Hydrology of the Upper 

Malad River Basin, 

Southeastern Idaho

By E. J. PLUHOWSKI

GEOLOGICAL SURVEY WATER-SUPPLY PAPER 1888

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1970
UNITED STATES DEPARTMENT OF THE INTERIOR 

WALTER J. HIGKEL, Secretary

GEOLOGICAL SURVEY 

William T. Pecora, Director

Library of Congress catalog-card No. 73-604793

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402 - Price 45 cents
CONTENTS

Page

Abstract. _________-__-_-----_-------____-____-___________________ 1

Introduction._____________________________________________________ 2

Purpose.___-_-___---------------_---_-_-_---_____________-_-_ 2

Location and extent of area.-__-_-__________-_--_-_-_-_________ 3

Previous investigations._______________________________________ 3

Well-numbering system________________________________________ 5

Geography. ______-_____-_--____-__-__--__-_---_-_-___-____-__-_-- 6

Population ___________________________________________________ 6

Topography and drainage.____-__________--__-_____-_______---- 7

Agriculture and irrigation_________________-__-_-___-___-_------ 9

Vegetation. ___-______________-_________-_-_---_-_-___-___---_ 11

Climate._________________-___-_____..__----_---------_------_----- 11

Primary controls.____________-__-_-_-___-_---_--____---__---__ 11

Temperature. ___________________________-_-----__---_-___--_- 14

Seasonal variations._______________________________________ 14

Vertical temperature gradient-____________-----_-------__--- 16

Hydrometeorology _ ____________________________--_-_-_-_-------_-_ 18

Circulation patterns favoring above-normal precipitation ________ 18

Persistence of circulation patterns.______________________---_--_- 20

Cold-season drought.__________________-__--__--_--------__ 22

Warm-season drought_____-_________------------------_-_- 22

Precipitation intensity and distribution__________-___-----_-_--__ 24

Quantitative hydrology_____________________-__--_---_--_------_-_ 27

Area precipitation.______-_-_____________-_-_-__--_------------ 27

Evaporation.___________________________________ ___---_-__--_ 30

Evapotranspiration. _______________________-_-___---_____------ 31

Water yield..._.___.___.___._._..___.__._ ________.._._.___.. 32

Ground water_____________________________________________________ 38

Geology in relation to ground water.____________________________ 38

The ground-water reservoir.______-_______-___-_____------------ 39

Recharge. __________-________________________--__-__-_------__ 41

Movement__ ________________________________________________ 44

Discharge.___________________________________________________ 45

Underflow- ____________________________________________________ 49

Surface water.____________________________________________________ 51

Low-flow characteristics of streams._____________________________ 53

Monthly discharge summary._______________________________ 55

Flow-duration curves__-_----_________-__--___----_--_---- 58

Low-flow frequency curves________________________________ 60

Days of deficient discharge_____..______________-____--_---- 61

Storage-required frequency _________________________________ 62

in
IV CONTENTS

Surface water Continued

Floods._______________________________

Flood frequency.__________________

Plotting position._________________

Mean annual flood____--_--_-______

Regional flood frequency.__________

Water quality.._______________________

Stream temperature.___________________

Grain-size distribution in stream channelsWater management. -__-___-_-__-__________

Summary and conclusions._________________

References cited.___--_-__-_-________.____.

Index.__----_-_--_-_-_-_______--_________

Page 

65 

68 

68

68

69

71

75

78

80

82

84

87

ILLUSTEATIONS

Page 

FIGURE 1. Index map of southeastern Idaho showing location of

area of investigation._____________________________ 4

2. Diagram showing well-numbering system._____________ 5

3. Generalized landform map__--_____-_--__-_-_-___-_ 8 

4-7. Graphs:

4. Area-altitude relation_______________________ 9

5. Variation of average monthly temperature and

precipitation at Malad City__-_-___--__-___- 13

6. Air temperature duration.____________________ 15

7. Regional lapse rate____________-____.____--- 17

8. Maps showing 700-millibar surface and resulting precipitation, January 1956 and August 1951.__________ 19

9. Graph of annual precipitation, Malad City and Pocatello. 21

10. Maps showing 700-millibar surface and resulting precipitation, February 1953 and June 1951 ____________ 23

11. Curves showing annual precipitation duration at Malad

City_____._--______._._-__-____----------_------ 25

12. Graph of hourly precipitation frequency at Pocatello.--- 26

13. Regional precipitation curves--_----__--------------_ 28

14. Map showing mean annual precipitation.-------.--.--- 29

15. Graph showing relation of water yield to prec'oitation

and potential evapotranspiration___________-___-_-- 33

16. Map showing mean annual water yield-_______________ 36

17. Graph depicting regional precipitation and water yield. _ 37

18. Generalized geologic map__--------------_----------- 40

19. Cross section showing generalized logs of selected wells __ 42
CONTENTS V

FIGURES 20-23. Graphs: Page

20. Soil particle-size distribution.-___--_--_______________ 43

21. Hydrographs of wells_______________________._______ 46

22. Streamflow along the Little Malad River and Deep

Creek.--_---__-_-_--_____-_-_____-_____-..._____ 47

23. Length of stream-gaging records____________________ 52

24. Map showing location of stream-gaging sites and weather

stations.________________________________________ 54

25-32. Graphs:

25. Duration, Devil Creek above Campbell Creek________ 59

26. Low-flow frequency, Devil Creek above Campbell Creek. 60

27. Deficient discharge frequency, Devil Creek above Campbell Creek_________-__________________.-.--______ 62

28. Frequency-mass curves, Devil Creek above Campbell

Creek._.____-_-____._.___-________________ 63

29. Allowable draft frequency, Devil Creek above Campbell

Creek._______-__---_-__---_--______--___________ 64

30. Weather conditions at Malad City and hydrograph for

Malad River at Woodruff_____.-________._________ 67

31. Flood frequency ___________________________________ 69

32. Relation of mean annual flood to drainage area._______ 70

33. Map showing chemical quality of surface water. _______ 74

34. Graph of air and stream temperatures._______________ 77

35. Graphs showing streambed grain-size distribution. _____ 79

TABLES

Page 

TABLE 1. Maximum recorded precipitation intensities at Malad

City, 1940-62--___-_.____-__--------------------- 27

2. Rainfall intensity for selected frequencies and time

durations at Malad City______-------------------- 27

3. Mean monthly land-pan evaporation from selected

stations._____-___________________--_------__---- 30

4. Streamflow measurement sites along the Little Malad

River and Deep Creek______________--_-------__-- 48

5. Monthly streamflow characteristics of selected gaging

stations.___________________________-__._-------- 57

6. Duration of daily flow at selected stations, adjusted to

base period, 1932-59----_-_--_-------------------- 59

7. Low-flow frequency at selected stations, adjusted to base

period, 1932-59---------------------------------- 61

8. Annual low-flow frequency for days of deficient discharge

at selected stations, adjusted to base period, 1932-59-- 63

9. Storage-required frequency for selected stations, adjusted

to base period, 1932-59--------------------------- 65

10. Peak discharges at selected gaging stations.___-____-_- 71 

11 Chemical analyses of water from selected stream sites in the

upper Malad River basin______________---__------- 73
HYDROLOGY OF THE UPPER MALAD RIVER BASIN, 

SOUTHEASTERN IDAHO

By E. J. PLUHOWSKI

ABSTRACT

The report area comprises 485 square miles in the Basin and Range physiographic province. It includes most of eastern' Oneida County and parts of Franklin, Bannock, and Power Counties of southeastern Idaho. Relief is about 5,000 

feet; the floor of the Malad Valley is at an average altitude of about 4,400 feet. 

Agriculture is, by far, the principal economic activity. In 1960 the population 

of the upper Malad River basin was about 3,600, of which about 60 percent 

resided in Malad City, the county seat of Oneida County.

The climate is semiarid throughout the Malad Valley and its principal tributary 

valleys; above 6,500 feet the climate is subhumid. Annual precipitation ranges 

from aibout 13 inches in the lower Malad Valley to more than 30 inches on the 

highest peaks of the Bannock and Malad ranges. Owing to the normally clear 

atmospheric conditions, large daily and seasonal temperature fluctuations are 

common. Topography, distance from the Pacific Ocean, and the general atmospheric circulation are the principal factors governing the climate of the Malad 

River basin. The westerlies transport moisture from the Pacific Ocean toward 

southeastern Idaho. The north-south trending mountains flanking the barm are 

oriented orthogonally to the moisture flux so that they are very effective in 

removing precipitable water from the air. A minimum uplift of 6,000 feet is 

required to transport moisture from the Pacific source region; accordingly, most 

air masses are desiccated long before they reach the Malad basin. Heaviest precipitation is generally associated with steep pressure gradients in th^ midtroposphere that are so oriented as to cause a deep landward penetration of 

moisture from the Pacific Ocean.

Annual water yields in the project area range from about 0.8 inch in the lower 

Malad Valley to more than 19 inches on the high peaks north and east of Malad 

City. The mean annual water yield for the entire basin is 4 inches, or about 

115,000 acre-feet. Evaporation is greatest in July when about 7 inches is lost 

from lakes, reservoirs, and waterlogged areas; losses from free-water surfaces 

may be as much as 38 inches annually.

An extensive ground-water reservoir consiting of sand and gravel inter^edded 

with relatively impermeable beds of silt and clay underlies much of the Malad 

Valley. Wells near the center of the valley exceeding 700 feet in depth do not 

reach bedrock. The Woodruff fault, which transects the constricted lower Malad 

Valley, is one of the main factors creating artesian conditions south of the latitude 

of Malad City. Recharge is obtained principally from mountain runoff which flows 

onto highly permeable alluvial fans surrounding the valley and from streams
2 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

that flow across the valley floor. On the basis of a \v<a tor-balance analysis, under 

flow from the project area was estimated to be 28,000 acre-feet annually, surfacewater outflow was 51,000 acre-feet, and transbasin imports were about 4,000 

acrenfeet.

The principal tributaries of the Malad River are perennial along their upper 

and middle reaches and have well-sustained low flows. During the growing season, 

all surface waiter entering the Malad Valley is used for irrigatior. Some irrigation is practiced in the principal tributary valleys; however, a shortage of 

suitable reservoir sites has hampered surface-water development in these areas. 

The highly porous deposits underlying the Malad Valley tend to attenuate flood 

peaks. An unusual combination of meteorologic events early in 1962 effectively 

counteracted the high absorptive capacity of the valley and predisposed the 

basin to high flood risk. Subsequent rapid snowmelt combine 1 with frozen 

ground produced 'the extraordinary flood of February 12, 1962.

Calcium and bicarbonate commonly are the most abundant ions in the surface 

waters of the upper Malad River basin. In August 1967, the dissolved-solids 

content of streamflow ranged from 200 to 350 milligrams per liter in the middle 

and upper parts of the basin; however, much greater values were measured in 

the Malad River between Woodruff and Cherry Creek Lane. Witl the exception 

of that reach, the surface water of the project area is suitable fo*" irrigating all 

but the most sensitive crops.

The total water yield is not sufficient to meet all the water needs of the basin. 

A comprehensive water-management plan Is required to ensure optimal use 

of the water resource.

INTRODUCTION

PURPOSE

The upper Malad River basin is an agricultural region whose economy depends largely on irrigation. Although annual precipitation on 

the valley floor is marginal even in wet years, moderate precipitation 

on the surrounding highlands yields sufficient runoff to supply much 

of the basin's water needs. Overland runoff from, tl ^ hard-rock 

uplands spills onto the permeable valley floor where part of it filters 

into the ground. Some of the water that seeps into the ground percolates through the zone of aeration and eventually merges with the 

ground-water reservoir. Irrigation for the production of high-value 

cash crops is provided by diverting streams into ditches and by pumping from the extensive ground-water reservoir underlying the Malad 

Valley.

Despite the generally favorable situation, the basin i? not without 

its problems with regard to water. Heavy pumping of artesian aquifers 

underlying the southern part of the valley has lowered pressures to 

such an extent that many wells which once flowed freely no longer 

do so, and the discharge of flowing wells has diminished. The density 

of water-loving plants has increased in much of the lower part of the 

valley owing to irrigation from numerous flowing wells. Large tracts 

south of Malad City are unsuitable for agriculture beer use of heavy
INTRODUCTION 6

concentrations of salt and alkali in the soils especially in areas of 

ground-water discharge.

The purpose of this report is to evaluate the hydrologic factors that 

directly or indirectly affect the water balance of the upper Malad River 

basin. Specifically, an attempt is made to assess the water yield of the 

basin. Surface-water supplies are evaluated, and methods of increasing 

the beneficial use of water in the basin are suggested.

LOCATION AND EXTENT OF AREA

The study area comprises the 485-square-inile drainage area of the 

Malad River above Woodruff, Idaho. It includes most of eastern 

Oneida County and parts of Franklin, Bannock, and Power Counties 

of southeastern Idaho (fig. 1). Malad City, the principal town in the 

basin, is about 50 miles south of Pocatello, Idaho, and about 100 miles 

north of Salt Lake City, Utah.

The Malad Valley is bounded on the east by the Bannock and the 

Malad Ranges and on the west and southwest by the Blue Spring Hills 

(fig. 3). On the north the valley is divided into two principal drainage 

systems which are separated by a spur of the Bannock Range. South 

of the spur much of the valley is underlain by an artesian aquifer. 

The principal axis of the basin trends northward and is about 37 

miles in length; the basin is about 24 miles across at its widest point.

PREVIOUS INVESTIGATIONS

One of the earliest accounts of the geology and landforms of the 

upper Malad River basin was made by Bradley (1873). Peale (1879) 

described the limestone formations which crop out in the Blue Spring 

Hills. Several of the principal stratigraphic units of the basin were 

defined by Piper (1924). The Woodruff fault, which trends eastward 

across the constricted south end of the Malad Valley, was described 

in a report by Mower and Nace (1957). That report contains a description of the geology of the basin in relation to the ground-water 

reservoir.

Thompson and Faris (1932) measured the discharge from artesian 

wells south of Malad City in 1931. They made a preliminary evaluation of the water resources of the basin and recommended that surface 

supplies be used in the spring and early summer and that ground 

water be reserved for use during periods of low flow. This suggestion 

was made to conserve water by improving the efficiency of water use 

in the basin. Livingston and McDonald (1943) estimated the total 

flow from artesian wells to be 6,000 gpm (gallons per minute) in the 

Malad Valley during July 1943. They measured considerable subsur367-852 0 70 2
4 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

face migration of water through uncapped or leaky artesian wells. 

Mower and Nace (1957) estimated evapotranspiration losses from 

the middle and lower parts of the Malad Valley to be about 37,000 

acre-feet a year. Water-level measurements for some observation 

wells, records of daily discharge for gaging stations, and discharge 

measurements made at partial-record sites are published in annual 

water-supply papers .and open-file reports of the U.S. Geological 

Survey.

114°

45

44

43'

42°

113° 112°

Rupert

MONTANA

IDAHO

St. Anthony I

O

IS i£

CARIBC U

Soda Springs

( __ ^

UTAH

50 MILES

FIGUKE 1. Map of southeastern Idaho showing area of investigation.
INTRODUCTION

WELL-NUMBERING SYSTEM

Water wells are designated in this report by numbers which indicate 

their locations within legal rectangular subdivisions of the public 

lands, with reference to the Boise base line and meridian. The fir^t two 

elements of a number designate the township and range. The third 

element is the section number, followed by two lower-case letters and 

a numeral. The first of the two letters indicates the quarter section and 

the second the tract. Quarter sections are lettered a, b, c, and d in 

counterclockwise order, from the northeast quarter of each section. 

Within the quarter sections 40-acre tracts are lettered in the same 

manner. For example, well 14S-35E-13dbl is the first well visited 

in the NW^SE^ sec. 13, T. 14 S., K. 35 E. The method of numbering is illustrated in figure 2.

R 1 E.

BASE LINE

34 35 36 R 37 E

WELL 14S-35E-13dbl

R 35 E

6

7

18

19

30

31

5

8

17

20

29

32

4

9

16

21

28

33

3

10

15

22

27

34

2

11

14

23

26

35

1

12 1

13cL

24

25

36

FIGUBE 2. Well-numbering system.
6 HYDROLOGY, TIPPER MALAD RIVER BASIN, IDAHO

GEOGRAPHY 

POPULATION

The Malad Valley was first settled in 1855, but the settlement disbanded in 1858 owing to the destruction of crops by locurts. The first 

permanent settlement of the Malad Valley was established in 1864 at 

the site of what is now Malad City (Howell, 1960). In 1866 the Oneida 

County seat was moved from Soda Springs to Malad City which 

helped spur the growth of the town. By 1870, Malad City had a population of 571, and it continued to grow steadily for another 50 years. 

Owing to a good perennial supply of wrater, wild game, fertile lands, 

and an adequate supply of timber nearby, the valley was largely settled 

by the turn of the century. A railroad, built in 1906, stimulated population growth by connecting the expanding agricultural economy of 

the Malad Valley with the large population centers of Ogden and Salt 

Lake City, Utah. The population of the basin continued to increase 

until shortly after World War I.

After the boom years of World War I, the population of the study 

basin followed the downward trend of many other farm-based economies in the Nation. The population of Oneida County, for example, 

has declined steadily since 1920. By 1960, the countywide population 

was only 54 percent of the 1920 population as shown in tl °, following 

table:

Population of Malad City and Oneida County, Idaho

I960 1950 1940 1930 1920 1910 1900

Malad City....................................... 2,274 2,715 2,731 2,535 3,OfO 1,904 1,360

Oneida County................................... 3,603 4,387 5,417 5,870 6,723 ................

Malad City, on the other hand, showed substantial growth between 

1900 and 1920. After a decline in population during the 1920's some 

recovery occurred during the 1930's; however, since 1950 its population has declined again. Much of the increase in the population of 

Malad City during 1900-50 probably resulted from a tendency on the 

part of farmers to move into town as improved roads and automobiles 

reduced travel time between town and farm. The countywide decline 

in population can be ascribed to an exodus of people to large urban 

centers and a growing tendency toward larger farms. Improved mechanization has greatly increased the acreage which a farmer can successfully cultivate. Efficient farms grow at the expense of less efficient 

enterprises; thus, the basin has fewer farms today than at any time 

since 1900.
GEOGRAPHY 7 

TOPOGBAPHY AND DBAINAGE

The upper Malad River basin is in the Basin and Range physiographic province (Fenneman, 1931). Extreme relief is about 5,000 

feet. The average altitude of the Malad Valley floor is about 4,400 

feet, and it ranges from about 4,350 feet at Woodruff to 4,800 feet 

where the valley abuts the surrounding highlands. The Malad T7"alley 

has low relief and is about 7 miles wide and 11 miles long. About 3 

miles above Woodruff the valley abruptly narrows to a width c f 2 to 

3 miles, and this constricted cross section is maintained southward 

into Utah. Highest altitudes are 9,285 feet at Oxford Peak and 9,001 

feet at Mount Elkhorn. Both peaks are part of the Bannock Range 

which forms the northern and, with the Malad Range, the eastern 

boundaries of the study basin (figure 3). In the Blue Spring Hills 

to the west, the highest peaks are less than 8,000 feet. The mean altitude of the basin is 5,600 feet (fig 4), and only 6 percent of the r.rea is 

above 7,000 feet in altitude.

The mountain ranges are oriented north-south, and their crests form 

the boundaries of the basin everywhere except across the constricted 

lower Malad Valley. In general, the uplands are well dissected by 

numerous ephemeral channels which have eroded sharp V-shaped valleys. Both the mountains and their surrounding foothills are being 

degraded by a combination of sheet wash, gullying, and channel 

erosion.

The products of the upland erosion have formed alluvial fans 

at the base of the foothills. Upon flowing onto the alluvial fans the 

competence of streams to move sediment is quickly reduced. This 

is due principally to lower gradients and the rapid infiltration of 

streamflow into the pervious bed material. As a result of the combination of discharge loss and sediment deposition, most ephemeral 

channels lose their identity a short distance beyond the foothills. 

The slopes of the alluvial fans gradually decrease until they merge 

with the valley floor.

In general, the principal tributary basins, the Little Malad River 

and Devil and Deep Creeks, are well dissected and characterized by 

moderate gradients and narrow flood plains. These streams ore perennial north of the Malad Valley and are sustained by springs and 

transbasin diversions. The flow in all streams that move acrcss the 

Malad Valley is generally sluggish owing to the predominantly 

gentle gradients. The Malad River, whose source is a spring on the 

valley floor north of Pleasantview, flows entirely within the western 

part of the Malad Valley; consequently its gradient is low and its 

course is meandering. Bank erosion may be severe during high-flow 

periods in all stream channels traversing the Malad Valley. Highly
HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

EXPLANATION

R 34 E

U|« 

«ft

T. 10 S

42°30' =

T. 11 S

Valley floor Alluvial fans

Includes flood plains of the _____

principal tributary valleys \S\\~-\-\i

and alluvial and lacustrine CsVvvl

plain,, of the Malad Valley Dissected uplands

Local relief generally less 

than 1,500 feet

Dissected uplands

Local relief generally greater 

than 1,500 feet

Spring

T 12S

T. 13 S

T. 14 5

T.15S

T. 16 S

. Generalized landforni map of the upper Malad Riv?r basin.
GEOGRAPHY

9000

8000

7000

6000

5000

4000

0 20 40 60 80 

PERCENTAGE OF DRAINAGE AREA ABOVE INDICATED ALTITUDE

100

FIGURE 4. Area-altitude curve for the upper Malad River basin.

erodible fine-grained material along the banks of the Little Malad 

River and Deep and Wright Creeks results in locally severe channel 

trenching and bank cutting of as much as 15 feet below the adjacent 

plains. After leaving the study area, the Malad Eiver flows southward into Utah where it joins the Bear River which empties into 

the Great Salt Lake.

