‘o‘opu naniha) 

are true gobies and have fused pelvic fins. The fused pelvic fin 

forms a suction disk that enables these fishes to attach themselves 

to stream substrate and climb cascades and waterfalls (Kinzie and 

Ford, 1982; Schoenfuss and Blob, 2003; Blob and others, 2006). 

Differences in clinging and climbing abilities have allowed the 

native fish species to migrate upstream and inhabit stream reaches 

according to their relative abilities to cling to the stream substrate. 

‘O‘opu ‘akupa is not a true goby and lacks the fused pelvic fin 

and, therefore, is restricted to the lowest stream reaches, stream 

mouths, and estuaries. ‘O‘opu naniha has the weakest climbing 

ability of the true gobies and also is confined to the lower stream 

reaches, stream mouths, and estuaries. ‘O‘opu nākea, the largest 

of the native fish species, is a moderate climber and commonly 

is found in lower and middle stream reaches. ‘O‘opu nōpili often 

inhabits the middle stream reaches, whereas ‘o‘opu ‘alamo‘o, 

the best climber of the native fish species, typically is found in 

middle and upper stream reaches (Nishimoto and Fitzsimons, 

1986; Fitzsimons and Nishimoto, 1990; Kinzie, 1990). The 

mountain ‘ōpae, ‘ōpaekala‘ole, has exceptional climbing ability 

and most often inhabits the upper stream reaches (Couret, 1976; 

Kinzie, 1990). Hïhïwai generally inhabit lower and middle stream 

reaches, preferring cold, well-oxygenated waters (Ford, 1979; 

Kinzie, 1990). Hapawai and ‘ōpae ‘oeha‘a are restricted to the 

lower stream reaches and estuaries. Segregation along elevation 

and longitudinal gradients reduces the amount of competition 

among native species for resources. Exceptions to the general 

segregation along elevation and longitudinal gradients, however, 

are known to exist. For example, adult ‘o‘opu nōpili were 

commonly observed near the mouth of Waihe‘e River during 

this study. The reasons these ‘o‘opu nōpili do not migrate farther 

upstream are unknown. 

Another factor in habitat selection involves territoriality. 

Mature ‘o‘opu ‘alamo‘o males have been observed to 

aggressively defend territories against male conspecifics (males 

of the same species), whereas females tend to move freely 

about the stream (Lau, 1973; Maciolek, 1977; Nishimoto and 

Fitzsimons, 1986; Fitzsimons and Nishimoto, 1991). Similarly, 

male ‘o‘opu nōpili aggressively defend territories, with larger 

fish defending larger territories (Fitzsimons and Nishimoto, 

1990; Fitzsimons and others, 1993). The normally docile ‘o‘opu 

nākea exhibits aggressive territoriality toward conspecifics 

as well as other species during the fall spawning season 

(Fitzsimons and Nishimoto, 1990).

Dietary preferences of the stream fauna also can influence 

habitat selection. The heterogeneous nature of streams may 

make it possible for species to occupy the same stream 

macrohabitats, because microhabitats commonly have different 

dietary resources. Morphological adaptations of the fishes may 

have functionally served to reduce interspecific competition 

for resources and allow the fish species to coexist (Kido, 1996, 

1997a,b). Heterogeneous algal and invertebrate assemblages in 

Hawaiian streams provide a diversity of dietary resources for 

fish species of various age classes to utilize.

Non-Native Species

Over the years, many non-native species have been 

introduced into Hawaiian streams. More than 50 aquatic animal 

species, excluding insects, have become established in Hawai‘i 

(Brock, 1960; Kanayama, 1967; Maciolek, 1984; Devick, 1991; 

Brasher and others, 2006). The list of non-native species observed 

in Nā Wai ‘Ehā streams include: Thiaridae snails, including the 

red rimmed melania, Melanoides tuberculata (Müller, 1774), 

and the quilted melania, Tarebia granifera (Lamarck, 1822); 

Physidae pouch snail species, Physa Draparnaud, 1801; the 

Asiatic clam, Corbicula fluminea (Müller, 1774); crustaceans, 

including the amphidromous Tahitian prawn, Macrobrachium 

lar (Fabricius, 1798), and the Louisiana crayfish, Procambarus 

clarkii (Girard, 1852); fish from the family Poeciliidae, 

including the western mosquitofish, Gambusia affinis (Baird 

and Girard, 1853), guppies, Poecilia reticulata Peters, 1859, 

and green swordtails, Xiphophorus helleri Heckel, 1848; the 

Chinese catfish, Clarias fuscus (Lacepède, 1803), and the 

Channel catfish, Ictalurus punctatus (Rafinesque, 1818) 

(tables 7–10). Some of these species, such as G. affinis, were 

intentionally released for mosquito control, whereas others, 

such as Physa spp., may be accidental introductions from 

home aquaria (Van Dine, 1907; Devick, 1991; Yamamoto 

and Tagawa, 2000; Cowie, 2000). Some of these species, 

such as the catfish, can directly affect the native fauna by 

Stream Fauna 19
20 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄

Table 7. Non-native aquatic species observed in Waiheÿe River from surveys during 1978–2008, Maui, Hawaiÿi.

[HSA, Hawaiÿi Stream Assessment (Hawaiÿi Cooperative Park Service Unit, 1990); DAR, Hawaiÿi Department of Land and Natural Resources, Division of 

Aquatic Resources; sp., species place holder for determinations to generic level only; spp., more than one species; IG1, introduced species group 1; IG2, introduced species group 2; p, present; a, abundant; va, very abundant;—, no data]

Class Family Genus/Species Common name HSA

classification

Observations

HSA DAR Ford1 This study

Gastropoda Thiaridae Melanoides tuberculata Red rimmed melania IG2 — — — —

Gastropoda Thiaridae Tarebia granifera Quilted melania IG2 — — — —

Gastropoda Physidae Physa spp. Pouch snail IG2 — 2008(p)2 — 2008(a)

Gastropoda Planorbidae Planorbella duryi Ramshorn snail IG2 — — — —

Gastropoda Viviparidae Cipangopaludina chinensis Chinese mystery snail IG2 — (p)3 —

Pelecypoda Corbiculidae Corbicula fluminea Asiatic clam IG1 — — — —

Crustacea Cambaridae Procambarus clarkii Louisiana crayfish IG2 — — — —

Crustacea Palaemonidae Macrobrachium lar Tahitian prawn IG2 1978(a) 2008(p)2 2007(p) 2008(a)

Osteichthyes Poeciliidae Gambusia affinis Western mosquitofish IG1 — — — —

Osteichthyes Poeciliidae Poecilia reticulata Guppy IG1 1978(a) — — 2008(va)

Osteichthyes Poeciliidae Xiphophorus helleri Green swordtail IG1 — — — 2008(va)

Osteichthyes Poeciliidae Poecilia sp. Poeciliids IG1 — — — 2008(va)

Osteichthyes Cichlidae Tilapia sp. Tilapia IG1 — — — —

Osteichthyes Ictaluridae Ictalurus punctatus Channel catfish IG2 — (p)3 — —

1

Ford and others (2008).

2

DAR observation (D. Polhemus, written commun., 2009).

3

Undated DAR observation from the Atlas of Hawaiian Watersheds and Their Aquatic Resources (Parham and others, 2008).

Table 8. Non-native aquatic species observed in Waiehu Stream from surveys during 1961–2008, Maui, Hawaiÿi.

[HSA, Hawaiÿi Stream Assessment (Hawaiÿi Cooperative Park Service Unit, 1990); DAR, Hawaiÿi Department of Land and Natural Resources, Division of 

Aquatic Resources; sp., species place holder for determinations to generic level only; spp., more than one species; IG1, introduced species group 1; IG2, introduced species group 2; p, present; a, abundant; va, very abundant;—, no data]

Class Family Genus/Species Common name HSA

classification

Observations

HSA DAR Ford1 This study

Gastropoda Thiaridae Melanoides tuberculata Red rimmed melania IG2 — — — 2008(a)

Gastropoda Thiaridae Tarebia granifera Quilted melania IG2 — 2008(p)2 — 2008(a)

Gastropoda Physidae Physa spp. Pouch snail IG2 — 2008(p)2 — 2008(a)

Gastropoda Planorbidae Planorbella duryi Ramshorn snail IG2 — — — 2008(a)

Gastropoda Ampullariidae Pomacea canaliculata Channeled apple snail IG2 — (p)3 — —

Pelecypoda Corbiculidae Corbicula fluminea Asiatic clam IG1 — 2008(p)2 — —

Crustacea Cambaridae Procambarus clarkii Louisiana crayfish IG2 — (p)3 2007(a) —

Crustacea Palaemonidae Macrobrachium lar Tahitian prawn IG2 — 2008(p)2 2007(p) 2008(a)

Osteichthyes Poeciliidae Gambusia affinis Western mosquitofish IG1 — — 2007(a) —

Osteichthyes Poeciliidae Poecilia reticulata Guppy IG1 — 2008(a)2 — 2008(va)

Osteichthyes Poeciliidae Xiphophorus helleri Green swordtail IG1 — 2008(p)2 — 2008(va)

Osteichthyes Poeciliidae Poecilia sp. Poeciliids IG1 — 2008(p)2 — 2008

Osteichthyes Cichlidae Tilapia sp. Tilapia IG1 — — — —

Osteichthyes Clariidae Clarias fuscus Chinese catfish IG2 — (p)3 — —

1

Ford and others (2008).

2

DAR observation (D. Polhemus, written commun., 2009).

3

Undated DAR observation from the Atlas of Hawaiian Watersheds and Their Aquatic Resources (Parham and others, 2008).
Table 9. Non-native aquatic species observed in ÿI

−

ao Stream from surveys during 1961–2008, Maui, Hawaiÿi.

[HSA, Hawaiÿi Stream Assessment (Hawaiÿi Cooperative Park Service Unit, 1990); DAR, Hawaiÿi Department of Land and Natural Resources, Division of 

Aquatic Resources; sp., species place holder for determinations to generic level only; spp., more than one species; IG1, introduced species group 1; IG2, introduced species group 2; p, present; a, abundant; va, very abundant; —, no data]

Class Family Genus/Species Common name HSA

classification

Observations

HSA DAR Ford1 This study

Gastropoda Thiaridae Melanoides tuberculata Red rimmed melania IG2 — — — 2008(a)

Gastropoda Thiaridae Tarebia granifera Quilted melania IG2 — — — 2008(a)

Gastropoda Physidae Physa spp. Pouch snail IG2 — (p)2 2007(a) 2008(a)

Gastropoda Planorbidae Planorbella duryi Ramshorn snail IG2 — — — 2008(a)

Pelecypoda Corbiculidae Corbicula fluminea Asiatic clam IG1 — — — —

Crustacea Cambaridae Procambarus clarkii Louisiana crayfish IG2 — — — —

Crustacea Palaemonidae Macrobrachium lar Tahitian prawn IG2 1989(p) (p)2 2007 (p) 2008(a)

Osteichthyes Poeciliidae Gambusia affinis Western mosquitofish IG1 1989(p) (p)2 — —

Osteichthyes Poeciliidae Poecilia reticulata Guppy IG1 — (p)2 2007(va) 2008(va)

Osteichthyes Poeciliidae Xiphophorus helleri Green swordtail IG1 — (p)2 — 2008(va)

Osteichthyes Poeciliidae Poecilia sp. Poeciliids IG1 — (p)2 2007(va) 2008(va)

Osteichthyes Cichlidae Tilapia sp. Tilapia IG1 — (p)2 — —

Osteichthyes Ictaluridae Ictalurus punctatus Channel catfish IG2 — — — —

1

Ford and others (2008).

2

Undated DAR observation from the Atlas of Hawaiian Watersheds and Their Aquatic Resources (Parham and others, 2008). 

Table 10. Non-native aquatic species observed in Waikapu− Stream from surveys during 1961–2008, Maui, Hawaiÿi.

[HSA, Hawaiÿi Stream Assessment (Hawaiÿi Cooperative Park Service Unit, 1990); DAR, Hawaiÿi Department of Land and Natural Resources, Division of 

Aquatic Resources; sp., species place holder for determinations to generic level only; spp., more than one species; IG1, introduced species group 1; IG2, introduced species group 2; p, present; a, abundant;—, no data]

Class Family Genus/Species Common name HSA

classification

Observations

HSA DAR Ford1 This study

Gastropoda Thiaridae Melanoides tuberculata Red rimmed melania IG2 — (p)2 — —

Gastropoda Thiaridae Tarebia granifera Quilted melania IG2 — — — —

Gastropoda Physidae Physa spp. Pouch snail IG2 — — 2008(p) 2008(a)

Gastropoda Planorbidae Planorbella duryi Ramshorn snail IG2 — — — —

Pelecypoda Corbiculidae Corbicula fluminea Asiatic clam IG1 — (p)2 2008(p) —

Crustacea Cambaridae Procambarus clarkii Louisiana crayfish IG2 — (p)2 2007(p) 2008(a)

Crustacea Palaemonidae Macrobrachium lar Tahitian prawn IG2 — — — —

Osteichthyes Poeciliidae Gambusia affinis Western mosquitofish IG1 — (p)2 — —

Osteichthyes Poeciliidae Poecilia reticulata Guppy IG1 — — 2007(a) —

Osteichthyes Poeciliidae Xiphophorus helleri Green swordtail IG1 — — — —

Osteichthyes Poeciliidae Poecilia sp. Poeciliids IG1 — — — —

Osteichthyes Cichlidae Tilapia sp. Tilapia IG1 — (p)2 — —

Osteichthyes Ictaluridae Ictalurus punctatus Channel catfish IG2 — (p)2 — —

1

Ford and others (2008).

2

Undated DAR observation from the Atlas of Hawaiian Watersheds and Their Aquatic Resources (Parham and others, 2008).

Stream Fauna 21
preying on small fishes, crustaceans, and insects (Yamamoto 

and Tagawa, 2000). The HSA classified non-native species 

into two groups based on their potential to threaten native 

species (Hawai‘i Cooperative Park Service Unit, 1990). Nonnative species group 1 (IG1) included non-native species that 

threaten native species by predation or competition. Nonnative species group 2 (IG2) included non-native species that 

are not harmful to native species.

Aquatic Fauna in Na ̄ Wai ÿEha ̄ Streams

As part of this study, the presence or absence and 

distribution of aquatic species were determined using snorkel 

surveys at selected reaches on Nā Wai ‘Ehā streams during 

2008 (tables 3–10; figs. 9–15). In conducting these surveys, a 

snorkeler entered the stream below the downstream end of 

the reach and slowly moved upstream and photographed and 

identified the observed fish, snail, and crustacean species. 

Locations of the observations were recorded with a GPS 

(global positioning system) unit. The presence of hïhïwai was 

determined by sight and by overturning and inspecting rocks 

while snorkeling. Adult native damselflies, pinao ‘ula, of the 

endemic genus Megalagrion also were photographed and 

identified. Additional observations of the aquatic biota were 

made throughout the study period at various locations along 

the Nā Wai ‘Ehā streams to provide supplemental information 

on the distribution of the aquatic fauna.

Native Species

Each of the four streams has different natural and 

human-influenced conditions affecting the ability of the 

amphidromous native stream fauna to recruit, colonize, and 

flourish along the length of the stream. The amphidromous 

life cycle requires stream connectivity to the ocean to 

enable recruitment, and any condition that impedes that 

connectivity can affect the distribution and abundance of the 

amphidromous fauna.

Waiheÿe River

The Timbol and Maciolek (1978) inventory listed 

Waihe‘e River as having five diversions and five road crossings. 

In 1990, the Hawai‘i Stream Assessment (HSA), a cooperative 

project that attempted to identify streams and rivers in Hawai‘i 

with significant native aquatic biodiversity, rated Waihe‘e River 

as having “Outstanding” aquatic resources and “Good” native 

diversity (Hawai‘i Cooperative Park Service Unit, 1990). The 

HSA aquatic biota surveys of Waihe‘e River included three 

Native Group 1 (NG1) species (“indicator species” considered 

representative of potentially high-quality stream ecosystems), 

‘o‘opu ‘alamo‘o, ‘o‘opu nōpili, and ‘o‘opu nākea, and one Native 

Group 2 (NG2) species (species considered more common and 

typical of a healthy native stream ecosystem), ‘ōpaekala‘ole. 

Data from Hawai‘i Department of Land and Natural Resources, 

Division of Aquatic Resources (DAR) point-quadrat surveys 

(Baker and Foster, 1992) conducted in Waihe‘e River in 1995 

identified ‘ōpaekala‘ole, ‘o‘opu ‘alamo‘o, ‘o‘opu nōpili, ‘o‘opu 

nākea, and hïhïwai (State of Hawai‘i, 2004). More recently, Ford 

and others (2008) observed ‘ōpaekala‘ole and ‘o‘opu ‘alamo‘o 

in the upper reaches (altitude 1,600 ft) and ‘ōpaekala‘ole, 

‘o‘opu ‘alamo‘o, ‘o‘opu nōpili, and ‘o‘opu nākea in the middle 

(420–620 ft) and lower (100 ft) reaches. DAR point-quadrat 

surveys conducted in 2008 also identified ‘ōpaekala‘ole, ‘o‘opu 

‘alamo‘o, ‘o‘opu nōpili, and ‘o‘opu nākea in Waihe‘e River (D. 

Polhemus, written commun., 2009). Stream surveys conducted by 

the USGS in 2008, as part of this study, identified ‘ōpaekala‘ole, 

‘o‘opu ‘alamo‘o, ‘o‘opu nōpili, ‘o‘opu nākea, ‘o‘opu ‘akupa, and 

āholehole at various locations along Waihe‘e River (figs. 9–13). 

Waihe‘e River also has been the site of stream fauna studies 

involving benthic macroinvertebrate assemblages (McIntosh and 

others, 2008).

Waiehu Stream

The Timbol and Maciolek (1978) inventory listed Waiehu 

Stream as having five diversions and eight road crossings. The 

HSA determined Waiehu Stream as having “Substantial” aquatic 

resources and “Good” native diversity, including two NG1 

species, ‘o‘opu nōpili and ‘o‘opu nākea, and one NG2 species, 

‘ōpaekala‘ole (Hawai‘i Cooperative Park Service Unit, 1990). 

More recently, DAR point-quadrat surveys conducted in 2008 

identified ‘ōpaekala‘ole, ‘o‘opu ‘alamo‘o, ‘o‘opu nōpili, and 

‘o‘opu nākea in Waiehu Stream (D. Polhemus, written commun., 

2009). The DAR “Atlas of Hawaiian Watersheds and Their 

Aquatic Resources” also has records of ‘o‘opu ‘akupa, hapawai, 

hïhïwai, and āholehole in the Waiehu watershed (Parham and 

others, 2008). Ford and others (2008) observed ‘ōpaekala‘ole, 

‘o‘opu ‘alamo‘o, and ‘o‘opu nākea in North Waiehu Stream at an 

altitude of 875 ft and ‘o‘opu nōpili downstream of an altitude of 

100 ft. Stream surveys conducted by the USGS in 2008, as part of 

this study, identified ‘ōpaekala‘ole, ‘o‘opu ‘alamo‘o, ‘o‘opu nōpili, 

‘o‘opu nākea, and āholehole at various locations along Waiehu 

Stream (figs. 9–13).

ÿĪao Stream

The Timbol and Maciolek (1978) inventory listed ‘Īao 

Stream as having nine diversions and six road crossings. 

The HSA rated ‘Īao Stream as having “Substantial” aquatic 

resources and “Excellent” native diversity (Hawai‘i Cooperative 

Park Service Unit, 1990). The HSA aquatic biota surveys of ‘Īao 

Stream included two NG1 species, ‘o‘opu nōpili and ‘o‘opu 

nākea, and two NG2 species, ‘ōpaekala‘ole and āholehole. 

Data from the DAR Freshwater Database (State of Hawai‘i, 

2004) recorded in 1994 observations of ‘ōpaekala‘ole and 

‘o‘opu ‘alamo‘o in Po‘onāhoahoa Stream and ‘ōpaekala‘ole 

and ‘o‘opu nākea in Nākalaloa Stream, both tributaries of ‘Īao 

22 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
EXPLANATION

NATIVE STREAM FAUNA--

 ÿOÿOPU ÿALAMOÿO (Lentipes concolor)

 SPECIES OBSERVED

 SPECIES NOT OBSERVED

Waiheÿe River

ÿÏao Stream

Waiehu Stream

Waikapü Stream

0 0.5 1 MILES

0 0.5 1 KILOMETERS

Base modified from U.S. Geological Survey Digital Raster

Graphics topographic map, 1:24,000 scale, Universal 

Transverse Mercator projection, zone 4, NAD83 datum.

156°34' 156°32' 156°30' 156°28'

20°56'

20°54'

20°52'

Figure 9. Distribution of ÿoÿopu ÿalamoÿo (Lentipes concolor, shown in inset photograph) from stream surveys during 

August and September 2008, Na ̄ Wai ÿEha ̄, Maui, Hawaiÿi.

Stream Fauna 23
EXPLANATION

NATIVE STREAM FAUNA--

 ÿOÿOPU NÖPILI (Sicyopterus stimpsoni)

 SPECIES OBSERVED

 SPECIES NOT OBSERVED

Waiheÿe River

ÿÏao Stream

Waiehu Stream

Waikapü Stream

0 0.5 1 MILES

0 0.5 1 KILOMETERS

Base modified from U.S. Geological Survey Digital Raster

Graphics topographic map, 1:24,000 scale, Universal 

Transverse Mercator projection, zone 4, NAD83 datum.

156°34' 156°32' 156°30' 156°28'

20°56'

20°54'

20°52'

Figure 10. Distribution of ÿoÿopu no ̄pili (Sicyopterus stimpsoni, shown in inset photograph) from stream surveys during 

August and September 2008, Na ̄ Wai ÿEha ̄, Maui, Hawaiÿi.

24 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
EXPLANATION

NATIVE STREAM FAUNA--

 ÿOÿOPU NÄKEA (Awaous guamensis)

 SPECIES OBSERVED

 SPECIES NOT OBSERVED

Waiheÿe River

ÿÏao Stream

Waiehu Stream

Waikapü Stream

0 0.5 1 MILES

0 0.5 1 KILOMETERS

Base modified from U.S. Geological Survey Digital Raster

Graphics topographic map, 1:24,000 scale, Universal 

Transverse Mercator projection, zone 4, NAD83 datum.

156°34' 156°32' 156°30' 156°28'

20°56'

20°54'

20°52'

Figure 11. Distribution of ÿoÿopu na ̄kea (Awaous guamensis, shown in inset photograph) from stream surveys during 

August and September 2008, Na ̄ Wai ÿEha ̄, Maui, Hawaiÿi.

Stream Fauna 25
EXPLANATION

NATIVE STREAM FAUNA--

 ‘ÖPAEKALA‘OLE (Atyoida bisulcata)

 SPECIES OBSERVED

 SPECIES NOT OBSERVED

Waiheÿe River

ÿÏao Stream

Waiehu Stream

Waikapü Stream

0 0.5 1 MILES

0 0.5 1 KILOMETERS

Base modified from U.S. Geological Survey Digital Raster

Graphics topographic map, 1:24,000 scale, Universal 

Transverse Mercator projection, zone 4, NAD83 datum.

156°34' 156°32' 156°30' 156°28'

20°56'

20°54'

20°52'

Figure 12. Distribution of ÿöpaekalaÿole (Atyoida bisulcata, shown in inset photograph) from stream surveys during 

August and September 2008, Na ̄ Wai ÿEha ̄, Maui, Hawaiÿi.

26 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
EXPLANATION

NATIVE STREAM FAUNA

 ‘O‘OPU ‘AKUPA (Eleotris sandwicensis)

 ‘O‘OPU (unidentified adult)

 ‘O‘OPU (unidentified recruits)

 ÄHOLEHOLE (Kuhlia xenura)

 

Waiheÿe River

ÿÏao Stream

Waiehu Stream

Waikapü Stream

0 0.5 1 MILES

0 0.5 1 KILOMETERS

Base modified from U.S. Geological Survey Digital Raster

Graphics topographic map, 1:24,000 scale, Universal 

Transverse Mercator projection, zone 4, NAD83 datum.

156°34' 156°32' 156°30' 156°28'

20°56'

20°54'

20°52'

Figure 13. Selected native stream fauna, including ÿoÿopu ÿakupa (Eleotris sandwicensis, shown in upper inset photograph), äholehole (Kuhlia xenura, shown in lower inset photograph), and unidentified ÿoÿopu, observed during 2008, Na ̄ 

Wai ÿEha ̄, Maui, Hawaiÿi.

Stream Fauna 27
EXPLANATION

NON-NATIVE STREAM FAUNA

 TAHITIAN PRAWN (Macrobrachium lar)

 CRAYFISH (Procambarus clarkii)

 NEITHER TAHITIAN PRAWN NOR

 CRAYFISH OBSERVED

 

Waiheÿe River

ÿÏao Stream

Waiehu Stream

Waikapü Stream

0 0.5 1 MILES

0 0.5 1 KILOMETERS

Base modified from U.S. Geological Survey Digital Raster

Graphics topographic map, 1:24,000 scale, Universal 

Transverse Mercator projection, zone 4, NAD83 datum.

156°34' 156°32' 156°30' 156°28'

20°56'

20°54'

20°52'

Figure 14. Distribution of Tahitian prawn (Macrobrachium lar, shown in upper inset photograph) and crayfish (Procambarus clarkii, 

shown in lower inset photograph) from stream surveys during August and September 2008, Nä Wai ÿEhä, Maui, Hawaiÿi.

Figure 14. Distribution of Tahitian prawn (Macrobrachium lar, shown in upper inset photograph) and crayfish (Procambarus clarkii, shown in lower inset photograph) from stream surveys during August and September 2008, Na ̄ Wai 

ÿEha ̄, Maui, Hawaiÿi.

28 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
EXPLANATION

NON-NATIVE STREAM FAUNA

 GUPPY (Poecilia reticulata)

 GREEN SWORDTAIL (Xiphophorus helleri)

 NEITHER GUPPY NOR GREEN 

 SWORDTAIL OBSERVED

 

Waiheÿe River

ÿÏao Stream

Waiehu Stream

Waikapü Stream

0 0.5 1 MILES

0 0.5 1 KILOMETERS

Base modified from U.S. Geological Survey Digital Raster

Graphics topographic map, 1:24,000 scale, Universal 

Transverse Mercator projection, zone 4, NAD83 datum.

156°34' 156°32' 156°30' 156°28'

20°56'

20°54'

20°52'

Figure 15. Distribution of green swordtails (Xiphophorus helleri, shown in upper inset photograph) and guppies (Poecilia reticulata, 

shown in lower inset photograph) from stream surveys during August and September 2008, Nä Wai ÿEhä, Maui, Hawaiÿi.

Figure 15. Distribution of green swordtails (Xiphophorus helleri, shown in upper inset photograph) and guppies 

(Poecilia reticulata, shown in lower inset photograph) from stream surveys during August and September 2008, Na ̄ Wai 

ÿEha ̄, Maui, Hawaiÿi.

Stream Fauna 29
Stream, during point-quadrat count surveys. The DAR “Atlas 

of Hawaiian Watersheds and Their Aquatic Resources” also has 

records of ‘o‘opu naniha, ‘o‘opu ‘akupa, and āholehole in the 

‘Īao watershed (Parham and others, 2008). In 2007, Ford and 

others (2008) observed ‘ōpaekala‘ole, ‘o‘opu ‘alamo‘o, and 

‘o‘opu nōpili in the upper reaches (1,600 ft) and ‘ōpaekala‘ole, 

‘o‘opu ‘alamo‘o, ‘o‘opu nōpili, and ‘o‘opu nākea in the 

middle reaches (760–1,200 ft) of ‘Īao Stream. Stream surveys 

conducted by the USGS in 2008, as part of this study, identified 

‘ōpaekala‘ole, ‘o‘opu ‘alamo‘o, ‘o‘opu nōpili, and ‘o‘opu nākea 

at various locations along ‘Īao Stream (figs. 9–13).

‘Īao Stream has been the site of many stream fauna 

studies involving (1) recruitment of hïhïwai (Hau, 2007), 

‘o‘opu (State of Hawai‘i, 2000; Benbow, 2001; Benbow and 

others, 2004a,b), and ‘ōpaekala‘ole (Benbow and others, 

2004a); (2) migration of hïhïwai (Benbow, 2001; Jennings 

and others, 2002); and (3) benthic macroinvertebrate 

assemblages (McIntosh and others, 2002, 2003; Benbow and 

others, 2003, 2005).

Waikapü Stream

The Timbol and Maciolek (1978) inventory listed 

Waikapū Stream as having nine diversions and nine road 

crossings. The HSA determined Waikapū Stream as having 

“Substantial” aquatic resources and “Good” native diversity, 

including two NG1 species, ‘o‘opu nōpili and ‘o‘opu nākea, 

and one NG2 species, ‘ōpaekala‘ole (Hawai‘i Cooperative 

Park Service Unit, 1990). The DAR “Atlas of Hawaiian 

Watersheds and Their Aquatic Resources” also has records 

of ‘ōpaekala‘ole, ‘ōpae ‘oeha‘a, ‘o‘opu nōpili, ‘o‘opu nākea, 

āholehole, and hapawai in the Waikapū watershed (Parham 

and others, 2008). More recently, Ford and others (2008) 

observed ‘ōpaekala‘ole near an altitude of 1,180 ft, upstream 

and downstream of the South Side Ditch intake, and no native 

species at and downstream of an altitude of 410 ft. Stream 

surveys conducted by the USGS in 2008, as part of this study, 

identified ‘ōpaekala‘ole at various locations along Waikapū 

Stream (figs. 9–13). A juvenile ‘o‘opu also was observed and 

photographed by the USGS in the pool just downstream of 

the South Side Ditch intake (fig. 13) during April 2008 and 

was identified as either ‘o‘opu ‘alamo‘o or ‘o‘opu nōpili (D.P. 

Lindstrom, oral commun., 2009).

Non-Native Species

The Nā Wai ‘Ehā streams have a number of non-native 

aquatic species (tables 7–10; figs. 14–15). Non-native 

species have been introduced into Hawaiian streams either 

purposefully, with or without government sponsorship, for 

reasons such as mosquito control, weed control, fishing, food, 

or for ornamental ponds, or accidentally by escaping from 

aquaculture facilities, being brought in with aquatic plants or 

ballast water, or being released from home aquaria (Brock, 

1960; Kanayama, 1967; Maciolek, 1984; Devick, 1991; 

Yamamoto and Tagawa, 2000).

Waiheÿe River

HSA surveys of Waihe‘e River in 1978 included records 

of the IG1 species Poecilia reticulata and the IG2 species the 

Tahitian prawn (Hawai‘i Cooperative Park Service Unit, 1990). 

DAR point-quadrat surveys conducted in Waihe‘e River in 

1995 identified the Tahitian prawn (State of Hawai‘i, 2004). 

DAR point-quadrat surveys conducted in 2008 identified the 

Tahitian prawn and non-native Physidae (D. Polhemus, written 

commun., 2009). The “Atlas of Hawaiian Watersheds and Their 

Aquatic Resources” also has records of the Chinese mystery 

snail, Cipangopaludina chinensis (Gray, 1834), in the Waihe‘e 

watershed (Parham and others, 2008). Ford and others (2008) 

observed no non-native fauna in the upper reaches (1,600 ft) 

and the Tahitian prawn in the middle (420–620 ft) and lower 

(100 ft) reaches. Stream surveys conducted by the USGS in 

2008, as part of this study, identified guppies, green swordtails, 

Physidae snails, and the Tahitian prawn at various locations 

along Waihe‘e River (figs. 14–15).

Waiehu Stream

HSA surveys of Waiehu Stream in 1961 had no records 

of non-native species (Hawai‘i Cooperative Park Service Unit, 

1990). DAR point-quadrat surveys conducted in 2008 identified 

green swordtails, guppies, the Tahitian prawn, and non-native 

mollusks, including the Asiatic clam, Tarebia granifera, and 

Physidae species (D. Polhemus, written commun., 2009). 

In addition to these observations, the “Atlas of Hawaiian 

Watersheds and Their Aquatic Resources” also has records of 

the Louisiana crayfish and the Chinese catfish (Parham and 

others, 2008). Ford and others (2008) observed the Tahitian 

prawn in North Waiehu Stream at an altitude of 875 ft and the 

western mosquitofish, the Louisiana crayfish, and the Tahitian 

prawn downstream of an altitude of 100 ft. Stream surveys 

conducted by the USGS in 2008, as part of this study, identified 

guppies, green swordtails, and the Tahitian prawn at various 

locations along Waiehu Stream (figs. 14–15).

ÿĪao Stream

HSA surveys of ‘Īao Stream in 1989 included records of 

the IG1 species the western mosquitofish and the IG2 species 

the Tahitian prawn (Hawai‘i Cooperative Park Service Unit, 

1990). In addition to these species, the “Atlas of Hawaiian 

Watersheds and Their Aquatic Resources” also has records 

of guppies, green swordtails, a species of tilapia, Physidae 

snail species, and other non-native snails in the ‘Īao watershed 

(Parham and others, 2008). No non-native species were 

30 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
recorded during DAR point-quadrat surveys conducted in 

‘Īao Stream in 1994 (State of Hawai‘i, 2004). Stream surveys 

conducted by the USGS in 2008, as part of this study, identified 

guppies, green swordtails, the Tahitian prawn, Physidae snails, 

Thiaridae snails, and ramshorn snails at various locations along 

‘Īao Stream (figs. 14–15). During 2006, the USGS observed 

and photographed a turtle identified as a red-eared slider, 

Chrysemys scripta elegans (Wied-Neuwied, 1839), near an 

altitude of 570 ft. The red-eared slider is a common pet species 

that has become established at locations on Oahu (Yamamoto 

and Tagawa, 2000).

Waikapu ̄ Stream

HSA surveys of Waikapū Stream in 1961 had no 

records of non-native species (Hawai‘i Cooperative Park 

Service Unit, 1990). The “Atlas of Hawaiian Watersheds 

and Their Aquatic Resources” has records of the Asiatic 

clam, the Louisiana crayfish, the western mosquitofish, the 

Chinese catfish, and a species of tilapia. Ford and others 

(2008) observed the Louisiana crayfish and a Lymnaeid snail 

species near an altitude of 1,180 ft, the Louisiana crayfish 

and guppies near an altitude of 410 ft, and the Asiatic 

clam and Physidae snails near an altitude of 200 ft. Stream 

surveys conducted by the USGS in 2008, as part of this 

study, identified the Louisiana crayfish and Physidae snails at 

various locations along Waikapū Stream (fig. 14).

Potential Factors Affecting Abundances of 

Native Species

The availability of physical habitat and water 

temperature may affect the abundance of native species in 

Nā Wai ‘Ehā streams. The relations between streamflow 

and physical habitat for selected native species and 

measured stream temperatures along Nā Wai ‘Ehā streams 

are described in later sections of this report. In addition to 

physical habitat and temperature, other factors that may 

affect the abundance of native species in Nā Wai ‘Ehā 

streams include, but are not limited to, the presence of nonnative species, channelization, water removal, and land-use 

activities in areas adjacent to the stream (Brasher, 2003).

Waiheÿe River

The intakes for the Waihe‘e Ditch are steel grates that are 

capable of diverting all of the dry-weather flow of Waihe‘e 

River. Water being diverted into the intake grates can create 

a tremendous downward force on the small, bottom-dwelling 

fish and shrimp that attempt to traverse the grate. Postlarvae 

recruits may become entrained in the diverted water and 

subsequently constrained to move within the ditch system to 

points of discharge. Larval ‘o‘opu, ‘ōpae, and hïhïwai heading 

downstream to the ocean also may become entrained in the 

diverted water, removing them from the gene pool (Benstead 

and others, 1999). All diversion intakes similar to the Waihe‘e 

Ditch intakes can affect the abundances of native species.

In its natural state, using the ecosystem classification 

developed by Polhemus and others (1992), Waihe‘e River 

would be classified as a continuous perennial stream, but 

because of the diversion of surface water it is classified as 

an artificially interrupted perennial stream. Stream reaches 

downstream of the Waihe‘e and Spreckels Ditch intakes 

sometimes were dry during the course of this study. These dry 

reaches can impede the upstream migration of amphidromous 

species. Adult ‘o‘opu must find cool, persistent pools during 

dry-weather periods or perish.

Waiehu Stream

A potential factor affecting the distribution and abundance 

of native aquatic biota in Waiehu Stream is the diversion 

of water for offstream uses. In its natural state, this stream 

mainly would be classified as a continuous perennial stream, 

but because of the diversion of surface water it is classified 

as an artificially interrupted perennial stream. The upstream 

water removal causes the stream to be dry at lower altitudes, 

which affects the timing and duration of stream connectivity 

to the ocean and consequently limits the opportunity for the 

amphidromous species to successfully recruit and migrate 

upstream. Adult ‘o‘opu may perish in isolated pools because of 

elevated temperatures or insufficient dissolved oxygen (fig. 16). 

The vertical wall (about 10 to 15 ft high) of the Spreckels Ditch 

diversion structure on South Waiehu Stream (fig. 17) also could 

impede the upstream migration of the amphidromous species.

ÿĪao Stream

Two factors that potentially affect the distribution and 

abundance of native fauna in ‘Īao Stream are: (1) diversions 

that commonly cause some stream reaches to be dry, and (2) 

the sections of modified, concrete-lined stream channel. These 

two factors interact to affect the timing and duration of stream 

connectivity to the ocean and consequently limit the opportunity 

for the amphidromous species postlarvae to successfully recruit 

and migrate upstream (Hau, 2007). In its natural state, ‘Īao 

Stream would be classified as a continuous perennial stream, 

flowing continuously to the ocean over its entire course, but 

the diversions have changed the classification to that of an 

artificially interrupted perennial stream, with dry reaches 

downstream of diversions. The common intake for the ‘ĪaoWaikapū and ‘Īao-Māniania Ditches commonly diverts all of the 

dry-weather flow of ‘Īao Stream. Two sections of ‘Īao Stream 

currently are lined with concrete. Between altitudes of about 

310 and 220 ft, ‘Īao Stream consists of a 1,100-ft-long concretelined channel with several chutes and a vertical drop structure 

(fig. 18), about 20 ft high, near the downstream end of the reach 

(Lencioni, 2000). From an altitude of about 35 ft down to its 

Stream Fauna 31
mouth, ‘Īao Stream consists of a 1,700-ft-long concrete-lined 

channel (fig. 19).

‘Īao Stream flows to the ocean only during periods of 

moderate or heavy rainfall or ditch maintenance, when water 

is returned to the stream. This temporary connectivity can end 

abruptly, because the concrete channel was engineered as a 

flood control project meant to quickly transport the water out 

to the ocean. Larval animals that do not make it successfully to 

the ocean may perish. Migrating postlarvae need to negotiate 

the concrete channel to upstream areas with more persistent 

flow in order to survive. On a number of occasions since 2005, 

USGS personnel observed recruiting ‘o‘opu and ‘ōpaekala‘ole 

in small, disconnected puddles in the concrete channel near 

the stream mouth. As these puddles heat up in the sun and 

evaporate, the postlarvae recruits die (fig. 19). Even in stream 

reaches with natural channels, downstream of the intake for the 

‘Īao-Waikapū and ‘Īao-Māniania Ditches, the ‘o‘opu must find 

cool, persistent pools during dry-weather periods or perish.

Other impediments to upstream migration include a 

vertical drop in the concrete channelized section near an 

altitude of 220 ft (fig. 18), a subvertical drop near an altitude 

of 370 ft upstream of a debris basin (fig. 20), and the gratetype intake structures. Water being diverted into an intake 

grate may entrain postlarvae recruits, removing them from 

the stream, or larval ‘o‘opu, ‘ōpae, and hïhïwai heading 

downstream to the ocean, removing them from the gene pool.

downstream

direction

pool

A

B

Figure 17. Photograph of dam structure just downstream of the Spreckels Ditch 

diversion intake near an altitude of 270 feet, South Waiehu Stream, Maui, Hawaiÿ

(July 17, 2006). 

Figure 16. Photographs of isolated shallow pool of water 

with ÿoÿopu near an altitude of 20 feet, Waiehu Stream, 

Maui, Hawaiÿi. A, Shallow pool at the left (north) edge of the 

channel beneath bridge (June 30, 2006). B, Dead and living 

ÿoÿopu in shallow pool (June 30, 2006).

Figure 17. Photograph of dam structure just downstream 

of the Spreckels Ditch diversion intake near an altitude of 

270 feet, South Waiehu Stream, Maui, Hawaiÿi (July 17, 

2006).

32 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Waikapu ̄ Stream

Unlike the other streams in this study, Waikapū Stream 

flows south and discharges into the Keālia Pond National 

Wildlife Refuge, an important home to endangered native 

wetland birds. Waikapū Stream would be classified as a 

naturally interrupted perennial stream (Polhemus and others, 

1992), with perennial flow in its upper reaches and naturally 

dry lower reaches. Connectivity to Keālia Pond only occurs 

during and following periods of rainfall, and connectivity to 

the ocean also requires Keālia Pond to discharge to the ocean. 

Recruitment and upstream migration to the perennial stream 

reaches may be possible only during extended wet periods, 

when continuous flow to the ocean is maintained for a sufficient 

duration. However, the presence of amphidromous species 

in the perennial reaches may be from human intervention or 

passage through the ditch system, as discussed below.

Artificial Transport of Postlarvae

The Hawai‘i DAR and other individuals have been 

involved with transporting postlarvae recruits, collected from 

stream mouths, to stream reaches upstream of the dry reaches 

of ‘Īao Stream and Waikapū Stream (Polhemus, 2007; Skippy 

Figure 18. Photograph of vertical drop structure in concrete-lined channel near 

an altitude of 220 feet, ÿÏao Stream, Maui, Hawaiÿi (August 13, 2008). 

0

0 1 2 3 4 5 CENTIMETERS

1 2 INCHES

A B

Figure 18. Photograph of vertical drop structure in concrete-lined channel near an altitude of 220 feet, ÿĪao Stream, 

Maui, Hawaiÿi (August 13, 2008).

Figure 19. Photograph of concrete-lined channel of ÿĪao Stream near an altitude of 30 feet, Maui, Hawaiÿi. A, Disconnected 

puddles of water may exist following a period of rainfall (March 17, 2005). B, Migrating postlarvae ÿoÿopu recruits may die in 

these puddles as water temperatures rise to lethal levels (March 17, 2005).

Stream Fauna 33
Hau, written commun., 2009). This artificial transport of recruits 

to enhance upstream populations of native species also may 

increase the reproductive output of the streams and thus increase 

the populations of nearshore postlarvae. However, this effort 

can confound analyses of stream-fauna surveys by artificially 

increasing the abundances of native species in areas upstream of 

existing impediments to migration.

Ditch System

The system of ditches that interconnects the four streams in 

the Nā Wai ‘Ehā area removes water from streams for offstream 

uses. Both native and non-native species have been observed in 

the ditches during the period of this study. These ditches may 

enable some aquatic biota to travel from one stream to another. 

It may be possible for some organisms to enter the ditch system 

from one stream and exit the system into another stream. Within 

the ditch system, this movement can be either in an upstream 

or downstream direction. Similar to the upstream relocation of 

the postlarvae, species movement within the ditch system can 

increase the species abundances in areas upstream of existing 

impediments to migration. The ditch system also may act as a 

conduit that allows some non-native species to move into areas 

they could not otherwise reach.

Larvae and Postlarvae

The system of ditches and ditch intakes efficiently 

diverts surface water for delivery to offstream uses. The 

ditch system also may divert large percentages of larval 

‘o‘opu, ‘ōpae, and hïhïwai that were headed downstream 

to the ocean, removing them from the gene pool (Benstead 

and others, 1999). The ditches prevent the larvae from 

reaching the population of marine-phase larvae, which 

could consequently decrease the number of locally available 

postlarvae recruits. Additionally, reduced streamflow caused 

by diversions results in lower water velocity that potentially 

increases the length of time it takes for larvae to reach the 

ocean, thus increasing the chance that the larvae may die 

from starvation (Lindstrom and Brown, 1996; Iguchi and 

Mizuno, 1999; Iguchi, 2007; McRae, 2007b). These effects 

may function to reduce the contribution of larvae from these 

streams to the nearshore population of potential recruits. The 

removal of the amphidromous larvae by the ditch system and 

the increased mortality caused by reduced streamflow may 

have transformed some of the upstream habitats from source 

habitats to sink habitats (McRae, 2007b).

Another effect of reduced streamflow is a reduction in 

the size of the estuary and the freshwater plume that extends 

into the marine environment. The native amphidromous 

species cue on the freshwater plume to begin their 

recruitment to the stream mouths (Tate and others, 1992). 

Reductions in the size and frequency of the freshwater 

plumes may reduce the overall number of postlarvae recruits 

to the dewatered streams.

Other Issues Not Investigated

Ecosystems in the Nā Wai ‘Ehā streams are composed 

of complex webs of interconnected hydrological, chemical, 

and biological processes. This study only addresses a 

part of the ecological composition. Factors that were not 

investigated during this study include, but are not limited 

to, the reproduction, larval dispersal, and recruitment of the 

amphidromous species; the effects of non-native amphibians 

such as frogs and toads; water chemistry and water-quality 

parameters; parasites; non-native marine species; and benthic 

algal and macroinvertebrate assemblages.

Natural, Undiverted Low-Flow 

Characteristics

Natural, undiverted streamflows can be characterized 

using data from historical and active USGS gaging stations 

(table 11). Data from these stations can be extrapolated to 

other reaches using additional discharge measurements (figs. 

21–24; table 12, placed at the end of the report as appendix 

B) that quantify gains and losses in the stream channels and 

tributary inflows. 

Gaging-Station Data

Since 1983, the USGS has maintained two continuousrecord stream-gaging stations in the Nā Wai ‘Ehā area: Figure 20. Photograph of subvertical drop near an altitude of 370 feet, ÿÏao Stream, 

Maui, Hawaiÿi (June 6, 2006). 

Figure 20. Photograph of subvertical drop near an altitude 

of 370 feet, ÿÏao Stream, Maui, Hawaiÿi (June 6, 2006).

34 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
station 16614000 (Waihe‘e River above Waihe‘e Ditch intake 

near Waihe‘e, Maui, Hawai‘i) and station 16604500 (‘Īao 

Stream at Kepaniwai Park near Wailuku, Maui, Hawai‘i) (fig. 

7). Data from these two stations can be used to characterize 

the natural, undiverted flows in Waihe‘e River and ‘Īao 

Stream for recent conditions. Complete data are available for 

stations 16614000 and 16604500 during climate years 1984–

2007, and this common period is used for characterizing 

flows in this report. A climate year starts on April 1 and ends 

on March 31 of the following year and is named according to 

the calendar year in which it starts. Climate years maintain 

the integrity of the dry season, which occurs during May 

through September in the study area (fig. 4), and therefore 

are useful for characterizing low-flow characteristics. 

On the basis of long-term data available from 

Honokōhau Stream (station 16620000, fig. 1, northwest of 

Waihe‘e River), mean flow during climate years 1984–2007 

was 24 Mgal/d (37 ft3/s), compared to 25 Mgal/d (39 ft3/s) 

during climate years 1914–2007 (complete data during 

climate years 1920–22 and 1988–90 were not available). 

Thus, data from 1984–2007 appear to provide a reasonable 

proxy for long-term data in the study area. Continuous 

streamflow data for Waiehu and Waikapū Streams during 

climate years 1984–2007 are not available, although flow 

statistics for these streams can be estimated using recordextension methods. 

Waiheÿe River

During climate years 1984–2007, the mean discharge 

measured at gaging station 16614000 was 47.3 Mgal/d (73.2 

ft3/s) and annual mean discharges at station 16614000 ranged 

from 31.8 Mgal/d (49.2 ft3/s) in 1984 to 70.5 Mgal/d (109 

ft3/s) in 1987 (fig. 25). Daily mean discharges in Waihe‘e 

River over the same period are much more variable than 

annual mean discharges, ranging from 14 to 750 Mgal/d (22 to 

1,160 ft3/s). 

During climate years 1984–2007, mean monthly discharge 

in Waihe‘e River (station 16614000) was greatest during 

March and April (54.6 Mgal/d; 84.5 ft3

/s) toward the end of the 

wet season and least during October (42.3 Mgal/d; 65.4 ft3/s) 

at the start of the wet season (fig. 26). The pattern of mean 

monthly streamflow generally is consistent with the pattern of 

mean monthly rainfall measured by rain gages near the wetter, 

mountainous interior parts of the Nā Wai ‘Ehā area (fig. 4).

A flow-duration curve for daily mean discharges is a 

cumulative-frequency curve that shows the percentage of days 

specified discharges were equaled or exceeded during a given 

time period. Although a flow-duration curve does not account 

for the actual sequence of flows being characterized, it does 

provide insight into the availability and variability of flows at 

a site. The median discharge, or Q50, during a specified period 

is the discharge that is equaled or exceeded 50 percent of the 

time. Similarly, the Q95 discharge during a specified period 

is the discharge that is equaled or exceeded 95 percent of the 

time and, therefore, represents a lower discharge than the 

Q50 discharge. The flow-duration curve (based on daily mean 

discharges) for station 16614000 for climate years 1984–2007 

indicates that the median discharge was 34 Mgal/d (52 ft3/s) 

and the Q95 discharge was 22 Mgal/d (34 ft3/s) (fig. 27; table 

13). For climate years 1984–2007 for station 16614000, the 

overall ratio of the Q95 to the Q50 discharges was 0.65. In 

contrast to the mean monthly discharges, which were greatest 

during March and April and least during October, the median 

monthly discharges generally were greatest during July or 

August and least during February (fig. 26). The median 

monthly discharges are less variable than the mean monthly 

discharges, which are more affected by periods of high 

discharge. 

ÿĪao Stream

During climate years 1984–2007, the mean discharge 

measured at gaging station 16604500 was 41.5 Mgal/d (64.2 

ft3/s) and annual mean discharges at station 16604500 ranged 

from 20.8 Mgal/d (32.2 ft3/s) in 1984 to 57.1 Mgal/d (88.3 ft3/s) 

in 1987 (fig. 25). Daily mean discharges in ‘Īao Stream during 

the same period are much more variable than annual mean 

discharges, ranging from 6.1 to 1,100 Mgal/d (9.4 to 1,700 ft3/s). 

During climate years 1984–2007, mean monthly 

discharge in ‘Īao Stream (station 16604500) was greatest 

during March (54.2 Mgal/d; 83.8 ft3/s) toward the end of the 

wet season and least during September (30.2 Mgal/d; 46.7 

ft3/s) toward the end of the dry season (fig. 26). The pattern 

of mean monthly streamflow generally is consistent with 

the pattern of mean monthly rainfall measured by rain gages 

near the wetter, mountainous interior parts of the Nā Wai 

‘Ehā area (fig. 4).

The flow-duration curve for station 16604500 for climate 

years 1984–2007 indicates that the median discharge was 25 

Mgal/d (39 ft3/s) and the Q95 discharge was 11 Mgal/d (17 

ft3/s) (fig. 27; table 13). For climate years 1984–2007 for station 

16604500, the overall ratio of the Q95 to the Q50 discharges 

was 0.44, reflecting more low-flow variability than at station 

16614000 on Waihe‘e River. In contrast to the mean monthly 

discharges, which were greatest during March and least during 

September, the median monthly discharges were greatest during 

April or August and least during October (fig. 26). 

Waiehu and Waikapu- Streams

Complete records of discharge from stream-gaging 

stations on North Waiehu, South Waiehu, and Waikapū 

Streams during climate years 1984–2007 are unavailable 

to define natural-flow characteristics for these streams. 

Continuous-record stream-gaging stations currently are not 

being operated on these streams, although historical daily 

streamflow data for these streams from about 1911 to 1917 

have been published by the U.S. Geological Survey (Martin 

Natural, Undiverted Low-Flow Characteristics 35
and Pierce, 1913; Pierce and Larrison, 1914; Larrison, 1915; 

Grover and Larrison, 1917a,b, 1918; Wells, 1961). These 

historical records can be extended to provide estimates of 

natural-flow characteristics that reflect recent conditions 

(1984–2007 climate years). The recent base period covering 

the 1984–2007 climate years is used for the record extension 

of historical data from North Waiehu, South Waiehu, and 

Waikapū Streams. On the basis of available data from 

Honokōhau Stream (station 16620000), mean flow during the 

1984–2007 base period was 24 Mgal/d (37 ft3

/s), compared 

to 36 Mgal/d (55 ft3

/s) during climate years 1914–17. Thus, 

historical data from Waiehu and Waikapū Streams may reflect 

a wetter period relative to the 1984–2007 base period. 

Daily streamflow data for North Waiehu, South Waiehu, 

and Waikapū Streams are available during the period from 

about 1911 to 1917, although the records have numerous data 

gaps (fig. 28). In some cases, discharge data from streamgaging stations upstream of diversions can be used to estimate 

natural flow characteristics. In other cases, discharge data 

from a stream-gaging station (downstream of diversions) and 

ditch-gaging stations can be combined to estimate natural-flow 

characteristics for the stream.

Daily discharge data from additional gaging stations 

(index stations) are needed to extend the records of North 

Waiehu, South Waiehu, and Waikapū Streams. For each index 

station, at least two years of concurrent (relative to the records 

of North Waiehu, South Waiehu, and Waikapū Streams) 

historical data were considered the minimum to include the 

index station in the analysis. Data from index stations on 

Waihe‘e River and ‘Īao, Honokōhau, and Honopou Streams 

can be correlated with concurrent data from North Waiehu, 

South Waiehu, and Waikapū Streams for record extension. 

Because of limitations described below, data from all four 

index stations were used to provide a range of estimated 

natural-flow characteristics for the recent base period 1984–

2007. All index stations had complete (or nearly complete in 

the case of Honokōhau Stream) data during the 1984–2007 

base period.

North Waiehu Stream.—Historical data that can 

be used to estimate natural-flow characteristics of North 

36 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄

Table 11. Selected active and historical U.S. Geological Survey (USGS) gaging stations in and near the Na− Wai ÿEha−, Maui, Hawaiÿi.

[SW, continuous-record stream-gaging station; CSG, crest-stage gage; p, present (2009); station names are as they appear in the USGS National Water Information System database]

USGS site 

number Station name Altitude,in feet

Period of

record

Station 

type Comment

16587000 Honopou Stream near Huelo, Maui, HI 1,208 1910–p SW1 outside of study area

16604000 IAO STREAM NR WAILUKU, MAUI, HI 860 1910–15 SW1 natural, undiverted flow

16604500 Iao Stream at Kepaniwai Park nr Wailuku, Maui, HI 780 1983–p SW1 natural, undiverted flow

16605000 MANIANIA DITCH NR WAILUKU,MAUI,HI 740 1910–13 Ditch ditch flow

16607000 Iao Stream at Wailuku, Maui, HI 250 1950–51;1950–p SW; CSG2 downstream of diversions

16608000 NORTH WAIEHU STREAM NR WAILUKU, MAUI, HI 880 1912–15 SW natural, undiverted flow

16609000 N WAIEHU DITCH NR WAILUKU,MAUI,HI 840 1910–11;1916–17 Ditch ditch flow

16609500 N WAIEHU STR BL N WAIEHU DITCH NR WAILUKU, MAUI 730 1910–11 SW downstream of diversion

16610000 SOUTH WAIEHU STREAM NR WAILUKU, MAUI, HI 870 1910–17 SW natural, undiverted flow

16611000 S WAIEHU DITCH NR WAILUKU,MAUI,HI 860 1912–13 Ditch ditch flow

16612000 WAIHEE RIVER NR WAIHEE, MAUI, HI 620 1913–17 SW1 natural, undiverted flow

16613000 WAIHEE CANAL NR WAIHEE,MAUI,HI 600 1910–12 Ditch ditch flow

16613500 WAIHEE CANAL AT WAIALE WEIR NR WAILUKU,MAUI,HI 450 1911–12 Ditch ditch flow

16614000 Waihee Rv abv Waihee Dtch intk nr Waihee, Maui, HI 605 1983–p SW1 natural, undiverted flow

16615000 SPRECKELS DITCH NR WAIHEE, MAUI, HI 380 1910–13 Ditch ditch flow

16616000 SPRECKLES DITCH AT WAIALE WEIR NR WAILUKU,MAUI 230 1910–11 Ditch ditch flow

16620000 Honokohau Stream near Honokohau, Maui, HI 870 1911–p3 SW1 outside of study area

16648000 SOUTH SIDE WAIKAPU DITCH NR WAIKAPU, MAUI, HI 1,100 1910–17 Ditch4 ditch flow

16649000 PALOLO DITCH NR WAIKAPU, MAUI, HI 880 1910–17 Ditch4 ditch flow

16650000 WAIKAPU STREAM NR WAIKAPU,MAUI,HI 880 1910–17 SW4 downstream of diversions

16650200 Waikapu Stream at Waikapu, Maui, HI 340 2002–p CSG downstream of diversions

16650500 Waikapu Stream at Waikapu, Maui, HI 340 1963–97 CSG downstream of diversions

1

Station used as an index station for record extension purposes.

2

SW station 1950–51; CSG station 1950–present.

3

No data available during calendar years 1912, 1921, and 1989.

4

Data from stations 16648000, 16649000, and 16650000 combined to estimate discharge in Waikapü Stream near an altitude of 880 feet.
16615000

205651156303901205648156304301205644156304401

205633156322401

205627156323401

205625156323401

205621156323601

205618156323901

20561015632470220561015632470116612000

205640156305201205639156305401205639156305801

205633156315801205634156320601205634156321101205634156321801205633156321901205632156322001

205634156315001205634156314701205634156314201205635156313901205634156313801

205615156324201205615156324301205613156324401

205613156323901205613156323902 205611156324601

16614000

Fig. 6A

Fig. A5 Fig. 45B

Fig. 2 Figs. A3, A4

Fig. A2

16613000

0 1,000 2,000 3,000 4,000 FEET

0 0.25 0.5 0.75 1 KILOMETERS

Base modified from U.S. Geological Survey Digital RasterGraphics topographic map, 1:24,000 scale, Universal Transverse Mercator projection, zone 4, NAD83 datum.

DISCHARGE-MEASUREMENT SITE AND NUMBERTEMPERATURE-MEASUREMENT SITE AND NUMBERHABITAT-MEASUREMENT SITEMOUNTED-CAMERA SITEPHOTOGRAPHED SITE AND FIGURE NUMBER

EXPLANATION

205639156305801205611156324601

Fig. 2

156°31' 156°32' 156°33'

20°57'20°56'

Figure 21. Discharge-, temperature-, and habitat-measurement sites, mounted-camera sites, and photographed sites, Waiheÿe River, Maui, Hawaiÿi. Figure 21. Discharge-, temperature-, and habitat-measurement sites, mounted-camera sites, and photographed sites, Waiheÿe River, Maui, Hawaiÿi.

Natural, Undiverted Low-Flow Characteristics 37
16611000

1660900016609500

205455156302301

205448156302801

205439156303401

205432156310401205433156310101205435156305801205450156303601

20543415631570120543415631550116608000205435156315201205435156315001

205432156312801205432156312701205437156312301

205433156311501205423156311501205420156311301205420156311302

205420156305401

205415156310001

205506156293501205506156294501205504156295101

205451156303501205452156303401205451156303401205450156303201205449156302801

205451156302401

205435156315101205435156314701

205426156313601205427156313101

205422156305401205421156310301

Fig. 6B

Fig. 16

Figs. A8, 17

Fig. A7A

Cover

Fig. A7B Fig. 44B

Fig. A6

0 1,000 2,000 3,000 4,000 FEET

0 0.25 0.5 0.75 1 KILOMETERS

Base modified from U.S. Geological Survey Digital RasterGraphics topographic map, 1:24,000 scale, Universal Transverse Mercator projection, zone 4, NAD83 datum.

