U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2010–5205

Revised November 2010

In cooperation with the Village of Ruidoso, New Mexico

Hydrology of Eagle Creek Basin and Effects of Groundwater 

Pumping on Streamflow, 1969–2009
Cover left. Eagle Creek below South Fork near Alto, New Mexico, gage (08387600). Picture taken May 30, 2006, by Nathan Myers.

Cover right. Eagle Creek below South Fork near Alto, New Mexico, gage (08387600). Picture taken September 28, 2006, by Nathan Myers.
In cooperation with the Village of Ruidoso, New Mexico

Scientific Investigations Report 2010–5205

Revised November 2010

U.S. Department of the Interior

U.S. Geological Survey

Hydrology of Eagle Creek Basin and Effects 

of Groundwater Pumping on Streamflow, 

1969–2009

By Anne Marie Matherne, Nathan C. Myers, and Kurt J. McCoy
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

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

Revised: November 2010

This and other USGS information products are available at http://store.usgs.gov/

U.S. Geological Survey

Box 25286, Denver Federal Center

Denver, CO 80225

To learn about the USGS and its information products visit http://www.usgs.gov/

1-888-ASK-USGS

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

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

reproduce any copyrighted materials contained within this report.

Suggested citation:

Matherne, A.M., Myers, N.C., and McCoy, K.J., 2010, Hydrology of Eagle Creek Basin and effects of groundwater 

pumping on streamflow, 1969–2009: U.S. Geological Survey Scientific Investigations Report 2010–5205, 73 p. 

(Revised November 2010)
iii

Acknowledgments

This study was conducted with the cooperation of the Village of Ruidoso, New Mexico. 

Special thanks are given to the Village of Ruidoso Water and Wastewater Department, the U.S. 

Department of Agriculture, Forest Service Smokey Bear Ranger District, and the Eagle Creek 

Conservation Association. We would also like to thank the New Mexico Geological Society for 

permission to adapt a figure from the 1964 New Mexico Geological Society Guidebook.
iv

Contents

Acknowledgments........................................................................................................................................iii

Conversion Factors........................................................................................................................................v

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

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

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

Physical Description of Eagle Creek Basin .....................................................................................2

Regional Setting....................................................................................................................................2

Previous Investigations........................................................................................................................7

Methods...........................................................................................................................................................7

Surface-Water Measurements ..........................................................................................................7

Groundwater Measurements .............................................................................................................8

Water Chemistry Measurements .......................................................................................................9

Hydrology of the Eagle Creek Basin Study Area ......................................................................................9

Hydrologic Setting ................................................................................................................................9

Precipitation..................................................................................................................................9

Surface Water............................................................................................................................14

Groundwater...............................................................................................................................14

Long-Term Water Balance ................................................................................................................14

Base Flow and Direct Runoff ...................................................................................................14

Precipitation................................................................................................................................14

Evapotranspiration ....................................................................................................................18

Basin Yield...................................................................................................................................24

Groundwater Recharge ............................................................................................................24

Basin Yield Method...........................................................................................................24

Chloride Mass-Balance Method....................................................................................24

Groundwater Discharge Out of the Basin .............................................................................27

Hydrology of North Fork Eagle Creek .......................................................................................................27

Groundwater........................................................................................................................................27

Borehole Logs.............................................................................................................................27

Groundwater Levels ..................................................................................................................31

Alluvial Wells .....................................................................................................................31

Bedrock Wells ...................................................................................................................32

North Fork Eagle Creek Groundwater Response .................................................................37

Chemical Composition of Surface Water and Groundwater in Eagle Creek Basin.................39

Major-Ion Chemistry..................................................................................................................39

Stable Isotopes ..........................................................................................................................39

Chlorofluorocarbons ................................................................................................................43

Patterns of Surface-Water and Groundwater Chemistry ...................................................45

Surface Water.....................................................................................................................................47

Long-Term Discharge Patterns at Eagle Creek Gaging Station.........................................47

Factors Affecting Eagle Creek Discharge .............................................................................51

Patterns of Discharge Within Eagle Creek Basin.................................................................51

Streamflow Loss in North Fork Eagle Creek..........................................................................54

Conceptual Model of North Fork Eagle Creek Hydrology ............................................................54
v

Effects of Groundwater Pumping on Streamflow...................................................................................56

Discharge Required To Sustain Continuous Flow in North Fork Eagle Creek...........................56

Effects of Pumping on Continuous Flow in North Fork Eagle Creek...........................................57

Summary........................................................................................................................................................61

References Cited..........................................................................................................................................64

Appendix 1. Well-completion details for monitoring wells MW-1A, MW-1B, 

MW-1C, MW-2A, MW-3A, MW-4B, MW-4C, and MW-5A near North 

Fork Eagle Creek, New Mexico....................................................................................................68

Figures

1. Location of study area and geographic features in south-central 

New Mexico ........................................................................................................................3

2. North and South Fork Eagle Creek Basins, gaging stations, and 

wells in south-central New Mexico .................................................................................4

3. A, Ruidoso, New Mexico, climate station annual, 5-year moving 

average, and mean annual precipitation, 1942–2008. 

B, Ruidoso, New Mexico, climate station mean monthly 

precipitation and percent of mean annual precipitation, 1942–2008, 

and Sierra Blanca, New Mexico, climate station mean monthly 

precipitation and percent of mean annual precipitation, 2003–8 ................................5

4. Generalized geologic and structural features of the region near the 

Eagle Creek Basin study area in south-central New Mexico .....................................6

5. Base-flow analysis for the Eagle Creek gaging station (08387600) in 

south-central New Mexico, August 27, 1969, to December 31, 2008. 

A, The average mean daily reported discharge. B, The average 

mean daily base flow from base-flow analysis ............................................................15

6. Relation of mean annual precipitation and elevation for climate 

stations in the Sacramento, Sierra Blanca, and Capitan Mountain 

areas, New Mexico ...........................................................................................................17

7. Elevation bands used in water-balance calculations for the Eagle 

Creek Basin above the Eagle Creek gaging station (08387600) in 

south-central New Mexico ..............................................................................................19

8. Borehole geophysical logs for North Fork Eagle Creek borehole 

MW-1, May 22, 2007, south-central New Mexico........................................................29

9. Borehole geophysical logs for North Fork Eagle Creek borehole 

MW-4, February 18, 2008, south-central New Mexico................................................30

10. Schmidt lower hemisphere equal-area stereoplot showing 

orientation of fractures from MW-4 borehole, North Fork Eagle 

Creek, New Mexico...........................................................................................................31

11. Histogram of fracture dips from MW-4 borehole, North Fork 

Eagle Creek, New Mexico................................................................................................32

12. Daily mean surface-water discharge and temperature at the North 

Fork Eagle Creek gaging station (08387550) in south-central New 

Mexico and hourly groundwater elevation and temperature in 

shallow (alluvial) wells (MW-1A, MW-2A, MW-3A, MW-5A) ...................................33

13. Effect of late November to early December 2007 discharge 

event at the North Fork Eagle Creek gaging station (08387550), 

south-central New Mexico, on water temperature in alluvial 

wells (MW-1A, MW-2A, MW-3A, MW-5A)....................................................................34
vi

14. A, Daily water-level elevation in monitoring wells MW-1B 

and MW-1C and pumping from NF-1 production well. B, Daily 

precipitation at Ruidoso, New Mexico, climate station..............................................35

15. A, Daily water-level elevation in monitoring wells MW-4B and 

MW-4C and pumping from NF-4 production well. B, Daily precipitation 

at Ruidoso, New Mexico, climate station......................................................................36

16. Longitudinal profile of North Fork Eagle Creek, New Mexico, 

showing relative location and depth of monitoring, production, 

and domestic wells and water levels in alluvium and bedrock on 

September 3, 2008, and March 17, 2009.........................................................................38

17. Trilinear diagram showing hydrochemical-facies classification of 

major-ion chemistry of surface water and groundwater in Eagle 

Creek Basin, New Mexico, sampled in June, September, and 

December 2008 and March 2009.....................................................................................40

18. Concentrations of selected constituents in surface-water and 

groundwater samples from Eagle Creek Basin, New Mexico, 

sampled in June, September, and December 2008 and March 2009. 

A, Calcium and sulfate. B, Calcium and bicarbonate. C, Sodium 

and chloride........................................................................................................................41

19. Stable isotopes deuterium and oxygen-18 expressed as 

the deviation from Standard Mean Ocean Water in surfacewater and groundwater samples, North Fork Eagle Creek, 

New Mexico, June 2008 to March 2009. A, Data grouped by 

time of sample collection. B, Data grouped by sample site .......................................42

20. Trends of chemical constituents in surface-water and groundwater 

samples from North Fork Eagle Creek, New Mexico, and groupings 

based on significant differences in constituent concentrations...............................46

21. Precipitation and stream discharge for the period August 28, 1969, 

to December 31, 2008, in the Eagle Creek Basin, New Mexico. 

A, Monthly precipitation at Ruidoso, New Mexico, climate station. 

B, Daily mean discharge at the Eagle Creek gaging station (08387600). 

C, Monthly no-flow days at the Eagle Creek gaging station (08387600)...................48

22. Median annual and median monthly discharge at the Eagle Creek 

gaging station (08387600), in south-central New Mexico, for the 

periods A, 1970–79 and B, 1989–2008 .............................................................................49

23. Exceedance probability of discharge at the Eagle Creek gaging 

station (08387600), in south-central New Mexico, for the periods 

1970–79 and 1989–2008 and for the years of maximum (1979) and 

minimum (2002) annual discharge for the period of record........................................50

24. Regression relations between annual precipitation by water year at 

Ruidoso, New Mexico, climate station and annual discharge by water 

year at the Eagle Creek gaging station (08387600), in south-central New 

Mexico, for water years 1970–79 and 1989–2008 .........................................................52

25. Monthly discharge at the Eagle Creek gaging station (08387600), the 

North Fork gaging station (08387550), the South Fork gaging station 

(08387575), and the sum of the discharges of the North Fork and 

South Fork, south-central New Mexico.........................................................................53

26. Flowing and nonflowing reaches of North Fork Eagle Creek, New 

Mexico, May 7, 2007..........................................................................................................55
vii

27. Distance downstream from North Fork Eagle Creek gaging station 

(08387550), New Mexico, at which water disappears from the stream 

channel, and mean daily discharge at the gaging station for the dates 

of measurement.................................................................................................................56

28. Delineation of valley widths between the North Fork gaging station 

and the Eagle Creek gaging station, indicating alluvial fill in North 

Fork Eagle Creek Valley, south-central New Mexico ..................................................58

29. Magnitude of discharge needed to saturate the alluvium of North Fork 

Eagle Creek, south-central New Mexico, from top of bedrock to bottom 

of stream channel..............................................................................................................59

30. Exceedance probability of discharge at North Fork Eagle Creek gaging 

station (08387550), south-central New Mexico, for September 2007 to 

March 2009 .........................................................................................................................60

Tables

1. Details of placement and construction of monitoring and production 

wells and descriptions of surface-water sampling sites along North 

Fork Eagle Creek, New Mexico .........................................................................................8

2. Annual and mean precipitation and station elevation for climate 

stations in the Upper Rio Hondo Basin, south-central New Mexico........................10

3. Results of base-flow analysis of discharge data from the Eagle Creek 

gaging station (08387600) in south-central New Mexico, August 27, 1969, 

to December 31, 2008 ........................................................................................................16

4. Mean annual measured discharge, direct runoff, and base flow for the 

Eagle Creek gaging station (08387600) in south-central New Mexico, 

1970–80 and 1989–2008 .....................................................................................................17

5. Estimated mean annual precipitation for the elevation bands in the Eagle 

Creek Basin, New Mexico................................................................................................20

6. Estimated mean annual evapotranspiration for elevation bands in the 

Eagle Creek Basin, New Mexico.....................................................................................21

7. Mean monthly minimum and maximum temperatures and elevations for 

selected climate stations in south-central New Mexico and regression 

equations relating temperature to elevation.................................................................23

8. Estimated annual Eagle Creek Basin yield and basin-yield error .............................25

9. Basin-yield water-balance components using 1910–2008 mean annual 

precipitation; 1970–80 mean annual discharge, direct runoff, and base 

flow; and 1970–80 and 1988–2008 North Fork well pumpage .....................................26

10. Estimates of groundwater recharge using the chloride mass-balance 

approach for Eagle Creek Basin upstream from the Eagle Creek below 

South Fork near Alto, New Mexico, gaging station (08387600)..................................28

11. Summary of properties that can modify apparent age determined by 

chlorofluorocarbon analysis............................................................................................44
viii

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 4,047 square meter (m2

)

acre 0.4047 hectare (ha)

acre 0.4047 square hectometer (hm2

) 

acre 0.004047 square kilometer (km2

)

square mile (mi2) 259.0 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2) 

Volume

acre-foot (acre-ft) 1,233 cubic meter (m3

)

acre-foot (acre-ft) 0.001233 cubic hectometer (hm3

) 

Flow rate

acre-foot per day (acre-ft/d) 0.01427 cubic meter per second (m3

/s)

acre-foot per year (acre-ft/yr) 1,233 cubic meter per year (m3

/yr)

acre-foot per year (acre-ft/yr) 0.001233 cubic hectometer per year (hm3

/yr)

cubic foot per second (ft3/s)

gallon per minute (gal/min)

 0.02832

0.06309

cubic meter per second (m3/s)

liter per second (L/s)

Hydraulic conductivity

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

Hydraulic gradient

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

Transmissivity

foot squared per day (ft2/d) 0.09290 meter squared per day (m2/d) 

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

°F=(1.8×°C)+32

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

°C=(°F-32)/1.8

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88), except in some cases to the National Geodetic Vertical Datum of 1929 (NGVD 29).

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

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

25°C).

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

or micrograms per liter (μg/L).
Hydrology of Eagle Creek Basin and Effects of 

Groundwater Pumping on Streamflow, 1969–2009

By Anne Marie Matherne, Nathan C. Myers, and Kurt J. McCoy

Abstract

Urban and resort development and drought conditions 

have placed increasing demands on the surface-water and 

groundwater resources of the Eagle Creek Basin, in southcentral New Mexico. The Village of Ruidoso, New Mexico, 

obtains 60–70 percent of its water from the Eagle Creek 

Basin. The village drilled four production wells on Forest 

Service land along North Fork Eagle Creek; three of the four 

wells were put into service in 1988 and remain in use. Local 

citizens have raised questions as to the effects of North Fork 

well pumping on flow in Eagle Creek. In response to these 

concerns, the U.S. Geological Survey, in cooperation with the 

Village of Ruidoso, conducted a hydrologic investigation from 

2007 through 2009 of the potential effect of the North Fork 

well field on streamflow in North Fork Eagle Creek. 

 Mean annual precipitation for the period of record 

(1942–2008) at the Ruidoso climate station is 22.21 inches per 

year with a range from 12.27 inches in 1970 to 34.81 inches 

in 1965. Base-flow analysis indicates that the 1970–80 mean 

annual discharge, direct runoff, and base flow were 2,260, 

1,440, and 819 acre-ft/yr, respectively, and for 1989–2008 

were 1,290, 871, and 417 acre-ft/yr, respectively. These results 

indicate that mean annual discharge, direct runoff, and base 

flow were less during the 1989–2008 period than during the 

1970–80 period. 

Mean annual precipitation volume for the study area 

was estimated to be 12,200 acre-feet. Estimated annual 

evapotranspiration for the study area ranged from 8,730 to 

8,890 acre-feet. 

Estimated annual basin yield for the study area was 3,390 

acre-ft or about 28 percent of precipitation. On the basis of 

basin-yield computations, annual recharge was estimated to 

be 1,950 acre-ft, about 16 percent of precipitation. Using a 

chloride mass-balance method, groundwater recharge over 

the study area was estimated to average 490 acre-ft, about 4.0 

percent of precipitation. 

Because the North Fork wells began pumping in 1988, 

1969–80 represents the pre-groundwater-pumping period, and 

1988–2009 represents the groundwater-pumping period. The 

5-year moving average for precipitation at the Ruidoso climate 

station shows years of below-average precipitation during both 

time periods, but no days of zero flow were recorded for the 

11-year period 1970–80 and no-flow days were recorded in 11 

of 20 years for the 1988–2009 period. 

Results of a Mann-Whitney statistical test indicate that 

the median annual discharge is not significantly different 

between the periods 1970–79 and 1989–2008. Monthly 

medians for the two periods, however, indicate a shift in the 

pattern of runoff from snowmelt to monsoon-dominated flow. 

The 1970–79 and 1989–2008 exceedance curves are similar 

at the highest discharge values but diverge for the remainder 

of the record, with 1970–79 discharge being greater than 

1989–2008 discharge for a given probability of occurrence. 

The 1989–2008 exceedance curve declines more rapidly than 

does the 1970–79 curve, reflecting less available sustained 

base flow than for the earlier period. 