AGRICULTURE AND IRRIGATION

According to the 1959 census by the U.S. Department of Agriculture, of the total harvested acreage of 120,000 acres in the upper 

Malad River basin, nearly 22,000 acres is irrigated. The three largest
10 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

cash crops are winter wheat (1,280,000 bushels), barley (872,000 

bushels), and spring wheat (186,000 bushels); potatoes and sugar 

beets are the principal irrigated row crops. In addition, extensive 

tracts are devoted to the production of hay and forage crops, particularly in the Malad Valley. A substantial part of total farm income 

is obtained from the sale of cattle and sheep.

Agricultural development in the Malad Valley was b°gun in the 

mid-1860's. Within a short time nearly the entire flow of streams in 

the valley was being diverted for irrigation during the growing 

season. Desirable lands adjacent to the streams were quickly brought 

under irrigation and further expansion of irrigated r<?reage was 

slow. Following the appropriation of most surface-water supplies, 

dry-land farming of wheat and barley was attempted successfully 

on the foothills surrounding the Malad Valley and in its principal 

tributary valleys. About 1900 the large potential yield of the artesian 

basin in the southern part of the valley was recognized. Flowing 

wells were drilled in a wide area south of Malad City and much 

new land was brought under irrigation. Development of nonartesian 

water with pumped wells was begun about 1930, and substantial areas 

of land north and west of Malad City are irrigated with water from 

pumped wells. To augment surface-water supplies, a large part of 

the headwater flow of Birch Creek in the Snake River basin was 

diverted into Devil Creek. This imported water is the principal 

supply for much of the irrigated land in Devil Creek valley and the 

part of the Malad Valley lying north of Malad City. Small storage 

reservoirs have been constructed on Deep Creek, Davis Creek, and 

the Little Malad River. Currently (1967) a new reservoir is being 

constructed on the Little Malad River near Daniels, about 3i/£ miles 

above Elkhorn Dam.

Surface-water users in the Malad Valley recognized early the need 

for careful management of the comparatively small quantity of water 

that is available to them. They are, moreover, aware tha.t much improvement in surface-water management is possible by employing more 

efficient engineering and land-use practices. In contrast to the cooperative efforts with regard to surface water, development and use of 

ground water has been uncoordinated and without much regard to the 

overall water economy of the valley. Waste of ground water, especially 

from flowing wells, commonly occurs with little action taken by well 

owners to limit waste. Widespread declines of piezometric levels in the 

artesian aquifers may, in part, be traced to the haphazard and inefficient use of the valley's ground-water resources. Owing to excessive 

application and waste of water on some tracts of land, other tracts of 

arable land remain unirrigated because water is not available. Clearly,
CLIMATE 11

optimum use of the water resources of the basin cannot be attained 

until both surface-water and ground-water supplies are efficiently 

utilized.

VEGETATION

Water-loving vegetation of generally low economic value is dominant in low-lying parts of the Malad Valley. Phreatic vegetation also 

grows along the banks of many streams, where it serves to maintain 

channel stability. According to Mower and Nace (1957), the prevailing type of phreatophyte is mainly a function of the depth to \vater. 

In general alfalfa (an important cash crop) and rabbitbrush grow 

where the depth to water ranges from 10 to 35 feet; desert saltsrass, 

greasewood, and pickleweed grow where the depth to water is £ to 10 

feet; sedge, wire rush, marsh reedgrass, and desert saltgrass grow 

where the depth to water is 1 to 5 feet; rushes, cattails, and sedges 

grow where depth to water is only a few inches, or where water is 

ponded during most of the growing season. In all, water-loving vegetation occupies nearly 13,000 acres of bottom land, principally south of 

Malad City.

In uncultivated valley areas where the depth to water is beyond the 

reach of water-loving vegetation, sagebrush and native grasses rre the 

most abundant plants. Sagebrush is the dominant plant form on the 

foothills between altitudes of 5,600 and 6,000 feet where it is usually 

associated with juniper. Juniper, scrub oak, and scrub maple arc prevalent from 6,000 to 7,000 feet. Above 7,000 feet, dense stands of pine, 

fir, spruce, and aspen grow wherever the environment is favorable.

CLIMATE 

PRIMARY CONTROLS

The climatic regimen of the upper Malad River basin is governed 

by the same physical elements that control daily weather throughout 

the temperate zone. Differential heating between landmasses and the 

oceans results in the establishment of the semipermanent atmospheric 

centers of high and low pressure. In winter, the extensive land areas 

of the northern hemisphere lose heat to the atmosphere at a faster rate 

than the adjacent oceans. The consequent buildup of cold air over the 

continent creates reservoirs of heavy dense air at the surface. The 

relatively warmer and therefore lighter air over the oceans tends to 

rise, generating centers of low pressure. This process reverses itself in 

summer when landmasses are warmer than ocean areas at the same 

latitude.

The principal centers of weather action affecting the climate of the 

Malad basin in winter are the Aleutian low and the Great Basin high;

367-858 O 70 <3
12 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

in summer the eastern Pacific high is dominant. Each of th°.se pressure 

cells is characterized by seasonal changes in intensity; in addition, the 

Aleutian low and the eastern Pacific high migrate considerably. Seasonal variations in the characteristics of large quasi-permanent pressure systems stem from the changing pattern of land and sea temperatures previously outlined. The Aleutian low and the Great Basin high 

are most intense in winter, whereas the eastern Pacific high, is weakest 

at that time. With the approach of summer the Great Basin high 

dissipates and the Aleutian low weakens considerably. The eastern 

Pacific high, on the other hand, attains its peak intensity in summer 

and dominates the weather of a large part of the West, including southeastern Idaho.

Seasonal variation of air pressure at the surface and global atmospheric movement strongly influence the climate of the Malad River 

basin. Weather systems are transported from west to east by the prevailing westerlies which are the principal element of the general circulation pattern affecting the climate of southeastern Idaho. Although 

mostly well above the friction zone near the earth's surface, the westerlies vary widely in direction and intensity from day to day. Much 

of this variation is due to planetary or long waves in the up ^er westerlies that are now generally recognized as the primary factor controlling 

weather in the middle latitudes. It has also been shown that wave 

trains in the upper air circulation are closely related to the semipermanent pressure centers at sea level (Klein, 1956, p. 203-219). Therefore, the orientation of the planetary waves with respect to the Malad 

Valley plus large-scale centers of weather action at the surface constitute the principal atmospheric controls on weather and climate in the 

study basin.

The Pacific Ocean is the primary source of moisture for much of the 

West owing to the prevailing west-to-east atmospheric circulation. Accordingly, the topographic barriers between the upper Malad River 

basin and the Pacific Ocean have a profound effect on the amount of 

moisture reaching the basin. Because the numerous north-south mountain ranges are oriented orthogonally to the moisture flow from the 

Pacific Ocean, they may be labeled as "moisture barriers." The amount 

of uplift to which a given quantity of air is subjected depends on the 

specific route it is forced to take over the mountains. However, it has 

been shown that Pacific airmasses are uplifted at least 6,000 feet by 

the time they arrive over the Malad River basin (U.S. Department of 

Commerce, 1953, p. 11). Because most of the moisture in the atmosphere is concentrated within 6,000 feet of the surface, much of the 

precipitable water of any maritime airmass will be removed long 

before it reaches the Malad River basin.
CLIMATE 13

10

PRECIPITATION, IN INCHES

FIGURE 5. Variation of average monthly temperature and precipitation at

Malad City.
14 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

TEMPERATURE 

SEASONAL VARIATION'S

Temperatures in the upper Malad River basin have strong continental characteristics as demonstrated by the graph depicting the 

variation of average monthly temperature and precipitation for Malad 

City (fig. 5). The range of mean monthly temperatures at Malad City 

is almost 50 °F.; extreme temperatures range from 25° to 108 °F. 

Temperatures as low as 33°F have been recorded at the Malad City 

Airport. January is the coldest month and July the warmest. December is normally colder than February, which is characteristic of a 

continental-type climate.

The principal factors affecting the temperature regimen of the 

project area are (1) the rugged north-south-trending mountain ranges 

flanking the basin and (2) the geographic location of the area with 

respect to the Pacific Ocean and the Canadian subarctic region. Temperatures in the Malad River basin would be more nearly maritime 

that is, warmer in winter and cooler in summer were it not for the 

mountain ranges between the basin and the Pacific Ocean. Some protection from severe winter weather is afforded by mountainous areas 

east of the basin which frequently deflect Arctic airmasses away from 

the area. The mountains thus tend to isolate meteorologically not 

only the Malad River basin but the entire Great Basin a? well from 

the hemispheric circulation. The resulting atmospheric stagnation 

causes a buildup or increase in air pressure over the area. High pressure, in turn, desiccates the atmosphere and produces an abundance of 

fair weather. Owing to the normally small amount of cloud cover, 

solar-radiation absorption at ground level is high during tH day as is 

the loss of heat due to terrestrial cooling at night. The net effect of 

the prevailing fair weather on temperatures in the basin is to cause 

relatively large fluctuations in daily and seasonal temperatures. For 

example, during the latter part of July at Malad City, maximum 

daily temperatures of 90°F or higher can be expected mrre than 50 

percent of the time (fig. 6). On the other hand, owing to large radiational losses, cool nighttime summer temperatures prevail as demonstrated by the fact that minimum temperatures are lower than 60 °F 

more than 85 percent of the time. Frost may be expected to occur as 

late as June and as early as September. The average length of the 

growing season is 130 days.
DAILY MINIMUM TIME OF PERCENTAGE 

WAS OR EQUALED TEMPERATURE 

SHOWN THAT THAN LOWER 

§

ro w -F* m 

oooo

\

DAILY MAXIMUM TIME OF PERCENTAGE 

OR EQUALED TEMPERATURE 

SHOWN THAT EXCEEDED 
16 HYDROLOGY, TIPPER MALAD RIVER BASIN, IDAHO 

VERTICAL TEMPERATURE GRADIENT

Evapotranspiration, one of the principal elements in any waterbudget analysis, is highly temperature dependent. For evaluation of 

this important variable, some knowledge regarding the rate of change 

of temperature with altitude (lapse rate) is often helpful. An accurate 

assessment of the regional lapse rate was needed to estimate mean 

annual temperature, which was then used to compute wpter loss by 

evapotranspiration throughout the basin. Owing to the scanty 

meteorologic data in the upper Malad River basin, it was necessary 

to use climatic data for all of southeastern Idaho in the lapse-rate 

analysis.

The lapse rate over southeastern Idaho varies seasonally; it is 

greater in summer than in winter. In summer, a high rate of absorbed 

radiation at the surface during the day causes substantial warming of 

the air immediately above the ground. The effect of this hept exchange 

on ambient temperature decreases progressively with incr3asing altitude so that air temperatures near the surface are higher relative to 

those in the midtroposphere and upper troposphere. In winter, on the 

other hand, large outgoing radiational losses at the surface produce 

sharp temperature inversions at night. Accordingly, nighttime temperatures in the valley may be much lower than those observed in the 

mountains. The overall effect is to reduce the average lapse rate in 

winter to about 1°F per 1,000 feet from the maximum seasonal rate 

in summer of about 3.5°F per 1,000 feet.

The mean annual lapse rate in the basin is about 2.5°F per 1,000 

feet, as shown in figure 7, which is based on long-term records of U.S. 

Weather Bureau stations. The lapse rate obtained from figure 7 is 

just 0.2C F lower than that of the standard atmosphere (Landsberg, 

1958, p.161).
CLIMATE 17

10,000

Malad City

Airport \ Malad City 

» ^

Pocatellc

4000

35 40 45 

TEMPERATURE, IN DEGREES FAHRENHEIT

FIGURE 7. Mean annual lapse rate for southeastern Idaho.
18 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO 

HYDROMETEOROLOGY

With the exception of a relatively small amount of surface water 

imported from the Birch Creek basin, virtually all the v^ater in the 

study area is obtained from precipitation. Clearly, any assessment of 

the water potential of the basin must be predicated on a thorough 

analysis of all aspects of precipitation. To accomplish this task, one 

should analyze the causes of rainfall if an insight is to be gained into 

the nature of this critical component of the hydrologic environment.

CIRCULATION PATTERNS FAVORING ABOVE-NOLJCAL 

PRECIPITATION

The amount of moisture available for precipitation over the Malad 

Valley is dependent on the strength of the westerlies over the area. 

The strength of the westerlies, in turn, is a function of the pressure 

gradient within the troposphere. Any orientation of pressure patterns 

that causes a strong movement of air from the Pacific Cbean (especially the southeastern Pacific) toward Idaho is likely to produce 

heavy precipitation.

The upper air regime commonly associated with heavy precipitation 

in Idaho is characterized by a trough of low pressure off the California 

coast with a stronger-than-normal ridge oriented north-south over 

the Rocky Mountains. The southwesterly movement of air associated 

with such a system can move vast quantities of moisture-laden air 

from the southeast Pacific Ocean area inland toward southeastern 

Idaho. For example, in January 1956 a deep trough of low pressure 

off the west coast of North America (fig. 8) produced a steep pressure 

gradient in the eastern Pacific Ocean; concomitantly, a ridge of high 

pressure developed along the Rocky Mountains. This pressure field 

induced a stronger-than-normal flow of air to move over the project 

area from the Pacific Ocean. Moreover, the trajectory of this air was 

from the west-southwest so that much of its path was over warm 

ocean surfaces. The high moisture content of the maritime air, in 

combination with the strong flow pattern, resulted in above-normal 

precipitation in much of the West. Mean monthly precipitation in 

areas adjacent to the upper Malad River basin was above normal, 

ranging from 128 to 260 percent of normal, as shown in the upper 

right-hand part of figure 8. Wave patterns in the upper westerlies 

are most sinuous in the late fall and winter; in summer th°,y are less 

pronounced. The overall effect of the weakened wave pattern in summer is to reduce the ability of moisture-laden airmasses tc penetrate 

very far inland, thereby fostering aridity in much of the West.

Despite weakening of the atmospheric circulation over southeastern 

Idaho in summer, the influx of moisture from the southeastern Pacific
HYDROMETEOROLOGY

2.29 inches McCammon 

164 percent^ 3_Zl' nches

' \ 260 percent /:::: ..4

2.35 inches":: 

165 percent^

 j:::: 2.44 inches^ 

__IDAHO ^U74~percent* _ _

Snowville UTAH 

2.26 inches 

171 percent

Grace

1 53 inches 

[128 percent

[ontpeHer(. 

'1.86 inches 

J 186 percent 

Veston O93lriSrl

155 percent I -r 

3.25 inches \ 1 

179 percent Vy 

 Logan 

2.74 inches 

177 percent

M

JANUARY 1956

3.39 inches 

390 percent)

. Gray I

?.32 inches 

307 percent

2.58 inches i

2.53 percent .

0.82 inches

255 percent (v jtJl±""-"" -^ iirace\ 

::V.V107 percent illinches ' 

.ii{|:::?| 178 P ercent

) £

^^y inc ii'Malad"City l.uy percent 

242 percent!1.:::-:;/ ^ ,-^Lifton 1 

';:;:,1.23 inches^Preston r*\ | 

IDAJHO ^ 246~percent _ _ ___/ /_ __I 

,wvale« UTAH ~ .RichmoTTT") ~1 

1.95 inches 1.74 inches \ ( I

394 percent

1.74 inches \ ) 

238 percent Vj 

 Logan

2.25 inches 

331 percent

AUGUST 1951

FIGURE 8. Left, Average height (meters) of the 700-millibar surface. Tl * shaft 

of each wind-velocity symbol is oriented with the wind direction; each barb 

represents 10 knots, and each half barb represents 5 knots. H and L indicate 

centers of highest and lowest pressure, respectively. Right, Resulting monthly 

precipitation (inches) with departure from normal (percent). Outline of the 

Malad River basin shown by stippled areas. After U.S. Weather Bureau.

367_852 0 7C
20 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

Ocean and, to a lesser extent, from the Gulf of Mexico may occasionally 

result in heavy rainfall. During the warm season a weak upper air 

trough in the midtroposphere normally separates the eastern Pacific 

high from a quasi-stationary high over the South-Central United 

States. Frontal activity is rarely associated with the trough, and its 

intensity is so slight that little movement of air is generated by the 

weak pressure field. Accordingly, high pressure predominates, causing 

fair weather throughout much of the West. However, if the trough 

deepens and moves eastward toward the west coast of the United 

States, a flow of moist air may spread as far as southeast Idaho, and 

sporadic thunderstorm and shower activity is likely to be generated in 

the study area.

The mean pressure field for August 1951 shown in the lower part of 

figure 8 portrays a pattern that is conducive to heavy summer rainfall 

in southeastern Idaho. The deeper-than-normal trough extending 

from Washington southwestward to the Pacific Ocean caused a substantial flow of moist air to move inland. The anomalous pmoimts of 

atmospheric moisture over southeastern Idaho produced rainfall which 

ranged from 107 to 426 percent of normal for the month, 'as shown 

in the lower right-hand part of figure 8.

PEESISTENX3E OF CIECULATION PATTEENS

It is well known that drought or wet periods tend to persist, 

frequently for months or even years. For example, droughts of varying 

intensity have occurred in the upper Malad River basin, notably during 

the 1930's, as illustrated in figure 9. The severity of these droughts is 

demonstrated by the 5-year moving averages which trend downward 

during the early years of each drought period. The 5-ye^r moving 

average of precipitation at Malad City reached a record lew in 1958, 

and the drought of the 1950's appears to be the worst of record. The 

recent drought, which began in 1951, continued into the 1960's and was 

not effectively terminated until the spring of 1963, when iroderate to 

heavy precipitation fell throughout southeastern Idaho. From the 

long-term precipitation record at Pocatello, it is apparent that southeastern Idaho experienced a severe drought in the early 1900's. 

Although the severity of this drought cannot be evaluated, it appears 

to have been comparable to that of the 1930's.

Owing to extensive irrigation in the upper Malad River basin, 

even a severe deficiency of precipitation lasting only a ^ear or so 

would not severely affect agricultural production. Brown (1959, p. 99) 

concluded that if adequate soil moisture is available in J?Q/ptember, 

October, May and June in nonirrigated areas where wheat is raised, 

the chance is excellent for an above-average crop yield. Therefore,

22 HYDROLOGY, UPPER MALAD RIVER BASEST, IDAHO

during a severe drought, it may be possible to have at least an average 

crop yield even in dry-farm areas provided that rainfall is well timed. 

During a protracted dry spell, however, the surface-water supplies 

may become seriously reduced after carryover water from earlier wet 

periods is depleted. Moreover, increased pumping of ground-water 

reserves to counter the effect of drought on crops, in combination with 

sharply lowered recharge, may cause substantial decline? in water 

levels.

COLD-SEASON DROUGHT

One of the most common meteorological situations for drought in 

winter is a strong Great Basin high at the surface with an associated 

ridge aloft. The ridge tends to maintain the surface high which, in 

turn, blocks the passage of migratory low-pressure systems. Moreover, the large-scale sinking of air connected with such a system desiccates the air by lowering the relative humidity. A stronger-thannormal eastern Pacific high also causes drought. The clockwise movement of air around such a high results in northerly components of 

air movement over the area. For example, an unusually intense highpressure system off the California coast in February 1953 (fig. 10) 

induced a northwesterly flow of air over southeastern Idaho. Owing 

to the relatively short over-water trajectory of this air, it contained 

little moisture. Accordingly, precipitation in the area adjacent to 

the Malad River basin was deficient during the month, a^ shown in 

the upper right-hand part of figure 10. Extremes ranged from 18 to 

133 percent of normal, and Malad City reported less than half the 

expected average amount. A somewhat less common situation occurs 

when a meridional flow pattern is established by a strong ridge extending from the southeastern part of the Pacific Ocean northward 

into the Gulf of Alaska. A pattern such as this generates a strong 

northerly flow over much of Idaho, thereby cutting off any possible 

sources of moistilre.

WARM-SEASON DROUGHT

Intensification and the zonal expansion of either the eastern Pacific 

high or the upper-level high over the South-Central United States 

results in large-scale subsidence causing drier weather thr,n is usual 

for the study area. Strong pressure ridges in the midtroposphere, 

either over the Rockies or off the Pacific coast, are also conducive to 

a dry-weather pattern. These ridges can effectively block any penetration of moisture from the Pacific Ocean or the Gulf of Mexico.

The YOO-millibar-pressure distribution in June 1951 (fig. 10) illustrates a combination of upper air factors that are conducive to drought 

in the Malad River basin. A somewhat stronger-than-norrral high in 

the eastern Pacific with a strong ridge extending into the Gulf of
HYDROMETEOROLOGY 23

. , __ . 

r^?.?.%City / rj.65 inches 133 percent 

^i-liiniiii:;^ 46 percent r^Lifton

FEBRUARY 1953

0.28 inches 

30 percent

0.96 inches

63 percent 

I

* 0-72 inches 

43 percent 

0.93 inches!