DISCHARGE-MEASUREMENT SITE AND NUMBERTEMPERATURE-MEASUREMENT SITE AND NUMBERHABITAT-MEASUREMENT SITEMOUNTED-CAMERA SITEPHOTOGRAPHED SITE AND FIGURE NUMBER

EXPLANATION

Fig. 16

205434156315701205433156311501

156°30' 156°31' 156°32'

20°55'20°54'

Figure 22. Discharge-, temperature-, and habitat-measurement sites, mounted-camera sites, and photographed sites, Waiehu Stream, Maui, Hawaiÿi. Figure 22. Discharge-, temperature-, and habitat-measurement sites, mounted-camera sites, and photographed sites, Waiehu Stream, Maui, Hawaiÿi.

38 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Figure 23. Discharge-, temperature-, and habitat-measurement sites, mounted-camera sites, and photographed sites, ÿÏao Stream, Maui, Hawaiÿi.

16613500

16607000

16604500

205333156300901

205315156304001

205312156304701205302156305601

205308156304401

205301156315901205300156320001205300156320002

16604000, 16605000

205300156321401

205258156320201

205303156315201205303156315101205303156314701205304156314401205303156314001205303156314002

205301156310501

205300156305501

205257156321002205257156321001205257156321101

205250156324401205255156322401205254156322301205257156322001205257156321901205256156321801205256156321701205256156321601

205256156321301205256156321302205256156321303

205425156291701205423156292101

Fig. 3

Fig. 19 Fig. ES3

Fig. 6C

Fig. 44A

Figs. 18, 45A

Fig. A11

Fig. A9

Fig. 20

Figs. A10, 46

0 1,000 2,000 3,000 4,000 FEET

0 0.25 0.5 0.75 1 KILOMETERS

Base modified from U.S. Geological Survey Digital RasterGraphics topographic map, 1:24,000 scale, Universal Transverse Mercator projection, zone 4, NAD83 datum.

DISCHARGE-MEASUREMENT SITE AND NUMBERTEMPERATURE-MEASUREMENT SITE AND NUMBERHABITAT-MEASUREMENT SITEMOUNTED-CAMERA SITEPHOTOGRAPHED SITE AND FIGURE NUMBER

EXPLANATION

Fig. 3

205303156314701205250156324401

156°30' 156°31' 156°32'

20°54'20°53'

Figure 23. Discharge-, temperature-, and habitat-measurement sites, mounted-camera sites, and photographed sites, ÿÏao Stream, Maui, Hawaiÿi.

Natural, Undiverted Low-Flow Characteristics 39
16650500

16650200

16648000

205125156304801205124156304401205123156304201205121156304001205118156302901205116156302601205114156302301205112156301601205112156301201 205040156292801

205024156292301

204827156283601

2051221563147012051241563143011664900016650000

205121156320901205122156320601205123156320501205124156320301205125156320101205126156315501

205122156320101205122156320901205121156321501

205120156312801

204850156284901

Fig. A12

Fig. A13

Fig. A14

Fig. A15

Fig. ES2, A16

0 1,000 2,000 3,000 4,000 5,000 FEET

0 0.5 1 1.5 KILOMETERS

Base modified from U.S. Geological Survey Digital RasterGraphics topographic map, 1:24,000 scale, Universal Transverse Mercator projection, zone 4, NAD83 datum.

DISCHARGE-MEASUREMENT SITE AND NUMBERTEMPERATURE-MEASUREMENT SITE AND NUMBERHABITAT-MEASUREMENT SITEMOUNTED-CAMERA SITEPHOTOGRAPHED SITE AND FIGURE NUMBER

EXPLANATION

Fig. A12

205112156301201205121156321501

156°28' 156°29' 156°30' 156°31' 156°32'

20°51'20°50'20°49'20°48'

Figure 24. Discharge-, temperature-, and habitat-measurement sites, mounted-camera sites, and photographed sites, Waikapü Stream, Maui, Hawaiÿi. Figure 24. Discharge-, temperature-, and habitat-measurement sites, mounted-camera sites, and photographed sites, Waikapü Stream, Maui, Hawaiÿi.

40 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Mean

Q50 (median)

Q70 (flow equaled or exceeded 70 percent of the time)

Q90 (flow equaled or exceeded 90 percent of the time)

Q95 (flow equaled or exceeded 95 percent of the time)

ANNUAL FLOW STATISTIC

1985 1995

CLIMATE YEAR

1990 2000 2005

0

20

40

60

80

10

20

30

50

60

70

40

100

120

DISCHARGE, IN CUBIC FEET PER SECOND

DISCHARGE, IN MILLION GALLONS PER DAY

10

0

0

20

30

50

60

70

40

0

20

40

60

DISCHARGE, IN CUBIC FEET PER SECOND

DISCHARGE, IN MILLION GALLONS PER DAY

80

100

120

A

B

Figure 25. Annual flow statistics (climate years 1984–2007) for Waiheÿe River and ÿĪao Stream, Maui, Hawaiÿi. A, 

Waiheÿe River, gaging station 16614000. B, ÿĪao Stream, gaging station 16604500.

Natural, Undiverted Low-Flow Characteristics 41
Figure 26. Monthly flow statistics (climate years 1984–2007) for Waiheÿe River and ÿĪao Stream, Maui, Hawaiÿi. A, 

Waiheÿe River, gaging station 16614000. B, ÿĪao Stream, gaging station 16604500.

Mean

Q50 (median)

Q70 (flow equaled or exceeded 70 percent of the time)

Q90 (flow equaled or exceeded 90 percent of the time)

Q95 (flow equaled or exceeded 95 percent of the time)

MONTHLY FLOW STATISTIC

JAN FEB MAR APR MAY JUNE JULY AUG SEPT OCT NOV DEC

MONTH

DISCHARGE, IN CUBIC FEET PER SECOND

DISCHARGE, IN MILLION GALLONS PER DAY

DISCHARGE, IN CUBIC FEET PER SECOND

DISCHARGE, IN MILLION GALLONS PER DAY

0

20

40

60

80

10

0

20

30

50

60

70

40

100

120

10

0

20

30

50

60

70

40

0

20

40

60

80

100

120

A

B

42 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
07/1913–06/1917 (station 16612000; stations 16613000 and 16614000 combined)

06/1910–05/1915 (station 16604000)

mean discharge (16614000)

mean discharge (16612000, 16613000, 16614000)

mean discharge (16604500)

mean discharge (16604000)

04/1984–03/2008 (station 16604500)

04/1984–03/2008 (station 16614000)

DAILY MEAN DISCHARGE, IN CUBIC FEET PER SECOND

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

PERCENTAGE OF TIME INDICATED DISCHARGE WAS EQUALED OR EXCEEDED

DAILY MEAN DISCHARGE, IN CUBIC FEET PER SECOND

DAILY MEAN DISCHARGE, IN MILLION GALLONS PER DAY DAILY MEAN DISCHARGE, IN MILLION GALLONS PER DAY

10

5

100

1,000

5,000

10

5

100

1,000

10

100

1,000

10

100

1,000

5,000

A

B

Figure 27. Flow-duration curves for early historical period and climate years 1984–2007, Waiheÿe River and ÿĪao Stream, 

Maui, Hawaiÿi. A, Waiheÿe River, gaging stations 16612000, 16613000, and 16614000. B, ÿĪao Stream, gaging stations 

16604000 and 16604500.

Natural, Undiverted Low-Flow Characteristics 43
1910 1911 1912 1913 1914 1915 1916 1917

North Waiehu Stream

South Waiehu Stream

Waikapü Stream

Waiheÿe River

Honoköhau Stream 16620000

16587000

16604000

16613000 and 16614000

16648000, 16649000, and 16650000

16610000

16609000 and 16609500 16608000

16612000

Honopou Stream

ÿÏao Stream

Figure 28. Time lines of available data from selected gaging stations (numbers on lines) during 1910–17, Maui, Hawaiÿi.

Figure 28. Time lines of available data from selected gaging stations (numbers on lines) during 1910–17, Maui, Hawaiÿi.

44 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄

Table 13. Selected duration discharges (natural, undiverted conditions) for Waiheÿe River and 

ÿI

−

ao, Honoko−hau, and Honopou Streams during climate years 1984–2007, Maui, Hawaiÿi.

[Mgal/d, million gallons per day]

Flow-duration 

percentile

Duration discharge for indicated stream and gaging station, in Mgal/d

(values in parentheses are in cubic feet per second)

Waiheÿe River 

(16614000)

ÿI

−

ao Stream 

(16604500)

Honopou Stream 

(16587000)

Honoko

−hau Stream 

(16620000)1

50 34 (52) 25 (39) 1.4 (2.1) 14 (22)

55 32 (50) 23 (35) 1.2 (1.9) 14 (21)

60 31 (48) 21 (32) 1.0 (1.6) 12 (19)

65 30 (46) 19 (30) 0.90 (1.4) 12 (18)

70 28 (44) 17 (27) 0.84 (1.3) 11 (17)

75 28 (43) 16 (25) 0.71 (1.1) 10 (16)

80 27 (41) 15 (23) 0.58 (0.90) 9.7 (15)

85 25 (39) 14 (21) 0.49 (0.76) 9.0 (14)

90 24 (37) 12 (19) 0.39 (0.61) 8.4 (13)

95 22 (34) 11 (17) 0.32 (0.49) 7.8 (12)

99 18 (28) 8.4 (13) 0.17 (0.26) 6.3 (9.8)

1

Climate years 1984–87, 1991–2007.
Waiehu Stream are available from gaging stations 16608000, 

16609000, and 16609500. Gaging station 16608000 measured 

the natural flow in North Waiehu Stream at an altitude of about 

880 ft, upstream of all diversions. Gaging station 16609000 

measured the flow in North Waiehu Ditch, which diverted 

water from North Waiehu Stream about 50 ft downstream 

of gaging station 16608000 (Wells, 1961). Gaging station 

16609500 measured the flow remaining in North Waiehu 

Stream at an altitude of about 730 ft, downstream of the North 

Waiehu Ditch diversion. Combining the concurrent flows 

measured at gaging stations 16609000 and 16609500 provides 

an estimate of the natural flow in the stream near an altitude of 

730 ft. However, because of unquantified losses in the reach 

between altitudes of 880 and 730 ft, the combined flows from 

stations 16609000 and 16609500 were not used in the analysis. 

During the period of record for gaging station 16608000 

(1912–15), the minimum reported flow based on stage readings 

made twice daily (Grover and Larrison, 1917a) was 1.6 Mgal/d 

(2.5 ft3/s) during March 1915. 

South Waiehu Stream.— Historical data that can be 

used to estimate natural-flow characteristics of South Waiehu 

Stream are available from gaging station 16610000. Gaging 

station 16610000 measured the flow in South Waiehu Stream 

at an altitude of about 870 ft, upstream of most diversions. 

A small taro ditch diverted about 0.06–0.2 Mgal/d (0.1–0.3 

ft3/s) at typical stages upstream of station 16610000 (Larrison, 

1915; Grover and Larrison, 1917a,b, 1918; Wells, 1961). For 

the purposes of this study, data from gaging station 16610000 

are assumed to be representative of natural-flow conditions in 

South Waiehu Stream. During the period of record for gaging 

station 16610000 (1910–11, 1913–17), the minimum reported 

flow based on stage readings made twice daily (Grover and 

Larrison, 1917a) was 1.5 Mgal/d (2.3 ft3/s) during July 1913.

Waikapü Stream.— Historical data that can be used to 

estimate natural-flow characteristics of Waikapū Stream are 

available from gaging stations 16648000, 16649000, and 

16650000 during 1910–17. Two water-development tunnels 

driven in 1905 and 1906 at altitudes of about 1,800 and 1,770 

ft, respectively, may have contributed to measured flow in 

Waikapū Stream, although the tunnel at an altitude of 1,770 ft 

produced only about 0.007 Mgal/d (0.01 ft3/s) (table 2). Gaging 

station 16648000 measured the flow in the South Side Ditch, 

which diverted water from Waikapū Stream at an altitude of 

about 1,120 ft. Gaging station 16649000 measured the flow in 

the Everett Ditch (also referred to as the Palolo Ditch), which 

diverted water from Waikapū Stream at an altitude of about 

900 ft. Gaging station 16650000 measured the flow remaining 

in Waikapū Stream at an altitude of about 880 ft, downstream 

of the South Side Ditch and Everett Ditch diversions (Wells, 

1961). Combining the concurrent flows measured at gaging 

stations 16648000, 16649000, and 16650000 provides an 

estimate of the natural flow in Waikapū stream near an 

altitude of 880 ft. This estimate assumes no losses or return 

flows between the South Side Ditch diversion and station 

16650000 during the period when the gaging stations were 

operated. Recent U.S. Geological Survey seepage-run data 

(see section below on “Seepage-Run Measurements”) support 

the assumption of relatively small loss between the South Side 

Ditch diversion and station 16650000. During the period of 

record of gaging stations 16648000, 16649000, and 16650000 

(1910–17), the minimum estimated combined discharge at 

these stations, based on stage readings made twice daily, was 

3.3 Mgal/d (5.1 ft3

/s) during October 1912.

Waihe‘e River.— Historical data from Waihe‘e River that 

can be correlated with data from North Waiehu, South Waiehu, 

and Waikapū Streams are available from gaging stations 

16612000, 16613000, and 16614000. Two water-development 

tunnels driven in 1909 at altitudes of about 1,625 and 1,650 

ft may have contributed to measured flow in Waihe‘e River, 

although flow in the river may not have been appreciably 

increased after the initial storage of groundwater developed by 

the tunnels had been depleted (Stearns and Macdonald, 1942, 

p. 195–196). Gaging station 16612000 measured the flow in 

Waihe‘e River at an altitude of about 620 ft, upstream of all 

diversions. Gaging station 16613000 measured the flow in the 

Waihe‘e Ditch, which diverted water from Waihe‘e River at an 

altitude of about 600 ft. Before 1913, gaging station 16614000 

measured the flow remaining in Waihe‘e River, downstream 

of the Waihe‘e Ditch diversion. Combining the historical 

concurrent flows measured at gaging stations 16613000 and 

16614000 provides an estimate of the flow in Waihe‘e River at 

an altitude of about 605 ft, upstream of all diversions. Gaging 

station 16614000 was reestablished in 1983, after which it 

measured the flow in Waihe‘e River at an altitude of about 

605 ft, upstream of all diversions. Stations 16612000 and 

16614000 (at its current location) are within a few hundred 

feet of each other, and therefore data from these two stations 

are assumed to represent equivalent conditions.

‘Ïao Stream.—Historical data from ‘Īao Stream that can 

be correlated with data from North Waiehu, South Waiehu, and 

Waikapū Streams are available from gaging station 16604000. 

Gaging station 16604000 measured the flow in ‘Īao Stream 

at an altitude of about 860 ft, upstream of all diversions. Two 

water-development tunnels were driven in 1906 near altitudes 

of 1,425 and 1,475 ft, upstream of gaging station 16604000, 

and may have affected measured flow at the gaging station, 

although no information is available to quantify the effects. 

For the purposes of this study, flow measured at gaging station 

16604000 is assumed to represent the natural flow in ‘Īao 

Stream at an altitude of about 860 ft. Active (2009) gaging 

station 16604500 was established in 1983 at an altitude of 

about 780 ft, upstream of all diversions. In addition to the 

two water-development tunnels mentioned above, another 

water-development tunnel at an altitude of about 787 ft may 

affect flow measured at gaging station 16604500, although no 

information is available to quantify the effects. The tunnel at 

an altitude of about 787 ft caused another nearby tunnel at an 

altitude of 1,305 ft to cease flowing (Yamanaga and Huxel, 

1970). For the purposes of this study, flow measured at gaging 

station 16604500 is assumed to represent natural flow in 

Natural, Undiverted Low-Flow Characteristics 45
‘Īao Stream at an altitude of about 780 ft. Data from gaging 

stations 16604000 and 16604500 are assumed to represent 

equivalent conditions, although station 16604500 is about 

1,000 ft downstream of where station 16604000 was located. 

Data are unavailable to determine whether ‘Īao Stream gains 

or loses water in this 1,000-ft reach, although the reach is 

within an area of mapped dikes and high groundwater levels 

and therefore likely gains water. Because of uncertainty in the 

equivalence of flow conditions at gaging stations 16604000 

and 16604500, use of these index stations is considered least 

reliable. 

Honoköhau Stream.—Historical data from Honokōhau 

Stream that can be correlated with data from North Waiehu, 

South Waiehu, and Waikapū Streams are available from gaging 

station 16620000. Gaging station 16620000 is an active (2009) 

station that measures the natural flow in Honokōhau Stream at 

an altitude of about 870 ft, upstream of all diversions.

Honopou Stream.—Historical data from Honopou Stream 

that can be correlated with data from North Waiehu, South 

Waiehu, and Waikapū Streams are available from gaging station 

16587000. Gaging station 16587000 is an active (2009) station 

that measures the natural flow in Honopou Stream at an altitude 

of about 1,210 ft, upstream of all diversions.

Record-Extension Method

The record-extension method used for this study is 

described by Ries (1993) and is summarized in the steps 

below.

1. Selected duration discharges between the median 

(Q50) and Q99 discharges were computed for the period 

formed by years with complete and nearly complete 

record for each short-term, historical gaged site. The 

Q50 discharge represents the discharge that is equaled 

or exceeded 50 percent of the time, and the Q99

discharge represents the discharge that is equaled or 

exceeded 99 percent of the time. The selected duration 

discharges (Q50, Q55, Q60, Q65, Q70, Q75, Q80, Q85, Q90, 

Q93, Q95, Q97, Q98, and Q99) represent discharges from 

the lower half of a flow-duration curve (Searcy, 1959). 

Because limited data were available for analysis, 

years with as many as 48 days of missing record were 

included (table 14). 

2. The selected duration discharges listed above were 

computed for concurrent periods (relative to the periods 

for each short-term, historical gaged site) for each of 

the index stations.

3. Correlation coefficients between the base-10 logarithms 

of the duration discharges for the concurrent period at 

a short-term site and each index site were computed. 

For this study, all correlation coefficients between data 

from short-term and index sites exceeded 0.8. All index 

stations were therefore retained for analysis.

4. Concurrent duration discharges for each pairing of 

short-term gaged site and index station were plotted in 

log-space to test for curvature in the relation between 

the two sites.

The graphical-correlation method (Searcy, 1959) was used 

to estimate selected duration discharges at the short-term site for 

the base period. The graphical-correlation method, instead of 

the MOVE.1 method (Hirsch, 1982), was necessitated because 

some measure of curvature was detected in all relations from 

step 4. The graphical-correlation method involves (1) drawing 

a smooth curve through the plotted points of the concurrent 

duration discharges at the short-term site and index station, 

(2) estimating selected duration discharges for the base period 

(1984–2007) at the index station, (3) estimating the selected 

duration discharges at the short-term site during the base period 

from the smooth curve by reading the discharge (at the shortterm site) corresponding to the base period duration discharges 

at the index station. For the purposes of estimating the selected 

duration discharges at the short-term site during the base period, 

data were replotted on an arithmetic scale (figs. 29–31) to 

reduce extreme low-end curvature and simplify extrapolations 

to low flows.

Estimated Streamflow During 1984–2007

For this study, selected duration discharges from the Q50

to the Q99 discharges were estimated for the base period for 

sites on North Waiehu, South Waiehu, and Waikapū Streams. 

These estimated flow characteristics generally are representative 

of natural-flow conditions during the 1984–2007 base period. 

Different estimates for the 1984–2007 base-period duration 

discharges are available, depending on the index station 

used. Because of the limited data available for analysis and 

uncertainty associated with the estimated duration discharges 

for the sites on North Waiehu, South Waiehu, and Waikapū 

Streams, values based on each of the four index stations for the 

1984–2007 base period are presented (tables 15–17). In general, 

the largest estimated duration discharges during the base period 

are associated with the index station on ‘Īao Stream, and the 

smallest estimated duration discharges are associated with the 

index station on Honokōhau Stream (tables 15–17). Estimated 

duration discharges using the index stations on ‘Īao Stream 

are considered least reliable because of possible streamflow 

gain between historical station 16604000 and active station 

16604500 and were not used to compute average estimates 

(tables 15–17). Estimated duration discharges below the Q90

discharge (that is, Q93, Q95, Q97, Q98, and Q99) are considered 

least reliable, because extrapolation of curves was necessary to 

make estimates in some cases.

Index Stations.—Complete data from gaging stations 

16614000 on Waihe‘e River, 16604500 on ‘Īao Stream, 

and 16587000 on Honopou Stream are available during 

the 1984–2007 base period (table 13). For gaging station 

16614000 on Waihe‘e River, the Q99 and Q50 duration 

46 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
discharges during 1984–2007 were 18 and 34 Mgal/d (28 and 

52 ft3/s), respectively. For gaging station 16604500 on ‘Īao 

Stream, the Q99 and Q50 duration discharges during 1984–2007 

were 8.4 and 25 Mgal/d (13 and 39 ft3/s), respectively. For 

gaging station 16587000 on Honopou Stream, the Q99 and 

Q50 duration discharges during 1984–2007 were 0.17 and 1.4 

Mgal/d (0.26 and 2.1 ft3/s), respectively. For gaging station 

16620000 on Honokōhau Stream, the Q99 to Q50 duration 

discharges were computed for the period 1984–87 and 1991–

2007 (complete data during climate years 1988–90 were not 

available) and ranged from 6.3 to 14 Mgal/d (9.8 to 22 ft3/s) 

(table 13). Duration discharges for Waihe‘e River and ‘Īao 

Stream were computed for the 1984–2007 base period both 

with and without data from climate years 1988–90, and the 

resulting duration discharges (less than or equal to the Q50) 

for the incomplete period generally were less than, but within 

5 percent of, the corresponding duration discharges for the 

complete period. Thus, incomplete data from Honokōhau 

Stream during 1984–2007 are considered representative of the 

entire base period. The base-period duration discharges from 

the index stations were used in conjunction with the curves of 

concurrent duration discharges (figs. 29–31) to estimate the 

base-period duration discharges near gaging stations 16608000 

(North Waiehu Stream), 16610000 (South Waiehu Stream), 

and 16650000 (Waikapū Stream) (tables 15–17). 

North Waiehu Stream.—For North Waiehu Stream 

near gaging station 16608000, the estimated median (Q50) 

discharges during 1984–2007, using the index stations from 

Waihe‘e River, Honokōhau Stream, and Honopou Stream only, 

ranged from 2.8 to 3.5 Mgal/d (4.4 to 5.4 ft3/s) and averaged 

3.2 Mgal/d (4.9 ft3

/s) (table 15). The estimated Q70 discharges 

during 1984–2007 ranged from 2.1 to 2.7 Mgal/d (3.2 to 4.2 

ft3/s), and the estimated Q90 discharges ranged from 1.2 to 2.2 

Mgal/d (1.8 to 3.4 ft3/s) (table 15).

South Waiehu Stream.— For South Waiehu Stream 

near gaging station 16610000, the estimated median (Q50) 

discharges during 1984–2007, using the index stations from 

Waihe‘e River, Honokōhau Stream, and Honopou Stream only, 

ranged from 2.4 to 4.0 Mgal/d (3.7 to 6.2 ft3/s) and averaged 

3.2 Mgal/d (5.0 ft3/s) (table 16). The estimated Q70 discharges 

during 1984–2007 ranged from 1.8 to 2.8 Mgal/d (2.8 to 4.3 

ft3/s), and the estimated Q90 discharges ranged from 1.2 to 1.6 

Mgal/d (1.9 to 2.4 ft3

/s) (table 16).

Waikapü Stream.— For Waikapū Stream near gaging 

station 16650000, the estimated median (Q50) discharges 

during 1984–2007, using the index stations from Waihe‘e 

River, Honokōhau Stream, and Honopou Stream only, ranged 

from 4.8 to 6.1 Mgal/d (7.5 to 9.5 ft3/s) and averaged 5.6 

Mgal/d (8.6 ft3/s) (table 17). The estimated Q70 discharges 

during 1984–2007 ranged from 3.7 to 5.0 Mgal/d (5.8 to 7.8 

ft3/s), and the estimated Q90 discharges ranged from 3.1 to 4.1 

Mgal/d (4.8 to 6.3 ft3/s) (table 17).

Limitations

The estimates of duration discharges for the base period 

for North Waiehu, South Waiehu, and Waikapū Streams are 

uncertain because of several data limitations. These limitations 

are described below. 

Natural, Undiverted Low-Flow Characteristics 47

Table 14. Concurrent periods used for extension of records from North Waiehu, South Waiehu, and Waikapu− Streams, West 

Maui, Hawaiÿi.

[values in parentheses indicate number of missing days in the year]

Stream and index 

station(s)

Periods of historical data available for record extension for indicated gaging stations

North Waiehu Stream

station 16608000

South Waiehu Stream

station 16610000

Waikapu

− Stream

stations 16648000, 16649000, 16650000

Waiheÿe River,

stations 16612000, 

16613000, 

16614000

04/1913 to 03/1914

04/1914 to 03/1915

01/1911 to 12/1911

04/1913 to 03/1914

04/1914 to 03/1915 (26)

04/1916 to 03/1917 (24)

01/1911 to 12/1911

01/1914 to 12/1914

05/1916 to 04/1917 (9)

ÿÏao Stream, 

station 16604000

07/1912 to 06/1913 (48)

07/1913 to 06/1914 (21)

01/1911 to 12/1911

06/1913 to 05/1914

01/1911 to 12/1911

01/1912 to 12/1912

07/1913 to 06/1914 (21)

Honoköhau Stream, 

station 16620000

06/1913 to 05/1914

06/1914 to 05/1915

06/1913 to 05/1914

01/1915 to 12/1915

04/1916 to 03/1917 (24)

07/1913 to 06/1914

07/1914 to 06/1915 (5)

07/1916 to 06/1917 (9)

Honopou Stream, 

station 16587000

07/1912 to 06/1913 (8)

07/1913 to 06/1914 

07/1914 to 06/1915

01/1911 to 12/1911

04/1913 to 03/1914

01/1915 to 12/1915

04/1916 to 03/1917 (24)

01/1911 to 12/1911

01/1912 to 12/1912

07/1913 to 06/1914

07/1914 to 06/1915 (5)

05/1916 to 04/1917 (9)
Q50

Q70

Q90

Q50

Q70

Q90

Q50

Q70

Q90

Q50

Q70

Q90

DISCHARGE, IN CUBIC FEET PER SECOND,

NORTH WAIEHU STREAM AT GAGING STATION 16608000

DISCHARGE, IN CUBIC FEET PER SECOND,

NORTH WAIEHU STREAM AT GAGING STATION 16608000

DISCHARGE, IN CUBIC FEET PER SECOND,

ÿÏAO STREAM AT GAGING STATION 16604500

0 1 2 3

DISCHARGE, IN CUBIC FEET PER SECOND,

HONOPOU STREAM AT GAGING STATION 16587000

4

0 20 40 60

DISCHARGE, IN CUBIC FEET PER SECOND,

WAIHEÿE RIVER AT GAGING STATION 16614000

80

0 10 20

DISCHARGE, IN CUBIC FEET PER SECOND,

HONOKÖHAU STREAM AT GAGING STATION 16620000

30 40

0 10 20 30 40 0

1

2

3

4

5

6

7

8

0

1

2

3

4

5

6

7

8

0

1

2

3

4

5

6

7

8

0

1

2

3

4

5

6

A

C D

B

LEADER LINE FOR 1984–2007 

 DURATION DISCHARGES

GRAPHICAL FIT TO HISTORICAL

 DURATION DISCHARGES

HISTORICAL (1912–15) 

 DURATION DISCHARGES

Figure 29. Relation between concurrent duration discharges for North Waiehu Stream and index stations during 

the period 1912–15, and selected duration discharges for North Waiehu Stream and index stations during the 

1984–2007 base period, Maui, Hawaiÿi. A, Index station 16614000, Waiheÿe River. B, Index station 16604500, ÿĪao 

Stream. C, Index station 16620000, Honoköhau Stream. D, Index station 16587000, Honopou Stream.

48 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Q50

Q70

Q90

Q50

Q70

Q90

Q50

Q70

Q90

Q50

Q70

Q90

0

1

2

3

4

5

6

7

8

0 1 2 3 4 5 0

1

2

3

4

5

6

7

8

DISCHARGE, IN CUBIC FEET PER SECOND,

SOUTH WAIEHU STREAM AT GAGING STATION 16610000

DISCHARGE, IN CUBIC FEET PER SECOND,

SOUTH WAIEHU STREAM AT GAGING STATION 16610000

DISCHARGE, IN CUBIC FEET PER SECOND,

HONOPOU STREAM AT GAGING STATION 16587000

0 20 40 60 80 100 0 10 20 30 40 50 60 0

1

2

3

4

5

6

7

8

0

1

2

3

4

5

6

7

8

DISCHARGE, IN CUBIC FEET PER SECOND,

WAIHEÿE RIVER AT GAGING STATION 16614000

DISCHARGE, IN CUBIC FEET PER SECOND,

HONOKÖHAU STREAM AT GAGING STATION 16620000

0 10 20 30 40

DISCHARGE, IN CUBIC FEET PER SECOND,

ÿÏAO STREAM AT GAGING STATION 16604500

A

C D

B

LEADER LINE FOR 1984–2007 

 DURATION DISCHARGES

GRAPHICAL FIT TO HISTORICAL

 DURATION DISCHARGES

HISTORICAL (1911–17) 

 DURATION DISCHARGES

Figure 30. Relation between concurrent duration discharges for South Waiehu Stream and index stations during 

the period 1911–17, and selected duration discharges for South Waiehu Stream and index stations during the 

1984–2007 base period, Maui, Hawaiÿi. A, Index station 16614000, Waiheÿe River. B, Index station 16604500, ÿĪao 

Stream. C, Index station 16620000, Honoköhau Stream. D, Index station 16587000, Honopou Stream.

Natural, Undiverted Low-Flow Characteristics 49
Q50

Q70

Q90

Q50

Q70

Q90

Q50

Q70

Q90

Q50

Q70

Q90

DISCHARGE, IN CUBIC FEET PER SECOND,

WAIKAPÜ STREAM AT GAGING STATION 16650000

DISCHARGE, IN CUBIC FEET PER SECOND,

WAIKAPÜ STREAM AT GAGING STATION 16650000

0 10 20 30

DISCHARGE, IN CUBIC FEET PER SECOND,

ÿÏAO STREAM AT GAGING STATION 16604500

40 50 0

5

10

15

0 20 40 60

DISCHARGE, IN CUBIC FEET PER SECOND,

WAIHEÿE RIVER AT GAGING STATION 16614000

80 100 120 0

2

4

6

8

10

12

14

16

18

20

0 10 20

DISCHARGE, IN CUBIC FEET PER SECOND,

HONOKÖHAU STREAM AT GAGING STATION 16620000

30 40 0

5

10

15

0 1 2 3

DISCHARGE, IN CUBIC FEET PER SECOND,

HONOPOU STREAM AT GAGING STATION 16587000

4 5 0

5

10

15

A

C D

B

LEADER LINE FOR 1984–2007 

 DURATION DISCHARGES

GRAPHICAL FIT TO HISTORICAL

 DURATION DISCHARGES

HISTORICAL (1911–17) 

 DURATION DISCHARGES

Figure 31. Relation between concurrent duration discharges for Waikapü Stream and index stations during the 

period 1911–17, and selected duration discharges for Waikapü Stream and index stations during the 1984–2007 

base period, Maui, Hawaiÿi. A, Index station 16614000, Waiheÿe River. B, Index station 16604500, ÿĪao Stream. C, 

Index station 16620000, Honoköhau Stream. D, Index station 16587000, Honopou Stream.

50 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Natural, Undiverted Low-Flow Characteristics 51

Table 15. Selected duration discharges (natural, undiverted conditions) estimated for North Waiehu Stream near an 

altitude of 880 feet during climate years 1984–2007, Maui, Hawaiÿi.

[Mgal/d, million gallons per day]

Flow-duration 

percentile

Duration discharges for North Waiehu Stream using indicated index station, in Mgal/d

(values in parentheses are in cubic feet per second)

Waiheÿe River 

(16614000)

Honoko

−hau 

Stream 

(16620000)

Honopou Stream 

(16587000)

ÿI

−

ao Stream 

(16604500)

Average

(excluding

ÿI

−

ao Stream)

50 3.5 (5.4) 3.1 (4.8) 2.8 (4.4) 3.2 (5.0) 3.2 (4.9)

55 3.4 (5.2) 2.9 (4.5) 2.7 (4.2) 3.0 (4.6) 3.0 (4.6)

60 3.2 (4.9) 2.5 (3.8) 2.7 (4.2) 2.8 (4.4) 2.8 (4.3)

65 2.9 (4.5) 2.3 (3.5) 2.7 (4.2) 2.8 (4.3) 2.7 (4.1)

70 2.5 (3.9) 2.1 (3.2) 2.7 (4.2) 2.7 (4.2) 2.5 (3.8)

75 2.3 (3.6) 1.8 (2.8) 2.7 (4.2) 2.7 (4.2) 2.3 (3.5)

80 2.1 (3.2) 1.6 (2.5) 2.6 (4.0) 2.7 (4.2) 2.1 (3.2)

85 1.9 (2.9) 1.4 (2.2) 2.5 (3.8) 2.7 (4.1) 1.9 (3.0)

90 1.7 (2.6) 1.2 (1.8) 2.2 (3.4) 2.7 (4.1) 1.7 (2.6)

95 1.5 (2.3) 0.97 (1.5) 1.9 (3.0) 2.7 (4.1) 1.5 (2.3)

99 1.1 (1.7) 0.65 (1.0) 1.2 (1.8) 2.7 (4.1) 0.97 (1.5)

Table 16. Selected duration discharges (natural, undiverted conditions) estimated for South Waiehu Stream near an 

altitude of 870 feet during climate years 1984–2007, Maui, Hawaiÿi.

[Mgal/d, million gallons per day]

Flow-duration 

percentile

Duration discharges for South Waiehu Stream using indicated index station, in Mgal/d

(values in parentheses are in cubic feet per second)

Waiheÿe River 

(16614000)

Honoko

−hau 

Stream 

(16620000)

Honopou Stream 

(16587000)

ÿI

−

ao Stream 

(16604500)

Average

(excluding

ÿI

−

ao Stream)

50 3.3 (5.1) 2.4 (3.7) 4.0 (6.2) 4.2 (6.5) 3.2 (5.0)

55 3.0 (4.7) 2.3 (3.5) 3.8 (5.9) 3.7 (5.7) 3.0 (4.7)

60 2.8 (4.3) 2.0 (3.1) 3.4 (5.2) 2.6 (4.0) 2.7 (4.2)

65 2.5 (3.9) 1.9 (3.0) 3.0 (4.6) 2.3 (3.5) 2.5 (3.8)

70 2.2 (3.4) 1.8 (2.8) 2.8 (4.3) 2.1 (3.3) 2.3 (3.5)

75 2.1 (3.2) 1.7 (2.7) 2.3 (3.6) 2.1 (3.2) 2.1 (3.2)

80 1.8 (2.8) 1.7 (2.6) 1.9 (2.9) 2.1 (3.2) 1.8 (2.8)

85 1.6 (2.5) 1.6 (2.5) 1.6 (2.4) 2.0 (3.1) 1.6 (2.5)

90 1.4 (2.2) 1.6 (2.4) 1.2 (1.9) 2.0 (3.1) 1.4 (2.2)

95 1.2 (1.9) 1.4 (2.2) 0.97 (1.5) 2.0 (3.1) 1.2 (1.9)

99 0.84 (1.3) 1.2 (1.8) 0.52 (0.81) 2.0 (3.1) 0.84 (1.3)
Limited concurrent data for the short-term, historical 

gaged sites and index stations were available for analysis. Two 

to five years of concurrent data were available from the gaged 

sites. Most of the concurrent years of data were complete, 

although one year contained 48 days of missing data. The 

limited historical data lead to unquantified uncertainty in 

estimated duration discharges for the 1984–2007 base period.

In some cases, concurrent discharge data from ditchand stream-gaging stations were combined to estimate the 

total natural flow in the stream. Natural flows estimated by 

combining concurrent data in this manner may contain error 

related to losses or ditch return flows in the stream reach 

between the diversion intake and stream-gaging station.

Selected historical daily discharge values may be subject 

to error because the values were based on instantaneous stage 

measurements at specified times during the day. The uncertainty 

associated with this limitation cannot be accurately quantified.

The correlation coefficients between concurrent daily 

discharge values from each short-term, historical gaged site 

and each index station generally were less than 0.3, which 

necessitated use of the graphical-correlation method. The poor 

correlation between concurrent daily discharge values from 

short-term, historical gaged sites and each index station may 

indicate that daily discharge values at the index stations are 

poor predictors of daily discharge at the other sites.

Some of the reported daily discharge values may have 

been affected by diversions or unquantifiable contributions from 

upstream water-development tunnels, which leads to additional 

uncertainty in estimated duration discharges. The estimated 

duration discharges for South Waiehu Stream may need to be 

adjusted upward by 0.06–0.2 Mgal/d (0.1–0.3 ft3

/s) to reflect 

the known diversion upstream of gaging station 16610000 

(Larrison, 1915; Grover and Larrison, 1917a,b, 1918; Wells, 

1961), although the actual diversion rate is poorly known.

In some cases (Waihe‘e River and ‘Īao Stream), data from 

two nearby stream-gaging stations were assumed to represent 

common hydrologic conditions to enhance the amount of data 

available for analysis, even though the stream-gaging stations 

were not colocated. The sites may have been separated by a 

gaining or losing reach, although information is not currently 

available to accurately quantify the gain or loss in flow.

The concurrent periods of record for the short-term gaged 

site and the index sites were wetter than the 1984–2007 base 

period. Thus, curves relating the duration discharges for the 

concurrent periods required extrapolation to obtain some 

of the base-period low-flow estimates, particularly those 

less than the Q90 discharge. These extrapolated low-flow 

estimates contain unquantifiable uncertainty. The low-flow 

characteristics can be determined best by establishing longterm, continuous-record stream-gaging stations in North 

Waiehu, South Waiehu, and Waikapū Streams.

Seepage-Run Measurements

Same-day discharge measurements were made along 

selected reaches of each stream to determine the magnitude 

of streamflow gains or losses over each reach. These same52 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄

Table 17. Selected duration discharges (natural, undiverted conditions) estimated for Waikapu− Stream near an 

altitude of 880 feet during climate years 1984–2007, Maui, Hawaiÿi.

[Mgal/d, million gallons per day]

Flow-duration 

percentile

Duration discharges for Waikapu

− Stream using indicated index station, in Mgal/d

(values in parentheses are in cubic feet per second)

Waiheÿe River 

(16614000)

Honoko

−hau 

Stream 

(16620000)

Honopou Stream 

(16587000)

ÿI

−

ao Stream 

(16604500)

Average

(excluding

ÿI

−

ao Stream)

50 5.8 (8.9) 4.8 (7.5) 6.1 (9.5) 6.3 (9.7) 5.6 (8.6)

55 5.5 (8.5) 4.6 (7.1) 5.9 (9.1) 5.8 (9.0) 5.3 (8.2)

60 5.3 (8.2) 4.1 (6.4) 5.5 (8.5) 5.5 (8.5) 5.0 (7.7)

65 5.1 (7.9) 3.9 (6.1) 5.2 (8.0) 5.4 (8.3) 4.7 (7.3)

70 4.8 (7.5) 3.7 (5.8) 5.0 (7.8) 5.1 (7.9) 4.5 (7.0)

75 4.7 (7.3) 3.6 (5.6) 4.7 (7.2) 5.0 (7.7) 4.3 (6.7)

80 4.5 (7.0) 3.4 (5.3) 4.3 (6.6) 4.8 (7.4) 4.1 (6.3)

85 4.3 (6.7) 3.3 (5.1) 3.9 (6.1) 4.7 (7.2) 3.9 (6.0)

90 4.1 (6.3) 3.1 (4.8) 3.6 (5.6) 4.5 (7.0) 3.6 (5.6)

95 3.7 (5.8) 3.0 (4.6) 3.2 (5.0) 4.4 (6.8) 3.3 (5.1)

99 3.1 (4.8) 2.6 (4.0) 2.3 (3.5) 4.0 (6.2) 2.7 (4.1)
day discharge measurements form what commonly is called a 

seepage run. Seepage-run measurements are used in this study 

to estimate (1) natural streamflow characteristics at ungaged 

sites downstream of existing and historical gaging stations, (2) 

the minimum natural flows necessary to establish continuous 

surface flows from the mountains to the ocean (mauka to makai) 

in the Nā Wai ‘Ehā area (assuming no water is diverted from the 

streams), (3) the reduction of recharge from the stream to the 

underlying groundwater system caused by diversion of surface 

water, and (4) the reduction of physical habitat for native 

stream fauna caused by diversion of surface water. For each 

seepage run, estimated gains or losses in the main channel of 

each stream exclude the contributions from tributaries or ditch 

return flows. For this study, discharge measurements were made 

with acoustic-Doppler velocity (ADV) meters using methods 

described by Rantz and others (1982). 

Seepage-run measurements were made on days when 

flow generally was stable and direct runoff was considered to 

be negligible. In some cases, seepage-run measurements were 

made during ditch-maintenance periods, when diverted water 

was restored to streams for several days. During periods of 

flow restoration, seepage-run measurements were repeated 

on several days to characterize potential changes in loss rates 

over time. The effects of losses related to evaporation and 

transpiration associated with riparian vegetation are small at 

the time and length scales of the seepage-run measurements 

and are not considered.

Because of frequent rainfall within the study area, 

particularly near the mountainous interior areas, scheduling 

seepage-run measurements for periods with zero antecedent 

rainfall was not always possible. Thus, in some cases the 

seepage-run measurements may have been made during a 

recession period when streamflow was slowly declining 

following a period of rainfall. During these recession periods, 

multiple measurements were made, if possible, at the same 

sites (on the same day) in an attempt to bracket the loss 

estimates over a reach for that day. For example, during 

January 14–18, 2008, flow was restored to ‘Īao Stream for 

ditch maintenance and multiple measurements were made 

on January 16, 2008, during a slight recession. On January 

16, 2008, discharge in ‘Īao Stream near an altitude of 395 ft 

was 18.7 Mgal/d (28.9 ft3

/s) at 9:14 a.m., discharge near an 

altitude of 595 ft was 20.4 Mgal/d (31.6 ft3

/s) at 10:55 a.m., 

and discharge near an altitude of 395 ft was 17.5 Mgal/d (27.0 

ft3/s) at 12:35 p.m. (all discharge values were computed from 

the sum of two values, one from a measurement in the stream 

and the second from an estimated inflow of much smaller 

magnitude). Thus, on January 16, 2008, the estimated loss rate 

between altitudes of 595 and 395 ft ranged from 1.7 Mgal/d 

(= 20.4-18.7) to 2.9 Mgal/d (= 20.4-17.5). The estimated loss 

rate may be underestimated if direct runoff, in the form of 

interflow, entered the stream between altitudes of 595 and 395 

ft. Because of uncertainty in the estimated gains and losses 

in a reach, bracketing values for most reaches were defined 

to provide upper and lower estimates of natural streamflow 

characteristics. 

Linear relations were developed between the upstream 

flow (independent variable) and downstream flow (dependent 

variable) for reaches over which gains or losses were 

measured. In most cases, the slope of the linear relation was 

set equal to 1 because the loss showed poor correlation with 

the upstream flow. For reaches in which the slope of the 

linear relation between upstream and downstream flows was 

set equal to 1, loss in the reach is constant and equal to the 

average value. For two reaches (North Waiehu Stream between 

altitudes of 920 and 475 ft and Waiehu Stream between 

altitudes of 190 and 20 ft) in which upstream and downstream 

flows were measured for a relatively wide range of conditions, 

the linear relation was defined by regression. Linear regression 

was used for these two reaches, even though limited data were 

available, because it produced a more reasonable estimate 

of loss over the range of available measurements relative to 

using the average loss. In terms of the loss in the reach, (1) a 

slope less than 1 indicates that loss in the reach increases as 

the upstream flow increases; (2) a slope equal to 1 indicates a 

constant loss in the reach, regardless of upstream flow; and (3) 

a slope greater than 1 indicates that loss in the reach decreases 

as the upstream flow increases. A slope less than 1 is expected 

in losing reaches that remain hydraulically disconnected from 

groundwater as the upstream flow increases. A slope greater 

than 1 may exist in losing reaches within which the hydraulic 

connection to groundwater is enhanced as the upstream flow 

increases. 

Available seepage-run measurements from Waihe‘e 

River indicate a gaining reach between the diversion intakes 

for Waihe‘e and Spreckels Ditches and a generally losing 

reach between the intake for Spreckels Ditch and an altitude 

of 45 ft, although localized gaining reaches may exist (fig. 

32). Seepage-run measurements indicate that North and 

South Waiehu, ‘Īao, and Waikapū Streams mainly lose water 

downstream of their uppermost diversions, although localized 

gaining reaches may exist in each of these streams (figs. 33–35). 

Measured loss rates in some reaches of these streams exceeded 

1 Mgal/d per mile of stream (1.5 ft3

/s per mile) (figs. 32–35). 

Measured losses, in terms of percentage of upstream flow, 

commonly exceeded 10 percent in reaches of Waiehu, ‘Īao, 

and Waikapū Streams but were less than 10 percent in reaches 

of Waihe‘e River. In some stream reaches small relative 

differences between measured upstream and downstream flows 

reflect potential uncertainty associated with characterizing 

losses. If errors associated with discharge measurements 

are less than 5 percent of the actual discharge values, then 

according to the rules of error propagation, losses less than 

7 percent of the discharge in the reach of interest may not be 

reliably detected (LaBaugh and Rosenberry, 2008). Similarly, 

if errors associated with discharge measurements are less than 

8 percent of the actual discharge values, then losses less than 

11 percent of the discharge in the reach of interest may not 

be reliably detected. Repeated seepage-run measurements 

in a stream reach increase the level of confidence in, and the 

reliability of, loss estimates in the reach. 

Natural, Undiverted Low-Flow Characteristics 53
0

5

10

15

20

25

0

0

-1

1

2

3

4

5

10

15

20

30

25

30

35

40

50

45

DISCHARGE, IN MILLION GALLONS PER DAY

DISCHARGE, IN CUBIC FEET PER SECOND LOSS RATE, IN CUBIC FEET PER SECOND PER MILE OF STREAM

Field 1 diversion

intake altitude

Spreckels Ditch

intake altitude

Waiheÿe Ditch

intake altitude

300 200 100 0

ALTITUDE, IN FEET RELATIVE TO MEAN SEA LEVEL

600 500 400

-2

-1

0

1

2

3

4

5

6

7

LOSS RATE, IN MILLION GALLONS PER DAY PER MILE OF STREAM

A

B

Measured discharge

Calculated discharge from multiple measurements

points indicate upstream and downstream

altitudes of reach; vertical position of line

indicates loss rate over the reach

Note: negative values indicate gain

06/16/2004

06/16/2004

02/27/2008

12/02/2008

12/04/2008

11/21/2008

11/20/2008

12/12/2006

02/28/2008

12/11/2006

02/29/2008

02/28/2008

02/27/2008

02/26/2008; 02/28/2008

02/26/2008

12/02/2008

11/21/2008

12/02/2008

12/01/2008

02/27/2008; 02/29/2008

02/28/2008

01/17/2007

Figure 32. Seepage-run measurements over selected reaches, Waiheÿe River, Maui, Hawaiÿi. A, Discharge 

variation with altitude. B, Loss-rate variation with altitude. Repeat measurement from 02/26/2008 at an altitude 

of 285 feet not shown.

54 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
0.0

0.5

1.0

1.5

2.0

0.0

0.5

1.0

1.5

2.5

2.0

2.5

3.0

4.0

3.5

-0.2

0.0

0.2

0.4

0.8

0.6

1.2

1.0

-0.5

0.0

0.5

1.0

1.5

2.0

1,000 900 800 700 600 500 400 300 200 100 0

DISCHARGE, IN MILLION GALLONS PER DAY

DISCHARGE, IN CUBIC FEET PER SECOND LOSS RATE, IN CUBIC FEET PER SECOND PER MILE OF STREAM

ALTITUDE, IN FEET RELATIVE TO MEAN SEA LEVEL

LOSS RATE, IN MILLION GALLONS PER DAY PER MILE OF STREAM

Spreckels Ditch

intake altitude (South Waiehu Stream)

North Waiehu Ditch

intake altitude

ÿauwai intake altitudes

(South Waiehu Stream)

A

B

North Waiehu Stream

South Waiehu Stream

Waiehu Stream

Measured discharge

Calculated discharge from multiple measurements

Note: negative values indicate gain

points indicate upstream and downstream altitudes of reach;

vertical position of line indicates loss rate over the reach

03/14/2008

03/14/2008

07/27/2006

07/27/2006

08/17/2005

12/19/2007

07/28/2008

10/10/2006

08/17/2005

03/12//2008

03/07/2007

03/06/2007

03/13/2008

08/29/2007

11/17/2008

07/26/2006

03/06/2007

03/07/2007

03/11/2008

03/12/2008

03/10/2008; 03/13/2008

03/10/2008

03/12/2008

03/11/2008

03/13/2008

Figure 33. Seepage-run measurements over selected reaches, Waiehu Stream, Maui, Hawaiÿi. A, Discharge 

variation with altitude. B, Loss-rate variation with altitude.

Natural, Undiverted Low-Flow Characteristics 55
0

5

10

15

20

25

0

5

10

15

20

30

25

30

35

40

50

45

-3

-2

-1

0

1

2

5

3

4

-6

-4

-2

0

2

4

6

8

800 700 600 500 400 300 200 100 0

DISCHARGE, IN MILLION GALLONS PER DAY

DISCHARGE, IN CUBIC FEET PER SECOND LOSS RATE, IN CUBIC FEET PER SECOND PER MILE OF STREAM

ALTITUDE, IN FEET RELATIVE TO MEAN SEA LEVEL

LOSS RATE, IN MILLION GALLONS PER DAY PER MILE OF STREAM

Spreckels Ditch

intake altitude

ÿauwai

intake altitude

ÿÏao-Waikapü and ÿÏao-Mäniania

 Ditches, common intake altitude

A

B

Measured discharge

Calculated discharge from multiple measurements

Points indicate upstream and downstream

altitudes of reach; vertical position of

line indicates loss rate over the reach

Note: negative values indicate gain

02/11/2008

02/12/2008

02/13/2008

02/14/2008

02/15/2008

01/16/2008

01/17/2008

01/18/2008

01/18/2007

02/13/2007

02/14/2007

09/21/2004 09/21/2004 09/21/2004

07/24/2006

10/11/2006

01/16/2007

08/30/2007

09/21/2007

12/14/2006

Figure 34. Seepage-run measurements over selected reaches, ÿĪao Stream, Maui, Hawaiÿi. A, Discharge variation with altitude. B, Loss-rate variation with altitude.

56 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
0 0

6

4

2

8

10

12

16

14

5

10

15

25

20

-2

-1

0

1

-1

0

1

2

2

4

3

DISCHARGE, IN MILLION GALLONS PER DAY

DISCHARGE, IN CUBIC FEET PER SECOND LOSS RATE, IN CUBIC FEET PER SECOND PER MILE OF STREAM

600 400 200 0

ALTITUDE, IN FEET RELATIVE TO MEAN SEA LEVEL

1,200 1,000 800

LOSS RATE, IN MILLION GALLONS PER DAY PER MILE OF STREAM

ÿauwai, Waiheÿe, and Reservoir 6 Ditch

intake altitudes

South Side Ditch

intake altitude

Everett Ditch

intake altitude

A

B

Measured discharge

Calculated discharge from multiple measurements

points indicate upstream and downstream

altitudes of reach; vertical position of

line indicates loss rate over the reach

Note: negative values indicate gain

03/18/2004

08/22/2006

10/28/2004

10/28/2004

04/29/2008

04/30/2008

04/28/2008 11/15/2007

08/02/2007

05/03/2007

04/30/2008

11/15/2007

05/03/20007

12/13/2006

09/06/2006

05/03/2007

04/02/2007

03/13/2009

01/29/2009

Figure 35. Seepage-run measurements over selected reaches, Waikapu ̄ Stream, Maui, Hawaiÿi. A, Discharge 

variation with altitude. B, Loss-rate variation with altitude.

Natural, Undiverted Low-Flow Characteristics 57
Waiheÿe River

Seepage-run measurements were made during typical 

diverted conditions, as well as during periods of about a week 

in duration when flow was partially or almost fully restored 

to Waihe‘e River. Temporary periods of flow restoration in 

Waihe‘e River occurred during February, November, and 

December 2008. Flow was restored to Waihe‘e River near an 

altitude of 560 ft (February 2008), near an altitude of 315 ft 

(November 2008), or near both altitudes (December 2008). 

Seepage-run measurements were made about one to several 

days following the initiation of the flow restorations. Near 

an altitude of 45 ft in Waihe‘e River, increased streamflow 

caused by the temporary restorations was observed from 

about (1) 3:00 p.m. on February 24, 2008, before the 

seepage-run measurements during February 26–29, 2008; 

(2) 5:30 p.m. on November 16, 2008, before the seepage-run 

measurements of November 20–21, 2008; and (3) 5:30 p.m. 

on November 30, 2008, before the seepage-run measurements 

of December 1–4, 2008. Rainfall occurred on November 18 

and 19, 2008, before the measurements of November 20–21, 

2008, and caused a rise in flow in Waihe‘e River, although 

measurements used to characterize gains and losses in 

Waihe‘e River were not affected by changing stage. 

Stream Altitudes of 585 to 400 Feet

Seepage-run measurements between altitudes of 585 and 

400 ft indicate a gaining reach in Waihe‘e River, downstream 

of the intake for Waihe‘e Ditch and upstream of the intake for 

Spreckels Ditch. Available measurements indicate an average 

gain of about 0.39 Mgal/d (0.61 ft3/s) in this reach of Waihe‘e 

River. Measured gains between altitudes of 585 and 400 ft 

ranged from 0.03 to 0.68 Mgal/d (0.05 to 1.05 ft3/s), and this 

range is assumed to bracket the true gain in the reach (fig. 32). 

Seepage-run measurements between altitudes of 585 and 400 ft 

are available for diverted conditions, when flow was less than 

about 2 Mgal/d (3 ft3/s). In addition, seepage-run measurements 

made at altitudes of 530 and 445 ft are available for nearly 

undiverted conditions. On February 28, 2008, when nearly all 

of the water diverted from Waihe‘e River near an altitude of 

600 ft was returned to Waihe‘e River near an altitude of 560 ft, 

the measured gain between altitudes of 530 and 445 ft was 0.45 

Mgal/d (0.70 ft3

/s) (fig. 32). 

Huluhulupueo Stream is a tributary of Waihe‘e River and 

enters the north side of the main stream near an altitude of about 

490 ft. Available discharge measurements from Huluhulupueo 

Stream range from 0.033 to 0.50 Mgal/d (0.051 to 0.78 ft3/s), 

with an average flow of 0.17 Mgal/d (0.27 ft3/s), and do not 

indicate a strong correlation between the tributary inflow and 

corresponding daily mean discharge of Waihe‘e River at gaging 

station 16614000. Two small tributaries on the south side of 

Waihe‘e River, between altitudes of about 500 and 560 ft, 

contribute about 0.1 Mgal/d (0.2 ft3

/s). 

Stream Altitudes of 400 to 100 Feet

Available seepage-run measurements downstream of an 

altitude of 400 ft, downstream of the Spreckels Ditch intake, 

indicate that Waihe‘e River generally loses water, although 

localized gaining reaches may exist immediately downstream 

of the dams associated with the intakes for Spreckels and Field 

1 Ditches. For the purposes of this study, the reach between 

altitudes of 400 and 360 ft is assumed to neither gain nor lose 

water, although the stream may gain a small amount of water 

downstream of the dam for Spreckels Ditch. On the basis 

of limited data, the loss between altitudes of 360 and 310 ft 

(including the measurements between altitudes of 360 and 320 

ft) ranged from about 0.19 to 0.47 Mgal/d (0.30 to 0.72 ft3/s), 

and the average of the maximum and minimum loss values is 

0.33 Mgal/d (0.51 ft3/s) (fig. 32). The loss between altitudes 

of 310 and 270 ft ranged from 0.28 to 0.45 Mgal/d (0.43 to 

0.70 ft3

/s), and the average of the maximum and minimum loss 

values is 0.36 Mgal/d (0.56 ft3

/s) (fig. 32). 

Gains or losses between altitudes of about 270 and 100 ft 

were not directly measured, because of numerous return flows 

that were considered too difficult to accurately quantify. For this 

study, the loss between altitudes of about 270 and 100 ft was 

estimated on the basis of data from upstream and downstream 

reaches. On the basis of measurements from three separate 

days, the loss rate between altitudes of 310 and 270 ft ranged 

from 0.84 to 1.4 Mgal/d per mile of stream (1.3 to 2.1 ft3/s per 

mile), and the average of the maximum and minimum loss rates 

is about 1.1 Mgal/d per mile of stream (1.7 ft3/s per mile). (For 

the reach between altitudes of 310 and 270 ft, loss rates were 

measured on November 20 and 21, 2008, but only data from 

November 21, 2008, were included in computing the average 

to avoid giving too much weight to potentially nonindependent 

values.) The loss rate between altitudes of 100 and 45 ft ranged 

from -0.20 to 2.2 Mgal/d per mile of stream (-0.31 to 3.4 ft3

/s 

per mile), with an average loss rate of about 0.71 Mgal/d per 

mile of stream (1.1 ft3/s per mile). Using the average loss rates 

from the upstream and downstream reaches and a reach length 

of about 4,700 ft between altitudes of 270 and 100 ft, the 

estimated loss between altitudes of 270 and 100 ft ranges from 

about 0.28 to 1.58 Mgal/d (0.43 to 2.44 ft3

/s) and averages about 

0.80 Mgal/d (1.25 ft3/s). (The minimum loss was estimated 

from the average of the minimum loss rates from the upstream 

and downstream reaches. Similarly, the maximum loss was 

estimated from the average of the maximum loss rates from the 

upstream and downstream reaches.)

Seepage-run measurements from February 26–29, 2008, 

indicate a gaining reach between altitudes of 390 and 285 

ft, although the gain could not be confirmed by subsequent 

measurements during November 20–21 and December 1–4, 

2008. Furthermore, many dry reaches and no obvious significant 

gaining reaches were observed between altitudes of 390 and 

285 ft during a reconnaissance survey on August 12, 2008. 

Thus, measurements made during February 26–29, 2008, near 

altitudes of 390 and 285 ft may not accurately reflect losses or 

gains within this reach. 

58 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Stream Altitudes of 100 to 45 Feet

In general, the reach of Waihe‘e River between 

altitudes of 100 and 45 ft loses water, although seepage-run 

measurements from February 28, 2008, indicate no gain or 

loss and measurements from December 4, 2008, indicate a 

small gain of less than 1 percent of the upstream flow. The 

difference in flow between altitudes of 100 and 45 ft ranged 

from a gain of 0.065 Mgal/d (0.10 ft3

/s) to a loss of 0.71 

Mgal/d (1.10 ft3/s). Because of the wide range of differences 

between upstream and downstream flows, the average 

difference was estimated from all available data and indicated 

a loss of about 0.23 Mgal/d (0.35 ft3/s) (fig. 32). 

Waiehu Stream

Seepage-run measurements were made on selected reaches 

of North Waiehu Stream, South Waiehu Stream, and Waiehu 

Stream. The seepage-run measurements most representative of 

natural-flow conditions in North Waiehu Stream and Waiehu 

Stream were made during periods when flow was temporarily 

restored to North Waiehu Stream during March 2007 and 

March 2008. 