Variation in the location of the end of perennial flow, 

expressed as distance downstream from the North Fork 

gaging station, was compared to daily average discharge at 

the gaging station on the date of the survey. The few data 

available indicate that streamflow infiltrates into bedrock in 

the streambed about 1,600 ft downstream from the North Fork 

gaging station, where it is available to recharge the bedrock 

aquifer. The streambed in this reach appears to have a capacity 

to transmit water at a threshold rate of about 0.7–1 ft3/s. The 

amount of water needed to saturate the alluvium to the bottom 

of the stream channel at its greatest cross-sectional area 

between the North Fork and Eagle Creek gages was estimated 

using Darcy’s law to range from 0.6 ft3/s to 1.2 ft3/s. The 

observed coarse nature of the alluvium would indicate that 

the actual hydraulic conductivity is likely nearer the higher 

range of hydraulic conductivity values, requiring a discharge 

of 1.2 ft3/s to saturate the alluvium to the bottom of the stream 

channel. Sustained flows greater than 2.2 ft3/s (threshold rate 

of 1.0 plus 1.2 ft3/s) are needed to saturate the alluvium and 

maintain continuous flow in the North Fork. In the 19-month 

period of record from September 2007 through March 2009, 

2.2 ft3/s of discharge was equaled or exceeded at the North 

Fork gaging station 2 percent of the time. 

If it is assumed that, without pumping, the bedrock 

aquifer would be saturated to the base of the alluvium, then 

a discharge of only 1.2 ft3/s required to saturate the alluvium 

in its thickest and widest reach would be needed to sustain 

continuous flow in the stream. During the study period, a 

discharge of 1.2 ft3/s was equaled or exceeded at the North 
2 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

Fork gaging station 8 percent of the time. Based on the 

discharge record at the Eagle Creek gage, given alluvium and 

channel configurations similar to those described in this study, 

streamflow in some part of the stream channel between the 

North Fork and Eagle Creek gages was likely discontinuous 

during part of the year during both time periods.

Introduction

In recent years, urban and resort development and 

drought conditions have placed increasing demands on the 

surface-water and groundwater resources of the Eagle Creek 

Basin, located on the eastern flank of the Sierra Blanca 

in south-central New Mexico (figs. 1 and 2). As a result, 

communities and residents in the area are concerned about 

potential and, in some cases, actual water shortages. 

The Village of Ruidoso, New Mexico, obtains 60–70 

percent of its water from the Eagle Creek Basin (Ken Mosley, 

oral commun., 2007) (figs. 1 and 2). In 1985, the U.S. 

Department of Agriculture, Forest Service (Forest Service) 

issued a special-use permit to allow the Village of Ruidoso to 

drill production wells on and lay water pipeline across Forest 

Service land (Richard Carlson, oral commun., 2006). The 

village drilled four production wells (the North Fork wells, 

which make up the North Fork well field) on Forest Service 

land along North Fork Eagle Creek (hereafter referred to as 

the “North Fork”) (fig. 2). Well depths ranged from 599 to 

about 800 feet (ft) below land surface; some of the wells were 

later deepened and currently (2009) range in depth from 785 

to 1,000 ft below land surface (Finch and others, 2004). Three 

of the four wells (NF-1, NF-3, and NF-4, fig. 2) were put into 

service in 1988 and remain in use. Well NF-2 was used to 

monitor water levels but is now sealed.

Local citizens have raised questions as to the effects of 

North Fork well pumping on flow in Eagle Creek. In response 

to these concerns, the U.S. Geological Survey (USGS), 

in cooperation with the Village of Ruidoso, conducted a 

hydrologic investigation from 2007 through 2009 in relation to 

the potential effect of the North Fork well field on streamflow 

in the North Fork. 

Purpose and Scope

This report describes the hydrology of the Eagle Creek 

Basin above the USGS streamflow-gaging station Eagle Creek 

below South Fork near Alto, New Mexico (USGS gage no. 

08387600; hereafter referred to as the “Eagle Creek gaging 

station”), with an emphasis on the North Fork in the vicinity of 

the North Fork well field, and effects of groundwater pumping 

on streamflow. A long-term water balance is constructed 

for the study area to provide estimates of the volume of 

groundwater and surface water discharging from the basin. 

Results of field studies conducted during 2007 through 2009 

are reported and discussed with respect to the potential 

interaction of groundwater and surface water with pumping 

from the North Fork wells. Fluctuations in groundwater levels 

in the area adjacent to the North Fork wells and seasonal 

water-quality data are incorporated with the streamflow 

record to develop a conceptual model of surface-water and 

groundwater hydrology for Eagle Creek Basin. Long-term 

discharge records from the Eagle Creek gaging station are 

used to examine discharge patterns at Eagle Creek before 

and after installation of the North Fork wells. The discharge 

required to sustain continuous flow and the potential effects of 

pumping on streamflow in the North Fork are discussed.

Physical Description of Eagle Creek Basin 

The study area (Eagle Creek Basin upstream from the 

Eagle Creek gaging station) is located on the eastern flank of 

the Sierra Blanca within the Upper Rio Hondo Basin (fig. 1) 

and about 2.5 miles (mi) west of Alto, New Mexico. Eagle 

Creek (fig. 2) has a drainage area of 8.1 square miles (mi2) 

above the Eagle Creek gaging station and consists of the North 

Fork Eagle Creek (“North Fork”) Basin (5.3 mi2) and the 

South Fork Eagle Creek (“South Fork”) Basin (2.8 mi2). The 

North Fork well field lies within the North Fork Basin (fig. 2).

The North Fork has a narrow, steep drainage. The head of 

the drainage lies at about 10,500 ft elevation. The main valley 

is characterized by forested hill slopes and is dissected by side 

drainages with elevation differences of about 1,300 ft between 

the ridge tops and the streambed. The Eagle Creek gage, at the 

mouth of Eagle Creek Basin, lies at an elevation of 7,600 ft. 

Longitudinally, the elevation of the drainage between the head 

and the gage declines 2,900 ft in 4.5 mi, giving the stream an 

average slope of 640 feet per mile (ft/mi). 

In the study area, the Eagle Creek Basin is forested, 

primarily by ponderosa pine (Pinus ponderosa) and mixed 

conifers (U.S. Forest Service, written commun., 2007). 

Precipitation in the area, as measured at the Ruidoso climate 

station, averaged 22.21 inches per year (in/yr) for the period 

of record, from 1942 through 2008 (fig. 3A), and consisted 

mainly of winter snow and summer monsoonal rains (fig. 3B). 

On average, 65 percent of the annual precipitation falls as 

monsoonal rains from June through October, with 35 percent 

of the annual precipitation during the months of July and 

August (fig. 3B).

Although most of the study area upstream from the North 

Fork well field is undeveloped, a group of 22 cabins is located 

along Eagle Creek above the area instrumented for this study. 

The cabins are occupied seasonally and obtain groundwater 

from shallow (about 100 ft deep) wells. 

Regional Setting

The Upper Rio Hondo Basin is bounded on the west 

by the Sacramento Mountains and Sierra Blanca and on 

the north by the Capitan Mountains (fig. 1). The cores of 

these mountain ranges are composed primarily of igneous 
Introduction 3

U.S. 82

U.S. 380

U.S. 70

N.M. 246

N.M. 368

N.M. 48

N.M. 244

N.M. 37

N.M. 130

U.S. 54

N.M. 214

N.M. 130

U.S. 70 

U.S. 380

Alto

Nogal 

Hondo 

Ruidoso 

Picacho 

Mayhill 

Lincoln 

Capitan 

Encinoso 

Whitetail 

Carrizozo 

Cloudcroft 

Fort Stanton 

Mountain Park 

Silver Springs 

Mountain Park 

Mountain Park 

Climate station and name

Village or town and name

EXPLANATION

Trace of geologic section shown in figure 4

Ruidoso Picacho 

Capitan 

Whitetail 

Cloudcroft 

Mescal 

Sierra Fort Stanton 

Blanca

Peak

Mountain Park 

Mayhill Ranger Station

SIERRA BLANCA

Sierra

Blanca

S A C R A M E N T O

M O U N TA I N S

CAPITAN MOUNTAINS

R i o R u i d o s o

R i o B o n i t o

E a g l e

R i o H o n d o

C r e e k

0 5 10 MILES

0 5 10 KILOMETERS

105°40' 105°20'

33°40'

33°20'

33°00'

Study area

(Eagle Creek Basin 

above the Eagle Creek

below South Fork

gaging station)

Boundary of

Upper Rio Hondo Basin

Approximate

line of 

section 

shown in 

figure 4

A A ́

Base from New Mexico Geospatial Data Acquisition Coordination Committee, 2006, 1:12,000

Universal Transverse Mercator projection 

Zone 13

NEW MEXICO

Map Area

Albuquerque

Roswell

A A ́

Figure 1. Location of study area and geographic features in south-central New Mexico. 
4 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

Forest Road 127A

North Fork

well field

North ForkEagle Creeknear Alto, N. Mex.(08387550)

Johnson Canyon

Carlton Canyon

MW-1B, 1C

MW-5A

MW-4B, 4C

MW-3A

MW-2A

NF-3

NF-2

MW-1A

NF-1

NF-4

Eagle Lake No. 1

Eagle Lake No. 2

FOREST ROAD 127A

COUNTY ROAD 532 Boundary of South Fork 

Eagle Creek Basin

Boundary of North Fork 

Eagle Creek Basin

COUNTY ROAD 532

elephone Canyon T

Eagle Creek belowSouth Fork near Alto, N. Mex.(08387600)

South ForkEagle Creeknear Alto, N. Mex.(08387575)

South Fork

Eagle Creek

Eagle Creek

North Fork

Eagle Creek

105°47' 105°46' 105°45' 105°44' 105°43'

33°25'33°24'33°23'

North Fork

Eagle Creek

0 1 0.5 MILE

0 1 0.5 KILOMETER

Base from New Mexico Geospatial Data Acquisition Coordination Committee, 2006, 1:12,000Universal Transverse Mercator projection Zone 13 

Eagle Creek contributing area between confluence of North and South Forks of Eagle Creek and the Eagle Creek below South Fork 

near Alto, N. Mex., gaging station

DW-1

DW-2

DW-3

EXPLANATION

North Fork production well and number

NF-4

Monitoring well and number MW-5A

Streamflow-gaging stationand number

South ForkEagle Creeknear Alto, N. Mex.(08387575)

Domestic well and number DW-1

Figure 2. North and South Fork Eagle Creek Basins, gaging stations, and wells in south-central New Mexico.
Introduction 5

5.80

8.48

4.66 4.87 4.56

5.93

17.57 17.73

9.56

7.64

5.45

7.75

5.26 5.22 4.95

3.31

4.54

8.76

18.74

19.74

11.52

6.72

3.81

7.43

0

1

2

3

4

5

6

7

8

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

PRECIPITATION, IN INCHES

Sierra Blanca SNOTEL climate

station and percent of mean

annual precipitation

Ruidoso climate station

and percent of mean

annual precipitation

B

5

10

15

20

25

30

35

40

1940 1950 1960 1970 1980 1990 2000 2010

Annual precipitation

5-year moving average

PRECIPITATION, IN INCHES

A

Mean: 22.21 inches

EXPLANATION

Figure 3. A, Ruidoso, New Mexico, climate station annual, 5-year moving average, and mean annual precipitation, 1942–2008. Years 

missing 6 or more days of data from 1 or more months during a year are not included. B, Ruidoso, New Mexico, climate station mean 

monthly precipitation (in inches) and percent (shown as numbers above and within the bars) of mean annual precipitation, 1942–2008, 

and Sierra Blanca, New Mexico, climate station mean monthly precipitation (in inches) and percent (shown as numbers above and 

within the bars) of mean annual precipitation, 2003–8.
6 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

intrusive and volcanic rocks of Tertiary age. The study area 

lies within the bounds of the Sierra Blanca structural basin 

(fig. 4), a downfold of sedimentary rocks of Permian and 

Cretaceous ages that are overlain by as much as 3,000 ft of 

Tertiary volcanic flows and breccias (volcaniclastics) (Allen 

and Kottlowski, 1981). The Three Rivers stock, a granitic 

intrusion, cuts through the Permian and Cretaceous rocks and 

forms the high-altitude crest of Sierra Blanca (fig. 4). The 

rocks exposed at land surface within the study area consist of 

volcaniclastic and intrusive rock.

Important water-bearing units within the Upper Rio 

Hondo Basin include the volcaniclastics of Tertiary age, 

the Dakota Sandstone of Cretaceous age, and San Andres 

Limestone and Yeso Formation of Permian age (Thompson, 

1964). The volcaniclastics consist primarily of alternating 

layers of gray to dark green andesite porphyry and andesite 

breccia (Thompson, 1964). The North Fork wells obtain their 

water from the volcaniclastics (Newcomer and Shomaker, 

1991). Wells completed in the Dakota Sandstone near the 

Ruidoso fault zone have yielded water at rates of more than 

100 gallons per minute (gal/min) (Newcomer and Shomaker, 

1991). East of the Ruidoso fault zone, the primary aquifers 

are the San Andres Limestone and the Yeso Formation. Yields 

from wells completed in the San Andres Limestone range 

from 10 to 1,000 gal/min (Mourant, 1963), whereas the Yeso 

Formation generally yields smaller quantities of water to wells 

(Newcomer and Shomaker, 1991). 

The Ruidoso fault zone (fig. 4) is a series of northnortheast trending offsets in the Cretaceous, Permian, and 

Precambrian units that mark the eastern boundary of the 

Sierra Blanca structural basin (Kelley and Thompson, 1964). 

Along this boundary the permeable San Andres Formation 

dips or is downfaulted into the Sierra Blanca structural basin. 

The geologic structure of the area is complex with numerous 

normal faults oriented parallel or subparallel to the regional 

bedrock strike with fault traces trending approximately north 

20 degrees (o) east (Green and Jones, 1997; Rawling, 2008). 

Cross-strike longitudinal and oblique faults also occur with 

traces at attitudes of between approximately north 60o west 

and north 65o east. The rocks are tectonically deformed, and 

numerous folds occur in the area and can affect groundwater 

flow. Because the bedrock underlying the study area consists 

of lithologies with low primary permeability (Newcomer 

and Shomaker, 1991), groundwater flow is dependent on 

secondary permeability produced by tectonic fracturing or 

tertiary permeability related to mineral dissolution along 

fracture zones (Newcomer and Shomaker, 1991). Bedrock 

fractures include tectonically induced faults and joints, as 

WEST EAST

Sierra

Blanca

Cretaceous

Permian

Three

Rivers

stock

Precambrian

Tertiary

volcanics Ruidoso fault zone

Cretaceous

Permian

Permian

Precambrian

?

Sierra Blanca structural basin

?

NOT TO SCALE

Approximate extent 

of Eagle Creek

Basin study area

A A ́

Figure 4. Generalized geologic and structural features of the region near the Eagle Creek Basin study area in south-central New 

Mexico. Modified with permission from Kelley and Thompson, 1964. Trace of section shown in figure 1. 
Methods 7

well as partings between bedding planes. This secondary 

permeability is especially important in areas such as the 

Ruidoso fault zone, where the strike of the bedrock is 

predominantly to the north-northeast (Kelley, 1971; Green 

and Jones, 1997) but the hydrologic gradient is towards the 

confluence of the Rio Bonito and Rio Ruidoso to the eastsoutheast (Mourant, 1963; Donohoe, 2004).

Groundwater from the Sierra Blanca structural basin 

discharges to streams along the Ruidoso Fault Zone. East 

of Ruidoso, water levels in wells completed in the Yeso 

Formation are at or just below the level of streams, and 

seepage surveys indicate an increase in streamflow attributed 

to groundwater inflow (Wasiolek, 1991). More recent seepage 

surveys conducted by the USGS along the Rio Ruidoso near 

Ruidoso in February 2007 indicate that stream discharge 

increases from 9.82 to 11.70 ft3/s across the Ruidoso fault zone 

(Jack Veenhuis, U.S. Geological Survey, oral commun., 2008).

Previous Investigations

Recent hydrologic studies relevant to the North Fork 

wells and their effect on streamflow include those by Finch 

and others (2004) and Balleau (2004a). Finch and others 

(2004) reported that aquifer-test results for North Fork wells 

indicated that aquifer diffusivity was 14,000,000 feet squared 

per day (ft2/d) for well NF-1 and that transmissivities ranged 

from 1,400 to 8,294 ft2/d for wells NF-3 and NF-4. Recharge 

from fracture zones associated with Carlton Canyon and Eagle 

Creek was evident in the aquifer-test data (Finch and others, 

2004). 