0.82 inches 

inches To~fpercen t 

Lifton

DAHO _ ^OW_ __ £_ _ _

Snowville0.51 inches 

59 percent

UTAH

i

1

JUNE 1951

t

FIGURE 10. Left, Average height (meters) of the 700-millibar surface. The 

shaft of each wind-velocity symbol is oriented with the wind direction; each 

barb represents 10 knots, and each half barb represents 5 knots. H indicates 

centers of highest pressure. Right, Resulting monthly precipitation (inches) 

with departure from normal (percent). Outline of the Malad River basin 

shown by stippled areas. After U.S. Weather Bureau.
24 HYDROLOGY, UPPER MALAD RIVER BASEST, IDAHO

Alaska effectively shielded much of Idaho from landward movement 

of moist Pacific airmasses. Moreover, the subsidence resulting from the 

high-pressure cell produced cloudless skies for extended periods during the month. Despite above-normal sunshine, temperatures were 

below expected seasonal levels owing to the influx of cool air from the 

Gulf of Alaska.

PRECIPITATION INTENSITY AND DISTRIBUTION

Annual precipitation in Malad City may range from 50 to 150 

percent of the long-term average of 15 inches (fig. 11). Although this 

is a fairly large variation, it is by no means unusual for a semiarid 

region. Wide fluctuations in annual precipitation are common to all 

dry areas of the West, so that knowledge of the average annual precipitation of an area is of little use without some information about 

variability. During shorter periods, such as a season or a month, the 

variability in precipitation is even greater.

The pattern of hourly rainfall varies widely in southeastern Idaho 

throughout the year with regard to both time of occurrence and 

intensity. The number of occurrences of measureable rainfall during 

the day is highest in January and lowest in July at Pocatello (fig. 12), 

the first-order Weather Bureau station nearest to the Malad River 

basin. Precipitation is most likely to occur during the early morning 

in winter and during the afternoon in summer.

Most summer rainfall results from thunderstorm activity that is 

generated by unstable atmospheric conditions due to steep afternoon 

lapse rates. Under such conditions a quantity of rising air cools at a 

rate that is somewhat less than the ambient lapse rate. After rising 

a given distance, the air is warmer than its surroundings and so, being 

lighter, will continue to rise. This unstable atmospheric condition is 

a prerequisite to thunderstorm activity, for it develops tH vertical 

atmospheric movement necessary for cloud formation.

In winter, the usual nighttime temperature inversion fosters the 

development of low-lying stratus cloud formations. Heavy precipitation seldom occurs under these conditions; however, the likelihood of 

some precipitation is increased, and light rain or snow may fall. April 

and October are transition months so that rainfall patterns may be 

characteristic of either winter or summer.

Owing to the numerous moisture barriers between the basin and 

the Pacific Ocean, rainfall intensities in the project area are not excessive. For example, the maximum recorded 24-hour rainfall at Malad 

is about 3 inches (table 1), far below that observed in many areas of 

the United States at the same latitude. Owing principally to the 

greater moisture-carrying capacity of the atmosphere and the favor-
HYDROMETEOROLOGY 25

22

21

20

19

17

~ 16

15

14

13

12

11

10

\

10 20 30 40 50 60 70 80

PERCENTAGE OF YEARS PRECIPITATION EQUALED 

OR EXCEEDED THAT SHOWN

90 100

FIGURE 11. Annual precipitation duration at Malad City, 1915-60.

able conditions for thunderstorms, greatest rainfall intensities are 

generally observed during the warm season, as shown in table 1.

Maximum rainfall intensities which might be expected in the Malad 

basin for selected recurrence intervals are shown in table 2. This table 

indicates that for any particular year there is a 50-50 chance tH.t rainfall intensities will exceed 0.45 inch in 1 hour on at least one occasion. 

Moreover, there is but one chance in 100 that rainfall will exceed 3.1 

inches during a consecutive 24-hour period in any year (U.S. Department of Commerce, 1961.)
26 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

35

I 20

123456789 10 11 12 1234 56789 10 11 12

HOUR ENDING

FIGURE 12. Seasonal distribution of hourly precipitation at Pocatello.
QUANTITATIVE HYDROLOGY 27

TABLE 1. Maximum recorded precipitation intensities for selected time durations 

by month, at Malad City, 1940-62

[Compiled from records of the U.S. Weather Bureau]

Accumulated rainfall, in inches, during 

Month indicated number of hours

12 24

January ............................

February. ..........................

March--.-....---.-...--....-.--....

April...-...----.-...---....-......

May. ...............................

June.-----.--....--.---...-..---....

July................................

August--.--.---.----.--.--.-...-.-.

September. .........................

October _ .........................

November ..........................

December ..........................

....------..-.--.-.-.-- 0.24

......---...-----.---.- .25

........--...--.--...-- .17

-..--..-....--.---..-.- .37

....................... .45

.........-....----...-- .64

........--....-.--..-.- .82

....................... .65

....................... .35

....................... .30

....................... .40

....................... .20

0.32

.30

.30

.39

.54

.71

.82

.86

.68

.37

.62

.34

0.34

.40

.37

.40

.71

.77

.82

1.27

.96

.37

.77

.44

0.42

.69

.60

.55

1.04

.94

.82

1.27

1.49

.55

1.31

.64

0.7f

.7f

.8?

.65

1.44

1.22

1.01

1.35

2.01

.80 i.69

.8C

0.81

.96

1.10

.71

1.75

1.37

1.22

1.35

2.98

1.16

2 11

1.16

TABLE 2. Rainfall intensity for selected frequencies and time durations, in inches,

at Malad City

[Compiled from records of the U.S. Weather Bureau]

Duration (hours) Recurrence intervals (years) 

6 12 24

9

10 

SO.......--.-....-..

100 .

.......... . 0.45

.............. .65

._ . .8

....... .9

.. .... 1.1

.............. 1.2

0.6

.8

1.0

1.2

1.3

1.5

0.75

1.0

1.2

1.4

1.5

1.6

0.9

1.25

1.5

1.6

1.9

2.1

1.2

1.5

1.75

2.0

2.3

2.5

1.4

1.8

2.0

2.5

2.8

3.1

QUANTITATIVE HYDROLOGY

AREA PRECIPITATION

An evaluation of basinwide water yield is one of the principal 

objectives of this report. Water yield is the runoff from a drainage 

basin; it includes streamflow plus ground water that moves through 

the basin as underflow. The first step in estimating water yield is to 

prepare a mean annual precipitation map of the basin. Because there 

are only two weather stations in the basin, stations adjacent to the 

study area were used to define regional precipitation patterns. An 

analysis of climatological records revealed a preponderance of lowaltitude weather stations. Although mean annual precipitation could 

be defined with reasonable assurance for altitudes below 5,000 feet, 

a precipitation map for the higher altitudes could not be prepared 

on the basis of nearby weather stations.

The climatic controls of the Malad River basin are similar to those 

of the northern Wasatch Mountains of north-central Utah and the 

Caribou Range northeast of the basin. Therefore, a statistical analysis

367-852 O 70 5
28 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

that correlates the climatic and physical parameters of these mountains can be assumed to approximate natural conditions in the Malad 

River basin. Records are available from several long-term precipitation 

stations at altitudes ranging from 4,500 to 6,500 feet in the Caribou 

Range and at four stations in the Wasatch Mountains. The stations 

in the Wasatch Mountains span the full range of altitudes in the project 

area. These data and those from four valley stations in or near the basin 

were plotted on a graph relating precipitation to altitude (fig. 13). 

Curves were initially fitted to the Caribou Range (curve A) and 

Wasatch Mountains (curve C) data. A regional precipitation-altitude 

curve for the basin (curve B] was then fitted to the observed data in 

the study basin utilizing the slope control of those previously drawn. 

Curve B is believed to represent reasonably well the ambient precipitation-altitude relations of the upper Malad River basin. In preparing 

the regional precipitation-altitude curve, all station records were made 

comparable by using a common base period (1931-60), thereby 

eliminating inconsistencies that may have arisen from the use of 

records of varying lengths.

9000

8000

7000

6000

5000

4000

Blac

G

Blackfoot, 

Idaho^

Pocatello/

Gray, 

(foot Dam, o 

Idaho

 ace, Idaho'

/o

/ Idahol

'' rA

Malad City 

Airport

daho /Con 

/ Idah

¥_/Preston, 

</ Idaho / 

alad /a'' -ity °/

/^Loga

/

Ja, / 

10 /

/

Richmond, U1 

i, Utah

/

[/

/

ah

/ Mo

/

nte Cristo,J>' 

Utah /

5 10 15 20 25 30 35 4 

MEAN ANNUAL PRECIPITATION, IN INCHES

FIGURE 13. Regional precipitation curves for the Caribou Range (A) ; the 

Malad River basin (B), and the northern Wasatch Mountain? (C).
QUANTITATIVE HYDROLOGY 29

R 34 E

T 105

EXPLANATION

T 11 S

T 12 S

T 135

T 14 S

T 155

T. 165

Line of equal mean 

annual precipitation

Interval 2 and 5 inthes

XFORD 

PEAK

UTAH

5 MILES

FIGUEE 14. Mean annual precipitation in the upper Malad River bisin.
30 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

With the aid of the regional basin curve (curve B, fig. 13), a mean 

annual precipitation map (fig. 14) was made for the project area. 

This figure was prepared by use of an overlay on a topographic map 

of the basin. The altitudes corresponding to selected amounts of precipitation were obtained from the regional basin curve, and their 

smoothed outline was drawn on the overlay sheet.

The range of mean annual precipitation in the basin is about 20 

inches. Precipitation on the highest summits of the basin (about 9,000 

feet) is about 21/2 times greater than that on the Malad Piver flood 

plain above Woodruff. The estimated mean annual precipitation for 

the entire basin is 18.5 inches.

EVAPORATION

The quantity of water evaporated from free-water surfaces in the 

project area may be estimated from land-pan evaporation data at 

nearby stations. The evaporation from free-water surfaces also may 

be applied to waterlogged land surfaces in the basin to estimate the 

annual water losses from such areas.

Records of evaporation from class A land pans at nearby stations 

(table 3) show that evaporation in the basin is greatest in July. A 

quantitative evaluation of evaporation from free-water surfaces and 

waterlogged areas in the Malad River basin can be obtained from 

these data because their adjusted average provides a fair estimate 

of water loss from areas of high evaporative opporturity. Upon 

applying the standard adjustment coefficient (0.7) to land-pan values, 

the loss from lakes, reservoirs, and waterlogged areas is estimated 

to be nearly 7 inches during July. Direct measurement of evaporation 

is not possible during the cold season owing to ice formation in land 

pans.

TABLE 3. Mean monthly land-pan evaporation, in inches, from selected stations

[Figures in parentheses indicate length of record, in years; e, estimated. Compiled from records of the U.S.

Weather Bureau]

Station Apr. May June July Aug. Sept. Oct.

Aberdeen, Idaho. ...............

Lifton, Idaho.................. _ .....

Palisades, Idaho....... ...... . . ....

Bear River Refuge, Utah..............

Logan, Utah..... __ ...... _ .......

Mean of five stations... _ .........

............ 4.27

(2) 

............ 4.10

(11) 

............ e3.6

............ 5.05

(9) 

............ 4.29

(7)

............ 4.3

7.10

(22) 

6.33

(25) 

5.48

(8)

7.70

(16) 

6.18

(10)

6.6

8.01

(24) 

7.62

(25) 

6.20

(8)

9.31

(21) 

7.43

(10)

7.7

9.30

(24) 

9.20

(25) 

8.03

(10)

11.39

(22) 

8.91

(10)

9.4

8.47

(24> 

8.27

(25) 

7.23

(9)

10.12

(24) 

8.08

(10)

8.4

5.65

(23) 

5.74

(25) 

5.40

(12)

6.71

(24) 

5.49

(11)

5.8

3.54

(14) 

3.19

(24) 

3.28

(5)

3.60

(15) 

3.27

(10)

3.4
QUANTITATIVE HYDROLOGY 31

To estimate the loss from November through March, use was made 

of a formula developed by Meyer (1944, p. 238) as follows:

where

£T =mean monthly evaporation, in inches

e s = saturation vapor pressure of water corresponding to

mean monthly temperature, in indies 

ea= actual air vapor pressure for the month, in inches 

/y = mean monthly wind velocity, in miles per hour

From this equation the following values for evaporation, in inches, 

were obtained : November, 2.3 ; December, 1.1 ; January, 0.9 ; February, 

1.1, and March, 2.4. Mean annual land-pan evaporation in the Malad 

Valley is computed to be 53.4 inches. Applying a 0.7 adjustment coefficient to land-pan values, the computed average annual evaporation 

from lakes and waterlogged areas is about 38 inches.

EVAPOTBANSPIBATION

Evapotranspiration is water that is returned to the atmosphere 

from a land area by direct evaporation from water surfaces and moist 

soil and through transpiration by vegetation. Evapotranspiration 

has first call on precipitation; it reduces the amount of water available for streamflow or for recharge to the ground-water reservoir. 

It may be considered "nature's take," or that part of precipitation 

that is consumed by plants, economic or not, and otherwise lost directly back to the atmosphere. The rate of evapotranspiration depends 

chiefly upon air and water temperatures, wind movement, solar radiation, humidity, availability of moisture, and character of the land 

surface and plant cover. Many of the climatic parameters a Meeting 

evapotranspiration are so interrelated that it is virtually impossible 

to isolate them. In addition to climatic factors, numerous othQ,r variables such as plant cover, land management, degree of urbanization, 

and type of soil affect the rate of water loss. Because the interrelation 

of these variables is complex, direct field measurement of evapotranspiration is difficult and subject to large errors.
32 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

WATER YIELD

If direct measurement of evapotranspiration were possible, computation of water yield would be simple. Evapotranspiration may, however, be estimated by any one of several indirect methods. Using the 

water-balance equation we may compute water yield as follows:

Water yield=precipitation evapotranspiration ± change 

in ground-water storage.

If a long period is selected for analysis, the change in ground-water 

storage can be neglected, and mean annual water yield (comprising 

both ground water and surface-water runoff) is the difference between 

precipitation and evapotranspiration. Unfortunately, su°li an approach is generally not feasible and other methods must be applied.

Except in areas where the land surface is sufficiently close to the 

water table to be continuously saturated, the actual rate of evapotranspiration from a given area at any particular time may rarge from a 

maximum equivalent to that in saturated soils immediately rfter heavy 

precipitation to none during protracted dry periods. Clearly, water 

loss is largely a function of "evaporation opportunity," or the percentage of time that soils are saturated. In the semiarid Malad Valley, 

such conditions occur only in permanently waterlogged areas and 

where fine-grained clayey soil inhibits downward percolation of water. 

Because of numerous unassessable factors, accurate computation of 

monthly evapotranspiration rates for the basin as a whole if practically impossible with present-day techniques. Nevertheless, rough estimates of water losses from irrigated areas can be obtained b^ applying 

Thornthwaite's method (1948).

Thornthwaite used mean monthly air temperature and a correction 

factor based on hours of daylight to compute potential evapctranspiration. This is the amount of water that might be lost in an irrigated area 

that is adequately supplied with water. Using a nomogram devised by 

Van Hylckama (1959, p. 107) to simplify computations, the potential 

evapotranspiration for the Malad Valley is estimated to be 24 inches 

annually. Thus, a water loss of about 2 feet may be expected from row 

crops such as sugar beets where ample irrigation water is applied. The 

water losses from water-loving plants, such as alfalfa, are greater 

than those resulting from row crops and may approach or even exceed 

evaporation from free-water surfaces.

The determination of water yield is based on a method developed by 

W. B. Langbein for use in the Baft River basin of south-central Idaho 

(Nace and others, 1961, p. 36-47). A graphical correlation was plotted 

between the ratios of runoff to potential evapotranspiration (R:L] 

and of precipitation to potential evapotranspiration (P :L) for selected 

river basins throughout the United States (fig. 15). T1V gaging
QUANTITATIVE HYDROLOGY 33

in 5;

-H a

NOIlVaidSNVaiOdVA3 -|VllN310d 01 CH3IA d31VM JO OllVd
34 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

stations used by Langbein and others (1949, table 4) were those for 

which the measured outflow is the total water yield of trs basin. In 

most instances, the selected gaging site is underlain by impermeable 

deposits that block the movement of ground water, thereby forcing it 

to move out of the ground and into the stream above the station. Thus, 

the entire water yield passes the gaging station as streamflow. Potential evapotranspiration is computed from a graph relating water loss 

to mean annual temperature based on precipitation-runof* studies in 

humid areas (Williams and others, 1940, p. 53). In computing mean 

annual temperature for his analysis, Langbein attempted to allow for 

seasonal variations in evaporation rates by weighting mean monthly 

temperatures by the amount of precipitation in each month. For example, if summer were the wettest time of the year, then tH weighted 

annual temperature and therefore the computed potential evaporation 

would be higher than if heaviest precipitation fell in winter. In the 

Malad River basin precipitation is fairly well distributed throughout 

the year so that only a small adjustment had to be applied to mean 

annual temperatures.

The individual basin data in figure 15 are in fairly good agreement 

with the curve of relation although some scatter is evident. The scatter, of course, is to be expected because factors other than climate can 

have a significant effect on water loss. Water loss in a basin containing 

highly permeable soils is generally lower than expected because water 

percolates downward rapidly and thus reduces the chance of loss due 

to evaporation. By way of illustration, evapotranspiration in the southcentral part of Long Island, N. Y., is estimated to be about 21 inches, or 

only about 46 percent of the mean annual precipitation (Pluhowski 

and Kantrowitz, 1964, p. 30). The average ratio of evapotranspiration 

to mean annual precipitation for the Nation as a whole is about 70 percent. The low ratio of evapotranspiration to precipitation on Long 

Island is ascribed- to the highly permeable sandy soils underlying the 

area which limit evapotranspiration and permit high recharge rates to 

the ground-water reservoir. Clayey soils, on the other hand, tend to 

inhibit the infiltration and percolation of precipitation, thereby increasing the opportunity for large evapotranspiration losses. Other 

factors such as soil depth, runoff of snowmelt from frozen ground, 

vegetative cover, degree of urbanization, and topographic relief also 

have a significant bearing on producing the scatter of the data points in 

figure 15.

To test the validity of Langbein's data with regard to southeastern 

Idaho, a study was made to find gaging stations near the project basin 

so situated geologically that ground-water outflow past the stations is 

negligible and surface runoff is equivalent to water yield. Two suitable
QUANTITATIVE HYDROLOGY 35

stations were found, "Willow Creek near Eirie, Idaho, and the Portneuf 

River at Topaz Station, Idaho. The areas drained by both stations are 

topographically and climatically similar to the project area, so that 

statistical inferences about their hydrologic characteristics can be 

extended to the upper Malad River basin. Results of analyses of data 

for the basins above these gaging sites are as follows:

Gaging station

Average

altitude

(feet)

_..... 6,380

...... 6,020

Mean

annual

temperature (° F)

(weighted)

38.1°

39.6°

Basin

precipitation

(P)

(inches)

18.0

19.2

Potential

evapotranspiration (L)

(inches)

16.8

17.5

Runoff

(R)

(inches)

4. 7

4.6

Close agreement is obtained when the P: L and R: L ratios for these 

stations are plotted in figure 15. Evidently, the general relations defined in figure 15 are applicable to southeastern Idaho and can be used 

to estimate water yield in the upper Malad River basin. This was done 

by estimating the mean annual temperatures for the range of altitudes 

in the basin. An adjustment of 2°F was applied to determine the 

weighted mean annual temperature in accordance with Langbein's 

procedure. From this the variation of mean annual evapotranspiration 

loss (L) in the basin was computed using the Williams plot (Williams 

and others, 1940, fig. 5). Mean annual precipitation was obtained from 

the regional basin curve (fig. 14) from which the P:L ratio was determined. By positioning the P: L ratio on the curve in figure 15, the 

R:L ratio was obtained; from this, R was computed. The computed 

R value represents the mean annual water yield along a specific altitude contour.

A water-yield map for the Malad River basin was drawn (fig. 16) 

in accordance with the above procedure. Water yield in the basin 

ranges from 0.8 inch to 19 inches and averages 4.0 inches from the 

entire basin. The importance of the mountains to the water resources 

of the project area is obvious from an examination of this figure. 

Water yields from the higher parts of the basin are eight to 20 times 

those from low-lying areas. The water yields shown in figure 16 apply 

to water yields at points of generation. Anomalous losses of water 

due to phreatic vegetation or irrigation are not accounted for in this 

graphical relation. Although runoff is estimated to be about 4 inches, 

something less than this amount of streamflow actually flows past 

Woodruff at the lower end of the basin. This difference is an indirect 

measure of the subsurface outflow from the Malad River basin above 

the Woodruff gaging station.

The mean water yield from and precipitation on various zones and 

subbasins of the study area are portrayed in figure 17. Subbasin 1
36 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

T 10 S

EXPLANATION

T 11 S

T 12S

T 13 S

T 15S

T 16 S

FIGURE 16. Mean annual water yield.
QUANTITATIVE HYDROLOGY 37

/; 0.0 .Slg *ll

<

EXPLANATION 

30

112-30') 

1 H roNEIDA CO V I

i; \

4 2° 00

SMILES

FIGURE 17. Regional distribution of precipitation and water yield in the 

upper Malad River basin and in the upper Birch Creek basin (stippled).
38 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

represents the Little Malad Eiver drainage area above Elkhorn Reservoir (Dam) ; subbasin 2, Birch Creek above transbasin diversion; 

subbasin 3, Devil Creek above Campbell Creek; and subbasin 4, Deep 

Creek above Henderson Reservoir. Although Birch Creek is just outside the upper Malad River basin, it has been included in the analyses 

because most of its flow is diverted into the study area. Mean annual 

precipitation ranges from a low of 16.0 to a high of 25.4 inches, and 

annual water yield ranges from 2.4 to 10.4 inches in zone 5 and subbasin 2, respectively. A 60-percent increase in precipitation between 

these two subareas resulted in nearly a 450-percent increase in water 

yield.