North Waiehu Stream

During March 2007 and March 2008, diverted flow was 

temporarily restored to North Waiehu Stream through a release 

gate just downstream of the diversion dam for the North Waiehu 

Ditch. Seepage-run measurements were made about one to 

several days following the initiation of the temporary flow 

restorations. (North Waiehu Stream was flowing near an altitude 

of 475 ft during March 4 and 5, 2007, before the seepage-run 

measurements on March 6 and 7, 2007. North Waiehu Stream 

was flowing near an altitude of 475 ft after 2:00 p.m. on March 

9, 2008, before the seepage-run measurements on March 10–14, 

2008.) Data from the March 14, 2008, seepage run appear to 

have been affected by rainfall and were not used in the analysis.

Stream Altitudes of 920 to 475 Feet

During the periods of flow restoration in March 2007 and 

March 2008, the measured natural flow in North Waiehu Stream 

near an altitude of 920 ft ranged from 2.18 to 2.36 Mgal/d 

(3.37 to 3.65 ft3/s). The overall loss between altitudes of 920 

and 475 ft ranged from 0.91 to 1.22 Mgal/d (1.41 to 1.89 ft3/s), 

representing 41 to 52 percent of the available upstream flow 

(fig. 33). The overall loss rates between altitudes of 920 and 475 

ft ranged from 0.84 to 1.1 Mgal/d per mile of stream (1.3 to 1.7 

ft3/s per mile). On March 10, 11, 12, and 13, 2008, the loss rates 

between altitudes of 920 and 475 ft were, respectively, 1.1, 0.97, 

1.1, and 1.0 Mgal/d per mile of stream (1.7, 1.5, 1.7, and 1.6 

ft3/s per mile). 

For dry-weather conditions during the 2006–2008 datacollection period, diversion of water from North Waiehu Stream 

near an altitude of 880 ft commonly caused the stream to be 

dry (zero flow) at some point upstream of an altitude of 450 ft, 

where an existing road crosses the stream. Visual observations 

on August 17, 2005, and October 10, 2006, indicated zero flow 

at an altitude of about 625 ft. On December 19, 2007, measured 

flow near an altitude of 820 ft was 0.52 Mgal/d (0.81 ft3

/s) and 

zero flow was observed near an altitude of 450 ft. On July 1, 

2008, measured flow near an altitude of 820 ft was 1.00 Mgal/d 

(1.55 ft3/s) and flow was observed at least as far downstream as 

an altitude of 490 ft. Thus, a flow between about 0.52 and 1.00 

Mgal/d (0.81 and 1.55 ft3/s) near an altitude of 820 ft is required 

to initiate flow near altitudes of 490 to 450 ft, and these flows 

are used to bracket the flow at an altitude of 920 ft necessary to 

initiate flow at an altitude of 475 ft (fig. 36A). 

For the losing reach between stream altitudes of 920 

and 475 ft, the regression line fit to the available pairs of 

upstream and downstream flows has a slope less than 1 (fig. 

36A), indicating that the loss increases as the upstream flow 

increases. For the flow-restoration period during March 

2008, only data from March 13, 2008, were used in the linear 

regression analysis. Data from March 13, 2008, were collected 

toward the end of the March 2008 flow-restoration period and 

were considered most representative for estimating loss in the 

reach. Data from March 10–12, 2008, were collected during 

the same flow-restoration period, show similar losses, and do 

not represent independent conditions. Therefore, they were 

excluded from the regression analysis.

Because the relation between upstream and downstream 

flows in the reach between altitudes of 920 and 475 ft is poorly 

known, bracketing lines were developed to describe the range 

of downstream flows that are possible for a given upstream 

flow (fig. 36A). The upper bracketing line was established by 

connecting the two points that define the upper limit of the 

available data. The lower bracketing line was established by 

using the linear regression slope and forcing the line to pass 

through the point that causes the line to define the lower limit of 

the available data. 

For this study, the natural discharge in North Waiehu 

Stream was measured near an altitude of 920 ft, upstream of the 

North Waiehu Ditch intake, which is near an altitude of 880 ft. 

Because the discharge-measurement site near an altitude of 920 

ft is within a few hundred feet of the North Waiehu Ditch intake 

near an altitude of 880 ft, the natural, undiverted discharges 

at altitudes of 920 and 880 ft in North Waiehu Stream are 

considered equal for this study. 

Stream Altitudes of 475 to 280 Feet

Same-day measurements at altitudes of 475 and 280 ft are 

available only for a small range of upstream flows. On the basis 

of available data, the loss between altitudes of 475 and 280 ft 

ranged from about 0.36 to 0.59 Mgal/d (0.55 to 0.91 ft3/s). The 

average loss from measurements on March 7, 2007, and March 

13, 2008, was 0.39 Mgal/d (0.61 ft3/s). Available data from 

March 7, 2007, and March 13, 2008, were considered most 

Natural, Undiverted Low-Flow Characteristics 59
0.0

0.0 0.5 1.0 1.5 2.0 2.5

0.5 1.0 1.5 2.0 2.5

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

0.0

0.5

1.0

1.5

2.0

2.5

3.5

3.0

4.0

UPSTREAM DISCHARGE NEAR AN ALTITUDE OF 920 FEET, IN CUBIC FEET PER SECOND

DOWNSTREAM DISCHARGE NEAR AN ALTITUDE OF 475 FEET,

IN CUBIC FEET PER SECOND

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

0.0

0.5

1.0

1.5

0.0

0.5

1.0

1.5

2.0

2.5

0.0

0.5

1.0

1.5

2.0

2.5

2.0

2.5

3.5

3.0

4.0

UPSTREAM DISCHARGE NEAR AN ALTITUDE OF 190 FEET, IN CUBIC FEET PER SECOND

UPSTREAM DISCHARGE NEAR AN ALTITUDE OF 920 FEET, IN MILLION GALLONS PER DAY

UPSTREAM DISCHARGE NEAR AN ALTITUDE OF 190 FEET, IN MILLION GALLONS PER DAY

DOWNSTREAM DISCHARGE NEAR AN ALTITUDE OF 20 FEET,

IN CUBIC FEET PER SECOND

DOWNSTREAM DISCHARGE NEAR AN ALTITUDE OF 475 FEET,

IN MILLION GALLONS PER DAY

DOWNSTREAM DISCHARGE NEAR AN ALTITUDE OF 20 FEET,

IN MILLION GALLONS PER DAY

A

B

Data from subreach between

altitudes of 190 and 50 feet

Data from subreach between

altitudes of 190 and 50 feet,

extrapolated to entire reach

UPPER BRACKETING ESTIMATE

RELATION FROM AVAILABLE DATA

LOWER BRACKETING ESTIMATE

DATA USED TO DEFINE RELATION

DATA NOT USED TO DEFINE RELATION

DATA FROM A SUBREACH, EXTRAPOLATED

 TO ENTIRE REACH

Figure 36. Relation between undiverted streamflows at an upstream and downstream site, Waiehu Stream, Maui, Hawaiÿi. 

A, Altitudes of 920 and 475 feet, North Waiehu Stream. B, Altitudes of 190 and 20 feet, Waiehu Stream. (Discharge near an 

altitude of 920 feet in North Waiehu Stream is assumed to be equal to discharge near an altitude of 880 feet.)

60 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
representative for estimating the loss during their respective 

flow-restoration periods. 

Stream Altitudes of 280 to 220 Feet

Downstream of an altitude of about 280 ft to the 

confluence of North and South Waiehu Streams near an altitude 

of 220 ft, North Waiehu Stream appears to gain water. The 

source of the gain may be related to shallow groundwater or 

subsurface leakage from the Spreckels Ditch pipeline beneath 

and near North Waiehu Stream. Irrigation water returned to the 

stream also may be a source of the apparent gain. On the basis 

of seepage-run measurements from July 27, 2006, the average 

gain between altitudes of 260 and 225 ft is about 1 percent 

of the flow in North Waiehu Stream near an altitude of 900 ft 

measured 2 days earlier. (For the purposes of this study, the flow 

near an altitude of 900 ft is assumed to be equal to the flow near 

an altitude of 920 ft, which is reasonable given that the two sites 

are separated by less than 200 ft of stream length. Furthermore, 

the gain between altitudes of 260 and 225 ft is assumed to be 

representative of the gain between altitudes of 280 and 220 

ft.) Measurements are not available to define a range of gains 

in this reach. The bracketing values for the gain in this reach 

are assumed to range from 0 to 2 percent of the flow in North 

Waiehu Stream near an altitude of 920 ft, and these values 

represent -100 to +100 percent of the estimate of 1 percent of 

the flow near an altitude of 920 ft.

South Waiehu Stream

The limited seepage-run data that were collected for South 

Waiehu Stream indicate that South Waiehu Stream neither gains 

nor loses large volumes of water between altitudes of 870 and 

535 ft. South Waiehu Stream loses about 1 Mgal/d (1.5 ft3/s) 

between altitudes of 535 and 280 ft. 

Stream Altitudes of 870 to 670 Feet

On the basis of measurements made on November 17, 

2008, the estimated loss between altitudes of 870 and 670 ft 

in South Waiehu Stream was only 0.03 Mgal/d (0.05 ft3/s), 

indicating a relatively neutral reach that does not gain or lose a 

large volume of water. Measurements are not available to define 

a range of losses in this reach. The bracketing values for the loss 

in this reach are assumed to be 0 to 0.06 Mgal/d (0 to 0.1 ft3/s), 

and these values represent -100 to +100 percent of the estimate 

of 0.03 Mgal/d (0.05 ft3/s). 

Stream Altitudes of 670 to 535 Feet

On the basis of measurements made on August 29, 2007, 

the estimated loss between altitudes of 670 and 535 ft in South 

Waiehu Stream was only 0.04 Mgal/d (0.06 ft3

/s), indicating a 

relatively neutral reach that does not gain or lose a large volume 

of water. Measurements are not available to define a range of 

losses in this reach. The bracketing values for the loss in this 

reach are assumed to be 0 to 0.08 Mgal/d (0 to 0.12 ft3/s), and 

these values represent -100 to +100 percent of the estimate of 

0.04 Mgal/d (0.06 ft3/s). Assuming a uniform loss per mile of 

stream length, about 24 percent of the loss takes place between 

altitudes of 670 and 635 ft, and the remaining 76 percent of the 

loss takes place between altitudes of 635 and 535 ft.

Stream Altitudes of 535 to 405 Feet

Between altitudes of 635 and 405 ft, the measured loss 

on July 26, 2006, was 0.59 Mgal/d (0.92 ft3/s). Available 

information on losses between altitudes of 670 and 405 ft 

indicates that nearly all of the measured loss in the reach 

between altitudes of 635 and 405 ft takes place downstream 

of an altitude of 535 ft. The estimated loss between altitudes 

of 635 and 535 ft is about 0.03 Mgal/d (0.05 ft3/s) (see 

previous discussion for stream altitudes of 670 to 535 ft), 

and the estimated loss between altitudes of 535 and 405 ft is 

0.56 Mgal/d (0.87 ft3/s). Measurements are not available to 

define a range of losses in this reach. The bracketing values 

for the loss in the reach between altitudes of 535 and 405 ft 

are assumed to be 0 to 1.12 Mgal/d (0 to 1.74 ft3

/s), and these 

values represent -100 to +100 percent of the estimate of 0.56 

Mgal/d (0.87 ft3

/s).

Stream Altitudes of 405 to 280 Feet

On the basis of measurements made on July 27, 2006, the 

estimated loss between altitudes of 405 and 280 ft in South 

Waiehu Stream was 0.35 Mgal/d (0.54 ft3/s). Measurements 

are not available to define a range of losses in this reach. The 

bracketing values for the loss in this reach are assumed to be 0 

to 0.70 Mgal/d (0 to 1.08 ft3

/s), and these values represent -100 

to +100 percent of the estimate of 0.35 Mgal/d (0.54 ft3/s).

Stream Altitudes of 280 to 220 Feet

Measurements are not available to characterize gains or 

losses in the reach of South Waiehu Stream between an altitude 

of 280 ft and the confluence with North Waiehu Stream near 

an altitude of 220 ft. For the purposes of this study, this reach 

is assumed to neither gain nor lose water, although the stream 

may gain a small amount of water downstream of the dam for 

Spreckels Ditch. 

Waiehu Stream

Limited seepage-run measurements were made on Waiehu 

Stream upstream of an altitude of 190 ft. Available seepage-run 

Natural, Undiverted Low-Flow Characteristics 61
measurements downstream of an altitude of 190 ft indicate that 

Waiehu Stream loses water in its lower reaches. 

Stream Altitudes of 220 to 190 Feet

Seepage-run measurements from August 17, 2005, indicate 

a possible gaining reach in Waiehu Stream between an altitude 

of 220 ft, near the confluence of North and South Waiehu 

Streams, and an altitude of 65 ft. Although measurements are 

not available to definitively constrain the location of the gaining 

reach, the presence of a gaining reach between the confluence 

of North and South Waiehu Streams and an altitude of 190 ft is 

consistent with visual observations of seepage from the stream 

banks upstream of an altitude of 190 ft and available data that 

indicate a losing reach downstream of an altitude of 190 ft. 

On the basis of seepage-run measurements from August 

17, 2005, the average gain between altitudes of 220 and 65 ft 

is about 5 percent of the flow in North Waiehu Stream near an 

altitude of 920 ft. For the purposes of this study, all of the gain 

is attributed to the reach between altitudes of 220 and 190 ft, 

and losses between altitudes of 190 and 65 ft are assumed to be 

small. Measurements are not available to define a range of gain 

in the reach between altitudes of 220 and 190 ft. The bracketing 

values for the gain in this reach are assumed to range from 0 to 

10 percent of the flow in North Waiehu Stream near an altitude 

of 920 ft, and these values represent -100 to +100 percent of the 

estimate of 5 percent of the flow near an altitude of 920 ft.

Stream Altitudes of 190 to 20 Feet

During periods of flow restoration to North Waiehu 

Stream in March 2007 and March 2008, seepage-run 

measurements were made in Waiehu Stream downstream of 

an altitude of 190 ft. During these periods of flow restoration, 

measured flow in Waiehu Stream near an altitude of 190 ft 

ranged from 0.90 to 1.45 Mgal/d (1.40 to 2.24 ft3/s). On March 

6 and 7, 2007, upstream flows near an altitude of 190 ft were 

1.23 and 1.45 Mgal/d (1.91 and 2.24 ft3/s), respectively, and 

losses between 190 and 50 ft were 0.39 and 0.42 Mgal/d (0.60 

and 0.65 ft3

/s), or about 0.41 and 0.45 Mgal/d per mile of 

stream (0.64 and 0.70 ft3

/s per mile). Measured losses between 

altitudes of 190 and 50 ft represent about 30 percent of the 

upstream flow at 190 ft. On March 12 and 13, 2008, upstream 

flows near an altitude of 190 ft were 0.99 and 0.90 Mgal/d 

(1.53 and 1.40 ft3/s), respectively, and losses between 190 and 

20 ft were 0.37 and 0.33 Mgal/d (0.58 and 0.51 ft3

/s), or about 

0.34 and 0.29 Mgal/d per mile of stream (0.52 and 0.45 ft3/s 

per mile). Measured losses between altitudes of 190 and 20 ft 

represent about 37 percent of the upstream flow at 190 ft.

The increase in loss from March 6 to March 7, 2007, may 

reflect a higher discharge at the upstream site near an altitude 

of 190 ft on March 7 (1.45 Mgal/d; 2.24 ft3/s) relative to 

March 6 (1.23 Mgal/d; 1.91 ft3/s). The reduction in loss from 

March 12 to March 13, 2008, may reflect a lower discharge at 

the upstream site near an altitude of 190 ft on March 13 (0.90 

Mgal/d; 1.40 ft3

/s) relative to March 12 (0.99 Mgal/d; 1.53 

ft3/s), or a reduction in loss as the streambed became saturated. 

On September 21, 2007, measured flow near an altitude of 

190 ft was 0.26 Mgal/d (0.40 ft3/s) and zero flow was observed 

(based on photographic data from a mounted camera) near an 

altitude of 20 ft. On April 2, 2007, measured flow near an altitude 

of 190 ft was 0.31 Mgal/d (0.48 ft3/s) and nonzero flow (very low 

flow, based on photographic data from a mounted camera) was 

observed near an altitude of 20 ft. Thus, a flow between about 

0.26 and 0.31 Mgal/d (0.40 and 0.48 ft3

/s) near an altitude of 190 

ft is required to initiate flow near an altitude of 20 ft. No known 

diversions exist downstream of the confluence of North and 

South Waiehu Streams. 

For the losing reach between stream altitudes of 190 

and 20 ft, the regression line fit to the available pairs of 

upstream and downstream flows has a slope less than 1 (fig. 

36B), indicating that the loss increases as the upstream flow 

increases. For the flow-restoration period during March 

2008, only data from March 12 were used in the linear 

regression analysis. Data from March 12 were considered 

most representative for estimating loss in the reach because 

of the timing of the upstream and downstream measurements 

during a slight flow-recession period. On March 12 the 

upstream measurement was made about 2 hours before the 

downstream measurement, whereas on March 13 the upstream 

and downstream measurements were made at about the same 

time. Thus, the loss estimated from measurements on March 

13, 2008, could underestimate the actual loss. 

Because the relation between upstream and downstream 

flows in the reach between altitudes of 190 and 20 ft is poorly 

known, bracketing lines were developed to describe the range 

of downstream flows that are possible for a given upstream 

flow (fig. 36B). The lower bracketing line was established 

using the same slope as the linear-regression slope, and it was 

forced to pass through the March 7, 2007, data (upstream flow 

at 190 ft and downstream flow at 50 ft) that were extrapolated 

to the entire reach from altitudes of 190 to 20 ft. For this case, 

the extrapolation was made by assuming that the loss rate is 

linearly related to flow. The upper bracketing line also used 

the same slope as the linear-regression slope, and the intercept 

was defined by assuming the regression line passes through 

the data from March 13, 2008. 

ÿĪao Stream

Seepage-run measurements were made during typical 

diverted conditions, as well as during periods when flow 

was partially or almost fully restored to ‘Īao Stream. The 

seepage-run measurements most representative of naturalflow conditions in ‘Īao Stream were made when flow was 

temporarily restored to ‘Īao Stream during December 14, 

2006; January 18, 2007; January 16–18, 2008; and February 

11–15, 2008. 

62 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Variability in measured loss rates for a reach may reflect 

variable antecedent conditions or variable flow rates among 

the different measurement days. On the basis of available 

antecedent photographic data near an altitude of 370 ft, ‘Īao 

Stream was flowing at various rates before the discharge 

measurements near altitudes of 595 and 395 ft on December 

14, 2006 (flowing since November 27, 2006), and on January 

16–18, 2008, and February 11–15, 2008 (flowing since 

December 2, 2007). On the basis of available antecedent 

photographic data near an altitude of 50 ft, ‘Īao Stream was 

flowing at various rates before the discharge measurements 

near altitudes of 220 and 35 ft on January 18, 2007 (since 

January 17, 2007), and February 13–14, 2008 (since January 

26, 2008). 

Downstream of an altitude of 780 ft, ‘Īao Stream 

generally loses water, although localized gaining reaches 

exist. For example, a pool at the base of a near-vertical drop 

in the steam channel near an altitude of 370 ft persists during 

dry-weather conditions because of shallow subsurface flow 

and seepage. An apparent gaining reach between altitudes 

of 310 and 250 ft in a concrete-lined channel is caused by 

subsurface water that emerges through cracks and holes in 

the concrete. Mapped tunnels and a spring on the north side 

of ‘Īao Stream between altitudes of about 400 and 250 ft 

are consistent with observed gains in this area (Stearns and 

Macdonald, 1942).

Stream Altitudes of 780 to 725 Feet

Seepage-run measurements for subreaches between 

altitudes of 780 and 725 ft indicate a gaining reach in ‘Īao 

Stream, downstream of the intake for the ‘Īao-Waikapū and 

‘Īao-Māniania Ditches, although available measurements are 

for diverted conditions when flow was less than 0.65 Mgal/d 

(1 ft3/s). On the basis of measurements from September 21, 

2004; July 24, 2006; October 11, 2006; and January 16, 

2007, subreaches between altitudes of 780 and 725 ft gained 

between 1.2 and 2.2 percent of the upstream, undiverted 

flow near an altitude of 780 ft (gaging station 16604500), 

with an average gain of 1.8 percent. In addition to the gain 

in the main stream channel, an unnamed tributary that 

enters the south side of ‘Īao Stream near an altitude of 710 

ft contributes inflow. Available discharge values for this 

tributary range from 0.03 to 0.11 Mgal/d (0.04 to 0.17 ft3

/s), 

with an average flow of about 0.05 Mgal/d (0.07 ft3/s), and 

do not indicate a strong correlation with the corresponding 

daily mean discharge from ‘Īao Stream at gaging station 

16604500.

Stream Altitudes of 725 to 595 Feet

Seepage-run measurements between altitudes of 725 and 

610 ft indicate a losing reach in ‘Īao Stream, although these 

measurements are available only for diverted conditions, 

when flow was less than 0.46 Mgal/d (0.71 ft3/s). On the 

basis of discharge measurements from July 24 and October 

11, 2006, the estimated lower bracketing value of loss in this 

reach is about 0.32 Mgal/d (0.50 ft3

/s). By extrapolating the 

loss rate, assuming uniform loss per mile of stream length, 

from the reach between altitudes of 595 and 395 ft, which 

generally has a higher loss rate than the reach between 

altitudes of 725 and 595 ft, the upper bracketing value of loss 

in the reach between altitudes of 725 and 595 ft is estimated 

to be about 1.25 Mgal/d (1.94 ft3/s). The average of the 

estimated lower and upper bracketing losses in this reach is 

0.79 Mgal/d (1.22 ft3/s).

Stream Altitudes of 595 to 395 Feet

Measurements to estimate losses between altitudes of 595 

and 395 ft are available for periods when flow was partially 

restored to ‘Īao Stream during December 14, 2006; January 

16–18, 2008; and February 11–15, 2008. Measured losses 

between altitudes of 595 and 395 ft, for upstream flows ranging 

from 14.7 to 29.1 Mgal/d (22.8 to 45.0 ft3

/s), ranged from 0.90 

to 3.2 Mgal/d (1.4 to 5.0 ft3/s) (fig. 34), or about 1.0 to 3.4 

Mgal/d per mile of stream (1.5 to 5.2 ft3/s per mile). Measured 

losses between altitudes of 595 and 395 ft range from about 

4 to 18 percent of the upstream flow at 595 ft. For the flowrestoration period during January 2008, the loss of 3.0 Mgal/d 

(4.6 ft3/s) measured on January 16, 2008, was considered most 

representative for estimating loss in the reach because of the 

timing of the upstream and downstream measurements during 

a period of near-stable discharge. Similarly, for the flowrestoration period during February 2008, the loss of 1.5 Mgal/d 

(2.3 ft3/s) measured on February 13, 2008, was considered most 

representative for estimating loss in the reach. The average 

loss between altitudes of 595 and 395 ft computed from 

measurements on December 14, 2006, January 16, 2008, and 

February 13, 2008, is 2.4 Mgal/d (3.7 ft3/s), or about 2.5 Mgal/d 

per mile of stream (3.8 ft3

/s per mile) (fig. 37A).

Stream Altitudes of 395 to 360 Feet

Measurements are not available to quantify the loss in the 

reach between altitudes of 395 and 360 ft. For the purposes 

of this study, the loss in this reach is estimated by multiplying 

the loss rate (loss per mile of stream length) from the upstream 

reach between altitudes of 595 and 395 ft by the stream distance 

(about 820 ft) between altitudes of 395 and 360 ft. 

Stream Altitudes of 360 to 220 Feet

On the basis of visual observations and measurements 

from September 21, 2004, the reach between altitudes of 

360 and 220 ft gains water. Seepage-run measurements from 

September 21, 2004, indicate a gain of about 0.18 Mgal/d 

Natural, Undiverted Low-Flow Characteristics 63
(0.28 ft3

/s), or about 2.2 percent of the daily mean flow at ‘Īao 

Stream gaging station 16604500 on that day.

A spring on the north side of ‘Īao Stream also contributes 

flow in this reach. The spring discharge is poorly correlated 

with the corresponding daily mean flow at ‘Īao Stream gaging 

station 16604500. The correlation is improved by considering 

the average flow over a period of 8 days (including the current 

day and the 7 previous days) at ‘Īao Stream gaging station 

16604500 (fig. 38). The upper and lower bracketing lines were 

assumed to have the same slope as the regression line. 

Stream Altitudes of 220 to 35 Feet

Measurements to estimate losses between altitudes 

of 220 and 35 ft are available for periods when flow was 

partially restored to ‘Īao Stream during January 18, 2007, and 

February 11–15, 2008. Measured losses between altitudes of 

220 and 35 ft, for upstream flows ranging from 6.14 to 12.0 

Mgal/d (9.50 to 18.5 ft3

/s), ranged from 1.5 to 2.1 Mgal/d (2.3 

to 3.23 ft3/s) (fig. 34), or about 1.1 to 1.6 Mgal/d per mile of 

stream (1.7 to 2.4 ft3/s per mile). Measured losses between 

altitudes of 220 and 35 ft range from about 17 to 33 percent 

of the upstream flow at 220 ft. For the flow-restoration 

period during February 2008, the loss of 2.09 Mgal/d (3.23 

ft3/s) measured on February 14, 2008, was considered most 

representative for estimating loss in the reach because of the 

timing of the upstream and downstream measurements during 

a period of near-stable discharge. The average loss between 

altitudes of 220 and 35 ft computed from measurements on 

January 18, 2007, and February 14, 2008, is 2.1 Mgal/d (3.2 

ft3/s), or about 1.5 Mgal/d per mile of stream (2.3 ft3/s per 

mile). Because the upper bracketing value of loss for this 

reach is nearly equal to the average value, an assumed upper 

bracketing value was set equal to 2.7 Mgal/d (4.1 ft3/s). The 

upper and lower bracketing values of loss are thus equidistant 

from the average value (fig. 37B). 

Waikapu ̄ Stream

Waikapū Stream may flow continuously to Keālia Pond 

during periods of high flow. Full restoration of flow to Waikapū 

Stream during extended dry-weather conditions would establish 

whether Waikapū Stream flows continuously to Keālia Pond for 

natural, undiverted, low-flow conditions. Full restoration of flow 

was not known to have occurred during the period of this study 

and, thus, data representative of diverted conditions and periods 

of recession were used to provide an indication of conditions 

needed to establish flow to Keālia Pond.

Stream Altitudes of 1,160 to 1,080 Feet

Seepage-run measurements between altitudes of 1,160 

and 1,080 ft indicate a gaining reach in Waikapū Stream, after 

accounting for diversion of water by the South Side Ditch 

intake. Measured gains between altitudes of 1,160 and 1,080 

ft, for upstream flows of 1.78 to 2.34 Mgal/d (2.76 to 3.62 

ft3

/s), ranged from 0.12 to 0.19 Mgal/d (0.18 to 0.30 ft3/s), or 

about 0.40 to 0.67 Mgal/d per mile of stream (0.62 to 1.04 ft3/s 

per mile). The average measured gain between altitudes of 

1,160 and 1,080 ft was about 7 percent of the upstream flow, 

with bracketing values of 6 and 9 percent. 

Stream Altitudes of 1,080 to 950 Feet

For stream reaches between altitudes of 1,080 and 950 ft, 

available data from March 3, 2007; November 15, 2007; and 

April 30, 2008, indicate that Waikapū Stream may either gain 

or lose water, which may be reflective of the transition from 

a gaining reach upstream to a losing reach downstream. The 

difference in measured flow between altitudes of 1,080 and 950 

ft ranged from a loss of 0.31 Mgal/d (0.48 ft3/s) to a gain of 

0.078 Mgal/d (0.12 ft3/s). The gain of 0.078 Mgal/d (0.12 ft3/s) 

represents about 4 percent of the flow near an altitude of 1,160 

ft. The average measured difference indicates a loss of about 

0.14 Mgal/d (0.21 ft3/s) (fig. 35).

A tributary that enters the north (left) side of Waikapū 

Stream near an altitude of about 1,050 ft contributes an average 

of about 1.16 Mgal/d (1.80 ft3/s) to the main stream. The 

tributary inflow ranged from about 0.99 to 1.47 Mgal/d (1.53 to 

2.27 ft3/s) and is not strongly correlated to the undiverted flow 

in Waikapū Stream near an altitude of 1,160 ft. 

Stream Altitudes of 950 to 820 Feet

Everett Ditch diverts water from and returns water to 

the stream in this reach. The diffuse return flow from Everett 

Ditch could not be accurately measured, although most of the 

diverted water probably returns to the stream. Seepage-run 

measurements from November 15, 2007, and April 30, 2008, 

can be used to provide an upper estimate of the loss in this 

reach. (Discharge measurements near stream altitudes of 950 

and 820 ft also are available from March 3, 2007; August 

1, 2007; and April 29, 2008, but return flow from the South 

Side Ditch within this reach was not quantified on these 

days.) The measured losses for this reach were 0.02 and 0.09 

Mgal/d (0.025 and 0.14 ft3

/s) on November 15, 2007, and 

April 30, 2008, respectively, and averaged 0.05 Mgal/d (0.08 

ft3/s). The assumed lower bracketing value for the loss in this 

reach is zero, and the upper bracketing value corresponds to 

the greatest measured loss of 0.09 Mgal/d (0.14 ft3/s).

Stream Altitudes of 820 to 560 Feet

Seepage-run measurements between altitudes of 820 

and 560 ft indicate a losing reach. Measured losses between 

altitudes of 820 and 560 ft, for upstream flows of 1.26 to 3.08 

Mgal/d (1.95 to 4.76 ft3/s), ranged from 0.15 to 0.39 Mgal/d 

(0.23 to 0.60 ft3

/s), or about 0.17 to 0.44 Mgal/d per mile of 

64 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
0 2 4 6 8 10 12

0 5 10 15 20 25 30

0 5 10 15 20 25 30 35 40 45 50

0

5

10

15

20

25

30

35

45

40

50

UPSTREAM DISCHARGE NEAR AN ALTITUDE OF 595 FEET, IN CUBIC FEET PER SECOND

DOWNSTREAM DISCHARGE NEAR AN ALTITUDE OF 395 FEET,

IN CUBIC FEET PER SECOND

0 2 4 6 8 10 12 14 16 18 20

0

2

4

6

0

4

2

6

8

10

12

0

10

5

15

20

25

30

8

10

12

18

14

16

20

UPSTREAM DISCHARGE NEAR AN ALTITUDE OF 220 FEET, IN CUBIC FEET PER SECOND

UPSTREAM DISCHARGE NEAR AN ALTITUDE OF 595 FEET, IN MILLION GALLONS PER DAY

UPSTREAM DISCHARGE NEAR AN ALTITUDE OF 220 FEET, IN MILLION GALLONS PER DAY

DOWNSTREAM DISCHARGE NEAR AN ALTITUDE OF 35 FEET,

IN CUBIC FEET PER SECOND

DOWNSTREAM DISCHARGE NEAR AN ALTITUDE OF 395 FEET,

IN MILLION GALLONS PER DAY

DOWNSTREAM DISCHARGE NEAR AN ALTITUDE OF 35 FEET,

IN MILLION GALLONS PER DAY

A

B

UPPER BRACKETING ESTIMATE

RELATION FROM AVAILABLE DATA

LOWER BRACKETING ESTIMATE

DATA USED TO DEFINE RELATION

DATA NOT USED TO DEFINE RELATION

Figure 37. Relation between undiverted streamflows at an upstream and downstream site, ÿĪao Stream, Maui, 

Hawaiÿi. A, Altitudes of 595 and 395 feet. B, Altitudes of 220 and 35 feet.

Natural, Undiverted Low-Flow Characteristics 65
0 5 10 15 20 25 30 35 40 45

0 10 20 30 40 50 60 70

0.0

0.2

0.4

0.6

0.0

0.4

0.2

0.6

0.8

1.0

1.2

0.8

1.0

1.2

1.8

1.4

1.6

2.0

8-DAY AVERGE DISCHARGE AT STREAM-GAGING STATION 16604500, ÿÏAO STREAM,

IN CUBIC FEET PER SECOND

8-DAY AVERGE DISCHARGE AT STREAM-GAGING STATION 16604500, ÿÏAO STREAM,

IN MILLION GALLONS PER DAY

MOKUHAU SPRING DISCHARGE, IN CUBIC FEET PER SECOND

MOKUHAU SPRING DISCHARGE, IN MILLION GALLONS PER DAY

UPPER BRACKETING ESTIMATE

RELATION FROM AVAILABLE DATA

LOWER BRACKETING ESTIMATE

DATA USED TO DEFINE RELATION

Figure 38. Relation between discharge from the Mokuhau Spring and discharge at streamgaging station 16604500, ÿÏao Stream, Maui, Hawaiÿi. Eight-day average discharge for streamgaging station 16604500 computed from current (same day as Mokuhau Spring measurement)

and seven previous days. 

Figure 38. Relation between discharge from the Mokuhau Spring and discharge at stream-gagingstation 

16604500, ÿĪao Stream, Maui, Hawaiÿi. Eight-day average discharge for stream-gaging station 16604500 

computed from current (same day as Mokuhau Spring measurement) and seven previous days.

stream (0.26 to 0.68 ft3/s per mile). The average measured loss 

between altitudes of 820 and 560 ft was about 0.27 Mgal/d (0.42 

ft3/s), or about 0.31 Mgal/d per mile of stream (0.48 ft3/s per 

mile) (fig. 39A). Three measurements of loss were made during 

April 2008, when upstream flows were varied on separate days 

because of ditch-maintenance activities.

Stream Altitudes of 560 to 400 Feet

Seepage-run measurements from October 28, 2004, 

between altitudes of 560 and 460 ft indicate a reach that 

neither gains nor loses appreciable amounts of water. The 

estimated lower bracketing loss and average loss in the reach 

between altitudes of 560 and 400 ft were thus assumed to be 

zero. The upper bracketing loss rate from the upstream reach 

between altitudes of 820 and 560 ft was used to characterize 

the upper bracketing loss in the reach between altitudes of 560 

and 400 ft. The reach between altitudes of 820 and 560 ft more 

closely resembles the reach between altitudes of 560 and 400 

ft, in terms of slope and channel material, than the downstream 

reach between altitudes of 400 and 40 ft. Applying the upper 

bracketing loss rate between altitudes of 820 and 560 ft to 

the reach between altitudes of 560 and 400 ft results in an 

estimated upper bracketing loss of 0.35 Mgal/d (0.54 ft3/s) 

between altitudes of 560 and 400 ft.

Stream Altitudes of 400 to 40 Feet

Downstream of an altitude of 400 ft, only limited data 

are available to evaluate stream loss rates because steady 

flow in the lower reaches of Waikapū Stream was rarely 

observed. In general, loss rates downstream of an altitude 

of 400 ft are higher than loss rates farther upstream, which 

may reflect (1) higher flow conditions associated with the 

measurements downstream of an altitude of 400 ft, (2) more 

permeable sedimentary deposits in and beneath the streambed 

downstream of an altitude of 400 ft relative to farther 

upstream, or (3) reduced channel gradient downstream of an 

altitude of 400 ft. Seepage-run measurements downstream 

of an altitude of 400 ft were made on March 18, 2004, 

during a likely recession period; on August 22, 2006, and 

April 2, 2007, when flows for characterizing loss rates were 

observed; and on January 29 and March 13, 2009, during 

streamflow recessions. The measurements from January 

29 and March 13, 2009, covered the entire reach between 

altitudes of 400 and 40 ft, whereas the measurements on the 

other days covered only partial reaches between altitudes of 

400 and 40 ft. On the basis of available information described 

below, the loss between altitudes of 400 and 40 ft ranged 

from 2.81 to 8.40 Mgal/d (4.34 to 13.0 ft3

/s), corresponding 

to loss rates of 0.78 to 2.3 Mgal/d per mile of stream (1.2 to 

3.6 ft3/s per mile). The average loss in this reach, estimated 

66 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
from the higher of two loss values measured on each day 

(January 29 and March 13, 2009), was 5.9 Mgal/d (9.2 ft3/s), 

corresponding to a loss rate of 1.7 Mgal/d per mile of stream 

(2.6 ft3/s per mile) (fig. 39).

On March 18, 2004, measured flows in Waikapū Stream 

near altitudes of 360 and 40 ft respectively were 10.5 and 4.59 

Mgal/d (16.3 and 7.10 ft3/s). The measured loss rate between 

altitudes of 360 and 40 ft was 1.7 Mgal/d per mile of stream 

(2.6 ft3/s per mile). The measurement near an altitude of 40 

ft was made about an hour before the measurement near an 

altitude of 360 ft. The timing of the measurements during a 

likely recession indicates that the measured loss between 360 

and 40 ft may be low relative to the expected loss for steady 

flow conditions. Applying the measured loss rate between 

altitudes of 360 and 40 ft to the reach between altitudes of 400 

and 40 ft results in an estimated flow of 10.8 Mgal/d (16.7 

ft3/s) at an altitude of 400 ft needed for a flow of 4.59 Mgal/d 

(7.10 ft3/s) near an altitude of 40 ft. 

On August 22, 2006, the measured flow near an altitude 

of 400 ft was 2.60 Mgal/d (4.03 ft3/s), and flow near an 

altitude of about 225 ft was zero, corresponding to a loss rate 

of about 2.3 Mgal/d per mile of stream (3.6 ft3/s per mile). 

Flow near an altitude of 400 ft was visibly higher 14 hours 

before the measurement on August 22, 2006. Applying the 

measured loss rate between altitudes of 400 and 225 ft to the 

reach between altitudes of 400 and 40 ft results in an estimated 

flow of 8.40 Mgal/d (13.0 ft3/s) at an altitude of 400 ft needed 

to initiate flow near an altitude of 40 ft. 

On April 2, 2007, the measured loss between altitudes 

of 400 and 195 ft was 1.14 Mgal/d (1.77 ft3/s), or about 0.78 

Mgal/d per mile of stream (1.2 ft3/s per mile), for an upstream 

flow of 4.78 Mgal/d (7.40 ft3/s); the loss of 1.14 Mgal/d (1.77 

ft3/s) represents 24 percent of the upstream flow in the reach. 

Photographic data indicate that flow at the two sites was 

relatively steady during the period of measurement, although 

flow appeared to have receded over the period from 6 hours to 

1 hour before the measurement period. Applying the measured 

loss rate between altitudes of 400 and 195 ft to the reach 

between altitudes of 400 and 40 ft results in an estimated flow 

of 1.98 Mgal/d (3.06 ft3

/s) near an altitude of 40 ft for a flow 

of 4.78 Mgal/d (7.40 ft3/s) near an altitude of 400 ft. 

On January 29, 2009, and March 13, 2009, discharge 

measurements were made in Waikapū Stream near altitudes 

of 40 ft and 400 ft. Because flow was receding on both days, 

measurements were made, in order, at the downstream site, 

the upstream site, and then again at the downstream site. On 

January 29, 2009, the measured loss between altitudes of 

400 and 40 ft ranged from 4.4 to 7.17 Mgal/d (6.8 to 11.1 

ft3

/s), representing 27 to 44 percent of the upstream flow in 

the reach. On March 13, 2009, the measured loss between 

altitudes of 400 and 40 ft ranged from 3.8 to 4.7 Mgal/d (5.9 

to 7.3 ft3/s), representing 42 to 51 percent of the upstream flow 

in the reach. Because of the distance between the upstream 

and downstream sites and the timing of the measurements, the 

estimated losses from these measurements may be less than 

would be expected during steady flow conditions.

Stream Altitudes of 40 to 20 Feet

On March 18, 2004, measured flows in Waikapū Stream 

near altitudes of 40 and 20 ft were, respectively, 4.59 and 3.71 

Mgal/d (7.10 and 5.74 ft3/s). The measured loss rate between 

altitudes of 40 and 20 ft was 1.5 Mgal/d per mile of stream 

(2.3 ft3/s per mile). The measurement near an altitude of 40 

ft was made about an hour before the measurement near an 

altitude of 20 ft. The timing of the measurements during a 

likely recession indicates that the measured loss between 40 

and 20 ft may be a reasonable estimate of the expected loss for 

steady flow conditions. Applying the average loss rate between 

altitudes of 400 and 40 ft to the reach between altitudes of 40 

and 20 ft results in an estimated loss of 0.92 Mgal/d (1.43 ft3/s) 

between altitudes of 40 and 20 ft. The extrapolated loss of 

0.92 Mgal/d (1.43 ft3/s) is similar to the measured loss of 0.88 

Mgal/d (1.36 ft3/s) for the reach between altitudes of 40 and 

20 ft. Bracketing estimates of the loss between altitudes of 40 

and 20 ft also were estimated by extrapolating the bracketing 

loss rates between altitudes of 400 and 40 ft. The resulting 

bracketing estimates for the loss between altitudes of 40 and 

20 ft ranged from 0.45 to 1.34 Mgal/d (0.69 to 2.08 ft3/s). 

Stream Altitudes of 20 to 10 Feet

Measurements are not available to characterize the loss 

in the reach between altitudes of 20 and 10 ft. For this study, 

the loss for the reach between altitudes of 20 and 10 ft was 

estimated by extrapolation of the loss rate between altitudes of 

400 and 40 ft. The estimated average loss in the reach between 

altitudes of 20 and 10 ft is 1.29 Mgal/d (1.99 ft3/s), ranging from 

0.63 to 1.87 Mgal/d (0.97 to 2.89 ft3/s).

Natural, Undiverted Flow Characteristics at 

Ungaged Sites

Natural, undiverted streamflows at ungaged sites downstream 

of existing diversions can be estimated using information from 

the seepage runs in conjunction with data from the active and 

historical stream-gaging stations. Selected duration discharges 

(Q50, Q55, Q60, Q65, Q70, Q75, Q80, Q85, Q90, Q95, and Q99) were 

estimated at sites downstream of the uppermost diversions on each 

stream. Because of uncertainty in the estimated losses, upper and 

lower bounding estimates also were developed (tables 18–21).

For each stream, duration discharges computed using records 

from an existing gaging station (station 16614000 on Wahie‘e 

River and station 16604500 on ‘Īao Stream) or derived from 

record-extension methods using historical data from previously 

operated gaging stations (station 16608000 on North Waiehu 

Stream; station 16610000 on South Waiehu Stream; and stations 

16648000, 16649000, and 16650000 on Waikapū Stream) were 

used as a starting point for determining duration discharges at 

selected ungaged sites on each stream. Estimated gains or losses 

from seepage-run measurements were used with the duration 

Natural, Undiverted Low-Flow Characteristics 67
0.0

0 2 4 6 8 10 12 14 16 18

0.5 1.0 1.5 2.0 2.5 3.0

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

0.0

0.5

1.0

1.5

2.0

2.5

3.5

3.0

5.0

4.5

4.0

UPSTREAM DISCHARGE NEAR AN ALTITUDE OF 820 FEET, IN CUBIC FEET PER SECOND

DOWNSTREAM DISCHARGE NEAR AN ALTITUDE OF 560 FEET,

IN CUBIC FEET PER SECOND

0 5 10 15 20 25 30

0

5

10

15

0.0

0.5

1.0

1.5

2.0

3.0

2.5

0

2

4

6

8

10

16

14

12

18

20

25

30

UPSTREAM DISCHARGE NEAR AN ALTITUDE OF 400 FEET, IN CUBIC FEET PER SECOND

UPSTREAM DISCHARGE NEAR AN ALTITUDE OF 820 FEET, IN MILLION GALLONS PER DAY

UPSTREAM DISCHARGE NEAR AN ALTITUDE OF 400 FEET, IN MILLION GALLONS PER DAY

DOWNSTREAM DISCHARGE NEAR AN ALTITUDE OF 40 FEET,

IN CUBIC FEET PER SECOND

DOWNSTREAM DISCHARGE NEAR AN ALTITUDE OF 560 FEET,

IN MILLION GALLONS PER DAY

DOWNSTREAM DISCHARGE NEAR AN ALTITUDE OF 40 FEET,

IN MILLION GALLONS PER DAY

A

B

UPPER BRACKETING ESTIMATE

RELATION FROM AVAILABLE DATA

LOWER BRACKETING ESTIMATE

DATA USED TO DEFINE RELATION

DATA NOT USED TO DEFINE RELATION

DATA FROM A SUBREACH, EXTRAPOLATED

 TO ENTIRE REACH

Figure 39. Relation between undiverted streamflows at an upstream and downstream site, Waikapü Stream, 

Maui, Hawaiÿi. A, Altitudes of 820 and 560 feet. B, Altitudes of 400 and 40 feet.

68 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Table 18. Selected duration discharges (natural, undiverted conditions) for Waiheÿe River during 

climate years 1984–2007, Maui, Hawaiÿi.

[Mgal/d, million gallons per day; ft, feet; values in light grey text are lower and upper bracketing values]

Flow-duration 

percentile

Duration discharges for selected altitudes of Waiheÿe River, in Mgal/d

(values in parentheses are in cubic feet per second)

605 ft1 400 ft 310 ft 270 ft 100 ft 45 ft

50

55

60

65

70

75

80

85

90

95

99

1

From record of gaging station 16614000.

202

Table 18. Selected duration discharges (natural, undiverted conditions) for Waiheÿe River 

during climate years 1984–2007, Maui, Hawai‘i. 

[Mgal/d, million gallons per day; values in light grey text are lower and upper bracketing values] 

 Duration discharges for selected altitudes of Waiheÿe River, in Mgal/d 

(values in parentheses are in cubic feet per second) 

Flowduration 

percentile 

605 ft1

 400 ft 310 ft 270 ft 100 ft 45 ft 

50 34 (52) 

34 (52) 

34 (53) 

35 (54) 

34 (52) 

34 (53) 

35 (54) 

33 (51) 

34 (52) 

34 (53) 

31 (48) 

33 (51) 

34 (53) 

30 (47) 

32 (50) 

34 (53) 

55 32 (50) 

32 (50) 

33 (51) 

34 (52) 

32 (50) 

33 (51) 

34 (52) 

32 (49) 

32 (50) 

33 (51) 

30 (46) 

32 (49) 

33 (51) 

29 (45) 

31 (48) 

33 (51) 

60 31 (48) 

31 (48) 

32 (49) 

32 (50) 

31 (48) 

32 (49) 

32 (50) 

30 (47) 

31 (48) 

32 (49) 

28 (44) 

30 (47) 

32 (49) 

28 (43) 

30 (46) 

32 (49) 

65 30 (46) 

30 (46) 

30 (47) 

31 (48) 

30 (46) 

30 (47) 

31 (48) 

29 (45) 

30 (46) 

30 (47) 

27 (42) 

29 (45) 

30 (47) 

27 (41) 

28 (44) 

30 (47) 

70 28 (44) 

28 (44) 

29 (45) 

30 (46) 

28 (44) 

29 (45) 

30 (46) 

28 (43) 

28 (44) 

29 (45) 

26 (40) 

28 (43) 

29 (45) 

25 (39) 

27 (42) 

29 (45) 

75 28 (43) 

28 (43) 

28 (44) 

29 (45) 

28 (43) 

28 (44) 

29 (45) 

27 (42) 

28 (43) 

28 (44) 

25 (39) 

27 (42) 

28 (44) 

25 (38) 

27 (41) 

28 (44) 

80 27 (41) 

27 (41) 

27 (42) 

28 (43) 

27 (41) 

27 (42) 

28 (43) 

26 (40) 

27 (41) 

27 (42) 

24 (37) 

26 (40) 

27 (42) 

23 (36) 

25 (39) 

27 (42) 

85 25 (39) 

25 (39) 

26 (40) 

27 (41) 

25 (39) 

26 (40) 

27 (41) 

25 (38) 

25 (39) 

26 (40) 

23 (35) 

25 (38) 

26 (40) 

22 (34) 

24 (37) 

26 (40) 

90 24 (37) 

24 (37) 

25 (38) 

25 (39) 

24 (37) 

25 (38) 

25 (39) 

23 (36) 

24 (37) 

25 (38) 

21 (33) 

23 (36) 

25 (38) 

21 (32) 

23 (35) 

25 (38) 

95 22 (34) 

22 (34) 

23 (35) 

23 (36) 

22 (34) 

23 (35) 

23 (36) 

21 (33) 

22 (34) 

23 (35) 

19 (30) 

21 (33) 

23 (35) 

19 (29) 

21 (32) 

23 (35) 

99 18 (28) 

18 (28) 

19 (29) 

19 (30) 

18 (28) 

19 (29) 

19 (30) 

17 (27) 

18 (28) 

19 (29) 

16 (24) 

17 (27) 

19 (29) 

15 (23) 

17 (26) 

19 (29) 

1

From record of gaging station 16614000. 

Natural, Undiverted Low-Flow Characteristics 69
70 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄

Table 19. Selected duration discharges (natural, undiverted conditions) for Waiehu Stream during climate years 1984–2007, Maui, 

Hawaiÿi.

[Mgal/d, million gallons per day; ft, feet; values in light grey text are lower and upper bracketing values]

Flow-duration 

percentile

Duration discharges for selected altitudes of Waiehu Stream, in Mgal/d

(values in parentheses are in cubic feet per second)

North Waiehu Stream South Waiehu Stream Waiehu Stream

880 ft1 475 ft 280 ft 870 ft2 280 ft 190 ft 20 ft

50 

55

60

65

70

75

80

85

90

95

99

1

From extension of record of gaging station 16608000 (based on average value, excluding ÿÏao Stream index stations). Discharge assumed to be equal to discharge at an altitude of 

920 feet. 2

From extension of record of gaging station 16610000 (based on average value, excluding ÿÏao Stream index stations).

PROVISIONAL DRAFT—Do not quote or release 

203

Table 19. Selected duration discharges (natural, undiverted conditions) for Waiehu Stream 

during climate years 1984–2007, Maui, Hawai‘i. 

[Mgal/d, million gallons per day; values in light grey text are lower and upper bracketing values] 

Duration discharges for selected altitudes of Waiehu Stream, in Mgal/d 

(values in parentheses are in cubic feet per second) 

North Waiehu Stream South Waiehu Stream Waiehu Stream 

Flow-duration 

percentile 880 ft1

 475 ft 280 ft 870 ft2 280 ft 190 ft 20 ft 

50 3.2 (4.9) 

1.7 (2.6) 

1.9 (2.9) 

2.1 (3.2) 

1.1 (1.7) 

1.5 (2.3) 

1.7 (2.6) 

 3.2 (5.0) 

1.3 (2.0) 

2.3 (3.5) 

3.2 (5.0) 

2.3 (3.6) 

3.9 (6.1) 

5.6 (8.7) 

1.7 (2.7) 

3.2 (4.9) 

4.7 (7.3) 

55 3.0 (4.6) 

1.5 (2.3) 

1.7 (2.7) 

1.9 (2.9) 

0.90 (1.4) 

1.4 (2.1) 

1.6 (2.4) 

 3.0 (4.7) 

1.1 (1.7) 

2.1 (3.2) 

3.0 (4.7) 

2.0 (3.1) 

3.6 (5.5) 

5.3 (8.2) 

1.4 (2.2) 

2.8 (4.4) 

4.4 (6.8) 

60 2.8 (4.3) 

1.4 (2.1) 

1.6 (2.5) 

1.7 (2.7) 

0.78 (1.2) 

1.2 (1.8) 

1.4 (2.1) 

 2.7 (4.2) 

0.78 (1.2) 

1.7 (2.7) 

2.7 (4.2) 

1.6 (2.4) 

3.1 (4.8) 

4.8 (7.4) 

1.0 (1.6) 

2.5 (3.8) 

3.9 (6.1) 

65 2.7 (4.1) 

1.3 (2.0) 

1.5 (2.3) 

1.6 (2.5) 

0.71 (1.1) 

1.1 (1.7) 

1.3 (2.0) 

 2.5 (3.8) 

0.49 (0.76) 

1.5 (2.3) 

2.5 (3.8) 

1.2 (1.8) 

2.7 (4.2) 

4.4 (6.8) 

0.71 (1.1) 

2.1 (3.3) 

3.6 (5.6) 

70 2.5 (3.8) 

1.1 (1.7) 

1.4 (2.1) 

1.5 (2.3) 

0.53 (0.82) 

0.97 (1.5) 

1.2 (1.8) 

 2.3 (3.5) 

0.30 (0.46) 

1.3 (2.0) 

2.3 (3.5) 

0.84 (1.3) 

2.4 (3.7) 

4.1 (6.3) 

0.41 (0.63) 

1.8 (2.8) 

3.3 (5.1) 

75 2.3 (3.5) 

0.97 (1.5) 

1.2 (1.8) 

1.4 (2.1) 

0.38 (0.59) 

0.78 (1.2) 

0.97 (1.5) 

 2.1 (3.2) 

0.10 (0.16) 

1.1 (1.7) 

2.1 (3.2) 

0.48 (0.75) 

2.0 (3.1) 

3.7 (5.7) 

0.11 (0.17) 

1.5 (2.3) 

3.0 (4.6) 

80 2.1 (3.2) 

0.84 (1.3) 

1.0 (1.6) 

1.2 (1.8) 

0.23 (0.36) 

0.65 (1.0) 

0.84 (1.3) 

 1.8 (2.8) 

0 

0.84 (1.3) 

1.8 (2.8) 

0.23 (0.36) 

1.6 (2.5) 

3.2 (5.0) 

0 

1.1 (1.8) 

2.6 (4.0) 

85 1.9 (3.0) 

0.71 (1.1) 

0.97 (1.5) 

1.1 (1.7) 

0.13 (0.20) 

0.54 (0.84) 

0.71 (1.1) 

 1.6 (2.5) 

0 

0.63 (0.98) 

1.6 (2.5) 

0.13 (0.20) 

1.3 (2.0) 

3.0 (4.6) 

0 

0.90 (1.4) 

2.3 (3.6) 

90 1.7 (2.6) 

0.52 (0.80) 

0.71 (1.1) 

0.90 (1.4) 

0 

0.34 (0.53) 

0.54 (0.83) 

 1.4 (2.2) 

0 

0.44 (0.68) 

1.4 (2.2) 

0 

0.90 (1.4) 

2.5 (3.9) 

0 

0.52 (0.81) 

1.9 (3.0) 

95 1.5 (2.3) 

0.37 (0.57) 

0.59 (0.91) 

0.78 (1.2) 

0 

0.19 (0.30) 

0.39 (0.60) 

 1.2 (1.9) 

0 

0.25 (0.38) 

1.2 (1.9) 

0 

0.53 (0.82) 

2.1 (3.3) 

0 

0.21 (0.33) 

1.7 (2.6) 

99 0.97 (1.5) 

0 

0.19 (0.30) 

0.35 (0.54) 

0 

0 

0 

 0.84 (1.3) 

0 

0 

0.84 (1.3) 

0 

0.058 (0.090) 

1.3 (2.0) 

0 

0 

0.90 (1.4) 

1

From extension of record of gaging station 16608000 (based on average value, excluding ÿÏao Stream index stations). 

Discharge assumed to be equal to discharge at an altitude of 920 feet. 

2

From extension of record of gaging station 16610000 (based on average value, excluding ÿÏao Stream index stations). 
Natural, Undiverted Low-Flow Characteristics 71

Table 20. Selected duration discharges (natural, undiverted conditions) for ÿI

−

ao Stream during climate years 

1984–2007, Maui, Hawaiÿi.

[Mgal/d, million gallons per day; ft, feet; values in light grey text are lower and upper bracketing values]

Flow-duration 

percentile

Duration discharges for selected altitudes of ÿI

−

ao Stream, in Mgal/d

(values in parentheses are in cubic feet per second)

780 ft1 725 ft 595 ft 395 ft 260 ft 220 ft 35 ft

50 

55

60

65

70

75

80

85

90

95

99

1

From record of gaging station 16604500.

PROVISIONAL DRAFT—Do not quote or release 

204

Table 20. Selected duration discharges (natural, undiverted conditions) for ÿÏao Stream 

during climate years 1984–2007, Maui, Hawai‘i. 

[Mgal/d, million gallons per day; values in light grey text are lower and upper bracketing values] 

Duration discharges for selected altitudes of ÿÏao Stream, in Mgal/d 

(values in parentheses are in cubic feet per second) 

Flowduration 

percentile 

780 ft1

 725 ft 595 ft 395 ft 260 ft 220 ft 35 ft 

50 25 (39) 

26 (40) 

26 (40) 

26 (40) 

25 (38) 

25 (39) 

26 (40) 

21 (33) 

23 (35) 

25 (38) 

21 (33) 

23 (36) 

26 (40) 

21 (33) 

23 (36) 

26 (40) 

19 (29) 

21 (33) 

25 (38) 

55 23 (35) 

23 (35) 

23 (36) 

23 (36) 

22 (34) 

22 (34) 

23 (35) 

19 (29) 

20 (31) 

22 (34) 

19 (29) 

21 (32) 

23 (36) 

19 (29) 

21 (32) 

23 (36) 

16 (25) 

19 (29) 

21 (33) 

60 21 (32) 

21 (32) 

21 (33) 

21 (33) 

19 (30) 

20 (31) 

21 (32) 

16 (25) 

18 (28) 

20 (31) 

17 (26) 

19 (29) 

21 (32) 

17 (26) 

19 (29) 

21 (32) 

14 (22) 

16 (25) 

19 (30) 

65 19 (30) 

19 (30) 

20 (31) 

20 (31) 

18 (28) 

19 (29) 

19 (30) 

15 (23) 

17 (26) 

19 (29) 

16 (24) 

17 (27) 

19 (30) 

16 (24) 

17 (27) 

19 (30) 

13 (20) 

15 (23) 

18 (28) 

70 17 (27) 

17 (27) 

18 (28) 

18 (28) 

16 (25) 

17 (26) 

17 (27) 

13 (20) 

15 (23) 

17 (26) 

14 (21) 

15 (23) 

17 (27) 

14 (21) 

15 (23) 

17 (27) 

11 (17) 

13 (20) 

16 (25) 

75 16 (25) 

16 (25) 

17 (26) 

17 (26) 

15 (23) 

16 (24) 

16 (25) 

12 (18) 

14 (21) 

16 (24) 

12 (19) 

14 (21) 

16 (25) 

12 (19) 

14 (21) 

16 (25) 

9.7 (15) 

12 (18) 

15 (23) 

80 15 (23) 

15 (23) 

15 (23) 

16 (24) 

14 (21) 

14 (22) 

15 (23) 

10 (16) 

12 (19) 

14 (22) 

10 (16) 

12 (19) 

15 (23) 

10 (16) 

12 (19) 

15 (23) 

7.8 (12) 

10 (16) 

13 (20) 

85 14 (21) 

14 (21) 

14 (21) 

14 (22) 

12 (19) 

13 (20) 

14 (21) 

9.0 (14) 

11 (17) 

13 (20) 

9.0 (14) 

11 (17) 

14 (21) 

9.0 (14) 

11 (17) 

14 (21) 

6.5 (10) 

9.0 (14) 

12 (18) 

90 12 (19) 

12 (19) 

12 (19) 

13 (20) 

11 (17) 

12 (18) 

12 (19) 

7.8 (12) 

9.0 (14) 

12 (18) 

7.8 (12) 

9.7 (15) 

12 (19) 

7.8 (12) 

9.7 (15) 

12 (19) 

5.2 (8.1) 

7.8 (12) 

10 (16) 

95 11 (17) 

11 (17) 

11 (17) 

12 (18) 

9.7 (15) 

10 (16) 

11 (17) 

6.5 (10) 

7.8 (12) 

10 (16) 

6.5 (10) 

8.4 (13) 

10 (16) 

6.5 (10) 

8.4 (13) 

10 (16) 

3.9 (6.0) 

6.1 (9.5) 

9.0 (14) 

99 8.4 (13) 

8.4 (13) 

8.4 (13) 

8.4 (13) 

7.1 (11) 

7.8 (12) 

8.4 (13) 

4.1 (6.3) 

5.4 (8.4) 

7.8 (12) 

3.8 (5.9) 

5.4 (8.4) 

7.8 (12) 

3.8 (5.9) 

5.4 (8.4) 

7.8 (12) 

1.2 (1.8) 

3.4 (5.2) 

6.3 (9.8) 

1

From record of gaging station 16604500. 
Table 21. Selected duration discharges (natural, undiverted conditions) for Waikapu− Stream during climate years 1984–2007, 

Maui, Hawaiÿi.