In the Blaney and Criddle (1962) method, estimated 

potential evapotranspiration is subtracted from precipitation 

to determine the amount of water available for streamflow 

and groundwater recharge. Using the Blaney and Criddle 

(1962) method, Finch and others (2004) estimated basin yield 

(surface water plus groundwater outflow from the basin) for 

the Eagle Creek Basin above the Eagle Creek gaging station 

to be 2,554 acre-feet per year (acre-ft/yr; 3.53 ft3/s). This 

estimate for basin yield is consistent with the average annual 

1970–80 streamflow recorded at the Eagle Creek gaging 

station (2,259 acre-ft/yr; 3.12 ft3/s). 

Finch and others (2004) also developed a finite-difference 

groundwater-flow model for the Eagle Creek Basin. Model 

simulations indicated that the North Fork wells (pumped at a 

combined simulated rate of 627 acre-ft/yr ; 0.87 ft3/s) would 

obtain about 70 percent of their water (about 0.61 ft3/s) from 

surface water and about 30 percent (about 0.26 ft3/s) from 

groundwater storage. 

Using flow-duration curves developed by using 

streamflow recorded at the Eagle Creek gaging station from 

October 1, 1969, through September 30, 1980, Balleau 

(2004a) estimated direct runoff in the basin upstream from 

the gaging station to be 1,893 acre-ft/yr (2.61 ft3/s). Base-flow 

discharge to Eagle Creek was estimated to be 384 acre-ft/

yr (0.53 ft3/s). Balleau (2004b), using the Glover-Balmer 

equation (Glover and Balmer, 1954), estimated streamflow 

loss in Eagle Creek caused by pumping the North Fork wells 

to be 0.5 to 0.8 ft3/s. 

Methods

A water balance for the study area was developed by 

using long-term precipitation datasets and evapotranspiration 

estimated by using methods developed by MacDonald and 

Stednick (2003) and Blaney and Criddle (1962). The minimum 

aquifer recharge for the Eagle Creek Basin was estimated by 

using a chloride mass-balance method (Russell and Minor, 

2002). These methods are discussed in the “Long-Term Water 

Balance” section.

The hydrologic system of Eagle Creek was characterized 

by measurements of both groundwater levels and streamflow 

and analysis of surface-water and groundwater chemistry. 

Subsurface data also were analyzed from geophysical logs of 

the monitoring wells installed during the study.

Surface-Water Measurements

Streamflow was obtained from three gaging stations. The 

Eagle Creek gaging station (08387600) is located 2.6 mi west 

of Alto, New Mexico, on County Road 532 (figs. 1 and 2) and 

has a contributing area of 8.1 mi2. Stream stage is recorded at 

15-minute intervals and is transmitted hourly by satellite to the 

USGS National Water Information System (NWIS) database 

and Web site (http://waterdata.usgs.gov/nwis). The Eagle 

Creek gaging station had been operated during two periods, 

1969–80 and 1988 to the present (2009). A combination weir 

was added to the Eagle Creek gage in 2007. The South Fork 

Eagle Creek near Alto, New Mexico, gaging station (USGS 

gage no. 08387575; hereafter referred to as the “South Fork 

gaging station”) is located 400 ft upstream from the Eagle 

Creek gaging station (fig. 2) and has a contributing area of 2.8 

mi2. The South Fork gaging station, completed in September 

2007, consists of a 12-inch Parshall flume with a 20-ft broadcrested weir. Data are recorded at 15-minute intervals by the 

same data collection platform that serves the Eagle Creek 

gaging station. The North Fork Eagle Creek near Alto, New 

Mexico, gaging station (USGS gage no. 08387550; hereafter 

referred to as the “North Fork gaging station”) is located about 

1.6 mi above the Eagle Creek gaging station (fig. 2) and has a 

contributing area of 5.3 mi2. The gaging station was completed 

in September 2007 and consists of a compound weir, a data 

logger, and a transmitter. Data are recorded at 15-minute 

intervals and transmitted to the USGS NWIS database hourly. 

Streamflow data from the gaging stations were 

augmented by a flow-loss survey between the North Fork 

and Eagle Creek gaging stations and by repeated mapping 

of the occurrence of surface water along the North Fork. A 

longitudinal profile of surface elevation of the North Fork 

between the North Fork and Eagle Creek gaging stations was 
8 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

surveyed by using a satellite-referenced Global Positioning 

System (GPS) unit. This profile was combined with field 

surveys of locations of rock outcrops, estimates of valley 

width, and well-log descriptions of depth to bedrock to obtain 

an estimate of the volume of alluvial fill along the North Fork 

and to estimate the discharge required to sustain continuous 

flow in the North Fork.

Groundwater Measurements

Four alluvial monitoring wells (MW-1A, MW-2A, 

MW-3A, and MW-5A) and two nested bedrock monitoring 

wells (MW-1B and MW-1C; MW-4B and MW-4C) were 

installed by the USGS along the North Fork in the area of the 

North Fork well field (fig. 2) to measure groundwater. The 

alluvial wells were drilled by using a direct-rotary technique 

(Driscoll, 1986) without drilling fluid because of the shallow 

depths of the alluvial wells. The bedrock wells were drilled 

using an air-rotary technique (Driscoll, 1986), and the upper 

portion of the borehole was stabilized with surface casing. The 

wells were developed by pumping three well-volumes of fluid 

from the completed wells. MW-1A, MW-1B, and MW-1C are 

located upstream from the North Fork well field. MW-4B and 

MW-4C are located at the mouth of Carlton Canyon about 

500 ft west of well NF-4. There is no alluvial well associated 

with MW-4B and MW-4C because these wells are not located 

within the North Fork alluvium. Details of well placement are 

summarized in table 1. Appendix 1 contains well-completion 

diagrams for the alluvial and bedrock wells. The alluvial wells 

were installed at the bedrock/alluvium interface, at depths 

Table 1. Details of placement and construction of monitoring and production wells and descriptions of surface-water sampling sites 

along North Fork Eagle Creek, New Mexico.

[NAVD 88, North American Vertical Datum of 1988; NA, not applicable; NGVD 29, National Geodetic Vertical Datum of 1929]

Water-quality 

site name 

(fig. 2)

Land-surface 

elevation, 

in feet above 

NAVD 88

Description of site U.S. Geological Survey 

identification number

Borehole 

depth, in 

feet below 

land surface

Well 

depth, 

in feet 

Top and bottom 

of screen, 

in feet below 

land surface

Monitoring wells

MW-1A 7,833 Alluvial well 332413105441601 20 20 5–15

MW-1B 7,835 Shallow bedrock well 332419105441901 610 352 337–347

MW-1C 7,835 Deep bedrock well 332419105441902 610 595 580–590

MW-2A 7,799 Alluvial well 332410105441501 20.5 20.5 5–15

MW-3A 7,778 Alluvial well 332405105441201 16 16 6–16

MW-4B 7,794 Shallow bedrock well 332402105441401 802 410 390–400

MW-4C 7,794 Deep bedrock well 332402105441402 802 797 777–787

MW-5A 7,748 Alluvial well 332357105440401 14 14 4–14

Production wells

NF-1 7,811 Village of Ruidoso well 332413105441801 785 785a 150–400

NF-3 7,786 Village of Ruidoso well 332407105441501 796 796b 179–540

NF-4 7,782 Village of Ruidoso well 332402105441201 1,000 1,000c 155–451

Surface water

North Fork 7,900d Flume at North Fork Eagle Creek gage 08387550 NA NA NA

South Fork 7,630d Flume at South Fork Eagle Creek gage 08387575 NA NA NA

Carlton Canyon 7,800 Creek in Carlton Canyon near MW-4 332402105441410 NA NA NA

a

 Well completed open hole from 400 to 785 feet below land surface.

b

 Well completed open hole from 540 to 796 feet below land surface.

c

 Well completed open hole from 451 to 1,000 feet below land surface.

d

 Above NGVD 29.
Hydrology of the Eagle Creek Basin Study Area 9

ranging from 14 to 20.5 ft. MW-1B and MW-1C are screened 

at about 340 to 350 and 580 to 590 ft below land surface, 

respectively. MW-4B and MW-4C are screened at about 390 

to 400 and 780 to 790 ft below land surface, respectively. 

Changes in water level and temperature were measured 

and recorded by pressure transducers in each well at 1-hour 

intervals. Water levels in wells were measured manually on 

a periodic basis, and those measurements were used to verify 

the water levels from the pressure transducers (Freeman and 

others, 2004). MW-1B and MW-1C and the alluvial wells 

were installed in May 2007, and MW-4B and MW-4C were 

installed in February 2008.

Domestic wells were installed by cabin owners upstream 

from the North Fork gaging station in early 2008. Data from 

three of the domestic wells were used in this study. Well 

depths ranged from about 60 ft to 90 ft. Water levels in these 

wells were measured manually during site visits to supplement 

measurements from the monitoring wells.

Water Chemistry Measurements

Water samples were collected from seven of the eight 

monitoring wells, three surface-water locations, and two 

production wells to characterize the chemical composition of 

shallow and deep groundwater, surface water, and production 

water in the study area. Samples were collected June 10–11 

and 18–20, 2008, September 2–6, 2008, November 18–19, 

2008, and March 17–19, 2009. 

Samples of groundwater and surface water were collected 

and prepared for analysis according to standard USGS 

procedures (Lane and Fay, 1997; Radtke, 1997; Wilde and 

Radtke, 1998; Wilde and others, 1998a, b, c, 1999a, b; Myers 

and Wilde, 1999). Groundwater samples were collected after 

purging at least three casing volumes of water from the well or 

after field measurements of temperature, specific conductance, 

dissolved oxygen (DO), and pH had stabilized during well 

purging (Gibs and Wilde, 1999). Because of the low volume of 

surface-water discharge, surface-water samples were collected 

from a single point in the channel where the flow was confined 

and well mixed.

Water samples were analyzed for major ions, alkalinity, 

naturally stable isotopes of oxygen and hydrogen, and 

chlorofluorocarbons (CFCs). Water temperature, specific 

conductance, DO, and pH were measured at the time of 

sample collection; alkalinity values were determined in the 

field and in the laboratory by digital titration methods (Radtke 

and others, 1998). Water samples analyzed for major ions 

were filtered through a 0.45-micrometer (μm) filter and were 

acidified in the field according to standard USGS procedures 

(Radtke, 1999; Radtke and others, 1999). Standard USGS 

collection and handling procedures (U.S. Geological Survey, 

2009a, b) were used to analyze water samples for stable 

isotopes and CFCs. Chemical analyses were performed at 

the USGS National Laboratory in Denver, Colo., by using 

methods of Fishman and others (1994), at the USGS Reston 

Chlorofluorocarbon Laboratory, by using methods of U.S. 

Geological Survey (2009c), and at the USGS Reston Stable 

Isotope Laboratory, by using methods of Révész and Coplen 

(2008).

Hydrology of the Eagle Creek Basin 

Study Area

The hydrologic setting of the Eagle Creek Basin study 

area is described in the following sections in terms of the 

occurrences of precipitation, surface water, and groundwater. 

These data and additional climate data are used to develop 

a long-term water balance for the study area in terms of 

precipitation, evapotranspiration, basin yield, and groundwater 

recharge.

Hydrologic Setting

Precipitation

In the Eagle Creek Basin, climate data have been 

collected at the Sierra Blanca, New Mexico, climate station 

(fig. 1) from 2003 to the present (2009). The Sierra Blanca 

climate station is part of the SNOwpack TELemetry 

(SNOTEL) automated network that collects snowpack and 

other related climate information in the Western United States 

(Natural Resources Conservation Service, 2009). Located at 

an elevation of about 10,280 ft near the western boundary of 

the Eagle Creek Basin, the Sierra Blanca climate station is the 

highest elevation source of continuous climate record near the 

study area. Selected climate data have been collected from 

climate stations located in the Upper Rio Hondo Basin (table 

2).

The Ruidoso climate station provides the nearest longterm precipitation record from which to extrapolate climate 

information for the Eagle Creek Basin (table 2). The climate 

station is located about 4 mi southeast of the Eagle Creek 

gaging station at an elevation of 6,860 ft, 740 ft lower than 

the gaging station. A 5-year moving average of total annual 

precipitation for Ruidoso climate station data was determined 

for the 1942–2008 period of record (fig. 3A). The results 

indicate a period of mostly below-normal precipitation from 

1946 to 1975, above-normal precipitation from 1976 to 1998, 

below-normal conditions again from 2000 to 2006, and a 

return to above-normal conditions from 2007 to the present 

(2009). Mean annual precipitation for the period of record 

(1942–2008) at the Ruidoso climate station is 22.21 in/yr (fig. 

3A) with a range from 12.27 inches in 1970 to 34.81 inches in 

1965.

Mean monthly precipitation for the Ruidoso and Sierra 

Blanca climate stations indicates that about 65 and 58 percent, 

respectively, of annual precipitation falls during June through 
10 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009 Table 2. Annual and mean precipitation, in inches, and station elevation, in feet above the North American Vertical Datum of 1988 (NAVD 88), for climate stations in the Upper Rio Hondo Basin, south-central New Mexico. [--, no data; M, not used in calculation of mean because 6 or more days of data from 1 or more months during a year are missing; locations of climate stations shown in fig. 1] Year Fort Stanton 1910–30 data from Powell (1954); 1931–74 data from National Climatic Data Center (2009a) and Western Region Climate Center (2009) Capitan 1910–30 data from Powell (1954); 1931–2008 data from National Climatic Data Center (2009a) and Western Region Climate Center (2009) Mayhill Ranger Station data from National Climatic Data Center (2009a) and Western Region Climate Center (2009) Mountain Park data from Western Region Climate Center (2009) Ruidoso data from National Climatic Data Center (2009a) and Western Region Climate Center (2009) Whitetail 1915–30 data from Powell (1954); rest of data from Western Region Climate Center (2009) Cloudcroft data from National Climatic Data Center (2009a) and Western Region Climate Center (2009) Sierra Blanca data from Natural Resources Conservation Service (2009) 1910 12.89 12.43 -- -- -- -- 15.89 -- 1911 20.48 20.33 -- -- -- -- 16.42 M -- 1912 18.49 19.19 -- 18.62 M -- -- 22.88 -- 1913 16.20 14.87 -- 19.88 -- -- 14.71 M -- 1914 16.60 20.92 -- 22.09 M -- -- 21.75 -- 1915 20.04 17.89 -- 21.19 -- 24.45 25.58 -- 1916 14.90 19.70 -- 17.68 -- 24.57 27.42 -- 1917 9.79 9.72 17.06 M 16.47 -- 18.45 15.01 -- 1918 15.17 18.02 18.57 23.14 -- 21.54 28.52 -- 1919 23.11 22.24 21.76 23.84 -- -- 31.94 -- 1920 14.53 16.46 21.01 17.65 -- 19.71 23.67 M -- 1921 19.61 13.93 25.38 21.30 -- 23.89 18.76 -- 1922 8.78 8.40 14.69 14.24 -- -- 16.60 -- 1923 14.99 16.98 21.85 24.77 -- 24.59 29.07 -- 1924 9.76 11.77 11.07 4.9 M -- 16.70 16.98 -- 1925 16.88 15.62 20.22 2.97 M -- 21.57 24.29 -- 1926 20.87 M 25.44 27.65 0 M -- 28.36 31.80 --

1927 12.26 11.77 11.01 M 0 M -- 20.50 29.79 --1928 8.89 M 17.01 16.63 13.36 M -- 16.81 25.99 --1929 14.32 17.20 21.05 11.78 M -- 25.19 22.7 M --1930 13.26 14.52 14.91 M 0 M -- 19.37 25.81 --1931 20.51 24.47 29.25 20.16 -- 30.06 42.32 --1932 17.80 23.38 22.21 14.97 -- 20.44 35.54 --1933 9.14 13.76 16.35 19.09 -- 21.75 22.74 --
Hydrology of the Eagle Creek Basin Study Area 11