GROUND WATER

GEOLOGY IN RELATION TO GROUND WATER

The mountains of the study basin are composed principally of 

Paleozoic rocks (fig. 18) ranging in age from Cambrian to Permian 

(Mower and Nace, 1957). Extensive limestone deposits crop out along 

the Blue Spring Hills in the Wells stratigraphic unit (Piper, 1924). 

Hadley (1963) reported that the Blue Spring Hills are a series of 

fault blocks that have been tilted to the southwest. Much of the northern part of the basin in underlain by the Monroe Canyon and Madison 

Limestones. The Salt Lake Formation consisting of continental sandstone, shale, and siltstone is extensively exposed along the flanks of 

the Malad and Bannock Ranges northeast of Malad City.

The Bonneville and Provo shorelines of ancient Lake Bonneville 

are well defined on foothills surrounding the Malad Valley. A thick 

sequence of sediments accumulated beneath the lake (the Lake Bonneville Group) in Quaternary time. This sequence consists of layers, 

lenses, and tongues of permeable sand and gravel interbedded with 

less permeable to impermeable beds of silt and clay. The Lake Bonneville sediments are underlain by sediments of similar characteristics 

that were deposited by older Quaternary lakes. The aggregate thickness of the Lake Bonneville Group is not known, but probably does 

not exceed 50 feet at the deepest points near the middle of the Malad 

Valley (R. W. Mower, written commun., 1967). Wells exceeding 700 

feet in depth do not reach bedrock.

In addition to the lacustrine deposits, alluvial and colluvial deposits 

accumulated during dry climatic regimes. During dry periods the 

lake receded beyond the lower boundary of the Malad Vr!ley, and 

fluvial erosion and deposition took place. Both fine- and coarse-grained 

materials were deposited by streams as they gradually swung laterally 

across the valley. Fine-grained materials were washed onto the valley 

floor from the surrounding uplands by such erosional processes as 

sheet runoff, soil creep, and gullying. The resulting heterogeneous
GROUND WATER 39

deposit, now hundreds of feet thick, forms the ground-water reservoir. 

This unconsolidated highly porous geologic unit of widely varying 

permeability is analogous to a sponge, absorbing much of th°, runoff 

from the mountains. In this way, the ground-water reservoir partially 

deters the rapid outflow of water from the area and substantially 

reduces natural water losses by minimizing the opportunity for 

evapotranspiration. The ground-water reservoir thereby fulfills the 

vital function of conserving and storing water for man's use.

THE GROUND-WATER RESERVOIR

The source of much of the economically recoverable ground water 

in the project area is the thick sequence of unconsolidated alluvial 

deposits of gravel, sand, silt, and clay underlying the Malad Vrlley and 

its principal tributary valleys (fig. 18). The gravel and sand beds 

are of small areal extent, and clay and silt are the dominant materials. 

A cross section along line A-A' of figure 24 shows the general nature 

of the deposits in the area west of Malad City (fig. 19). Gravel or 

sand and gravel alternate irregularly with clay, silt, or clay with 

gravel; the former are aquifers, strata producing water, and the latter 

are aquicludes, strata that yield little or no water. The individual 

beds, such as the sand and gravel at and near the 4,500-foot level in 

the plotted logs, are not necessarily correlative. Many individual 

deposits thicken, thin, or pinch out entirely over «, few tens or Kindreds 

of feet. Water is found in the pore spaces between particles composing 

the ground-water reservoir. Although fine-grained material such as 

silt and clay are highly porous, they offer considerable resistance to 

the movement of water and are very low in permeability. Sand and 

gravel, on the other hand, are permeable because of their relatively 

low frictional resistance to water movement.

Ground water occurs under unconfined conditions in the middle 

and upper parts of the Malad Valley and in the alluvium of most tributary valleys. Perched water occurs locally in much of this ar^a in the 

lenses of sand and gravel that are separated from the main water 

table by less permeable material. Artesian ground water occurs at 

depths ranging from a few tens of feet to more than 70 feet south of 

Malad City, where many wells tap aquifers in the Lake Bonneville 

Group of Pleistocene age. The Woodruff fault (fig. 18), which trends 

east-west across the constricted south end of the Malad Valley, is 'a 

major factor governing flow patterns within the upstream groundwater reservoir. The upthrown southern block of impermeable Paleozoic sedimentary rocks effectively blocks the downvalley movement 

of ground water (Nace and Mower, 1957, p. 8). Some of the deeper 

water-bearing sediments in the Malad Valley probably abut against
40 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

R. 34 E

T 105

T. 11 S

T. 165

Geology compiled by E. J. Pluhowski. 

chiefly from Hadley (1963, pi.29) and 

Nace (unpublished field notis).

SMILES

FIGURE 18. Generalized geologic map of the upper Malad River basin.
GROUND WATER 41

the fault block creating artesian conditions in parts of the groundwater reservoir. Considerable upward migration of artesian water 

takes place through uncased or leaky artesian wells, especially in areas 

just north of the Woodruff fault and south of a line between Pleasantview and Malad City.

RECHARGE

The bulk of the recharge to the ground-water reservoir is from 

direct infiltration of precipitation or surface runoff into the alluvial 

fans ringing the Malad Valley, from losing streams and canals, and

EXPLANATION

Alluvial deposits

Interbedded clay, silt, sand, 

andgravel, mainly in flood 

plains and fans. Locally 

contain unconfined ground 

water

Lake sediments

Mostly clay with very flat 

surfaces, locally with 

high salt content: contain 

artesian water

A QTsv A

Silicic volcanic rocks associated 

with the Snake River Group

Welded tuffs and latite; ash, silt, sand, 

and gravel flows. Yield moderate 

amount of water to stock wells

Salt Lake Formation

Continental sandstone, shale, and siltstone. 

Yields small amounts of water to stock 

wells

Rocks undifferentiated

Interbedded limestone, quartzite, sandstone, 

argillaceous shale, and gray dolomite. 

Not a good aquifer except locally where 

fractured

D 

U

Woodruff fault

U,' upthrown side 

D; downthrown side

t <

It 

V 5

a

Contact

Basin boundary

A______A'

Trace of section shown 

in fig. 19

FIGURE 18. Continued.
EXPLANATION

Clay or clay 

with gravel

Gravel or sand 

and gravel

FIGURE 19. Generalized logs of selected wells along line A-A' of figure 24. D

Datum is sea level. Vertical scale greatly exa
GROUND WATER 43

from unconsumecl irrigation water. Some recharge is received from 

precipitation that falls on the floor of the Malad Valley and infiltrates 

downward through the soil zone and the unsaturated zone. However, 

much of this water is retained as soil moisture and only a small amount 

reaches the ground-water reservoir. A small quantity of recharge 

reaches the Malad Valley aquifer system as a consequence of transbasin diversions of surface water from Birch Creek. The imported 

water is used for irrigation north of Malad City, and part of it niters 

downward into the ground-water body.

The alluvial fans surrounding the floor of the Malad Valley are 

the principal zones of recharge for the underlying aquifer system. 

The heterogeneous mixture of clay, silt, sand, and gravel composing 

the alluvial fans laps directly against rocks of Paleozoic age that form 

the surrounding mountain ranges. Two samples of alluvium were 

obtained to illustrate in a cursory manner their textural characteristics 

(fig. 20). Sample 1 is from soil at the base of the exposed alluvium 

near the western edge of the Malad Valley floor, and sample L is from 

the upper part of the exposed alluvium southeast of the village of 

Cherry Creek. The relatively coarse material composing srmple 2, 

obtained at a point about 500 feet above the valley floor, is in sharp 

contrast to the predominantly fine-grained material in sample 1. Much 

of the material near the base of the exposure is very fine sand, silt, and 

clay, whereas farther upslope coarse sand and gravel predominate. 

Owing to the highly permeable zone in the upper part of the alluvial 

fans, runoff from mountain streams and precipitation directly on the 

alluvium is readily absorbed and transmitted to the ground-water 

reservoir.

0.5 1.0 2 5 

PARTICLE SIZE, IN MILLIMETERS

FIGUEE 20. Particlensize distribution of selected soil samples in the Malad Valley.

367-852 O 70 7
44 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

111 the northern part of the Malad Valley where water-tab]e conditions prevail, recharge is derived principally from the losir? stream 

channels, irrigation water seepage, and direct infiltration of precipitation. The artesian aquifiers are recharged directly by precipitation 

where they crop out around the borders of the Malad Valley or by 

lateral downbasin movement of ground water. They may also be 

recharged locally by water from water-table aquifiers where pressure 

heads decrease with depth.

Water-level fluctuations in wells indicate changes in storage resulting from recharge to or discharge from the ground-water reservoir. 

When recharge exceeds discharge, water levels rise; conversely, when 

recharge is less than discharge, water levels decline. Figure 21 shows 

how three wells with long-term records have responded to changes in 

the overall water balance of the ground-water reservoir. In most years, 

two water-level observations were made one in the spring- and the 

other in the fall. In general these measurements show that water levels 

are highest in April or May and lowest in October or November. Overall a fairly stable condition existed from the start of records in 1943 to 

1954; that is, aside from seasonal fluctuations in water levels, no 

overriding upward or downward trend is discernible. From late 1954 

through the early 1960's, water levels have trended downward. Two 

factors may have contributed to the observed decline in water levels: 

(1) a drought which began in 1952 and (2) increasing withdrawals 

from the ground-water reservoir through irrigation wells. Since 1963, 

water levels have stabilized at a new equilibrium position which is 

significantly lower than that recorded prior to 1955.

MOVEMENT

Upon reaching the water table by downward percolatic n, water 

moves in directions and at rates governed by head differences and 

hydraulic characteristics of the aquifer system. Ground water moves 

from areas of higher hydrostatic head to areas of lower head in the 

direction of the steepest hydraulic gradient. Hydraulic gradients and 

the permeability and porosity of the aquifer system determine the 

rate of ground-water movement.

It is not possible, at this time, to give a detailed description of 

the movement of ground water in all areas of the study basin. The 

horizontal component of ground-water flow generally follows the 

trend of the principal tributary valleys. Thus, the dominant direction 

is southward in Little Malad and Devil Creek valleys and predominantly westward in the Deep Creek basin. Along the periphery of the 

Malad Valley, gross direction of movement is toward the center of 

the valley and thence southward toward the constricted kwer end 

of the valley. Ground-water outflow (underflow) from the ^project
GROUND WATER 45

area is southward paralleling the movement of the Malad River 

(fig. 3).

The vertical component of ground-water movement is predominantly downward in all recharge areas, particularly where the artesian 

aquifers crop out near the uplands flanking the Malad Valley. There 

may be considerable migration of water along bedding planes and 

some around well casings. A large -amount of upward migration of 

water occurs near wells penetrating the artesian aquifers. Thermal 

springs in the vicinity of the Woodruff fault suggests the existence 

of upward movement of ground water deep within the reservoir for 

some distance north of the fault. Downstream from the fault to the 

lower boundary of the project area, ground water probably moves 

horizontally with a slight upward component locally.

DISCHARGE

Ground water is discharged from the basin by seepage to streams, 

evapotranspiration, springs, underflow, and pumping. The rate at 

which it is discharged depends on many interrelated factors including season of the year, volume of recharge, intensity of pumping, 

soil and aquifer characteristics, and vegetal cover. Ground-water 

discharge to the Malad River, to springs, and as underflow is at a 

maximum from March to May; it is at a minimum from September 

to November. Evapotranspiration and pumpage are greatest in summer and least in winter.

In contrast to virtually all stream reaches in the Malad Valley, 

the Malad River between Cherry Creek Lane and the Woodruff gaging 

station is a gaining reach. For example, the discharge of the river 

on August 1, 1962, at Cherry Creek Lane was 0.80 cfs (cubic feet per 

second), whereas it was 17.0 cfs at the Woodruff gage at out 4% 

miles downstream. These measurements represent dry-weatl Q,r flow 

so that they reflect ground-water discharge to the reach. O^ing to 

seepage losses upstream and substantial diversions for irrigation, 

summer flow in the Malad River is often very small at the Cherry 

Creek Lane site. Much of the gain in flow below Cherry Cre^vk Lane 

enters the river from Woodruff Springs located 2 miles above the 

Malad River gaging station and about 1 mile south of the Woodruff 

fault. As previously noted, the fault acts as a barrier to ground-water 

movement. The springs and seeps in the reach of the Malad River 

between Cherry Creek Lane and the gaging station discharge highly 

mineralized ground water. The close proximity of Woodruff Springs 

to the Woodruff fault suggests that the springs may derive part of 

their discharge from an upward flow pattern within the ground-water 

reservoir created by the fault.
W

WATER LEVEL, IN FEET ABOVE OR BELOW 

+ + I I I 

r\3 co oo ro *" 

o o o o o 
GROUND WATER 47

In addition to the gaining flow conditions on the Malad Piver in 

the reach above the Woodruff gage, ground-water discharge also enters some of its principal tributaries. Figure 22 shows the pattern 

of flow in the Little Malad River during a period of (1) low base 

flow on August 10, 1966, and (2) medium base flow on December 11, 

1946; site locations are discribed in table <±. The sharp increase in 

flow between sites A and B is due to incoming ground water. DownSTREAMFLOW MEASUREMENT SITES 

BCD E F

10

LITTLE 

Aug. 10

1 MALA 

1966

P

i

1 D

i

1 |ll 

RIVER LOW BASE FLOW

J

||

1 1 : .

« |

Adjusted for 

diversions

/

'1 I

O 

o

LJJ

OT 

tr 15

LJJ 

Q.