[Mgal/d, million gallons per day; ft, feet; values in light grey text are lower and upper bracketing values]

Flow-duration 

percentile

Duration discharges for selected altitudes of Waikapu

− Stream, in Mgal/d

(values in parentheses are in cubic feet per second)

1,160 ft 1,080 ft 950 ft 820 ft 560 ft 400 ft 40 ft 10 ft

50 

55

60

65

70

75

80

85

90

95

99

205

Table 21. Selected duration discharges (natural, undiverted conditions) for Waikapü Stream 

during climate years 1984–2007, Maui, Hawai‘i. 

[Mgal/d, million gallons per day; values in light grey text are lower and upper bracketing values] 

Duration discharges for selected altitudes of Waikapü Stream, in Mgal/d 

(values in parentheses are in cubic feet per second) 

Flowduration 

percentile 

1,160 ft 1,080 ft 950 ft 820 ft 560 ft 400 ft 40 ft 10 ft 

50 

3.6 (5.6) 

4.3 (6.6) 

4.7 (7.2) 

4.5 (7.0) 

4.6 (7.1) 

4.7 (7.2) 

5.2 (8.0) 

5.6 (8.7) 

6.3 (9.7) 

5.1 (7.9) 

5.6 (8.6) 

6.3 (9.7) 

4.7 (7.3) 

5.3 (8.2) 

6.1 (9.5) 

4.4 (6.8) 

5.3 (8.2) 

6.1 (9.5) 

0 

0 

3.4 (5.2) 

0 

0 

2.3 (3.5) 

55 

3.4 (5.2) 

4.0 (6.2) 

4.4 (6.8) 

4.3 (6.6) 

4.3 (6.6) 

4.4 (6.8) 

4.9 (7.6) 

5.3 (8.2) 

6.0 (9.3) 

4.8 (7.5) 

5.2 (8.1) 

6.0 (9.3) 

4.5 (6.9) 

5.0 (7.7) 

5.8 (9.0) 

4.1 (6.3) 

5.0 (7.7) 

5.8 (9.0) 

0 

0 

3.0 (4.7) 

0 

0 

1.9 (3.0) 

60 

3.1 (4.8) 

3.7 (5.7) 

4.1 (6.3) 

3.9 (6.0) 

3.9 (6.1) 

4.0 (6.2) 

4.6 (7.1) 

5.0 (7.7) 

5.6 (8.7) 

4.5 (7.0) 

4.9 (7.6) 

5.6 (8.7) 

4.1 (6.4) 

4.7 (7.2) 

5.5 (8.5) 

3.7 (5.8) 

4.7 (7.2) 

5.5 (8.5) 

0 

0 

2.7 (4.1) 

0 

0 

1.6 (2.5) 

65 

2.9 (4.5) 

3.5 (5.4) 

3.9 (6.0) 

3.7 (5.7) 

3.7 (5.8) 

3.8 (5.9) 

4.4 (6.8) 

4.8 (7.4) 

5.4 (8.4) 

4.3 (6.6) 

4.7 (7.3) 

5.4 (8.4) 

3.9 (6.0) 

4.5 (6.9) 

5.2 (8.1) 

3.6 (5.5) 

4.5 (6.9) 

5.2 (8.1) 

0 

0 

2.5 (3.8) 

0 

0 

1.4 (2.1) 

70 

2.7 (4.2) 

3.3 (5.1) 

3.7 (5.7) 

3.5 (5.4) 

3.6 (5.5) 

3.6 (5.6) 

4.2 (6.5) 

4.5 (7.0) 

5.2 (8.0) 

4.1 (6.3) 

4.5 (7.0) 

5.2 (8.0) 

3.7 (5.7) 

4.2 (6.5) 

5.0 (7.8) 

3.4 (5.2) 

4.2 (6.5) 

5.0 (7.8) 

0 

0 

2.3 (3.5) 

0 

0 

1.2 (1.8) 

75 

2.5 (3.9) 

3.1 (4.8) 

3.5 (5.4) 

3.3 (5.1) 

3.3 (5.1) 

3.4 (5.2) 

3.9 (6.1) 

4.3 (6.7) 

5.0 (7.7) 

3.9 (6.0) 

4.3 (6.6) 

5.0 (7.7) 

3.5 (5.4) 

4.0 (6.2) 

4.8 (7.5) 

3.2 (4.9) 

4.0 (6.2) 

4.8 (7.5) 

0 

0 

2.0 (3.1) 

0 

0 

0.97 (1.5) 

80 

2.3 (3.6) 

2.8 (4.4) 

3.2 (5.0) 

3.0 (4.7) 

3.0 (4.7) 

3.1 (4.8) 

3.7 (5.7) 

4.1 (6.3) 

4.7 (7.2) 

3.6 (5.6) 

4.0 (6.2) 

4.7 (7.2) 

3.2 (5.0) 

3.7 (5.8) 

4.5 (7.0) 

2.8 (4.4) 

3.7 (5.8) 

4.5 (7.0) 

0 

0 

1.7 (2.7) 

0 

0 

0.65 (1.0) 

85 

2.1 (3.3) 

2.7 (4.2) 

3.0 (4.7) 

2.9 (4.5) 

2.9 (4.5) 

3.0 (4.6) 

3.6 (5.5) 

3.9 (6.1) 

4.5 (7.0) 

3.5 (5.4) 

3.9 (6.0) 

4.5 (7.0) 

3.1 (4.8) 

3.6 (5.6) 

4.4 (6.8) 

2.7 (4.2) 

3.6 (5.6) 

4.4 (6.8) 

0 

0 

1.6 (2.4) 

0 

0 

0.51 (0.79) 

90 

1.9 (2.9) 

2.5 (3.8) 

2.8 (4.4) 

2.6 (4.0) 

2.7 (4.1) 

2.7 (4.1) 

3.3 (5.1) 

3.7 (5.7) 

4.3 (6.6) 

3.2 (4.9) 

3.6 (5.6) 

4.3 (6.6) 

2.8 (4.3) 

3.4 (5.2) 

4.1 (6.3) 

2.5 (3.8) 

3.4 (5.2) 

4.1 (6.3) 

0 

0 

1.3 (2.0) 

0 

0 

0.22 (0.34) 

95 

1.6 (2.5) 

2.1 (3.3) 

2.5 (3.9) 

2.3 (3.5) 

2.3 (3.5) 

2.3 (3.6) 

2.9 (4.5) 

3.3 (5.1) 

3.9 (6.0) 

2.8 (4.4) 

3.2 (5.0) 

3.9 (6.0) 

2.5 (3.8) 

3.0 (4.6) 

3.7 (5.8) 

2.1 (3.3) 

3.0 (4.6) 

3.7 (5.8) 

0 

0 

0.90 (1.4) 

0 

0 

0 

99 

1.0 (1.6) 

1.6 (2.4) 

1.9 (2.9) 

1.6 (2.5) 

1.7 (2.6) 

1.7 (2.6) 

2.3 (3.6) 

2.7 (4.2) 

3.2 (5.0) 

2.3 (3.5) 

2.7 (4.1) 

3.2 (5.0) 

1.9 (2.9) 

2.4 (3.7) 

3.1 (4.8) 

1.5 (2.3) 

2.4 (3.7) 

3.1 (4.8) 

0 

0 

0.27 (0.41) 

0 

0 

0 

72 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
discharges from gaged sites to determine duration discharges 

at ungaged sites. The method to estimate duration discharges at 

ungaged sites is described in detail below for Waihe‘e River. 

Waiheÿe River

For Waihe‘e River at gaging station 16614000 near an 

altitude of 605 ft, the median (Q50) discharge during climate 

years 1984–2007 was 34 Mgal/d (52 ft3/s); the Q70 discharge 

was 28 Mgal/d (44 ft3/s); and the Q90 discharge was 24 Mgal/d 

(37 ft3/s) (tables 12, 18). The duration discharges for Waihe‘e 

River near an altitude of 605 ft were adjusted by estimated 

gains or losses in downstream reaches to determine the 

duration discharges at ungaged, downstream sites. Data are 

not available to define gains or losses in the reach between 

altitudes of 605 and 585 ft. Thus, duration discharges near an 

altitude of 605 ft are assumed to be representative of duration 

discharges near an altitude of 585 ft. 

In the reach between altitudes of 585 and 400 ft, 

Waihe‘e River gains an average of about 0.39 Mgal/d (0.61 

ft3/s). In addition, Huluhulupueo Stream on the north side 

and two small tributaries on the south side of Waihe‘e River 

contribute about 0.30 Mgal/d (0.47 ft3/s) in the reach between 

altitudes of 585 and 400 ft. Thus, duration discharges for 

Waihe‘e River near an altitude of 400 ft reflect an increase 

of about 0.70 Mgal/d (1.08 ft3/s) relative to the duration 

discharges near an altitude of 605 ft. (For this gaining reach, 

the increase was assumed to be constant and unaffected 

by upstream flow rate. For other gaining reaches, the gain 

generally was assumed to be a percentage of the upstream, 

natural discharge.) Near an altitude of 400 ft, the estimated 

undiverted Q50, Q70, and Q90 discharges were, respectively, 

34, 29, and 25 Mgal/d (53, 45, and 38 ft3/s) (table 18). The 

upper and lower bracketing estimates of duration discharges 

near an altitude of 400 ft account for increases of 1.31 and 

0.19 Mgal/d (2.03 and 0.30 ft3

/s), respectively, relative to the 

duration discharges near an altitude of 605 ft. 

In the reach between altitudes of 400 and 310 ft, 

Waihe‘e River loses an average of about 0.33 Mgal/d (0.51 

ft3

/s), and the duration discharges near an altitude of 310 

ft are less than the duration discharges near an altitude of 

400 ft by this constant amount. Near an altitude of 310 

ft, the estimated undiverted Q50, Q70, and Q90 discharges 

were, respectively, 34, 29, and 25 Mgal/d (53, 45, and 38 

ft3/s) (table 18). The upper and lower bracketing estimates 

of duration discharges near an altitude of 310 ft account 

for losses of 0.19 and 0.47 Mgal/d (0.30 and 0.72 ft3/s), 

respectively, relative to the duration discharges near an 

altitude of 400 ft. 

In the reach between altitudes of 310 and 270 ft, 

Waihe‘e River loses an average of about 0.36 Mgal/d (0.56 

ft3/s), and the duration discharges near an altitude of 270 

ft are less than the duration discharges near an altitude of 

310 ft by this constant amount. Near an altitude of 270 

ft, the estimated undiverted Q50, Q70, and Q90 discharges 

were, respectively, 34, 28, and 24 Mgal/d (52, 44, and 37 

ft3/s) (table 18). The upper and lower bracketing estimates 

of duration discharges near an altitude of 270 ft account 

for losses of 0.28 and 0.45 Mgal/d (0.43 and 0.70 ft3/s), 

respectively, relative to the duration discharges near an 

altitude of 310 ft.

In the reach between altitudes of 270 and 100 ft, 

Waihe‘e River loses an average of about 0.80 Mgal/d (1.25 

ft3/s), and the duration discharges near an altitude of 100 

ft are less than the duration discharges near an altitude of 

270 ft by this constant amount. Near an altitude of 100 

ft, the estimated undiverted Q50, Q70, and Q90 discharges 

were, respectively, 33, 28, and 23 Mgal/d (51, 43, and 36 

ft3/s) (table 18). The upper and lower bracketing estimates 

of duration discharges near an altitude of 100 ft account 

for losses of 0.28 and 1.58 Mgal/d (0.43 and 2.44 ft3

/s), 

respectively, relative to the duration discharges near an 

altitude of 270 ft.

In the reach between altitudes of 100 and 45 ft, Waihe‘e 

River loses an average of about 0.23 Mgal/d (0.35 ft3

/s), 

and the duration discharges near an altitude of 45 ft are less 

than the duration discharges near an altitude of 100 ft by 

this constant amount. Near an altitude of 45 ft, the estimated 

undiverted Q50, Q70, and Q90 discharges were, respectively, 

32, 27, and 23 Mgal/d (50, 42, and 35 ft3/s) (table 18). 

The upper and lower bracketing estimates of duration 

discharges near an altitude of 45 ft account for a gain of 

0.065 Mgal/d (0.10 ft3/s) and a loss of 0.71 Mgal/d (1.10 

ft3/s), respectively, relative to the duration discharges near an 

altitude of 100 ft. 

Waiehu Stream

To estimate the flow-duration discharges in Waiehu Stream, 

the flow-duration discharges at common duration percentiles 

were assumed to occur concurrently in North and South Waiehu 

Streams near altitudes of 880 (station 16608000) and 870 ft 

(station 16610000), respectively. For North Waiehu Stream at 

gaging station 16608000 near an altitude of 880 ft, the estimated 

median discharge during climate years 1984–2007 was 3.2 

Mgal/d (4.9 ft3/s); the estimated Q70 discharge was 2.5 Mgal/d 

(3.8 ft3/s); and the estimated Q90 discharge was 1.7 Mgal/d (2.6 

ft3

/s) (table 15). (The average values from the record extension 

analysis, excluding values resulting from using ‘Īao Stream as 

an index station, were assumed to be the most representative for 

all subsequent analyses.) For South Waiehu Stream at gaging 

station 16610000 near an altitude of 870 ft, the estimated median 

discharge during climate years 1984–2007 was 3.2 Mgal/d (5.0 

ft3/s); the estimated Q70 discharge was 2.3 Mgal/d (3.5 ft3/s); 

and the estimated Q90 discharge was 1.4 Mgal/d (2.2 ft3/s) (table 

16). Downstream of the confluence of North and South Waiehu 

Streams, near an altitude of 20 ft, the estimated undiverted 

Natural, Undiverted Low-Flow Characteristics 73
Q50, Q70, and Q90 discharges were, respectively, 3.2, 1.8, and 

0.52Mgal/d (4.9, 2.8, and 0.81 ft3/s) (table 19).

ÿĪao Stream

For ‘Īao Stream at gaging station 16604500 near an 

altitude of 780 ft, the estimated median discharge during climate 

years 1984–2007 was 25 Mgal/d (39 ft3/s); the estimated Q70

discharge was 17 Mgal/d (27 ft3/s); and the estimated Q90

discharge was 12 Mgal/d (19 ft3/s) (tables 13, 20). Farther 

downstream, near an altitude of 35 ft, the estimated undiverted 

Q50, Q70, and Q90 discharges were, respectively, 21, 13, and 7.8 

Mgal/d (33, 20, and 12 ft3

/s) (table 20).

Waikapu ̄ Stream

For Waikapū Stream near an altitude of 880 ft, the 

estimated median discharge (Q50) during climate years 

1984–2007 was 5.6 Mgal/d (8.6 ft3/s); the estimated Q70

discharge was 4.5 Mgal/d (7.0 ft3

/s); and the estimated Q90

discharge was 3.6 Mgal/d (5.6 ft3/s) (table 17). Upstream, near 

an altitude of 1,160 ft, the estimated undiverted Q50, Q70, and 

Q90 discharges were, respectively, 4.3, 3.3, and 2.5 Mgal/d (6.6, 

5.1, and 3.8 ft3/s) (table 21). Downstream of an altitude of 40 ft, 

the estimated undiverted Q50, Q70, and Q90 discharges were zero 

(table 21). Thus, on the basis of this analysis, Waikapū Stream 

would not have flowed continuously to the coast during climate 

years 1984–2007 in the absence of diversions (or additions) 

of water. Creed (1993, p. 10) indicated that Waikapū Stream 

“flows continuously to the sea, above ground in the valley, and 

underground in portions of the isthmus * * *,” and this statement 

seems to be consistent with results from this study. However, 

Sterling (1998, p. 63) indicated that Waikapū Stream may be 

the only constantly flowing stream near Mā‘alaea. Maciolek 

(1971) also indicated that Waikapū Stream flowed continuously 

throughout its course in a natural state. Neither Sterling (1998) 

nor Maciolek (1971) provide supporting information for their 

statements regarding flow in Waikapū Stream. 

Maintaining Continuous Flows to the Ocean

Maintaining continuous surface flows from the mountains 

to the ocean (mauka to makai) in the Nā Wai ‘Ehā area may be 

important for upstream migration of native stream fauna. To 

estimate the minimum flow necessary to maintain continuous 

mauka to makai flow in each stream, gains and losses 

determined from the seepage-run measurements were used to 

develop relations between the flow upstream of all diversions 

and the downstream flow near the coast (figs. 40–43). These 

relations were developed for natural, undiverted conditions 

(tables 18–21). Because of uncertainty in the estimated losses, 

upper and lower bounding relations also were developed (figs. 

40–43) using the upper and lower bracketing flow estimates 

at the upstream and downstream sites (tables 18–21). The 

upper and lower bounding relations for Waikapū Stream (fig. 

43) indicate greatest uncertainty mainly because seepagerun measurements to constrain losses in the lower reaches 

(downstream of an altitude of 400 ft) were collected during 

periods of recession. Estimates of losses in the lower reaches of 

Waikapū Stream can be improved by restoring all flow to the 

stream for a period sufficient to attain steady flow conditions. 

Waiheÿe River

For Waihe‘e River, a minimum flow of about 1 Mgal/d 

(1.6 ft3/s) near an altitude of 605 ft, corresponding to 

minimum flows of about 1.7 Mgal/d (2.7 ft3/s) near an altitude 

of 400 ft and 1 Mgal/d (1.6 ft3/s) near an altitude of 270 ft, is 

needed to initiate flow near the coast at an altitude of 45 ft, 

assuming no diversions exist in Waihe‘e River downstream of 

an altitude of 605 ft or in any tributaries to Waihe‘e River (fig. 

40). The minimum flow estimate of 1 Mgal/d (1.6 ft3/s) for 

Waihe‘e River near an altitude of 605 ft is much less than the 

minimum recorded flow of 14 Mgal/d (22 ft3/s) during climate 

years 1984–2007 near an altitude of 605 ft. Thus, during 

climate years 1984–2007, Waihe‘e River would have flowed 

continuously to the coast at all times if no diversions existed. 

Waiehu Stream

To estimate the flows in Waiehu Stream near the coast, 

the flow-duration discharges at common duration percentiles 

were assumed to occur concurrently in North and South Waiehu 

Streams. With this approximation, the flow in Waiehu Stream, 

downstream of the confluence of North and South Waiehu 

Streams, could be estimated (fig. 41). For Waiehu Stream, a 

minimum flow of 1.3 Mgal/d (2.1 ft3

/s) near an altitude of 880 

ft in North Waiehu Stream, corresponding to a flow of about 1.1 

Mgal/d (1.7 ft3/s) in South Waiehu Stream near an altitude of 870 

ft, is needed to initiate flow near the coast at an altitude of 20 ft, 

assuming no diversions exist downstream of an altitude of 880 

ft in North Waiehu Stream and 870 ft in South Waiehu Stream 

(fig. 41). (For the purposes of this study, the flows at altitudes of 

920 and 880 ft in North Waiehu Stream are considered equal.) 

The minimum flow estimate of 1.3 Mgal/d (2.1 ft3/s) for North 

Waiehu Stream near an altitude of 880 ft is between the estimated 

Q95 and Q99 flows during climate years 1984–2007. Thus, during 

climate years 1984–2007, Waiehu Stream would have flowed 

continuously to the coast at least 95 percent of the time if no 

diversions existed. The minimum flows near altitudes of 880 ft in 

North Waiehu Stream and 870 ft in South Waiehu Stream needed 

to initiate flow near the coast at an altitude of 20 ft correspond to 

minimum flows of about 0.1 Mgal/d (0.2 ft3

/s) near an altitude of 

280 ft in South Waiehu Stream and 0.3 Mgal/d (0.4 ft3/s) near an 

altitude of 190 ft in Waiehu Stream.

74 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
0 10 20 30 40 50 60

0

10

20

30

40

50

60

UPSTREAM DISCHARGE NEAR AN ALTITUDE OF 605 FEET, IN CUBIC FEET PER SECOND

DOWNSTREAM DISCHARGE NEAR AN ALTITUDE OF 45 FEET,

IN CUBIC FEET PER SECOND

0

5

15

20

10

25

30

35

DOWNSTREAM DISCHARGE NEAR AN ALTITUDE OF 45 FEET,

IN MILLION GALLONS PER DAY

0 5 10 15 20 25 30 35

UPSTREAM DISCHARGE NEAR AN ALTITUDE OF 605 FEET, IN MILLION GALLONS PER DAY

UPPER BRACKETING ESTIMATE

RELATION FROM AVAILABLE DATA

LOWER BRACKETING ESTIMATE

MINIMUM UPSTREAM FLOW NEEDED

 TO INITIATE DOWNSTREAM FLOW

Figure 40. Relation between discharge near an altitude of 605 feet and discharge near an altitude of 

45 feet for natural, undiverted conditions, Waiheÿe River, Maui, Hawaiÿi.

Figure 41. Relation between discharge near an altitude of 880 feet in North Waiehu Stream and discharge near an altitude of 20 feet in Waiehu Stream for natural, undiverted conditions, Maui, Hawaiÿi.

0

1

2

3

4

5

0 1 2 3 4 5

0 1 2 3 4 5 6 7 8

0

1

2

3

4

5

6

7

8

UPSTREAM DISCHARGE NEAR AN ALTITUDE OF 880 FEET, IN CUBIC FEET PER SECOND

DOWNSTREAM DISCHARGE NEAR AN ALTITUDE OF 20 FEET,

IN CUBIC FEET PER SECOND

UPSTREAM DISCHARGE NEAR AN ALTITUDE OF 880 FEET, IN MILLION GALLONS PER DAY

DOWNSTREAM DISCHARGE NEAR AN ALTITUDE OF 20 FEET,

IN MILLION GALLONS PER DAY

UPPER BRACKETING ESTIMATE

RELATION FROM AVAILABLE DATA

LOWER BRACKETING ESTIMATE

MINIMUM UPSTREAM FLOW NEEDED

 TO INITIATE DOWNSTREAM FLOW

Figure 41. Relation between discharge near an altitude of 880 feet in North Waiehu Stream and 

discharge near an altitude of 20 feet in Waiehu Stream for natural, undiverted conditions,

Maui, Hawaiÿi.

Natural, Undiverted Low-Flow Characteristics 75
Figure 42. Relation between discharge near an altitude of 780 feet and discharge near an altitude of 35 

feet for natural, undiverted conditions, ÿĪao Stream, Maui, Hawaiÿi.

Figure 43. Relation between discharge near an altitude of 1,160 feet and discharge near an altitude of 

10 feet for natural, undiverted conditions, Waikapü Stream, Maui, Hawaiÿi.

0 5 10 15 20 25 30 35 40

0

5

10

15

20

25

30

35

40

UPSTREAM DISCHARGE NEAR AN ALTITUDE OF 780 FEET, IN CUBIC FEET PER SECOND

DOWNSTREAM DISCHARGE NEAR AN ALTITUDE OF 35 FEET,

IN CUBIC FEET PER SECOND

DOWNSTREAM DISCHARGE NEAR AN ALTITUDE OF 35 FEET,

IN MILLION GALLONS PER DAY

UPSTREAM DISCHARGE NEAR AN ALTITUDE OF 780 FEET, IN MILLION GALLONS PER DAY

0

5

15

20

10

25

0 5 10 15 20 25

UPPER BRACKETING ESTIMATE

RELATION FROM AVAILABLE DATA

LOWER BRACKETING ESTIMATE

MINIMUM UPSTREAM FLOW NEEDED

 TO INITIATE DOWNSTREAM FLOW

Figure 42. Relation between discharge near an altitude of 780 feet and discharge near an

altitude of 35 feet for natural, undiverted conditions, ÿÏao Stream, Maui, Hawaiÿi.

0

4

6

2

8

10

12

0 2 4 6 8 10 12

0 2 4 6 8 10 12 14 16 18 20

0

2

4

6

8

10

12

14

16

18

20

UPSTREAM DISCHARGE NEAR AN ALTITUDE OF 1,160 FEET, IN CUBIC FEET PER SECOND

DOWNSTREAM DISCHARGE NEAR AN ALTITUDE OF 10 FEET,

IN CUBIC FEET PER SECOND

DOWNSTREAM DISCHARGE NEAR AN ALTITUDE OF 10 FEET,

IN MILLION GALLONS PER DAY

UPSTREAM DISCHARGE NEAR AN ALTITUDE OF 1,160 FEET, IN MILLION GALLONS PER DAY

UPPER BRACKETING ESTIMATE

RELATION FROM AVAILABLE DATA

LOWER BRACKETING ESTIMATE

MINIMUM UPSTREAM FLOW NEEDED

 TO INITIATE DOWNSTREAM FLOW

Figure 43. Relation between discharge near an altitude of 1,160 feet and discharge near an

altitude of 10 feet for natural, undiverted conditions, Waikapü Stream, Maui, Hawaiÿi.

76 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
ÿĪao Stream

For ‘Īao Stream, a minimum flow of about 5.2 Mgal/d 

(8.1 ft3/s) near an altitude of 780 ft, corresponding to a 

minimum flow of about 2.1 Mgal/d (3.2 ft3/s) near an altitude 

of 220 ft, is needed to initiate flow near the coast at an altitude 

of 35 ft, assuming no diversions exist downstream of an 

altitude of 780 ft or in any tributaries to ‘Īao Stream (fig. 42). 

The minimum flow estimate of 5.2 Mgal/d (8.1 ft3/s) for ‘Īao 

Stream near an altitude of 780 ft is less than the minimum 

recorded flow of 6.1 Mgal/d (9.4 ft3/s) during climate years 

1984–2007. Thus, during climate years 1984–2007, ‘Īao 

Stream would have flowed continuously to the coast at all 

times if no diversions existed. 

Waikapu ̄ Stream

For Waikapū Stream, a minimum flow of about 6.8 

Mgal/d (11 ft3/s) near an altitude of 1,160 ft, corresponding to 

minimum flows of about 8.0 Mgal/d (12 ft3/s) near an altitude 

of 400 ft and 2.1 Mgal/d (3.2 ft3/s) near an altitude of 40 ft, 

is needed to initiate flow near the coast at an altitude of 10 

ft, assuming no diversions exist downstream of an altitude 

of 1,160 ft or in the unnamed tributary that enters Waikapū 

Stream near an altitude of 1,050 ft (fig. 43). The minimum 

flow estimate of 6.8 Mgal/d (11 ft3/s) for Waikapū Stream near 

an altitude of 1,160 ft is greater than the estimated median 

undiverted flow (4.3 Mgal/d; 6.6 ft3/s) (table 21) during 

climate years 1984–2007 at an altitude of 1,160 ft. Thus, 

during climate years 1984–2007, Waikapū Stream would have 

flowed continuously to the coast less than half of the time if no 

diversions existed. The relation between upstream flow near 

an altitude of 1,160 ft and downstream flow near an altitude 

of 10 ft for Waikapū Stream (fig. 43) required extrapolation 

or use of seepage-run measurements for flows exceeding the 

median flow and, thus, this relation may not accurately reflect 

low-flow conditions and contains much uncertainty.

Recent Diverted Low-Flow 

Characteristics in Streams

During dry-weather conditions in 2006–2008, some 

reaches in each of the Nā Wai ‘Ehā area streams have been 

observed to be dry (no visible water). Waihe‘e River was 

occasionally dry in some reaches immediately downstream of 

the Waihe‘e Ditch intakes and between the Spreckels Ditch 

intake near an altitude of 400 ft and the Field 1 intake near 

an altitude of 260 ft. North Waiehu Stream commonly was 

dry between altitudes of 490 and 280 ft. On the basis of a 

limited number of measurements (table 12) and additional 

visual observations made during this study, diversion of water 

from South Waiehu Stream through two private ‘auwai near 

altitudes of 620 and 570 ft was not known to have caused 

South Waiehu Stream to cease flowing upstream of an altitude 

of 270 ft during the 2006–2008 data-collection period. Near 

an altitude of 270 ft, Spreckels Ditch commonly diverts all 

of the dry-weather flow in South Waiehu Stream, although 

streamflow immediately downstream of the intake may exist 

because of leakage through or subsurface flow beneath the 

dam near the intake. Waiehu Stream was never observed 

to be dry immediately downstream of the confluence of 

North and South Waiehu Streams, although Waiehu Stream 

commonly was dry farther downstream near an altitude of 

20 ft. ‘Īao Stream commonly was observed to be dry near 

altitudes of 370 and 50 ft. Waikapū Stream commonly was 

dry downstream of an altitude of 200 ft. Each stream flows 

continuously from mauka to makai during large storms. 

Waihe‘e River and ‘Īao Stream flow continuously from mauka 

to makai during dry-weather conditions when sufficient flow is 

restored to the stream. 

Following a discharge peak in an undiverted stream, 

streamflow will gradually recede over a period of time that 

is dependent on factors including the volume and duration of 

rainfall, drainage-basin size and steepness, stream-channel 

storage, and permeability of rocks and sedimentary deposits 

through which interflow occurs. In a diverted stream with an 

intake capable of diverting all streamflow below a particular 

level, the recession period immediately downstream of 

the intake will tend to be abruptly truncated. That is, once 

streamflow recedes to a level less than the intake capacity, 

flow passing the diversion intake will cease. Thus, in a 

diverted stream with an intake capable of diverting all of 

the low flow in a stream, recession periods generally will be 

shortened, and this will tend to reduce the time available for 

upstream migration of native stream fauna following a freshet.

Water that originally was diverted from one stream can 

be discharged to another stream, either intentionally through 

release gates in the ditch system or by overflow of ditch or 

flume systems. For example, the Spreckels Ditch flume over 

‘Īao Stream transports water diverted from Waihe‘e River 

and South Waiehu Stream and commonly was observed to 

overflow into ‘Īao Stream during periods of high flow in 

Waihe‘e River (fig. 44). In addition, the Waihe‘e Ditch flumes 

over North and South Waiehu Streams may overflow (fig. 44), 

and discharge from the Spreckels Ditch siphon across South 

Waiehu Stream can exceed the capacity of the system and 

overflow into South Waiehu Stream. 

Low-Flow Partial-Record Stations

Continuous-record stream-gaging stations downstream 

of diversions currently (2009) do not exist in the Nā Wai ‘Ehā 

area. Gaging-station records from 1910–17 can be used to 

characterize historical diverted streamflows, although conditions 

during 1910–17 may not be relevant today because diversion 

configurations and operations may have changed. Low-flow 

partial-record (LFPR) stations commonly are used to estimate 

Recent Diverted Low-Flow Characteristics in Streams 77
low-flow statistics at sites without a long-term stream-gaging 

station. For example, Fontaine and others (1992) used data from 

LFPR stations on windward Oahu perennial streams to estimate 

median discharges at ungaged, regulated sites. Fontaine (2003) 

also used LFPR stations to estimate regulated discharges, within 

the Q50 to Q95 range, in Honokōhau Stream. 

At LFPR stations, a minimum of about 10 discharge 

measurements generally are made during periods of low 

flow. These measurements are best made during independent 

recessions following periods of direct runoff and cover a range 

of low-flow conditions. The measured discharges at each LFPR 

station are correlated with the concurrent daily mean discharges 

at a long-term index station with hydrologically similar 

characteristics. For this study, LFPR stations were established 

on each stream and the measured discharges were correlated 

with concurrent daily mean discharges from ‘Īao Stream 

(16604500) and Waihe‘e River (16614000). Discharges at the 

LFPR stations affected by diversions were poorly correlated 

(correlation coefficients commonly less than 0.5 and in some 

cases less than 0.1) with concurrent discharges at the index 

stations for a number of reasons: (1) some of the diversion 

intakes are capable of diverting all of the dry-weather low 

flow of the stream, and this results in sites downstream of the 

intakes having near-zero flow for a range of low flows at the 

index station; (2) ditches and flumes that carry water from one 

stream (for example Waihe‘e River) may overflow into another 

stream (for example South Waiehu Stream or ‘Īao Stream) and 

affect the flow characteristics of the receiving stream (fig. 44); 

(3) during ditch-maintenance periods, flow may be restored 

temporarily to a stream for periods of various lengths (fig. 45); 

A

B

direction of

streamow

direction of

streamow

ditch return ow

ditch return ow

Figure 45. Photographs of diverted water being returned to 

streams during periods of ditch maintenance, Maui, Hawaiÿi. 

A, Water being returned to ÿĪao Stream near an altitude of 

220 feet (February 13, 2008). B, Water being returned to 

Waiheÿe River near an altitude of 320 feet (November 17, 

2008).

A

B

ume overow

direction of

streamow

ditch return ow

Figure 44. Photographs of overflowing flumes discharging water originating from one stream into another stream, 

Maui, Hawaiÿi. A, Spreckels Ditch overflowing into ÿĪao 

Stream near an altitude of 220 feet (September 19, 2007). 

B, Waiheÿe Ditch overflowing into South Waiehu Stream 

near an altitude of 550 feet (July 17, 2006).

78 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
(4) return of diverted water to streams may be affected by the 

size of the opening of the return gate, which can be manually 

raised or lowered; (5) intake grates may divert variable rates of 

water for the same upstream flow because of natural clogging 

by rocks and debris or human activities (fig. 46); and (6) the 

amount of water diverted by North Waiehu Ditch was dependent 

on both streamflow and the condition of the rock-wall diversion 

dam. Thus, estimates of diverted-flow statistics from the LFPR 

stations were not made for this study. 

Flow Characterization from Mounted Cameras

Hourly photographs from cameras mounted at 11 sites 

downstream of existing diversions were used to characterize 

how frequently each stream was dry (no visible water) near the 

camera site. For each stream, a camera was mounted at low 

altitude to provide information on how frequently the stream 

flowed near the coast. Additional cameras were mounted 

immediately downstream of selected diversion intakes and 

at other sites where access was safe, a suitable mounting 

structure was available, and where the camera would not be 

readily detected. In some cases, photographs were limited to 

daylight hours. In addition, hourly photographs sometimes 

were not taken by the cameras, even though they were 

programmed to record on an hourly basis. 

Waiheÿe River

Cameras were mounted a few hundred feet downstream 

of the intakes for both the Waihe‘e and Spreckels Ditches, 

respectively near altitudes of 560 and 390 ft, and farther 

downstream near an altitude of 45 ft in Waihe‘e River. 

Photographs are available from October 2006 to April 2008 

near an altitude of 560 ft; from October 2006 to December 

2008 near an altitude of 390 ft; and from September 2006 to 

September 2008 near an altitude of 45 ft. The camera mounted 

near an altitude of 560 ft was vandalized sometime between 

May 1 and May 28, 2008. 

None of the photographs indicate completely dry stream 

reaches, although photographs from altitudes of 560 and 390 ft 

commonly show highly diverted flow conditions with estimated 

flows less than 0.06 Mgal/d (0.1 ft3/s). Photographs from the 

camera near an altitude of 45 ft indicate continuous flow. 

Waiehu Stream

 Cameras were mounted near an altitude of 490 ft in North 

Waiehu Stream and near an altitude of 20 ft in Waiehu Stream. 

Photographs are available from September 2006 to July 2008 

near an altitude of 490 ft in North Waiehu Stream and from 

February 2007 to December 2008 near an altitude of 20 ft in 

Waiehu Stream. Available photographs indicate that North 

Waiehu Stream was dry about 75 percent of the time and Waiehu 

Stream was dry about 57 percent of the time during the periods 

of record. During the 2007 climate year (April 1, 2007, through 

March 31, 2008), North Waiehu Stream was dry 77 percent of 

the time and Waiehu Stream was dry 45 percent of the time. 

ÿĪao Stream

Cameras were mounted near altitudes of 720, 370, and 50 ft 

in ‘Īao Stream. Photographs are available from September 2006 

to October 2008 near an altitude of 720 ft; from September 2006 

to December 2008 near an altitude of 370 ft; and from September 

2006 to May 2008 near an altitude of 50 ft. The camera mounted 

near an altitude of 50 ft was first noted missing on July 1, 2008. 

Available photographs indicate that ‘Īao Stream was never 

completely dry near an altitude of 720 ft, mainly because ‘Īao 

Stream gains water between the common intake for the ‘ĪaoWaikapū and ‘Īao-Māniania Ditches and the camera site (fig. 34). 

Near altitudes of 370 and 50 ft, ‘Īao Stream was dry about 28 and 

66 percent of the time, respectively, during the periods of record 

at each site. During the 2007 climate year, ‘Īao Stream was dry 

about 20 and 66 percent of the time near altitudes of 370 and 50 

ft, respectively. The intake for Spreckels Ditch on ‘Īao Stream is 

between the camera sites near altitudes of 370 and 50 ft. 

Waikapu ̄ Stream

Cameras were mounted near altitudes of 400, 200, 

and 40 ft in Waikapū Stream. Photographs are available 

from August 2006 to May 2009 near an altitude of 400 ft; 

from August 2006 to April 2009 near an altitude of 200 ft; 

and from April 2008 to May 2009 near an altitude of 40 ft. 

Available photographs indicate that near altitudes of 400, 

200, and 40 ft, Waikapū Stream was dry about 3, 44, and 76 

Figure 46. Photograph of partially covered (with blue tarp) diversion intake 

common to the ÿÏao-Mäniania and ÿÏao-Waikapü Ditches near an altitude of 

780 feet, ÿÏao Stream, Maui, Hawaiÿi (July 30, 2007). 

Figure 46. Photograph of partially covered (with blue tarp) 

diversion intake common to the ÿĪao-Mäniania and ÿĪaoWaikapü Ditches near an altitude of 780 feet, ÿĪao Stream, 

Maui, Hawaiÿi (July 30, 2007).

Recent Diverted Low-Flow Characteristics in Streams 79
percent of the time, respectively, during the periods of record 

at each site. During the 2007 climate year, Waikapū Stream 

was dry about 1 and 28 percent of the time near altitudes of 

400 and 200 ft, respectively. Available data during the 2008 

climate year indicate that Waikapū Stream was dry about 7, 

63, and 78 percent of the time near altitudes of 400, 200, and 

40 ft, respectively. (The camera near an altitude of 40 ft was 

installed on April 29, 2008, and, thus, data during April 1 thru 

April 28, 2008, are not available.)

The increased frequency of dry conditions in a 

downstream direction is consistent with the presence of a 

losing reach between altitudes of 400 and 40 ft (fig. 35). The 

lack of continuous flow to the ocean from Waikapū Stream is 

consistent with observations by Martin and Pierce (1913, p. 

225), who indicated that only storm water reaches the ocean 

from Waikapū Stream. 

Effects of Surface-Water Diversions on 

Streamflow 

Diversion of surface water from a stream reduces the 

amount of water available at downstream sites. The seepagerun measurements were used to develop relations between 

upstream and downstream flows of selected reaches in each 

stream (see section on “Seepage-Run Measurements” and 

figs. 32–39), and these relations were used to estimate the 

effects of surface-water diversions on streamflow at selected 

sites downstream of diversions. The method used to estimate 

streamflow at sites downstream of diversions is similar to 

the method used to estimate natural, undiverted flows at 

ungaged sites, except that water diverted from streams must be 

considered. For each stream, natural flows upstream of existing 

diversions were used as a starting point for determining 

selected duration discharges for sites downstream of diversions 

(tables 18–21). 

As the capacity of a diversion intake increases, the reduction 

in streamflow at downstream sites generally increases. To estimate 

the effects of surface-water diversions on streamflow for this 

study, diversions are assumed to be capable of diverting water at a 

rate up to, but not exceeding, the diversion intake capacity. Thus, if 

streamflow immediately upstream of an intake is less than or equal 

to the intake capacity, all available streamflow is assumed to be 

diverted. (In reality, some flow may bypass the diversion intake for 

upstream flows less than the intake capacity, although the relation 

between upstream flow and bypass flow is not known. Thus, for 

the purposes of this study, the simplifying assumption was made 

that this bypass flow is small.) At some level of diversion intake 

capacity the diversions may cause downstream sites to be dry, 

and increased diversion intake capacity has no further effect on 

reducing streamflow during dry-weather, low-flow conditions. 

The effects of the diversions on streamflow at downstream sites 

were determined at selected upstream flows equal to and less than 

the median flow. For the purposes of this analysis, none of the 

diverted water is assumed to return to the stream, and the intake 

capacity of a diversion is assumed to be unaffected by water, 

possibly derived from another stream, already in the ditch system. 

Using the natural flows upstream of existing diversions 

and estimated gains or losses from seepage-run measurements, 

duration discharges at downstream sites were determined for 

selected diversion intake capacities. For most cases, estimated 

losses in a reach were assumed to be constant, independent of flow 

rate, and uniformly distributed along the reach. Thus, if a diversion 

intake is located in the middle of a reach, then half of the loss is 

assumed to occur upstream and half of the loss is assumed to occur 

downstream of the intake. If the intake is capable of diverting all 

of the flow remaining in the stream, after accounting for losses in 

the upstream reach, then streamflow and losses downstream of the 

intake are zero. For two reaches (one between altitudes of 880 and 

475 ft on North Waiehu Stream and the other between altitudes of 

190 and 20 ft on Waiehu Stream), estimated losses are assumed to 

be a function of streamflow at the upstream end of the reach (fig. 

36). The intake for the North Waiehu Ditch is at the upstream end 

of the reach on North Waiehu Stream between altitudes of 880 and 

475 ft and, thus, diversion amounts are simply subtracted from 

the natural, undiverted upstream flow. No diversions are known to 

exist in the reach on Waiehu Stream between altitudes of 190 and 

20 ft. 

Waihe‘e River

Selected duration discharges (Q50, Q70, and Q90) for 

Waihe‘e River near altitudes of 590, 390, and 45 ft were 

determined for diversion intake capacities of 0 to 39 Mgal/d (0 

to 60 ft3/s) for the Waihe‘e Ditch; 0 to 39 Mgal/d (0 to 60 ft3/s) 

for Spreckels Ditch; and 0 or 3.2 Mgal/d (0 or 5 ft3/s) for the 

Field 1 intake (figs. 47–48). The intake capacity for the Field 1 

diversion is unknown and, thus, the use of 3.2 Mgal/d (5 ft3/s) 

for the intake capacity of the Field 1 intake is arbitrary. For 

each duration discharge (Q50, Q70, or Q90) near altitudes of 390 

and 45 ft, a family of curves, with each curve corresponding to 

a particular flow near an altitude of 390 ft (fig. 47B) or near the 

coast at an altitude of 45 ft (fig. 48), was developed to show the 

relation between diversion intake capacities and streamflow. 

Using the approximate diversion capacity settings of 40 

Mgal/d (62 ft3

/s) for the Waihe‘e Ditch and 12 Mgal/d (18 

ft3/s) for Spreckels Ditch (Suzuki, 2007), estimated median 

streamflows near altitudes of 390 and 45 ft are zero (figs. 

47–48). Thus, if both Waihe‘e and Spreckels Ditches divert at 

their reported capacities and no water is returned to Waihe‘e 

River, then zero flow may occur at least 50 percent of the 

time downstream of the Spreckels Ditch intake (assuming 

no subsurface leakage immediately downstream of existing 

diversion structures contributes to streamflow). 

Combinations of diversion intake capacities that result 

in a specified flow near the coast at an altitude of 45 ft can be 

estimated using the family of curves (fig. 48). For example, 

to maintain a median flow of 12.9 Mgal/d (20 ft3

/s) near an 

altitude of 45 ft, assuming no water is diverted at the Field 1 

intake, different combinations of diversion intake capacities for 

80 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Waihe‘e and Spreckels Ditches equal to 19.6 Mgal/d (30.4 

ft3/s) are possible (see fig. 48A, Q50). Thus, if the intake 

capacity for the Waihe‘e Ditch is19.6 Mgal/d (30.4 ft3

/s) 

and no water is diverted by Spreckels Ditch or the Field 1 

intake, then the estimated median flow is 12.9 Mgal/d (20 

ft3/s) near an altitude of 45 ft (fig. 48A, Q50). Similarly, if 

the intake capacities for the Waihe‘e and Spreckels Ditches 

are each 9.8 Mgal/d (15.2 ft3/s), then the estimated median 

flow remains 12.9 Mgal/d (20 ft3/s) near an altitude of 45 ft 

(fig. 48A). For combinations of diversion intake capacities 

from Waihe‘e and Spreckels Ditches equal to 19.6 Mgal/d 

(30.4 ft3/s), the corresponding Q70 and Q90 discharges near 

an altitude of 45 ft, assuming no water is diverted at the 

Field 1 intake, are estimated to be about 7.8 and 3.2 Mgal/d 

(12.0 and 5.0 ft3

/s), respectively (fig. 48A).

Waiehu Stream

To estimate the streamflow in Waiehu Stream downstream 

of diversions from North and South Waiehu Streams, natural 

flows (upstream of all diversions) in each stream at common flowduration percentiles were assumed to occur concurrently. Selected 

duration discharges (Q50, Q70, and Q90) for Waiehu Stream near 

altitudes of 190 and 20 ft were determined for diversion intake 

capacities of 0 to 3.2 Mgal/d (0 to 5 ft3/s) for North Waiehu Ditch, 

North Waiehu Stream; 0 to 3.2 Mgal/d (0 to 5 ft3/s) for Spreckels 

Ditch, South Waiehu Stream; and 0 or 0.32 Mgal/d (0 or 0.5 ft3

/s) 

each for two existing private ‘auwai with intakes near altitudes of 

620 and 570 ft, South Waiehu Stream (figs. 49–50). The diversion 

intake capacities for the two existing private ‘auwai are unknown 

and variable, depending on the condition of the intakes. For this 

study, the intake capacity of each private ‘auwai was assumed 

0 10 20 30 40 50

0 10 15 5 20 25 30 35 0 10 15 5 20 25 30 35 0 10 15 5 20 25 30 35

60 0 10 20 30 40 50 60 0 10 20 30 40

Q50 Q70 Q90

Q50 Q70 Q90

50 60

0

10

20

0

5

10

15

20

25

35

30

30

40

50

60

0

10

20

0

5

10

15

20

25

30

35

30

50

40

60

CAPACITY OF WAIHEÿE DITCH INTAKES, WAIHEÿE RIVER, IN CUBIC FEET PER SECOND

CAPACITY OF WAIHEÿE DITCH INTAKES, WAIHEÿE RIVER, IN MILLION GALLONS PER DAY

CAPACITY OF SPRECKELS DITCH INTAKE,

WAIHEÿE RIVER, IN CUBIC FEET PER SECOND

DISCHARGE NEAR AN ALTITUDE OF 590 FEET,

WAIHEÿE RIVER, IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE,

WAIHEÿE RIVER, IN MILLION GALLONS PER DAY

DISCHARGE NEAR AN ALTITUDE OF 590 FEET,

WAIHEÿE RIVER, IN MILLION GALLONS PER DAY

A

B

0

40

50

30

20

10

0

30

40

20

10

0

10

20

30

LINE OF EQUAL ESTIMATED 

DISCHARGE FOR WAIHEÿE RIVER

NEAR AN ALTITUDE OF 390 FEET, 

IN CUBIC FEET PER SECOND--

Interval 2 cubic feet per second

10

Figure 47. Estimated discharges (Q50, Q70, and Q90) in Waiheÿe River, Maui, Hawaiÿi, resulting from diversions into the Waiheÿe Ditch

and Spreckels Ditch with indicated hypothetical intake capacities. A, Near an altitude of 590 feet, downstream of the intakes for the

Waiheÿe Ditch. B, Near an altitude of 390 feet, downstream of the intake for Spreckels Ditch. The Q50, Q70, and Q90 discharges represent

the discharges that are equaled or exceeded 50, 70, and 90 percent of the time, respectively. A ditch intake is assumed to divert at a

rate up to, but not exceeding, the indicated capacity (if streamflow is less than the indicated capacity, then all streamflow at the ditch 

intake is assumed to be diverted). 

Figure 47. Estimated discharges (Q50, Q70, and Q90) in Waiheÿe River, Maui, Hawaiÿi, resulting from diversions into the 

Waiheÿe Ditch and Spreckels Ditch with indicated hypothetical intake capacities. A, Near an altitude of 590 feet, downstream 

of the intakes for the Waiheÿe Ditch. B, Near an altitude of 390 feet, downstream of the intake for Spreckels Ditch. The Q50, 

Q70, and Q90 discharges represent the discharges that are equaled or exceeded 50, 70, and 90 percent of the time, respectively. A ditch intake is assumed to divert at a rate up to, but not exceeding, the indicated capacity (if streamflow is less than 

the indicated capacity, then all streamflow at the ditch intake is assumed to be diverted).

Effects of Surface-Water Diversions on Streamflow 81
to be either 0 or 0.32 Mgal/d (0 or 0.5 ft3

/s), which generally 

represents the range of available measured diversion rates during 

this study (table 12). For each duration discharge (Q50, Q70, or Q90) 

near altitudes of 190 and 20 ft, a family of curves, with each 

curve corresponding to a particular flow near an altitude of 

190 ft (fig. 49) or near the coast at an altitude of 20 ft (fig. 50), 

was developed to show the relation between diversion intake 

capacities and streamflow. 

Using the reported diversion capacity of 1.5 Mgal/d (2.3 

ft3/s) for the North Waiehu Ditch (Suzuki, 2007) and a diversion 

intake capacity of 1.3 Mgal/d (2 ft3/s) for Spreckels Ditch, 

estimated median streamflows in Waiehu Stream near altitudes 

of 190 and 20 ft were about a third of the values for natural, 

undiverted conditions (assuming no water is returned to the 

stream, no water is diverted by each of the two existing private 

‘auwai on South Waiehu Stream, and no leakage immediately 

downstream of diversion structures contributes to streamflow) 

(figs. 49–50). Using the reported diversion capacity of 1.5 

Mgal/d (2.3 ft3/s) for the North Waiehu Ditch (Suzuki, 2007), 

diversion intake capacities of 0.32 Mgal/d (0.5 ft3/s) each for two 

existing private ‘auwai with intakes near altitudes of 620 and 

570 ft in South Waiehu Stream, and a diversion intake capacity 

of 1.3 Mgal/d (2 ft3/s) for Spreckels Ditch, estimated median 

streamflows in Waiehu Stream near altitudes of 190 and 20 ft 

were less than 1 Mgal/d (1.5 ft3/s) (assuming no water is returned 

to the stream) (figs. 49–50). For these diversion intake capacities, 

Waiehu Stream may have zero flow at least 30 percent of the 

time near an altitude of 20 ft (fig. 50B). Even for the case of no 

diversions, available data indicate that Waiehu Stream near an 

altitude of 20 ft may have zero flow between 1 and 5 percent of 

the time (table 19).

Combinations of diversion intake capacities that result 

in a specified flow near the coast at an altitude of 20 ft can be 

estimated using the family of curves (fig. 50). For example, to 

maintain a median flow of 0.65 Mgal/d (1 ft3/s) near an altitude 

of 20 ft, assuming diversion intake capacities of 0.32 Mgal/d (0.5 

0 10 20 30 40 50

0 10 15 5 20 25 30 35 0 10 15 5 20 25 30 35 0 10 15 5 20 25 30 35

60 0 10 20 30 40 50 60 0 10 20 30 40

Q50 Q70 Q90

Q50 Q70 Q90

50 60

0

10

20

0

5

10

15

20

25

35

30

30

40

50

60

0

10

20

0

5

10

15

20

25

30

35

30

50

40

60

CAPACITY OF WAIHEÿE DITCH INTAKES, WAIHEÿE RIVER, IN CUBIC FEET PER SECOND

CAPACITY OF WAIHEÿE DITCH INTAKES, WAIHEÿE RIVER, IN MILLION GALLONS PER DAY

CAPACITY OF SPRECKELS DITCH INTAKE, WAIHEÿE RIVER, IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE, WAIHEÿE RIVER, IN MILLION GALLONS PER DAY

A

B

0

40

30

20

10

0

30

40

20

10

0

10

20

30

0

30

20

10

0

10

20

0

10

20

30

LINE OF EQUAL ESTIMATED 

DISCHARGE FOR WAIHEÿE RIVER

NEAR AN ALTITUDE OF 45 FEET, 

IN CUBIC FEET PER SECOND--

Interval 2 cubic feet per second

10

Figure 48. Estimated discharges (Q50, Q70, and Q90) in Waiheÿe River near an altitude of 45 feet, Maui, Hawaiÿi, resulting from diversions 

into the Waiheÿe Ditch and Spreckels Ditch with indicated hypothetical intake capacities. A, Zero diversion into the Field 1 intake. B, Diversion 

capacity of 3.2 million gallons per day (5 cubic feet per second) for the Field 1 intake. The Q50, Q70, and Q90 discharges represent the 

discharges that are equaled or exceeded 50, 70, and 90 percent of the time, respectively. A ditch intake is assumed to divert at a rate up 

to, but not exceeding, the indicated capacity (if streamflow is less than the indicated capacity, then all streamflow at the ditch intake is 

assumed to be diverted). 

Figure 48. Estimated discharges (Q50, Q70, and Q90) in Waiheÿe River near an altitude of 45 feet, Maui, Hawaiÿi, resulting 

from diversions into the Waiheÿe Ditch and Spreckels Ditch with indicated hypothetical intake capacities. A, Zero diversion 

into the Field 1 intake. B, Diversion capacity of 3.2 million gallons per day (5 cubic feet per second) for the Field 1 intake. 

The Q50, Q70, and Q90 discharges represent the discharges that are equaled or exceeded 50, 70, and 90 percent of the time, 

respectively. A ditch intake is assumed to divert at a rate up to, but not exceeding, the indicated capacity (if streamflow is 

less than the indicated capacity, then all streamflow at the ditch intake is assumed to be diverted).

82 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
ft3

/s) each for the two existing private ‘auwai with intakes near 

altitudes of 620 and 570 ft in South Waiehu Stream, different 

combinations of diversion intake capacities for North Waiehu and 

Spreckels Ditches are possible (see fig. 50B, Q50). For a diversion 

intake capacity of 0.85 Mgal/d (1.31 ft3

/s) for North Waiehu 

Ditch and diversion intake capacities of 0.32 Mgal/d (0.5 ft3/s) 

each for the two existing private ‘auwai in South Waiehu Stream, 

a diversion intake capacity of at least 1.60 Mgal/d (2.48 ft3/s) 

for Spreckels Ditch will result in a median flow of 0.65 Mgal/d 

(1 ft3/s) near an altitude of 20 ft. Diversion intake capacities 

greater than 1.60 Mgal/d (2.48 ft3/s) for Spreckels Ditch cause 

median flow in South Waiehu Stream to be zero downstream of 

the Spreckels Ditch intake, and, thus, diversion intake capacities 

greater than 1.60 Mgal/d (2.48 ft3/s) for Spreckels Ditch do not 

reduce further the low flow in Waiehu Stream. This is shown by 

the vertical lines (fig. 50B, Q50) for diversion intake capacities 

greater than 1.60 Mgal/d (2.48 ft3

/s) for Spreckels Ditch. For 

a diversion intake capacity of at least 1.94 Mgal/d (3.00 ft3

/s) 

for North Waiehu Ditch and diversion intake capacities of 0.32 

Mgal/d (0.5 ft3/s) each for the two existing private ‘auwai in 

South Waiehu Stream, a diversion intake capacity of 0.76 Mgal/d 

(1.18 ft3/s) for Spreckels Ditch also will result in a median flow 

of 0.65 Mgal/d (1 ft3

/s) near an altitude of 20 ft. Diversion intake 

capacities greater than 1.94 Mgal/d (3.00 ft3/s) for North Waiehu 

Ditch cause flow in North Waiehu Stream to be zero downstream 

of an altitude of 280 ft, and, thus, diversion intake capacities 

greater than 1.94 Mgal/d (3.00 ft3/s) for North Waiehu Ditch do 

not reduce further the low flow in Waiehu Stream. This is shown 

by the horizontal lines (fig. 50B, Q50) for diversion intake intake 

capacities greater than 1.94 Mgal/d (3.00 ft3/s) for North Waiehu 

Ditch. For diversion intake capacities that result in a median 

discharge of 0.65 Mgal/d (1 ft3/s) near an altitude of 20 ft, (1) the 

estimated Q70 discharge near an altitude of 20 ft ranges from zero 

to 0.14 Mgal/d (0.21 ft3/s), depending on the diversion intake 

capacities of North Waiehu and Spreckels Ditches, and (2) the 

estimated Q90 discharge near an altitude of 20 ft is zero (fig. 50B).

0 1 2 3 4

0 0.5 1.0 1.5 2.0 2.5 3.0 0 0.5 1.0 1.5 2.0 2.5 3.0 0 0.5 1.0 1.5 2.0 2.5 3.0

5 0 1 2 3 4 5 0 1 2 3 4

Q50 Q70 Q90

Q50 Q70 Q90

5

0

1

2

3

4

0

1.0

0.5

1.5

2.0

2.5

3.0

5

0

1

2

3

4

0

1.0

0.5

1.5

2.0

2.5

3.0

5

CAPACITY OF NORTH WAIEHU DITCH INTAKE, NORTH WAIEHU STREAM, IN CUBIC FEET PER SECOND

CAPACITY OF NORTH WAIEHU DITCH INTAKE, NORTH WAIEHU STREAM, IN MILLION GALLONS PER DAY

CAPACITY OF SPRECKELS DITCH INTAKE, SOUTH WAIEHU STREAM, IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE, SOUTH WAIEHU STREAM, IN MILLION GALLONS PER DAY

A

B

1

1

1

0.4

3

2

2

3

1

2

3

4

1

2

4

5

0.60.2

LINE OF EQUAL ESTIMATED 

DISCHARGE FOR WAIEHU STREAM 

NEAR AN ALTITUDE OF 190 FEET, 

IN CUBIC FEET PER SECOND--

Interval 0.2 cubic feet per second

2

Figure 49. Estimated discharges (Q50, Q70, and Q90) in Waiehu Stream near an altitude of 190 feet, Maui, Hawaiÿi, resulting from diversions into the North Waiehu Ditch and Spreckels Ditch with indicated hypothetical intake capacities. A, Zero 

diversion into two private ÿauwai (ditches) near altitudes of 620 and 570 feet, South Waiehu Stream. B, Combined diversion 

capacity of 0.65 million gallons per day (1 cubic foot per second) for two private ÿauwai near altitudes of 620 and 570 feet, 

South Waiehu Stream. The Q50, Q70, and Q90 discharges represent the discharges that are equaled or exceeded 50, 70, 

and 90 percent of the time, respectively. A ditch intake is assumed to divert at a rate up to, but not exceeding, the indicated 

capacity (if streamflow is less than the indicated capacity, then all streamflow at the ditch intake is assumed to be diverted).

Effects of Surface-Water Diversions on Streamflow 83
was developed to show the relation between diversion intake 

capacities and streamflow.

Using the reported diversion capacity for the common 

intake of the ‘Īao-Waikapū and ‘Īao-Māniania Ditches of 20 

Mgal/d (31 ft3/s) (Suzuki, 2007) and a diversion intake capacity 

of 3.9 Mgal/d (6 ft3/s) for Spreckels Ditch, estimated median 

streamflows near altitudes of 220 and 35 ft are zero, assuming no 

water is returned to the stream (figs. 51–52). For the case of no 

diversions, ‘Īao Stream near an altitude of 35 ft is estimated to 

have a Q99 flow of 3.4 Mgal/d (5.2 ft3/s) (table 20). 