1934 8.68 10.17 10.24 3.82 M -- 13.02 17.15 --1935 13.74 17.77 20.23 16.20 -- 22.47 20.68 --1936 17.70 22.34 26.65 18.91 M -- 20.90 27.50 --1937 16.91 21.87 20.45 15.12 -- 43.22 27.16 --1938 15.47 21.11 24.60 22.14 -- 29.61 25.99 --1939 14.64 16.95 15.11 19.09 -- 24.03 24.56 --1940 13.18 15.10 19.89 14.11 -- 24.89 24.51 --1941 25.63 M 30.74 42.96 39.92 M .08 M 62.45 48.10 --1942 0 M 10.88 27.28 23.39 27.95 32.33 31.89 --1943 3.05 M -- 16.68 9.45 M 10.76 M 4.88 M 24.85 --1944 16.17 -- 17.79 11.26 M 20.68 20.49 25.54 --1945 6.06 .18 M 14.62 8.33 M 9.43 M 13.24 18.49 --1946 12.76 10.26 16.08 14.44 24.81 16.91 M 26.20 --1947 9.28 9.21 14.62 8.16 M 14.50 9.48 M 13.37 M --1948 15.35 13.81 15.88 18.57 22.69 9.97 M 16.72 M --1949 16.91 18.71 25.66 20.35 25.42 -- 31.87 --1950 13.91 14.12 20.98 12.99 21.85 -- 21.00 --1951 10.70 8.67 8.60 16.77 21.94 -- 23.31 --1952 12.60 12.45 15.38 9.89 21.55 -- 24.52 --1953 13.58 10.90 9.96 17.12 18.74 -- 16.4 M --1954 14.26 13.46 15.50 14.59 19.97 12.53 M 19.83 --1955 14.49 12.85 17.51 19.05 18.51 0.86 M 26.83 --1956 9.37 9.12 8.03 10.37 14.71 15.98 17.72 --1957 18.65 21.26 22.36 20.93 24.57 23.96 27.63 --1958 19.11 17.16 18.65 25.43 26.51 23.67 37.80 --1959 15.76 14.16 14.79 13.23 19.51 1.55 M 21.06 --1960 15.39 11.40 18.66 23.37 15.73 -- 23.05 --1961 12.13 15.99 16.85 26.05 25.14 -- 30.64 --1962 15.04 16.77 21.34 20.85 23.23 -- 28.47 --1963 8.87 8.00 14.89 17.28 19.97 -- 24.44 --1964 9.75 12.33 11.04 10.49 M 17.42 -- 21.33 --1965 15.37 16.24 21.53 21.74 M 34.81 -- 33.93 --1966 10.82 4.28 M 19.34 18.19 16.51 -- 24.53 --1967 11.28 -- 19.35 17.16 20.84 -- 26.03 --1968 12.54 -- 21.40 14.40 M 18.69 -- 27.09 --
12 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009 1969 14.09 -- 25.40 21.95 M 21.94 -- 27.47 -- 1970 8.32 -- 15.63 10.27 12.27 -- 15.33 -- 1971 13.31 -- 18.50 20.64 22.97 -- 23.90 -- 1972 20.81 -- 24.50 26.15 26.63 -- 32.65 -- 1973 2.44 M -- 13.38 14.56 20.49 -- 17.87 M -- 1974 12.52 -- 28.03 26.98 24.28 -- -- -- 1975 -- -- 14.33 16.3 M 20.10 -- -- -- 1976 -- 15.30 13.27 M 22.29 20.86 -- -- -- 1977 -- 15.50 -- 17.15 20.55 -- -- -- 1978 -- 18.06 -- 29.19 32.42 -- -- -- 1979 -- 17.21 -- 19.99 19.56 -- 1.82 M -- 1980 -- 18.12 -- 17.32 19.65 -- 24.49 -- 1981 -- 17.72 -- 19.88 19.37 M -- 29.17 -- 1982 -- 19.14 -- 21.52 23.54 -- 28.86 -- 1983 -- 18.59 -- 23.84 17.90 -- 29.23 -- 1984 -- 22.44 -- 29.10 30.05 -- 35.82 -- 1985 -- 17.95 -- 28.44 24.26 -- 35.96 --

1986 -- 25.49 -- 24.69 29.54 -- 40.13 --1987 -- 20.20 -- 19.01 18.5 M -- 16.41 --1988 -- 19.18 -- 21.16 28.74 -- 36.01 --1989 -- 12.40 -- 14.92 20.76 -- 26.71 --1990 -- 18.56 -- 23.88 27.53 -- 31.39 --1991 -- 20.41 -- 26.46 24.25 -- 39.24 --1992 -- 16.43 -- 19.67 23.20 -- 31.99 --

Year

Fort Stanton

1910–30 data from 

Powell (1954); 

1931–74 data from 

National Climatic 

Data Center (2009a) 

and Western Region 

Climate Center (2009) 

Capitan 1910–30 

data from Powell 

(1954); 1931–2008 

data from 

National Climatic 

Data Center (2009a) 

and Western Region 

Climate Center 

(2009) 

Mayhill Ranger 

Station data 

from National 

Climatic Data 

Center (2009a) 

and Western 

Region Climate 

Center (2009) 

Mountain Park 

data from 

Western Region 

Climate Center 

(2009) 

Ruidoso data 

from National 

Climatic Data 

Center (2009a) 

and Western 

Region Climate 

Center (2009) 

Whitetail 1915–30 

data from 

Powell (1954); 

rest of data from 

Western Region 

Climate Center 

(2009) 

Cloudcroft data 

from National 

Climatic Data 

Center (2009a) 

and Western 

Region Climate 

Center (2009) 

Sierra Blanca 

data from 

Natural Resources 

Conservation 

Service (2009)

Table 2. Annual and mean precipitation, in inches, and station elevation, in feet above the North American Vertical Datum of 1988 (NAVD 88), for climate stations in the Upper Rio Hondo Basin, south-central New Mexico.—Continued[--, no data; M, not used in calculation of mean because 6 or more days of data from 1 or more months during a year are missing; locations of climate stations shown in fig. 1] 
Hydrology of the Eagle Creek Basin Study Area 13

1993 -- 17.04 -- 21.25 11.37 M -- 33.91 --1994 -- 16.93 -- 19.56 22.10 -- 33.81 --1995 -- 12.32 -- 22.26 19.10 -- 25.17 --1996 -- 17.12 -- 16.90 23.55 -- 27.19 --1997 -- 21.88 -- 25.04 25.87 -- 31.46 --1998 -- 12.73 M -- 24.87 M 14.00 M -- 29.28 --1999 -- 13.95 -- 16.69 16.03 M -- 22.61 --2000 -- 15.90 -- 15.55 18.21 -- 26.49 --2001 -- 11.21 M -- 16.15 19.92 -- 28.24 --2002 -- 16.06 -- 20.64 17.90 -- 28.75 8.2 M2003 -- 3.59 M -- 11.92 13.53 -- 19.18 27.302004 -- 13.57 M -- 19.54 20.92 -- 27.51 41.402005 -- 16.83 -- 21.16 19.35 M -- 21.26 M 35.702006 -- 22.48 -- 26.26 32.41 -- 41.20 49.702007 -- 19.07 -- 22.35 24.15 -- 32.30 M 37.602008 -- 13.06 M -- 14.38 M 25.10 -- 27.09 M 35.80

Elevation 6,220 6,470 6,570 6,790 6,860 7,450 8,710 10,280

Mean 14.23 16.55 18.69 19.57 21.87 22.59 26.72 36.70
14 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

October, with about 39 and 35 percent, respectively, falling 

during July and August (fig. 3B). Seasonal trends generally are 

similar between the two stations. Mean monthly precipitation 

is lowest in March, April, May, and November.

Snow-water equivalent (SWE), or the water content of 

the snowpack, is the amount of water that would result from 

melting of the snowpack. At the Sierra Blanca station, SWE 

reaches its maximum in February through April, typically 

peaking in late February or early April (Natural Resources 

Conservation Service, 2009). The highest SWE recorded at the 

Sierra Blanca climate station was 20.2 inches on April 2–3, 

2005 (Natural Resources Conservation Service, 2009). SWE 

data indicate that snowpack melting generally begins in March 

or April and is typically complete by late April or early May.

Surface Water

The headwaters of the North Fork Basin lie at about 

10,500 ft elevation. Stream runoff occurs predominantly 

during two periods, the spring snowmelt and summer 

monsoon seasons. Because of steep slopes within the basin, 

high-magnitude runoff carries bedload deposits of up to 

boulder-size material. The stream channel in the vicinity of the 

North Fork well field was filled at or near bankfull level with 

bedload deposits during the period of this study. Streamflow 

may infiltrate below the channel surface in reaches with large 

quantities of bedload deposits, sometimes reemerging farther 

downstream where bedload deposits are thinner or where the 

channel bottom is bedrock. Within the study area, the North 

Fork typically is perennial in the upper reaches and, depending 

on streamflow, may be intermittent in about the lower 2 

mi, which is where the larger deposits of bedload occur. An 

observation from a long-time resident of the seasonal cabins 

suggests that flow is generally continuous to at least about 

500 ft below the North Fork gaging station (G. Sears, oral 

commun., 2008). Another resident recalled that, during the 

drought period of the 1950s, the stream was dry to a point 

above the upper cabins, although water was obtainable by 

digging into the streambed.

Numerous steep side drainages empty into the main 

canyon of the North Fork. Contributions from these drainages 

are episodic, coinciding with intense storms. In addition, 

persistent flows were observed during the spring of 2007 and 

2008 in Johnson and Carlton Canyons.

Groundwater

Precipitation in the Sacramento Mountains is the primary 

source of groundwater recharge. Recharge of precipitation to 

groundwater occurs in part as infiltration through the channel 

bottoms of major and minor drainages and to a lesser extent 

through fractures on rock outcrops (Newcomer and Shomaker, 

1991). During this study, discrete zones of channel infiltration 

and groundwater discharge were noted in Eagle Creek along 

local-scale faults and fractures. 

Groundwater recharge on the eastern flank of the 

Sacramento Mountains generally flows to the east along joints 

and bedding plane pathways in both the volcaniclastic and 

sedimentary rocks (Mourant, 1963). The primary porosity 

of the Sierra Blanca volcaniclastic rocks is low (Newcomer 

and Shomaker, 1991), but porosity has been enhanced by 

later fracturing and faulting. Many small springs discharge 

groundwater from the igneous rocks where the water table 

intersects land surface or along contacts between units of 

different hydrologic properties (Mourant, 1963).

Long-Term Water Balance

A long-term (1970–2008) water balance was constructed 

for the study area to provide estimates of the volume of 

surface water and groundwater discharging from the basin. 

Water-balance components include estimates of base flow and 

direct runoff, precipitation, evapotranspiration, basin yield, 

and groundwater recharge. Basin yield is partitioned into 

estimates of surface-water and groundwater volumes.

Base Flow and Direct Runoff

Base flow at the Eagle Creek gaging station was 

estimated by using a digital-filter method described by 

Lim and others (2005). The digital-filter method is based 

on the assumption that streamflow-runoff events can be 

represented by a high-frequency signal and that base flow can 

be represented by a low-frequency signal (Eckhardt, 2005). 

The Web-based hydrograph-separation tool, WHAT (Lim and 

Engel, 2004; Lim and others, 2005), was used to perform a 

base-flow analysis of streamflow data from the Eagle Creek 

gaging station. Streamflow data uploaded to WHAT were 

processed by using the recursive digital-filter option with a 

filter parameter of 0.98 and a base-flow index (BFI) of 0.40.

The resulting base-flow analysis (fig. 5 and table 3) 

indicates that the 1970–80 mean annual discharge, direct 

runoff, and base flow were 2,260, 1,440, and 819 acre-ft/yr, 

respectively (table 4). Mean annual discharge, direct runoff, 

and base flow for 1989–2008 were 1,290, 871, and 417 acre-ft/

yr, respectively (table 4). These results indicate that mean 

annual discharge, direct runoff, and base flow were less during 

the 1989–2008 period than during the 1970–80 period but 

that the amount of direct runoff and base flow as a percent of 

measured discharge was similar for the two periods (table 4).

Precipitation

The long-term annual precipitation over the study area 

was estimated by using mean annual precipitation values and 

climate-station elevations. Precipitation data compiled from 

the National Climatic Data Center (2009a), Western Region 

Climate Center (2009), Natural Resources Conservation 

Service (2009), and Powell (1954) (table 2) were used to 

estimate mean annual precipitation values for eight climate 
Hydrology of the Eagle Creek Basin Study Area 15

0

50

100

150

200

A

0

5

10

B 

DISCHARGE, IN CUBIC FEET PER SECOND

No data—gage

was not operated

during this period

No data—gage

was not operated

during this period

1968

1970

1975

1980

1985

19901995

2000

2005

2008

1968

1970

1975

1980

1985

19901995

2000

2005

2008

stations in the Upper Rio Hondo Basin (table 2 and fig. 1). 

The precipitation data range in time from 1910 to 2008. 

Precipitation records from the eight stations cover varying 

time periods and are sometimes discontinuous within a given 

station record. Data from the maximum available time period 

was used to estimate precipitation in order to compensate 

for data discontinuities and climatic variability (wet and 

dry periods) that would affect estimated precipitation over 

the study area. Mean annual precipitation for each climate 

station was estimated by using data between the 25th and 75th 

percentiles of the data distribution so that the estimate of the 

mean was less influenced by extreme values in the station 

record. Climate-station elevations (table 2) were obtained 

from Western Region Climate Center (2009). Mean annual 

precipitation values ranged from 14.23 inches at the Fort 

Stanton climate station at an elevation of 6,220 ft to 36.70 

inches at the Sierra Blanca climate station at an elevation of 

10,280 ft (table 2). Even though all of the climate stations do 

not have concurrent annual precipitation data, the mean annual 

precipitation clearly increases with increasing elevation (fig. 

6). A linear-regression estimate of the relation of climatestation elevation to mean annual precipitation is

, (1)

where

P = mean annual precipitation, in inches; and

E = climate-station elevation, in feet above 

 NAVD 88.

Figure 5. Base-flow analysis for the Eagle Creek gaging station (08387600) in south-central New Mexico, August 27, 1969, to December 

31, 2008. A, The average mean daily reported discharge. B, The average mean daily base flow from base-flow analysis.
16 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

Table 3. Results of base-flow analysis of discharge data from the Eagle Creek gaging station (08387600) in south-central New Mexico, 

August 27, 1969, to December 31, 2008.

[acre-ft/yr, acre-feet per year; –, no data]

Year

Mean annual discharge, in acre-ft/yr

Measured discharge Estimated direct runoff Estimated base flow Comment

1969 847 563 284 Streamflow record begins on August 27, 1969

1970 836 525 311

1971 527 346 181

1972 2,540 1,630 903

1973 3,350 2,080 1,260

1974 2,460 1,600 862

1975 2,850 1,780 1,070

1976 1,350 864 486

1977 1,500 984 516

1978 3,850 2,810 1,040

1979 4,000 2,220 1,780

1980 1,620 1,020 599 Streamflow record ends on December 31, 1980

1981 – – –

1982 – – –

1983 – – –

1984 – – –

1985 – – –

1986 – – –

1987 – – –

1988 2,220 1,510 712 Streamflow record resumes on April 27, 1988

1989 1,180 775 409

1990 1,880 1,320 556

1991 3,300 2,120 1,180

1992 2,830 1,830 994

1993 2,130 1,350 780

1994 943 707 236

1995 775 451 324

1996 458 328 131

1997 2,110 1,440 671

1998 2,360 1,650 708

1999 410 269 142

2000 411 300 111

2001 401 272 129

2002 113 95 18

2003 152 110 42

2004 396 306 90

2005 1,360 916 444

2006 1,970 1,400 566

2007 1,310 830 479

2008 1,290 954 333
Hydrology of the Eagle Creek Basin Study Area 17

F ort Stanton

C apitan

Ma y hil l

M ountain Park

Ruidoso Whitetail

Cloudcroft

Sierra Blanca

Regressio n li ne:

precipitatio n = 0 .0049 x elev atio n - 14.42

R 2 (coefficient of determination) = 0.96

10

15

20

25

30

35

40

5,000 6,000 7,000 8,000 9,000 10,000 11,000

ELEVATION, IN FEET REFERENCED TO NAVD 88

PRECIPITATION, IN INCHES

Table 4. Mean annual measured discharge, direct runoff, and base flow for the Eagle Creek gaging station (08387600) in south-central 

New Mexico, 1970–80 and 1989–2008.

[acre-ft/yr, acre-feet per year]

Years

Mean 

annual 

measured 

discharge, 

in acre-ft/yr

Mean 

annual 

direct 

runoff, in 

acre-ft/yr

Direct runoff as 

a percentage 

of mean annual 

measured 

discharge

Mean 

annual base 

flow, in 

acre-ft/yr

Base flow as a 

percentage of 

mean annual 

measured 

discharge Comment

1970–80 2,260 1,440 64 819 36 Means do not include incomplete years (1969 

and 1988)

1989–2008 1,290 871 68 417 32

Figure 6. Relation of mean annual precipitation and elevation for climate stations in the Sacramento, Sierra Blanca, and Capitan 

Mountain areas, New Mexico (NAVD 88, North American Vertical Datum of 1988).
18 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

The coefficient of determination (R2) for the linear 

regression is 0.96, and the standard error of the precipitation 

estimate is ±1.60 inches (Helsel and Hirsch, 2002).

The study area was subdivided into the North Fork Eagle 

Creek Basin and the South Fork Eagle Creek Basin, plus a 

small area contributing to Eagle Creek between the confluence 

of the North and South Forks and the Eagle Creek below 

South Fork gaging station (Eagle Creek below confluence 

contributing area). The North Fork Eagle Creek Basin, the 

South Fork Eagle Creek Basin, and the Eagle Creek below 

confluence contributing area were further divided into 500-

ft elevation bands (fig. 7) by using land-surface elevation 

contours from the USGS 1:24,000-scale Nogal quadrangle 

topographic map.