LJJ

£ 10

0

m

D 

0 5

z

°> n

i

LITTLE 

MALAD RIVER

MEDIUM BASE 

FLOW

Dec. 11, 1946

l

i

6

'm

1

1

1

'?S$

1

1

~~~" r

?---.-

[

' >. ;

"-

1

1

i511

sm

4

>st

i

-Adjusted for 

/ diversions i "¥5 

|

1 ]:

ill

t o 2 4 6 8 10 12 14 

APPROXIMATE DISTANCE BELOW SOURCE, IN MILES

16

OT 8

DEEP CREEK 

Aug. 11, 1966

0123456 7 

APPROXIMATE DISTANCE BELOW HENDERSON RESERVOIR, IN MILF.S

FIGURE 22. Variation of streamflow along the Little Malad 

River and Deep Creek. Streamflow measurement sites are 

shown in table 4.
48 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

stream from site B (gaging station) streamflow declined slightly, 

indicating seepage loss. The seepage run on December 11, 1946, shows 

the same pattern except that gaining conditions extended somewhat 

further downstream. Along Deep Creek a steady outflow of ground 

water is apparent in the downstream direction. This condition probably is characteristic of the stream, because a protracted drought had 

reduced ground-water levels sharply prior to the seepage run. Despite the substantial loss of recharge, ground-water levels in the Deep 

Creek valley remained higher than stream stages and the result was 

a continued outflow of water from the aquifer to the creek. The bulk 

of the water supply for Malad City is derived from a series of infiltration galleries that intercept the flow of ground water before it 

reaches Deep Creek in the vicinity of site J (fig. 22 and table 4). The 

intercepted water is conveyed to a detention reservoir from which it 

is pumped to the city for distribution.

TABLE 4. Streamflow measurement sites along the Little Malad River and Deep Creek

IdentifiStatlon name cation 

letter in 

fig. 24

Little Malad Eiver above ELkhorn Eeser- B 

voir (Dam). 

Little Malad Eiver below Elkhorn Beservoir (Dam).....----.....--..--..........- C

Little Malad Eiver at Jones Eanch . ........ D

Little Malad Eiver above Sand Eid?e ditch. E 

Little Malad Eiver below St. Johns Canal.. F 

Little Malad Eiver at Sand Eidge damsite.. G

Deep Creek below Henderson Eeservoir. . . . H 

Deep Creek above Malad City water-supply

Distance in 

miles i Quarter

1. 9 SWJiNWJi 

3.6 SEMSEM

i. 3 NW&SWJ!

10.4 NEkNEjJ 

12. 5 NEJaSEJ<£ 

15.0 NE>|SE^

0 NWJiNEJi

2. 9 NWJiSE^ 

4.3 SWjiNEJ^ 

6. 1 SWMSW&

Location

Section

26 

35

7 

17 

33 

3 

14

18

2 

10 

15

T^ownst ip (S.)

12

12

13 

13 

13 

14 

14

14

14 

14 

14

Eange 

(E.)

34 

34

35 

35 

35 

35 

35

37

36 

36 

36

i Distances given are below the source for the Little Malad Biver and below Henderson Eeservoir for 

Deep Creek.

Widespread salinization of soils is evident in the lower Malad Valley 

because of evapotranspiration from the ground-water reservoir. Water 

is withdrawn by direct evaporation if the capillary fringe is at or near 

land surface. The height to which capillary water rises depends 

largely upon the spacing between individual particles. The fire-grained 

material throughout the Malad Valley permits water to rise well above 

the wrater table by capillary action; if this water reaches near the land 

surface, it is subject to evaporation. The rate at which ground water 

is lost to the atmosphere is governed by the same climatic factors that 

affect evaporation from free-water surfaces. Water is also withdrawn 

from the ground-water reservoir wherever plant roots penetrate the 

water table or the capillary zone. Salts in the evaporated water that 

are left behind in the soil zone at or near land surface tend to accumu-
GROUND WATER 49

late there as the evaporated water is replaced by upward moving capillary water. The salts cannot move downward against the rising water 

and no leaching by infiltrating precipitation is possible. Concentration 

of certain salts causes a reduction in soil permeability and hardening 

of the soil. Crops cannot be grown economically under these conditions, 

and the land eventually becomes unproductive.

Some loss of productive land may be due to the increased use of 

irrigation water. However, most of the unproductive acreage in the 

project area consists of saline and alkaline soils resulting from groundwater evapotranspiration, principally in the lower Malad Valley. In 

other words, owing to the natural salinization of soils stemming from 

ground-water evapotranspiration, some sections of the lower Malad 

Valley were unsuited to agriculture long before the advent of 

civilization.

UNDERFLOW

Ground-water outflow^ (underflow) from the upper Malad Biver 

basin in the vicinity of the Woodruff gaging station can be estimated 

by use of the following water-balance equation for the bas'n:

Input=output ± change in storage (1)

where, for the purposes of this study, change in storage may be neglected owing to the long period of record (1931-60) used in the 

analysis.

A small amount of surface water is imported into the study area 

from Birch Creek by way of a transbasin diversion channel. Aside 

from this flow, there is no evidence of any other importatior of water 

from outside the basin. Precipitation in its various forms is clearly 

the basin's major source of water. Inflow to the basin, therefore, consists oi precipitation plus the relatively small quantity imported from 

Birch Creek. Outflow from the basin consists of evapotranspiration, 

surface-water outflow at Woodruff, and underflow. Substituting these 

factors in equation 1 and neglecting storage change over the long term, 

the equation is:

Precipitation+imported water

= evapotranspiration + surface-water outflow + underflow

(2)

Solving for underflow and transposing terms:

Underflow = precipitation evapotranspiration

 surface-water outflow + imported water

(3)
50 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

The first two terms on the right-hand side of equation 3 are equivalent to water yield, or water that is available as surface runoff or 

ground-water recharge after evapotranspiration demands have been 

satisfied. A fair estimate of water yield may be obtained using Langbein's method; however, his ratio plot (fig. 15) is based largely on 

areas that are free of excessive losses due to irrigation. Irrigation is 

widespread in the Malad Valley, so the substantial water looses stemming from irrigation must be included in the water-balance equation. 

Equation 3 can therefore be restated as follows:

U=WY-IL-SWO+IW (4) 

where U=underflow 

WY=water yield

IL = net loss due to irrigation 

SWO = surface-water outflow

IW= imported water (from Birch Creek)

Each of the items on the right-hand side of equation 4 can be quantitatively evaluated so that it is possible to obtain a fair estimate of 

ground-water underflow.

According to a Department of Agriculture census, about 22,000 

acres was irrigated in the Malad Valley in 1959. If potential evapotranspiration is assumed to approximate irrigation-water looses, then 

an estimate of such losses can be made. Potential evapotranspiration in 

the Malad Valley is about 24 inches as computed by the Thornthwaite 

(1948) method. Therefore about 44,000 acre-feet of water was consumptively used in 1959 for irrigation in the basin, but this is not 

the actual water loss due to irrigation. The actual loss from the irrigated lands is that amount remaining after "effective" precipitation 

during the growing season is subtracted from the water loss originating from irrigation (44,000 acre-feet). Effective precipitation is rainfall that infiltrates into the soil and becomes available to crc^s in the 

form of soil moisture. Total rainfall during the growing season 

(May 15-Sept. 30) is 4.6 inches, of which only 2 inches is estimated to be 

available to crops. Accordingly, the loss of water due to irrigation is 

24 inches minus 2 inches, or 22 inches (40,000 acre-feet) annually.

The annual water yield of the basin is 4 inches, or about 115,000 

acre-feet for the 485 square-mile basin above the Woodruff gaging 

station. On the basis of two discharge measurements and tH record 

of flow at Devil Creek above Campbell Creek, transbasin imports of 

flow from Birch Creek are estimated to average 4,000 acre-feet annually. Surface-water outflow from the basin consists of an average 

annual discharge in the Malad River of 61 cfs (44,000 acre-feet) and 

an estimated flow of 7,000 acre-feet in the Warm Springs Canal which 

bypasses the Woodruff gaging station; therefore, the total annual
SURFACE WATER 51

surface-water outflow is about 51,000 acre-feet. Each factor in the 

right-hand side of equation 4 has now been quantitatively evaluated. 

Substituting- the computed values in equation 4 gives:

Underflow=115,000 - 40,000 - 51,000+4,000=28,000 acre-feet

The total outflow^ (water yield) from the upper Malad River basin, 

above Woodruff, is 51,000 acre-feet of surface water plus 28,000 acrefeet of ground water, or about 79,000 acre-feet. For the basin, Mower 

and Nace (1957) estimated that about 37,000 acre-feet of water is 

consumed annually by phreatic vegetation. Clearly, a substantial part 

of the total water resources of the basin is being consumed by waterloving vegetation. Control or eradication of the undesirable phreatic 

growths or replacement with beneficial crops represents a major area 

for improvement in the basin's water balance. A substantial reduction 

in water loss could be gained by careful application of water to irrigated crops so that only water actually needed for optimum growth 

and soil flushing is provided. Elimination of water losses due to 

phreatic growths plus reduction of irrigation losses by optimal application of water to crops could conceivably result in a 50-percent 

increase in the beneficial water use of the basin.

SURFACE WATER

The earliest measurements of streamflow in the upper Malad River 

basin were probably those made during the period 1911-13 on the Little 

Malad River. The first systematic attempt to measure streamflow in the 

basin was made during the 1932 water year (a 12-month period beginning Oct. 1 and ending the following Sept. 30) with the establishment 

of water-stage recorders on six streams. Since that time, about 150 

station-years of record (through 1967) have been collected and about 

half of this represents the combined records of three stations namely, 

Malad River at Woodruff, Little Malad River above Elkhorn Reservoir (Dam), and Devil Creek above Campbell Creek. During the 

1930's, stream-gaging activities were concentrated on Deep Creek, a 

major tributary to the east of Malad City, and Devil Creek which 

drains a large area north of the city. These streams were gaged to 

evaluate their potential as possible sites for water-supply reservoirs. 

Currently (1968), only two stations are still in operation, Malad River 

at Woodruff and Little Malad River above Elkhorn Reservoir (Dam). 

The gaging station on Deep Creek was discontinued in 1949 8 f ter completion of Henderson Reservoir just upstream from the gag°. Miscellaneous discharge measurements were made principally during the 

late 1940's, in 1962, and in 1966. In all, streamflow at 38 sites has been 

measured either continuously through the use of recorders or inter-
STREAM AND 

1

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18

19 

20 

21 

22 

23 

24 

25

27

29

31 

32 

33 

34

36 

37 

38

 m 

o

i i

ma

mmm i 

mr3

mmmmmm

mfmmlmmmT

i

 MMI

mmmmm

.^SWM

 

D

n

n

a

Z)

 ED

a

a

a

CD

I I

1 1

1 1

I I C

mmmmm

jgeai

a

mm

mmm_-

i

en

a

a

a

n

a

n

a

a

d

a

a

en

Malad River at springs, near Malad 

Malad River below springs, near Ma

Malad River near Malad City

Malad River near Pleasantview

Malad River at Pleasantview

Malad River near Samaria (above Gw

Gwenford Mill ditch near Samaria

Malad River near Samaria (below Gw

Malad River near Samaria (2 miles b

Main Canal near Samaria (2 miles b

Diversion canal near Samaria (diver

Warm Springs Canal near Samaria

Warm Springs Canal near Woodruff

Warm Springs Canal at Woodruff

Little Malad River below springs, ne

Dairy Creek near Daniels

Wright Creek near Daniels 

Little Malad River above Elkhorn Re

Little Malad River below Elkhorn Re

Little Malad River at Ed Jones Ranc

Little Malad River at Sand Ridge dit

Sand Ridge ditch near Malad City

St. Johns Canal near Malad City

Little Malad River below St. Johns C

Little Malad River near Pleasantview

Devil Creek below Birch Creek diver

Devil Creek above Evans dividers, n

Davis Creek at source, near Malad C

Devil Creek near Malad City

Mill Creek below Evans dividers, ne

Third Creek near Malad City

Deep Creek at Malad City

Malad River at Cherry Creek Lane, n

Malad River at Woodruff

1935 1940 1945 \^ 

WATER YEAR ENDING

n 1955 1Q6D

SEPTEMBER 30

FIGTJBE 23. Length of stream-gaging records. Numbers on left re
SURFACE WATER 53

mittently by miscellaneous discharge measurements. Following the 

severe flood of February 1962, indirect measurements of p°,ak discharge were made on several streams in the basin.

The length and type of streamflow record available at each site are 

shown in figure 23. Locations of the discharge-measurement sites are 

indicated in figure 24, and pertinent descriptive data are srown on 

pages 55-57. Daily discharge records for gaging stations in th°i Malad 

River basin and the results of discharge measurements of partialrecord stations are published in U.S. Geological Survey water-supply 

papers titled "Surface Water Supply of the United States, Prrt 10."

Surface-water resources have, almost from the start, played a key 

role in the argicultural development of the Malad River basin. Shortly 

after the base flow of streams had been exhausted, numerous detention 

reservoirs were built to store runoff. The largest of these, Henderson 

Reservoir on Deep Creek, is used for irrigation and recreation. There 

is a small public water-supply detention basin just north of Malad 

City; however, virtually all other reservoirs in the project area were 

built to supply water for irrigation.

With one exception, all reservoirs have functioned satisfactorily. 

Owing to the presence of cavernous limestone deposits at the Elkhorn 

damsite (about 14 miles northwest of Malad City), the reservoir 

would not hold water except for brief periods following her.vy runoff. In the spring of 1966, construction was begun on a new reservoir on 

the Little Malad River at a point about 4 miles above the Elkhorn 

damsite. A considerable effort was made to eliminate underf ow past 

the damsite by grouting concrete deep into the streambed and the 

flanking hill slopes. Construction on the project was nearing completion in 1967. Thus, no appraisal of the success of this venture will be 

possible in the near future. If the project is a success, then part of 

the spring runoff can be stored for later use during the irrigation 

season. The storage of water that has virtually gone unusei in the 

past will permit substantial expansion of irrigated acreage in the Little 

Malad River valley by providing water for land that previously was 

used for grazing and dryfarming.

LOW-FLOW CHARACTERISTICS OF STREAMS

One of the principal goals of water management in the project area 

involves detaining as much of the spring runoff as possible in efficient 

reservoirs. In addition to a comprehensive appraisal of the subsurface 

geology of a proposed damsite, detailed information on the amount 

and variability of streamflow is also needed. In particular, the water
54 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

R 34 E

T. 105.

T 11 S.

EXPLANATION

 

Precipitation station

A18

Stream-gaging station

424 

Discontinued stream-gaging station

A20

Discharge measurements only

Basin boundary

T 12 S

T. 135

T 145

T 15 S

T 16 S

FIGURE 24 Location of stream-gaging sites and weather stations in the 

upper Malad River basin. Number beside station symbol is stream-gaging 

site number in figure 23. Letter is site listed in table 4.
SURFACE WATER 55

planner should know the low-flow characteristics of streairs in the 

basin. Statistics enabling the planner to assess the probability of specified minimum low-flow conditions for design purposes are of special 

value. The material in tables 5-9 should assist the designer by providing data on low flows. No allowance was made in these analyses for 

reservoir losses due to evaporation or seepage; therefore, allowance for 

such losses must be made in designs based on these tables.

Studies of low flow are based on the 28-year period April 1, 1932, 

to March 31, 1960 (1932-59 climatic years). Although no one record 

completely spans this period, correlation techniques permit extension 

of records of all gaging stations to estimate probable flows during the 

entire base period. Use of a single long base period eliminates inconsistencies that would arise from use of records of unequal length and 

differing periods. Moreover, when applicable, correlation techniques 

increase the value of individual gaging sites by extending their period 

of record. Two outstanding drought events are incorporated in this 

analysis, that of the 1930's and the recently ended drought which began in the 1950's. Thus, the effect of extended drought is incorporated 

in the streamflow records and is, in turn, reflected in the data presented in tables 5-9.

MONTHLY DISCHARGE SUMMARY

A streamflow summary showing the mean, maximum, and minimum 

monthly discharge in cubic feet per second, recorded at seven long-term 

stations in the basin is given in table 5. The table is preceded by descriptive information for each station. In general the highest 

discharges occur in spring and the lowest in late fall or winter.

Birch Creek near Downey, Idaho:

Location: Lat 42°21', long 112°15' SEi/4 sec. 28, T. 12 S., R. 36 E., on left

bank, just downstream from the abandoned Malad powerplant, 8.6 miles

southwest of Downey, and 10 miles above mouth. 

Drainage area : 6v56,sq- m. (revised).

Records analyzed: Oct. 1911 to July 1914, Oct. 1937 to Sept. 1949. 

Average discharge: 13 years (1911-12, 1937-49), 9.31 cfs. 

Extremes: Maximum daily discharge, 34 cfs, Apr. 24, 1943; minimum daily,

5.2 cfs, at times during Jan.-Mar. 1941. 

Remarks: Water is diverted from Birch Creek half a mile downstream from

station and carried by transbasin canal to Devil Creek in Malad River basin. 

Deep Creek below First Creek, near Malad City, Idaho:

Location: Lat 42°14', long 112°11', in sec. 7, T. 14 S., R. 37 E., just downstream from site of proposed reservoir, 1 mile north and 3% miles east of

Malad City, and 12 miles upstream from mouth. 

Drainage area: 29.7 sq. m. 

Record analyzed: Oct. 1931 to Dec. 1948. 

Average discharge: 17 years (1931-48), 9.11 cfs. 

Extremes : Maximum daily discharge, 113 cfs, Apr. 18, 1936; minimum daily,

0.3 cfs, Aug. 29,1934.
56 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHC

Remarks: Small diversions above station. 

Devil Creek above Campbell Creek, near Malad City, Idaho :

Location : Lat. 42°18', long. 112° 12', in sec. 12, T. 13 S., R. 36 E., 0.6 mile upstream from proposed dam, 4.5 miles upstream from Evans d'viders, and

7y2 miles northeast of Malad City.

Drainage area : 20 sq. m. (includes Birch Creek near Downey drainage area). 

Records analyzed : Oct. 1938 to Oct. 1961. 

Average discharge : 23 years (1938-61), 9.28 cfs. 

Extremes: Maximum daily discharge, 167 cfs, Mar. 29, 1943; minimum daily,

1.8 cfs, Nov. 3-5, 1949. 

Remarks: Diversions above stations for irrigation of 20 to 30 acres. Stream

receives part of flow of Birch Creek above station. 

Devil Creek above Evans dividers, near Malad City, Idaho:

Location: Lat 42°15', long 112°13', in sec. 35, T. 13 S., R. 36 II, at Evans

Ranch, 900 feet upstream from Evans dividers, 3.1 miles downstream from

Campbell Creek, and 3.6 miles northeast of Malad City.

Drainage area : 43 sq. mi. (includes Birch Creek near Downey drainage area). 

Records analyzed: Oct. 1940 to Dec. 1943; May 1946 to Jan. 1953. 

Average discharge: 9 years (1940-43, 1946-52), 14.4 cfs. 

Extremes: Maximum daily discharge, 173 cfs, Apr. 19, 1952; minimum daily,

1.1 cfs, Nov. 6, 1950. 

Remarks : Diversions for irrigation of 600 to 800 acres above station. Stream

receives part of flow of Birch Creek above station.

Little Malad River above Elkhorn Reservoir (Dam), near Malad City, Idaho: 

Location: Lat. 42°20', long. 112°26', on line between sees. 35 and 36,

T. 12 S., R. 34 E., three-quarters of a mile upstream from county road

bridge, 2 miles downstream from Wright Creek, and 14 mile? northwest

of Malad City. 

Drainage area : 120 sq. mi. 

Records analyzed: Aug. 1911 to July 1913, Oct. 1931 to Sept. 19S2, Oct. 1940

to Sept. 1963.

Average discharge: 25 years (1911-12, 1931-32, 1940-63), 17.7 cfs. 

Extremes: Maximum daily discharge, 721 cfs, Feb. 10, 1962; minimum

daily, 8.5 cfs, Sept. 30 to Oct. 1,1961.

Remarks: Diversions for irrigation of about 400 acres above station. 

Malad River below springs, near Malad City, Idaho :

Location: Lat 42°13', long 112°22', in sec. 10, T: 14 S., R. 3e E., half a

mile downstream from springs which form river, 1% miles upstream 

from Samaria Dam, and 5% miles northwest, of Malad City. 

Drainage area: 3.3 sq. mi. Flow derived almost entirely from springs. 

Records analyzed: Oct. 1931 to Sept. 1932; Oct. 1940 to Oct. 1947. 

Average discharge : 8 years (1931-32, 1940-47), 10.5 cfs. 

Extremes: Maximum daily discharge, 18 cfs, May 6-12, 1947; minimum

daily, 4.4 cfs, Oct. 1931 and at times during Nov. 1931. 

Remarks: No diversions or regulation above station. 

Malad River at Woodruff, Idaho :

Location: Lat 42°02', long 112°14', in sec. 15, T. 16 S., R. 36 E., at highway

bridge at Woodruff, 21/4 miles north of the Idaho-Utah State line. 

Drainage area : 485 sq. mi. 

Records analyzed: Dec. 1938 to Sept. 1963. 

Average discharge : 24 years (1939-63), 59.7 cfs.
SURFACE WATER 57

Extremes: Maximum daily discharge, 2,240 efs, Feb. 12, 1962; minimum 

daily, 8.0 cfs, July 16,1960.

Remarks: Flow regulated by several small reservoirs above station. Diversions above station for irrigation of 20,000 to 25,000 acres.

TABLE 5. Monthly sir earn flow chafacteristics of selected gaging stations

Month Mean 

(cfs)

Maximum

Cfs Calendar 

year

Minimum

Cfe Calendar 

year

Birch Creek near Downey, Idaho

July............

.. ......................-....... 7.65

.................................. 7.51

................................... 7.16

.................................... 7.15

. .._-....--..--.........__..._ 7.53

.................................... 12.4

.-...--..__--.._ ..__.-....--. 16.2

_._....--._..-..._.-.....-......... 12.7

.................................... 9.39

.................................... 8.44

.................................... 7.98

9.45 

9.40 

9.14 

8.86 

10.3 

11.1 

23.6 

21.1 

17.6 

11.8 

10.1 

9.56

Deep Creek below First Creek, near Malad City,

January--.-....

July.. ..........

.................................... 3.05

................................... 3.00

.................................... 2.97

.....rr . ............................ 2.99

.................................... 3.80

.................................... 7.07

.................................... 22.1

.................................... 26.9

.................................... 17.7

.-_...... -.._..........--.-.... 10.8

--....--.--.....-...--....-....-...- 5.56

.................................... 3.02

5.48 

4.74 

4.85 

3.96 

7.70 

16.4 

58.9 

51.2 

30.4 

14.9 

11.5 

8.20

1912 

1912 

1911 

1912 

1912 

1912 

1943 

1912 

1912 

1945 

1945 

1912

Idaho

1946 

1946 

1945 

1946 

1943 

1943 

1936 

1932 

1945 

1937 

1937 

1945

5.42 

5.24 

4.28 

5.22 

5.34 

6.06 

8.69 

9.94 

7.54 

6.97 

6.53 

6.37

0.97 

1.43 

1.34 

1.90 

2.34 

3.52 

4.64 

3.03 

2.08 

.84 

.44 

.52

1913 

1913 

1913 

1914 

1914 

1914 

1945 

1939 

1939 

1940 

1940 

1913

1934 

1934 

1931 

1936 

1937 

1944 

1934 

1934 

1934 

1934 

1934 

1934

Devil Creek above Campbell Creek, near Malad City, Idaho

July.........----.

.................................... 7.01

---...-.-...-........--..--.....-..- 7.44

.................................... 7.64