Combinations of diversion intake capacities that result 

in a specified flow near the coast at an altitude of 35 ft can be 

estimated using the family of curves (fig. 52). For example, 

to maintain a median flow of 6.5 Mgal/d (10 ft3/s) near an 

altitude of 35 ft, assuming an intake capacity of 0.65 Mgal/d 

(1 ft3/s) for the private ‘auwai near an altitude of 650 ft, 

different combinations of diversion intake capacities for the 

ÿÏao Stream

Selected duration discharges (Q50, Q70, and Q90) for ‘Īao 

Stream near altitudes of 220 and 35 ft were determined for 

diversion intake capacities of 0 to 26 Mgal/d (0 to 40 ft3

/s) for 

the ‘Īao-Waikapū and ‘Īao-Māniania Ditches; 0 to 26 Mgal/d 

(0 to 40 ft3

/s) for Spreckels Ditch; and 0 or 0.65 Mgal/d (0 or 1 

ft3

/s) for an existing private ‘auwai with an intake at an altitude 

of about 650 ft (figs. 51–52). The diversion intake capacity for 

the existing private ‘auwai is unknown but much less than the 

current diversion intake capacities for the ‘Īao-Waikapū and 

‘Īao-Māniania Ditches and Spreckels Ditch. The range selected 

for the private ‘auwai covers the range of available measured 

diversion rates (table 12). For each duration discharge (Q50, Q70, 

or Q90) near altitudes of 220 and 35 ft, a family of curves, with 

each curve corresponding to a particular flow near an altitude of 

220 ft (fig. 51) or near the coast at an altitude of 35 ft (fig. 52), 

0 1 2 3 4

0 0.5 1.0 1.5 2.0 2.5 3.0 0 0.5 1.0 1.5 2.0 2.5 3.0 0 0.5 1.0 1.5 2.0 2.5 3.0

5 0 1 2 3 4 5 0 1 2 3 4

Q50 Q70 Q90

Q50 Q70 Q90

5

0

1

2

3

4

0

1.0

0.5

1.5

2.0

2.5

3.0

5

0

1

2

3

4

0

1.0

0.5

1.5

2.0

2.5

3.0

5

CAPACITY OF NORTH WAIEHU DITCH INTAKE, NORTH WAIEHU STREAM, IN CUBIC FEET PER SECOND

CAPACITY OF NORTH WAIEHU DITCH INTAKE, NORTH WAIEHU STREAM, IN MILLION GALLONS PER DAY

CAPACITY OF SPRECKELS DITCH INTAKE, SOUTH WAIEHU STREAM, IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE, SOUTH WAIEHU STREAM, IN MILLION GALLONS PER DAY

A

B

0

1

0

1

0

0.4

2

2

3

0

1

2

3

0

1

4

0

LINE OF EQUAL ESTIMATED 

DISCHARGE FOR WAIEHU STREAM 

NEAR AN ALTITUDE OF 20 FEET, 

IN CUBIC FEET PER SECOND--

Interval 0.2 cubic feet per second

2

Figure 50. Estimated discharges (Q50, Q70, and Q90) in Waiehu Stream near an altitude of 20 feet, Maui, Hawaiÿi, resulting from diversions into the North Waiehu Ditch and Spreckels Ditch with indicated hypothetical intake capacities. A, Zero 

diversion into two private ÿauwai (ditches) near altitudes of 620 and 570 feet, South Waiehu Stream. B, Combined diversion 

capacity of 0.65 million gallons per day (1 cubic foot per second) for two private ÿauwai near altitudes of 620 and 570 feet, 

South Waiehu Stream. The Q50, Q70, and Q90 discharges represent the discharges that are equaled or exceeded 50, 70, 

and 90 percent of the time, respectively. A ditch intake is assumed to divert at a rate up to, but not exceeding, the indicated 

capacity (if streamflow is less than the indicated capacity, then all streamflow at the ditch intake is assumed to be diverted).

84 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
‘Īao-Waikapū and ‘Īao-Māniania Ditches and Spreckels Ditch 

equal to 14.2 Mgal/d (21.9 ft3/s) are possible (see fig. 52B, 

Q50). All combinations of diversion intake capacities that result 

in a median flow of 6.5 Mgal/d (10 ft3/s) near an altitude of 35 

ft result in Q70 and Q90 discharges near an altitude of 35 ft of 

zero (fig. 52).

Waikapu ̄ Stream

Selected duration discharges (Q50, Q70, and Q90) for 

Waikapū Stream near an altitude of 400 ft were determined 

for diversion intake capacities of 0 to 6.5 Mgal/d (0 to 10 

ft3/s) for the South Side Ditch; 0 to 6.5 Mgal/d (0 to 10 

ft3/s) for the combined capacity of a private ‘auwai with 

an intake near an altitude of 560 ft, Waihe‘e Ditch, and the 

Reservoir 6 diversion; and 0 or 0.65 Mgal/d (0 or 1 ft3/s) for 

Everett Ditch. The diversion intake capacity of the Everett 

Ditch is unknown and, thus, values that cover the range of 

available measured diversion rates (table 12) were used. For 

each duration discharge (Q50, Q70, or Q90) near an altitude of 

400 ft, a family of curves, with each curve corresponding 

to a particular flow near an altitude of 400 ft (fig. 53), was 

developed to show the relation between diversion intake 

capacities and streamflow.

For natural-flow conditions, Waikapū Stream may flow 

continuously to an altitude of 400 ft, although the estimated 

median flow downstream near an altitude of 40 ft is zero (table 

21). Using the reported diversion capacity of the South Side 

Ditch of 3 Mgal/d (4.6 ft3/s) (Suzuki, 2007) and a combined 

diversion intake capacity of at least 2.6 Mgal/d (4 ft3/s) for the 

private ‘auwai near an altitude of 560 ft, Waihe‘e Ditch, and 

the Reservoir 6 diversion, the estimated median flow near an 

altitude of 400 ft is zero, assuming no water is returned to the 

stream (fig. 53). 

0 10 15 5 20 25

0 5 10 15 20 25 0 5 10 15 20 25 0 5 10 15 20 25

30 35 40 0 10 15 5 20 25 30 35 40 0 10 15 5 20

Q50 Q70 Q90

Q50 Q70 Q90

25 30 35 40

0

5

10

15

20

25

30

35

40

0

5

10

15

20

25

0

5

10

15

20

25

0

5

10

15

20

25

30

35

40

CAPACITY OF COMMON INTAKE FOR ÿÏAO-MÄNIANIA AND ÿÏAO-WAIKAPÜ DITCHES, ÿÏAO STREAM, IN CUBIC FEET PER SECOND

CAPACITY OF COMMON INTAKE FOR ÿÏAO-MÄNIANIA AND ÿÏAO-WAIKAPÜ DITCHES, ÿÏAO STREAM, IN MILLION GALLONS PER DAY

CAPCITY OF SPRECKELS DITCH INTAKE, ÿÏAO STREAM, IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE, ÿÏAO STREAM, IN MILLION GALLONS PER DAY

A

B

0

24

32

28

20

16

12

4

8

0

24

28

32

20

16

12

4

8

0

12

16

20

4

8

0

12

20

16

4

8

4

0

8

4

0

8

12

LINE OF EQUAL ESTIMATED 

DISCHARGE FOR ÿÏAO STREAM 

NEAR AN ALTITUDE OF 220 FEET, 

IN CUBIC FEET PER SECOND--

Interval 2 cubic feet per second

4

Figure 51. Estimated discharges (Q50, Q70, and Q90) in ÿĪao Stream near an altitude of 220 feet, Maui, Hawaiÿi, resulting 

from diversions into the ÿĪao-Ma ̄niania and ÿĪao-Waikapu ̄ Ditches and Spreckels Ditch with indicated hypothetical intake 

capacites. A, Zero diversion into a private ÿauwai (ditch) near an altitude of 650 feet. B, Diversion capacity of 0.65 million 

gallons per day (1 cubic foot per second) for a private ÿauwai near an altitude of 650 feet. The Q50, Q70, and Q90 discharges 

represent the discharges that are equaled or exceeded 50, 70, and 90 percent of the time, respectively. A ditch intake is 

assumed to divert at a rate up to, but not exceeding, the indicated capacity (if streamflow is less than the indicated capacity, then all streamflow at the ditch intake is assumed to be diverted).

Effects of Surface-Water Diversions on Streamflow 85
Combinations of diversion intake capacities that result in a 

specified flow near an altitude of 400 ft can be estimated using 

the family of curves (fig. 53). For example, to maintain a median 

flow of 1.3 Mgal/d (2 ft3/s) near an altitude of 400 ft, assuming a 

diversion intake capacity of 0.65 Mgal/d (1 ft3/s) for the Everett 

Ditch, different combinations of the diversion intake capacity for 

the South Side Ditch and combined diversion intake capacity for 

the private ‘auwai near an altitude of 560 ft, Waihe‘e Ditch, and 

the Reservoir 6 diversion are possible (see fig. 53B, Q50). Thus, if 

the intake capacity for the South Side Ditch is 3.32 Mgal/d (5.13 

ft3/s) and no water is diverted by the private ‘auwai near an altitude 

of 560 ft, Waihe‘e Ditch, and the Reservoir 6 diversion, then the 

estimated median flow is 1.3 Mgal/d (2 ft3/s) near an altitude 

of 400 ft (fig. 53B, Q50). Similarly, if the intake capacity for the 

South Side Ditch is 1.66 Mgal/d (2.56 ft3/s) and the combined 

intake capacity for the private ‘auwai near an altitude of 560 ft, 

Waihe‘e Ditch, and the Reservoir 6 diversion also is 1.66 Mgal/d 

(2.56 ft3/s), then the estimated median flow remains 1.3 Mgal/d 

(2 ft3

/s) near an altitude of 400 ft (fig. 53B). For diversion intake 

capacities that result in a median discharge of 1.3 Mgal/d (2 ft3/s) 

near an altitude of 400 ft, (1) the estimated Q70 discharge near an 

altitude of 400 ft is 0.26 Mgal/d (0.40 ft3

/s) and (2) the estimated 

Q90 discharge near an altitude of 400 ft ranges from zero to 0.16 

Mgal/d (0.25 ft3

/s), depending on the diversion intake capacity of 

the South Side Ditch and combined diversion intake capacity for 

the private ‘auwai near an altitude of 560 ft, Waihe‘e Ditch, and 

the Reservoir 6 diversion (fig. 53B).

0 10 15 5 20 25

0 5 10 15 20 25 0 5 10 15 20 25 0 5 10 15 20 25

30 35 40 0 10 15 5 20 25 30 35 40 0 10 15 5 20

Q50 Q70 Q90

Q50 Q70 Q90

25 30 35 40

0

5

10

15

20

25

0

5

10

15

20

25

30

35

40

0

5

10

15

20

25

0

5

10

15

20

25

30

35

40

CAPACITY OF COMMON INTAKE FOR ÿÏAO-MÄNIANIA AND ÿÏAO-WAIKAPÜ DITCHES, ÿÏAO STREAM, IN CUBIC FEET PER SECOND

CAPACITY OF COMMON INTAKE FOR ÿÏAO-MÄNIANIA AND ÿÏAO-WAIKAPÜ DITCHES, ÿÏAO STREAM, IN MILLION GALLONS PER DAY

CAPCITY OF SPRECKELS DITCH INTAKE, ÿÏAO STREAM, IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE, ÿÏAO STREAM, IN MILLION GALLONS PER DAY

A

B

0

24

28

20

16

12

4

8

0

24

28

20

16

12

4

8

0

12

16

4

8

0

12

16

4

8

4

0

8

4

0

8

LINE OF EQUAL ESTIMATED 

DISCHARGE FOR ÿÏAO STREAM 

NEAR AN ALTITUDE OF 35 FEET, 

IN CUBIC FEET PER SECOND--

Interval 2 cubic feet per second

4

Figure 52. Estimated discharges (Q50, Q70, and Q90) in ÿĪao Stream near an altitude of 35 feet, Maui, Hawaiÿi, resulting 

from diversions into the ÿĪao-Mäniania and ÿĪao-Waikapü Ditches and Spreckels Ditch with indicated hypothetical intake 

capacites. A, Zero diversion into a private ÿauwai (ditch) near an altitude of 650 feet. B, Diversion capacity of 0.65 million 

gallons per day (1 cubic foot per second) for a private ÿauwai near an altitude of 650 feet. The Q50, Q70, and Q90 discharges 

represent the discharges that are equaled or exceeded 50, 70, and 90 percent of the time, respectively. A ditch intake is 

assumed to divert at a rate up to, but not exceeding, the indicated capacity (if streamflow is less than the indicated capacity, then all streamflow at the ditch intake is assumed to be diverted).

86 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Ditch-Flow Relations

The flow characteristics for a ditch system are dependent 

on the streamflow characteristics immediately upstream of the 

diversion intake, as well as on the diversion intake capacity. For 

this study, diversions are assumed to be capable of diverting water 

at a rate up to, but not exceeding, the diversion intake capacity. 

If streamflow immediately upstream of an intake is less than or 

equal to the intake capacity, all available streamflow is assumed 

to be diverted. For the purposes of this study, none of the diverted 

water is assumed to return to the stream and the intake capacity of 

a diversion is assumed to be unaffected by water, possibly derived 

from another stream, already in the ditch system.

Waiheÿe River

The Waihe‘e Ditch is the uppermost surface-water 

diversion on Waihe‘e River. Estimated duration discharges for 

the Waihe‘e Ditch are equal to the diversion intake capacity, 

but do not exceed the corresponding duration discharges for 

Waihe‘e River immediately upstream of the intake (fig. 54A). 

For example, the median (Q50) discharge for the Waihe‘e Ditch 

increases linearly, at a one-to-one slope, as the intake capacity 

is assumed to increase (fig. 54A). However, the median 

discharge for Waihe‘e Ditch is limited by the median discharge 

in Waihe‘e River immediately upstream of the diversion 

intake. If the diversion intake capacity equals or exceeds the 

0 2 4

0 1 2 3 4 65 0 1 2 3 4 5 6 0 1 2 3 4 65

6 8 10 0 2 4 6 8 10 0 2 4 6 8

Q50 Q70 Q90

Q50 Q70 Q90

10

0

2

4

0

1

2

3

4

6

5

6

8

10

0

2

4

0

1

2

3

4

6

5

6

8

10

A

B

2

3

4

5

6

1

1

0

0

0

0

0

0

2

3

4

5

6

7

1

2

5

3

4

1

4

2

3

1

3

2

1

2

3

4

CAPACITY OF SOUTH SIDE DITCH INTAKE, WAIKAPÜ STREAM, IN CUBIC FEET PER SECOND

CAPACITY OF SOUTH SIDE DITCH INTAKE, WAIKAPÜ STREAM, IN MILLION GALLONS PER DAY

COMBINED CAPACITY OF PRIVATE ÿAUWAI, WAIHEÿE DITCH, AND RESERVOIR 6 INTAKES,

WAIKAPÜ STREAM, IN CUBIC FEET PER SECOND

COMBINED CAPACITY OF PRIVATE ÿAUWAI, WAIHEÿE DITCH, AND RESERVOIR 6 INTAKES,

WAIKAPÜ STREAM, IN MILLION GALLONS PER DAY

LINE OF EQUAL ESTIMATED 

DISCHARGE FOR WAIKAPÜ STREAM 

NEAR AN ALTITUDE OF 400 FEET, 

IN CUBIC FEET PER SECOND--

Interval 1 cubic foot per second

1

Figure 53. Estimated discharges (Q50, Q70, and Q90) in Waikapu ̄ Stream near an altitude of 400 feet, Maui, Hawaiÿi, resulting from diversion into the South Side Ditch and combined diversions into a private ÿauwai (ditch) near an altitude of 560 

feet, Waiheÿe Ditch, and Reservoir 6 Ditch with indicated hypothetical intake capacities. A, Zero diversion into Everett 

Ditch. B, Diversion capacity of 0.65 million gallons per day (1 cubic foot per second) for Everett Ditch. The Q50, Q70, and Q90

discharges represent the discharges that are equaled or exceeded 50, 70, and 90 percent of the time, respectively. A ditch 

intake is assumed to divert at a rate up to, but not exceeding, the indicated capacity (if streamflow is less than the indicated capacity, then all streamflow at the ditch intake is assumed to be diverted).

Ditch-Flow Relations 87
median discharge in Waihe‘e River immediately upstream 

of the intake (34 Mgal/d; 52 ft3/s), the median discharge for 

Waihe‘e Ditch is equal to the median discharge in Waihe‘e 

River (34 Mgal/d; 52 ft3/s). Similar relations among diversion 

intake capacity, streamflow characteristics, and ditch-flow 

characteristics exist for other duration discharges, including 

the Q70 and Q90 discharges (fig. 54A). 

The Spreckels Ditch is downstream of the Waihe‘e Ditch. 

Thus, water available for diversion by the Spreckels Ditch 

is dependent not only on the diversion intake capacity of 

Spreckels Ditch, but also on the characteristics of the upstream 

diversion and streamflow gains in the intervening reach. A 

family of curves, with each curve corresponding to a particular 

flow in Spreckels Ditch, was developed to show the relation 

between diversion intake capacities and selected duration 

discharges (Q50, Q70, and Q90) for Spreckels Ditch (fig. 54B). 

Combinations of diversion intake capacities that result 

in a specified flow in Spreckels Ditch can be estimated using 

the family of curves (fig. 54B). For example, to maintain a 

median flow of 2.6 Mgal/d (4 ft3/s) in Spreckels Ditch, different 

combinations of diversion intake capacities for Waihe‘e and 

Spreckels Ditches are possible (see fig. 54B, Q50). If the intake 

capacity for the Waihe‘e Ditch is less than 32 Mgal/d (49 ft3/s) 

and the intake capacity of Spreckels Ditch is 2.6 Mgal/d (4.0 

ft3/s), then the estimated median flow in Spreckels Ditch is 2.6 

Mgal/d (4.0 ft3/s). If the intake capacity for the Waihe‘e Ditch is 

equal to 32 Mgal/d (49 ft3/s) and the intake capacity of Spreckels 

Ditch is greater than 2.6 Mgal/d (4.0 ft3/s), then the estimated 

median flow in Spreckels Ditch also is 2.6 Mgal/d (4.0 ft3/s).

If the diversion intake capacity for Waihe‘e Ditch exceeds 

the flow in Waihe‘e River immediately upstream of the intake, 

then the available flow for Spreckels Ditch is limited to the 

gain and tributary inflows that occur in the reach between the 

two diversions. The curves (fig. 54B) change from horizontal 

to vertical lines at a point at which zero flow is expected 

to occur immediately downstream of the Spreckels Ditch 

0 10 20 30 40 50

0 10 15 5 20 25 30 35 0 10 15 5 20 25 30 35 0 10 15 5 20 25 30 35

60 0 10 20 30 40 50 60 0 10 20 30 40

Q50 Q70 Q90

Q50 Q70 Q90

50 60

0

10

20

0

5

10

15

20

25

35

30

30

40

50

60

0

10

20

0

5

10

15

20

25

30

35

30

50

40

60

CAPACITY OF WAIHEÿE DITCH INTAKES, WAIHEÿE RIVER, IN CUBIC FEET PER SECOND

CAPACITY OF WAIHEÿE DITCH INTAKES, WAIHEÿE RIVER, IN MILLION GALLONS PER DAY

CAPACITY OF SPRECKELS DITCH INTAKE,

WAIHEÿE RIVER, IN CUBIC FEET PER SECOND

DISCHARGE INTO WAIHEÿE DITCH,

WAIHEÿE RIVER, IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE,

WAIHEÿE RIVER, IN MILLION GALLONS PER DAY

DISCHARGE INTO WAIHEÿE DITCH,

WAIHEÿE RIVER, IN MILLION GALLONS PER DAY

A

B

40302010

2

40302010

2

302010

2

LINE OF EQUAL ESTIMATED DISCHARGE FOR SPRECKELS DITCH, IN CUBIC FEET PERSECOND--Interval 2 cubic feet per second

10

Figure 54. Estimated diversion discharges (Q50, Q70, and Q90) for the Waiheÿe Ditch and Spreckels Ditch, Waiheÿe River, 

Maui, Hawaiÿi, for indicated intake capacities. A, Waiheÿe Ditch. B, Spreckels Ditch. The Q50, Q70, and Q90 discharges 

represent the discharges that are equaled or exceeded 50, 70, and 90 percent of the time, respectively. A ditch intake is 

assumed to divert at a rate up to, but not exceeding, the indicated capacity (if streamflow is less than the indicated capacity, then all streamflow at the ditch intake is assumed to be diverted).

88 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
diversion intake (ignoring any subsurface leakage immediately 

downstream of the Spreckels Ditch dam that may contribute to 

streamflow downstream of the intake for Spreckels Ditch). 

Waiehu Stream

The North Waiehu Ditch is the only known existing 

surface-water diversion on North Waiehu Stream. Estimated 

duration discharges for the North Waiehu Ditch are equal to the 

diversion intake capacity but do not exceed the corresponding 

duration discharges for North Waiehu Stream immediately 

upstream of the intake (fig. 55A). For example, the median 

(Q50) discharge for the North Waiehu Ditch increases linearly, 

at a one-to-one slope, as the intake capacity increases (fig. 

55A). However, the median discharge for North Waiehu Ditch 

is limited by the median discharge in North Waiehu Stream 

immediately upstream of the diversion intake. If the diversion 

intake capacity equals or exceeds the median discharge in 

North Waiehu Stream immediately upstream of the intake (3.2 

Mgal/d; 4.9 ft3/s) (table 19), the median discharge for North 

Waiehu Ditch is equal to the median discharge in North Waiehu 

Stream (3.2 Mgal/d; 4.9 ft3/s). Similar relations among diversion 

intake capacity, streamflow characteristics, and ditch-flow 

characteristics exist for other duration discharges, including the 

Q70 and Q90 discharges (fig. 55A). 

The Spreckels Ditch is downstream of two private 

‘auwai on South Waiehu Stream. Thus, water diverted by the 

0 1 2 3 4

0 0.5 1.0 1.5 2.0 2.5 3.0 0 0.5 1.0 1.5 2.0 2.5 3.0 0 0.5 1.0 1.5 2.0 2.5 3.0

5 0 1 2 3 4 5 0 1 2 3 4

Q50 Q70 Q90

Q50 Q70 Q90

5

0

1

2

3

4

0

1.0

0.5

1.5

2.0

2.5

3.0

5

0

1

2

3

4

0

1.0

0.5

1.5

2.0

2.5

3.0

5

CAPACITY OF EACH PRIVATE ÿAUWAI INTAKE, SOUTH WAIEHU STREAM, IN CUBIC FEET PER SECOND

0 1 2 3 4 5 0 1 2 3 4 5 0 1 2 3 4 5

CAPACITY OF NORTH WAIEHU DITCH INTAKE, NORTH WAIEHU STREAM, IN CUBIC FEET PER SECOND

CAPACITY OF NORTH WAIEHU DITCH INTAKE, NORTH WAIEHU STREAM, IN MILLION GALLONS PER DAY

0 0.5 1.0 1.5 2.0 2.5 3.0 0 0.5 1.0 1.5 2.0 2.5 3.0 0 0.5 1.0 1.5 2.0 2.5 3.0

CAPACITY OF EACH PRIVATE ÿAUWAI INTAKE, SOUTH WAIEHU STREAM, IN MILLION GALLONS PER DAY

A

B

CAPACITY OF SPRECKELS DITCH INTAKE,

SOUTH WAIEHU STREAM, IN CUBIC FEET PER SECOND

DISCHARGE INTO NORTH WAIEHU DITCH,

NORTH WAIEHU STREAM, IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE,

SOUTH WAIEHU STREAM, IN MILLION GALLONS PER DAY

DISCHARGE INTO NORTH WAIEHU DITCH,

NORTH WAIEHU STREAM, IN MILLION GALLONS PER DAY

0.2

321

0.20.2

1

LINE OF EQUAL ESTIMATED 

DISCHARGE FOR SPRECKELS

DITCH, IN CUBIC FEET PER 

SECOND--Interval 0.2 cubic feet

per second

0.2

Figure 55. Estimated diversion discharges (Q50, Q70, and Q90) for the North Waiehu Ditch, North Waiehu Stream, and 

Spreckels Ditch, South Waiehu Stream, Maui, Hawaiÿi, for indicated intake capacities. A, North Waiehu Ditch. B, Spreckels Ditch. Two private ÿauwai (ditches), near altitudes of 620 and 570 feet, exist upstream of the Spreckels Ditch intake on 

South Waiehu Stream. The Q50, Q70, and Q90 discharges represent the discharges that are equaled or exceeded 50, 70, 

and 90 percent of the time, respectively. A ditch intake is assumed to divert at a rate up to, but not exceeding, the indicated 

capacity (if streamflow is less than the indicated capacity, then all streamflow at the ditch intake is assumed to be diverted).

Ditch-Flow Relations 89
Spreckels Ditch is dependent not only on the diversion intake 

capacity of Spreckels Ditch, but also on the characteristics of 

the upstream diversions. A family of curves, with each curve 

corresponding to a particular flow diverted into Spreckels Ditch 

from South Waiehu Stream, was developed to show the relation 

between diversion intake capacities and selected duration 

discharges (Q50, Q70, and Q90) for Spreckels Ditch (fig. 55B). 

Because South Waiehu Stream loses water in the reach between 

the downstream private ‘auwai and Spreckels Ditch, the 

available flow for Spreckels Ditch is estimated to be zero if the 

capacities of the private ‘auwai exceed the streamflow of South 

Waiehu Stream. The curves (fig. 55B) change from horizontal 

to vertical lines at a point at which zero flow is expected 

to occur immediately downstream of the Spreckels Ditch 

diversion intake (ignoring any subsurface leakage immediately 

downstream of the Spreckels Ditch dam that may contribute to 

streamflow downstream of the intake for Spreckels Ditch).

ÿĪao Stream

The common intake of the ‘Īao-Waikapū and ‘Īao-Māniania 

Ditches is the uppermost surface-water diversion intake on ‘Īao 

Stream. Estimated duration discharges for the ‘Īao-Waikapū and 

‘Īao-Māniania Ditches are equal to the diversion intake capacity 

but do not exceed the corresponding duration discharges for ‘Īao 

Stream immediately upstream of the intake (plot not shown). 

The Spreckels Ditch is downstream of the common intake 

of the ‘Īao-Waikapū and ‘Īao-Māniania Ditches and a private 

‘auwai. Thus, water available for diversion by the Spreckels 

Ditch is dependent on the diversion intake capacity of Spreckels 

Ditch, the characteristics of the upstream diversions, and 

streamflow losses in the intervening reaches. A family of curves, 

with each curve corresponding to a particular flow into Spreckels 

Ditch, was developed to show the relation between diversion 

intake capacities and selected duration discharges (Q50, Q70, and 

0 10 15 5 20 25

0 5 10 15 20 25 0 5 10 15 20 25 0 5 10 15 20 25

30 35 40 0 10 15 5 20 25 30 35 40 0 10 15 5 20

Q50 Q70 Q90

Q50 Q70 Q90

25 30 35 40

0

5

10

15

20

25

0

5

10

15

20

25

30

35

40

0

5

10

15

20

25

0

5

10

15

20

25

30

35

40

CAPACITY OF COMMON INTAKE FOR ÿÏAO-MÄNIANIA AND ÿÏAO-WAIKAPÜ DITCHES, ÿÏAO STREAM, IN CUBIC FEET PER SECOND

CAPACITY OF COMMON INTAKE FOR ÿÏAO-MÄNIANIA AND ÿÏAO-WAIKAPÜ DITCHES, ÿÏAO STREAM, IN MILLION GALLONS PER DAY

CAPACITY OF SPRECKELS DITCH INTAKE, ÿÏAO STREAM, IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE, ÿÏAO STREAM, IN MILLION GALLONS PER DAY

A

B

302010

2

1

1

1

1

2010

2

10

1

Q50

302010

2

2010

2

10

1

LINE OF EQUAL ESTIMATED DISCHARGE FOR SPRECKELSDITCH, ÿÏAO STREAM, IN CUBICFEET PER SECOND--Interval 1 cubic foot per second

2

Figure 56. Estimated diversion discharges (Q50, Q70, and Q90) for the Spreckels Ditch, ÿĪao Stream, Maui, Hawaiÿi, for 

indicated intake capacities. A, Zero diversion into a private ÿauwai (ditch) near an altitude of 650 feet. B, Diversion of 0.65 

million gallons per day (1 cubic foot per second) into a private ÿauwai near an altitude of 650 feet. The Q50, Q70, and Q90

discharges represent the discharges that are equaled or exceeded 50, 70, and 90 percent of the time, respectively. A ditch 

intake is assumed to divert at a rate up to, but not exceeding, the indicated capacity (if streamflow is less than the indicated 

capacity, then all streamflow at the ditch intake is assumed to be diverted).

90 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Q90) for Spreckels Ditch (fig. 56). The curves (fig. 56) change 

from horizontal to vertical lines at a point at which zero flow 

is expected to occur immediately downstream of the Spreckels 

Ditch diversion intake (ignoring any leakage that may contribute 

to streamflow downstream of Spreckels Ditch). The diversion 

intake capacity for the existing private ‘auwai is unknown but 

much less than the current diversion intake capacities for the ‘ĪaoWaikapū and ‘Īao-Māniania Ditches and Spreckels Ditch. For 

this study, the intake capacity of the private ‘auwai was assumed 

to be either 0 (fig. 56A) or 0.65 Mgal/d (1 ft3/s) (fig. 56B), which 

covers the range of available measured diversion rates. 

Waikapu ̄ Stream

The South Side Ditch is the uppermost surface-water 

diversion intake on Waikapū Stream. Estimated duration 

discharges for the South Side Ditch are equal to the diversion 

intake capacity but do not exceed the corresponding duration 

discharges for Waikapū Stream immediately upstream of the 

intake (plot not shown). 

The diversion intakes for the private ‘auwai near 

an altitude of 560 ft, Waihe‘e Ditch, and the Reservoir 6 

diversion are downstream of the diversion intakes for the 

South Side and Everett Ditches. Thus, water available 

for diversion by the private ‘auwai, Waihe‘e Ditch, and 

the Reservoir 6 diversion is dependent not only on the 

diversion intake capacities of these systems, but also on the 

characteristics of the upstream diversions and streamflow 

losses in the intervening reaches. A family of curves, with 

each curve corresponding to a particular combined flow 

into the private ‘auwai near an altitude of 560 ft, Waihe‘e 

Ditch, and the Reservoir 6 diversion, was developed to 

show the relation between diversion intake capacities and 

selected duration discharges (Q50, Q70, and Q90) for these 

diversions (fig. 57). The curves (fig. 57) change from 

horizontal to vertical lines at a point at which zero flow is 

expected to occur immediately downstream of the Reservoir 

6 diversion intake (ignoring any leakage that may contribute 

to streamflow downstream of the Reservoir 6 intake). The 

diversion intake capacity of the Everett Ditch is unknown. 

For this study, the intake capacity of Everett Ditch was 

assumed to be either 0 (fig. 57A) or 0.65 Mgal/d (1 ft3

/s) 

(fig. 57B), which covers the range of available measured 

diversion rates. 

Effects of Surface-Water Diversions on 

Recharge

For streams in which all of the dry-weather flow is 

diverted, infiltration of water in losing reaches downstream 

of diversions may be reduced to zero during dry-weather 

conditions. Dry stream reaches of varying lengths were 

observed in each of the Nā Wai ‘Ehā streams downstream 

of existing diversions during the 2006–2008 data-collection 

period. For natural, undiverted conditions, many of these 

same stream reaches would not be dry. Thus, these dry stream 

reaches created by diversions represent a potential loss of 

recharge to the underlying groundwater body. The loss of 

recharge immediately beneath diverted streams is offset to 

some extent by enhanced recharge associated with ditch 

transmission losses and reservoir seepage (Broadbent, 1988) 

or irrigation return flow (Engott and Vana, 2007), although 

the location where the recharge takes place will change. The 

effects of recharge distribution on the groundwater system 

can be evaluated using a numerical groundwater model that 

accounts for the spatial distribution of groundwater recharge 

(Gingerich, 2008). 

The amount of recharge that takes place along losing 

stream reaches is dependent on a number of factors, including 

(1) the amount of flow available in the stream (the loss may 

be limited by the upstream flow), (2) the antecedent moisture 

of the channel sediments (dry antecedent conditions may 

be associated with high infiltration rates during the early 

period when a stream first begins to flow), (3) channel slope, 

geometry, and wetted perimeter, (4) the presence of a poorly 

permeable streambed-clogging layer of fine sedimentary 

materials or biofilm growth, which can be modified during 

periods of high flow, (5) the hydraulic properties of the 

sediments beneath and near the streambed, and (6) the 

presence of a shallow groundwater body near the stream 

(Sophocleous, 2002; Vázquez-Suñé and others, 2007). These 

factors may contribute to variability in measured gains or 

losses within a stream reach. Because the existing diversions 

have a reduced effect on potential groundwater recharge 

during periods of high flow, the effects of diversions on 

recharge are considered only for low-flow conditions. 

The seepage-run measurements were used to develop 

relations between upstream and downstream flows of 

selected reaches in each stream (see section on “Seepage-Run 

Measurements” and figs. 32–39), and these relations were used 

to estimate the effects of surface-water diversions on recharge 

beneath the stream channels during low-flow conditions. 

The effects of the diversions on recharge were determined 

at selected upstream flows equal to and less than the median 

flow (Q50, Q55, Q60, Q65, Q70, Q75, Q80, Q85, Q90, Q95, and Q99). 

The reductions in recharge were integrated to provide an 

overall estimate of the reduction in recharge during low-flow 

conditions. At each duration discharge, the recharge reduction 

was weighted by the percentage of time that flow occurs 

during low-flow conditions. The overall percentage of time 

that each selected flow occurs was determined to be half of the 

difference between duration percentiles of adjacent duration 

discharges. For example, the overall percentage of time that 

the Q55 flow was assumed to occur was equal to (60-50)/2, or 

5 percent. Similarly, the overall percentage of time that the 

Q50 flow was assumed to occur was equal to (55-50)/2, or 2.5 

percent. For this study, reductions in recharge were computed 

only for low-flow conditions and, thus, the overall percentage 

Effects of Surface-Water Diversions on Recharge 91
of time that each flow was assumed to occur was doubled. 

During low-flow conditions, when flow is less than the median 

flow, the Q50 flow occurs 5 (=2.5×2) percent of the time. Thus, 

for the Q50 flow, the recharge reduction was multiplied by 0.05 

(equal to 5 percent of the time during low-flow conditions); for 

the Q55 to Q90 flows, the recharge reductions were multiplied 

by 0.1; for the Q95 flow, the recharge reduction was multiplied 

by 0.09; and for the Q99 flow, the recharge reduction was 

multiplied by 0.06. The sum of the weights is equal to 1, 

reflecting 100 percent of the time during low-flow conditions.

 Diversion of surface water from a stream reduces the 

amount of water available for infiltration and recharge beneath 

the stream channel. Thus, as the capacity of the diversion 

intakes increase, the reduction in potential recharge generally 

increases. At some level of diversion intake capacity, the reach 

immediately downstream of the diversion may have zero flow, 

the effects of diversions on recharge reduction may reach a 

maximum value, and increased diversion intake capacity has 

no further effect on reducing recharge. The reported recharge 

reductions represent average values over periods when the 

upstream, undiverted flows are less than or equal to the 

median flow, which occurs 50 percent of the time. Also, for 

the purposes of this analysis, none of the diverted water is 

assumed to return to the stream and no leakage immediately 

downstream of diversion structures is assumed to contribute to 

streamflow.

Waiheÿe River

For natural, undiverted low-flow conditions, the 

estimated seepage loss from Waihe‘e River downstream of 

the intakes for the Waihe‘e Ditch is about 1.7 Mgal/d (2.7 

ft3/s). This seepage loss takes place entirely downstream of 

an altitude of 400 ft and represents potential groundwater 

recharge. The effects of diversions on recharge beneath 

0 2 4

0 1 2 3 4 65 0 1 2 3 4 5 6 0 1 2 3 4 65

6 8 10 0 2 4 6 8 10 0 2 4 6 8

Q50 Q70 Q90

Q50 Q70 Q90

10

0

2

4

0

1

2

3

4

6

5

6

8

10

0

2

4

0

1

2

3

4

6

5

6

8

10

A

B

CAPACITY OF SOUTH SIDE DITCH INTAKE, WAIKAPÜ STREAM, IN CUBIC FEET PER SECOND

CAPACITY OF SOUTH SIDE DITCH INTAKE, WAIKAPÜ STREAM, IN MILLION GALLONS PER DAY

COMBINED CAPACITY OF PRIVATE ÿAUWAI, WAIHEÿE DITCH, AND RESERVOIR 6 INTAKES,

WAIKAPÜ STREAM, IN CUBIC FEET PER SECOND

COMBINED CAPACITY OF PRIVATE ÿAUWAI, WAIHEÿE DITCH, AND RESERVOIR 6 INTAKES,

WAIKAPÜ STREAM, IN MILLION GALLONS PER DAY

7

6543265432432

65432154321321

1 1 1 LINE OF EQUAL ESTIMATED COMBINED DISCHARGE FOR PRIVATE ÿAUWAI, WAIHEÿE DITCH, AND RESERVOIR 6 DITCH, WAIKAPÜ STREAM, IN CUBIC FEET PER SECOND-- Interval 1 cubic foot per second

1

Figure 57. Estimated combined diversion discharges (Q50, Q70, and Q90) for a private ÿauwai (ditch) near an altitude of 560 

feet, Waiheÿe Ditch, and Reservoir 6 Ditch, Waikapü Stream, Maui, Hawaiÿi, for indicated intake capacities. A, Zero diversion into Everett Ditch. B, Diversion capacity of 0.65 million gallons per day (1 cubic foot per second) for Everett Ditch. The 

Q50, Q70, and Q90 discharges represent the discharges that are equaled or exceeded 50, 70, and 90 percent of the time, 

respectively. A ditch intake is assumed to divert at a rate up to, but not exceeding, the indicated capacity (if streamflow is 

less than the indicated capacity, then all streamflow at the ditch intake is assumed to be diverted).

92 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Waihe‘e River were evaluated for diversion intake capacities 

of 0 to 39 Mgal/d (0 to 60 ft3/s) for the Waihe‘e Ditch; 0 to 

39 Mgal/d (0 to 60 ft3/s) for Spreckels Ditch; and 0 or 3.2 

Mgal/d (0 or 5 ft3/s) for the Field 1 intake (fig. 58). The intake 

capacity for the Field 1 diversion is unknown and, thus, the 

use of 3.2 Mgal/d (5 ft3/s) for the intake capacity of the Field 

1 intake is arbitrary. The family of curves (fig. 58), with each 

curve corresponding to a selected value of groundwaterrecharge reduction, shows the relation between capacities of 

the diversion intakes and recharge reduction. For the diversion 

intake capacities tested, the maximum overall reduction in 

recharge is 1.7 Mgal/d (2.7 ft3/s) for different combinations of 

diversion intake capacities (fig. 58). The reduction in recharge 

represents the average value during low-flow conditions 

when the upstream, undiverted streamflow is less than the 

median flow. For combinations of diversion intake capacities 

up to about 17 Mgal/d (26 ft3/s), the overall reduction in 

recharge may be zero (fig. 58). Overall reduction in recharge 

may be zero if available streamflow in reaches downstream 

of diversions exceeds maximum loss rates (and losses are 

assumed to be independent of streamflow). 

Using the approximate diversion capacity settings of 

40 Mgal/d (62 ft3/s) for the Waihe‘e Ditch and 12 Mgal/d 

(18 ft3/s) for Spreckels Ditch (Suzuki, 2007), and either 0 or 

3.2 Mgal/d (0 or 5 ft3/s) for the Field 1 intake, the estimated 

overall reduction in recharge is 1.7 Mgal/d (2.7 ft3/s) (fig. 

58). This reduction in recharge corresponds to the maximum 

estimated value. The reduction in recharge takes place 

downstream of the intake for Spreckels Ditch. 

Waiehu Stream

For natural, undiverted low-flow conditions, the 

estimated seepage loss (potential groundwater recharge) 

from North Waiehu, South Waiehu, and Waiehu Streams 

downstream of an altitude of about 880 ft is about 2.9 Mgal/d 

(4.5 ft3/s). About 83 percent of the seepage loss takes place 

upstream of an altitude of 280 ft, and the remaining 17 percent 

takes place downstream of an altitude of 190 ft. 

To estimate the reduction in recharge caused by 

diversions from North and South Waiehu Streams, natural 

flows (upstream of all diversions) in each stream at common 

flow-duration percentiles were assumed to occur concurrently. 

The effects of diversions on recharge were evaluated for the 

following diversion intake capacities: 0 to 3.2 Mgal/d (0 to 

5 ft3

/s) for North Waiehu Ditch, North Waiehu Stream; 0 to 

3.2 Mgal/d (0 to 5 ft3/s) for Spreckels Ditch, South Waiehu 

Stream; and 0 or 0.32 Mgal/d (0 or 0.5 ft3/s) each for two 

existing private ‘auwai with intakes near altitudes of 620 and 

570 ft, South Waiehu Stream. The diversion intake capacities 

for the two existing private ‘auwai are unknown and variable, 

depending on the condition of the intakes. For this study, 

the intake capacity of each private ‘auwai was assumed to 

be either 0 (fig. 59A) or 0.32 Mgal/d (0.5 ft3

/s) (fig. 59B), 

which generally represents the range of available measured 

diversion rates. The family of curves (fig. 59), with each curve 

corresponding to a selected value of groundwater-recharge 

reduction, shows the relation between capacities of the 

diversion intakes and recharge reduction. For the diversion 

intake capacities tested, the maximum overall reduction in 

recharge is 1.9 Mgal/d (3.0 ft3

/s) (fig. 59). 

Using the reported diversion capacity of North Waiehu 

Ditch of 1.5 Mgal/d (2.3 ft3/s) (Suzuki, 2007) and a diversion 

intake capacity of 1.3 Mgal/d (2.0 ft3

/s) for Spreckels Ditch, 

the overall reduction in recharge during low-flow periods is 

1.0 Mgal/d (1.6 ft3

/s) if no water is diverted by each of the two 

existing private ‘auwai. Using the reported diversion capacity 

of North Waiehu Ditch of 1.5 Mgal/d (2.3 ft3/s) (Suzuki, 

2007) and a diversion intake capacity of 1.3 Mgal/d (2.0 ft3

/s) 

for Spreckels Ditch, the overall reduction in recharge during 

low-flow periods is 1.2 Mgal/d (1.8 ft3

/s) if 0.32 Mgal/d (0.5 

ft3

/s) is diverted by each of the two existing private ‘auwai. 

For these diversion intake capacities, about 70 percent of 

the overall reduction in recharge takes place upstream of an 

altitude of 280 ft. 

ÿĪao Stream

For natural, undiverted low-flow conditions, the 

estimated seepage loss (potential groundwater recharge) 

from ‘Īao Stream downstream of the common intake for the 

‘Īao-Waikapū and ‘Īao-Māniania Ditches is about 5.6 Mgal/d 

(8.7 ft3/s). About 63 percent of the seepage loss takes place 

upstream of an altitude of 360 ft, and the remaining 37 percent 

takes place downstream of an altitude of 220 ft.

The effects of diversions on potential recharge beneath 

‘Īao Stream were evaluated for the following diversion 

intake capacities: 0 to 26 Mgal/d (0 to 40 ft3/s) for the ‘ĪaoWaikapū and ‘Īao-Māniania Ditches; 0 to 26 Mgal/d (0 to 40 

ft3/s) for Spreckels Ditch; and 0 or 0.65 Mgal/d (0 or 1 ft3/s) 

for an existing private ‘auwai with an intake at an altitude of 

about 650 ft (fig. 60). The diversion intake capacity for the 

existing private ‘auwai is unknown but much less than the 

current diversion intake capacities for the ‘Īao-Waikapū and 

‘Īao-Māniania Ditches and Spreckels Ditch. For this study, 

the intake capacity of the private ‘auwai was assumed to be 

either 0 (fig. 60A) or 0.65 Mgal/d (1 ft3/s) (fig. 60B), which 

covers the range of available measured diversion rates. The 

family of curves (fig. 60), with each curve corresponding to 

a selected value of groundwater-recharge reduction, shows 

the relation between capacities of the diversion intakes 

and recharge reduction. For the diversion intake capacities 

tested, the maximum overall reduction in recharge is 5.3 

Mgal/d (8.2 ft3

/s) for different combinations of diversion 

intake capacities (fig. 60). For combinations of diversion 

intake capacities up to about 3.2 Mgal/d (5 ft3/s), the overall 

reduction in recharge may be zero (fig. 60). Overall reduction 

in recharge may be zero if available streamflow in reaches 

Effects of Surface-Water Diversions on Recharge 93
0.32 (0.5)

0

0.65 (1.0)

0.97 (1.5)

1.3 (2.0)

1.6 (2.5)

1.7 (2.7)

0.32 (0.5)

0

0.65 (1.0)

0.97 (1.5)

1.3 (2.0)

1.6 (2.5)

1.7 (2.7)

LINE OF EQUAL ESTIMATED RECHARGE REDUCTION IN WAIHEÿE RIVER, 

IN MILLION GALLONS PER DAY REDUCTION RELATIVE TO UNDIVERTED 

LOW-FLOW CONDITIONS-- Interval is variable. Value in parentheses

is in cubic feet per second.

0.65 (1.0)

0 10 20 30

CAPACITY OF WAIHEÿE DITCH INTAKES, WAIHEÿE RIVER, IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE, WAIHEÿE RIVER, IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE, WAIHEÿE RIVER, IN MILLION GALLONS PER DAY

40 50 60

0 5 10 15

CAPACITY OF WAIHEÿE DITCH INTAKES, WAIHEÿE RIVER, IN MILLION GALLONS PER DAY

20 25 30 35

0

10

20

30

40

50

60

0

5

10

15

20

25

30

35

0

5

10

15

20

25

30

35

0

10

20

30

40

50

60

A

B

Figure 58. Reduction in potential groundwater recharge, relative to undiverted conditions, caused by 

diversions into the Waiheÿe Ditch and Spreckels Ditch with indicated intake capacities, Waiheÿe River, 

Maui, Hawaiÿi. A, Zero diversion into the Field 1 intake. B, Diversion capacity of 3.2 million gallons per 

day (5 cubic feet per second) for the Field 1 intake. Recharge reduction computed for low-flow periods, 

when streamflow is less than or equal to the median discharge. A ditch intake is assumed to divert at 

a rate up to, but not exceeding, the indicated capacity (if streamflow is less than the indicated capacity, 

then all streamflow at the ditch intake is assumed to be diverted).

94 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
0.32 (0.5)

0.65 (1.0)0.97 (1.5)

1.3 (2.0)1.6 (2.5)1.8 (2.8)

0.32 (0.5)0.65 (1.0)0.97 (1.5)

1.3 (2.0)1.6 (2.5)1.9 (3.0)

LINE OF EQUAL ESTIMATED RECHARGE REDUCTION IN WAIEHU STREAM, 

IN MILLION GALLONS PER DAY REDUCTION RELATIVE TO UNDIVERTED 

LOW-FLOW CONDITIONS-- Interval is variable. Value in parentheses

is in cubic feet per second.

0.65 (1.0)

0.0 0.5 1.0 1.5 2.0 2.5 3.0 4.5

CAPACITY OF NORTH WAIEHU DITCH INTAKE, NORTH WAIEHU STREAM, IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE, SOUTH WAIEHU STREAM, IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE, SOUTH WAIEHU STREAM, IN MILLION GALLONS PER DAY

3.5 4.0 5.0

0 0.5 1.0 1.5

CAPACITY OF NORTH WAIEHU DITCH INTAKE, NORTH WAIEHU STREAM, IN MILLION GALLONS PER DAY

2.0 2.5 3.0

0.0

1.0

0.5

2.0

1.5

2.5

3.5

3.0

4.5

4.0

5.0

0.0

1.0

0.5

2.0

1.5

2.5

3.5

3.0

4.5

4.0

5.0

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0.0

0.5

1.0

1.5

2.0

2.5

A 3.0

B

Figure 59. Reduction in potential groundwater recharge, relative to undiverted conditions, caused by 

diversions into the North Waiehu and Spreckels Ditches with indicated intake capacities, Waiehu Stream, 

Maui, Hawaiÿi. A, Zero diversion into two private ÿauwai (ditches) near altitudes of 620 and 570 feet, South 

Waiehu Stream. B, Combined diversion capacity of 0.65 million gallons per day (1 cubic foot per second) 

for two private ÿauwai near altitudes of 620 and 570 feet, South Waiehu Stream. Recharge reduction computed for low-flow periods, when streamflow is less than or equal to the median discharge. A ditch intake 

is assumed to divert at a rate up to, but not exceeding, the indicated capacity (if streamflow is less than 

the indicated capacity, then all streamflow at the ditch intake is assumed to be diverted).

Effects of Surface-Water Diversions on Recharge 95
Figure 60. Reduction in potential groundwater recharge, relative to undiverted conditions, caused by 

diversions into the ÿÏao-Ma ̄niania and ÿÏao-Waikapu ̄ Ditches and Spreckels Ditch with indicated intake 

capacities, ÿÏao Stream, Maui, Hawaiÿi. A, Zero diversion into a private ÿauwai (ditch) near an altitude 

of 650 feet. B, Diversion capacity of 0.65 million gallons per day (1 cubic foot per second) for a private 

ÿauwai near an altitude of 650 feet. Recharge reduction computed for low-flow periods, when streamflow is less than or equal to the median discharge. A ditch intake is assumed to divert at a rate up to, 

but not exceeding, the indicated capacity (if streamflow is less than the indicated capacity, then all 

streamflow at the ditch intake is assumed to be diverted).

0

0.65 (1)

1.3 (2)

1.9 (3)

2.6 (4)3.2 (5)3.9 (6)4.5 (7)5.2 (8)

5.3 (8.2)

0

0.65 (1)

1.3 (2)

1.9 (3)

2.6 (4)3.2 (5)3.9 (6)4.5 (7)5.2 (8)

5.3 (8.2)

LINE OF EQUAL ESTIMATED RECHARGE REDUCTION IN ÿÏAO STREAM, 

IN MILLION GALLONS PER DAY REDUCTION RELATIVE TO UNDIVERTED 

LOW-FLOW CONDITIONS-- Interval is variable. Value in parentheses

is in cubic feet per second.

0.65 (1)

0 5 10 15 20 25 30

CAPACITY OF COMMON INTAKE FOR ÿÏAO-MÄNIANIA AND ÿÏAO-WAIKAPÜ DITCHES, ÿÏAO STREAM, 

IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE, ÿÏAO STREAM, IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE, ÿÏAO STREAM, IN MILLION GALLONS PER DAY

35 40

0 5 10 15

CAPACITY OF COMMON INTAKE FOR ÿÏAO-MÄNIANIA AND ÿÏAO-WAIKAPÜ DITCHES, ÿÏAO STREAM, 

IN MILLION GALLONS PER DAY

20 25

0

10

5

20

15

25

35

30

40

0

10

5

20

15

25

35

30

40

0

5

10

15

20

25

0

5

10

15

20

A 25

B

96 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
downstream of diversions exceeds maximum loss rates (and 

losses are assumed to be independent of streamflow).

Using the reported diversion capacity of the ‘ĪaoWaikapū and ‘Īao-Māniania Ditches of 20 Mgal/d (31 ft3

/s) 

(Suzuki, 2007) and a diversion intake capacity of at least 3.9 

Mgal/d (6 ft3/s) for Spreckels Ditch, the overall reduction 

in recharge is 4.8 Mgal/d (7.4 ft3/s) if no water is diverted 

by the existing private ‘auwai. For these diversion intake 

capacities, about 55 percent of the overall reduction in 

recharge takes place upstream of an altitude of 360 ft. 

Waikapu  ̄ Stream

For natural, undiverted low-flow conditions, the estimated 

seepage loss (potential groundwater recharge) from Waikapū 

Stream downstream of the intake for the South Side Ditch is 

about 4.3 Mgal/d (6.7 ft3/s). About 8 percent of the seepage loss 

takes place upstream of an altitude of 400 ft, and the remaining 

92 percent takes place downstream of an altitude of 400 ft.

The effects of diversions on recharge beneath Waikapū 

Stream were evaluated for the following diversion intake 

capacities: 0 to 6.5 Mgal/d (0 to 10 ft3/s) for the South Side 

Ditch; 0 to 6.5 Mgal/d (0 to 10 ft3/s) for the combined capacity 

of a private ‘auwai with an intake near an altitude of 560 ft, 

Waihe‘e Ditch, and the Reservoir 6 diversion; and 0 or 0.65 

Mgal/d (0 or 1 ft3/s) for Everett Ditch. The diversion intake 

capacity of the Everett Ditch is unknown. For this study, the 

intake capacity of Everett Ditch was assumed to be either 0 (fig. 

61A) or 0.65 Mgal/d (1 ft3/s) (fig. 61B), which covers the range 

of available measured diversion rates. The family of curves 

(fig. 61), with each curve corresponding to a selected value of 

groundwater-recharge reduction, shows the relation between 

capacities of the diversion intakes and recharge reduction. For 

the diversion intake capacities tested, the maximum overall 

reduction in recharge is 4.0 Mgal/d (6.2 ft3/s) for different 

combinations of diversion intake capacities (fig. 61). 

Using the approximate diversion capacity of the South 

Side Ditch of 3 Mgal/d (4.6 ft3/s) (Suzuki, 2007) and a 

combined diversion intake capacity of at least 2.3 Mgal/d (3.6 

ft3

/s) for the private ‘auwai, Waihe‘e Ditch, and the Reservoir 

6 diversion, the overall reduction in recharge is 4.0 Mgal/d (6.2 

ft3/s) for diversion intake capacities of 0 or 0.65 Mgal/d (0 or 

1 ft3/s) for Everett Ditch (fig. 61). For these diversion intake 

capacities, the overall reduction in recharge takes place entirely 

downstream of an altitude of 400 ft. 

Effects of Surface-Water Diversions on 

Physical Habitat

Changes in streamflow may affect the quantity and 

quality of physical habitat used by native stream fauna (see, 

for example, Gingerich and Wolff, 2005; Oki and others, 

2006). This section addresses the effects that streamflow 

reduction, caused by diverting water, will have on physical 

habitat in Waihe‘e River and Waiehu, ‘Īao, and Waikapū 

Streams. Groundwater withdrawals that affect streamflow 

also can affect physical habitat used by the native fauna. 

However, determination of the effects of groundwater 

withdrawal on physical habitat used by the native fauna is 

beyond the scope of this study.

The Instream Flow Incremental Methodology (IFIM) 

is a tool used to quantify the effects of incremental changes 

in streamflow, and was developed to assess instream flow 

issues and assist in water-management decisions (Bovee, 

1982). The development of many small hydropower projects 

and expanding urban development encroaching on river and 

stream systems in the United States during the 1970s and 

1980s led to the design and refinement of tools that evaluate 

instream-habitat quality and predict how the populations and 

communities of fish inhabiting the streams and rivers would be 

affected.

A number of these tools are referred to as habitatselection models, preference models, or habitat-index 

models. The Physical Habitat Simulation System 

(PHABSIM) (Bovee, 1986, 1997; Bovee and others, 1998) is 

an example of a habitat-selection model for stream organisms 

and has been used in many studies to assist in management 

decisions (Railsback and others, 2003). In Hawai‘i, 

Gingerich and Wolff (2005) and Oki and others (2006) used 

PHABSIM to evaluate the effects of surface-water diversions 

on physical habitat. 

Habitat-selection modeling combines elements of 

biology and hydrology that may be related to the population 

of an aquatic species. In terms of biology, these models 

commonly account for the frequency of microhabitat 

utilization of a target species. This is often compared with a 

measurement of microhabitat availability to define preference 

or habitat-suitability criteria. The preferred microhabitat 

is assumed to be the most advantageous for a specific 

activity and life stage of the target species. In terms of 

hydrology, these models commonly account for streamflow 

characteristics and stream geomorphology. Computer models 

like PHABSIM are used to merge these components to 

estimate the changes in the quantity of preferred microhabitat 

area available for the target species with incremental changes 

in streamflow.

For this study, the effects of changes in streamflow 

on physical habitat were evaluated using the PHABSIM 

approach. Measurements of microhabitat under different flow 

conditions were combined with habitat-suitability criteria 

modified from those developed for streams in northeast Maui 

(Gingerich and Wolff, 2005). Habitat-suitability criteria 

developed for northeast Maui streams are transferable, in 

some cases, to other areas of the State (Gingerich and Wolff, 

2005). Habitat-suitability criteria specific to the Nā Wai 

‘Ehā area were not developed for this study because existing 

populations of native species within the study reaches were 

considered too small for development of site-specific criteria.

Effects of Surface-Water Diversions on Physical Habitat 97
0.65 (1)

1.3 (2)

1.9 (3)

2.6 (4)

3.2 (5)

3.9 (6)

4.0 (6.2)

1.3 (2)

1.9 (3)

2.6 (4)

3.2 (5)

3.9 (6)

4.0 (6.2)

LINE OF EQUAL ESTIMATED RECHARGE REDUCTION IN WAIKAPÜ STREAM,

IN MILLION GALLONS PER DAY REDUCTION RELATIVE TO UNDIVERTED 

LOW-FLOW CONDITIONS-- Interval is variable. Value in parentheses

is in cubic feet per second.

0.65 (1)

0 1 2 3 4 5

CAPACITY OF SOUTH SIDE DITCH INTAKE, WAIKAPÜ STREAM, IN CUBIC FEET PER SECOND

COMBINED CAPACITY OF PRIVATE ÿAUWAI, WAIHEÿE DITCH, AND RESERVOIR 6 INTAKES, WAIKAPÜ STREAM, IN CUBIC FEET PER SECOND

COMBINED CAPACITY OF PRIVATE ÿAUWAI, WAIHEÿE DITCH, AND RESERVOIR 6 INTAKES, WAIKAPÜ STREAM, IN MILLION GALLONS PER DAY

6 7 8 9 10

0 1 2 3

CAPACITY OF SOUTH SIDE DITCH INTAKE, WAIKAPÜ STREAM, IN MILLION GALLONS PER DAY

4 5 6

0

2

1

3

4

5

6

7

9

8

10

0

1

2

3

4

5

6

0

1

2

3

4

5

6

0

1

2

3

4

5

7

6

8

9

10

A

B

Figure 61. Reduction in potential groundwater recharge, relative to undiverted conditions, caused by 

diversion into the South Side Ditch and combined diversions into a private ÿauwai (ditch) near an altitude 

of 560 feet, Waiheÿe Ditch, and Reservoir 6 Ditch with indicated intake capacities, Waikapu ̄ Stream, 

Maui, Hawaiÿi. A, Zero diversion into Everett Ditch. B, Diversion capacity of 0.65 million gallons per day 

(1 cubic foot per second) for Everett Ditch. Recharge reduction computed for low-flow periods, when 

streamflow is less than or equal to the median discharge. A ditch intake is assumed to divert at a rate 

up to, but not exceeding, the indicated capacity (if streamflow is less than the indicated capacity, then all 

streamflow at the ditch intake is assumed to be diverted).

98 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Stream Habitat Data Collection

Habitat data were collected at two or three reaches in each 

stream (figs. 21–24). Study reaches, each about 300 ft in length, 

were located at stream altitudes ranging from about 30 to 1,140 

ft. In each reach, measurements of microhabitat characteristics 

(depth, velocity, and substrate) generally were made at 10 cross 

sections for at least two different flow conditions.

Study Reaches

Study reaches were selected on the basis of hydrologic, 

ecologic, access, and safety considerations. Because of 

uncertainty related to availability of streamflow, reaches that 

commonly were dry were not selected. The boundaries of 

each 300-ft study reach were selected to exclude tributaries or 

diversions. Reaches immediately upstream and downstream of 

the uppermost diversions were assumed to be comparable in 

terms of habitat characteristics. 