Equation 1 was used to estimate the amount of mean 

annual precipitation for each of the elevation bands defined for 

the study area (table 5). Mean annual precipitation volumes for 

the North Fork Eagle Creek Basin, the South Fork Eagle Creek 

Basin, and the Eagle Creek below confluence contributing area 

are estimated to be 8,160, 4,030, and 17.0 acre-ft, respectively 

(table 5). The mean annual precipitation volume for the study 

area is estimated to be 12,200 acre-ft (table 5). The standard 

error of the precipitation estimate (±1.60 inches) indicates 

that the actual estimate of precipitation volume could vary 

from the calculated amount by about ±610 acre-ft or about 5 

percent.

Evapotranspiration

Evapotranspiration was estimated by using two 

methods: (1) a relation between annual precipitation and 

evapotranspiration based on paired basin studies conducted in 

Colorado (MacDonald and Stednick, 2003) and (2) a reference 

evapotranspiration calculated by using the Blaney and Criddle 

(1962) method and a Douglas fir (Pseudotsuga menziesii) crop 

coefficient curve (New Mexico Climate Center, 2009a).

The first method of estimating actual evapotranspiration 

used the MacDonald and Stednick (2003, p. 7) relation 

between annual precipitation and evapotranspiration in the 

Fraser Experimental Forest of Colorado (modified from units 

of millimeters to inches):

, (2)

where 

ET = actual evapotranspiration, in inches; and 

P = annual precipitation, in inches.

In this method, MacDonald and Stednick (2003) 

indicated that until annual precipitation in mountain basins 

exceeded 18.11 inches, all of the precipitation was either 

transpired by vegetation or evaporated from soil. Annual 

precipitation at all locations over the study area was estimated 

to be greater than 18.11 inches (table 5). In addition, about 28 

percent of annual precipitation in excess of 18.11 inches was 

assumed to be intercepted by and evaporated from vegetation 

(represented by the expression 0.28(P – 18.11) in equation 

2). The remaining 72 percent of annual precipitation in 

excess of 18.11 inches becomes water yield from the basin 

(MacDonald and Stednick, 2003). An assumption of this 

method is that in nonforested areas (where vegetation does 

not intercept precipitation) evapotranspiration is less than in 

forested areas.

The percent of forested area for each elevation band was 

estimated by using percent tree-canopy data obtained from the 

Multi-Resolution Land Characteristics Consortium (2001). 

The tree-canopy data indicate the percent of land surface that 

is covered by trees at a 30- × 30-m resolution. Tree-canopy 

cover ranged from 0 to 100 percent in all of the elevation 

bands; the average canopy cover in the North Fork Eagle 

Creek Basin was about 69 percent, in the South Fork Eagle 

Creek Basin was about 65 percent, and in the Eagle Creek 

below confluence contributing area was about 83 percent.

The average percent canopy cover for each elevation 

band was used to reduce the amount of precipitation 

intercepted and evaporated by vegetation in equation 2. Thus, 

equation 2 was modified as follows:

, (3)

where

ET and P are as defined in equation 2; and

C = fraction of land surface covered by tree 

canopy, dimensionless, ranging from 0 to 

1.

If equation 3 is used, then areas with 0 percent canopy 

cover would have evapotranspiration of 18.11 inches, 

and areas with 100 percent canopy cover would have 

evapotranspiration of 18.11+0.28(P – 18.11) inches. 

Estimated annual evapotranspiration for the North Fork Eagle 

Creek Basin, the South Fork Eagle Creek Basin, and the Eagle 

Creek below confluence contributing area calculated by using 

equation 3 is 5,780, 2,940, and 13.6 acre-ft, respectively, and 

for the study area is 8,730 acre-ft (table 6).

The second method of estimating evapotranspiration 

was the Blaney and Criddle (1962) method that relates mean 

daily temperature and number of daylight hours to the daily 

potential evapotranspiration of a grass reference crop. The 

Blaney and Criddle (1962) equation is

,

(4)

where

ET0 = grass reference crop evapotranspiration, in 

millimeters per day;

 = mean daily percent of annual daytime 

hours; Tmax = mean daily maximum temperature, in 

degrees Celsius; and Tmin = mean daily minimum temperature, in 

degrees Celsius.

P
Hydrology of the Eagle Creek Basin Study Area 19

105°47' 105°46' 105°45' 105°44'

33°25'

33°24'

33°23'

0 2,000 6,000 FEET

0 1,000 2,000 METERS

3,000

9,250 Elevation band and mid-elevation of band

EXPLANATION

Streamflow-gaging station and number

Eagle Creek below

South Fork near

Alto, N. Mex.

(08387600)

8,250

8,750

8,250

9,250

8,750

9,750

7,750

7,750

10,250

9,250

9,750

10,250

10,750

9,250

7,750

9,250

8,250

9,250

8,250

9,250

8,750

9,250

South Fork Eagle Creek Basin

North Fork Eagle Creek Basin

Eagle Creek 

contributing area

below confluence of 

North Fork and South 

Fork Eagle Creek

South Fork Eagle Creek

North Fork Eagle Creek

Eagle

Creek

Base from New Mexico Geospatial Data Acquisition Coordination Committee, 2006, 1:12,000

Universal Transverse Mercator projection 

Zone 13

Eagle Creek

below South

Fork near

Alto, N. Mex.

(08387600)

Figure 7. Elevation bands used in water-balance calculations for the Eagle Creek Basin above the Eagle Creek gaging station 

(08387600) in south-central New Mexico.
20 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009 Table 5. Estimated mean annual precipitation for the elevation bands in the Eagle Creek Basin, New Mexico. [The values and sums for area and the precipitation volume are rounded to three significant figures] Basin or contributing area Elevation band, in feet Mid-elevation of band, in feet Area of elevation band, in acres Mean annual precipitation from equation 1, in inches1 Mean annual precipitation volume, in acre-feet Range of error in mean annual precipitation volume based on a ±5 percent error, in acre-feet North Fork Eagle Creek 10,500–11,000 10,750 28.5 38.3 91.0 ±4.55 North Fork Eagle Creek 10,000–10,500 10,250 192 35.8 573 ±28.6 North Fork Eagle Creek 9,500–10,000 9,750 358 33.4 996 ±49.8 North Fork Eagle Creek 9,000–9,500 9,250 593 30.9 1,530 ±76.3 North Fork Eagle Creek 8,500–9,000 8,750 953 28.5 2,260 ±113 North Fork Eagle Creek 8,000–8,500 8,250 978 26.0 2,120 ±106 North Fork Eagle Creek 7,500–8,000 7,750 301 23.6 592 ±29.6 North Fork Eagle Creek totals 3,400 8,160 ±408 South Fork Eagle Creek 10,000–10,500 10,250 38.5 35.8 115 ±5.75 South Fork Eagle Creek 9,500–10,000 9,750 82.6 33.4 230 ±11.5 South Fork Eagle Creek 9,000–9,500 9,250 167 30.9 430 ±21.5 South Fork Eagle Creek 8,500–9,000 8,750 421 28.5 1,000 ±50.0 South Fork Eagle Creek 8,000–8,500 8,250 820 26.0 1,780 ±88.8 South Fork Eagle Creek 7,500–8,000 7,750 241 23.6 474 ±23.7 South Fork Eagle Creek totals 1,770 4,030 ±202 Eagle Creek below South Fork 8,000–8,500 8,250 0.760 26.0 1.6 ±0.080 Eagle Creek below South Fork 7,500–8,000 7,750 7.66 23.6 15.1 ±0.755 Eagle Creek below South Fork totals 8.42 17.0 ±0.835 Eagle Creek Basin totals 5,180 12,200 ±610

1Equation 1: 

P = 0.0049 x 

E - 14.42, where 

P = mean annual precipitation, in inches; and 

E = mid-elevation of the elevation band, in feet.
Hydrology of the Eagle Creek Basin Study Area 21

Table 6. Estimated mean annual evapotranspiration for elevation bands in the Eagle Creek Basin, New Mexico.[Standard error of MacDondald and Stednick (2003) estimate is 7.5 percent (Troendle and Reuss, 1997); all evapotranspiraton values rounded to three significant figures]

Basin or contributing area

Elevation band, 

in feet

Area of 

elevation 

band, in 

acres

Fraction 

of land 

surface 

covered 

by tree 

canopy

Mean annual estimated evapotranspiration

Average of 

evapotranspiration 

from MacDonald and 

Stednick (2003) and 

Blaney and Criddle 

(1962) methods, in 

acre-feet

Range of error in average 

evapotranspiration based 

on a ± 7.5 percent error in 

the estimate of MacDonald 

and Stednick (2003) 

evapotranspiration, in 

acre-feet

1MacDonald and 

Stednick (2003) 

evapotranspiration 

based on equation 3 

and area of elevation 

band, in acre-feet

2Blaney and 

Criddle (1962) 

evapotranspiration 

based on equation 4 and area of 

elevation band, in 

acre-feet

North Fork Eagle Creek 10,500-11,000 28.5 0.35 47.7 42.1 44.9 ±3.37North Fork Eagle Creek 10,000-10,500 192 0.55 333 295 314 ±23.6North Fork Eagle Creek 9,500-10,000 358 0.61 618 571 595 ±44.6North Fork Eagle Creek 9,000-9,500 593 0.72 1,020 979 1,000 ±75.0North Fork Eagle Creek 8,500-9,000 953 0.86 1,640 1,630 1,640 ±123North Fork Eagle Creek 8,000-8,500 978 0.87 1,630 1,730 1,680 ±126North Fork Eagle Creek 7,500-8,000 301 0.84 487 548 518 ±38.9North Fork Eagle Creek 

totals 3,400 5,780 5,800 5,790 ±434

South Fork Eagle Creek 10,000-10,500 38.5 0.31 63.0 59.2 61.1 ±4.58South Fork Eagle Creek 9,500-10,000 82.6 0.76 147 132 139 ±10.4South Fork Eagle Creek 9,000-9,500 167 0.74 290 275 282 ±21.2South Fork Eagle Creek 8,500-9,000 421 0.71 710 718 714 ±53.6South Fork Eagle Creek 8,000-8,500 820 0.68 1,340 1,446 1,390 ±104South Fork Eagle Creek 7,500-8,000 241 0.70 385 439 412 ±30.9South Fork Eagle Creek 

totals 1,770 2,940 3,070 3,010 ±226

Eagle Creek below South Fork 8,000-8,500 0.760 0.86 1.27 1.34 1.31 ±0.098Eagle Creek below South Fork 7,500-8,000 7.66 0.80 12.3 14.0 13.2 ±0.990Eagle Creek below South 

Fork totals 8.42 13.6 15.3 14.5 ±1.09

Eagle Creek Basin totals 5,180 8,730 8,890 8,810 ±661

1Equation 3: ET=18.11+C[0.28(P-18.11)], where ET = evapotranspiration, in inches; C = fraction of land surface covered by tree canopy, dimensionless, ranging from 0 to 1; and P = annual precipitation, in 

inches.

2Equation 4: ET0=p[0.46(Tmax-Tmin)/2)+8], where ET0 = grass reference crop evapotranspiration, in millimeters per day; p = mean daily percent of daytime hours; Tmax = mean daily maximum temperatue, in 

degrees Celsius; and Tmin = mean daily minimum temperature, in degrees Celsius.
22 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

A climatic normal is the average of a climatic dataset 

based on a standard 30-year time period, calculated by the 

National Oceanic and Atmospheric Administration’s (NOAA) 

National Weather Service (NOAA, 2010). The time period 

1971–2000 defines the current 30-year normal period (NOAA, 

2010), and normal temperature data from this time period 

were used in the evapotranspiration analysis. To simplify 

the analysis, the 1971–2000 mean monthly maximum 

and minimum temperatures at the Ruidoso climate station 

were used instead of mean daily maximum and minimum 

temperatures. Values of p were derived from standard tables of 

mean daily percentage of annual daytime hours, tabulated by 

day of the year and latitude (Jensen and others, 1990). Values 

of P for the Blaney-Criddle equation were computed by using 

the mean latitude of the study area and the day of the year, and 

were decreased by 25 percent of the initial values based on the 

percent of possible sunshine for Albuquerque and Roswell, 

New Mexico (76 and 74 percent, respectively, National 

Climatic Data Center, 2009b). Albuquerque and Roswell are 

the nearest climate stations to the study area for which data are 

available.

The potential evapotranspiration calculated in equation 4 

was then adjusted by applying a crop coefficient to obtain the 

final estimated evapotranspiration:

, (5)

where 

ETc = crop evapotranspiration, in millimeters per 

day; kc crop coefficient, dimensionless; and

ET0 = is as defined in equation 4.

The crop coefficient c k was computed for each month 

on the basis of a crop-coefficient equation for Douglas fir 

obtained from the New Mexico Climate Center (2009a):

, (6)

where 

c k is as defined in equation 5; and

 = mean monthly cumulative growing-degree 

days, in days.

Calculated crop-coefficient values, ranging from 0.50 to 

0.70, were lowest in October–December and were highest in 

May.

Monthly cumulative growing-degree days were 

calculated as 

,

(7)

where

G = mean monthly cumulative growing-degree 

days, in days;

Tmax = mean monthly maximum temperature, in 

degrees Celsius;

Tmin = mean monthly minimum temperature, in 

degrees Celsius;

Tbase = base temperature below which no plant 

growth occurs, in degrees Celsius; and D = number of days in the month for which G

is being calculated, in days.

Mean monthly cumulative growing-degree days were 

computed by using 1971–2000 mean monthly temperatures for 

the Ruidoso climate station (Western Region Climate Center, 

2009), a base temperature of 5 degrees Celsius (oC; 41 degrees 

Fahrenheit [oF]), and an upper cutoff temperature of 30oC 

(86oF). Months where the mean monthly temperature was less 

than 5oC were assigned zero growing-degree days; no months 

exceeded the upper cutoff mean monthly temperature of 30oC. 

Total growing-degree days for the year (sum of the January 

through December mean monthly growing-degree days) was 

about 3,410 days.

Estimated annual evapotranspiration values were 

computed as follows. Mean monthly 1971–2000 minimum 

and maximum temperature data were obtained for the Capitan 

and Ruidoso climate stations from the National Climatic Data 

Center (2009a). Mean monthly 1971–2000 minimum and 

maximum temperature data for the Cloudcroft and Picacho 

climate stations were obtained from the Western Region 

Climate Center (2009). Mean monthly 2000–2008 minimum 

and maximum temperature data for the Mescal climate station 

were obtained from New Mexico Climate Center (2009b). 

These five temperature stations were chosen because they 

have temperature records that include the time period 1971–

2000 and are located at distances and elevations reasonably 

close to Eagle Creek Basin (within about 35 mi distance and 

between about 5,000 ft and 8,700 ft elevation). The mean 

monthly temperature data were used to develop regression 

relations between minimum and maximum temperature and 

elevation for each month of the year (table 7). The regression 

relations were used to compute the mean monthly minimum 

and maximum temperatures for each elevation band (fig. 7). 

Equation 4 was then used to determine the mean monthly 

reference evapotranspiration. The mean monthly crop 

evapotranspiration values were calculated (equation 5) by 

using the crop coefficient for Douglas fir (determined from 

equation 6), and the resulting values were summed to compute 

the mean annual estimated evapotranspiration for each 

elevation band (table 6).

Estimated annual evapotranspiration for the North Fork 

Eagle Creek Basin, the South Fork Eagle Creek Basin, and the 

Eagle Creek below confluence contributing area calculated 

by using equations 4 and 5 are 5,800, 3,070, and 15.3 acre-ft, 

respectively, and for the study area is 8,890 acre-ft (table 6).