.................................... 7.59

......-.-...----...-.-.........---.. 11.5

.................................... 17.5

.................................... 10.4

7 ^7

. . -. -....-.-.. ....--.. 6.62

.................................... 6.45

10. 3 1950 

9. 95 1951 

10.0 1951, 1952 

9. 82 1952 

11. 6 1947 

25. 5 1943 

46. 4 1952 

23. 8 1952 

21. 7 1945 

11. 1 1950 

9. 29 1952 

8. 99 1951

4.47 

4.98 

5.22 

5.2? 

4.8P 

6.05 

4.9F 

5. If 

4.5f 

4.5F 

4. 40 

3.92

1960 

1959 

1959 

1957 

1956 

1961 

1961 

1961 

1961 

1961 

1960 

1961

Devil Creek above Evans dividers, near Malad City, Idaho

July... .----....

Seotember ....

.................................... 9.12

.................................... 9.77

.................................... 9.91

.................................... 9.85

.................................... 11.0

.................................... 17.5

.................................... 40.2

...--.---.-....-.-...-.-............ 26.4

......... .............. .......... 14.7

.................................... 9.34

.................................... 7.74

.................................... 7.31

11.5 

12.3 

13.1 

12.5 

18.1 

35.3 

76.7 

40.0 

23.4 

14.9 

10.7 

9.10

1950 

1950 

1950 

1951 

1947 

1943 

1952 

1952 

1950 

1950 

1950 

1950

6.5 

7.61 

7.52 

7.60 

7.67 

9 18 

17.4 

18 0 

10 0 

7.11 

5 47 

6.29

1940 

1942 

1940 

1942 

1949 

1942 

1947 

1947 

1941 

1949 

1949 

1942
58 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

TABLE 5. Monthly streamflow characteristics of selected gaging stations Continued

Month Mean 

(cfs)

Maximum M'limum

Cfs Calendar 

year

Cfs Calendar 

year

Little Malad River above Elkhorn Reservoir (Dam), near Malad City, Idaho

October _ .......................

November. ..--...-....---....-..

December............. ..........

January. ........................

February... .....................

March ......----...-.-...---.....

April.. ..._......................

May.. ---..-----..---------...--.

June.............................

July............................

AUgUSt ----.---.-..--.-__---.....

September- ......................

................... 14.2

................... 14.5

..-.....-.-.--.--.. 14.7

................... 15.3

................... 21.3

..... ...----.---.. 22.2

--- --._-.---. 23.2

..---..--.--....... 20.0

..-.....---...-.... 17.3

-.------..--.. 15.8

..-...-.-.-...-.... 14.6

-.-.--....-..--.... 13.9

17.8

17.6

18.1

22.1

88.0

50.5

41.3

34.2

24.8

21.2

22.4

17.7

1952

1950, 1952

1945, 1952

1962

1962

1962

1948

1952

1912

1912

1912

1952

10.1

11.1

11.5

12.0

12.5

13.6

13.9

12.5

10.8

11.7

11.3

10.0

1961

1961

1961

1961

1932

1932

1961

1961

1961

1963

1963

1961

Malad River below springs, near Malad City, Idaho

October. -.___.-..__.-_._..__.-__

November.. ............... ......

December. ......................

January. ........................

February. .......................

March.....---....---............

April............................

May. .,---------------...-.-._---

June......... --------------------

July....----..............--.--..

August -.--.--------..-.-----..--

September.......................

..-....--...--..... 8.07

...--__..-.-......- 7.99

................... 8.74

..........-..---.. 10.0

................... 11.0

..--... ..- 12.1

 -.--..- .---.- 13.4

-_.-..........--- 14.0

-.---.-.-.-_--.---- 12.0

...--...-.....-.... 10.2

.-.-.... ........ 9.51

................... 9.15

10.5

11.7

13.8

14.1

13.4

14.1

15.5

17.1

14.1

11.9

11.8

11.0

1946

1945

1945

1946

1944

1944

1946

1946

1945

1946

1946

1946

4.40

4.7*

6.3?

7.51

8.89

9.75

11.1

9. 90

8.0

7. 50

7.19

7.77

1931

1931

1931

1942

1941

1942

1942

1932

1932

1932

1932

1932

Malad River at Woodruff, Idaho

October.........................

November .......................

December.... ________ .........

January. _-_.---_..-____________.

February. .......................

March...........................

April. ...........................

May.............................

June.... ....-_-....--_-..........

July..-.-..----........-........

AUgUSt ---------.----.-..--..---.

S eptember. .-------..............

.................... 32.7

.....-_. . .-._. 56.4

.-.___..._.-..--._.. 69.0

.................... 66.5

..._._..._.____-_... 116

......._..........-. 129

.................... 103

.................... 53.2

..........._..--.... 32.3

..-...--...._....... 21.4

.................... 21.7

.................... 21.2

53.7

99.4

194

150

450

249

280

114

89.2

33.4

40.3

29.2

1952

1946

1946

1953

1962

1946

1952

1950

1945

1952

1952

1951

18.7

25.9

32.1

28.3

48.9

49.3

35.6

18.8

15.3

14.3

13.9

15.2

1962

1962

1962

1963

1960

1961

1961

1961

1961

1962

1963

1963

FLOW-DURATION CURVES

A useful way of portraying streamflow variability at a gaging station is to group daily discharges for the period of record into class 

intervals according to magnitude. If the number of occurrences in each 

interval is cumulated from the highest values to the lowest, then the 

proportion of the total time that flow was equal to or greater than the 

lower limit of each class can be computed. A flow-duration curve is 

prepared by plotting discharge as ordinate and time, in percentage of 

total period, as abscissa, as shown in figure 25. This graph shows that, 

at Devil Creek above Campbell Creek, streamflow was 10 cfs o*1 greater 

about one-third of the time and that it was 6 cfs or greater about 90 

percent of the time. The flat slope at the lower end of the cnrve for
SURFACE WATER 59

100

120

010

0.1 1 10 30 50 70 90 99 99.9 

PERCENTAGE OF TIME INDICATED DISCHARGE WAS EQUALED OR EXCEEDED

FIGURE 25. Daily flow of Devil Creek above Campbell Creek for tl-"> period

1932-60.

this site forecasts a dependable supply of water even during extended 

periods of drought, indicating that ground water is the sole contributor 

to streamflow during dry periods. If this were not the case, thQ< curve 

would bend sharply downward as direct surface runoff dwindled.

Flow-duration data for the 1 to 99 percentile points for seven stations are given in table 6. As might be anticipated, the most dependable

TABLE 6. Duration of daily flow at selected stations, adjusted to base period, 1932-59

[All gaging stations are "near Malad City" unless otherwise stated]

Daily flow, in cubic feet per second, at indicated gaging station

discharge equaled

or exceeded that

shown

Birch

Creek

near

Downey

Deep

Creek

below

First

Creek

Devil

Creek

above

Campbell

Creek

Devil

Creek

above

Evans

dividers

Little Malad

River above

Elkhom

Reservoir

(Dam)

Malad

River

below

springs

Malad

River

near

Woodruff

24.5

21

17

14

10.5

8.4

7.7

6.8

6.5

6.1

5.7

5.0

4.7

55

43

29.5

21

14

8.8

4.0

2.7

2.3

1.9

1.6

1.2

0.8

37

29

20.5

16

12

10

8.5

7.2

6.6

5.9

5.5

4.8

4.4

51

40

28

21

14.5

11

8.4

6.9

6.3

5.6

5.0

4.1

3.7

41

32.5

25.5

21.5

19

17.5

15.5

14.5

13.5

13

12.5

11.5

11

16.5

16

15

14.5

13

12

10.5

9.1

8.3

7.4

6.7

5.9

5.2

285

227

167

125

88

64

42.5

26.5

22.5

20

18

16

14.5
60 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

low flows are near the headwater stations, where springs and seeps 

maintain sustained discharges beyond the 90-percent duration point.

LOW-FLOW FREQUENCY CURVES

An inherent weakness of duration curves lies in the fact that it is 

impossible to obtain flow data on droughts by considering consecutive 

days as a unit. Low-flow frequency curves were designed to overcome 

this deficiency by showing how often the average discharge for prestated periods of consecutive days may be expected to equal or to be 

lower than some specific discharge.

A family of low-frequency curves for Devil Creek above Campbell 

Creek (fig. 26) was prepared for five selected periods ranging from 7 

to 274 days. The probability of a specific event occurring is expressed 

in recurrence intervals along the abscissa. For example, the 5-year recurrence interval intersects the 7-day curve at 4.5 cfs. Therefore, discharges may be expected to average 4.5 cfs or less over any 7-day period 

at intervals averaging 5 years. The probability of such an event occurring in any particular year is 0.20 (one chance in five) which is the 

reciprocal of the recurrence interval.

The well-sustained low flows at this station are again demonstrated 

by the tendency for this family of curves to flatten slightly at high 

recurrence intervals. These curves show that discharges are highly 

unlikely to average less than 3 cfs over any 7-day period at recurrence 

intervals of as long as 30 years. Low-flow data for six gaging stations 

in the basin are shown in table 7. The probability of occurrence of any 

event is expressed by recurrence intervals ranging from 2 to 30 years.

1.5 235 10 20 

RECURRENCE INTERVAL, IN YEARS

50 100

FIGURE 26. Magnitude and frequency of annual low flows for Devil Creek above 

Campbell Creek, adjusted to the base period, 1932-59.
SURFACE WATER 61

In using these tables, no regular occurrence of events is implied. For 

example, a 15-year low flow occurring in any particular year may be 

followed by another such event the very next year, or not for perhaps 

another 30 or more years. Thus the stated recurrence intervals do not 

imply a fixed probability among actual events; rather the intervals are 

an average probability for a hypothetical sequence of 15-year brought 

events.

TABLE 7. Low-flow frequency at selected stations, adjusted to base period, 1932-59

RecurG aging station rence 

interval 

(years)

Do.. ............................... ^....

Do.....-.-.--.-.... ..-....--.___....._.

Do .-.... ............ --._.. ......

Deep Creek below First Creek near Malad 

City---..---...-...-........-.............

Do.. ................................. ...

Do.. ...--.--.-.----.-....-............. -

Do.-.-------..-..-.---.-.----....-.--...

Devil Creek above Campbell Creek near 

Malad City. --.-.......-...---...----.... .

Do......................................

Do... ....... ........ ....... .......... ..

Do. . --.--.. -.-.._. ..--....-.-..-.

Little Malad River above Elkhorn ReserDo....... ...............................

Do. ........ ........---..--.--..-.--...--

Do --.. . ...... .,- -.-.

Malad River below springs, near Malad City. 

Do _ ..-----.-----.......-........_....

Do......................................

Do......................................

Malad River near Woodruff-. .........._....

Do......................................

Do......................................

Do. --.......-.--....--........-......

2 

5 

15 

30

2 

5 

15 

30

2 

5 

15 

30

2 

5 

15 

30

5 

15 

30

2

5 

15 

30

Average discharge, in cubic feet per second, 

for minimum period indicated

7-day 30-day 90-day 183-day 274-day

6.1 

5.2 

4.4 

4.0

1.8 

1.3 

.9

.7

5.6 

4.5 

3.6 

3.2

12.5 

12 

11 

10.5 

7.2 

6.2 

5.6 

5.3 

19.5 

17.5 

15.5 

14.5

6.5 

5.6 

4.7 

4.3

2.2 

1.6 

1.1 

.9

6.2 

5.1 

4.2 

3.7

13 

12.5 

11.5 

11 

7.7 

6.7 

6.0 

5.6 

20.5 

18.5 

16 

15

6.8 

5.8 

4.9 

4.5

2.6 

1.8 

1.3 

1.1

6.6 

5.5

4.7 

4.2

13.5 

13 

12 

11.5 

8.4 

7.2 

6.5 

6.1 

22 

19.5 

17 

15.5

7.1 

6.1 

5.2 

4.7

3.0 

2.0 

1.4 

1.2

7.0 

5.8 

5.0 

4.6

14.5 

13.5 

12.5 

12 

8.9 

7.8 

7.0 

6.6 

27 

22.5 

19.5 

18

7.6 

6.5 

5.5 

5.0

3.4 

2.3 

1.6 

1.4

7.6 

6.3 

5.4 

4.9

15 

14 

13 

12.5 

10 

8.7 

7.8 

7.3 

38 

31 

27 

25

DAYS OF DEFICIENT DISCHARGE

111 designing a water-supply system, the engineer must consider the 

peak demands required of the system for specified time periods. If the 

natural flow of the stream is to supply the demand, low-flow frequency 

data are inadequate to solve the problem because, during each lowflow period, discharge is less than the average for part of the period. 

Hence at times during the design period the stream is unable tc supply 

the demand. Figure 27 was prepared to show how often, on the average, 

the minimum flow for selected periods can be expected to remain below 

any specified value. For example, the daily discharge for the Devil 

Creek site may be expected to be less than 3.8 cfs for a period of 30 

consecutive days at intervals averaging 30 years. Graphs similar to 

figure 27 were prepared for all stations with suitable records, and the 

results are summarized in table 8.
62 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

7 10 20 30 60

NUMBER OF CONSECUTIVE DAYS FLOW WAS LESS THAN THAT SHOWN

FIGURE 27. Frequency of maximum period of deficient discharge for Devil 

Creek above Campbell Creek, adjusted to the base period, 1932-59.

STORAGE-REQUIRED FREQUENCY

Storage is required whenever the natural flow of a stream is insufficient to meet the demands placed on it. A mass curve may be used 

to compute the required storage needed to maintain specific rates of 

demand (drafts) during the most severe drought of record. However, 

the storage so computed may be too large because of economic or 

physical limitations. Then the cost of a smaller reservoir must be 

weighed against loss of revenue during periods of insuff ",ent flow. 

Storage-required frequency data provide information needed to 

prepare a cost analysis for this type of water problem.

The preparation of storage-required frequency data is based upon 

frequency-mass curves for the 2-, 5-, 15-, and 30-year droughts, as 

indicated in figure 28. The circles plotted in figure 28 rep^sent the 

low-flow frequency for the 5-year drought multiplied by the number of 

days in the period and plotted at that number of days. ThQ, slopes of 

the straight lines represent the allowable draft that can be maintained
SURFACE WATER 63

TABLE 8. Annual low-flow frequency for days of deficient discharge at selected 

stations, adjusted to base period, 1932-59

Gaging station

Discharge, in cubic feet per second, 

Recurrence below which flow remained coninterval tinuous for length of mininum period 

(years) indicated

7-day 30-day 60-day 90-day

Birch Creek near Downey.. ....... ...................

Do........ ........................................

Do.......-..... ...............................

Do... ....... . .. -.. ....... . . ....

Deep Creek below First Creek near Malad City _ ...

Do.... ............................................

Do .

Do . .-.---. ...... ... ...

Devil Creek above Campbell Creek near Malad City.

Do ....... .. .. . ... .......

Do.......................... ...................

Do . . - ..

Little Malad River above Elkhorn Reservoir (Dam),

near Malad C ity -- --. -

Do....... .............-.........-.....-.......

Do .

Do .

Malad River below springs, near Malad City. --------

Do. .-.-...-...-................ ...........

Do ..

Do 

Malad River at Woodruff... - . . .

Do...-- . ........ -..__..-.__......._.-... ...

Do 

Do 

2

5

15

30

2

5

15

30

2

5

15

30

2

5

15

30

2

5

15

30

2

5

15

30

6.3

5.3

4.6

4.1

2.1

1.5

1.0

.8

6.0

4.8

3.9

3.4

13

12

11

10.5

7.5

6.5

5.8

5.5

20

17.5

15.5

14.5

6.6

5.6

4.8

4.3

2.8

1.9

1.3

1.0

6.6

5.4

4.4

3.8

13.5

12.5

12

11.5

8.4

7.2

6.5

6.1

21.5

19

17

16

7.1

6.0

5.1

4.6

3.2

2.2

1.5

1.2

7.3

6.C

4.8

4.2

14.5

13.5

12.5

12

9.0

7.8

7.1

6.6

24

20.5

18.5

17

7.5

6.4

5.4

4.9

3.7

2.4

1.6

1.3

8.1

6.6

5.2

4.6

15.5

14

13

12.5

9.8

8.3

7.5

7.0

27

22

19.5

18

100 150 200 250 300 

PERIOD OF MINIMUM DISCHARGE, IN DAYS

FIGURE 28. Frequency-mass curve and storage-draft lines for Devil Creek above 

Campbell Creek for the 5-year recurrence interval, adjusted to the 1932-59 

base period.
64 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

during a specified drought by tho indicated storage. Where the slope 

of the discharge-volume-available curve is less than the allowable 

draft, then streamflow is less than draft. At the point of tangency to 

the discharge-volume-available curve of a line parallel to the draft 

rate, streamflow is just equal to the draft rate, and the vertical distance between the curve and the line is equal to the storage required 

to meet the deficiency in natural streamflow. At the point of intersection of the draft rate and the volume-available curve, tli 0, reservoir 

has been refilled by streamflow.

Data from figure 28 were used to develop the curves of storagerequired frequency shown in figure 29. Use of this curve is best 

illustrated by an example. At Devil Creek above Campbell Creek for 

a 10-year recurrence intervals and no storage, the allowable draft is 

3.9 cfs, but adding a storage capacity of 2,000 acre-feet in creases the 

allowable draft to 9 cfs. Storage-required-frequency datr, (table 9) 

have been determined for only two stations in the project area. Suitable 

damsites are scarce in the Malad Eiver basin, and only Devil Creek 

and the Little Malad Eiver appear to offer good potential for the construction of reservoirs.

5 10 

RECURRENCE INTERVAL, IN YEARS

20 30

FIGURE 29. Allowable draft frequency for storage required on 

Devil Creek above Campbell Creek, adjusted to the 1932-59 

base period.
SURFACE WATER 65 

TABLE 9. Storage-required frequency for selected sites, adjusted to base period 1932-59

Recurrence interval (years)

Natural Allowable draft, in cubic feet per second, for the

7-day amount of storage indicated, in acre-feet, uncordischarge rected for seepage or evaporation

(cfs)

250 500 750 1,000 1,500 2,000

Devil Creek above Campbell 

Creek near Malad City:

6. 0

4. 8

3. 9

3.4

7. 6

6. 5

5. 6

5. 2

8. 3

7. 1

6. 3

5. 7

8.9

7. 6

6. 8

6.2

9.2

8. 1

7.2

6.6

10. 5

8. 8

8. 0

7. 3

11

9. 7

8. 6

8.0

500 1,000 1,500 2,000 2,500 3,000

Little Malad River above 

Elkhorn Reservoir (Dam) 

near Malad City:

2

5 ____________

15---_--_----_

30 ________ _

_________ 12.

_________ 11.

_________ 11

10.

5

5

5

15. 5

14. 5

13. 5

13

17

16

15

14

18

16

15

15

5

5

18

17

16

16

5

5

5

19

18

17

16

20

19

18

17

FLOODS

Climate, physiography, and geology are the principal overall factors affecting the size and distribution of floods. Melting snow, increased precipitation, and sharply lowered evapotranspiration losses 

during the winter and early spring predispose the study area to floods 

during those periods. In addition, high-intensity rainfall in connection with thunderstorm activity occasionally results in flooding during 

the summer. A major factor affecting floods is the extensive groundwater reservoir underlying the Malad Valley. The thick sequence of 

highly porous alluvial deposits constituting the recharge area? of the 

ground-water reservoir extends for a considerable distance up the major tributary valleys and along the periphery of the Malad Valley. 

These deposits tend to absorb overland flow and thereby delay the 

arrival of runoff to stream channels. Thus, despite the rugged peripheral uplands surrounding the valley, high flows in the Malad River 

and its principal tributaries usually are subject to considerable dampening. Channel storage also is an important factor in attenuatirg flood 

peaks in the downstream reaches of the Malad River.

Although the physical environment of the basin tends to reduce flood 

peaks, antecedent conditions can lower the effectiveness of the normally porous surface deposits. For example, prior to 1962 the highest 

instantaneous discharge of the Malad River at Woodruff was 650 cfs, 

recorded in January 1943. The peak discharge of February 12, 1962, 

was 2,530 cfs, or 390 percent of the previous maximum (Thomas, and 

Lamke, 1962, p. 6). Weather records show that maximum 24-hour rain-
66 HYDROLOGY, UPPER MALAD RIVER BASEST, IDAHO

fall during the flood period was 0.38 inch at the Malad City Airport 

and 0.50 inch at Malad City. These intensities are by no me-'vns unusually high; moreover, the rainfall was well distributed throughout the 

24-hour period. By way of contrast, a 24-hour rainfall of 0.96 inch 

on February 2, 1945, produced a peak flow of less than 350 cfs. Clearly, 

other factors in addition to rainfall intensity were operative in producing the outstanding flood of February 12,1962.

The most significant antecedent meteorologic factors which had a 

direct bearing in generating the 1962 flood were temperature and 

snowfall. An extremely cold airmass dropped temperatures far below 

seasonal levels during the latter part of January and early February 

1962 (fig. 30). A moderate snowstorm in mid-January produced a snow 

cover of about 5 inches over much of the valley and greater depths on 

the surrounding uplands. Sub freezing temperatures persisted until 

early February so that the snow cover was subjected to little melting. 

The melting that did occur promptly refroze forming a glazed surface 

over the aging snow cover. Temperatures as low as 15°F doubtless 

caused some frost penetration into the ground despite the snow cover; 

thus the ground became impermeable. An abrupt change in the direction of upper airflow from north to southwest in early February induced a strong flow of warm moist maritime air to overspread the area 

at all levels of the troposphere. At the surface a complex low-pressure 

system over South Dakota triggered widespread precipitation from 

California northeastward across Idaho. In the Malad Valley, this 

precipitation began as snow on February 7, 1962, increasing the snow 

cover to 6 inches. Rising temperatures, however, changed the snow 

to rain and resulted in rapid depletion of the snow cover. The continuous low-intensity rainfall on February 10 in combination with temperatures of over 50°F accelerated the snowmelting process enough so 

that by the 12th only patches of snow remained in low-lying areas.

The loss of snow cover from the valley would not, by itself, have 

produced the high stages observed throughout the area. Th^ principal 

factor producing runoff, aside from the frozen ground surface, was 

the unseasonally high temperatures which induced melting in all parts 

of the basin. If a lapse rate of 3°F per 1,000 feet is assumed, temperatures at the highest altitudes in the basin were probably near 40°F 

during the critical flood period. The combination of rapid basinwide 

snowmelt triggered by a deep flow of warm air, frozen ground, and 

moderate rainfall of low intensity produced the extraordinary flood of 

February 12,1962. By way of contrast, rainfall subsequent to the flood 

peak was heavier than that which actually generated the high runoff. 

Streamflow, however, receded steadily after February 12 owing to the 

sharply reduced snow cover and the increased soil permeability caused 

by thawing ground surfaces.
SURFACE WATER 67

Z4 

t

LJ 

Q

io 

w

rl 0.5

0.25~1

.1 + + + 

Snow cover

l+-+-+-\ l+\ i:-|-> ,1,1

Precipitation

/

II

2500

1500

1000

20 25 

JANUARY

30 10 

FEBRUARY

15 20

FIGURE 30. Weather conditions for the period Jan. 15-Feb. 21,1962, at Malad 

City and discharge hydrograph for Malad River at Woodruff.
68 HYDROLOGY, UPPER MALAD RIVER BASEST, IDAHO

FLOOD FREQUENCY

The flood of February 12, 1962, was a very rare event which could 

be evaluated statistically if sufficiently long records were available. 

Unfortunately, streamflow records in the upper Malad Elver basin 

are far too short to permit an accurate appraisal of the frequency of 

recurrence of floods of this magnitude. Nevertheless, the records are 

of sufficient length to provide valuable information on the magnitude 

and frequency of floods having recurrence intervals as long r,s 50 years. 

Knowledge of the flood characteristics of streams provides a basis for 

designing structures to be located on their flood plains. Economic 

considerations dictate the choice of a design frequency; however, 

an evaluation of these economic factors is beyond the scope of this 

report.

On the basis of available records, the period 1939-63 was selected 

as the base period for flood analysis. Five stations have records of 

sufficient length for use in the analysis. Only one station was in 