Cross Sections

Cross-section locations within each reach were 

determined using a stratified-random design. Study reaches 

were stratified at the level of three habitat types: riffle, run, 

and pool. Riffles were defined as stream sections with high 

gradient and shallow, fast-moving turbulent water. Runs 

were defined as stream sections with moderate- to fastflowing water with minimal turbulence. Pools were defined 

as low gradient, deeper stream sections with low water 

velocity. Within each reach, the length and location of each 

discrete riffle, run, and pool were determined. The individual 

lengths were summed by habitat type, and the proportion 

of each habitat type within the reach was calculated (table 

22). Ten cross sections were located within each reach. The 

number of cross sections per habitat type was calculated 

on the basis of the proportion of the habitat type within the 

reach. Once it was determined how many cross sections per 

habitat type were to be established, the location of each cross 

section was determined using computer-generated random 

numbers. Brightly colored vinyl flagging tape was labeled 

and placed on the stream bank to mark the location of each 

cross section. At each cross-section location, semipermanent 

boundary markers also were established on each stream 

bank. These semipermanent markers made it possible to 

reestablish cross-section locations throughout the period of 

study. Each cross section was oriented perpendicular to flow 

and stretched across the entire width of the low-flow channel 

of the stream.

For the reach near an altitude of 185 ft in Waiehu Stream, 

10 cross sections originally were defined, but the lowermost 

section became inaccessible during 2008 because of a fallen 

tree. Data from the remaining nine cross sections were used 

in the habitat modeling. For this reach, 50 percent of the total 

length was characterized as riffle habitat. Because one of 

the five riffle sections was not available on all microhabitat 

measurement dates, habitat from the remaining four riffle 

sections was weighted by a factor of 1.25 to reflect the 

percentage of riffle habitat in the reach and to account for the 

missing tenth cross section.

Information on microhabitat availability was recorded 

at each cross section. Each cross section was subdivided into 

rectangular cells 1 ft wide and extending 1 ft downstream 

and 1 ft upstream of a line connecting the ends of the 

section. Thus, each 1-ft-wide cell represents an area of 2 

ft2

. The habitat variables (depth, velocity, and substrate) 

were measured within each individual cell. Water depth was 

determined as the distance between the water surface and 

the stream bottom at the center of the cell. Measured water 

depths ranged from 0 to about 4 ft. In general, velocity was 

determined at the center of the cell at a depth (as measured 

from the water surface) of 0.6 times the total water-column 

depth, although in some cells where depths exceeded 1.5 ft, 

velocity was measured at 0.2 and 0.8 depths. The measurement 

depths were selected because they provide a representation 

of the mean velocity in the vertical water column at a site 

(Rantz and others, 1982). All velocities were measured with 

acoustic-Doppler velocity (ADV) meters. Average velocity 

generally was determined over a 40-second interval, although 

time constraints sometimes dictated a shorter interval of either 

20 or 30 seconds. Measured water velocities ranged from 

zero in pool areas or near stream edges to more than 3 ft/s in 

other areas. The dominant substrate (table 23) was determined 

within each cell, and the percentage of each cell that was not 

completely submerged was recorded where applicable.

Quantification of Suitable Habitat

For this study, suitable physical habitat was quantified 

using the PHABSIM approach (U.S. Geological Survey, 

2001). Habitat-suitability criteria modified from Gingerich and 

Wolff (2005) were used to determine the effects of incremental 

changes in streamflow on physical habitat for selected 

native species. Froude number and depth habitat-suitability 

criteria developed originally for streams in northeast Maui 

(Gingerich and Wolff, 2005) were modified and used for this 

study. The modifications are related to the bin widths used 

for the frequency distributions and the specified minimum 

suitability index. For this study, the bin width for Froude 

number frequency distributions was standardized to 0.05, with 

the first bin range of 0–0.025, and the bin width for depth 

frequency distributions was standardized to 0.20 ft, with the 

first bin range of 0–0.10 ft. The previously applied minimum 

suitability index of 0.20 (Gingerich and Wolff, 2005) was 

not used in this study. Instead, the minimum suitability-index 

values for Froude number and depth were determined from the 

nonparametric tolerance limits.

Effects of Surface-Water Diversions on Physical Habitat 99
Physical habitat for ‘o‘opu ‘alamo‘o and ‘ōpaekala‘ole 

was modeled only at the uppermost reaches in each stream; 

physical habitat for ‘o‘opu nākea was modeled at all 

reaches; physical habitat for ‘o‘opu nōpili was modeled at 

all reaches except the uppermost reaches of Waihe‘e River 

and Waikapū Stream; and physical habitat for hïhïwai 

was modeled only in the two lower reaches of Waihe‘e 

River and the one reach in Waiehu Stream. Physical 

habitat for Eleotris sandwicensis (‘o‘opu ‘akupa) and 

Stenogobius hawaiiensis (‘o‘opu naniha) was not modeled 

because habitat-suitability criteria were neither available 

nor developed in this study, although ‘o‘opu ‘akupa was 

observed in Waihe‘e River. Habitat-suitability criteria for 

hïhïwai developed by Gingerich and Wolff (2005) were 

based on observations during daytime hours, although 

hïhïwai apparently are more active during nighttime hours 

(Brasher, 1997).

The habitat-suitability curves define weights, 

which may range in value from 0 (unusable habitat) to 1 

(preferred habitat), for selected microhabitat parameters. 

For this study, the dominant substrate category (table 23), 

dimensionless Froude number (fig. 62), and depth (fig. 63) 

were used to define microhabitat characteristics within each 

1-ft-wide cell of each cross section. The Froude number 

represents the ratio of inertia force to gravity force and is 

defined as

F = v/(dg)1/2,

where

F is the dimensionless Froude number,

v is the water velocity [L/T],

d is the water depth [L],

g is the acceleration due to gravity [L/T2

],

L represents units of length, and

T represents units of time.

If the Froude number is less than 1, flow is 

characterized as subcritical or tranquil, whereas if the 

Froude number is greater than 1, flow is supercritical, rapid, 

or shooting. A Froude number of 1 indicates critical flow 

(flow at minimum specific energy) (see, for example, Olson, 

1980). Froude numbers computed from velocity and depth 

measurements ranged from 0 in areas with standing water 

to greater than 1 in sections with rapidly flowing water. 

For each 1-ft-wide cell, a composite suitability was 

determined as

Ci

 = Fi×Di×Si,

where

Ci is the composite suitability of cell i,

Fi is the suitability associated with the Froude number 

in cell i, 

Di is the suitability associated with depth in cell i, and

Si is the suitability associated with the dominant 

substrate category in cell i.

The composite-suitability value may range from 0 

(unusable habitat) to 1 (preferred habitat). Because the 

Froude number may be zero for different values of depth, the 

composite suitability included depth to account for different 

habitat suitability for different depths with zero velocity. The 

weighted usable area for a cell (wua), which is a measure of 

suitable physical habitat, is then computed from

wuai = Ai×Ci×Ei,

where

wuai is the weighted usable area of cell i [L2],

Ai is the area of cell i [L2],

Ci is the composite suitability of cell i, and

Ei is the fraction of cell i that is submerged.

For this study, each cell had a total area of 2 ft2. The 

weighted usable area for each cross section was determined 

by adding the weighted-usable-area values for each cell in 

that cross section. Total weighted usable area (WUA) for the 

reach was then determined by summing the weighted-usablearea values for the 10 cross sections, which are representative 

of the reach. Because each 1-ft-wide cell in a cross section 

is 2 ft long, the computed WUA value for a reach with 10 

cross sections is expressed in terms of square feet per 20 ft 

of stream length. By multiplying the WUA for the reach by 

a factor of 50, the WUA also can be expressed in terms of 

square feet per 1,000 ft of stream. Because a stratified-random 

design was used to select cross sections, riffles, runs, and 

100 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄

Table 22. Percentage of riffle, run, and pool habitat within 

studied stream reaches, Maui, Hawaiÿi.

Altitude near downstream 

end of stream reach,

in feet

Percentage of habitat

in 300-foot reach

Riffle Run Pool Total

Waiheÿe River

a

610 43 57 0 100

570 29 71 0 100

405 38 62 0 100

30 53 47 0 100

North Waiehu Stream

a

900 51 49 0 100

820 43 57 0 100

Waiehu Stream

185 47 53 0 100

ÿÏao Stream

a

790 55 45 0 100

730 48 44 8 100

570 42 43 15 100

Waikapü Stream

a

1,140 68 32 0 100

1,050 64 36 0 100

840 68 32 0 100

a

Reach is upstream of uppermost diversion and is assumed to represent comparable 

habitat to the reach immediately downstream.
pools were appropriately weighted according to availability in 

determining the WUA for each reach.

WUA was computed for each study reach at each of 

two to five different measured discharge rates (figs. 64–67). 

At some sites, habitat data were collected over reaches (300 

ft in length) immediately upstream and downstream of a 

diversion to characterize habitat over a range of discharge 

rates. For these cases, habitat data from the upstream reach 

were assumed to be representative of conditions at the 

downstream reach at comparable flows because of the close 

proximity of the upstream and downstream reaches, although 

the percentages of riffles, runs, and pools may have differed 

between the upstream and downstream reaches (table 22). 

This approach was necessitated because reaches immediately 

downstream of diversions generally lacked flows at the higher 

end of the low-flow range (near the median flow). 

In general, data indicate that WUA increases 

monotonically with discharge up to the median natural 

discharge (figs. 64–67). Most studies using PHABSIM 

incorporate hydraulic modeling to estimate depths and 

velocities, and also WUA, for different flow conditions. 

However, hydraulic modeling was not incorporated in this 

study because (1) stream-channel modifications following 

large storms made it too difficult to collect reliable data for 

model calibration and (2) the complexity of the velocity 

distributions in the stream caused by the uneven nature of the 

channel bottoms makes hydraulic modeling results tenuous. 

Thus, for this study, power functions of the form y=axb

 were 

fit to the available data to provide consistent estimates of 

WUA throughout the range of discharges from zero to the 

median natural discharge. A power function monotonically 

increases (or decreases) with increasing values in the 

dependent variable, which is not always the case with a 

quadratic function. Because available data generally indicate 

increasing WUA with discharge within the low-flow range of 

interest (figs. 64–67), fitting the data to a power function was 

considered appropriate. 

The relations between WUA and discharge are steepest 

between discharge rates of zero and a few million gallons 

per day, which indicates that the rate of increase in WUA is 

greatest as discharge increases from zero to a few million 

gallons per day (and the rate of decrease in WUA is greatest 

as discharge decreases from a few million gallons per day to 

zero). WUA values range from zero at no flow to more than 

Table 23. Substrate size categories and dominant substrate suitability values for selected native species 

(Gingerich and Wolff, 2005).

[ >, greater than; in., inches]

Species

Dominant substrate suitability value

Silt and 

organic 

detritus

Sand

(>0.002 to 

0.08 in.)

Gravel

(>0.08 to 

0.8 in.)

Cobble

(>0.8 to

4 in.)

Small

boulder

(>4 to 12 in.)

Large

boulder

(>12 in.)

Bedrock or 

compact

alluvium

ÿöpaekalaÿole 

(Atyoida bisulcata) 0.2 0.2 0.2 0.2 0.5 1 0.2

ÿoÿopu ÿalamoÿo, adult 

(Lentipes concolor) 0.2 0.2 0.2 0.2 0.2 1 0.2

ÿoÿopu ÿalamoÿo, juvenile 

(Lentipes concolor) 0.2 0.2 0.2 0.2 0.5 1 0.2

ÿoÿopu nöpili, adult 

(Sicyopterus stimpsoni) 0.2 0.2 0.2 1 1 1 0.2

ÿoÿopu nöpili, juvenile 

(Sicyopterus stimpsoni) 0.2 0.2 0.2 0.5 1 1 0.2

ÿoÿopu näkea, adult

(Awaous guamensis) 0.2 0.2 0.5 1 1 1 0.2

hïhïwai 

(Neritina granosa) 0.2 0.2 0.2 0.5 0.5 1 0.2

Effects of Surface-Water Diversions on Physical Habitat 101
ÿOÿopu ÿalamoÿo

Adult

Juvenile

AdultJuvenile

ÿOÿopu nöpili

0.0

0.0

0.2

0.4

0.6

0.8

1.0

0.0

0.2

0.4

0.6

0.8

1.0

0.0

0.2

0.4

0.6

0.8

1.0

0.5 1.0

FROUDE NUMER

1.5

0.0 0.5 1.0

FROUDE NUMBER

1.5

ÿOÿopu näkea ÿÖpaekalaÿole

SUITABILITY

Hïhïwai

Figure 62. Froude number suitability curves for selected native stream fauna, Maui, Hawaiÿi (modified from 

Gingerich and Wolff, 2005). Curves dashed where extrapolated.

102 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
ÿOÿopu ÿalamoÿo

JuvenileAdultJuvenileAdult

ÿOÿopu nöpili

0

0.0

0.2

0.4

0.6

0.8

1.0

0.0

0.2

0.4

0.6

0.8

1.0

0.0

0.2

0.4

0.6

0.8

1.0

1 2

DEPTH, IN FEET

3 4

0 1 2 3 4

0 2 4 6 8 0 1 2 3 4

0 1 2

DEPTH, IN FEET

3 4

ÿOÿopu näkea ÿÖpaekalaÿole

SUITABILITY

Hïhïwai

Figure 63. Depth suitability curves for selected native stream fauna, Maui, Hawaiÿi (modified from 

Gingerich and Wolff, 2005). Curves dashed where extrapolated.

Effects of Surface-Water Diversions on Physical Habitat 103
0

0 20 40 60 80 100 120 140 0 20 40 60 80 100 120 140

10 20 30 40 0 10 20 30 40

DISCHARGE, IN MILLION GALLONS PER DAY

DISCHARGE, IN PERCENTAGE OF NATURAL Q70 DISCHARGE

0

20

40

60

80

100

120

0

20

40

60

80

100

120

0

20

40

60

80

100

120

0

20

40

60

80

100

120

HABITAT (WEIGHTED USABLE AREA), IN PERCENTAGE OF HABITAT AT NATURAL Q70 DISCHARGE

HABITAT (WEIGHTED USABLE AREA), IN SQUARE FEET PER 1,000 FEET

0

6,000

4,000

2,000

8,000

0

2,000

4,000

6,000

8,000

10,000

12,000

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

ÿOÿopu ÿalamoÿo, adult ÿOÿopu ÿalamoÿo, juvenile

ÿOÿopu näkea ÿÖpaekalaÿole

A

Predicted (best fit power function)

Predicted (at selected discharges)

Measured

Q Q50

Q 70 90

Q99

Figure 64. Relations between habitat (weighted usable area) for selected native species and discharge 

in Waiheÿe River, Maui, Hawaiÿi. A, Altitude of 570 feet. B, Altitude of 405 feet. C, Altitude of 30 feet. The 

Qp discharge is the discharge equaled or exceeded p percent of the time. The natural, undiverted flow 

characteristics at an altitude of 570 feet are assumed to be equivalent to those at an altitude of 605 feet, 

and the natural, undiverted flow characteristics at an altitude of 30 feet are assumed to be equivalent to 

those at an altitude of 45 feet.

10,000 ft2 per 1,000 ft of stream for some species and flows 

(figs. 64–67).

Available hydrograph-separation analyses for undiverted 

Hawaiian streams indicate that median base flow values 

generally are in the range of the Q60 to Q80 duration flows 

(Fontaine, 2003; Oki, 2004; Gingerich, 2005; Oki and others, 

2006). For this study, normalized relations between habitat 

and discharge were developed by dividing habitat values 

by the habitat at the natural, undiverted Q70 discharge and 

by dividing discharge values by the natural, undiverted Q70

discharge (figs. 64–67). (The natural, undiverted Q70 discharge 

for each habitat study reach was determined from the nearest 

available site at which flow characteristics were estimated 

(tables 18–21). Flow characteristics were estimated for sites 

within or immediately upstream or downstream of each 

study reach.) Normalizing the relations between habitat and 

discharge allowed comparisons to be made among species 

and streams. Available data from the different species and 

streams were used to develop a generalized relation between 

habitat and discharge (fig. 68). This generalized relation 

indicates increased physical habitat for increased discharge, 

which is consistent with the individual relations (figs. 64–67). 

The generalized relation indicates that at a discharge equal to 

20 percent of the Q70 discharge, the physical habitat (WUA) 

104 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Figure 64.—Continued. 

0

0 20 40 60 80 100 120 0 20 40 60 80 100 120

10 20 30 40 0 10 20 30 40

DISCHARGE, IN MILLION GALLONS PER DAY

DISCHARGE, IN PERCENTAGE OF NATURAL Q70 DISCHARGE

0

20

40

60

80

100

120

0

20

40

60

80

100

120

0

20

40

60

80

100

120

0

20

40

60

80

100

120

HABITAT (WEIGHTED USABLE AREA), IN PERCENTAGE OF HABITAT AT NATURAL Q70 DISCHARGE

HABITAT (WEIGHTED USABLE AREA), IN SQUARE FEET PER 1,000 FEET

0

10,000

8,000

6,000

4,000

2,000

12,000

0

2,000

4,000

6,000

8,000

10,000

12,000

0

2,000

6,000

4,000

8,000

10,000

12,000

14,000

16,000

18,000

0

2,000

4,000

6,000

8,000

10,000

12,000

ÿOÿopu nöpili, adult ÿOÿopu nöpili, juvenile

ÿOÿopu näkea Hïhïwai

B

Predicted (best fit power function)

Predicted (at selected discharges)

Measured

Q99 Q90 Q70 Q50

is about 67 percent of the habitat at the Q70 discharge; at a 

discharge equal to 50 percent of the Q70 discharge, WUA 

is about 84 percent of the habitat at the Q70 discharge. The 

relation between physical habitat and discharge developed for 

this study generally is consistent with results from Gingerich 

and Wolff (2005). Results for a specific species and site may 

vary from the generalized relation, as indicated by the scatter 

in the data (fig. 68). For example, the generalized relation may 

predict greater habitat, for a given discharge, than data for 

hïhïwai indicate (fig. 68). However, the generalized relation 

is useful as an indicator of how habitat varies with discharge, 

particularly for sites without available data.

Reduction of Habitat Caused by Diversions

To evaluate the effects of existing surface-water 

diversions on physical habitat, the generalized relation 

between habitat and discharge (fig. 68) was used in 

conjunction with estimates of streamflow for different 

diversion intake capacities (see previous section on “Effects 

of Surface-Water Diversions on Streamflow”). The weightedaverage physical habitat (in terms of WUA) available during 

low-flow conditions at selected sites downstream of diversions 

was computed for both undiverted and diverted conditions, 

and the percentage reduction in habitat between undiverted 

Effects of Surface-Water Diversions on Physical Habitat 105
and diverted conditions was computed. The effects of the 

diversions on habitat were determined at selected flows equal 

to and less than the median flow (Q50, Q55, Q60, Q65, Q70, Q75, 

Q80, Q85, Q90, Q95, and Q99). At each flow, the habitat was 

weighted by the percentage of time that flow occurs during 

low-flow conditions to provide an estimate of the weightedaverage habitat available during low-flow conditions. The 

percentage of time that each selected flow occurs was 

determined by half of the difference between duration 

percentiles of adjacent duration discharges. For example, the 

percentage of time that the Q55 flow was assumed to occur was 

equal to (60-50)/2, or 5 percent. During low-flow conditions, 

when flow is less than the median flow, the Q55 flow occurs 

10 (=5×2) percent of the time. The percentage of time that the 

Q50 flow was assumed to occur was equal to (55-50)/2, or 2.5 

percent. During low-flow conditions, when flow is less than 

the median flow, the Q50 flow occurs 5 (=2.5×2) percent of the 

time. Thus, for the Q50 flow, the habitat was multiplied by 0.05 

(equal to 5 percent of the time during low-flow conditions); 

for the Q55 to Q90 flows, the habitat was multiplied by 0.1; for 

the Q95 flow, the habitat was multiplied by 0.09; and for the 

Q99 flow, the habitat was multiplied by 0.06. The sum of the 

weights is equal to 1.

 Diversion of surface water from a stream generally 

reduces the amount of physical habitat available during lowflow conditions. Thus, as the capacity of the diversion intakes 

increase, the reduction in habitat generally increases. At some 

level of diversion intake capacity, the reach immediately 

downstream of the diversion may have zero flow during 

dry-weather conditions, the effects of diversions on habitat 

reduction may reach a maximum value, and increased 

diversion intake capacity has no further effect on reducing 

habitat during dry-weather conditions. The reported habitat 

reductions are for periods when the upstream, undiverted 

flows are less than or equal to the median flow, which occurs 

50 percent of the time. Also, for the purposes of this analysis, 

none of the diverted water is assumed to return to the stream.

0

0 20 40 60 80 100 120 140 0 20 40 60 80 100 120 140

10 20 30 40 0 10 20 30 40

DISCHARGE, IN MILLION GALLONS PER DAY

DISCHARGE, IN PERCENTAGE OF NATURAL Q70 DISCHARGE

0

20

40

60

80

100

120

0

20

40

60

80

100

120

0

20

40

60

80

100

120

0

20

40

60

80

100

120

HABITAT (WEIGHTED USABLE AREA), IN PERCENTAGE OF HABITAT AT NATURAL Q70 DISCHARGE

0

10,000

8,000

6,000

4,000

2,000

12,000

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

18,000

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

ÿOÿopu nöpili, adult ÿOÿopu nöpili, juvenile

ÿOÿopu näkea Hïhïwai

C

HABITAT (WEIGHTED USABLE AREA), IN SQUARE FEET PER 1,000 FEET

Predicted (best fit power function)

Predicted (at selected discharges)

Measured

Q Q50 Q 70 90 Q99

Figure 64.—Continued. 

106 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Waiheÿe River

Reduction in physical habitat (WUA), relative to 

undiverted low-flow conditions, caused by diversions into 

the Waihe‘e, Spreckels, and Field 1 intakes was estimated 

for Waihe‘e River near an altitude of 45 ft (fig. 69) using 

the generalized relation between habitat and discharge. The 

effects of diversions on physical habitat near an altitude of 

45 ft in Waihe‘e River were evaluated for diversion intake 

capacities of 0 to 39 Mgal/d (0 to 60 ft3/s) for the Waihe‘e 

Ditch; 0 to 39 Mgal/d (0 to 60 ft3/s) for Spreckels Ditch; 

and 0 or 3.2 Mgal/d (0 or 5 ft3/s) for the Field 1 intake. The 

intake capacity for the Field 1 diversion is unknown and, 

thus, the use of 3.2 Mgal/d (5 ft3/s) for the intake capacity 

of the Field 1 intake is arbitrary. The family of curves (fig. 

69), with each curve corresponding to a selected value of 

habitat reduction, shows the relation between capacities of 

the diversion intakes and habitat reduction during low-flow 

conditions. If no water is diverted at the Field 1 intake, then 

combinations of diversion intake capacities for Waihe‘e and 

Spreckels Ditches equal to 32.6 Mgal/d (50.4 ft3

/s) result 

in 100 percent reduction in physical habitat near an altitude 

of 45 ft (fig. 69A). Thus, if the intake capacity of Waihe‘e 

Ditch is 32.6 Mgal/d (50.4 ft3/s) and no water is diverted 

by Spreckels Ditch, then physical habitat will be reduced 

by 100 percent near an altitude of 45 ft. Similarly, if the 

intake capacity of Waihe‘e Ditch is 16.3 Mgal/d (25.2 ft3/s) 

and the intake capacity of Spreckels Ditch is the same, then 

physical habitat also will be reduced by 100 percent near an 

altitude of 45 ft (fig. 69A). Existing diversions by Waihe‘e 

and Spreckels Ditches, with reported intake capacities of 40 

and 12 Mgal/d (62 and 19 ft3/s), respectively, reduce physical 

habitat near an altitude of 45 ft by 100 percent during lowflow periods if no water is diverted at the Field 1 intake and 

if no water is returned to the stream upstream of an altitude 

of 45 ft (fig. 69A).

If no water is diverted at the Field 1 intake, then 

combinations of diversion intake capacities for Waihe‘e and 

Spreckels Ditches equal to 22.9 Mgal/d (35.4 ft3/s) result in 

50 percent reduction in physical habitat near an altitude of 45 

ft (fig. 69A). If 3.2 Mgal/d (5 ft3

/s) is diverted at the Field 1 

intake, then combinations of diversion intake capacities for 

Waihe‘e and Spreckels Ditches equal to 19.6 Mgal/d (30.4 

ft3

/s) result in 50 percent reduction in physical habitat near 

an altitude of 45 ft (fig. 69B).

Waiehu Stream

Reduction in physical habitat (WUA), relative to 

undiverted low-flow conditions, caused by diversions into 

the North Waiehu Ditch, Spreckels Ditch, and two existing 

private ‘auwai with intakes near altitudes of 620 and 570 ft 

in South Waiehu Stream was estimated for Waiehu Stream 

near an altitude of 20 ft (fig. 70) using the generalized relation 

between habitat and discharge. The effects of diversions on 

physical habitat near an altitude of 20 ft in Waiehu Stream 

were evaluated for diversion intake capacities of 0 to 3.2 

Mgal/d (0 to 5 ft3

/s) for North Waiehu Ditch, North Waiehu 

Stream; 0 to 3.2 Mgal/d (0 to 5 ft3/s) for Spreckels Ditch, 

South Waiehu Stream; and 0 or 0.32 Mgal/d (0 or 0.5 ft3

/s) 

each for two existing private ‘auwai with intakes near altitudes 

of 620 and 570 ft, South Waiehu Stream. The diversion intake 

capacities for the two existing private ‘auwai are unknown and 

variable, depending on the condition of the intakes. For this 

study, the intake capacity of each private ‘auwai was assumed 

to be either 0 (fig. 70A) or 0.32 Mgal/d (0.5 ft3/s) (fig. 70B), 

which generally represents the range of available measured 

diversion rates. The family of curves (fig. 70), with each curve 

corresponding to a selected value of habitat reduction, shows the 

relation between capacities of the diversion intakes and habitat 

reduction during low-flow conditions. Existing diversions by 

the North Waiehu Ditch, with a reported capacity of 1.5 Mgal/d 

(2.3 ft3/s), and Spreckels Ditch, with a capacity that exceeds 1 

Mgal/d (1.5 ft3

/s), reduce physical habitat near an altitude of 20 

ft by at least 60 percent, even if no water is diverted by each of 

the two private ‘auwai and if no water is returned to the stream 

upstream of an altitude of 20 ft (fig. 70A). 

If no water is diverted by the two private ‘auwai, then 

different combinations of diversion intake capacities for 

North Waiehu and Spreckels Ditches may result in 50 percent 

reduction in physical habitat near an altitude of 20 ft (fig. 

70A). For example, if the intake capacity for North Waiehu 

Ditch is 0.65 Mgal/d (1.0 ft3/s) and the intake capacity for 

Spreckels Ditch is about 1.1 Mgal/d (1.7 ft3/s), then physical 

habitat will be reduced by 50 percent near an altitude of 20 ft 

(fig. 70A). Similarly, if the intake capacity for North Waiehu 

Ditch is 1.3 Mgal/d (2.0 ft3/s) and the intake capacity for 

Spreckels Ditch is about 0.65 Mgal/d (1.0 ft3/s), then physical 

habitat also will be reduced by 50 percent near an altitude of 

20 ft (fig. 70A). 

If 0.32 Mgal/d (0.5 ft3/s) is diverted by each of the 

two existing private ‘auwai of South Waiehu Stream, then 

different combinations of diversion intake capacities for 

North Waiehu and Spreckels Ditches may result in 50 

percent reduction in physical habitat near an altitude of 20 

ft (fig. 70B). For example, if the intake capacity for North 

Waiehu Ditch is 0.65 Mgal/d (1.0 ft3/s) and the intake 

capacity for Spreckels Ditch is about 0.43 Mgal/d (0.67 

ft3

/s), then physical habitat will be reduced by 50 percent 

near an altitude of 20 ft (fig. 70B). Similarly, if the intake 

capacity for North Waiehu Ditch is 1.3 Mgal/d (2.0 ft3/s) and 

the intake capacity for Spreckels Ditch is about 0.03 Mgal/d 

(0.05 ft3/s), then physical habitat also will be reduced by 50 

percent near an altitude of 20 ft (fig. 70B). 

ÿĪao Stream

Reduction in physical habitat (WUA), relative to 

undiverted low-flow conditions, caused by diversions into the 

Effects of Surface-Water Diversions on Physical Habitat 107
ÿOÿopu ÿalamoÿo, adult ÿOÿopu ÿalamoÿo, juvenile

ÿOÿopu nöpili, adult ÿOÿopu nöpili, juvenile

0

0 20 40 60 80 100 120 140 160 0

0

20

40

60

80

100

120

0

20

40

60

80

100

120

0

20

40

60

80

100

120

0

20

40

60

80

100

120

0

20

40

60

80

100

120

0

20

40

60

80

100

120

20 40 60 80 100 120 140 160

1 2 3 4

ÿOÿopu näkea

0 1 2 3 4

ÿÖpaekalaÿole

DISCHARGE, IN MILLION GALLONS PER DAY

DISCHARGE, IN PERCENTAGE OF NATURAL Q70 DISCHARGE

HABITAT (WEIGHTED USABLE AREA), IN SQUARE FEET PER 1,000 FEET

HABITAT (WEIGHTED USABLE AREA), IN PERCENTAGE OF HABITAT AT NATURAL Q70 DISCHARGE

0

500

1,000

1,500

2,000

0

500

1,000

1,500

2,000

2,500

3,000

3,500

0

1,000

2,000

3,000

4,000

5,000

6,000

0

1,000

2,000

3,000

4,000

5,000

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

0

200

400

600

800

1,000

1,200

A

Predicted (best fit power function)

Predicted (at selected discharges)

Measured

Q50

Q70

Q90

Q99

Figure 65. Relations between habitat (weighted usable area) for selected native species and discharge 

in Waiehu Stream, Maui, Hawaiÿi. A, Altitude of 820 feet in North Waiehu Stream. B, Altitude of 185 feet in 

Waiehu Stream. The Qp discharge is the discharge equaled or exceeded p percent of the time. The natural, undiverted flow characteristics of North Waiehu Stream at an altitude of 820 feet are assumed to be 

equivalent to those at an altitude of 880 feet, and the natural, undiverted flow characteristics of Waiehu 

Stream at an altitude of 185 feet are assumed to be equivalent to those at an altitude of 190 feet.

108 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
‘Īao-Waikapū and ‘Īao-Māniania Ditches, Spreckels Ditch, 

and an existing private ‘auwai was estimated for ‘Īao Stream 

near an altitude of 35 ft (fig. 71) using the generalized relation 

between habitat and discharge. The effects of diversions on 

physical habitat near an altitude of 35 ft in ‘Īao Stream were 

evaluated for diversion intake capacities of 0 to 26 Mgal/d (0 

to 40 ft3/s) for the ‘Īao-Waikapū and ‘Īao-Māniania Ditches; 

0 to 26 Mgal/d (0 to 40 ft3/s) for Spreckels Ditch; and 0 or 

0.65 Mgal/d (0 or 1 ft3/s) for an existing private ‘auwai with 

an intake at an altitude of about 650 ft. The diversion intake 

capacity for the existing private ‘auwai is unknown but much 

less than the current diversion intake capacities for the ‘ĪaoWaikapū and ‘Īao-Māniania Ditches and Spreckels Ditch. 

For this study, the intake capacity of the private ‘auwai was 

assumed to be either 0 (fig. 71A) or 0.65 Mgal/d (1 ft3/s) 

(fig. 71B), which covers the range of available measured 

diversion rates. The family of curves (fig. 71), with each curve 

corresponding to a selected value of habitat reduction, shows 

the relation between capacities of the diversion intakes and 

habitat reduction during low-flow conditions. If no water is 

diverted by the existing private ‘auwai, then combinations 

of diversion intake capacities for ‘Īao-Waikapū and ‘ĪaoMāniania Ditches and Spreckels Ditch equal to 21.2 Mgal/d 

(32.9 ft3/s) result in 100 percent reduction in physical habitat 

near an altitude of 35 ft (fig. 71A). Existing diversions by the 

‘Īao-Waikapū and ‘Īao-Māniania Ditches, with a reported 

capacity of 20 Mgal/d (31 ft3/s), and Spreckels Ditch, with 

an intake capacity that likely exceeds several Mgal/d, reduce 

physical habitat near an altitude of 35 ft by 100 percent 

during low-flow periods if no water is returned to ‘Īao Stream 

upstream of an altitude of 35 ft (fig. 71A).

If no water is diverted by the existing private ‘auwai, 

then combinations of diversion intake capacities for the ‘ĪaoWaikapū and ‘Īao-Māniania Ditches and Spreckels Ditch 

Figure 65.—Continued. 

0

0 20 40 60 80 100 120 140 160

1 2 3 4 0 1 2 3 4

DISCHARGE, IN MILLION GALLONS PER DAY

DISCHARGE, IN PERCENTAGE OF NATURAL Q70 DISCHARGE

0 20 40 60 80 100 120 140 160

0

20

40

60

80

100

120

140

0

20

40

60

80

100

120

140

0

20

40

60

80

100

120

140

0

20

40

60

80

100

120

140

HABITAT (WEIGHTED USABLE AREA), IN PERCENTAGE OF HABITAT AT NATURAL Q70 DISCHARGE

HABITAT (WEIGHTED USABLE AREA), IN SQUARE FEET PER 1,000 FEET

0

5,000

3,000

4,000

2,000

1,000

6,000

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

0

1,000

3,000

2,000

4,000

5,000

6,000

7,000

8,000

9,000

0

500

1,000

1,500

2,000

2,500

3,000

ÿOÿopu nöpili, adult ÿOÿopu nöpili, juvenile

ÿOÿopu näkea Hïhïwai

B

Predicted (best fit power function)

Predicted (at selected discharges)

Measured

Q50 Q70

Q90

Q99

Effects of Surface-Water Diversions on Physical Habitat 109
ÿOÿopu ÿalamoÿo, adult ÿOÿopu ÿalamoÿo, juvenile

ÿOÿopu nöpili, adult ÿOÿopu nöpili, juvenile

0

0 20 40 60 80 100 120 140 160 0 20 40 60 80 100 120 140 160

0

20

40

60

80

100

140

120

0

20

40

60

80

100

140

120

0

20

40

60

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120

0

20

40

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120

0

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40

60

80

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0

20

40

60

80

100

140

120

5 10 15 20 25 30 0 5 10 15 20 25 30

ÿOÿopu näkea ÿÖpaekalaÿole

DISCHARGE, IN MILLION GALLONS PER DAY

DISCHARGE, IN PERCENTAGE OF NATURAL Q70 DISCHARGE

HABITAT (WEIGHTED USABLE AREA), IN SQUARE FEET PER 1,000 FEET

HABITAT (WEIGHTED USABLE AREA), IN PERCENTAGE OF HABITAT AT NATURAL Q70 DISCHARGE

0

4,000

3,000

2,000

1,000

5,000

6,000

0

2,000

4,000

6,000

8,000

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0

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0

1,000

2,000

3,000

4,000

5,000

6,000

A

Predicted (best fit power function)

Predicted (at selected discharges)

Measured

Q50

Q70

Q90

Q99

Figure 66. Relations between habitat (weighted usable area) for selected native species and discharge 

in ÿÏao Stream, Maui, Hawaiÿi. A, Altitude of 730 feet. B, Altitude of 570 feet. The Qp discharge is the 

discharge equaled or exceeded p percent of the time. The natural, undiverted flow characteristics at an 

altitude of 730 feet are assumed to be equivalent to those at an altitude of 725 feet, and the natural, undiverted flow characteristics at an altitude of 570 feet are assumed to be equivalent to those at an altitude 

of 595 feet.

110 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
equal to 9.8 Mgal/d (15.2 ft3

/s) result in 50 percent reduction 

in physical habitat near an altitude of 35 ft (fig. 71A). If 0.65 

Mgal/d (1 ft3/s) is diverted by the existing private ‘auwai, 

then combinations of diversion intake capacities for the ‘ĪaoWaikapū and ‘Īao-Māniania Ditches and Spreckels Ditch 

equal to 9.2 Mgal/d (14.2 ft3/s) result in 50 percent reduction 

in physical habitat near an altitude of 45 ft (fig. 71B).

Waikapu ̄ Stream

Reduction in physical habitat (WUA), relative to 

undiverted low-flow conditions, caused by diversions into the 

South Side Ditch, Everett Ditch, an existing private ‘auwai 

with an intake near an altitude of 560 ft, Waihe‘e Ditch, and 

the Reservoir 6 Ditch was estimated for Waikapū Stream near 

an altitude of 400 ft (fig. 72) using the generalized relation 

between habitat and discharge. The effects of diversions on 

physical habitat near an altitude of 400 ft in Waikapū Stream 

were evaluated for diversion intake capacities of 0 to 6.5 

Mgal/d (0 to 10 ft3/s) for the South Side Ditch; 0 to 6.5 Mgal/d 

(0 to 10 ft3/s) for the combined capacity of a private ‘auwai 

with an intake near an altitude of 560 ft, Waihe‘e Ditch, and 

the Reservoir 6 diversion; and 0 or 0.65 Mgal/d (0 or 1 ft3/s) 

for Everett Ditch. For this study, the intake capacity of Everett 

Ditch was assumed to be either 0 (fig. 72A) or 0.65 Mgal/d (1 

ft3/s) (fig. 72B), which covers the range of available measured 

diversion rates. The family of curves (fig. 72), with each 

curve corresponding to a selected value of habitat reduction, 

shows the relation between capacities of the diversion intakes 

and habitat reduction during low-flow conditions. Existing 

diversions by the South Side Ditch, with a reported capacity 

of 3 Mgal/d (4.6 ft3/s), and the private ‘auwai with intake near 

an altitude of 560 feet, Waihe‘e Ditch, and Reservoir 6 Ditch, 

0 20 40 60 80 100 120 140 160 0 20 40 60 80 100 120 140 160

50 10 15 20 25 30

50 10 15 20 25 30

DISCHARGE, IN MILLION GALLONS PER DAY

DISCHARGE, IN MILLION GALLONS PER DAY

DISCHARGE, IN PERCENTAGE OF NATURAL Q70 DISCHARGE

0

20

40

60

80

100

120

0

20

40

60

80

100

120

0

20

40

60

80

100

120

HABITAT (WEIGHTED USABLE AREA), IN PERCENTAGE OF HABITAT AT NATURAL Q70 DISCHARGE

HABITAT (WEIGHTED USABLE AREA),

IN SQUARE FEET PER 1,000 FEET

HABITAT (WEIGHTED USABLE AREA),

IN SQUARE FEET PER 1,000 FEET

0

12,000

8,000

6,000

10,000

4,000

2,000

14,000

12,000

8,000

6,000

10,000

4,000

2,000

14,000

0

0

5,000

10,000

15,000

20,000

ÿOÿopu nöpili, adult ÿOÿopu nöpili, juvenile

ÿOÿopu näkea

B

Predicted (best fit power function)

Predicted (at selected discharges)

Measured

Q50 Q70

Q90

Q99

Figure 66.—Continued. 

Effects of Surface-Water Diversions on Physical Habitat 111
0

0 20 40 60 80 100 120 140 0 20 40 60 80 100 120 140

1 2 3 4 5 0 1 2 3 4 5

DISCHARGE, IN MILLION GALLONS PER DAY

DISCHARGE, IN PERCENTAGE OF NATURAL Q70 DISCHARGE

0

20

40

60

80

100

120

0

20

40

60

80

100

120

0

20

40

60

80

100

120

0

20

40

60

80

100

120

HABITAT (WEIGHTED USABLE AREA), IN PERCENTAGE OF HABITAT AT NATURAL Q70 DISCHARGE

HABITAT (WEIGHTED USABLE AREA), IN SQUARE FEET PER 1,000 FEET

0

1,000

500

1,500

0

500

1,000

1,500

2,000

2,500

3,000

0

2,000

4,000

6,000

8,000

10,000

0

500

1,000

1,500

2,000

ÿOÿopu ÿalamoÿo, adult ÿOÿopu ÿalamoÿo, juvenile

ÿOÿopu näkea ÿÖpaekalaÿole

A

Predicted (best fit power function)

Predicted (at selected discharges)

Measured

Q50

Q70

Q90

Q99

Figure 67. Relations between habitat (weighted usable area) for selected native species and discharge 

in Waikapü Stream, Maui, Hawaiÿi. A, Altitude of 1,050 feet. B, Altitude of 840 feet. The Qp

 discharge is 

the discharge equaled or exceeded p percent of the time. The natural, undiverted flow characteristics 

at an altitude of 1,050 feet are assumed to be equivalent to those at an altitude of 1,080 feet, and the 

natural, undiverted flow characteristics at an altitude of 840 feet are assumed to be equivalent to those at 

an altitude of 820 feet.

with a combined intake capacity that likely exceeds 2 Mgal/d 

(3.1 ft3/s), reduce physical habitat near an altitude of 400 ft by 

more than 90 percent during low-flow periods if no water is 

diverted by the Everett Ditch and if no water is returned to the 

stream upstream of an altitude of 400 feet (fig. 72A). 

If no water is diverted by Everett Ditch, then different 

combinations of diversion intake capacity for the South Side 

Ditch and combined intake capacity for the existing private 

‘auwai, Waihe‘e Ditch, and Reservoir 6 Ditch may result in 

50 percent reduction in physical habitat near an altitude of 

400 ft (fig. 72A). For example, if the intake capacity for the 

South Side Ditch is 0.65 Mgal/d (1.0 ft3/s) and the combined 

capacity for the intakes of the existing private ‘auwai, Waihe‘e 

Ditch, and Reservoir 6 Ditch is about 2.8 Mgal/d (4.3 ft3/s), 

then physical habitat will be reduced by 50 percent near an 

altitude of 400 ft (fig. 72A). Similarly, if the intake capacity for 

the South Side Ditch is 1.9 Mgal/d (3.0 ft3/s) and the combined 

capacity for the intakes of the existing private ‘auwai, Waihe‘e 

Ditch, and Reservoir 6 Ditch is about 1.5 Mgal/d (2.3 ft3/s), 

then physical habitat also will be reduced by 50 percent near 

an altitude of 400 ft (fig. 72A).

If the intake capacity for the Everett Ditch is 0.65 Mgal/d 

(1 ft3/s), then different combinations of diversion intake 

capacity for the South Side Ditch and combined intake capacity 

112 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
for the existing private ‘auwai, Waihe‘e Ditch, and Reservoir 

6 Ditch may result in 50 percent reduction in physical habitat 

near an altitude of 400 ft (fig. 72B). For example, if the intake 

capacity for the South Side Ditch is 0.65 Mgal/d (1.0 ft3/s) and 

the combined capacity for the intakes of the existing private 

‘auwai, Waihe‘e Ditch, and Reservoir 6 Ditch is about 2.1 

Mgal/d (3.3 ft3/s), then physical habitat will be reduced by 50 

percent near an altitude of 400 ft (fig. 72B). Similarly, if the 

intake capacity for the South Side Ditch is 1.9 Mgal/d (3.0 

ft3/s) and the combined capacity for the intakes of the existing 

private ‘auwai, Waihe‘e Ditch, and Reservoir 6 Ditch is about 

0.84 Mgal/d (1.3 ft3/s), then physical habitat also will be 

reduced by 50 percent near an altitude of 400 ft (fig. 72B).

Effects of Surface-Water Diversions 

on Water Temperature

Upstream diversion of surface water results in decreased 

flow and, possibly, increased stream temperatures in 

downstream reaches. Reduced streamflow will lead to lower 

water velocities and longer traveltimes for water to flow to 

the ocean. Because of the longer traveltimes, water is exposed 

to potential heating from the sun for longer periods. In 

stream reaches that gain water, upstream diversion of surface 

water may result in decreased water temperatures if local 

Figure 67.—Continued. 

0 20 40 60 80 100 120 0 20 40 60 80 100 120

10 2 3 654

10 2 3 654

DISCHARGE, IN MILLION GALLONS PER DAY

DISCHARGE, IN MILLION GALLONS PER DAY

DISCHARGE, IN PERCENTAGE OF NATURAL Q70 DISCHARGE

0

20

40

60

80

100

120

0

20

40

60

80

100

120

0

20

40

60

80

100

120

HABITAT (WEIGHTED USABLE AREA), IN PERCENTAGE OF HABITAT AT NATURAL Q70 DISCHARGE

HABITAT (WEIGHTED USABLE AREA),

IN SQUARE FEET PER 1,000 FEET

HABITAT (WEIGHTED USABLE AREA),

IN SQUARE FEET PER 1,000 FEET

0

6,000

4,000

3,000

5,000

2,000

1,000

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

0

2,000

4,000

6,000

8,000

10,000

ÿOÿopu nöpili, adult ÿOÿopu nöpili, juvenile

ÿOÿopu näkea

B

Predicted (best fit power function)

Predicted (at selected discharges)

Measured

Effects of Surface-Water Diversions on Water Temperature 113
groundwater discharge that is cooler than the diverted water 

becomes the dominant source of water in the stream. 

Stream temperature is a factor that could potentially 

affect the abundance and distribution of native aquatic species 

and wetland-taro production. Hathaway (1978) indicated 

that the upper lethal temperature limits for native aquatic 

species generally range from about 35°C to 40°C. Wetlandtaro agriculture commonly is dependent on surface water 

from streams for irrigation water. Ooka (1994) indicated that 

water temperatures exceeding 27°C favors Pythium rot, which 

transforms the normally firm flesh of the corm of taro into 

a soft, mushy, often malodorous mass. Pardales and others 

(1982) indicated that water temperatures above 29°C seemed 

to be detrimental to root growth in newly planted taro. 

To evaluate the effects of diversion of water on stream 

temperatures in the Nā Wai ‘Ehā area, temperature-recording 

sensors were placed immediately upstream of all diversions 

and at selected downstream sites. Temperature was monitored 

at a total of 18 sites: 4 each on ‘Īao and Waiehu Streams, and 

5 each on Waikapū Stream and Waihe‘e River (figs. 21–24, 

table 24). The sensors generally were placed near the stream 

thalweg (low point in the stream) to ensure that they remained 

submerged for all flow conditions that occurred during the 

study period and that water continuously flowed past the 

sensors. Sensors were placed in shaded or partially shaded 

locations where possible. All temperature-recording sensors 

were programmed to measure temperature at 15-minute 

intervals during the period between September 2006 and 

October 2007. At some sites, data were lost because of 

vandalism, equipment failure, or loss of equipment during 

periods of high flow. 

Daily Mean Temperatures

During the period when temperatures were measured for 

this study, daily mean water temperatures at the studied sites 

ranged from 16.5°C to 24.8°C (figs. 73–76). The lowest daily 

Habitat = (1001-0.2413) Discharge0.2413

0 20 40 60 80

DISCHARGE, IN PERCENTAGE OF NATURAL Q70 DISCHARGE

100 120 140 160

0

20

40

60

80

100

120

140

HABITAT (WEIGHTED USABLE AREA), IN PERCENTAGE OF HABITAT AT NATURAL Q70 DISCHARGE

WAIHEÿE RIVER

WAIEHU STREAM

ÿÏAO STREAM

WAIKAPÜ STREAM

HÏHÏWAI

Figure 68. Generalized relation between habitat and discharge for ÿoÿopu ÿalamoÿo, ÿoÿopu no ̄pili, 

ÿoÿopu näkea, ÿo ̄paekalaÿole, and hïhïwai in Waiheÿe River and Waiehu, ÿÏao, and Waikapü Streams, 

Maui, Hawaiÿi.

114 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
10

20

30

40

50

60

70

80

90

100

10

20

30

40

50

60

70

80

90

100

LINE OF EQUAL ESTIMATED HABITAT REDUCTION

IN WAIHEÿE RIVER, IN PERCENTAGE REDUCTION

RELATIVE TO UNDIVERTED LOW-FLOW 

CONDITIONS—Interval 10 percent

50

0 10 20 30

CAPACITY OF WAIHEÿE DITCH INTAKES, WAIHEÿE RIVER, IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE, WAIHEÿE RIVER, IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE, WAIHEÿE RIVER, IN MILLION GALLONS PER DAY

40 50 60

0 5 10 15

CAPACITY OF WAIHEÿE DITCH INTAKES, WAIHEÿE RIVER, IN MILLION GALLONS PER DAY

20 25 30 35

0

10

20

30

40

50

60

0

5

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20

25

30

35

0

5

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20

25

30

35

0

10

20

30

40

50

60

A

B

Figure 69. Reduction in physical habitat (average weighted usable area), relative to undiverted conditions, caused by diversions into the Waiheÿe Ditch and Spreckels Ditch with indicated intake capacities, Waiheÿe River near an altitude of 45 feet, Maui, Hawaiÿi. A, Zero diversion into the Field 1 intake. 

B, Diversion capacity of 3.2 million gallons per day (5 cubic feet per second) for the Field 1 intake. 

Habitat reduction computed for low-flow periods, when streamflow is less than or equal to the median 

discharge, using generalized relation between habitat and discharge. A ditch intake is assumed to 

divert at a rate up to, but not exceeding, the indicated capacity (if streamflow is less than the indicated 

capacity, then all streamflow at the ditch intake is assumed to be diverted).

Effects of Surface-Water Diversions on Water Temperature 115
20 10

20

30

40

30

40

50

60

70

80

90

100

50

60

70

80

90

100

LINE OF EQUAL ESTIMATED HABITAT 

REDUCTION IN WAIEHU STREAM, IN 

PERCENTAGE REDUCTION RELATIVE

TO UNDIVERTED LOW-FLOW 

CONDITIONS—Interval 10 percent

50

0.0 0.5 1.0 1.5 2.0 2.5 3.0 4.5

CAPACITY OF NORTH WAIEHU DITCH INTAKE, NORTH WAIEHU STREAM, IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE, SOUTH WAIEHU STREAM, IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE, SOUTH WAIEHU STREAM, IN MILLION GALLONS PER DAY

3.5 4.0 5.0

0 0.5 1.0 1.5

CAPACITY OF NORTH WAIEHU DITCH INTAKE, NORTH WAIEHU STREAM, IN MILLION GALLONS PER DAY

2.0 2.5 3.0

0.0

1.0

0.5

2.0

1.5

2.5

3.5

3.0

4.5

4.0

5.0

0.0

1.0

0.5

2.0

1.5

2.5

3.5

3.0

4.5

4.0

5.0

0.0

0.5

1.0

1.5

2.0

2.5

3.0

0.0

0.5

1.0

1.5

2.0

2.5

A 3.0

B

Figure 70. Reduction in physical habitat (average weighted usable area), relative to undiverted conditions, caused by diversions into the North Waiehu and Spreckels Ditches with indicated intake capacities, Waiehu Stream near an altitude of 20 feet, Maui, Hawaiÿi. A, zero diversion into two private ÿauwai 

(ditches) near altitudes of 620 and 570 feet, South Waiehu Stream. B, Combined diversion capacity of 

0.65 million gallons per day (1 cubic foot per second) for two private ÿauwai near altitudes of 620 and 

570 feet, South Waiehu Stream. Habitat reduction computed for low-flow periods, when streamflow is 

less than or equal to the median discharge, using generalized relation between habitat and discharge. A 

ditch intake is assumed to divert at a rate up to, but not exceeding, the indicated capacity (if streamflow 

is less than the indicated capacity, then all streamflow at the ditch intake is assumed to be diverted).

116 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
10

90

100

80

70

60

50

40

30

20

10

90

100

80

70

60

50

40

30

20

LINE OF EQUAL ESTIMATED HABITAT REDUCTION

IN ÿÏAO STREAM, IN PERCENTAGE REDUCTION

RELATIVE TO UNDIVERTED LOW-FLOW 

CONDITIONS—Interval 10 percent

50

0 5 10 15 20 25 30

CAPACITY OF COMMON INTAKE FOR ÿÏAO-MÄNIANIA AND ÿÏAO-WAIKAPÜ DITCHES, ÿÏAO STREAM,

IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE, ÿÏAO STREAM, IN CUBIC FEET PER SECOND

CAPACITY OF SPRECKELS DITCH INTAKE, ÿÏAO STREAM, IN MILLION GALLONS PER DAY

35 40

0 5 10 15

CAPACITY OF COMMON INTAKE FOR ÿÏAO-MÄNIANIA AND ÿÏAO-WAIKAPÜ DITCHES, ÿÏAO STREAM,

IN MILLION GALLONS PER DAY

20 25

0

10

5

20

15

25

35

30

40

0

10

5

20

15

25

35

30

40

0

5

10

15

20

25

0

5

10

15

20

25

A

B

Figure 71. Reduction in physical habitat (average weighted usable area), relative to undiverted conditions, caused by diversions into the ÿÏao-Ma ̄niania and ÿÏao-Waikapu ̄ Ditches and Spreckels Ditch 

with indicated intake capacities, ÿÏao Stream near an altitude of 35 feet, Maui, Hawaiÿi. A, Zero diversion into a private ÿauwai (ditch) near an altitude of 650 feet. B, Diversion capacity of 0.65 million gallons per day (1 cubic foot per second) for a private ÿauwai near an altitude of 650 feet. Habitat reduction computed for low-flow periods, when streamflow is less than or equal to the median discharge, 

using generalized relation between habitat and discharge. A ditch intake is assumed to divert at a 

rate up to, but not exceeding, the indicated capacity (if streamflow is less than the indicated capacity, 

then all streamflow at the ditch intake is assumed to be diverted).

Effects of Surface-Water Diversions on Water Temperature 117
30

40

50

60

10

20

70

80

90

100

10

20

30

40

90

80

70

60

50

100

LINE OF EQUAL ESTIMATED HABITAT REDUCTION

IN WAIKAPÜ STREAM, IN PERCENTAGE REDUCTION

RELATIVE TO UNDIVERTED LOW-FLOW 

CONDITIONS—Interval 10 percent

50

0 1 2 3 4 5

CAPACITY OF SOUTH SIDE DITCH INTAKE, WAIKAPÜ STREAM, IN CUBIC FEET PER SECOND

COMBINED CAPACITY OF PRIVATE ÿAUWAI, WAIHEÿE DITCH, AND RESERVOIR 6 INTAKES, WAIKAPÜ STREAM, IN CUBIC FEET PER SECOND

COMBINED CAPACITY OF PRIVATE ÿAUWAI, WAIHEÿE DITCH, AND RESERVOIR 6 INTAKES, WAIKAPÜ STREAM, IN MILLION GALLONS PER DAY

6 7 8 9 10

0 1 2 3

CAPACITY OF SOUTH SIDE DITCH INTAKE, WAIKAPÜ STREAM, IN MILLION GALLONS PER DAY

4 5 6

0

2

1

3

4

5

6

7

9

8

10

0

1

2

3

4

5

6

0

1

2

3

4

5

6

0

1

2

3

4

5

7

6

8

9

10

A

B

Figure 72. Reduction in physical habitat (average weighted usable area), relative to undiverted conditions, caused by diversion into the South Side Ditch and combined diversions from a private ÿauwai 

(ditch) near an altitude of 560 feet, Waiheÿe Ditch, and Reservoir 6 Ditch with indicated intake capacities, Waikapü Stream near an altitude of 400 feet, Maui, Hawaiÿi. A, Zero diversion into Everett Ditch. 

B, Diversion capacity of 0.65 million gallons per day (1 cubic foot per second) for Everett Ditch. Habitat 

reduction computed for low-flow periods, when streamflow is less than or equal to the median discharge, using generalized relation between habitat and discharge. A ditch intake is assumed to divert 

at a rate up to, but not exceeding, the indicated capacity (if streamflow is less than the indicated capacity, then all streamflow at the ditch intake is assumed to be diverted).

118 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
mean temperature (16.5°C) was measured during February 

2007 at three sites in Waikapū Stream, near altitudes of 1,160 

ft, 1,080 ft, and 820 ft. The highest daily mean temperature 

(24.8°C) was measured during July 2007 in Waihe‘e River 

near an altitude of 45 ft, downstream of all diversions. Data 

from all sites indicate that daily mean temperatures were 

higher (ranging from 19.1°C to 24.8°C) during the months of 

June through September, which are part of the dry season, and 

lower (ranging from 16.5°C to 22.5°C) during the months of 

December through March, which are part of the wet season 

(figs. 73–76).

In general, stream temperatures increase in a downstream 

direction (figs. 73–76). An increase in water temperature in 

a downstream direction is caused partly by an increase in air 

temperature in a downstream direction, frictional heating, 

and exposure of the water to solar radiation, which may be 

enhanced by upstream diversion of water. An increase in water 

temperature in a downstream direction also may be related 

to inflows of warmer water from different sources, including 

natural tributaries, return flows or leakage from ditches, 

irrigation water that is returned to the stream, and possibly a 

shallow groundwater body. In some cases, stream temperatures 

may decrease in a downstream direction because of inflow of 

relatively cold water between an upstream and downstream 

measurement site (fig. 76). 

Differences in daily mean water temperatures between 

the uppermost site in a stream and the downstream sites in 

the same stream generally were larger during the months 

of June through September and smaller during the months 

of December through March (figs. 73–76), which may be 

related to reduced solar radiation during the months of 

December through March (National Renewable Energy 

Laboratory, 2009). The longitudinal temperature differences 

were reduced during periods of heavy rainfall, as indicated 

by periods of high streamflow (figs. 73, 75). The reduced 

longitudinal temperature differences during rainy periods 

may be related to factors including: (1) direct runoff of nearly 

uniform temperature entering along the length of the stream; 

(2) a smaller altitudinal air-temperature gradient during 

rainy periods; (3) a reduced effect of ditch-return flows and 

irrigation water entering the stream; and (4) increased water 

velocities and shorter traveltimes, which reduce the possibility 

for warming of water.

Waiheÿe River

Five temperature-monitoring sites were established 

in Waihe‘e River near altitudes ranging from 600 to 45 ft. 

The uppermost site near an altitude of 600 ft was about 15 

ft upstream of the left branch intake of Waihe‘e Ditch. The 

other four sites were located about 1,900, 3,800, 8,200, and 

14,000 ft downstream of the uppermost site: the site near an 

altitude of 500 ft was between the diversion intakes for Waihe‘e 

and Spreckels Ditches, and downstream of where water is 

sometimes returned to Waihe‘e River from the Waihe‘e Ditch; 

the site near an altitude of 400 ft was immediately upstream of 

the intake for Spreckels Ditch; the site near an altitude of 260 ft 

was 4,400 ft downstream of the intake for Spreckels Ditch; and 

the site near an altitude of 45 ft was about 1,500 ft upstream of 

the coast. 

During the period March through September 2007, for 

which complete records are available at all five sites, the overall 

average water temperatures were 19.5, 20.4, 21.2, 21.9, and 

22.7°C near stream altitudes of 600, 500, 400, 260, and 45 ft, 

respectively (table 24). Between altitudes of 600 and 500 ft, the 

average temperature gradient (temperature change per 1,000 

feet of stream length) during March through September 2007 

was 0.5°C per 1,000 ft; between altitudes of 500 and 400 ft, the 

average temperature gradient was 0.4°C per 1,000 ft; between 

altitudes of 400 and 260 ft, the average temperature gradient 

was 0.2°C per 1,000 ft; and between altitudes of 260 and 45 ft, 

the average temperature gradient was 0.1°C per 1,000 ft. The 

average temperature gradient between adjacent sites was greatest 

between altitudes of 600 and 500 ft, which bracket the diversion 

intakes for the Waihe‘e Ditch. Daily mean temperatures near 

an altitude of 600 ft were less than corresponding daily mean 

temperatures at all downstream sites (fig. 73). 

Downstream increases in temperature potentially 

could be reduced if no water is diverted from the stream. 

For example, during June 15–20, 2007, photographic data 

indicate that water diverted from Waihe‘e River by the 

Waihe‘e Ditch was returned to Waihe‘e River about 400 

ft downstream of the diversion intakes, and the restored 

flow continued past the lowest measurement site near an 

altitude of 45 ft. During this period, measured temperatures 

decreased by about 2–3°C, relative to the period just before 

the flow restoration, at sites downstream of where water 

was returned to Waihe‘e River (fig. 73). Also during this 

period, temperature increases between the upstream site and 

the downstream sites were reduced (fig. 73), which may be 

partly explained by the flow restoration. During June 16–19, 

2007 (flow was restored on only parts of June 15 and 20, 

2007), the average water temperatures were 19.5, 19.6, 19.9, 

20.5, and 21.2°C near stream altitudes of 600, 500, 400, 

260, and 45 ft, respectively. During the June 16–19, 2007, 

period of flow restoration, the difference between average 

water temperatures near altitudes of 45 and 600 ft was 1.7°C, 

whereas during the period March through September 2007, 

the difference was 3.2°C. 