G

=
Hydrology of the Eagle Creek Basin Study Area 23

Table 7. Mean monthly minimum and maximum temperatures and elevations for selected climate stations in south-central New Mexico and regression equations relating temperature to elevation.[Period of record in parentheses beneath climate station name; R2, coefficient of determination from linear regression; Temp, temperature in degrees Celsius; Elev, elevation in feet above the North American Vertical Datum of 1988 (NAVD 88)]

Month

Mean monthly minimum temperatures, in degrees Celsius Regressions for minimum temperatures

Capitan

(1971–2000)

(Elev = 6,470)

Cloudcroft 

(1971–2000)

(Elev = 8,710)

Mescal

(2000–2008)

(Elev = 6,227)

Picacho

(1971–2000)

(Elev = 5,005)

Ruidoso

(1971–2000)

(Elev = 6,860) Equation R2

January -5.72 -6.64 -5.44 -3.87 -6.78 Temp = -0.0007108 x Elev - 0.934 0.71February -4.39 -5.45 -3.31 -2.43 -5.67 Temp = -0.0008279 x Elev + 1.291 0.69March -2.50 -3.74 -1.78 -0.05 -3.67 Temp = -0.0009611 x Elev + 4.085 0.76April 0.61 -0.54 2.07 3.84 -1.11 Temp = -0.0011668 x Elev + 8.783 0.65May 5.28 3.65 5.30 8.85 2.50 Temp = -0.0013218 x Elev + 13.961 0.59June 9.61 7.50 9.05 12.94 6.50 Temp = -0.0013778 x Elev + 18.342 0.60July 11.56 9.10 10.37 15.28 9.22 Temp = -0.0014959 x Elev + 21.117 0.67August 11.06 8.48 9.09 14.86 9.17 Temp = -0.0014875 x Elev + 20.486 0.63September 7.67 5.99 6.96 10.89 6.11 Temp = -0.0011779 x Elev + 15.408 0.67October 2.11 1.10 2.86 5.10 0.78 Temp = -0.0010232 x Elev + 9.239 0.68November -2.83 -3.57 -2.32 -0.45 -4.17 Temp = -0.000799 x Elev + 2.679 0.61December -5.56 -6.17 -5.39 -4.31 -6.89 Temp = -0.0004968 x Elev - 2.337 0.52

Mean monthly maximum temperatures, in degrees Celsius Regressions for maximum temperatures

Month

Capitan

(1971–2000)

(Elev = 6,470)

Cloudcroft 

(1971–2000)

(Elev = 8,710)

Mescal

(2000–2008)

(Elev = 6,227)

Picacho

(1971–2000)

(Elev = 5,005)

Ruidoso

(1971–2000)

(Elev = 6,860) Equation R2

January 9.28 5.16 7.95 13.68 9.72 Temp = -0.0020093 x Elev + 22.607 0.81February 11.67 6.51 9.81 15.64 11.33 Temp = -0.0021909 x Elev + 25.654 0.85March 15.28 9.49 13.09 18.74 14.44 Temp = -0.0022504 x Elev + 29.268 0.86April 19.44 13.80 19.15 23.27 18.39 Temp = -0.0024135 x Elev + 34.963 0.98May 24.00 18.23 22.20 27.34 22.83 Temp = -0.0022528 x Elev + 37.996 0.91June 28.67 22.53 27.88 31.66 27.50 Temp = -0.0023384 x Elev + 43.3 0.97July 28.28 22.04 26.50 31.85 26.89 Temp = -0.0024413 x Elev + 43.45 0.92August 26.56 20.70 25.94 29.97 25.89 Temp = -0.002348 x Elev + 41.525 0.97September 24.22 19.08 23.89 27.91 23.67 Temp = -0.0022267 x Elev + 38.657 0.97October 19.83 14.70 18.27 23.36 19.17 Temp = -0.0021165 x Elev + 33.229 0.89November 13.61 8.88 12.66 17.51 13.67 Temp = -0.0021009 x Elev + 27.325 0.90December 9.78 5.78 8.43 13.34 10.11 Temp = -0.0017916 x Elev + 21.479 0.82
24 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

Basin Yield

Basin yield includes both surface-water and groundwater 

outflow from a basin and is equivalent to precipitation minus 

evapotranspiration and storage. For a long-term water balance, 

steady-state conditions are assumed to apply. Inputs to the 

basin are equal to outputs from the basin and the storage term 

becomes zero. For a long-term water balance, basin yield is 

equivalent to precipitation minus evapotranspiration. Annual 

basin yield (table 8) for the North Fork Eagle Creek Basin, 

the South Fork Eagle Creek Basin, and the Eagle Creek below 

confluence contributing area was estimated as the residual 

of mean annual precipitation (table 5) minus the average 

of the annual evapotranspiration determined by using the 

MacDonald and Stednick (2003) and the Blaney and Criddle 

(1962) methods (table 6). The average of the two values was 

used in order to compensate for differences in the two methods 

of estimation. Estimated annual basin yield for the North Fork 

Eagle Creek Basin, the South Fork Eagle Creek Basin, and the 

Eagle Creek below confluence contributing area was 2,370, 

1,020, and 2.5 acre-ft, respectively, and for the study area was 

3,390 acre-ft or about 28 percent of precipitation (table 8).

Groundwater Recharge

Groundwater recharge is that portion of precipitation 

input to the basin that infiltrates to the groundwater system 

and may exit the basin as subusurface flow or as base flow to 

the stream. Groundwater recharge was estimated by using two 

methods, a basin yield and a chloride mass-balance method.

Basin Yield Method

Groundwater recharge can be estimated as that portion 

of basin yield (precipitation minus evapotranspiration) 

not attributable to surface water runoff. By subtracting the 

mean annual direct surface-water runoff (from the base-flow 

analysis) from the annual basin yield, annual groundwater 

recharge for Eagle Creek Basin was estimated to be 1,950 

acre-ft, or about 16 percent of precipitation (table 9). The 

accuracy of this recharge estimate is affected by uncertainty in 

the mean annual precipitation and annual evapotranspiration 

estimates (tables 5 and 6) and uncertainty in discharge 

measurements at the Eagle Creek gaging station. The 

combined estimated error for the precipitation (±610 acre-ft 

in table 5) and evapotranspiration (±661 acre-ft in table 

6) estimates is about ±1,270 acre-ft or about 37 percent of 

the estimated annual basin yield (table 8). The accuracy of 

discharge measurements at the Eagle Creek gaging station, 

based on USGS hydrographers’ assessments of stream 

conditions and measurement procedural limitations imposed 

by the gaging site from April 1988 to August 2008, was 

estimated to be ±165 acre-ft/yr (about 7.3 percent of the 1970–

80 mean annual discharge of 2,260 acre-ft), and the error in 

mean annual direct runoff was estimated to be ±105 acre-ft/

yr (about 7.3 percent of 1.440 acre-ft, table 9). Because annual 

recharge is estimated by subtracting mean annual direct runoff 

from annual basin yield, the cumulative error for the estimate 

of recharge was estimated to be ±1,380 acre-ft/yr (table 9). 

Thus, by this method of calculation, recharge falls within the 

range of 570 to 3,330 acre-ft/yr or about 5 to 27 percent of 

precipitation.

Chloride Mass-Balance Method

Groundwater recharge also was estimated by using a 

chloride mass-balance method (Anderholm, 1994, 2000). 

This method is based on the principle that chloride in bulk 

precipitation (wet and dry deposition and precipitation) 

is concentrated in recently precipitated water or shallow 

groundwater by evapotranspiration and is a conservative 

element in water (once in solution chloride tends to stay in 

solution). The method is applicable to areas where there is 

no appreciable source of chloride other than in precipitation. 

Direct surface-water runoff transports some of the chloride 

from precipitation out of the basin, the loss of which must 

be accounted for in the mass-balance equation. The addition 

of chloride from nonprecipitation sources, such as chloride 

from dissolution of rocks or discharges from domestic water 

softeners, will decrease the estimated recharge, resulting in 

recharge values that represent a minimum amount of recharge. 

The chloride mass-balance equation used to estimate recharge 

(Russell and Minor, 2002) is

,

(8)

where

R = recharge, in acre-ft; 

P = precipitation over the basin, in acre-ft; 

Cp = chloride concentration in bulk 

precipitation, in milligrams per liter; 

Cr = chloride concentration in recharge, in 

milligrams per liter;

 = chloride concentration in surface-water 

runoff, in milligrams per liter; and 

S = volume of direct surface-water runoff, in 

acre-ft.

The volume of recharge was estimated on the basis of 

chloride concentrations in surface-water samples collected 

from the North Fork gaging station location and chloride 

concentrations in bulk precipitation reported by Anderholm 

(1994, 2000), Phillips and others (1984), and Mattick and 

others (1987). Because chloride concentrations in water from 

the monitoring wells and North Fork wells NF-1 and NF-4 

were about twice as high as chloride concentrations in the 

North Fork, the North Fork chloride concentrations were used 

to represent Cr, the chloride concentration in recharge. The 

North Fork samples were collected at times of base flow when 

the flow in the North Fork was being maintained by discharge 

Csw
Hydrology of the Eagle Creek Basin Study Area 25

Table 8. Estimated annual Eagle Creek Basin yield and basin-yield error.[acre-ft, acre-feet; basin yield values rounded to three significant figures]

Basin and water-balance components

Basin yield, mean annual precipitation (table 5) minus 

average of annual evapotranspiration from 

Mac Donald and Stednick (2003) and Blaney and 

Criddle (1962) methods (table 6), in acre-ft

Estimate of error

Volume, in acre-ft Percent of precipitation

Minimum basin yield 

(minimum precipitation

[table 5] and maximum 

evapotranspiration [table 6]), 

in acre-ft

Maximum basin yield 

(maximum precipitation 

[table 5] and minimum 

evapotranspiration [table 

6]), in acre-ft

Range of basin 

yield error, in 

acre-ft

North Fork Eagle Creek Basin

Precipitation 8,160 100 7,750 8,570Evapotranspiration 5,790 71.0 6,220 5,360Basin yield 2,370 29.0 1,530 3,210 ±840

South Fork Eagle Creek Basin

Precipitation 4,030 100 3,830 4,230Evapotranspiration 3,010 74.7 3,240 2,780Basin yield 1,020 25.3 590 1,450 ±430

Eagle Creek below confluence contributing area

Precipitation 17.0 100 16.2 17.8Evapotranspiration 14.5 85.3 15.6 13.4Basin yield 2.5 14.7 0.60 4.40 ±1.90

Eagle Creek Basin

Precipitation 12,200 100 11,600 12,800Evapotranspiration 8,810 72.2 9,470 8,150Basin yield 3,390 27.8 2,130 4,650 ±1,270
26 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009 Table 9. Basin-yield water-balance components using 1910–2008 mean annual precipitation; 1970–80 mean annual discharge, direct runoff, and base flow; and 1970–80 and 1988–2008 North Fork well pumpage. [acre-ft, acre-feet] Water-balance component Volume, in acre-ft Percent of basin yield Percent of precipitation Range of water-balance component, in acre-ft Comment Mean annual basin yield (based on 1910–2008 precipitation record) 3,390 100 27.8 ±1,270 Range from table 8 Mean annual discharge (1970–80) 2,260 66.7 18.5 ±165 Ranges calculated assuming a discharge-measurement error of 7.3 percent Mean annual direct runoff from WHAT analysis (1970–80) 1,440 42.5 11.8 ±105 Mean annual base flow from WHAT analysis (1970–80) 819 24.2 6.7 ±60 Mean annual recharge (basin yield minus direct runoff) 1,950 57.5 16.0 ±1,380 Range calculated as the sum of ranges for mean annual basin yield and mean annual direct runoff 1970–80 Mean annual groundwater pumpage from North Fork wells 0.00 0.00 0.00 Mean annual groundwater outflow (basin yield minus mean annual discharge and pumping) 1,130 33.3 9.26 1988–2008 Mean annual groundwater pumpage from North Fork wells 578 17.1 4.74 Mean annual groundwater outflow (basin yield minus mean annual discharge and pumping) 552 16.3 4.52
Hydrology of North Fork Eagle Creek 27

of groundwater to the stream. Chloride concentrations in 

water from monitoring and North Fork wells may have been 

affected by the contribution of chloride from contact with 

chloride-bearing volcanic or sedimentary rocks. The chloride 

concentrations in water from the North Fork (table 10) ranged 

from 7.07 to 7.39 milligrams per liter (mg/L). 

Chloride concentrations in bulk precipitation averaged 

0.29 mg/L in a study of recharge in the Santa Fe, New 

Mexico, area (Anderholm, 1994) and averaged 0.3 in a study 

of mountain-front recharge in the Middle Rio Grande Basin, 

New Mexico (Anderholm, 2000). Phillips and others (1984) 

reported a chloride concentration in bulk precipitation near 

Socorro, New Mexico, of 0.375 mg/L, and Mattick and others 

(1987) estimated chloride concentration in bulk precipitation 

to be 0.35 mg/L at a site near Las Cruces, New Mexico. 

The average of these reported values (about 0.33 mg/L) was 

used in this study to calculate the amount of recharge over 

the study area. By using equation 8, and assuming that the 

concentration of chloride in direct surface-water runoff was 

equal to the chloride concentration in bulk precipitation, and 

by using the average 1970–80 annual direct runoff (1,440 

acre-ft) as computed in the base-flow analysis, the average 

annual recharge over the study area was estimated to range 

from about 485 to 502 acre-ft, or about 3.9 to 4.1 percent of 

precipitation (table 10), with an average of 490 acre-ft (4.0 

percent of precipitation). The average annual direct runoff 

for the 1970–80 time period was used in equation 8 because 

this time period is more representative of long-term natural 

conditions unaffected by pumping. It is important to note that 

the estimate of average annual recharge probably represents 

a long-term minimum value of recharge for the study area 

because the chloride concentration in the North Fork water 

could have been increased by contribution of chloride from 

nonprecipitation sources. An increase in chloride concentration 

in the North Fork water would result in a decrease in estimated 

recharge. The amount of recharge probably varies from year to 

year, depending on climate conditions, and may well be larger 

than the value calculated by using the chloride mass-balance 

approach.

Groundwater Discharge Out of the Basin

Mean annual basin yield, based on the 1910–2008 

precipitation record, was estimated to be 3,390 acre-ft. 

During 1970–80, mean annual discharge was 2,260 acre-ft. 

Groundwater flow out of the basin, estimated as the residual of 

mean annual basin yield minus mean annual discharge during 

1970–80, was 1,130 acre-ft (table 9) and represented about 33 

percent of basin yield. Mean annual discharge during 1970–80 

was also used to estimate groundwater flow out of the basin 

for the 1988–2000 time period because the 1970–80 time 

period is more representative of long-term natural conditions 

unaffected by pumping. Groundwater flow out of the basin 

for the period 1988–2000 was estimated as the residual of 

mean annual basin yield minus mean annual discharge during 

1970–80 and minus mean annual groundwater pumping 

during 1988–2000. Groundwater flow out of the basin (552 

acre-ft) was estimated to represent about 16 percent of basin 

yield, and mean annual groundwater pumping (578 acre-ft 

for 1988–2000) was estimated to be about 17 percent of basin 

yield (table 9).

Hydrology of North Fork Eagle Creek

The hydrology of the North Fork is discussed by using 

groundwater, water-chemistry, and surface-water data. These 

data are summarized in a conceptual model of North Fork 

Eagle Creek hydrology.

Groundwater

The groundwater hydrology of the North Fork is 

described by using borehole-log and groundwater data. Water 

levels in alluvial and bedrock wells are discussed.

Borehole Logs

In bedrock terranes in the study area, aquifer complexities 

are the result of hydraulic interaction between individual 

fractures and fracture networks. Fractures that are open, water 

saturated, and hydraulically connected serve to store and 

transmit water in the subsurface. A general understanding of 

subsurface fracturing in the upper Rio Hondo Basin can be 

gained by studying the topographic relief of the area (Lattman 

and Parizek, 1964; Walsh, 2008). Additional information 

on the distribution, orientation, and flow properties of rocks 

at depth requires the use of advanced borehole geophysical 

techniques. Geophysical analyses in the boreholes, prior to 

installation of the monitoring wells MW-1 and MW-4, were 

conducted by using caliper, natural gamma, single-point 

resistance, neutron, fluid temperature, and acoustic televiewer 

(ATV) logs (Zemanek and others, 1969; Keys, 1990; figs. 8 

and 9).