operation through the base period; records for the other stations 

were extended by correlation with nearby stations.

PLOTTING POSITION

The analysis of floodflows starts with a listing of all annual peak 

discharges at a gaging station. These are ranked according to magnitude starting with the highest flood as 1. Plotting positions (recurrence intervals) for each flood were computed by using the formula

RI= > where RI is the recurrence interval, n is the number of 

m

years of record, and m is the order number.

Annual floods are plotted against recurrence interval on a special 

form devised by Powell (1943), and the resulting curve of relation is 

a straight line for all stations used in this report. The recurrence interval of a flood does not imply any regularity of occurrence; rather it 

is the average time that a given flood will be equaled or exceeded during 

a long period of time.

MEAN ANNUAL FLOOD

The mean annual flood at a given station is the arithmetic mean of 

the annual peak discharges in an infinitely long series of such events. 

The recurrence interval of the mean annual flood is 2.33 years, according to the theory of extreme values as applied to floods by Gumbel 

(1945). The 2.33-year flood can be determined graphically and is the 

mean annual flood used in this report.
SURFACE WATER 69

REGIONAL FLOOD FREQUENCY

Flood-frequency analysis of high flows at five stream-gaging stations shows that the basin has homogeneous flood characteristics. The 

method of analyzing homogeneity was explained by Dalrymple (1960). 

A test of homogeneity is made to ensure that all records in the basin 

have similar flood-frequency characteristics. These records were combined because a composite frequency curve based on the records for 

several stations is a better tool for estimating magnitude of future 

curves than a curve based on records for any one site. For comparing 

floods at different stations and for combining them to define regional 

flood relations, annual flood peaks are converted to a dimen^ionless 

basis. This was done by computing the ratio of floods of selected recurrence intervals ranging from 1.1 to 50 years to the mean annual 

flood at each gaging station. The median ratio of each selectee1 recurrence interval was then plotted against the corresponding recurrence 

interval to give the composite frequency curve for the basin (f g. 31). 

To define the composite frequency curve in terms of discharge for any 

site in the basin, the magnitude of the mean annual flood is required. 

This was determined by relating mean annual flood (in cubic feet per 

second) to drainage area (in square miles) as shown in figure 32. BeO 2

1.01 1.1 1.3 1.5 1.7 2 2.5 3 4 5 7 10 15 20 

RECURRENCE INTERVAL, IN YEARS

30 40 50 100

FIGURE 31. Composite frequency curve of annual floods, period 193?-63.
70 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

1000

500

200

100

50

20

10 20 50 100 200 

DRAINAGE AREA, IN SQUARE MILES

500 1000

FIGUEE 32. Variation of mean annual flood with drainage area in the upper

Malad River basin.

cause of the small number of station records used to develop the curves, 

they can be considered as only approximate representations of the 

flood-frequency* relations of the basin.

Although the base period is only 25 years, the composite frequency 

curve (fig. 31) was extended to include the 50-year flood. Butler, Reid, 

and Berwick (1966, p. 8) have developed regional frequency curves 

for the Great Basin, and the extension of the upper Malad Jliver basin 

flood curve beyond 25 years is based on the shape of these regional 

curves. The curve developed in this report plots between those for two 

large flood regions (A and B) as outlined by Butler, Reic1 , and Berwick (1966, pi. 2). The position of the upper Malad River basin flood 

curve seems to be consistent with the Great Basin regional flood curves 

because the study basin is in the western part of flood region A and near 

the boundary separating flood regions A and B. Because such boundaries are only approximate, it is reasonable to expect that a curve por-
SURFACE WATER 71

traying the flood characteristics of the study basin should reflect a 

transition between the major Great Basin regional flood zones.

The procedure for determining the magnitude of floods at any 

stream site in the upper Malad River basin which is not subject to regulation is as follows:

1. Determine the size of the drainage area, in square miles, above the 

selected site.

2. By positioning the drainage-area value on the plotted line in 

figure 32, determine the mean annual flood for the site.

3. From figure 31 determine the ratio to the mean annual flood for the 

selected frequency of recurrence.

4. Multiply the ratio of the selected flood to the mean annual flood 

(step 3) by the mean annual flood determined in step 2 to obtain 

the flood magnitude at the site. If a complete frequency graph is 

desired, repeat steps 3 and 4 for a number of recurrence intervals.

Maximum known stages and discharges of the five gaging stations used

in the flood-frequency analysis are shown in table 10.

TABLE 10. Peak discharges at gaging stations used in flood-frequency analysis

Drain- Period 

Gaging station age area of 

(sq mi) record

Malad River at Woodruff. ..

Little Malad River above 

Elkhorn Reservoir 

(Dam), near Malad City. 

Devil Creek above Campbell Creek, near Malad 

City. 

Devil Creek above Evans 

dividers, near Malad 

City. 

Deep Creek below First 

Creek, near Malad City.

485 1939-63

120 1932, 

1941-63

120 1939-61, 

19632

'43 1941-14, 

1946-52

30 1932-49

Maximum floods An

Dis- Gage ( 

Date charge height ci 

(cfs) (feet) per

Feb. 12, 2, 530 8. 93 

1962 

Feb. 10, 1, 450 4. 85 

1962

Feb. 1, 585 ..........

1963

Apr. 19, 261 5. 79 

1952

1937

sal mean Ratio of 

ual flood maximum 

Qs.33 in to 

ibic feet Q2.33 

second)

315 8. 03 

150 9. 67

70 8. 36 

94 2. 78 

75 2. 29

1 Includes Birch Creek near Downey drainage area.

2 Operated as a partial-record gaging station.

WATER QUALITY

All natural waters contain chemical substances in solution. Virtually 

all the elements and compounds found in nature are, in varying degree, 

soluble in water. Precipitation commonly contains trace amounts of all 

the major chemical constituents and some of the minor constituents. 

As it moves through a basin, water originating as precipitation commonly contains progressively more dissolved solids largely as r result 

of coming into contact with additional soluble minerals of rocks and 

soil particles before reaching the stream. At high stages, especially 

during floods, the salt concentration of the base flow is diluted by 

snowmelt and direct surface runoff.
72 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

The chemical quality of streamflow in the upper Malad Piver basin 

was evaluated on the basis of 11 water samples obtained from all major 

perennial watercourses during the period August 7-8, 1967. The 

samples were analyzed by the U.S. Geological Survey laboratory at Salt Lake City, Utah. Stream discharges were at or near 

their lowest seasonal levels during the sampling period. Accordingly, the dissolved-solids content of the sampled reaches WPS probably 

somewhat greater than at any time since the previous fall. Hardness (expressed as calcium carbonate) ranged from 148 mg/1 

(milligrams per liter) at Deep Creek below Henderson Keservoir to 

588 mg/1 at the Malad Kiver gaging station at Woodruff, anc1 dissolvedsolids content ranged from 200 mg/1 at Birch Creek to 3,780 mg/1 at 

the Woodruff gaging station.

Table 11 shows the concentration of the major chemical constituents, 

in milliequivalents per liter of all samples obtained during the study 

period. Streamflow in the middle and upper parts of the basin has 

moderate to low dissolved-solids content ranging from 200 to 350 mg/1. 

As illustrated in figure 33, the chemical quality of the streams north of 

the lower Malad Valley is fairly consistent. These waters are of the 

calcium bicarbonate type that is, calcium and bicarbonate, expressed 

in milliequivalents per liter, constitute more than 50 percent of the 

major cations and anions, respectively. Dissolved-solids content increases gradually in the downstream direction on each of the three 

principal tributaries of the upper Malad River. This is partly due to 

the solvent action of water as it flows through the alluvium of the tributary valleys. The close shape correspondence of the kite diagrams at the 

source of the Malad River (which begins immediately below Big Malad 

Springs) with those for the Little Malad River suggests that the bulk 

of the flow at the springs originates as streamflow from the Little 

Malad River.

The kite diagrams for samples from the Malad River at Cherry 

Creek Lane and the Woodruff gaging station are in sharp contrast to 

diagrams for samples collected elsewhere in the basin. Streamflow at 

Cherry Creek Lane was only about 1 cfs at the time of the survey. The 

bulk of this water was probably return flow from irrigation mixed 

with some highly mineralized ground-water inflow from the saline 

areas just above the sampling site. The progressive deterioration of 

water quality downstream from Cherry Creek Lane is due almost 

entirely to the strongly mineralized waters from the Woodruff Springs. 

Sodium and chloride are the principal ions in the reach of the Malad 

River between Cherry Creek Lane and the Woodruff gage in contrast 

to the calcium-bicarbonate waters sampled elsewhere.
Henderson Malad below Creek near City DeepReservoir, 

37 sec. ............................. 0730 ...... R. 14 18ab). (T.S.,E 

at Malad 14 R.Creek near City Deep 191,(T. S.,Highway 

 36 sec. ................................. ....... 0800 ...... lOac) E.,

' 14 R.36Malad ner 0840 5Creek Devil CityS., 18dd). (T E.,sec. 14 35near ...... Johns CanalR. StMalad 0900 (T. S.,2M). CityE.,sec. 

near 14 R.at35River Malad City(T. S.,E springs, 

 ----------------- ---...... 1 0915 sec.9ad)_..---~~ 

River above Elkhorn Reservoir near Malad Little(Dam), 

34 sec. 132 Malad R.0945 (T.E.,35-36)...--.......-.-.. City S.,11 35near Daniels R.sec. 1040 '1.5Creek (T.S.,Dairy E.,18bc)..-.. 

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1967 8, August 

sec. 16 245.1481 2R. 361015 238.80077 at2.9650.31 8.26Malad River Woodruff 8.0 1653.3 E.,15dc)..-..- 0.01 (T. S.,3,780 625

at near Woodruff Creek 15Malad River CherryLane, (T. S.,

R. ........... ........................ '1 43sec. 2 5.6016.31 8.3643.02 36145 4.0013.20 63 7.42.16 8.1E.,28da) 1,59022 

near Malad 13 above Evans Creek Devildividers, (T.City 

 '8 11-...--.-- --..--.-.. .55420 sec. .4 111562.56 17413.2735 11259 43435cc).... 7.9 S.,R.36E., 

12 R.36150 '610sec. 6.4 2.0816.18302 200.2741 3.6748 7.7 (T. E.,S29db)...- BirchCreeknearDowney 

1967 7, August 

CO 

»-!

ST

H

S

(cfs) Discharge 

Temperature 

(°C)

) 2 (SiO Silica 

ppm

' Calcium 

(Ca)

Magnesium 

(Mg)

e; + Sodium 

y potassium 

£ (Na+K) 

p Bicarbonate 

g ) 3 (HC0

~ Sulphate 

» (SOi) 

2 Chloride 

(Cl)

Nitrate 

)8 (N0

H per Parts 

2w million 

2.W

*f 8" per Tons 

o. acre-foot 

sodium Percent 

adsorp- Sodium 

ratio tion 

conduc- Specific 

microm- tance 

C 25° at hos 

PH

h 

> 

6

r 

p

H

C 

cCT

O

S

1

«c 

o

CT O

«s

s

g

c 

c

o

c

5

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CT 

S

O

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o

CT

5

t

CT

S

s

s

r 

c* 

C 

CT

<; 

o

^
74 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

R.34E.

T. 10 S

T.11S

EXPLANATION

Na + K , 1 Cl

so <

Ca HCOa+COs

10 meq/l

T 12 S

T 13 S

T 14 S

T.15 S

T. 16 S

42"00f L ' 

FIGURE 33. Chemical quality of surface water in the upper M'alad Biver basin.
SURFACE WATER 75

According to the method of classifying waters for irrigation devised 

by the U.S. Salinity Laboratory Staff (1954), nine of the 11 surfacewater samples obtained during August 1967 fell in the medium salinity 

hazard (C2) and low sodium hazard (Si) classifications. TTe only 

exceptions to these uniform classifications were the samples obtained 

from the Malad River at Cherry Creek Lane and Woodruff. As denned 

by the U.S. Salinity Laboratory Staff (1954), it is possible to use waters 

in the C2 salinity classification if a moderate amount of leaching 

occurs. Plants with moderate salt tolerance can usually be grown 

without special practices for salinity control. Waters in the SI sodium 

classification can be used for irrigation on almost all soils and involve 

little danger of the development of a sodium problem. However, 

sodium-sensitive crops, such as stone-fruit trees and avocados, may 

accumulate injurious amounts of sodium in the leaves. Waters from 

the Malad River in the reach between Cherry Creek Lane ?nd the 

Woodruff gaging station should not be used for irrigation because of 

the very high salinity hazard and medium to very high sodium (alkali) 

hazard.

STREAM TEMPERATURE

At any given instant, the water-temperature pattern in a stream 

reach is largely dependent upon the net energy flux to the reach. If 

the incoming energy from all sources exceeds that leaving the water 

body, temperatures rise, whereas a net outward energy flux causes 

temperatures to fall. Little or no change in stream temperature can 

occur when the incoming and outgoing energy sources balance each 

other.

The principal sources of energy include incoming short-wave (wave 

lengths of less than 2 microns) solar radiation and atmospheric longwave radiation. Countering these incoming sources is the outward 

directed thermal radiation of the stream itself. Short-wave solar radiation reaches the stream as either direct or diffuse energy. During the 

day the net flux of energy from all sources generally is directed downward toward the stream. At night short-wave radiation is nonexistent so 

that, except under unusual atmospheric conditions, the net flux is 

from the stream to the atmosphere.

In addition to these radiant forms of energy transfer, evaporation 

and conduction take place at the water surface. Evaporation may 

entail a substantial loss of energy from the stream and is, therefore, a 

cooling process. The conduction of sensible heat from the stream to 

the air or in the opposite direction may be a significant factor where 

large temperature differences exist between the stream and the 

atmosphere.
76 HYDROLOGY, UPPER MALAD RIVER BASEST, IDAHO

111 general, the above factors are of paramount importance with 

regard to water temperatures; other energy sinks and sources are 

usually negligible. Local geologic, topographic, or hydrologic conditions, however, may create unusual thermal imbalances that exert 

considerable control on temperature. For example, the seasonal fluctuation of water temperature of two streams on Long Island was 

found to be considerably less along reaches receiving heavy groundwater inflow than in reaches where such inflow was of lesser magnitude. 

(Pluhowski, 1961, p. D55-D58). The advection of a disproportionate 

quantity of energy from the ground-water reservoir was the dominant 

factor controlling the temperatures in the middle reaches of the 

streams. Moore (1964, p. D185-D189) found that stream temperatures 

in Oregon in east-west oriented streams are 2° to 4°C warmer in July 

than temperatures in north-south oriented streams. This is due to the 

fact that east-west oriented streams receive 5 to 20 percent more solar 

radiation than do north-south trending rivers (Geiger, 19C5, p. 202). 

Clearly, the temperature regimen of any stream reach is a function 

of many complex interrelated parameters.

Thermal patterns in the basin were determined by a series of temperature observations made in three watercourses on August 15, 1966 

(fig. 34). Sky conditions were clear throughout much of the day; 

only a few high scattered cirrus clouds were observed during the 

afternoon. Both the level of atmospheric haze and the percentage of 

relative humidity were low so that ineteorologic factors produced 

nearly ideal conditions for the transfer of large amounts of solar 

energy. Air temperatures were 43 degrees to 94 degrees F, for a range 

of 51 degrees F a large daily fluctuation even for the semiarid Malad 

Valley.

Water temperatures at the source of the Malad River below Big 

Malad Springs fluctuated little despite the strong downward flux of 

radiant energy. The measurement site at this point was at the outlet 

of a small pond created by gravity springs. It is likely that the 

temperature of the spring water entering the pond was constant 

throughout the day. Therefore, the small temperature fluctuation 

observed at the outlet of the pond was due to energy exchanged at 

its surface.

Water temperatures fluctuated nearly 17° C during the day in 

the Malad River near Cherry Creek, a point about 12 miles below 

the source. The discharge at this site was less than 0.5 cfc, owing to 

upstream diversions and natural channel losses. Sluggish flow combined with a high ratio of water surface area to volume produced 

the large observed temperature fluctuation. Stream temperatures at 

this site reached a maximum about 2 hours earlier than air temperature. Owing to the north-south orientation of the Malad River at
SURFACE WATER 77

St. Johns Canal near Malad City 

Malad River below Big Malad Spring

12p.m.

FIGURE 34. Air and stream temperatures on Aug. 15, 1966, at selected sites

in the Malad Valley.

Cherry Creek Lane and to 10-foot-high banks, considerable shading 

overspread the stream by midafternoon. With the ensuing reduction 

of solar energy, there was a reversal in net energy flux, causing water 

temperatures to fall earlier than expected.

During the irrigation season the entire flow of the Little Malad 

River is diverted into St. Johns Canal. Accordingly, thermal patterns 

in the canal are representative of those in the Little Malad Eiver. 

Water temperatures in the canal fluctuated between the temp «,rature 

ranges previously discussed; the observed range was less than 6° C. 

The discharge (about 10 cfs) and the depth-width ratio were substantially greater in the canal than at either of the other sites 

where temperature was measured. As a consequence, the low ratio 

of water surface area to volume in the canal attenuated temperature 

variations. Highest temperatures in the canal occurred after the 

time of maximum air temperature owing to a slow rate of energy 

release which resulted from the relatively large quantity of stored 

heat in the water.
78 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

GBAIN-SIZE DISTBIBUTION IN STBEAM CHANNELS

In general, the rate at which streambed particles decrease in size 

in the downstream direction is relatively rapid in the upstream 

reaches of streams (Leopold and others, 1964, p. 191). Even a cursory 

examination of streambed material will corroborate the validity of 

this statement along most reaches in the project arer. Angular 

boulders are common in high-altitude ephemeral washes; wellrounded boulders and cobbles may be found in the upper reaches 

of perennial streams; and fine gravel, silt, and clay predominate in 

the do\vnstream reaches of virtually all major watercourses in the 

basin.

Two streams, the Little Malad River and Devil Creek, were selected 

for field analysis to obtain quantitative data on streambed material. 

The pebble-count method was used. At each site 100 pebbles were collected at random from the streambed. Measurements of the three 

principal axes of each pebble were made, and the pebbles were 

ranked according to size (minimum 2 mm). The number of pebbles 

in each size category was determined. The resulting totals were then 

cumulated from the smallest to the largest category and plotted on 

semilogarithmic paper to analyze particle sizes in each selected reach.

The largest particles in the streambed of Devil Creek were found 

in an ephemeral wash below the point where the stream f rst has an 

identifiable channel. The D50 (the diameter exceeded by 50 percent 

of the grains) point is about TO mm (fig. 35). A sharp reduction in 

grain sizes was observed near the former stream-gaging station above 

Campbell Creek and in the reach above Evans dividers. These sites are 

5 and 8.5 miles, respectively, below the upstream ephemeral sampling 

point. The D50 grain size is about 10 mm at both sides; however, fewer 

large particles were found in the reach above Evans dividers. Thus, 

grain sizes decrease rapidly in the uppermost reaches of Devil Creek 

but much more slowly farther downstream.

The same general pattern of decreasing grain sizes in the downstream direction is exhibited in the channel of the Little Malad River 

(fig. 35). The sampling site in sec. 26, T. 12 S., R. 34 E., is about half 

a mile below the point where the combined flow of Dairy Creek and 

Wright Creek enters the river. The D50 grain size at thir station is 

about 90 mm, whereas it is 60 mm just below Elkhorn Dam, 4 miles 

downstream. A sample of the bed material from Dairy Creek (fig. 35) 

had grain sizes considerably smaller than those measured at either site 

on the Little Malad River. The bulk of the coarse material in the 

Little Malad River, therefore, must be derived from Wright Creek, 

whose channel contains numerous boulders and cobbles.
SURFACE WATER 79

STREAM

Devil Creek above Birch Creek diversion 

Devil Creek above Campbell Creek 

Devil Creek above Evans dividers 

Birch Creek at Ranger campsite

LOCATION KEY 

NWi/4 NEi/4 sec. 34, T. 12 S., R. 36 E. 

swi/4 swi/4 sec 12, T. 13 s., R.se E. 

SWViSWVi sec. 35, T. 13 S., R. 36 E. - 

SEViNWVi sec. 29, T. 12 S., R. 36 E. - 

100

10 20 50 100 

PARTICLE SIZE, IN MILLIMETERS

200 500 1000

STREAM 

Dairy Creek

Little Malad River below Wright Creek 

Little Malad River below Elkhorn Dam

LOCATION KEY 

S£1/4NEi/4 sec. 13, T. 11 S., R. 34 E. - - 

SWViNEVi sec.26, T. 12 S., R. 34 E. - 

SWi/4 NWi/4 sec. 7. T. 13 S., R. 35 E. 

10 20 50 100 

PARTICLE SIZE, IN MILLIMETERS

200 500 1000

FIGURE 35. Grain-size distribution of selected samples of streambed material in

the Malad River basin.
80 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

WATER MANAGEMENT

The quantity of Avater available for irrigation in the upper Malad 

River basin is far short of that required to supply all suitable agricultural lands. A principal objective of water management is to distribute 

the available Avater so that optimum beneficial use may be derived 

from the existing supply. Such factors as Avater rights, definitions of 

maximum beneficial use, and conflicting economic and political interests often complicate the task of making a Avater-rranagement 

study and of carrying out technical recommendations. Water problems 

involving surface supplies are generally apparent and the law may 

be applied to settle litigation. Serious misuse of surface-water supplies 

is usually avoided because users and managers are instinctively aware 

of the more obvious instances of nonbeneficial practices. Unfortunately, the situation with regard to ground-Avater management is not 

so readily apparent. The response of aquifers to pumping is relatively 

sloAv, so the effects of stresses on the ground-Avater system cannot be 

predicted with any great degree of precision.

Ideally, efficient basimvide water management generally implies the 

conjunctive use of ground-Avater and surf ace-Avater resources. This can 

be achieved because aquifers are basically nonstructural storage reservoirs and are therefore analogous to surface reservoirs. Accordingly, 

systems-analysis techniques such as linear and dynamic programming 

can be used to suggest optimal operating procedures and to evaluate 

maximum accrued benefits within an existing framework of economic, 

legal, and physical constraints.

The ground-water reservoir underlying the Malad Valley may seem 

to contain an inexhaustible supply of potable Avater. In fact the aquifer 

system does contain a large supply of stored Avater, but its quality 

ranges widely from very poor to excellent. Although the reserve of 

fresh ground water has been adequate to meet most demands, the supply can be seriously depleted by excessive pumpage which leads to 