South Waiehu Stream

Three temperature-monitoring sites were established in 

South Waiehu Stream near altitudes of 635, 555, and 290 ft, 

and one site was established in Waiehu Stream near an altitude 

of 190 ft. The uppermost site near an altitude of 635 ft was 

upstream of all known existing diversions. The other three 

sites were located 1,600, 7,300, and 9,600 ft downstream 

of the uppermost site: the site near an altitude of 555 ft was 

about 150 ft upstream of the Waihe‘e Ditch flume over South 

Effects of Surface-Water Diversions on Water Temperature 119
Waiehu Stream; the site near an altitude of 290 ft was about 

400 ft upstream of the diversion intake for Spreckels Ditch; 

and the site in Waiehu Stream near an altitude of 190 ft was 

downstream of all known diversions. 

During the period March through September 2007, for 

which complete records are available at all four sites, the overall 

average water temperatures were 19.9, 20.4, 21.0, and 22.2°C 

near stream altitudes of 635, 555, 290, and 190 ft, respectively 

(table 24). Between altitudes of 635 and 555 ft, the average 

temperature gradient during March through September 2007 

was 0.3°C per 1,000 ft; between altitudes of 555 and 290 ft, 

the average temperature gradient was 0.1°C per 1,000 ft; and 

between altitudes of 290 and 190 ft, the average temperature 

gradient was 0.5°C per 1,000 ft. The average temperature 

gradient between adjacent sites was greatest between altitudes of 

290 and 190 ft, which bracket the diversion intake for Spreckels 

Ditch in South Waiehu Stream. Daily mean temperatures at 

an altitude of 635 ft were less than corresponding daily mean 

temperatures at all downstream sites (fig. 74).

ÿĪao Stream

Four temperature-monitoring sites were established 

in ‘Īao Stream near altitudes of 920, 810, 740, and 580 ft. 

The two upper sites were upstream of the common intake 

for the ‘Īao-Waikapū and ‘Īao-Māniania Ditches and were 

established to evaluate the natural change in temperature 

in ‘Īao Stream. The sites near altitudes of 920 and 810 ft 

were, respectively, about 2,400 and 400 ft upstream of the 

diversion intake, and the sites near altitudes of 740 and 580 

ft were, respectively, about 500 and 4,000 ft downstream of 

the intake. 

To evaluate the natural change in temperature in ‘Īao 

Stream upstream of the common intake for the ‘Īao-Waikapū 

and ‘Īao-Māniania Ditches, temperature sensors were placed 

near stream altitudes of 920 and 810 ft. On average, daily 

mean temperatures at the downstream site were about 0.1°C 

warmer than at the upstream site, located about 2,000 ft 

upstream. This natural increase in temperature in ‘Īao Stream 

Table 24. Temperature-monitoring sites, Na− Wai ÿEha−, Maui, Hawaiÿi.

[—, more than one missing daily mean value during the period March through September, 2007; ft, feet]

Site USGS site no. Altitude, 

in feet

Average 

temperature, 

in degrees 

Celsius1

Average diurnal 

temperature 

variation, in

degrees Celsius2

Description

Waiheÿe River

1 205611156324601 600 19.5 1.5 15 feet upstream of Waiheÿe Ditch intakes

2 205625156323401 500 20.4 1.6 1,900 feet downstream of Waiheÿe Ditch intakes

3 205632156322001 400 21.2 2.2 50 feet upstream of Spreckels Ditch intake

4 205635156313901 260 21.9 1.4 4,400 feet downstream of Spreckels Ditch intake

5 205644156304401 45 22.7 2.9 1,500 feet upstream of coast

South Waiehu Stream

1 205427156313101 635 19.9 1.0 upstream of private ÿauwai intakes

2 205433156311501 555 20.4 1.4 downstream of private ÿauwai intakes

3 205439156303401 290 21.0 1.7 400 feet upstream of Spreckels Ditch intake

4 (Waiehu Stream) 205455156302301 190 22.2 2.4 downstream of confluence of North and South 

Waiehu Streams

ÿÏao Stream

1 205250156324401 920 19.8 2.2 2,400 feet upstream of ÿÏao-Waikapü Ditch intake3

2 205255156322401 810 19.9 2.2 400 feet upstream of ÿÏao-Waikapü Ditch intake3

3 205256156321601 740 20.4 1.0 500 feet downstream of ÿÏao-Waikapü Ditch intake3

4 205304156314401 580 21.2 2.3 4,000 feet downstream of ÿÏao-Waikapü Ditch intake3

Waikapü Stream

1 205121156321501 1,160 19.2 1.1 700 feet upstream of South Side Ditch intake

2 205123156320501 1,080 — — 800 feet downstream of South Side Ditch intake

3 205126156315501 1,020 18.9 1.1 600 feet downstream of unnamed tributary inflow

4 205120156312801 820 19.5 1.5 1,300 feet downstream of Everett Ditch intake

5 205125156304801 560 20.3 2.0 upstream of private ÿauwai intake

1

Average water temperature during March through September, 2007.

2

Average difference between daily maximum and minimum water temperatures during March through September, 2007.

3

The ÿÏao-Waikapü Ditch shares a common intake with the ÿÏao-Mäniania Ditch.

120 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Figure 73. Daily mean discharge and water temperatures, Waiheÿe River, Maui, Hawaiÿi. A, Daily mean discharge at stream-gaging station 16614000. B, Daily mean water temperatures between altitudes of 600 and 

45 feet. C, Daily mean temperature difference between an altitude of 600 feet (upstream of the Waiheÿe Ditch 

intakes) and downstream sites. A positive temperature difference indicates water temperature at downstream 

site is greater than water temperature at an altitude of 600 feet.

500

400

260

45

ALTITUDE OF DOWNSTREAM SITE, IN FEET

600

500

400

260

45

STREAM ALTITUDE, IN FEET

15

16

17

18

10

100

1,000

19

21

22

23

24

20

25

0

1

2

3

DAILY MEAN WATER TEMPERATURE,

IN DEGREES CELSIUS

DAILY MEAN TEMPERATURE DIFFERENCE BETWEEN

AN ALTITUDE OF 600 FEET AND DOWNSTREAM SITES,

IN DEGREES CELSIUS

DAILY MEAN DISCHARGE AT STREAM-GAGING

STATION 16614000, IN CUBIC FEET PER SECOND

4

5

SEPT OCT NOV DEC JAN FEB MAR APR MAY

2006 2007

JUNE JULY AUG SEPT OCT

10

100

DAILY MEAN DISCHARGE AT STREAM-GAGING

STATION 16614000, IN MILLION GALLONS PER DAY

C

A

B

Effects of Surface-Water Diversions on Water Temperature 121
in a downstream direction could be affected by inflow of 

colder groundwater between the two measurement sites (the 

sites are in the area of dike-impounded groundwater, where 

groundwater levels are expected to be high), although no 

measurements of streamflow gain between these two sites 

were made during the study. 

During the period March through September 2007, for 

which nearly complete records are available at all four sites 

(the site at an altitude of 810 ft has one missing daily mean 

temperature value), the overall average water temperatures 

were 19.8, 19.9, 20.4, and 21.2°C near stream altitudes of 

920, 810, 740, and 580 ft, respectively (table 24). Between 

altitudes of 920 and 810 ft, the average temperature gradient 

during March through September 2007 was 0.05°C per 

1,000 ft; between altitudes of 810 and 740 ft, the average 

temperature gradient was 0.6°C per 1,000 ft; and between 

altitudes of 740 and 580 ft, the average temperature gradient 

was 0.2°C per 1,000 ft. The average temperature gradient 

between adjacent sites was greatest between altitudes of 

810 and 740 ft, which bracket the diversion intake for the 

‘Īao-Waikapū and ‘Īao-Māniania Ditches. Daily mean 

temperatures at an altitude of 920 ft generally were less than 

corresponding daily mean temperatures at the downstream 

sites, although the daily mean temperature near an altitude of 

920 ft was sometimes higher than that near an altitude of 740 

ft (fig. 75), and this condition may be related to diversion of 

water (see following section entitled “Diurnal Temperature 

Variations”).

Waikapu  ̄ Stream

Five temperature-monitoring sites were established in 

Waikapū Stream near altitudes ranging from 1,160 to 560 

ft. The uppermost site near an altitude of 1,160 ft was about 

700 feet upstream of the intake for the South Side Ditch. 

The other four sites were located about 1,500, 2,600, 5,900, 

555

290

190 (Waiehu Stream)

ALTITUDE OF DOWNSTREAM SITE, IN FEET

635

555

290

190 (Waiehu Stream)

STREAM ALTITUDE, IN FEET

15

16

17

18

19

21

22

23

24

20

25

0

1

2

3

DAILY MEAN WATER TEMPERATURE,

IN DEGREES CELSIUS

DAILY MEAN TEMPERATURE DIFFERENCE BETWEEN

AN ALTITUDE OF 635 FEET AND DOWNSTREAM SITES,

IN DEGREES CELSIUS

4

5

SEPT OCT NOV DEC JAN FEB MAR APR MAY

2006 2007

JUNE JULY AUG SEPT OCT

A

B

Figure 74. Daily mean water temperatures between altitudes of 635 and 190 feet, South Waiehu Stream, 

Maui, Hawaiÿi. A, Daily mean water temperatures. B, Daily mean temperature difference between an altitude of 635 feet (upstream of diversions) and downstream sites. A positive temperature difference indicates water temperature at downstream site is greater than water temperature at an altitude of 635 feet.

122 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
and 11,000 ft downstream of the uppermost site: the site 

near an altitude of 1,080 ft was about 800 ft downstream of 

the intake for the South Side Ditch; the site near an altitude 

of 1,020 ft was about 600 ft downstream of the confluence 

of Waikapū Stream and an unnamed tributary; the site near 

an altitude of 820 ft was about 1,300 ft downstream of the 

intake for the Everett Ditch; and the site near an altitude of 

560 ft was about 100 ft upstream of the intake for an existing 

community ‘auwai.

During the period March through September 2007, for 

which complete records are available at four of the five sites, 

the overall average water temperatures were 19.2, 18.9, 19.5, 

and 20.3°C near stream altitudes of 1,160, 1,020, 820, and 

560 ft, respectively (table 24). Between altitudes of 1,160 

and 1,020 ft, the average temperature gradient during March 

through September 2007 was −0.1°C per 1,000 ft; between 

altitudes of 1,020 and 820 ft, the average temperature 

gradient was 0.2°C per 1,000 ft; and between altitudes of 

820 and 560 ft, the average temperature gradient was 0.2°C 

per 1,000 ft. The average temperature gradient was greatest 

downstream of the diversion intake for the South Side Ditch 

and also downstream of the unnamed tributary that enters 

the north side (left side as viewed downstream) of Waikapū 

Stream near an altitude of 1,050 ft.

Daily mean temperatures near an altitude of 1,160 

ft were less than corresponding daily mean temperatures 

near an altitude of 560 ft and generally were less than 

daily mean temperatures near an altitude of 820 ft (fig. 76). 

However, daily mean temperatures near an altitude of 1,160 

ft commonly were higher than daily mean temperatures 

near an altitude of 1,020 ft (fig. 76). Stream temperatures 

decreased in a downstream direction between altitudes 

of 1,160 and 1,020 ft because of inflow of relatively cold 

water from the unnamed tributary between the upstream and 

downstream sites. 

Diurnal Temperature Variations

Because exposure to lethal temperatures for short 

durations, in some cases less than 30 minutes (Hathaway, 

1978), can cause death in native aquatic species, maximum 

and minimum daily temperatures were considered. 

Temperatures vary on a diurnal basis because of diurnal 

variations in energy (in the form of solar radiation and 

longwave radiation) received in the stream valleys. During 

daytime hours, incoming solar radiation causes stream 

temperatures to increase, whereas during the nighttime, 

loss of infrared energy from the surface causes stream 

temperatures to decrease. During the periods when measured 

temperatures were available, daily maximum temperatures 

did not exceed 27°C and daily minimum temperatures did 

not drop below 15°C at any of the study sites (figs. 77–80). 

At all of the study sites, daily maximum temperatures 

remained below the upper-lethal-temperature limits for 

native aquatic species (Hathaway, 1978), as well as below 

the temperature (27°C) that favors Pythium rot of taro 

(Ooka, 1994). In general, maximum temperatures occurred 

during the afternoon hours (between about 1:00 p.m. and 

6:00 p.m.) and minimum temperatures occurred in the 

morning hours (between about 3:00 a.m. and 8:00 a.m.). 

Differences between measured daily maximum and minimum 

temperatures generally are greatest at the lowest site and 

least at the highest site on a stream and were enhanced 

during warm, dry periods and reduced during cool, wet 

periods (fig. 77).

Waiheÿe River

During the period March through September 2007, 

the average differences between measured daily maximum 

and minimum temperatures were 1.5, 1.6, 2.2, 1.4, and 2.9 

°C near stream altitudes of 600, 500, 400, 260, and 45 ft, 

respectively (table 24). During low-flow conditions, surface 

flows past the Waihe‘e Ditch and Spreckels Ditch diversion 

intakes in Waihe‘e River were typically zero when available 

streamflow did not exceed the capacity of the intakes. As a 

result, at some reaches downstream of diversions, standing 

water and low flows during dry-weather conditions were 

sustained mainly by local groundwater discharge. For sites 

near sources of groundwater discharge, diurnal temperature 

variations may be small because temporal variations in 

groundwater temperatures are relatively small. The site 

near an altitude of 260 ft has a smaller average diurnal 

temperature variation than the upstream sites, which may 

reflect a local source of groundwater input to the stream that 

is the main source of water during low-flow conditions when 

water was being diverted upstream. Flow past the lowest 

measurement site near an altitude of 45 ft is sustained 

mainly by return of irrigation water to Waihe‘e River 

upstream of this site and downstream of the site near an 

altitude of 260 ft. 

South Waiehu Stream

During the period March through September 2007, the 

average differences between measured daily maximum and 

minimum temperatures were 1.0, 1.4, 1.7, and 2.4°C near 

stream altitudes of 635, 555, 290, and 190 ft, respectively (table 

24). The average difference between measured daily maximum 

and minimum temperatures increases in a downstream direction. 

ÿĪao Stream

During the period March through September 2007, the 

average differences between measured daily maximum and 

minimum temperatures were 2.2, 2.2, 1.0, and 2.3°C near 

stream altitudes of 920, 810, 740, and 580 ft, respectively (table 

Effects of Surface-Water Diversions on Water Temperature 123
810

740

580

ALTITUDE OF DOWNSTREAM SITE, IN FEET

920

810

740

580

STREAM ALTITUDE, IN FEET

15

16

17

18

10

100

1,000

19

21

22

23

24

20

25

-1

0

1

2

DAILY MEAN WATER TEMPERATURE,

IN DEGREES CELSIUS

DAILY MEAN TEMPERATURE DIFFERENCE BETWEEN

AN ALTITUDE OF 920 FEET AND DOWNSTREAM SITES,

IN DEGREES CELSIUS

DAILY MEAN DISCHARGE AT STREAM-GAGING

STATION 16604500, IN CUBIC FEET PER SECOND

3

4

SEPT OCT NOV DEC JAN FEB MAR APR MAY

2006 2007

JUNE JULY AUG SEPT OCT

10

100

DAILY MEAN DISCHARGE AT STREAM-GAGING

STATION 16604500, IN MILLION GALLONS PER DAY

A

B

C

Figure 75. Daily mean discharge and water temperatures, ÿÏao Stream, Maui, Hawaiÿi. A, Daily mean discharge 

at stream-gaging station 16604500. B, Daily mean water temperatures between altitudes of 920 and 580 feet. 

C, Daily mean temperature difference between an altitude of 920 feet (upstream of the ÿÏao-Waikapü and ÿÏaoMa ̄niania Ditch intakes) and downstream sites. A positive temperature difference indicates water temperature at 

downstream site is greater than water temperature at an altitude of 920 feet.

124 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
1,080

1,020

820

560

ALTITUDE OF DOWNSTREAM SITE, IN FEET

1,160

1,080

1,020

820

560

STREAM ALTITUDE, IN FEET

15

16

17

18

19

21

22

23

24

20

25

-2

-1

0

1

DAILY MEAN WATER TEMPERATURE,

IN DEGREES CELSIUS

DAILY MEAN TEMPERATURE DIFFERENCE BETWEEN

AN ALTITUDE OF 1,160 FEET AND DOWNSTREAM SITES,

IN DEGREES CELSIUS

2

3

SEPT OCT NOV DEC JAN FEB MAR APR MAY

2006 2007

JUNE JULY AUG SEPT OCT

A

B

Figure 76. Daily mean water temperatures between altitudes of 1,160 and 560 feet, Waikapu ̄ Stream, Maui, 

Hawaiÿi. A, Daily mean water temperatures. B, Daily mean temperature difference between an altitude of 

1,160 feet (upstream of the South Side Ditch intake) and downstream sites. A positive temperature difference 

indicates water temperature at downstream site is greater than water temperature at an altitude of 1,160 feet.

24). During low-flow conditions, surface flows in ‘Īao Stream 

past the intake for the ‘Īao-Waikapū and ‘Īao-Māniania Ditches 

were typically zero when available streamflow did not exceed 

the capacity of the intake. As a result, low flows immediately 

downstream of the intake during dry-weather conditions were 

sustained mainly by local groundwater discharge. The site near 

an altitude of 740 ft has a smaller average diurnal temperature 

variation than the upstream sites, which may reflect a local 

source of groundwater input to the stream that is the main 

source of water during low-flow periods when water was being 

diverted upstream. 

Waikapu ̄ Stream

During the period March through September 2007, the 

average differences between measured daily maximum and 

minimum temperatures were 1.1, 1.1, 1.5, and 2.0°C near stream 

altitudes of 1,160, 1,020, 820, and 560 ft, respectively (table 

24). The average difference between measured daily maximum 

and minimum temperatures generally increases in a downstream 

direction, although the average differences at 1,160 and 1,020 

ft are the same, possibly because of the inflow of relatively cold 

water from an unnamed tributary between the two sites. 

Effects of Surface-Water Diversions on Water Temperature 125
600

260

45

STREAM ALTITUDE, IN FEET

10

100

1,000

DISCHARGE AT STREAM-GAGING STATION 16614000,

IN CUBIC FEET PER SECOND

18

20

22

24

26

28

WATER TEMPERATURE, IN DEGREES CELSIUS

0

1

2

3

DIFFERENCE BETWEEN DAILY MAXIMUM AND MINIMUM

WATER TEMPERATURES, IN DEGREES CELSIUS

4

6

5

1 15 20 25 5130 10 15 20 25 30

AUGUST 2007 SEPTEMBER 2007

5 10

10

100

DISCHARGE AT STREAM-GAGING STATION 16614000,

IN MILLION GALLONS PER DAY

A

B

C

Figure 77. Discharge and water temperatures during August and September, 2007, Waiheÿe River, Maui, Hawaiÿi. 

A, Discharge at stream-gaging station 16614000. B, Water temperatures (measured at 15-minute intervals) 

between altitudes of 600 and 45 feet. C, Difference between daily maximum and minimum water temperatures.

126 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
635

290

190 (Waiehu Stream)

STREAM ALTITUDE, IN FEET

18

20

22

24

26

28

WATER TEMPERATURE, IN DEGREES CELSIUS

0

1

2

3

DIFFERENCE BETWEEN DAILY MAXIMUM AND MINIMUM

WATER TEMPERATURES, IN DEGREES CELSIUS

4

6

5

1 15 20 25 5130 10 15 20 25 30

AUGUST 2007 SEPTEMBER 2007

5 10

A

B

Figure 78. Water temperatures during August and September, 2007, South Waiehu Stream, Maui, Hawaiÿi. 

A, Water temperatures (measured at 15-minute intervals) between altitudes of 635 and 190 feet. B, Difference between daily maximum and minimum water temperatures.

Effects of Surface-Water Diversions on Water Temperature 127
920

740

580

STREAM ALTITUDE, IN FEET

10

100

1,000

10

100

DISCHARGE AT STREAM-GAGING STATION 16604500,

IN CUBIC FEET PER SECOND

DISCHARGE AT STREAM-GAGING STATION 16604500,

IN MILLION GALLONS PER DAY

18

20

22

24

26

28

WATER TEMPERATURE, IN DEGREES CELSIUS

0

1

2

3

DIFFERENCE BETWEEN DAILY MAXIMUM AND MINIMUM

WATER TEMPERATURES, IN DEGREES CELSIUS

4

6

5

1 15 20 25 5130 10 15 20 25 30

AUGUST 2007 SEPTEMBER 2007

5 10

A

B

C

Figure 79. Discharge and water temperatures during August and September, 2007, ÿĪao Stream, Maui, Hawaiÿi. 

A, Discharge at stream-gaging station 16604500. B, Water temperatures (measured at 15-minute intervals) 

between altitudes of 920 and 580 feet. C, Difference between daily maximum and minimum water temperatures.

128 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
1,160

820

560

STREAM ALTITUDE, IN FEET

15

17

19

21

23

25

WATER TEMPERATURE, IN DEGREES CELSIUS

0

1

2

3

DIFFERENCE BETWEEN DAILY MAXIMUM AND MINIMUM

WATER TEMPERATURES, IN DEGREES CELSIUS

4

6

5

1 15 20 25 5130 10 15 20 25 30

AUGUST 2007 SEPTEMBER 2007

5 10

A

B

Figure 80. Water temperatures during August and September, 2007, Waikapu ̄ Stream, Maui, Hawaiÿi. A, 

Water temperatures (measured at 15-minute intervals) between altitudes of 1,160 and 560 feet. B, Difference between daily maximum and minimum water temperatures.

Summary

The dependable flow of water provided by Waihe‘e River, 

Waiehu Stream, ‘Īao Stream, and Waikapū Stream, collectively 

known as Nā Wai ‘Ehā (“The Four Streams”), made it possible 

for widespread agricultural activities to flourish in the eastern 

part of West Maui, Hawai‘i. The streams of the Nā Wai ‘Ehā 

area flow in their upper reaches even during extended dryweather conditions because of persistent groundwater discharge 

to the streams. The lower reaches of these streams lose water 

by infiltration into the streambed, which may contribute to 

groundwater recharge. Surface water in the Nā Wai ‘Ehā area 

traditionally supported large areas of kalo (taro) cultivation 

for Native Hawaiians. Starting in the 19th century, large-scale 

sugarcane plantations began to dominate the landscape in the Nā 

Wai ‘Ehā area. Before 1970, an average of about 67 Mgal/d was 

diverted, mainly for sugarcane irrigation, from Waihe‘e River, 

Waiehu Stream, ‘Īao Stream, and Waikapū Stream. In 1988, 

Wailuku Sugar Company, the main user of the diverted water at 

the time, shut down operations. As of 2009, water continued to 

be diverted from streams in the Nā Wai ‘Ehā area for sugarcane 

irrigation in central Maui by Hawaiian Sugar and Commercial 

Company, for municipal and domestic uses, golf-course and 

landscape irrigation, maintaining pastures for cattle grazing, and 

other agricultural uses. 

Daily mean discharge data from a continuous-record 

stream-gaging station in Waihe‘e River (16410000) near an 

altitude of 605 ft, upstream of existing diversions, indicate that 

the long-term median (Q50) discharge was 34 Mgal/d (52 ft3

/s) 

during climate years 1984–2007. Seepage-run measurements 

were used to estimate the minimum flow near an altitude of 605 

ft necessary for Waihe‘e River to maintain continuous flow to 

the ocean. A minimum flow of about 1 Mgal/d (1.6 ft3/s) near an 

altitude of 605 ft is needed to initiate flow near the coast at an 

altitude of 45 ft, assuming no diversions exist. This minimum 

flow estimate of 1 Mgal/d (1.6 ft3

/s) for Waihe‘e River is much 

less than the minimum recorded flow of 14 Mgal/d (22 ft3

/s) 

during climate years 1984–2007 near an altitude of 605 ft. Thus, 

during climate years 1984–2007, Waihe‘e River would have 

Summary 129
flowed continuously to the coast at all times if no diversions 

existed.

Daily mean discharge data from ‘Īao Stream (gaging 

station 16604500) near an altitude of 780 ft, upstream of existing 

diversions, indicate that the long-term median discharge was 

25 Mgal/d (39 ft3/s) during climate years 1984–2007. For ‘Īao 

Stream, a minimum flow of about 5.2 Mgal/d (8.1 ft3/s) near an 

altitude of 780 ft is needed to initiate flow near the coast at an 

altitude of 35 ft, assuming no diversions exist. This minimum 

flow estimate of 5.2 Mgal/d (8.1 ft3

/s) for ‘Īao Stream is less 

than the minimum recorded flow of 6.1 Mgal/d (9.4 ft3/s) during 

climate years 1984–2007 near an altitude of 780 ft. Thus, during 

climate years 1984–2007, ‘Īao Stream would have flowed 

continuously to the coast at all times if no diversions existed.

Active continuous-record stream-gaging stations are not 

available for Waiehu or Waikapū Streams, although historical 

data from the early part of the 20th century are available to 

estimate the low-flow characteristics of these streams during 

climate years 1984–2007. For North Waiehu Stream near an 

altitude of 880 ft, upstream of existing diversions, the estimated 

median discharge is 3.2 Mgal/d (4.9 ft3/s). For South Waiehu 

Stream near an altitude of 870 ft, upstream of existing diversions, 

the estimated median discharge is 3.2 Mgal/d (5.0 ft3/s). For 

Waiehu Stream, a minimum flow of 1.3 Mgal/d (2.1 ft3

/s) near 

an altitude of 880 ft in North Waiehu Stream, corresponding to 

a flow of 1.1 Mgal/d (1.7 ft3/s) in South Waiehu Stream near an 

altitude of 870 ft, is needed to initiate flow near the coast at an 

altitude of 20 ft, assuming no diversions exist. The minimum 

flow estimate of 1.3 Mgal/d (2.1 ft3/s) for North Waiehu Stream 

is between the estimated Q95 and Q99 flows during climate years 

1984–2007 near an altitude of 880 ft. Thus, during climate years 

1984–2007, Waiehu Stream would have flowed continuously to 

the coast at least 95 percent of the time if no diversions existed.

For Waikapū Stream near an altitude of 1,160 ft, the 

estimated median undiverted discharge is 4.3 Mgal/d (6.6 ft3/s) 

for climate years 1984–2007. A minimum flow of about 6.8 

Mgal/d (11 ft3/s) near an altitude of 1,160 ft is needed to initiate 

flow near the coast at an altitude of 10 ft, assuming no diversions 

exist. This minimum flow estimate of 6.8 Mgal/d (11 ft3

/s) for 

Waikapū Stream is greater than the estimated median flow. Thus, 

during climate years 1984–2007, Waikapū Stream would have 

flowed continuously to the coast less than half of the time if no 

diversions existed. 

Currently, the main diversions from Waihe‘e River are 

the Waihe‘e and Spreckels Ditches, with intakes near altitudes 

of about 600 and 400 ft, respectively. In addition, the Field 

1 diversion intake and dam exist near an altitude of 260 ft in 

Waihe‘e River. The North Waiehu Ditch has an intake near 

an altitude of 880 ft and is the only existing diversion from 

North Waiehu Stream. Three known diversions exist on South 

Waiehu Stream: two ‘auwai (ditches) for private use with 

intakes near altitudes of 620 ft (north side of stream) and 

570 ft (south side of stream) and the Spreckels Ditch with 

an intake near an altitude of 270 ft. The main diversions in 

‘Īao Stream are the ‘Īao-Waikapū and ‘Īao-Māniania Ditches, 

which share a common intake near an altitude of 780 ft, and 

the Spreckels Ditch with an intake in a concrete-lined channel 

near an altitude of 250 ft. A small private intake exists near an 

altitude of 650 ft and diverts water through a pipe for use on 

the south side of ‘Īao Stream. Five known diversion intakes 

exist on Waikapū Stream: (1) the South Side Ditch is the most 

upstream diversion, with an intake near an altitude of 1,120 

ft; (2) the Everett Ditch intake is near an altitude of 900 ft; (3) 

a private, community ‘auwai diverts water near an altitude of 

560 ft; (4) the Waihe‘e Ditch intake is near an altitude of 440 

ft; and (5) the Reservoir 6 intake is near an altitude of 410 ft. 

Existing diversions are capable of diverting all or nearly 

all of the dry-weather flows of these streams, leaving some 

downstream reaches completely dry. Hourly photographs 

collected during 2006–2008 indicate that some stream reaches 

downstream of diversions are dry more than 50 percent of 

the time. Many of these reaches would be perennial or nearly 

perennial in the absence of diversions. 

For streams in which all of the dry-weather flow is diverted, 

infiltration of water in losing reaches downstream of diversions 

may be reduced to zero during dry-weather conditions. For 

natural, undiverted conditions, many of these dry stream reaches 

would not exist. Thus, these dry stream reaches represent a 

potential loss of recharge to the underlying groundwater body. 

Seepage-run measurements were used to estimate the effects 

of surface-water diversions on recharge beneath the stream 

channels during low-flow conditions, assuming none of the 

diverted water is returned to the streams. For Waihe‘e River, 

existing diversions by the Waihe‘e and Spreckels Ditches reduce 

potential groundwater recharge by 1.7 Mgal/d (2.7 ft3

/s). For 

Waiehu Stream, existing diversions by the North Waiehu Ditch 

and Spreckels Ditch reduce potential groundwater recharge by 

about 1 Mgal/d (0.65 ft3/s), even if no water is diverted by each 

of two private ‘auwai on South Waiehu Stream. For ‘Īao Stream, 

existing diversions by the ‘Īao-Waikapū and ‘Īao-Māniania 

Ditches and Spreckels Ditch reduce potential groundwater 

recharge by about 4.8 Mgal/d (7.4 ft3/s). For Waikapū Stream, 

existing diversions by the South Side Ditch, private ‘auwai with 

intake near an altitude of 560 ft, Waihe‘e Ditch, and Reservoir 

6 Ditch reduce potential groundwater recharge by about 4 

Mgal/d (6 ft3

/s), even if no water is diverted by the Everett Ditch. 

Families of curves were developed for each stream to show 

the relation between surface-water diversion intake capacities 

and recharge reduction. These curves can be used to assist 

with water-management decisions by identifying diversion 

intake capacities that will lead to an acceptable reduction in 

groundwater recharge.

The streams in the Nā Wai ‘Ehā area provide habitat for 

native stream fauna. Snorkel surveys at selected stream reaches 

during 2008 identified the presence of native fauna in each of the 

Nā Wai ‘Ehā streams. Native fauna observed in the Nā Wai ‘Ehā 

streams include the endemic mountain shrimp, ‘ōpaekala‘ole 

(Atyoida bisulcata); endemic gobies ‘o‘opu ‘alamo‘o (Lentipes 

concolor) and ‘o‘opu nōpili (Sicyopterus stimpsoni); the 

indigenous goby ‘o‘opu nākea (Awaous guamensis); and an 

130 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
endemic eleotrid, ‘o‘opu ‘akupa (Eleotris sandwicensis). 

The amphidromous life cycle of native stream fauna requires 

unimpeded access to and from the ocean. 

Changes in streamflow may affect the quantity and quality 

of physical habitat used by native stream fauna. For this study, 

the effects of changes in streamflow on physical habitat, in 

terms of weighted usable area (WUA) were evaluated using the 

Physical Habitat Simulation System (PHABSIM) approach. 

Measurements of microhabitat under different flow conditions 

were combined with habitat-suitability criteria modified from 

those developed for streams in northeast Maui. In general, data 

indicate that physical habitat increases monotonically with 

discharge up to the median natural discharge. A generalized 

relation between physical habitat and discharge developed for 

this study indicates that if diversions reduce streamflow to 20 

percent of the natural, undiverted Q70 discharge (discharge that 

is equaled or exceeded 70 percent of the time), which is an 

indicator of median base-flow conditions, then habitat will be 

reduced by about 33 percent; if diversions reduce streamflow to 

50 percent of the natural, undiverted Q70 discharge, habitat will 

be reduced by about 16 percent. 

To evaluate the effects of existing surface-water diversions 

on physical habitat during low-flow conditions, the generalized 

relation between habitat and discharge was used in conjunction 

with estimates of streamflow for different diversion intake 

capacities, assuming none of the diverted water is returned to 

the stream. For Waihe‘e River near an altitude of 45 ft, existing 

diversions by Waihe‘e and Spreckels Ditches reduce physical 

habitat by 100 percent during low-flow periods. For Waiehu 

Stream near an altitude of 20 ft, existing diversions by the North 

Waiehu Ditch and Spreckels Ditch reduce physical habitat by 

more than 60 percent during low-flow periods if no water is 

diverted by each of two private ‘auwai on South Waiehu Stream. 

For ‘Īao Stream near an altitude of 35 ft, existing diversions 

by the ‘Īao-Waikapū and ‘Īao-Māniania Ditches and Spreckels 

Ditch reduce physical habitat by 100 percent during low-flow 

periods. For Waikapū Stream near an altitude of 400 ft, existing 

diversions by the South Side Ditch, private ‘auwai with intake 

near an altitude of 560 ft, Waihe‘e Ditch, and Reservoir 6 Ditch 

reduce physical habitat by more than 90 percent during low-flow 

periods if no water is diverted by the Everett Ditch. Families of 

curves were developed for sites near the coast on each stream 

to show the relation between surface-water diversion intake 

capacities and habitat reduction. These curves can be used to 

assist with water-management decisions by identifying diversion 

intake capacities that will lead to an acceptable reduction in 

physical habitat.

Stream temperature is a factor that potentially could 

affect the abundance and distribution of native aquatic 

species and wetland-taro production. The upper-lethaltemperature limits for native aquatic species generally 

range from about 35°C to 40°C. Wetland-taro agriculture 

commonly is dependent on surface water with temperatures 

that do not exceed about 27°C to 29°C. During the period 

from September 2006 to October 2007, water temperatures 

immediately upstream of all diversions and at selected 

downstream sites were recorded every 15 minutes. Exposure 

to lethal temperatures for short durations, in some cases 

less than 30 minutes, can cause death in native aquatic 

species. During the periods when measured temperatures 

were available, daily maximum temperatures did not exceed 

27°C and daily minimum temperatures did not drop below 

15°C at any of the study sites. At all of the study sites, daily 

maximum temperatures remained below the upper-lethaltemperature limits for native aquatic species, as well as below 

the temperature that favors Pythium rot of taro, although 

temperatures were not measured in reaches that sometimes 

were dry.

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136 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Appendix A. Surface-Water Diversions

As of 2009, three known diversions existed on Waihe‘e 

River, one on North Waiehu Stream, three on South Waiehu 

Stream, three on ‘Īao Stream, and five on Waikapū Stream. 

Each of these diversions is described briefly in this appendix. 

Historically, additional diversions existed on each stream, and 

those that have been mapped or documented also are described 

briefly. 

Waiheÿe River

Silva (1962, p. 14) describes a “broad and deep ditch four 

miles long” that was dug in 1866 to bring water to Waihe‘e 

Plantation, although the locations of the intake and ditch are 

not known. A map from 1868 (Lewers Plantation, 1868) shows 

what appear to be two ditches that divert water from the south 

side of Waihe‘e River, and the upstream diversion may be 

the 1866 ditch that Silva (1962) described. A dam and what 

appears to be a ditch shown downstream of Huluhulupueo 

Stream (near the location of the current intake of Spreckels 

Ditch) is indicated on a Government Survey map from 1875 

of the Waihe‘e area (Gay, 1875) and also may be related to 

the 1866 ditch that Silva (1962) described. Martin and Pierce 

(1913) show locations of Waihe‘e and Spreckels Ditches and 

two smaller, unnamed ditches that diverted water from Waihe‘e 

River (fig. A1). Martin and Pierce (1913, p. 257) measured 

discharges in the “Native” (south side) and “Kapuna” (north 

side) Ditches that diverted water from Waihe‘e River, and these 

may be the two unnamed ditches (fig. A1). 

Currently (2009), the main diversions from Waihe‘e 

River are the Waihe‘e and Spreckels Ditches, with intakes 

near altitudes of 600 and 400 ft, respectively (fig. 7). 

Spreckels Ditch was constructed in 1882 and Waihe‘e Ditch 

was completed in 1907 (Silva, 1962). These ditches currently 

are maintained by Wailuku Water Company, LLC (WWC) 

with assistance from Hawaiian Sugar and Commercial 

Company (HC&S). The Field 1 diversion ditch is much 

smaller than either Waihe‘e Ditch or Spreckels Ditch and has 

an intake near an altitude of 260 ft (fig. 7). 

The original intake for Waihe‘e Ditch was near an 

altitude of 650 ft. The 10.62-mile-long Waihe‘e Ditch system 

originally consisted of 22 tunnels, varying in length from 155 

to 2,246 ft, 39 flumes totaling 2,764 ft, 1,253 ft of pipelines, 

and 35,549 ft of open ditch (Thrum, 1908). Construction 

of a new intake for the Waihe‘e Ditch was started in 1935 

(Silva, 1962). Currently (2009), the Waihe‘e Ditch has two 

intake grates in Waihe‘e River in a reach that is bifurcated by 

an island. The intake grates are near the crests of dams and 

consist of parallel steel bars roughly aligned in the direction 

of flow. Open spaces between bars are about 0.15 ft wide and 

3 to 7 ft long (in the direction of flow). The intake grate for 

the right (south) branch of Waihe‘e River stretches about 25 

ft across the entire low-flow channel and has 74 openings 

between steel bars and at the grate edges (fig. A2). The intake 

grate for the left (north) branch of Waihe‘e River stretches 

about 44 ft across the entire low-flow channel, with 121 

openings between steel bars and at the grate edges (fig. A2). 

Water that enters the intake grates drains into a collection 

sump and flows by gravity into the ditch system. The Waihe‘e 

Ditch intakes have a combined design capacity of 60 Mgal/d, 

although a downstream control gate limits flow in the ditch to 

about 40 Mgal/d (Suzuki, 2007). 

The intake for Spreckels Ditch (fig. A3) is located near 

the right (south) edge of Waihe‘e River and on the upstream 

side of a dam that stretches across the entire low-flow channel 

(fig. A4). The intake gate for Spreckels Ditch is about 6.5 ft 

wide, although only the right half of the gate is currently (2009) 

open to accept water. The Spreckels Ditch intake in Waihe‘e 

River has a design capacity of 30 Mgal/d, although a control 

gate limits flow in the ditch to about 12 Mgal/d (Suzuki, 2007). 

About 6 Mgal/d of the water diverted by the Waihe‘e Ditch 

commonly discharges into the Spreckels Ditch (Suzuki, 2007), 

about 2,000 ft downstream of the Spreckels Ditch intake. 

The Field 1 diversion intake and dam exists near an 

altitude of 260 ft. In its recent (2009) configuration, the Field 

1 diversion intake gate opening is about 1.7 ft wide and 1.2 ft 

high (fig. A5), but the capacity of the intake is unknown. The 

ditch associated with the Field 1 intake is on the north side of 

Waihe‘e River and currently (2009) also receives water from 

Spreckels Ditch through a pipeline. 

Waiehu Stream

A map from 1868 of the Waiehu area (Lewers Plantation, 

1868) shows what appears to be the North Waiehu Ditch that 

starts in North Waiehu Stream and a second ditch that either 

terminates or starts in North Waiehu Stream near the current 

location of Spreckels Ditch. Martin and Pierce (1913) show 

a single diversion (North Waiehu Ditch) from North Waiehu 

Stream near an altitude of about 880 ft and a single diversion 

(South Waiehu Ditch) from South Waiehu Stream near an 

altitude of about 860 ft, although they also indicate that water 

is diverted from both North and South Waiehu Streams “for 

irrigation through several ditches at various levels” (fig. A1). 

For example, a small ditch upstream of an altitude of 870 ft 

diverted about 0.2 Mgal/d from South Waiehu Stream for 

irrigation of taro (Grover and Larrison, 1917a). In addition, 

an undated map (Wailuku Water Company, LLC, undated) 

that shows both Spreckels and Waihe‘e Ditches also shows 

two unnamed ditches that appear to start in Waiehu Stream. 

This same undated map of Waiehu also shows one unnamed 

ditch each in the valleys of North and South Waiehu Streams 

that appear to start below the level of the Waihe‘e Ditch but 

are unconnected at their upstream ends to either a stream or 

the Waihe‘e Ditch. Thus, the source of water for these two 

unnamed ditches is uncertain. 

Currently (2009), the North Waiehu Ditch (fig. 7) is 

the only known diversion from North Waiehu Stream and 

Appendix A 137
Figure A1. Historical ditch systems, West Maui, Hawaiÿi (modified from Martin and Pierce, 1913). Map projection and datum not specified on source.

0

0

1

2

2

4

3 4 5 MILES

6 8 KILOMETERS

156°40' 156°35' 156°30'

21°

20°55'

20°50'

STREAM-GAGING STATION

RAIN-GAGING STATION

EXPLANATION

138 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Figure A2. Photographs of Waiheÿe Ditch diversion intake 

near an altitude of 600 feet, Waiheÿe River, Maui, Hawaiÿi. 

A, South (right branch) intake (July 18, 2006). B, North (left 

branch) intake (July 18, 2006).

is owned and maintained by WWC. Water in North Waiehu 

Stream is diverted into North Waiehu Ditch, located on the 

left (north) side of the stream, by a 5-ft-thick dam formed 

by boulders placed across the entire low-flow channel of the 

stream (fig. A6). The dam is about 2 ft high and 20 ft wide, 

forming an extension of the downstream wall of the ditch. 

A downstream control gate is set to limit flow in the North 

Waiehu Ditch to about 1.5 Mgal/d (Suzuki, 2007). 

Three known diversions currently exist on South 

Waiehu Stream: two ‘auwai (ditches) for private use, with 

intakes near altitudes of 620 ft (north side of stream) and 

570 ft (south side of stream) (fig. A7), and the Spreckels 

Ditch, with an intake near an altitude of 270 ft (fig. A8). The 

A

B

B

direction of

ditch flow

A

Figure A3. Photographs of Spreckels Ditch diversion 

intake on the south side of Waiheÿe River near an altitude 

of 400 feet, Maui, Hawaiÿi. A, Upstream side of intake gate 

(June 8, 2006). B, Downstream side of intake gate (far 

background) with view of Spreckels Ditch in foreground 

(July 18, 2006).

Spreckels Ditch intake near an altitude of 270 ft is owned and 

maintained by HC&S and consists of an intake grate near the 

right (south) edge of the channel. The intake grate is about 

Appendix A 139
A

B

Figure A4. Photographs of dam structure for Spreckels 

Ditch diversion intake near an altitude of 400 feet, Waiheÿe 

River, Maui, Hawaiÿi. A, Typical dry weather diverted condition (August 7, 2006). B, During ditch maintenance period 

when water was temporarily restored to Waiheÿe River (June 

8, 2006).

Figure A5. Photograph of Field 1 diversion intake (viewed 

from upstream side) near an altitude of 260 feet, Waiheÿe 

River, Maui, Hawaiÿi (June 8, 2006).

4.5 ft wide and about 13 ft long (in the general direction of 

flow). The grate has 13 openings (about 0.25 ft wide) between 

parallel steel bars and at the grate edges. The capacities of the 

diversions on South Waiehu Stream are not known. Limited 

measurements indicate that (1) flow in each of the two ‘auwai 

is less than 0.5 Mgal/d and (2) the Spreckels Ditch intake 

is capable of diverting all of the low flow of South Waiehu 

Stream up to at least 1 Mgal/d. 

‘Īao Stream

A map from 1878 of the Wailuku area (Bailey, 1878) 

shows three ditches originating in ‘Īao Stream: Kalani Ditch 

(shown as “Kalamauwai” on map) on the north side, Kama 

Ditch on the south side, and an unnamed ditch on the south 

side that leads to a sugar mill (likely the Mill Stream or 

Mill Ditch). Silva (1962, p. 19) also lists these three ditches 

that diverted water from ‘Īao Stream during 1881. Kalani 

and Kama Ditches likely were originally constructed for 

the purpose of irrigating taro on the plains to the north and 

south of ‘Īao Stream (Sterling, 1998, p. 86). Sterling (1998) 

indicated that several smaller ditches also diverted water 

from ‘Īao Stream at sites farther downstream. A map from 

1882 of the Wailuku area (Monsarrat, 1882) shows two 

unnamed ditches on the north side of ‘Īao Stream and three 

ditches on the south side. One of the two ditches on the 

north side likely is the Kalani Ditch, and the other terminates 

at a reservoir a relatively short distance from ‘Īao Stream. 

The three ditches shown on the south side of ‘Īao Stream 

(Monsarrat, 1882) are (1) the Mission Ditch (likely the 

same as the Kama Ditch), which originates near an altitude 

of about 430 ft, (2) an unnamed ditch originating near an 

altitude of about 360 ft that leads to a sugar mill (likely 

Mill Stream), and (3) Kalua Ditch, which has an uncertain 

point of origin. Martin and Pierce (1913) show locations of 

Māniania (shown as “Manainai” on map, fig. A1) and Kalani 

(shown as “Kalana” on map, fig. A1) Ditches on the north 

side and Branch, Walbridge, and Kama Ditches on the south 

side of ‘Īao Stream (fig. A1). Concrete remnants that may be 

related to the intake for the Kama Ditch are still visible in the 

140 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Figure A6. Photographs of North Waiehu Ditch diversion 

intake near an altitude of 880 feet, North Waiehu Stream, 

Maui, Hawaiÿi. A, Upstream end of North Waiehu Ditch on 

the north side of North Waiehu Stream (June 29, 2006). B, 

Boulder and cobble dam that diverts most of flow in North 

Waiehu Stream (June 29, 2006). Arrows indicate general 

direction of flow.

A

B

ditch flow

ditch flow

D A M

streamflow

streamflow

streamflow

stream channel (fig. A9). Martin and Pierce (1913, p. 257) 

also indicate that “Third ditch” diverted water to the north 

side of ‘Īao Stream, although the location of this ditch was 

not identified. 

Currently, the main diversions from ‘Īao Stream are 

the ‘Īao-Waikapū and ‘Īao-Māniania Ditches, which share a 

common intake near an altitude of 780 ft, and the Spreckels 

Ditch, with an intake near an altitude of 250 ft (fig. 7). A small 

private intake exists near an altitude of 650 ft and diverts water 

through a 6-in pipe for use on the south side of ‘Īao Stream.

A

B

ditch flow

ditch flow

streamflow

streamflow

Figure A7. Photographs of diversion intakes for private 

ÿauwai (ditches), South Waiehu Stream, Maui, Hawaiÿi. A, 

Intake on north side of stream near an altitude of 620 feet 

(July 17, 2006). B, Intake on south side of stream near an 

altitude of 570 feet (July 17, 2006). Arrows indicate general 

direction of flow.

The intake grate for the ‘Īao-Waikapū and ‘ĪaoMāniania Ditches is owned and maintained by WWC and is 

located immediately downstream of the crest of a dam with 

a downstream face that is veneered by concrete (fig. A10). 

The intake grate stretches about 33 ft across the entire lowflow channel of ‘Īao Stream and is about 4 ft long (in the 

direction of flow). The grate has 222 openings (about 0.07 

ft wide) between parallel steel bars and at the grate edges. 

Water that enters the intake grate drains into a collection 

sump and flows by gravity into the ditch system. The intake 

Appendix A 141
direction of

streamow

Figure A8. Photograph of Spreckels Ditch diversion intake 

on the south side of South Waiehu Stream near an altitude 

of 270 feet, Maui, Hawaiÿi (July 27, 2006).

in ‘Īao Stream has a design capacity of 60 Mgal/d, although 

a downstream control gate limits combined flow in the ‘ĪaoWaikapū and ‘Īao-Māniania Ditches to about 20 Mgal/d (18 

Mgal/d to the ‘Īao-Waikapū Ditch and 2 Mgal/d to the ‘ĪaoMāniania Ditch) (Suzuki, 2007).

The intake grate in ‘Īao Stream for the Spreckels Ditch 

is owned and maintained by HC&S and is located near the 

right (south) edge of a concrete-lined flood-control channel 

and immediately upstream of a chute in the channel (fig. 

A11). Upstream of the Spreckels Ditch intake, the low flow 

of ‘Īao Stream occurs near the right edge of the channel. The 

intake grate consists of three separate parts. The downstream 

intake grate is about 27 ft wide and 3 ft long (in the direction 

Figure A9. Photograph of concrete remnants related to the 

diversion intake for the Kama Ditch near an altitude of 430 

feet, ÿÏao Stream, Maui, Hawaiÿi (June 9, 2006).

A

B

Figure A10. Photographs of diversion intake common to 

the ÿÏao-Mäniania and ÿÏao-Waikapü Ditches near an altitude of 780 feet, ÿÏao Stream, Maui, Hawaiÿi. A, Intake grate 

(August 30, 2007). B, Diversion dam viewed from downstream (August, 30, 2007).

142 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
of flow) and has 206 openings that are about 0.1 ft wide 

between parallel steel bars and at the grate edges. The 

upstream intake grate nearest the right edge of the channel 

slopes upward in a downstream direction, is about 3 ft wide 

and 20 ft long (in the direction of flow), and has 17 openings 

that are about 0.1 ft wide between parallel steel bars and at 

the grate edges. The adjacent upstream intake grate itself has 

three parts: (1) an upstream sloping grate about 4 ft wide and 

12 ft long with 8 openings that are about 0.1 to 0.3 ft wide; 

(2) a downstream grate about 3 ft wide and 3 ft long with 

grid openings that are about 0.3 ft wide and 0.1 ft long; and 

(3) a vertical grate at the left edge of the upstream sloping 

part of the intake, with openings that are about 0.15 ft wide 

and up to 1.5 ft high at the downstream end. The capacity 

of the intake for Spreckels Ditch is unknown, although it 

likely exceeds 10 Mgal/d, judging from available discharge 

measurements and observations. 

Waikapu ̄ Stream

A map from 1894 of Waikapū Stream shows three 

unnamed ditches on the north side and one unnamed ditch 

on the south side of Waikapū Stream (Monsarrat, 1894). The 

uppermost ditch on the north side of Waikapū Stream appears 

to correspond to the Everett Ditch (also referred to as Palolo 

Ditch), which originates near an altitude of 900 ft. The 

remaining two unnamed ditches on the north side originate 

near altitudes of 710 and 560 ft, whereas the unnamed ditch 

on the south side originates near an altitude of 580 ft. 

Martin and Pierce (1913) indicate that water was 

diverted from Waikapū Stream through several ditches 

at various altitudes, and the South Side (Upper), Everett 

(Palolo), and Waihe‘e Ditches were shown (fig. A1). Martin 

and Pierce (1913, p. 257) also measured discharge in 

“Palama Ditch,” although the location of that ditch was not 

identified. Currently (2009), five known diversion intakes 

exist on Waikapū Stream: (1) the South Side Ditch (also 

referred to as South Waikapū Ditch) is the most upstream 

diversion, with an intake near an altitude of 1,120 ft (fig. 

A12); (2) the Everett Ditch intake is near an altitude of 900 

ft (fig. A13); (3) a private, community ‘auwai diverts water 

near an altitude of 560 ft (fig. A14); (4) the Waihe‘e Ditch 

intake is near an altitude of 440 ft (fig. A15); and (5) the 

Reservoir 6 intake is near an altitude of 410 ft (fig. A16). 

The intake for the South Side Ditch is owned and 

maintained by WWC and is located near the right (south) 

edge of Waikapū Stream on the upstream side of a 55-ft-long 

dam that stretches across the entire low-flow channel (fig. 

A12). The vertical intake for the South Side Ditch is 4.5 ft 

wide and 2.3 ft high and has a design capacity of about 5 

Mgal/d (Suzuki, 2007), although a control gate is set to limit 

flow in the South Side Ditch to about 3 Mgal/d (Suzuki, 

2007). 

The Everett Ditch intake was replaced in 1933, and that 

ditch was later abandoned when a landslide filled the intake 

and tunnel (Wilcox, 1996, p. 125). Sometime before June 

2006, the Everett Ditch intake was cleared, and water has 

since been flowing in the ditch for a distance of about 900 feet 

before returning to Waikapū Stream near an altitude of about 

850 feet. The intake for the Everett Ditch is located near the 

left (north) edge of the stream and consists of a steel intake 

grate that is about 2 ft wide and 4 ft long (in the direction of 

flow) (fig. A13). The intake has 10 openings that are about 

0.07 to 0.2 ft wide between parallel steel bars and at the grate 

edges, and water that enters the intake grate drains into a 

collection sump and flows by gravity into the ditch. Remnants 

A

B

Figure A11. Photographs of Spreckels Ditch diversion intake 

on the south side of ÿÏao Stream near an altitude of 250 feet, 

Maui, Hawaiÿi. A, Diversion intake just upstream of concrete 

chute (June 6, 2006). B, Closeup of parts of intake grate 

(June 6, 2006).

Appendix A 143
of an abandoned intake grate that stretched across the stream 

are adjacent to the existing intake. The capacity of the Everett 

Ditch intake is unknown but is less than the typical low flow 

of Waikapū Stream. During April 29 and April 30, 2008, 

discharges in the Everett Ditch near gaging station 16649000 

(fig. 7) were 0.36 and 0.14 Mgal/d (0.56 and 0.21 ft3/s), 

respectively. Measured discharges in Waikapū Stream, about 

600 ft upstream of the Everett Ditch intake, were 3.19 and 

1.29 Mgal/d (4.93 and 1.99 ft3/s), respectively, on April 29 and 

April 30, 2008. 

The intake for the Waihe‘e Ditch in Waikapū Stream is on 

the left (north) side of the stream (fig. A15). The main intake 

grate is about 10 ft wide and 2.5 ft long (in the direction of 

flow) with 51 openings that are about 0.08 ft wide between 

parallel steel bars and at the grate edges. A smaller intake 

grate (1.6 ft wide and 1.9 ft long with 17 openings that are 

0.05 ft wide) is located at the left edge of the main intake. The 

Waikapū Stream intake for Reservoir 6 is about 15 ft wide and 

3 ft long (in the direction of flow) with 53 openings that are 

about 0.2 ft wide and 35 openings (near the right edge of the 

channel) that are about 0.06 ft wide between parallel steel bars 

and at the grate edges (fig. A16). The capacities of the Waihe‘e 

Ditch and Reservoir 6 intakes each exceed 1 Mgal/d but are 

otherwise unknown.

A

B

toward intake

direction of ow

direction of ow

toward intake

tunnel

portal

Figure A12. Photographs of South Side Ditch diversion 

intake on the south side of Waikapü Stream near an altitude 

of 1,120 feet, Maui, Hawaiÿi. A, Diversion intake that leads 

into a tunnel (June 7, 2006). B, Diversion dam viewed from 

downstream (June 7, 2006).

A

B

intake

direction of

streamow

direction of streamow

Figure A13. Photographs of Everett Ditch diversion intake 

near an altitude of 900 feet, Waikapü Stream, Maui, Hawaiÿi 

(August 23, 2006). A, Diversion intake near the left side 

(viewed downstream) of the channel being cleared of 

debris. B, Intake grate cleared of debris.

144 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Figure A15. Photograph of diversion intake for Waiheÿe 

Ditch near an altitude of 440 feet, Waikapü Stream, Maui, 

Hawaiÿi (October 22, 2008).

Figure A16. Photograph of diversion intake for the Reservoir 6 Ditch 

near an altitude of 410 feet, Waikapu ̄ 

Stream, Maui, Hawaiÿi (March 17, 

2005).

direction of

ditch ow

direction of

streamow

Figure A14. Photograph of diversion intake for private 

ÿauwai (ditch) on the north side of Waikapü Stream near an 

altitude of 560 feet, Maui, Hawaiÿi (June 9, 2006).

Appendix A 145
Site ID Station name Date Time

Cubic feet per 

second

Million gallons 

per day

205610156324701 Waihee Riv at Waihee Ditch intake right, Maui, HI 06/16/2004 1221 0.36 0.23

205610156324702 Waihee Riv at Waihee Ditch intake left, Maui, HI 06/16/2004 1303 0.16 0.10

205613156323901 Unnamed Trib to Waihee Riv at Waihee Dt DS Maui, HI 06/16/2004 — 0.12 0.078

205613156323901 Unnamed Trib to Waihee Riv at Waihee Dt DS Maui, HI 10/12/2006 1415 0.18 0.12

205613156324401 Waihee River near alt 580 ft, Maui, HI 10/12/2006 1050 0.066 0.043

205613156324401 Waihee River near alt 580 ft, Maui, HI 12/11/2006 1328 1.18 0.763

205613156324401 Waihee River near alt 580 ft, Maui, HI 01/17/2007 1325 0.16 0.10

205613156324401 Waihee River near alt 580 ft, Maui, HI 02/08/2007 1600 0.1 0.06

205613156324401 Waihee River near alt 580 ft, Maui, HI 03/05/2007 1504 0.05 0.03

205613156324401 Waihee River near alt 580 ft, Maui, HI 04/03/2007 1442 0.03-0.04 0.02-0.03

205613156324401 Waihee River near alt 580 ft, Maui, HI 08/27/2007 1614 0.045 0.029

205613156324401 Waihee River near alt 580 ft, Maui, HI 10/16/2007 1725 0.051 0.033

205613156324401 Waihee River near alt 580 ft, Maui, HI 11/13/2007 1432 0.030 0.019

205613156324401 Waihee River near alt 580 ft, Maui, HI 12/17/2007 1559 0.59 0.38

205615156324301 RB inflow to Waihee River nr alt 560 ft, Maui, HI 10/12/2006 1324 1.70 1.10

205615156324301 RB inflow to Waihee River nr alt 560 ft, Maui, HI 12/11/2006 1223 0.18 0.12

205615156324301 RB inflow to Waihee River nr alt 560 ft, Maui, HI 01/17/2007 1223 0.63 0.41

205615156324201 Waihee River near altitude 560 feet, Maui, HI 04/03/2007 1349 0.91 0.59

205618156323901 Waihee River near altitude 530 ft, Maui, HI 02/27/2008 0932 40.7 26.3

205618156323901 Waihee River near altitude 530 ft, Maui, HI 02/28/2008 1007 40.4 26.1

205621156323601 RB inflow to Waihee River nr alt 510 ft, Maui, HI 10/12/2006 1442 0.022 0.014

205621156323601 RB inflow to Waihee River nr alt 510 ft, Maui, HI 12/11/2006 1435 0.082 0.053

205621156323601 RB inflow to Waihee River nr alt 510 ft, Maui, HI 01/17/2007 1503 0.057 0.037

205621156323601 RB inflow to Waihee River nr alt 510 ft, Maui, HI 02/26/2008 1526 0.026 0.017

205621156323601 RB inflow to Waihee River nr alt 510 ft, Maui, HI 02/28/2008 0952 0.018 0.012

205627156323401 Huluhulupueo Stream at Waihee River, Maui, HI 06/16/2004 1112 0.60 0.39

205627156323401 Huluhulupueo Stream at Waihee River, Maui, HI 10/12/2006 1541 0.12 0.078

205627156323401 Huluhulupueo Stream at Waihee River, Maui, HI 12/11/2006 1526 0.78 0.50

205627156323401 Huluhulupueo Stream at Waihee River, Maui, HI 01/17/2007 1409 0.55 0.36

205627156323401 Huluhulupueo Stream at Waihee River, Maui, HI 08/27/2007 1719 0.18 0.12

205627156323401 Huluhulupueo Stream at Waihee River, Maui, HI 02/26/2008 1450 0.13 0.084

205627156323401 Huluhulupueo Stream at Waihee River, Maui, HI 02/28/2008 0929 0.12 0.078

205627156323401 Huluhulupueo Stream at Waihee River, Maui, HI 05/30/2008 1116 0.051 0.033

205627156323401 Huluhulupueo Stream at Waihee River, Maui, HI 10/20/2008 1048 0.080 0.052

205627156323401 Huluhulupueo Stream at Waihee River, Maui, HI 11/18/2008 1509 0.47 0.30

205627156323401 Huluhulupueo Stream at Waihee River, Maui, HI 12/05/2008 0959 0.083 0.054

205627156323401 Huluhulupueo Stream at Waihee River, Maui, HI 12/19/2008 1238 0.11 0.071

205633156322401 Waihee River near altitude 445 ft, Maui, HI 02/28/2008 1600 41.2 26.6

205632156322001 Waihee River near alt 400 ft, Maui, HI 10/12/2006 0849 1.57 1.01

205632156322001 Waihee River near alt 400 ft, Maui, HI 12/11/2006 1639 2.94 1.90

205632156322001 Waihee River near alt 400 ft, Maui, HI 01/17/2007 1523 1.45 0.937

205632156322001 Waihee River near alt 400 ft, Maui, HI 07/09/2007 1557 2.26 1.46

205632156322001 Waihee River near alt 400 ft, Maui, HI 08/28/2007 0958 1.78 1.15

205632156322001 Waihee River near alt 400 ft, Maui, HI 09/18/2007 1328 19.3 12.5

205632156322001 Waihee River near alt 400 ft, Maui, HI 10/16/2007 1434 2.28 1.47

205632156322001 Waihee River near alt 400 ft, Maui, HI 11/13/2007 1633 1.98 1.28

205632156322001 Waihee River near alt 400 ft, Maui, HI 12/18/2007 1204 7.82 5.05

16615000 SPRECKELS DITCH NR WAIHEE, MAUI, HI 06/16/2004 1050 2.17 1.40

16615000 SPRECKELS DITCH NR WAIHEE, MAUI, HI 02/26/2008 1305 8.61 5.57

16615000 SPRECKELS DITCH NR WAIHEE, MAUI, HI 02/27/2008 1138 9.18 5.93

16615000 SPRECKELS DITCH NR WAIHEE, MAUI, HI 02/28/2008 0806 9.20 5.95

16615000 SPRECKELS DITCH NR WAIHEE, MAUI, HI 03/24/2008 1202 1.04 0.672

16615000 SPRECKELS DITCH NR WAIHEE, MAUI, HI 04/11/2008 1217 1.44 0.931

16615000 SPRECKELS DITCH NR WAIHEE, MAUI, HI 05/01/2008 1004 1.32 0.853

16615000 SPRECKELS DITCH NR WAIHEE, MAUI, HI 05/30/2008 0929 1.14 0.737

16615000 SPRECKELS DITCH NR WAIHEE, MAUI, HI 07/02/2008 0831 1.59 1.03

16615000 SPRECKELS DITCH NR WAIHEE, MAUI, HI 07/30/2008 1118 1.20 0.776

16615000 SPRECKELS DITCH NR WAIHEE, MAUI, HI 09/24/2008 0859 1.81 1.17

16615000 SPRECKELS DITCH NR WAIHEE, MAUI, HI 10/20/2008 0947 1.92 1.24

205634156321801 Waihee River near alt 390 ft, Maui, HI 08/28/2007 1531 0.014 0.0090

205634156321801 Waihee River near alt 390 ft, Maui, HI 10/16/2007 1319 0.005 0.003

Discharge

Waiheÿe River

Table 12. U.S. Geological Survey miscellaneous discharge measurements during 2004–2009, sorted by Nä Wai ÿEhä 

stream and from upstream to downstream, Maui, Hawaiÿi.