Borehole caliper and neutron logs from borehole MW-1 

on May 22, 2007, show fracture zones from 40 to 90 ft 

and from 230 to 310 ft (fig. 8). The negative shifts in the 

neutron log in those intervals indicate zones of heightened 

fracture porosity. Mineral oxidation was evident in drill 

cuttings in similar intervals from 20 to 30 ft and 240 to 

405 ft. The two distinct zones of oxidation corroborate 

evidence from continuous water-level measurements that 

indicates that fracture zones at various depths in the borehole 

are hydraulically separated by zones of lower fracture 

permeability. Below the lowermost oxidized zone, the MW-1 

gamma log exhibits a positive shift between 425 and 470 ft. A 

distinct change in andesite composition was noted at the top of 

this interval as a color change in cuttings from greenish gray 

to light gray. Drilling logs indicate that the light gray andesite 

was more competent and less fractured than the overlying 

greenish gray andesite. Similar results were obtained from 
28 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009 Table 10. Estimates of groundwater recharge using the chloride mass-balance approach for Eagle Creek Basin upstream from the Eagle Creek below South Fork near Alto, New Mexico, gaging station (08387600). [mg/L, milligram per liter; acre-ft, acre-feet] Date sample collected Chloride concentration in North Fork Eagle Creek water samples, in mg/L

1Chloride 

concentration in 

bulk precipitation, 

in mg/L

Mean annual 

precipitation over 

Eagle Creek Basin 

(table 5), in acre-ft

2Chloride 

concentration in 

direct runoff,

in mg/L

Mean annual 

1970–80 direct 

runoff (table 4), 

in acre-ft

Estimated 

recharge, 

in acre-ft

Recharge as a 

percent of 

precipitation

June 12, 2008 7.07 0.33 12,200 0.33 1,440 502 4.1September 6, 2008 7.22 0.33 12,200 0.33 1,440 492 4.0November 17, 2008 7.32 0.33 12,200 0.33 1,440 485 4.0March 18, 2009 7.39 0.33 12,200 0.33 1,440 480 3.9Mean 7.25 0.33 12,200 0.33 1,440 490 4.0

1Average of values reported by Anderholm (1994; 2000), Phillips and others (1984), and Mattick and others (1987).2Assumed to be equal to chloride concentration in bulk precipitation.
Hydrology of North Fork Eagle Creek 29

NATURAL GAMMA,

IN COUNTS PER 

SECOND

SINGLE POINT

RESISTANCE,

IN OHMS

EXPLANATION

STATIC WATER LEVEL—

measured in borehole at the time of geophysical logging,in feet

10 2 10 3 10 4

100150200250300350400450500550600

50

0

6 12 18 50 175 300

NEUTRON,

IN AMERICAN

PETROLEUM

INSTITUTE (API)

 UNITS

0 1,000 2,000

24.00

DEPTH, IN FEET BELOW LAND SURFACE

CALIPER, 

HOLE DIAMETER,

IN INCHES

Figure 8. Borehole geophysical logs for North Fork Eagle Creek borehole MW-1, May 22, 2007, south-central New Mexico.
30 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

MW-4, where oxidation was noted from 60 to 240 ft, abruptly 

terminating near the contact between a light gray and dark 

gray andesite. The light gray zone identified from cuttings 

is noted in gamma logs as a positive shift from 180 to 225 ft 

(fig. 9). The negative shift at the base of this zone corresponds 

with the contact with the underlying dark gray andesite and 

more competent material, as noted on drilling logs, starting 

at 215 ft. The general correspondence of fracture zones and 

oxidized minerals indicates that groundwater flow may be 

stratigraphically influenced by volcaniclastic rock layers with 

differing compositions and differing degrees of fracturing.

The temperature log from MW-4 also indicates that 

groundwater flow may be influenced by fracturing in the 

Sierra Blanca volcaniclastics that is in part stratigraphically 

FLUID

TEMPERATURE, 

IN DEGREES 

FAHRENHEIT

27.83

700

600

500

400

300

200

100

0

800

6 10 14 0 250 500 50 54 58

DEPTH, IN FEET BELOW LAND SURFACE

NATURAL GAMMA,

IN COUNTS PER 

SECOND

CALIPER, 

HOLE DIAMETER,

IN INCHES

EXPLANATION

STATIC WATER LEVEL—

measured in borehole at the 

time of geophysical logging,

in feet

Figure 9. Borehole geophysical logs for North Fork Eagle Creek borehole MW-4, February 18, 2008, south-central New Mexico.

controlled. Fluid-temperature profiles can be used to 

evaluate stratigraphic control in addition to the vertical 

direction of groundwater flow. In general, concave-upward 

temperature profiles denote shallow groundwater movement 

downward into the subsurface. The concave-upward profile 

is produced by the cooling effect of the downward-moving 

groundwater (Bredehoeft and Papadopulos, 1965; Reiter, 

2001). Conversely, groundwater that is warmed at depth and 

moves upward, bringing heat towards the surface, produces a 

concave-downward temperature profile. Similar profiles can 

also be produced by horizontal movement of cool or warm 

groundwater. The temperature profile from MW-4 is concave 

upwards (fig. 9), but it is uncertain whether the concaveupward shape of the temperature log in the interval from 
Hydrology of North Fork Eagle Creek 31

20 to 480 ft is the result of downward flow of cool water or 

horizontal flow of cool water across the entire zone. Below 

480 ft, the temperature log has a linear gradient with depth. 

The negative shift in the gamma log at 480 ft corresponds 

with an andesite compositional change noted as a color 

change from light gray to green in the drill cuttings. The 

correspondence of the compositional change with the onset 

of a geothermal gradient undisturbed by fluid movement 

indicates that vertical flow is retarded by the green-colored 

unit.

ATV logs from MW-4 were used to define the location 

and orientation of fractures intersecting the borehole. MW-4 

is completed to 800 ft in the Sierra Blanca volcaniclastics. 

A total of 275 fractures observed within the borehole were 

mapped and plotted on a Schmidt lower hemisphere equalarea stereoplot (fig. 10). The dips of fractures imaged in MW-4 

range from 2o to 82o to the northwest and southeast with a 

mean of 32o (fig. 11) and a mean strike direction of 33o east of 

north (fig. 10). The dominant fracture orientations generally 

appear to be consistent with surficial mapping of bedding 

in the Ruidoso area (Rawling, 2008). Numerous high-angle 

0°

W 270° 90° E

180°

60

30

Number of points = 275

Mean dip = 32 degrees

Mean strike = 33 degrees

90

N

S

Figure 10. Schmidt lower hemisphere equal-area stereoplot showing orientation of fractures from MW-4 borehole, North Fork Eagle 

Creek, New Mexico. (Concentric circles indicate amount of dip, in degrees, and radial lines indicate compass directions, in degrees.)

cross-strike joints are evident in outcrops along the hill 

slopes of the North Fork, but they are not well represented by 

ATV log analysis. This discordance likely represents sample 

bias because high-angle fractures are not well represented 

in boreholes (Kaehler and Hsieh, 1994). These high-angle 

fractures are likely underrepresented in the present dataset, 

though they may serve an important role to connect strike 

parallel features imaged in MW-4.

Groundwater Levels

Alluvial Wells

Well logs from installation of the alluvial wells indicate 

about 9 to 15 ft of alluvium above a weathered bedrock 

surface (app. 1). MW-1A and MW-2A were completed at or 

above bedrock; MW-3A and MW-5A were completed at 3 

and 5 ft, respectively, into the bedrock. During the study, the 

alluvial wells were generally dry, except when there was flow 

in the North Fork or shortly after heavy rainfall. Through 
32 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

periodic observation it was found that the North Fork stream 

channel was also generally dry from a point between the 

gaging station and the monitoring wells downstream to the 

confluence with the South Fork. The record of water levels 

in these wells from May 2007 through March 2009 is shown 

in figure 12. Water levels were high in late May 2007, at the 

time of instrumentation. In May 2007, 3.71 inches of rain were 

recorded at the Ruidoso climate station, and flow in the stream 

was continuous throughout most of the North Fork channel. 

Channel reaches where flow was intermittent included the 

stream channel adjacent to the well field, which was filled 

with gravel and cobble lag deposits from a previous highflow event, and a downstream reach above where bedrock is 

exposed on the channel bottom.

During May and June 2007, numerous small springs 

at the base of the channel banks contributed to streamflow 

along the downstream length. The elevation of water levels 

in the alluvial wells was higher than the elevation of water in 

the stream channel, indicating that saturated alluvium was in 

connection with the stream channel at this time.

Temperature data collected by the pressure transducers 

indicated a pulse of cold water moving downstream in the 

stream channel and infiltrating into the alluvium successively 

from MW-1A through MW-5A associated with a precipitation 

event (fig. 13). Water temperatures in the deep monitoring 

wells were stable for this same time period. The successive 

downstream temperature pulses in the shallow wells indicate 

that the stream channel serves as a focus for recharge of 

surface runoff to alluvium following intense storms.

Bedrock Wells

The record of water levels in wells MW-1B and MW-1C 

is about 2 years long (fig. 14A); the record for wells MW-4B 

and MW-4C is about 1 year long (fig. 15A). Because of the 

short duration of the groundwater hydrographs, only general 

conclusions can be drawn about the groundwater response 

in the area adjacent to the North Fork wells. Water levels in 

MW-4B and MW-4C varied substantially (by more than 400 

ft in MW-4C, fig. 15A). The rapidly changing water levels 

necessitated frequent manual adjustments of the suspension 

point of the transducers. Water levels sometimes declined 

0

30

60

90

30° 60° 90°

Number of points = 275

Mean dip = 32 degrees

DIP ANGLE, IN DEGREES

COUNT

Depth range 50–800 feet

100

Figure 11. Histogram of fracture dips from MW-4 borehole, North Fork Eagle Creek, New Mexico.
Hydrology of North Fork Eagle Creek 33

7,815

7,820

7,825

7,830

7,835

0

5

10

15

7,780

7,785

7,790

7,795

7,800

0

5

10

15

7,760

7,765

7,770

7,775

7,780

0

5

10

15

7,730

7,735

7,740

7,745

7,750

0

5

10

15

Temperature of water in well or creek

EXPLANATION

Water elevation or discharge Temperature of air in well

WATER ELEVATION, IN FEET ABOVE NAVD 88

TEMPERATURE, IN DEGREES CELSIUS

MW-1A

MW-2A

MW-3A

MW-5A

0.001

0.01

0.1

1

10

100

300

0

5

10

15

DISCHARGE, IN CUBIC

FEET PER SECOND

North Fork Eagle Creek gage

2007

J J A S O N D

2008

J F M A M J J A S O N D J F M September 3, 2008

M

Figure 12. Daily mean surface-water discharge and temperature at the North Fork Eagle Creek gaging station (08387550) in southcentral New Mexico and hourly groundwater elevation and temperature in shallow (alluvial) wells (MW-1A, MW-2A, MW-3A, MW-5A)

(NAVD 88, North American Vertical Datum of 1988). 
34 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

24 25 26 27 28 29 30

December

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

2007

0

5

10

15

MW-1A

MW-2A

MW-3A

MW-5A

DISCHARGE,

IN CUBIC FEET PER SECOND

TEMPERATURE,

IIN DEGREES CELSIUS

-10

0

10

20

30

40

-5

0

5

10

November

TEMPERATURE, IN DEGREES CELSIUS

Blue lines indicate water in well

Red lines indicate no water in well

Discharge

Surface-water temperature

Figure 13. Effect of late November to early December 2007 discharge event at the North Fork Eagle Creek gaging station (08387550), 

south-central New Mexico, on water temperature in alluvial wells (MW-1A, MW-2A, MW-3A, MW-5A).
Hydrology of North Fork Eagle Creek 35

M J J A S O N D J F M A M J J A S O N D J F M

7,000

7,100

7,200

7,300

7,400

7,500

7,600

7,700

7,800

7,900

0

1

2

3

4

5

M J J A S O N D J F M A M J J A S O N D J F M

0

0.5

1

1.5

2

0

0.5

1

1.5

2

2007 2008 2009

2007 2008 2009

PUMPING, IN ACRE-FEET PER DAY

WATER-LEVEL ELEVATION ABOVE NAVD 88 PRECIPITATION, IN INCHES

Elevation of bottom of MW-1B screen

Elevation of

bottom of 

MW-1C screen

A

Missing

data

MW-1B

MW-1C

NF-1 PUMPING

Elevation of land surface

B

Figure 14. A, Daily water-level elevation in monitoring wells MW-1B and MW-1C and pumping from NF-1 production well (NAVD 88, 

North American Vertical Datum of 1988). B, Daily precipitation at Ruidoso, New Mexico, climate station.
36 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

M J J A S O N D J F M A M J J A S O N D J F M

7,000

7,100

7,200

7,300

7,400

7,500

7,600

7,700

7,800

7,900

0

1

2

3

4

5

M J J A S O N D J F M A M J J A S O N D J F M

0

0.5

1

1.5

2

0

0.5

1

1.5

2

2007 2008 2009

2007 2008 2009

MW-4B

MW-4C

NF-4 pumping

WATER-LEVEL ELEVATION ABOVE NAVD 88 PRECIPITATION, IN INCHES

Elevation of bottom of MW-4B screen

Elevation of bottom 

of MW-4C screen

Elevation of land surface

Gaps in hydrograph lines

indicate missing data

A

B

PUMPING, IN ACRE-FEET PER DAY

Figure 15. A, Daily water-level elevation in monitoring wells MW-4B and MW-4C and pumping from NF-4 production well (NAVD 88, 

North American Vertical Datum of 1988). B, Daily precipitation at Ruidoso, New Mexico, climate station.
Hydrology of North Fork Eagle Creek 37

below the level of the transducers between site visits, and 

complete hydrograph records were not obtained for MW-1B, 

MW-4B, or MW-4C.

Two responses are evident in the hydrographs of the 

bedrock wells: an immediate response to pumping in the 

North Fork wells and a longer period fluctuation that likely 

represents a response to regional recharge. Water levels in 

MW-1B and MW-1C declined in response to pumping and 

recovered when pumping ceased, responding both rapidly (as 

in MW-1C for the period beginning September 2008, fig. 14) 

and on a longer frequency time scale (as in the hydrographs 

from May 2007 to March 2008, fig. 14). The response to a 

given fluctuation in pumping rates in the deeper well, MW-1C, 

was greater in magnitude than the response to the same event 

in MW-1B. A similar pattern is seen in the MW-4B and 

MW-4C hydrographs (fig. 15). The pumping rate in NF-4 

was steadier than in NF-1 during the period of observation, 

but response to specific instances of starting and stopping the 

pump can be observed in the MW-4B and MW-4C hydrograph 

record during August through December 2008. As in MW-1B 

and MW-1C, the response to pumping in the deeper well, 

MW-4C, was greater in magnitude for a given event than 

was the response in MW-4B. A longer period fluctuation 

that appears not to be directly related to pumping or discrete 

precipitation events may represent a response to regional 

recharge.

North Fork Eagle Creek Groundwater Response

Water-level data from the monitoring wells were 

supplemented by water-level data from three domestic 

wells upstream from the North Fork well field, which were 

measured during periodic site visits. A longitudinal surface 

profile of the North Fork from a point above the seasonally 

occupied cabins to below the Eagle Creek gaging station is 

shown in figure 16. The relative position along the profile 

of the domestic, monitoring, and production wells is shown, 

along with the depth below land surface of each well. The 

configuration of the water table, based on measurements 

in these wells, is shown for two dates, September 3, 2008, 

and March 17, 2009. The specific dates represent site visits 

to Eagle Creek, during which water levels were measured 

in the domestic wells. No water levels were measured in 

the North Fork wells. September represented a period of 

rising water levels, and March represented a decline. The 

longitudinal profiles indicate drawdown in the water table 

upstream from the North Fork wells. No water levels are 

measured downstream from MW-5A, and the boundary of the 

cone of depression is undefined in the downstream direction. 

Drawdown was deepest in MW-4B, and the water level rose to 

the elevation of the channel bottom just downstream from the 

North Fork gaging station. The water table in the wells above 

the North Fork gaging station was higher than the elevation of 

the channel bottom, and flow in the channel was continuous to 

a point downstream from the gaging station during the period 

of this study.

Discharge at the North Fork gaging station was 1.3 ft3/s 

on September 3, 2008, and 0.15 ft3/s on March 17, 2009. 

Discharge at the Eagle Creek gaging station was similar on 

the two dates (0.19 ft3/s on September 3, 2008, and 0.18 ft3/s 

on March 17, 2009). In March, 2009 the stream channel was 

dry from a point just below DW-3 (see location on fig. 16) 

downstream to immediately above the Eagle Creek gaging 

station. Local residents reported rainfall on September 2, 

2008, and on September 3, 2008, flow was observed in Carlton 

Canyon adjacent to the MW-4 wells (fig. 2). Flow in the North 

Fork was continuous except for the reach between MW-1A 

and MW-5A, where alluvial deposits fill the channel. Water 

levels were about 3 ft above the bedrock-alluvium interface 

(6 ft below land surface) in MW-1A, 7 ft above the bedrockalluvium interface (6 ft below land surface) in MW-3A, and at 

the bedrock-alluvium interface (about 9 ft below land surface) 

in MW-5A. The presence of water in the shallow alluvial 

wells in September 2008, in the area overlying the partial cone 

of depression between MW-1A and MW-5A, indicates that 

the alluvium transmits water downslope above the bedrock 

potentiometric surface in the absence of surface flow in the 

stream channel.

In addition to pumping effects, two major recharge events 

overlie the hydrograph records. In water year 2006 (October 

1, 2005, to September 30, 2006), the annual precipitation at 

Ruidoso of 32.41 inches was 51 percent above the annual 

average of 22.21 inches. The annual precipitation in water 

year 2007 at Ruidoso of 24.15 inches also was above average, 

and 3.72 inches fell in May 2007, at the time that the MW-1 

monitoring wells were being installed. In 2008, storms 

associated with Hurricane Dolly brought heavy precipitation 

to the area. The Sierra Blanca climate station recorded 13.1 

inches of rain in July 2008, most of which fell on July 26 and 

27 and produced the flood of record for many streams in the 

area (U.S. Geological Survey, 2009d).