increased pumping costs, deterioration of water quality, and reduced 

yields from Avells. Data currently available are not adequate to determine what is excessive. Wells must produce a cone of depression in the 

water table or lower artesian heads if they are to yield water. Lowering of water levels within an aquifer system is essential if its potential 

is to be achieved. A major objective of ground-Avater management is 

to determine an aquifer's limitations and to operate Avithin those constraints. Continued decline of \vater levels during periods of normal 

or above-normal recharge may be a danger signal. As shown in figure 

21, pressure heads and Avater levels have been declining for many years 

in parts of the Malad Valley. No doubt drought and deficiert recharge 

intensified this trend, but it is unlikely that drought was the sole cause 

of the decline.
WATER MANAGEMENT 81

To gain an understanding of the internal state of the aquifer system, 

one must (1) define the principal hydrogeologic controls, (2) determine the subsurface boundaries of the ground-water reservoir, (3) 

evaluate the spatial distribution of transmissivity and storage coefficients, and (4) assess the quality of the water within the system. 

Little information is currently available in the upper Malad River 

basin regarding any of these important ground-water considerations. 

Clearly, the current program of water-level observations should be 

continued. Moreover, an expanded program of ground-water investigation must be instituted to provide data needed for the assessment 

of the basin's ground-water resources.

As noted elsewhere, surface-water users in the basin generally are 

proficient in managing their small water supplies. However, attempts 

to store part of the excess water generated by spring freshets for use 

during the irrigation season have been only partially successful. Henderson Reservoir and Deep Creek Reservoir on Deep Creek are usually 

filled following the normally heavy late winter and early spring 

runoff, and the bulk of this water is used for irrigation. Elkhorn Reservoir on the Little Malad River failed from the start to held any 

appreciable amount of water, owing to large bank and underflow 

losses. Samaria Reservoir on the Malad River is much less dependent 

on spring runoff because it receives a steady supply from springs and 

seeps. Only small diversion dams have been built on Devil Creek, 

although several suitable sites for larger dams are available. Owing 

to the generally poor quality of the streamflow at the Woodruff gage, 

especially during low-flow periods, it is doubtful that this water can 

be stored for downvalley irrigation without first diluting it with fresh 

water.

Eradication of phreatic growths, efficient irrigation practices, and 

salvaging water lost by evapotranspiration are perhaps th<^ most 

promising approaches for increasing the efficiency of water use in the 

basin. By first lowering water levels 30 to 50 feet in areas where ground 

water is lost by evapotranspiration and then maintaining these levels, 

it should be possible to salvage part of the natural discharge from 

the ground-water reservoir. However, as water levels decline, some loss 

of streamflow may occur, especially in reaches that normally receive 

part of their flow from ground-water seepage. Ground-water discharge 

by evapotranspiration is widespread in parts of the lower Malad 

Valley. In these areas the soils consist of fine-grained mater: al that 

is saturated with precipitated salts. The poorly drained tight soils 

are not conducive to leaching, so it is doubtful whether such land 

could be of economic value for agriculture. In other parts of thQ, basin, 

it should be economically feasible to combine ground-water roclama-
82 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAHO

tion projects with programs designed to remove low-benefit phreatic 

vegetation. Decreasing evapotranspiration loss in areas of phreatophytes while depleting streamflow within allowable limits would 

increase the beneficial use of water in the basin by an amount equivalent to the water salvaged.

Although State law prohibits waste of water from artesian wells 

(McGuinness, 1951, p. 19), many flowing wells in the lower Malad 

Valley remain uncapped throughout the year. Some water users maintain, however, that the winter flow is not wasted. In their opinion, this 

flow is necessary to flush salts from the fields. Nevertheless, leaky or 

uncased artesian wells are numerous and these contribute to reductions 

of pressure and storage and to the basin's overall water loss. Much 

of the water from uncapped artesian wells is applied continually to 

large tracts of land that are now waterlogged. Repairing poorly constructed and leaky artesian wells would be a useful step in curtailing 

the inefficient use of ground water.

SUMMARY AND CONCLUSIONS

A thick sequence of interbedded clay, silt, sand, and gravel deposits 

of highly variable horizontal and vertical permeability constitutes the 

ground-water reservoir underlying the Malad Valley. The thickness 

of this unconsolidated material is greater than 700 feet locally; its 

total thickness is not known. The project area has extensive reserves 

of stored ground water which have fostered irrigation in the valley, 

especially south of the latitude of Malad City where arteHan conditions are prevalent. Since the end of World War II, increased pumpage 

and protracted drought have steadily lowered artesian pressure heads 

in many parts of the lower Malad Valley. Runoff from the hard-rock 

mountainous areas around the periphery of the basin is one of the 

main sources of recharge to the ground-water reservoir. Th°s principal 

direction of grbund-water movement is southward in the Malad Valley 

(figure 3) and generally parallel to the longitudinal axes of the principal tributary valleys. Discharge from the ground-water system is 

by evapotranspiration, springs, seepage to streams, pumping, and as 

underflow past the constricted lower Malad Valley.

The orientation of the mountain ranges east and west of the study 

area orthogonally to the prevailing eastward flow of air creates an 

environment that is very efficient in removing atmospheric moisture. 

Runoff from the high elevations of the basin is from eight to nearly 

20 times greater than that generated in low-lying areas.

The principal climatic controls are the large-scale surface and 

upper-air centers of atmospheric action that govern the flow of moisture to the basin. Owing to its inland position and the numerous
SUMMARY AND CONCLUSIONS 83

meridional mountain ranges to the west, a minimum uplift of 6,000 

feet is applied to airmasses moving over the basin from the Pacific 

Ocean. Consequently, the precipitable water of originally moist airmasses is largely depleted long before the airmasses reach the Malad 

River basin. In addition, migratory low-pressure systems are often 

diverted away from the project area by high pressure that normally 

develops in the atmosphere over the Great Basin. The characteristic 

sinking motion of the air in high-pressure systems tends to further 

desiccate the atmosphere. This combination of factors is largely 

responsible for the semiarid climate of the Malad basin.

Ephemeral streams are common to much of the basin, particularly 

in the mountains and the lower Malad Valley. Stream channels are 

well defined in the uplands; however, most of them rapidly become 

indistinct after moving onto the alluvial fans that surround the 

Malad Valley. The principal streams of the basin are perennial, except 

below reaches where the entire flow is diverted into canals for irrigation or in the lower Malad Valley where seepage losses may reduce 

flows to zero. Perennial streams are supplied by gravity springs that 

characteristically discharge fairly uniform quantities of water.

Streamflow records in the basin were first collected in 1911; however, 

a continuing stream-gaging program did not begin until 1931. Lowflow and flood analyses were prepared for several long-term stations 

covering a 29-year base period, water years 1932-60. Well-sustained 

low flows characterize the upper reaches of most perennial streams, 

but greater discharge variability and therefore less reliability are 

common in the lower reaches. A regional flood-frequency analysis of 

the basin shows that at the 50-year recurrence interval, peak instantaneous runoff values of 16.5 cfs per sq mi may be expected from 

drainage areas of 20 sq mi; 11 cfs per sq mi from drainage areas of 

50 sq mi; and 8.5 cfs per sq mi from drainage areas of 100 sq mi.

As in many other parts of the Nation, storage of surface-water 

resources by the construction of dams and reservoirs is limited in the 

Malad River basin owing to a scarcity of suitable sites. Two streams, 

Devil Creek and the Little Malad River, may be suitable for limited 

water development. A moderate supply of water is available in both 

streams, particularly if some storage is provided.

Stream temperatures are a function of many interrelated variables, 

so water-temperature fluctuations may differ considerably from point 

to point along a stream. The range of water temperatures on a clear 

summer day was observed to be 1°C at a point near the source of the 

Malad River to almost 17 °C in a reach 12 miles downstream. Spring 

flow at the source kept stream temperatures within a very narrow 

range, whereas a high ratio of water surface area to volume at the
84 HYDROLOGY, UPPER MALAD RIVER BASIN, IDAFO

downstream site permitted high solar-radiation absorptior to produce 

the large observed fluctuation.

The grain size of streambed material in Devil Creek decreases 

rapidly below the headwaters of the stream. The D50 size (the diameter exceeded by 50 percent of the grains) at the source is 70 mm, 

whereas at a point 5 miles downstream it is only 10 mm. The bulk 

of the coarse material in the Little Malad River is derived from 

Wright Creek rather than Dairy Creek, which has a preponderance 

of relatively fine-grained bed material. There is a gradual downstream 

siae reduction in streambed material in. both the Little Malad River 

and in the middle and lower reaches of Devil Creek.

The computed mean annual water yield of the project area is about 

115,000 acre-feet per year, which is equivalent to 4.0 inches over the 

basin. The mean annual outflow from the basin is computed to be 

51,000 acre-feet of surface water and 28,000 acre-feet of ground water. 

The difference between input and output is largely accounted for by 

evapotranspiration losses, especially from irrigated areas. Mower and 

Nace (1957) have estimated losses from phreatic growths at 37,000 

acre-feet. Accordingly, decreasing evapotranspiration in ar?.as infested 

by phreatophytes could substantially increase the beneficial use of 

water in the basin. Efficient use of the water resources of the basin 

would be of direct benefit to agriculture, as thousands of acr^s of fertile 

land could be brought under irrigation by salvaging this water.

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Howell, G. F., 1960, Early history of the Malad Valley: Brigham Young Univ.

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Klein, W. H., 1956, Some empirical characteristics of long waves on monthly mean

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REFERENCES CITED 85

Landsberg, Helmut, 1958, Physical climatology: Du Bois, Pa., Gray Publishing

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of Malad and Curlew Valleys, Oneida County, Idaho: U.S. Geol. Survey

open-file rept., 140 p.

Thornthwaite, C. W., 1948, An approach toward a rational classification of climate : Geog. Rev., v. 38, p. 55-94. 

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floods in the Snake River basin: Weather Bur. Coop. Rept. 11, p. 11. 

 1961, Rainfall frequency atlas of the United States: Weather Bur. Tech.

Paper 40,115 p. 

U.S. Salinity Laboratory Staff, 1954, Diagnosis and improvement of saline and

alkali soils: U.S. Dept. Agriculture Handb. 60,160 p. 

Van Hylckama, T. E. A., 1959, A monogram to determine monthly potential evapotranspiration : Monthly Weather Rev., v. 87, no. 3, p. 107. 

Williams, G. R., and others, 1940, Natural water loss in selected drainage basins:

U.S. Geol. Survey Water-Supply Paper 846, 62 p.
INDEX

[Italic page numbers indicate major references]

A Page 

Agriculture ...................... _ ..... 9

development. 10

length of growing seascn--_-_._-_._ ......_ 14

Alfalfa _-.--_ ._..----. .- _-_- 11,32

Alkali-.....-...-...-.......-.- ......... 3

Alluvial fans 

Altitude, Malad Valley. 

Aquicludes- ............

Aquifers---------------

 7

.----___._ 7

.... .-. ..... 39

------.-..----- 39

artesian. ------._-..-------.----_-. 2,3,10,44

water-table- . . ....--.-.-.-...-.-.-.... 44

Artesian ground water-..-. ______ ........... 39

Artesian wells ------------------.-.------.-- 3,82

Aspen. .. ...... ... ...... ..----- ------. .- 11

Atmosphere, circulation patterns. -..-.-.- 12

Avocados- -.----------------_-_----_-_-_ -__ 75

Bannock County. _ -_- 3

BannockRange. -__..---.----.--.-_-_-._. _3,7,38 

Barley..--.. --- ----. ---- ..--- 10

Basin and Range physiographic province..... 7

Bear River.-.._._._.. .....--._......-...-. 9

Big Malad Springs--...... ..-.- 76

Birch Creek...-.---------.-....---- 10,38,43,49,72

Birch Creek near Downey, gaging station. _. -. SB 

Blue Spring Hills---..-------------------- 3,7,38

Bonneville shoreline. -._._. ___.___ 38

Campbell Creek... .-.-. ---.-..-.. 38,50,78

C apillary water....-.-................. -.-.. 48

Caribou Range................... ..... ... 27

Cattails---------------------------------- 11

Cattle-----.-------------.------. ----- 10

Cherry Creek.... ........... ...... ... 43

Cherry Creek Lane_........................ 45

Circulation patterns. 18,20

Climate, Aleutian low..- - .- -------- 11

analysis of records. - . - 27

controls---- --------------------- 11,27,82

eastern Pacific high................... .. 12

Great Basin high..__............ .... . 11

Crops-.-------------------------------- 10

D 

Dairy Creek...-._.__-..___.------...-- 78,84

Daniels ---------------------------------- 10

Davis Creek, reservoir. ..................... 1C

Deep Creek--. 7,48,51,53,72,81

Deep Creek below First Creek, near Malad

City, gaging station SB

Page 

Deep Creek Reservoir. 10,81

Desert saltgrass. -- _ 11

Devil Creek.----------. _. 7,10,38, 50, 5',81,83,84

reservoir potential.__-- 64

Devil Creek above Campbell Creek, near

Malad City, gaging station.----- 51,

55,58,60,64 

Devil Creek above Evans dividers, near

Malad City, gaging station....... 66

Discharge, artesian wells.------------------ 3

Devil Creek-....---...-.-------- 61

Malad River at Cherry Creek Lane------ 45

Malad River at Woodruff- --__-__--- 45,65 

Dissolved-solids content, surface water. ------ 72

Drought -- n

E

Elkhorn Reservoir (Dam) .....--.. . 10,38,78,81

unsatisfactory............................ 53

Ephemeral streams. 7,83

Equation, recurrence interval . 68

underflow 49

water loss. - __ - - 31

water yield..... -------------------------- 32

Evans dividers.-----..---------------------.- 56,78

Evaporation . _ --- - .- 30,32

Evapo transpiration. .--_---_._--- 16, SI, 45,49

definition . 31

Long Island, N.Y-.......----_--. -_-_- 34

losses.. ------------ 4

potential---_ - - 34, 50

Thornthwaite's method. - ____-_ 32, 50

Williams plot ..... -------------- 35

Faults -- - - - - 3,33,39,45

Fir. 11

Floods BB

magnitude determination .... .....--. 71

Malad Valley-- 66

Flow-duration curves, surface water.._._. __ 58

Flowing wells, Malad City. - - - - 10

Forage crops 10

Franklin County-. - 3

G

Gaging stations:

Birch Creek near Downey 55

Deep Creek below First Creek, near

MaladCity ------------------ 55

Devil Creek above Campbell Creek, near

Malad City.. -------- 51,55,58,60,64
88 INDEX

Gaging stations Continued Page 

Devil Creek above Evans dividers, near

Malad City.-..----.-_...-._----- 56

Little Malad River above Elkhorn Reservoir (Dam), near Malad City-... 51,56 

Malad River at Cherry Creek Lane. - _ _. _ 72 

Malad River ar Woodruff. ---___..___.... 45,

49, 50,51, 56, 65,72,75,81 

Malad River below springs, near Malad

City --....--.....-_...__.-..... 56

Portneuf River at Topaz Station. -.-.-___ 35 

Willow Creek near Ririe ............... 35

Geography.-.---. -___._-.____..____...___.___ 6

Grain-size analysis, streams_. -_......______ 78

Gravity springs.............................. 76,83

Greasewood- -___ .____.________.______ _ _ 11

Great Basin............................ 14,22,70,83

Great Salt Lake..-........................... 9

Ground water, artesian..--.....----....-....- 39

discharge...-------....................... 45,82

infiltration galleries..-......--.......---.- 48

management- -.-....--.....--........-.-- 10

movement__ ____________________________ 44, 82

nonartesian............................... 10

pumping.-.-......--..._.--......-.._..-. 22

recharge--.......-...---....---.-....--.-- 41

reservoir ....................... 2,39,65,80,82

underflow.-.........-_-_....-._.....-. 44,48,49

H

Hardness, surface water. 

Hay....................

................ 72

.--.---.___---.. 10

Henderson Reservoir................ 38,51,53,72,81

Hydrology, quantitative........---.-..-.--.. %7

Hydrometeorology........................... 18

Introduction- ................................ %

Investigations, previous.-.................... 3

Irrigation--..... _------..-_-----_-_-.-.--._-_ 2,9

JuniperLake Bonneville-............................. 38

Lake Bonneville Group...-..__.......- -__ 38,39

Land pans, class A.--_._ _____ -_.__ _-__ 30

Langbein's method, water yield-............. 32, 50

Lapse rate-.------__...-..... .....- ... 16,66

Limestone formations, Blue Spring Hills- - - - - 3

Little Malad River............. 7,47,51,77,81,83,84

reservoir_.............................. 10

potential............................. 64

Little Malad River above Elkhorn Reservoir 

(Dam), near Malad City, gaging 

station-.......................... 51,66

Location and extent of area................... 3

Long Island, N.Y., evapotranspiration.------ 34

stream temperatures. -............... _ 76

Low-flow characteristics, streams...-......--. 53

M

Madison LimestonePage 

Malad City............. 2,3,6,10, 14,22,38,39,41,82

precipitation...__................... 20,24,66

water supply............................. 48

Malad City Airport, precipitation............ 66

temperature.-............................ 14

Malad Range...-_.......................... 3,7,38

Malad River, drainage area...---_........... 3

reservoir-_....._...................... 81

source.................................... 7

temperature.............................. 76

Malad River at Cherry Creek Lane, gaging

station........................... 72

Malad River at Woodruff, gaging station..... 45,

49,50, 51, 56, 65, 72,75,81 

Malad River below springs, near Malad City,

gaging station...__________.___.__ 56

Malad Valley..------_.-_--..--.-.-.-. 3,32,39,76

acreage irrigated-...--....--.---.......... 50

alluvial fans-..._........................... 43

flood of 1962.............................. 66

ground-water reservoir.----- -_._-- - 65,80

population............................... 6

topography and drainage................. 7

Marsh reedgrass----------.......--.....-.... 11

Moisture barriers.----_.----_-----_---.- ---- 12,24

Monroe Canyon Limestone------.-------.-.- 38

Mount Elkhorn-.__-__....-. .......-..-.. 7

Mower, R. W., written communication ._ 38

O 

Ogden, Utah............ ................... 6

Oneida County__........-..---...-..-..-.. 3,6

Oregon, stream temperatures. --....... ..--- 76

Oxford Peak................................ 7

Perched water..... 

Perennial streams. 

Phreatophytes- - - - 

Pickleweed----.-.. 

Fine -------

.....-.........- . 39

. ___.-. _ 83 

...-....-...--- ... 11

.-----.-.-----.-...... 11

.---.._ -.-.. - 11 

Pleasantview.-.............................. 7,41

Pocatello-------------------------------- 3,20,24

Population, Malad Valley.........._------ 6

Portneuf River at Topaz Statton, gaging

station----.----...-------.-----. 35

Potatoes ...... .......................... 10

Power County.. ........................... 3

Precipitation, areal distribution_........... &7

eflective....................--- ..------. 50

intensity-................................ #4

Malad City.---..-..-.---.-------.--. 20,24,66

Malad City Airport-.--...,-------------- 66

mean annual....-..--.---------------..-. 30,38

relation to altitude-.-----.-------. -- - 28

seasonal distribution.---...............-- $4

Provo shoreline ........-....-.----..-.-.-.- 38

Pumping, ground water------.------.-------- 22

Purpose of report-..........-.....--.....-.--- 3

R

Rabbitbrush-...---. -.--................. 11

Rainfall. See Precipitation.

Recurrence interval, formula................. 68

Relief, Malad Valley___....._........... 7
INDEX 89

Page 

Reservoirs..................... 10,38,51,53,64,72,81

Rocky Mountains...--....-...-.-..---....-.. 18

Rushes....................................... 11

Sagebrush..........

St. Johns Canal..-. 

Salinization of soilsSalt-...............

Salt Lake City, Utah......................... 3,(

Salt Lake FonnationSamaria Reservoir....

Scrub maple...__... 

Scrub oak............

Sedge -..-----....

_......-..-....... 38

.................. 81

.................. 11

.................. 11

................... 11

Sheep..-..........-.-.-..-..-.----------.--.. 10

Snake River basin............................ 10

Soda Springs. ............................. 6

Springs. ........................... 7,45,76,82,83

Spruce _. _.. - . 11

Stone-fruit trees...-..-.-.--.-.---.-_------... 75

Streams. See Surface water.

Sugar beets................................... 10,32

Summary and conclusions -----_.-.-----_. 8i

Surface water.. ........................... 61

days of deficient discharge................ 61

dissolved-solids content .---.--.-----_.- 72

droughts.-...-...--.-.-..----------.--.-_ 22

ephemeral streams-. .................. 7,83

floods.-----.....-.........-.......-.. .. 65

flow-duration curves.-------- . - 58

frequency-mass curves_.........-.. .. 62

grain-size distribution--.-. . _ - 78

hardness-.------.-,-..---.------.-- 72

low-flow characteristics.. ..-.----------. 55

low-flow frequency curves.-.._____- _. 60

management- ___.._.____.____.__ _. ___ 10

monthly discharge summary.-.......,._. 55

perennial streams .....----..- -.-..--. 83

quality. ----___ ---. --.- -- -- 71

salinity hazard--.....------ .- - -- 75

---------- 48,83

Surface water Continued Page 

sodium hazard. --... ................... 75

storage-required frequency. ........... 6t

temperature. ............................. 76,S3

Temperature, air...... ---. ... ....... 14

water....--.----.-----------------.-- 75,83

Thornthwaite's method, evapotranspiration. - 32,50 

Thunderstorms. ___ __.-. - -- -- 24

Topography and drainage.----.------------- 7

U 

Underflow.. . - --- - 44,48,49

Vegetation.-.-.... .- -- -. . 11

W 

Warm Springs Canal.... - --- . ..... 50

Wasatch Mountains...._ _ _ _ 27

Water loss, estimates....-- .. ..--..-. --- 30,34

equation- ----...__ - - ----- 31

Water management-_--_ . 80

Water yield-.--..---.----------------- Si

above Woodruff--.....-....-..-..- ..-.- 51

annual.................. .. --...--.... 50

equation...... .............. .... ... 32

evaluation. ---- - --.. --.--. 27

Langbein's method....................... 32,50

mean...........-..------------........... 35

Weather stations........----..- ..--.---.... 27

Well-numbering system.._ __-_-_ __._-_ _ 5 

Wells, artesian---.----------------- 3,82

flowing-................. .--..-....-.. 10

Wells stratigraphic unit...--....---..------. 38

Wheat..--...- .-- -- - 10,20 

Willow Creek near Ririe, gaging station...... 35

Wirerush- .- 11

Woodruff.. -.--..-------------.-.- 3,7,30,35

Woodruff fault.... -.- ----- 3,39,45

Woodruff Springs....... ..-. . ...... 45,72

Wright Creek-....----...-.-.. --- 9,78,84