[Dt, ditch; Str, stream; Trib, tributary; alt, altitude; ft, feet; nr, near; DS, downstream; US, upstream; LB, left bank (viewed downstream); RB, right bank (viewed 

downstream); <, less than; ~, about; —, no data]

Appendix B. Miscellaneous Discharge Measurements During 2004–2009, 

Na ̄ Wai ÿEha ̄,Maui, Hawaiÿi

146 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Site ID Station name Date Time

Cubic feet per 

second

Million gallons 

per day

Discharge

205634156321801 Waihee River near alt 390 ft, Maui, HI 11/13/2007 1538 0.001 0.001

205634156321801 Waihee River near alt 390 ft, Maui, HI 12/18/2007 0912 1.33 0.860

205634156321801 Waihee River near alt 390 ft, Maui, HI 02/26/2008 1126 31.4 20.3

205634156321801 Waihee River near alt 390 ft, Maui, HI 02/27/2008 1302 31.0 20.0

205634156321801 Waihee River near alt 390 ft, Maui, HI 02/28/2008 1256 30.4 19.6

205634156321801 Waihee River near alt 390 ft, Maui, HI 02/29/2008 1154 31.0 20.0

205634156321801 Waihee River near alt 390 ft, Maui, HI 04/11/2008 1100 <0.01 <0.006

205634156321801 Waihee River near alt 390 ft, Maui, HI 05/01/2008 1200 <0.001 <0.0006

205634156321801 Waihee River near alt 390 ft, Maui, HI 05/30/2008 1140 <0.001 <0.0006

205634156321801 Waihee River near alt 390 ft, Maui, HI 06/30/2008 1818 <0.001 <0.0006

205634156321801 Waihee River near alt 390 ft, Maui, HI 07/02/2008 0845 <0.001 <0.0006

205634156321801 Waihee River near alt 390 ft, Maui, HI 07/30/2008 1145 <0.001 <0.0006

205634156321801 Waihee River near alt 390 ft, Maui, HI 09/23/2008 1020 ~0.001 ~0.0006

205634156321801 Waihee River near alt 390 ft, Maui, HI 10/20/2008 1217 0.001 0.001

205633156321901 Spreckels Ditch overflow to Waihee River, Maui, HI 06/16/2004 1139 0.10 0.065

205633156321901 Spreckels Ditch overflow to Waihee River, Maui, HI 02/26/2008 — 0.1 0.06

205633156321901 Spreckels Ditch overflow to Waihee River, Maui, HI 02/27/2008 0900 0.1 0.06

205633156321901 Spreckels Ditch overflow to Waihee River, Maui, HI 02/28/2008 0800 0.1 0.06

205633156321901 Spreckels Ditch overflow to Waihee River, Maui, HI 02/29/2008 1345 0.1 0.06

205634156321101 Waihee River near altitude 360 ft, Maui, HI 02/29/2008 1243 32.5 21.0

205634156321101 Waihee River near altitude 360 ft, Maui, HI 12/01/2008 1146 8.49 5.49

205634156321101 Waihee River near altitude 360 ft, Maui, HI 12/02/2008 0840 8.61 5.57

205634156320601 Waihee River near altitude 320 ft, Maui, HI 12/01/2008 1437 7.79 5.04

205634156320601 Waihee River near altitude 320 ft, Maui, HI 12/02/2008 0930 7.89 5.10

205633156315801 Waihee River near altitude 310 ft, Maui, HI 02/29/2008 0937 32.2 20.8

205633156315801 Waihee River near altitude 310 ft, Maui, HI 11/19/2008 1624 10.8 6.98

205633156315801 Waihee River near altitude 310 ft, Maui, HI 11/20/2008 1020 9.20 5.95

205633156315801 Waihee River near altitude 310 ft, Maui, HI 11/21/2008 0958 9.89 6.39

205633156315801 Waihee River near altitude 310 ft, Maui, HI 12/02/2008 1036 9.72 6.28

205634156315001 Waihee River near altitude 290 ft, Maui, HI 02/29/2008 0929 32.0 20.7

205634156315001 Waihee River near altitude 290 ft, Maui, HI 11/20/2008 1206 8.74 5.65

205634156314701 Waihee River near altitude 285 ft, Maui, HI 02/26/2008 0935 35.0 22.6

205634156314701 Waihee River near altitude 285 ft, Maui, HI 02/26/2008 1620 33.9 21.9

205634156314701 Waihee River near altitude 285 ft, Maui, HI 02/27/2008 1431 34.1 22.0

205634156314701 Waihee River near altitude 285 ft, Maui, HI 02/28/2008 0903 35.0 22.6

205634156314701 Waihee River near altitude 285 ft, Maui, HI 02/29/2008 0932 33.6 21.7

205634156314201 Waihee River upstream of Field 1 intake, Maui, HI 06/16/2004 1304 0.01 0.01

205634156314201 Waihee River upstream of Field 1 intake, Maui, HI 11/19/2008 1450 11.5 7.43

205634156314201 Waihee River upstream of Field 1 intake, Maui, HI 11/20/2008 0900 8.69 5.62

205634156314201 Waihee River upstream of Field 1 intake, Maui, HI 11/21/2008 0848 9.19 5.94

205634156314201 Waihee River upstream of Field 1 intake, Maui, HI 12/02/2008 1201 9.29 6.00

205634156313801 Waihee Riv downstream of Field 1 intake, Maui, HI 06/16/2004 1328 0.036 0.023

205639156305801 Waihee River near altitude 100 ft, Maui, HI 02/27/2008 1609 35.0 22.6

205639156305801 Waihee River near altitude 100 ft, Maui, HI 02/28/2008 1105 34.7 22.4

205639156305801 Waihee River near altitude 100 ft, Maui, HI 11/20/2008 1540 11.8 7.63

205639156305801 Waihee River near altitude 100 ft, Maui, HI 11/21/2008 1124 9.57 6.19

205639156305801 Waihee River near altitude 100 ft, Maui, HI 12/02/2008 1357 13.1 8.47

205639156305801 Waihee River near altitude 100 ft, Maui, HI 12/04/2008 1646 11.6 7.50

205639156305401 RB inflow to Waihee River nr alt 80 ft, Maui, HI 02/28/2008 1438 0.11 0.071

205639156305401 RB inflow to Waihee River nr alt 80 ft, Maui, HI 11/21/2008 1200 0 0

205639156305401 RB inflow to Waihee River nr alt 80 ft, Maui, HI 12/02/2008 1454 0.045 0.029

205639156305401 RB inflow to Waihee River nr alt 80 ft, Maui, HI 12/04/2008 1600 0.05 0.03

205640156305201 Waihee River near alt 75 ft, Maui, HI 12/12/2006 1140 2.49 1.61

205644156304401 Waihee River near alt 45 ft, Maui, HI 12/12/2006 0937 2.23 1.44

205644156304401 Waihee River near alt 45 ft, Maui, HI 01/17/2007 0930 1.97 1.27

205644156304401 Waihee River near alt 45 ft, Maui, HI 02/05/2007 1506 2.05 1.33

205644156304401 Waihee River near alt 45 ft, Maui, HI 02/07/2007 1456 2.00 1.29

205644156304401 Waihee River near alt 45 ft, Maui, HI 03/05/2007 1051 2.34 1.51

205644156304401 Waihee River near alt 45 ft, Maui, HI 04/30/2007 1019 3.61 2.33

205644156304401 Waihee River near alt 45 ft, Maui, HI 08/27/2007 1254 1.92 1.24

205644156304401 Waihee River near alt 45 ft, Maui, HI 10/16/2007 1019 2.72 1.76

205644156304401 Waihee River near alt 45 ft, Maui, HI 11/13/2007 1057 2.66 1.72

Table 12. U.S. Geological Survey miscellaneous discharge measurements during 2004–2009, sorted by Nä Wai ÿEhä 

stream and from upstream to downstream, Maui, Hawaiÿi—Continued.

Appendix B 147
Table 12. U.S. Geological Survey miscellaneous discharge measurements during 2004–2009, sorted by Na ̄ Wai ÿEh ̄a 

stream and from upstream to downstream, Maui, Hawaiÿi—Continued.

Site ID Station name Date Time

Cubic feet per 

second

Million gallons 

per day

Discharge

205644156304401 Waihee River near alt 45 ft, Maui, HI 12/17/2007 1100 3.78 2.44

205644156304401 Waihee River near alt 45 ft, Maui, HI 02/26/2008 1645 34.4 22.2

205644156304401 Waihee River near alt 45 ft, Maui, HI 02/27/2008 1724 33.9 21.9

205644156304401 Waihee River near alt 45 ft, Maui, HI 02/28/2008 1306 34.8 22.5

205644156304401 Waihee River near alt 45 ft, Maui, HI 04/11/2008 0918 2.86 1.85

205644156304401 Waihee River near alt 45 ft, Maui, HI 04/30/2008 1658 2.36 1.53

205644156304401 Waihee River near alt 45 ft, Maui, HI 07/02/2008 1205 3.30 2.13

205644156304401 Waihee River near alt 45 ft, Maui, HI 07/30/2008 1322 3.06 1.98

205644156304401 Waihee River near alt 45 ft, Maui, HI 08/26/2008 1110 2.13 1.38

205644156304401 Waihee River near alt 45 ft, Maui, HI 09/23/2008 1128 2.56 1.65

205644156304401 Waihee River near alt 45 ft, Maui, HI 10/20/2008 1340 2.15 1.39

205644156304401 Waihee River near alt 45 ft, Maui, HI 11/20/2008 1357 8.48 5.48

205644156304401 Waihee River near alt 45 ft, Maui, HI 11/21/2008 1230 9.13 5.90

205644156304401 Waihee River near alt 45 ft, Maui, HI 12/02/2008 1544 12.8 8.27

205644156304401 Waihee River near alt 45 ft, Maui, HI 12/04/2008 1523 11.7 7.56

205648156304301 Waihee River near alt 35 ft, Maui, HI 08/24/2006 1216 1.79 1.16

205648156304301 Waihee River near alt 35 ft, Maui, HI 10/13/2006 1004 2.20 1.42

205651156303901 Waihee River near mouth, Maui, HI 06/16/2004 1507 1.41 0.911

205434156315701 North Waiehu Stream near alt 920 ft, Maui, HI 10/10/2006 1350 3.52 2.28

205434156315701 North Waiehu Stream near alt 920 ft, Maui, HI 03/07/2007 1000 3.42 2.21

205434156315701 North Waiehu Stream near alt 920 ft, Maui, HI 07/11/2007 1258 4.63 2.99

205434156315701 North Waiehu Stream near alt 920 ft, Maui, HI 09/19/2007 1458 3.23 2.09

205434156315701 North Waiehu Stream near alt 920 ft, Maui, HI 10/19/2007 0927 2.89 1.87

205434156315701 North Waiehu Stream near alt 920 ft, Maui, HI 11/14/2007 0937 2.62 1.69

205434156315701 North Waiehu Stream near alt 920 ft, Maui, HI 12/19/2007 0930 3.14 2.03

205434156315701 North Waiehu Stream near alt 920 ft, Maui, HI 03/10/2008 1100 3.62 2.34

205434156315701 North Waiehu Stream near alt 920 ft, Maui, HI 03/11/2008 0948 3.40 2.20

205434156315701 North Waiehu Stream near alt 920 ft, Maui, HI 03/11/2008 1123 3.37 2.18

205434156315701 North Waiehu Stream near alt 920 ft, Maui, HI 03/12/2008 0906 3.65 2.36

205434156315701 North Waiehu Stream near alt 920 ft, Maui, HI 03/13/2008 0911 3.62 2.34

205434156315701 North Waiehu Stream near alt 920 ft, Maui, HI 05/29/2008 0943 3.25 2.10

205434156315701 North Waiehu Stream near alt 920 ft, Maui, HI 07/01/2008 1035 3.22 2.08

205434156315701 North Waiehu Stream near alt 920 ft, Maui, HI 07/28/2008 1122 3.55 2.29

205434156315701 North Waiehu Stream near alt 920 ft, Maui, HI 08/25/2008 1021 2.92 1.89

205434156315701 North Waiehu Stream near alt 920 ft, Maui, HI 10/21/2008 1005 2.74 1.77

205434156315701 North Waiehu Stream near alt 920 ft, Maui, HI 11/19/2008 0929 4.19 2.71

205434156315501 North Waiehu Stream near alt 900 ft, Maui, HI 07/25/2006 1453 4.10 2.65

205435156315201 N Waiehu Str US of N Waiehu Ditch intake, Maui, HI 08/17/2005 1054 3.29 2.13

205435156315001 N. Waiehu Ditch intake, N. Waiehu Stream, Maui, HI 08/17/2005 1148 3.00 1.94

205437156312301 North Waiehu ditch near alt 840 ft, Maui, HI 07/25/2006 1707 3.76 2.43

205437156312301 North Waiehu ditch near alt 840 ft, Maui, HI 10/10/2006 1124 3.11 2.01

205435156314701 North Waiehu Stream near alt 820 ft, Maui, HI 10/10/2006 1631 0.61 0.39

205435156314701 North Waiehu Stream near alt 820 ft, Maui, HI 07/11/2007 1011 0.37 0.24

205435156314701 North Waiehu Stream near alt 820 ft, Maui, HI 09/19/2007 1725 0.33 0.21

205435156314701 North Waiehu Stream near alt 820 ft, Maui, HI 10/19/2007 1136 0.48 0.31

205435156314701 North Waiehu Stream near alt 820 ft, Maui, HI 11/14/2007 1115 0.32 0.21

205435156314701 North Waiehu Stream near alt 820 ft, Maui, HI 11/14/2007 1136 0.37 0.24

205435156314701 North Waiehu Stream near alt 820 ft, Maui, HI 12/19/2007 1110 0.81 0.52

205435156314701 North Waiehu Stream near alt 820 ft, Maui, HI 05/29/2008 1148 0.60 0.39

205435156314701 North Waiehu Stream near alt 820 ft, Maui, HI 07/01/2008 1244 1.55 1.00

205435156314701 North Waiehu Stream near alt 820 ft, Maui, HI 07/28/2008 1237 0.71 0.46

205435156314701 North Waiehu Stream near alt 820 ft, Maui, HI 08/25/2008 1549 0.50 0.32

205435156314701 North Waiehu Stream near alt 820 ft, Maui, HI 10/21/2008 1120 0.38 0.25

205435156314701 North Waiehu Stream near alt 820 ft, Maui, HI 11/19/2008 1103 1.57 1.01

205432156312801 N Waiehu Stream near altitude 625 ft, Maui, HI 03/06/2007 1724 2.60 1.68

205432156312801 N Waiehu Stream near altitude 625 ft, Maui, HI 03/07/2007 1142 2.43 1.57

205432156312701 N Waiehu Str US of Waihee Ditch flume, Maui, HI 08/17/2005 0930 0 0

205432156312701 N Waiehu Str US of Waihee Ditch flume, Maui, HI 10/10/2006 1730 0 0

205432156310401 N Waiehu Stream near altitude 475 feet, Maui, HI 03/06/2007 0835 2.03 1.31

205432156310401 N Waiehu Stream near altitude 475 feet, Maui, HI 03/07/2007 1309 2.01 1.30

205432156310401 N Waiehu Stream near altitude 475 feet, Maui, HI 03/10/2008 1438 1.80 1.16

North Waiehu Stream

148 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Table 12. U.S. Geological Survey miscellaneous discharge measurements during 2004–2009, sorted by Na ̄ Wai ÿEh ̄a 

stream and from upstream to downstream, Maui, Hawaiÿi—Continued.

Site ID Station name Date Time

Cubic feet per 

second

Million gallons 

per day

Discharge

205432156310401 N Waiehu Stream near altitude 475 feet, Maui, HI 03/11/2008 1334 1.76 1.14

205432156310401 N Waiehu Stream near altitude 475 feet, Maui, HI 03/12/2008 1109 1.76 1.14

205432156310401 N Waiehu Stream near altitude 475 feet, Maui, HI 03/13/2008 1110 1.81 1.17

205432156310401 N Waiehu Stream near altitude 475 feet, Maui, HI 03/14/2008 0842 1.78 1.15

205433156310101 N Waiehu Stream at Malaihi Road, Maui, HI 08/17/2005 1200 0 0

205435156305801 N Waiehu Stream near altitude 450 feet, Maui, HI 10/10/2006 1800 0 0

205435156305801 N Waiehu Stream near altitude 450 feet, Maui, HI 12/19/2007 — 0 0

205450156303601 N Waiehu Stream near altitude 280 feet, Maui, HI 03/06/2007 1158 1.48 0.957

205450156303601 N Waiehu Stream near altitude 280 feet, Maui, HI 03/07/2007 1418 1.46 0.944

205450156303601 N Waiehu Stream near altitude 280 feet, Maui, HI 03/10/2008 1625 0.89 0.58

205450156303601 N Waiehu Stream near altitude 280 feet, Maui, HI 03/11/2008 1440 1.10 0.711

205450156303601 N Waiehu Stream near altitude 280 feet, Maui, HI 03/12/2008 1219 1.08 0.698

205450156303601 N Waiehu Stream near altitude 280 feet, Maui, HI 03/13/2008 1112 1.15 0.743

205450156303601 N Waiehu Stream near altitude 280 feet, Maui, HI 03/14/2008 0839 1.27 0.821

205451156303401 North Waiehu Stream near alt 260 ft, Maui, HI 07/27/2006 1810 0.10 0.065

205452156303401 RB inflow to N. Waiehu Str nr alt 260 ft, Maui, HI 03/07/2007 1450 0.2 0.1

205450156303201 N Waiehu Stream near altitude 240 feet, Maui, HI 03/06/2007 1011 1.45 0.937

205449156302801 N Waiehu Stream upstream of fork, Maui, HI 08/17/2005 1502 0.28 0.18

205449156302801 N Waiehu Stream upstream of fork, Maui, HI 07/27/2006 1741 0.14 0.090

16610000 SOUTH WAIEHU STREAM NR WAILUKU, MAUI, HI 11/17/2008 1243 2.10 1.36

205426156313601 South Waiehu Stream near alt 670 ft, Maui, HI 08/29/2007 1304 2.33 1.51

205426156313601 South Waiehu Stream near alt 670 ft, Maui, HI 11/16/2007 1017 2.06 1.33

205426156313601 South Waiehu Stream near alt 670 ft, Maui, HI 12/20/2007 1515 2.35 1.52

205426156313601 South Waiehu Stream near alt 670 ft, Maui, HI 03/13/2008 1448 2.47 1.60

205426156313601 South Waiehu Stream near alt 670 ft, Maui, HI 05/29/2008 1421 2.40 1.55

205426156313601 South Waiehu Stream near alt 670 ft, Maui, HI 07/30/2008 1500 2.44 1.58

205426156313601 South Waiehu Stream near alt 670 ft, Maui, HI 08/29/2008 0852 2.27 1.47

205426156313601 South Waiehu Stream near alt 670 ft, Maui, HI 09/23/2008 1354 2.46 1.59

205426156313601 South Waiehu Stream near alt 670 ft, Maui, HI 10/21/2008 1404 2.22 1.43

205426156313601 South Waiehu Stream near alt 670 ft, Maui, HI 11/17/2008 1024 2.05 1.33

205427156313101 South Waiehu Stream near alt 635 ft, Maui, HI 07/26/2006 1050 3.70 2.39

205427156313101 South Waiehu Stream near alt 635 ft, Maui, HI 01/18/2007 1615 3.42 2.21

205427156313101 South Waiehu Stream near alt 635 ft, Maui, HI 05/04/2007 1048 2.69 1.74

205421156310301 Kuleana Ditch nr alt 600ft,LB S Waiehu Str, Maui, HI 07/26/2006 1734 0.43 0.28

205423156311501 Ditch return to S Waiehu Str nr alt 550 ft, Maui, HI 07/26/2006 — <0.005 <0.003

205420156311301 S Waiehu Str DS of Waihee Ditch flume, Maui, HI 08/17/2005 1124 3.20 2.07

205420156311301 S Waiehu Str DS of Waihee Ditch flume, Maui, HI 08/29/2007 1619 1.68 1.09

205420156311302 Kuleana Ditch nr 540 ft, RB S Waiehu Str, Maui, HI 07/26/2006 1311 0.26 0.17

205420156311302 Kuleana Ditch nr 540 ft, RB S Waiehu Str, Maui, HI 08/29/2007 1655 0.57 0.37

205415156310001 South Waiehu Stream near alt 460 ft, Maui, HI 07/26/2006 1615 2.33 1.51

205422156305401 South Waiehu Stream near alt 405 ft, Maui, HI 07/26/2006 1434 2.24 1.45

205422156305401 South Waiehu Stream near alt 405 ft, Maui, HI 07/27/2006 0949 2.78 1.80

205439156303401 S Waiehu Str US of Spreckels Dt intake, Maui, HI 08/17/2005 1500 3.67 2.37

205439156303401 S Waiehu Str US of Spreckels Dt intake, Maui, HI 07/27/2006 1228 2.24 1.45

205439156303401 S Waiehu Str US of Spreckels Dt intake, Maui, HI 07/12/2007 1303 1.99 1.29

205439156303401 S Waiehu Str US of Spreckels Dt intake, Maui, HI 08/03/2007 0900 2.00 1.29

205439156303401 S Waiehu Str US of Spreckels Dt intake, Maui, HI 08/03/2007 1140 1.74 1.12

205439156303401 S Waiehu Str US of Spreckels Dt intake, Maui, HI 11/14/2007 1419 1.56 1.01

205448156302801 S Waiehu Stream upstream of fork, Maui, HI 08/17/2005 1627 0.020 0.013

205448156302801 S Waiehu Stream upstream of fork, Maui, HI 03/06/2007 1230 0.5 0.3

205448156302801 S Waiehu Stream upstream of fork, Maui, HI 03/07/2007 1500 0.5 0.3

205451156302401 Waiehu Stream near alt 210 ft, Maui, HI 07/27/2006 1709 0.21 0.14

205455156302301 Waiehu Stream near alt 190 ft, Maui, HI 03/06/2007 1402 1.91 1.23

205455156302301 Waiehu Stream near alt 190 ft, Maui, HI 03/07/2007 1515 2.24 1.45

205455156302301 Waiehu Stream near alt 190 ft, Maui, HI 03/08/2007 1456 1.75 1.13

205455156302301 Waiehu Stream near alt 190 ft, Maui, HI 04/02/2007 1120 0.48 0.31

205455156302301 Waiehu Stream near alt 190 ft, Maui, HI 09/21/2007 1408 0.40 0.26

205455156302301 Waiehu Stream near alt 190 ft, Maui, HI 11/14/2007 1622 0.21 0.14

205455156302301 Waiehu Stream near alt 190 ft, Maui, HI 12/19/2007 1415 0.89 0.58

Waiehu Stream

South Waiehu Stream

Appendix B 149
Table 12. U.S. Geological Survey miscellaneous discharge measurements during 2004–2009, sorted by Na ̄ Wai ÿEh ̄a 

stream and from upstream to downstream, Maui, Hawaiÿi—Continued.

Site ID Station name Date Time

Cubic feet per 

second

Million gallons 

per day

Discharge

205455156302301 Waiehu Stream near alt 190 ft, Maui, HI 03/11/2008 1509 1.32 0.853

205455156302301 Waiehu Stream near alt 190 ft, Maui, HI 03/12/2008 1403 1.53 0.989

205455156302301 Waiehu Stream near alt 190 ft, Maui, HI 03/13/2008 1218 1.40 0.905

205455156302301 Waiehu Stream near alt 190 ft, Maui, HI 03/14/2008 0940 1.44 0.931

205455156302301 Waiehu Stream near alt 190 ft, Maui, HI 05/01/2008 1314 0.36 0.23

205455156302301 Waiehu Stream near alt 190 ft, Maui, HI 07/02/2008 1336 0.29 0.19

205455156302301 Waiehu Stream near alt 190 ft, Maui, HI 08/29/2008 1004 0.39 0.25

205455156302301 Waiehu Stream near alt 190 ft, Maui, HI 09/24/2008 1318 0.37 0.24

205455156302301 Waiehu Stream near alt 190 ft, Maui, HI 10/21/2008 1547 0.45 0.29

205455156302301 Waiehu Stream near alt 190 ft, Maui, HI 12/03/2008 1700 0.42 0.27

205504156295101 Waiehu Stream at Kahekili Highway, Maui, HI 08/17/2005 1657 0.46 0.30

205506156294501 Waiehu Stream near altitude 50 feet, Maui, HI 03/06/2007 1533 1.31 0.847

205506156294501 Waiehu Stream near altitude 50 feet, Maui, HI 03/07/2007 1612 1.59 1.03

205506156293501 Waiehu Stream near mouth, Maui, HI 08/17/2005 1619 0.19 0.12

205506156293501 Waiehu Stream near mouth, Maui, HI 03/12/2008 1557 0.95 0.61

205506156293501 Waiehu Stream near mouth, Maui, HI 03/13/2008 1213 0.89 0.58

205506156293501 Waiehu Stream near mouth, Maui, HI 03/14/2008 0942 1.27 0.821

205254156322301 Right branch of Iao Str nr alt 800 ft, Maui, HI 08/28/2008 1303 3.83 2.48

205257156322001 Iao Stream DS of Maniania Ditch, Maui, HI 09/21/2004 0855 0.08 0.05

205257156321901 Iao Stream near alt 755 ft, Maui, HI 07/24/2006 1347 0.008 0.01

205256156321801 Iao Stream near alt 750 ft, Maui, HI 10/11/2006 1235 0.047 0.030

205256156321801 Iao Stream near alt 750 ft, Maui, HI 08/30/2007 1120 0.094 0.061

205256156321801 Iao Stream near alt 750 ft, Maui, HI 09/21/2007 1032 0.062 0.040

205256156321701 Iao Stream near alt 745 ft, Maui, HI 01/16/2007 1540 0.30 0.19

205256156321601 Iao Stream near alt 740 ft, Maui, HI 08/30/2007 1042 0.24 0.16

205256156321601 Iao Stream near alt 740 ft, Maui, HI 09/21/2007 1050 0.23 0.15

205256156321601 Iao Stream near alt 740 ft, Maui, HI 11/15/2007 1736 0.23 0.15

205256156321301 RB return flow to Iao Str nr alt 732 ft, Maui, HI 01/16/2007 1751 0.04 0.03

205256156321302 RB return flow to Iao Str nr alt 730 ft, Maui, HI 10/11/2006 1126 0.011 0.0071

205256156321302 RB return flow to Iao Str nr alt 730 ft, Maui, HI 01/16/2007 1745 0.040 0.026

205256156321303 Iao Stream near alt 725 ft, Maui, HI 07/24/2006 1110 0.49 0.32

205256156321303 Iao Stream near alt 725 ft, Maui, HI 10/11/2006 1138 0.40 0.26

205256156321303 Iao Stream near alt 725 ft, Maui, HI 01/16/2007 1647 0.87 0.56

205257156321001 Iao Stream at Kepaniwai Park, Maui, HI 09/21/2004 1005 0.48 0.31

205300156321401 Maniania Ditch Leakage to Iao Stream, Maui, HI 09/21/2004 0930 0.010 0.0065

205257156321101 LB return flow to Iao Str near alt 715 ft, Maui, HI 07/24/2006 1049 0.026 0.017

205257156321101 LB return flow to Iao Str near alt 715 ft, Maui, HI 10/11/2006 1031 0.018 0.012

205257156321002 Trib to Iao Stream at Kepaniwai Park, Maui, HI 09/21/2004 0945 0.17 0.11

205257156321002 Trib to Iao Stream at Kepaniwai Park, Maui, HI 07/24/2006 1200 0.087 0.056

205257156321002 Trib to Iao Stream at Kepaniwai Park, Maui, HI 10/11/2006 1321 0.094 0.061

205257156321002 Trib to Iao Stream at Kepaniwai Park, Maui, HI 08/30/2007 1205 0.062 0.040

205257156321002 Trib to Iao Stream at Kepaniwai Park, Maui, HI 11/16/2007 1309 0.051 0.033

205257156321002 Trib to Iao Stream at Kepaniwai Park, Maui, HI 05/30/2008 1409 0.051 0.033

205257156321002 Trib to Iao Stream at Kepaniwai Park, Maui, HI 09/24/2008 1510 0.045 0.029

205257156321002 Trib to Iao Stream at Kepaniwai Park, Maui, HI 10/23/2008 0839 0.057 0.037

205257156321002 Trib to Iao Stream at Kepaniwai Park, Maui, HI 11/21/2008 1335 0.051 0.033

205257156321002 Trib to Iao Stream at Kepaniwai Park, Maui, HI 12/03/2008 1352 0.051 0.033

205258156320201 LB return flow to Iao Stream nr alt 670 ft, Maui, HI 07/24/2006 1215 0.11 0.071

205258156320201 LB return flow to Iao Stream nr alt 670 ft, Maui, HI 10/11/2006 1345 0.12 0.078

205300156320001 Iao Stream near alt 660 ft, Maui, HI 07/24/2006 1515 0.37 0.24

205300156320002 Iao Stream near alt 655 ft, Maui, HI 07/24/2006 1530 0.19 0.12

205300156320002 Iao Stream near alt 655 ft, Maui, HI 10/11/2006 1543 0.10 0.065

205301156315901 Iao Stream near alt 650 ft, Maui, HI 07/24/2006 1600 0.087 0.056

205301156315901 Iao Stream near alt 650 ft, Maui, HI 10/11/2006 1500 0 0

205303156315201 Duey diversion from Iao Stream, Maui, HI 09/21/2004 1125 0.14 0.090

205303156315201 Duey diversion from Iao Stream, Maui, HI 07/24/2006 1620 0.083 0.054

205303156315101 Iao Stream downstream of Duey diversion, Maui, HI 09/21/2004 1156 0.29 0.19

205303156314701 Iao Stream near alt 595 ft, Maui, HI 12/14/2006 1220 22.8 14.7

205303156314701 Iao Stream near alt 595 ft, Maui, HI 07/13/2007 0812 2.90 1.87

205303156314701 Iao Stream near alt 595 ft, Maui, HI 09/18/2007 1730 38.7 25.0

205303156314701 Iao Stream near alt 595 ft, Maui, HI 09/19/2007 1009 34.4 22.2

ÿÏao Stream

150 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Table 12. U.S. Geological Survey miscellaneous discharge measurements during 2004–2009, sorted by Na ̄ Wai ÿEh ̄a 

stream and from upstream to downstream, Maui, Hawaiÿi—Continued.

Site ID Station name Date Time

Cubic feet per 

second

Million gallons 

per day

Discharge

205303156314701 Iao Stream near alt 595 ft, Maui, HI 09/19/2007 1150 28.2 18.2

205303156314701 Iao Stream near alt 595 ft, Maui, HI 11/15/2007 1632 0.25 0.16

205303156314701 Iao Stream near alt 595 ft, Maui, HI 12/18/2007 1653 16.8 10.9

205303156314701 Iao Stream near alt 595 ft, Maui, HI 01/14/2008 1212 29.6 19.1

205303156314701 Iao Stream near alt 595 ft, Maui, HI 01/15/2008 1635 35.7 23.1

205303156314701 Iao Stream near alt 595 ft, Maui, HI 01/16/2008 1055 31.2 20.2

205303156314701 Iao Stream near alt 595 ft, Maui, HI 01/17/2008 0933 28.3 18.3

205303156314701 Iao Stream near alt 595 ft, Maui, HI 01/18/2008 0927 27.0 17.5

205303156314701 Iao Stream near alt 595 ft, Maui, HI 02/11/2008 1253 45.0 29.1

205303156314701 Iao Stream near alt 595 ft, Maui, HI 02/12/2008 0839 40.4 26.1

205303156314701 Iao Stream near alt 595 ft, Maui, HI 02/13/2008 1313 35.6 23.0

205303156314701 Iao Stream near alt 595 ft, Maui, HI 02/14/2008 1225 34.4 22.2

205303156314701 Iao Stream near alt 595 ft, Maui, HI 02/15/2008 0901 31.8 20.6

205303156314701 Iao Stream near alt 595 ft, Maui, HI 02/15/2008 1125 31.7 20.5

205303156314701 Iao Stream near alt 595 ft, Maui, HI 03/12/2008 1718 0.5 0.3

205303156314701 Iao Stream near alt 595 ft, Maui, HI 04/10/2008 1110 23.0 14.9

205303156314701 Iao Stream near alt 595 ft, Maui, HI 05/30/2008 1329 0.24 0.16

205303156314701 Iao Stream near alt 595 ft, Maui, HI 07/02/2008 1511 0.28 0.18

205303156314701 Iao Stream near alt 595 ft, Maui, HI 08/27/2008 1408 0.99 0.64

205303156314701 Iao Stream near alt 595 ft, Maui, HI 10/20/2008 1548 0.35 0.23

205303156314701 Iao Stream near alt 595 ft, Maui, HI 12/03/2008 1447 0.40 0.26

205303156314001 Duey return at Iao Stream, Maui, HI 09/21/2004 1355 0.030 0.019

205303156314001 Duey return at Iao Stream, Maui, HI 09/22/2004 1300 0.070 0.045

205303156314001 Duey return at Iao Stream, Maui, HI 12/14/2006 1018 0.01 0.01

205303156314001 Duey return at Iao Stream, Maui, HI 01/14/2008 1340 0.05-0.1 0.03-0.06

205303156314001 Duey return at Iao Stream, Maui, HI 01/16/2008 1205 0.4-0.5 0.3

205303156314001 Duey return at Iao Stream, Maui, HI 01/17/2008 1050 0.4-0.5 0.3

205303156314001 Duey return at Iao Stream, Maui, HI 01/18/2008 1100 0.4-0.5 0.3

205303156314001 Duey return at Iao Stream, Maui, HI 02/11/2008 1435 0.005 0.003

205303156314001 Duey return at Iao Stream, Maui, HI 02/12/2008 1630 0.001 0.001

205303156314001 Duey return at Iao Stream, Maui, HI 02/13/2008 1445 0.3 0.2

205303156314001 Duey return at Iao Stream, Maui, HI 02/14/2008 1415 0.3 0.2

205303156314001 Duey return at Iao Stream, Maui, HI 02/15/2008 1055 0.3 0.2

205303156314002 Iao Stream downstream of Duey return, Maui, HI 09/21/2004 1450 0.32 0.21

205301156310501 Iao Stream at Kama Ditch intake, Maui, HI 09/21/2004 1530 0 0

205300156305501 RB swale, Iao Str near altitude 400 feet, Maui, HI 01/16/2008 1225 0.1-0.2 0.06-0.1

205300156305501 RB swale, Iao Str near altitude 400 feet, Maui, HI 01/17/2008 0915 0.1-0.2 0.06-0.1

205300156305501 RB swale, Iao Str near altitude 400 feet, Maui, HI 01/18/2008 0905 0.1-0.2 0.06-0.1

205300156305501 RB swale, Iao Str near altitude 400 feet, Maui, HI 02/11/2008 1440 0.005 0.003

205300156305501 RB swale, Iao Str near altitude 400 feet, Maui, HI 02/12/2008 1640 0.005 0.003

205300156305501 RB swale, Iao Str near altitude 400 feet, Maui, HI 02/13/2008 1600 0.01 0.01

205300156305501 RB swale, Iao Str near altitude 400 feet, Maui, HI 02/14/2008 1430 0.01 0.01

205300156305501 RB swale, Iao Str near altitude 400 feet, Maui, HI 02/15/2008 1105 0.01 0.01

205302156305601 Iao Stream near alt 395 ft, Maui, HI 12/14/2006 1631 18.6 12.0

205302156305601 Iao Stream near alt 395 ft, Maui, HI 01/16/2008 0914 28.7 18.6

205302156305601 Iao Stream near alt 395 ft, Maui, HI 01/16/2008 1235 26.8 17.3

205302156305601 Iao Stream near alt 395 ft, Maui, HI 01/17/2008 0812 24.2 15.6

205302156305601 Iao Stream near alt 395 ft, Maui, HI 01/17/2008 1300 23.7 15.3

205302156305601 Iao Stream near alt 395 ft, Maui, HI 01/18/2008 0755 23.0 14.9

205302156305601 Iao Stream near alt 395 ft, Maui, HI 02/11/2008 1230 41.5 26.8

205302156305601 Iao Stream near alt 395 ft, Maui, HI 02/12/2008 1639 36.1 23.3

205302156305601 Iao Stream near alt 395 ft, Maui, HI 02/13/2008 1250 33.7 21.8

205302156305601 Iao Stream near alt 395 ft, Maui, HI 02/13/2008 1440 33.6 21.7

205302156305601 Iao Stream near alt 395 ft, Maui, HI 02/14/2008 1139 31.0 20.0

205302156305601 Iao Stream near alt 395 ft, Maui, HI 02/14/2008 1336 30.4 19.6

205302156305601 Iao Stream near alt 395 ft, Maui, HI 02/15/2008 0747 30.7 19.8

205302156305601 Iao Stream near alt 395 ft, Maui, HI 02/15/2008 0930 30.2 19.5

205302156305601 Iao Stream near alt 395 ft, Maui, HI 02/15/2008 1125 29.7 19.2

205308156304401 Iao Stream near alt 340 ft, Maui, HI 07/25/2006 1046 0.068 0.044

205312156304701 Spring at Iao Stream debris basin wall, Maui, HI 09/21/2004 1618 0.48 0.31

205312156304701 Spring at Iao Stream debris basin wall, Maui, HI 08/29/2008 1206 0.89 0.58

205312156304701 Spring at Iao Stream debris basin wall, Maui, HI 09/25/2008 1548 0.65 0.42

Appendix B 151
Table 12. U.S. Geological Survey miscellaneous discharge measurements during 2004–2009, sorted by Na ̄ Wai ÿEh ̄a 

stream and from upstream to downstream, Maui, Hawaiÿi—Continued.

Site ID Station name Date Time

Cubic feet per 

second

Million gallons 

per day

Discharge

205312156304701 Spring at Iao Stream debris basin wall, Maui, HI 10/23/2008 0954 0.34 0.22

205312156304701 Spring at Iao Stream debris basin wall, Maui, HI 11/18/2008 1646 1.09 0.705

205312156304701 Spring at Iao Stream debris basin wall, Maui, HI 12/05/2008 1212 0.38 0.25

205312156304701 Spring at Iao Stream debris basin wall, Maui, HI 12/19/2008 1058 1.47 0.950

205315156304001 LB spring inflow to Iao Str nr alt 320 ft, Maui, HI 07/25/2006 1009 0.19 0.12

16607000 Iao Stream at Wailuku, Maui, HI 09/21/2004 1658 0.76 0.49

205333156300901 Iao Stream near alt 220 ft, Maui, HI 01/18/2007 0949 18.5 12.0

205333156300901 Iao Stream near alt 220 ft, Maui, HI 02/13/2008 0804 13.2 8.53

205333156300901 Iao Stream near alt 220 ft, Maui, HI 02/13/2008 1101 12.8 8.27

205333156300901 Iao Stream near alt 220 ft, Maui, HI 02/14/2008 0751 9.75 6.30

205333156300901 Iao Stream near alt 220 ft, Maui, HI 02/14/2008 1041 9.50 6.14

205423156292101 Iao Stream near alt 35 ft, Maui, HI 01/18/2007 1227 15.3 9.89

205423156292101 Iao Stream near alt 35 ft, Maui, HI 02/13/2008 0940 10.5 6.79

205423156292101 Iao Stream near alt 35 ft, Maui, HI 02/14/2008 0920 6.52 4.21

205425156291701 Iao Stream near alt 20 ft, Maui, HI 11/15/2006 1126 0.80 0.52

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 08/23/2006 1107 4.08 2.64

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 09/06/2006 1307 3.49 2.26

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 11/13/2006 1141 3.54 2.29

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 12/13/2006 1458 3.73 2.41

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 05/02/2007 1346 3.37 2.18

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 05/03/2007 1308 3.19 2.06

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 07/31/2007 1316 7.73 5.00

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 08/01/2007 1425 3.94 2.55

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 08/02/2007 1337 3.62 2.34

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 09/20/2007 0925 3.31 2.14

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 10/18/2007 0907 4.24 2.74

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 11/15/2007 0933 2.76 1.78

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 12/20/2007 0846 6.00 3.88

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 04/28/2008 1133 3.14 2.03

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 04/29/2008 0947 3.37 2.18

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 04/30/2008 0844 3.36 2.17

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 07/03/2008 0839 2.99 1.93

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 07/29/2008 0930 18.6 12.0

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 08/27/2008 0946 4.41 2.85

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 09/25/2008 1058 2.98 1.93

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 10/22/2008 1032 2.95 1.91

205121156321501 Waikapu Stream near alt 1,160 ft, Maui, HI 12/03/2008 1008 3.08 1.99

205121156320901 Waikapu Str, South Waikapu Ditch intake, Maui, HI 10/28/2004 1235 2.79 1.80

205121156320901 Waikapu Str, South Waikapu Ditch intake, Maui, HI 08/23/2006 1212 2.48 1.60

205121156320901 Waikapu Str, South Waikapu Ditch intake, Maui, HI 11/13/2006 1257 2.47 1.60

205121156320901 Waikapu Str, South Waikapu Ditch intake, Maui, HI 12/13/2006 1425 2.28 1.47

205121156320901 Waikapu Str, South Waikapu Ditch intake, Maui, HI 05/03/2007 1247 3.12 2.02

205121156320901 Waikapu Str, South Waikapu Ditch intake, Maui, HI 08/01/2007 1432 3.31 2.14

205121156320901 Waikapu Str, South Waikapu Ditch intake, Maui, HI 08/02/2007 1344 3.02 1.95

205121156320901 Waikapu Str, South Waikapu Ditch intake, Maui, HI 11/15/2007 1016 2.43 1.57

205122156320901 Waikapu Str, DS of South Waikapu Ditch, Maui, HI 10/28/2004 1141 0.78 0.50

205123156320501 Waikapu Stream near alt 1,080 ft, Maui, HI 08/23/2006 1354 1.17 0.756

205123156320501 Waikapu Stream near alt 1,080 ft, Maui, HI 11/13/2006 1346 0.82 0.53

205123156320501 Waikapu Stream near alt 1,080 ft, Maui, HI 12/13/2006 1349 1.06 0.685

205123156320501 Waikapu Stream near alt 1,080 ft, Maui, HI 12/13/2006 1521 1.54 1.00

205123156320501 Waikapu Stream near alt 1,080 ft, Maui, HI 05/03/2007 1209 0.27 0.17

205123156320501 Waikapu Stream near alt 1,080 ft, Maui, HI 07/31/2007 1220 3.44 2.22

205123156320501 Waikapu Stream near alt 1,080 ft, Maui, HI 08/01/2007 1340 0.99 0.64

205123156320501 Waikapu Stream near alt 1,080 ft, Maui, HI 08/02/2007 1010 0.90 0.58

205123156320501 Waikapu Stream near alt 1,080 ft, Maui, HI 09/20/2007 1121 0.48 0.31

205123156320501 Waikapu Stream near alt 1,080 ft, Maui, HI 10/18/2007 0901 1.23 0.795

205123156320501 Waikapu Stream near alt 1,080 ft, Maui, HI 11/15/2007 1028 0.51 0.33

205123156320501 Waikapu Stream near alt 1,080 ft, Maui, HI 12/20/2007 0940 2.50 1.62

205123156320501 Waikapu Stream near alt 1,080 ft, Maui, HI 04/28/2008 1318 0.61 0.39

205123156320501 Waikapu Stream near alt 1,080 ft, Maui, HI 04/30/2008 0940 0.12 0.078

205123156320501 Waikapu Stream near alt 1,080 ft, Maui, HI 07/03/2008 0947 0.092 0.059

Waikapü Stream

152 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Table 12. U.S. Geological Survey miscellaneous discharge measurements during 2004–2009, sorted by Nä Wai ÿEhä 

stream and from upstream to downstream, Maui, Hawaiÿi—Continued.

Site ID Station name Date Time

Cubic feet per 

second

Million gallons 

per day

Discharge

205123156320501 Waikapu Stream near alt 1,080 ft, Maui, HI 07/29/2008 1135 9.40 6.08

205123156320501 Waikapu Stream near alt 1,080 ft, Maui, HI 08/27/2008 1042 0.55 0.36

205123156320501 Waikapu Stream near alt 1,080 ft, Maui, HI 09/25/2008 0950 0.095 0.061

205123156320501 Waikapu Stream near alt 1,080 ft, Maui, HI 10/22/2008 0910 0.15 0.10

205123156320501 Waikapu Stream near alt 1,080 ft, Maui, HI 12/03/2008 0904 0.13 0.084

205122156320601 Waikapu Str, South Waikapu Dt overflow, Maui, HI 10/28/2004 1345 0.07 0.05

205124156320301 RB inflow to Waikapu Str nr alt 1,070 ft, Maui, HI 08/23/2006 1437 0.02 0.01

205124156320301 RB inflow to Waikapu Str nr alt 1,070 ft, Maui, HI 05/03/2007 1415 0.05-0.1 0.03-0.06

205124156320301 RB inflow to Waikapu Str nr alt 1,070 ft, Maui, HI 07/31/2007 — 0.005-0.01 0.003-0.006

205124156320301 RB inflow to Waikapu Str nr alt 1,070 ft, Maui, HI 08/01/2007 1330 0.005-0.01 0.003-0.006

205124156320301 RB inflow to Waikapu Str nr alt 1,070 ft, Maui, HI 11/15/2007 1122 0.1-0.15 0.06-0.1

205124156320301 RB inflow to Waikapu Str nr alt 1,070 ft, Maui, HI 04/30/2008 1008 0.1-0.2 0.06-0.1

205124156320301 RB inflow to Waikapu Str nr alt 1,070 ft, Maui, HI 07/03/2008 1050 0.1 0.06

205125156320101 Waikapu Str US unnamed trib at 1,060 ft, Maui, HI 10/28/2004 1450 0.62 0.40

205122156320101 Unnamed Trib to Waikapu Str at 1,060 ft, Maui, HI 10/28/2004 1408 2.27 1.47

205122156320101 Unnamed Trib to Waikapu Str at 1,060 ft, Maui, HI 05/03/2007 1538 1.80 1.16

205122156320101 Unnamed Trib to Waikapu Str at 1,060 ft, Maui, HI 08/01/2007 1536 1.68 1.09

205122156320101 Unnamed Trib to Waikapu Str at 1,060 ft, Maui, HI 08/02/2007 1459 1.64 1.06

205122156320101 Unnamed Trib to Waikapu Str at 1,060 ft, Maui, HI 09/20/2007 1230 1.58 1.02

205122156320101 Unnamed Trib to Waikapu Str at 1,060 ft, Maui, HI 11/15/2007 1134 1.53 0.989

205122156320101 Unnamed Trib to Waikapu Str at 1,060 ft, Maui, HI 04/29/2008 0940 2.02 1.31

205122156320101 Unnamed Trib to Waikapu Str at 1,060 ft, Maui, HI 04/30/2008 0835 1.98 1.28

205122156320101 Unnamed Trib to Waikapu Str at 1,060 ft, Maui, HI 07/29/2008 1332 1.82 1.18

205122156320101 Unnamed Trib to Waikapu Str at 1,060 ft, Maui, HI 08/27/2008 1138 1.76 1.14

205122156320101 Unnamed Trib to Waikapu Str at 1,060 ft, Maui, HI 09/25/2008 1246 1.85 1.20

205122156320101 Unnamed Trib to Waikapu Str at 1,060 ft, Maui, HI 10/22/2008 1138 1.65 1.07

205122156320101 Unnamed Trib to Waikapu Str at 1,060 ft, Maui, HI 12/03/2008 1118 1.76 1.14

205126156315501 Waikapu Stream near alt 1,020 ft, Maui, HI 08/23/2006 1546 3.25 2.10

205126156315501 Waikapu Stream near alt 1,020 ft, Maui, HI 12/13/2006 1223 3.42 2.21

205126156315501 Waikapu Stream near alt 1,020 ft, Maui, HI 12/13/2006 1608 3.96 2.56

205126156315501 Waikapu Stream near alt 1,020 ft, Maui, HI 05/03/2007 1141 2.09 1.35

205126156315501 Waikapu Stream near alt 1,020 ft, Maui, HI 08/01/2007 1318 3.10 2.00

205126156315501 Waikapu Stream near alt 1,020 ft, Maui, HI 11/15/2007 1150 2.19 1.42

205122156314701 Waikapu Stream near alt 950 ft, Maui, HI 12/13/2006 1126 3.16 2.04

205122156314701 Waikapu Stream near alt 950 ft, Maui, HI 12/13/2006 1621 3.41 2.20

205122156314701 Waikapu Stream near alt 950 ft, Maui, HI 05/03/2007 1037 2.27 1.47

205122156314701 Waikapu Stream near alt 950 ft, Maui, HI 08/01/2007 1249 2.56 1.65

205122156314701 Waikapu Stream near alt 950 ft, Maui, HI 11/15/2007 1252 1.68 1.09

205122156314701 Waikapu Stream near alt 950 ft, Maui, HI 04/29/2008 1102 4.93 3.19

205122156314701 Waikapu Stream near alt 950 ft, Maui, HI 04/30/2008 0955 1.99 1.29

205124156314301 RB inflow to Waikapu Str nr alt 925 ft, Maui, HI 11/15/2007 1340 0.1-0.15 0.06-0.1

205124156314301 RB inflow to Waikapu Str nr alt 925 ft, Maui, HI 04/30/2008 1020 0.1 0.06

16649000 04/29/2008 1204 0.56 0.36

16649000 04/30/2008 1114 0.21 0.14

16650000 10/28/2004 1535 3.11 2.01

205120156312801 Waikapu Stream near alt 820 ft, Maui, HI 09/06/2006 1522 2.38 1.54

205120156312801 Waikapu Stream near alt 820 ft, Maui, HI 05/02/2007 0849 4.06 2.62

205120156312801 Waikapu Stream near alt 820 ft, Maui, HI 05/03/2007 1039 3.83 2.48

205120156312801 Waikapu Stream near alt 820 ft, Maui, HI 08/01/2007 0846 2.96 1.91

205120156312801 Waikapu Stream near alt 820 ft, Maui, HI 09/20/2007 1350 2.13 1.38

205120156312801 Waikapu Stream near alt 820 ft, Maui, HI 10/18/2007 1136 2.62 1.69

205120156312801 Waikapu Stream near alt 820 ft, Maui, HI 11/15/2007 1240 1.78 1.15

205120156312801 Waikapu Stream near alt 820 ft, Maui, HI 12/20/2007 1110 3.96 2.56

205120156312801 Waikapu Stream near alt 820 ft, Maui, HI 04/28/2008 1452 3.02 1.95

205120156312801 Waikapu Stream near alt 820 ft, Maui, HI 04/29/2008 1210 4.76 3.08

205120156312801 Waikapu Stream near alt 820 ft, Maui, HI 04/30/2008 1041 1.95 1.26

205120156312801 Waikapu Stream near alt 820 ft, Maui, HI 07/29/2008 1426 8.09 5.23

205120156312801 Waikapu Stream near alt 820 ft, Maui, HI 07/30/2008 0821 3.01 1.95

205120156312801 Waikapu Stream near alt 820 ft, Maui, HI 08/27/2008 0831 2.90 1.87

205120156312801 Waikapu Stream near alt 820 ft, Maui, HI 09/25/2008 1402 1.95 1.26

205120156312801 Waikapu Stream near alt 820 ft, Maui, HI 09/26/2008 0804 1.82 1.18

205120156312801 Waikapu Stream near alt 820 ft, Maui, HI 10/22/2008 1312 1.84 1.19

PALOLO DITCH NEAR WAIKAPU,MAUI,HI

PALOLO DITCH NEAR WAIKAPU,MAUI,HI

WAIKAPU STREAM NEAR WAIKAPU,MAUI,HI

Appendix B 153
Table 12. U.S. Geological Survey miscellaneous discharge measurements during 2004–2009, sorted by Nä Wai ÿEhä 

stream and from upstream to downstream, Maui, Hawaiÿi—Continued.

Site ID Station name Date Time

Cubic feet per 

second

Million gallons 

per day

Discharge

205120156312801 Waikapu Stream near alt 820 ft, Maui, HI 12/03/2008 1200 1.72 1.11

205125156304801 Waikapu Str, US of left bank taro intake, Maui, HI 10/28/2004 1200 2.92 1.89

205125156304801 Waikapu Str, US of left bank taro intake, Maui, HI 09/06/2006 1000 2.06 1.33

205125156304801 Waikapu Str, US of left bank taro intake, Maui, HI 12/13/2006 0858 3.09 2.00

205125156304801 Waikapu Str, US of left bank taro intake, Maui, HI 05/03/2007 0859 3.60 2.33

205125156304801 Waikapu Str, US of left bank taro intake, Maui, HI 08/01/2007 1711 2.27 1.47

205125156304801 Waikapu Str, US of left bank taro intake, Maui, HI 04/28/2008 1706 2.52 1.63

205125156304801 Waikapu Str, US of left bank taro intake, Maui, HI 04/29/2008 1355 4.29 2.77

205125156304801 Waikapu Str, US of left bank taro intake, Maui, HI 04/30/2008 1226 1.35 0.873

205124156304401 Waikapu Str, left bank taro diversion, Maui, HI 10/28/2004 1310 1.02 0.659

205123156304201 Waikapu Str, left bank taro div overflow, Maui, HI 10/28/2004 1406 0.46 0.30

205121156304001 Waikapu Str, left bank taro return, Maui, HI 10/28/2004 1008 0.19 0.12

205118156302901 Waikapu Str, right bank inflow, Maui, HI 10/28/2004 1531 0.20 0.13

205116156302601 Waikapu Str US of Waihee Ditch intake, Maui, HI 10/28/2004 1602 2.77 1.79

205114156302301 Waikapu Str DS of Waihee Ditch, Maui, HI 10/28/2004 1711 0.60 0.39

205112156301601 Waikapu Str US of Reservoir 6 intake, Maui, HI 10/28/2004 1650 1.10 0.711

205112156301201 Waikapu Stream near alt 400 ft, Maui, HI 08/22/2006 0850 4.03 2.60

205112156301201 Waikapu Stream near alt 400 ft, Maui, HI 04/02/2007 1742 7.40 4.78

205112156301201 Waikapu Stream near alt 400 ft, Maui, HI 01/29/2009 1144 25.0 16.2

205112156301202 Waikapu Stream near alt 400 ft, Maui, HI 03/13/2009 1120 14.2 9.18

16650200 Waikapu Stream at Waikapu, Maui, HI 03/18/2004 1101 16.3 10.5

205040156292801 Waikapu Stream near alt 225 ft, Maui, HI 08/22/2006 1000 0 0

205024156292301 Waikapu Stream at Route 380 bridge, Maui, HI 10/28/2004 1730 0 0

205024156292301 Waikapu Stream at Route 380 bridge, Maui, HI 08/21/2006 1458 0.24 0.16

205024156292301 Waikapu Stream at Route 380 bridge, Maui, HI 04/02/2007 1650 5.63 3.64

204850156284901 Waikapu Str at lower Maalaea Rd nr Maalaea,Maui,HI 03/18/2004 0955 7.10 4.59

204850156284901 Waikapu Str at lower Maalaea Rd nr Maalaea,Maui,HI 01/29/2009 1008 18.2 11.8

204850156284901 Waikapu Str at lower Maalaea Rd nr Maalaea,Maui,HI 01/29/2009 1249 13.9 8.98

204850156284901 Waikapu Str at lower Maalaea Rd nr Maalaea,Maui,HI 03/13/2009 0938 8.27 5.35

204850156284901 Waikapu Str at lower Maalaea Rd nr Maalaea,Maui,HI 03/13/2009 1240 6.92 4.47

204827156283601 Waikapu Stream at alt. 30 ft near Kihei, Maui, HI 03/18/2004 1054 5.74 3.71

154 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄
Produced in the Western Region, Menlo Park, California

Manuscript approved for publication, January 6, 2010

Text edited by Peter H. Stauffer

Layout and design by Stephen L. Scott
156 Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄

Oki and others—Effects of Surface-Water Diversion on Streamflow, Recharge, Physical Habitat, and Temperature, Na ̄ Wai ÿEha ̄, Maui—Scientific Investigations Report 2010–5011