Water levels in MW-1B and MW-1C were highest on 

May 27, 2007, the first day of data collection (fig. 14). Water 

levels were measured at 16 ft below land surface in MW-1B 

and 20 ft below land surface in MW-1C. North Fork well NF-4 

was not pumping and was flowing under artesian conditions 

at this time. Water levels generally declined through midNovember 2007, with recovery coinciding with a period of no 

pumping in well NF-1. Groundwater hydrographs declined to 

their minimum levels in the summer of 2008. The maximum 

decline in water levels at MW-1B and MW-1C occurred 

between February 14 and June 22, 2008. Water levels in 

February were 22 ft below land surface in MW-1B and 28 ft 

below land surface in MW-1C, with a maximum decline of 

198 ft in MW-1B and 238 ft in MW-1C.

The MW-4B and MW-4C water-level record began 

March 18, 2008 (fig. 15), and may not have captured the 

groundwater maximum, based on comparison to MW-1B and 

MW-1C hydrographs. The highest water levels, on the first 

day of record, were 75 ft below land surface for MW-4B and 

74 ft below land surface for MW-4C. The lowest water level 

elevation, on July 11, 2008, was below the screen depth of 
38 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

7,3007,4007,5007,6007,7007,8007,9008,0008,100

-3,000 -2,000 -1,000 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000

Elevation of bottom of well NF-1 is

7,025 feet above the NA

VD 88 datum

Elevation of bottom of well NF-3 is6,990 feet above the NA

VD 88 datum Elevation of bottom of well NF-4 is 6,782 feet above the NAVD 88 datum

DIST

A

NCE DOW

NSTREA

M FROM

NOR

TH FOR

K EAGLE CREE

K GAGE NEAR ALTO, N. MEX., IN FEE

T

ELEVATION, IN FEET ABOVE NAVD 88

DW-3

DW-2

DW-1

MW-1B

NF-1

MW-2A

NF-3

MW-3A

NF-4

MW-4B

MW-5A

North Fork Eagle Creek

near Alto, N. Mex., gage

Eagle Creek Below South Fork near Alto, N. Mex., gage

Confluence of North and South Fork Eagle Creek

Water levels in bedrock, September 3, 2008

Water levels in bedrock, March 17, 2009

Water levels in alluvium,September 3, 2008(Alluvial wells were dry on March 17, 2009)

MW-1A

Figure 16. Longitudinal profile of North Fork Eagle Creek, New Mexico, showing relative location and depth of monitoring, production, and domestic wells and water levels in alluvium and bedrock on September 3, 2008, and March 17, 2009 (NAVD 88, North American Vertical Datum of 1988). Water levels were not available for wells NF-1, NF-3, and NF-4.
Hydrology of North Fork Eagle Creek 39

MW-4B, which was dry, whereas MW-4C recorded a total 

water-level decline of 438 ft. Water levels began to rise on 

July 11, 2008, for MW-1B and MW-1C (fig. 14) and on July 

15, 2008, for MW-4B and MW-4C (fig. 15). These rises 

did not coincide with precipitation events recorded at the 

Ruidoso climate station or a decline in pumping rates and 

may represent a response to regional groundwater recharge. 

Following the flood of late July, water levels continued to 

rise despite continued pumping from North Fork wells and 

declined in the winter of 2008–09 even though, in the case of 

MW-1B and MW-1C, pumping in NF-1 had ceased. 

The stream channel and underlying alluvium serve 

as a focus for recharge of surface water to groundwater. 

Streamflow collects in the channel through both surface 

runoff and shallow groundwater as base flow, and flow loss is 

measured under some conditions between the North Fork and 

Eagle Creek gaging stations (this topic is discussed further in 

the section “Streamflow Loss in North Fork Eagle Creek”). 

Based on water levels in the bedrock monitoring wells, it was 

determined that the deeper groundwater responds to pumping 

in the North Fork wells, with hydrographs indicating both a 

short-term response to turning pumps on and off and longer 

term declines coinciding with periods of sustained pumping. A 

partial cone of depression is observed in cross-sectional profile 

along the stream channel, extending from MW-4B to upstream 

from MW-1B (fig. 16). The presence of water in the shallow 

alluvial wells in September, in the area overlying the partial 

cone of depression, indicates that the alluvium transmits water 

downslope above the bedrock potentiometric surface in the 

absence of surface flow in the stream channel. A longer period 

fluctuation that appears to be not directly related to either 

precipitation or pumping may represent a response to regional 

recharge.

Chemical Composition of Surface Water and 

Groundwater in Eagle Creek Basin

Major-Ion Chemistry

Surface-water and groundwater chemistry for the study 

area was generally similar among the sites where samples 

were collected (fig. 17). Both surface water and groundwater 

can be characterized as high in calcium relative to other major 

cations, with variability among sites in relative concentrations 

of bicarbonate, sulfate, and chloride. Of note is that water in 

wells MW-1B and MW-1C have similar chemical signatures 

and plot as a single group, whereas water in wells MW-4B and 

MW-4C have distinctly different and more variable chemical 

signatures. South Fork water samples reflect their origin from 

a different basin than do the North Fork water samples in that 

they show the evaporative effects from upstream reservoirs.

The variability of selected constituents among sample 

sites across the four sampling dates is shown in figure 

18A–C. Calcium and sulfate (fig. 18A) increase from lowest 

concentrations in the North Fork and alluvial-well samples 

to progressively higher concentrations in MW-1B , MW-1C, 

Carlton Canyon, MW-4B, NF-1, South Fork, MW-4C and 

NF-4 well samples. Calcium sulfate may indicate interaction 

with evaporite deposits such as gypsum or anhydrite (Hem, 

1985). In the Sacramento Mountains, calcium sulfate in 

surface and groundwater is attributed to interaction with 

gypsum in the Yeso Formation (Rawlings and others, 2008). 

Calcium and bicarbonate concentrations follow a similar 

pattern (fig. 18B), with a higher concentration in the South 

Fork relative to the trend of the samples. Bicarbonate 

concentrations level off in water from MW-4C and NF-4, 

but the calcium concentration continues to increase. Calcium 

bicarbonate concentrations may reflect calcite dissolution 

in the soil or be indicative of water that has interacted with 

carbonate deposits such as limestone or dolomite. The 

lowest concentrations of sodium and chloride were detected 

in the North Fork (fig. 18C) with progressive increases in 

concentration in water from the alluvial wells, MW-1B, 

MW-1C, and production well NF-1. The trend of sodium 

and chloride concentrations differs from the previous two 

sets of constituents because the highest ion concentrations 

were detected in water from MW-4B and the Carlton Canyon 

surface-water sample, with water from MW-4C, NF-4, and 

the South Fork having intermediate concentrations. Increased 

concentrations of chloride may relate to surface evaporation 

of soil moisture or solution of chloride from the rock of 

deep aquifers. The chemical differences among sample sites 

indicate possible differences in source water and flow paths.

Stable Isotopes

Samples were analyzed for the stable isotopes deuterium 

and oxygen-18 (fig. 19). The relative abundance of the heavy 

isotope of hydrogen—deuterium, D—and the heavy isotope of 

oxygen—oxygen-18, 18O—are present in water in a ratio that 

reflects the origin and subsequent history of the water mass 

(Faure, 1977). The ratio of heavy to light isotopes in a water 

mass is expressed as the deviation, in parts per thousand, 

from Standard Mean Ocean Water (Craig, 1961) (δ D and δ 

18O). The Global Meteoric Water Line (GMWL) is a standard 

relation of the deviation of oxygen-18 and the deviation of 

deuterium derived from an average of precipitation samples 

from around the globe (Faure, 1977). In general, more positive 

values (heavier water) are indicative of precipitation in 

warmer regions, during summer, or at lower elevations. More 

negative values (lighter water) are indicative of precipitation 

in colder regions, during winter, or at higher elevations. Local 

climate conditions may result in a Local Meteoric Water Line 

(LMWL) that differs in position from the GMWL. The LMWL 

(fig. 19) is derived from Rawling and others (2008) and is 

based on precipitation collected in the Sacramento Mountains. 

The LMWL lies above the GMWL, and the Eagle Creek data 

fall between these two lines. 

Because of the fairly narrow range over which the Eagle 

Creek data fall, it is difficult to reconcile the sources of water 
40 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

 0 100 

 80 

 60 

 40 

 0 

 20 

 40 

 60 

 80 

 100 0 

 20 

 40 

 60 

 80 

 100 

 0 

 20 

 40 

 60 

 80 

 100 

 100 

 80 

 60 

 40 

 20 

 0 100 

 80 

 60 

 40 

 20 

 0 

 0 

 20 

 40 

 60 

 80 

 100 

 0 

 20 

 40 

 60 

 80 

 100 100 

 80 

 60 

 40 

 20 

 0 

 100 

 80 

 60 

 40 

 20 

 0 

 20 

EXPLANATION

MW-1B, 1C

MW-4B, 4C

Alluvial wells NF-1

NF-4 South Fork Eagle Creek

North Fork Eagle Creek

Carlton Canyon

Calcium (Ca) Chloride (Cl) + Fluoride (F)

Chloride (Cl) + Fluoride (F) + Sulfate (SO4

)

Magnesium (Mg)

Sodium (Na) + Potassium (K)

Bicarbonate (HCO3

) + Carbonate (CO3

)

Calcium (Ca) + Magnesium (Mg)

PERCENT

PERCENT

PERCENT

Sulfate (SO4

)

Figure 17. Trilinear diagram showing hydrochemical-facies classification of major-ion chemistry of surface water and groundwater in 

Eagle Creek Basin, New Mexico, sampled in June, September, and December 2008 and March 2009.
Hydrology of North Fork Eagle Creek 41

0

50

100

150

200

250

300

350

0 20 40 60 80 100 120 140 160 180 200

CALCIUM (Ca) CONCENTRATION, IN MILLIGRAMS PER LITER

20

40

60

80

100

120

140

160

180

200

SULFATE (SO4) CONCENTR

ATION,

IN MILLIGRAMS PER LITER

A

0

0 20 40 60 80 100 120 140 160 180 200

BICARBONATE (HCO3) CONCENTRATION,

IN MILLIGRAMS PER LITER

CALCIUM (Ca) CONCENTRATION, IN MILLIGRAMS PER LITER

B

0

20

40

60

80

100

120

140

0 10 20 30 40 50 60 70 80

CHLORIDE (Cl) CONCENTRATION,

IN MILLIGRAMS PER LITER

SODIUM (Na) CONCENTRATION, IN MILLIGRAMS PER LITER

C

MW-1B

MW-1C

NF-1

NF-4

Alluvial wells

MW-4B

MW-4C

North Fork Eagle Creek

Carlton Canyon

South Fork Eagle Creek

MW-1B

MW-1C

NF-1

NF-4

Alluvial wells

MW-4B

MW-4C

North Fork Eagle Creek

Carlton Canyon

South Fork Eagle Creek

EXPLANATION

Figure 18. Concentrations

of selected constituents 

in surface-water and 

groundwater samples from 

Eagle Creek Basin, New 

Mexico, sampled in June, 

September, and December 

2008 and March 2009. A, 

Calcium and sulfate. B, 

Calcium and bicarbonate. 

C, Sodium and chloride.
42 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

-

-

-

-

-

-

-

74

72

70

68

66

64

62

- 11 - 10 - 9 - 8

Local Meteoric Water Line

June (groundwater)

June (surface water)

September (groundwater)

September (surface water)

November (groundwater)

November (surface water)

March (groundwater)

March (surface water)

Global Meteoric Water Line

-74

-72

-70

-68

-66

-64

-62

-11 -10 -9 -8

δ 18O, IN PARTS PER THOUSAND

MW-1A

MW-1B

MW-1C

MW-3A

MW-4B

MW-4C

MW-5A

NF -1

NF -4

North Fork Eagle Creek

Carlton Canyon

A

B

δ D, IN PARTS PER THOUSAND δ D, IN PARTS PER THOUSAND

δ 18O, IN PARTS PER THOUSAND

Local Meteoric Water Line

Global Meteoric Water Line

EXPLANATION

EXPLANATION

Figure 19. Stable isotopes deuterium (D) and oxygen-18 (18O) expressed as the deviation (δ), in parts per thousand, from Standard 

Mean Ocean Water (Craig, 1961) in surface-water and groundwater samples, North Fork Eagle Creek, New Mexico, June 2008 to March 

2009. A, Data grouped by time of sample collection. B, Data grouped by sample site.
Hydrology of North Fork Eagle Creek 43

or processes that resulted in the observed isotope ratios or 

to develop a mixing model between end-member samples. 

General trends, however, can be noted. 

As with the major-ion concentrations, seasonal trends are 

not evident in the isotope data, but the same general pattern of 

grouping holds, with surface water and alluvial wells having 

the isotopically lightest water, and water from wells NF-4 and 

MW-4C having the isotopically heaviest water with respect to 

oxygen-18. Data for the September 2008 sample date have a 

wider range of isotopic values than do data for the remaining 

three sampling dates because samples were collected from 

four sites that were usually dry. The September 2008 samples 

were collected following 2 days of intense rainfall, after which 

there was flow briefly in Carlton Canyon and groundwater 

in three of the four alluvial wells. September 2008 was the 

only time during the study that the alluvial wells and Carlton 

Canyon could be sampled for stable isotopes. These samples 

are among the isotopically lightest samples collected. The 

Carlton Canyon surface-water sample represents an end 

member of storm runoff and may represent isotopically 

depleted precipitation at the end of several days of intense 

rainfall. The two isotopically heaviest samples, groundwater 

from NF-4 and MW-4C, were both collected in June 2008, 

following 3 months with little rain. These two wells are the 

deepest wells; NF-4 is open to the aquifer to a depth of 1,000 

ft below land surface, and MW-4C is screened at a depth of 

about 800 ft below land surface. A June 2008 water sample 

was not collected at MW-4B because the groundwater level 

was below the 400-ft bottom of the well. 

Similar isotopic signatures in water from the North 

Fork and the alluvial wells reflect the hydrologic connection 

between streamflow and alluvial groundwater. The September 

2008 samples for MW-4B and MW-1C were isotopically 

lighter than all other samples collected from MW-4B and 

MW-1C and were more similar to the signature for the 

surface-water and alluvial-well samples. The September 2008 

signature may indicate a more direct contribution from surface 

water by fracture connectivity in MW-4B and MW-1C, more 

evident following a major recharge event. 

Chlorofluorocarbons 

In attempting to delineate the groundwater-flow system 

in the study area and the effect of pumping on streamflow, the 

question was asked: are the bedrock aquifer and the alluvium 

distinct units, with the municipal groundwater drawing solely 

from an older regional source, or is evidence of recent water 

detectable in the deep monitoring wells? Chlorofluorocarbon 

(CFC) analysis was used to address this question. CFCs 

are gases that were used in refrigeration from the 1930s to 

the 1990s. Atmospheric concentrations of CFCs increased 

from the 1940s through the 1990s to early 2000s, with 

concentrations of all CFC gases constant or declining by 2001. 

The rise and decline of CFC concentrations in the atmosphere 

can be used to estimate the year in which a sample of water 

was last exposed to the atmosphere (Plummer and Busenberg, 

2006). 

CFC age-dating models are based on the concentrations 

of three CFC compounds—CFC-12, CFC-11, and CFC113—and on an assumed groundwater-recharge elevation and 

temperature. Several properties can affect the apparent age 

determined by CFC analysis. Properties potentially affecting 

apparent-age determinations on samples from the North Fork 

study site include recharge temperature and elevation, excess 

air, thickness of the unsaturated zone, microbial degradation, 

mixed water sources, and hydrodynamic dispersion. Table 11

summarizes the environments relevant to this study that are 

most affected by these properties and the associated potential 

errors in apparent-age determination. Further, it is difficult 

to resolve the apparent age of water younger than the 1990s 

when using only CFC concentrations. The use of multiple 

tracers needed for a rigorous analysis of the distribution of 

ages represented by the North Fork suite of water samples 

was beyond the scope of this study. Because of uncertainties 

associated with physical properties and lack of analyses from 

multiple age tracers, apparent CFC ages for these samples are 

approximate. 

In the model used in this analysis, it is assumed that 

groundwater flow after recharge is by piston flow (meaning 

that once the water mass infiltrates into the subsurface, it 

moves through the aquifer with little or no mixing); CFC 

concentrations reflect the initial values of the water mass 

(Plummer and Busenberg, 2009). Groundwater recharge by 

piston flow is the simplest CFC-model assumption, and there 

is insufficient information about the groundwater-flow system 

to support using a more complex model. The piston-flow 

model applies only to the young fraction of the groundwater 

system. Mixing between old (pre-1940) and young (post-1940) 

groundwater is assumed in this analysis. A binary mixing 

model requires that each end member have a single definable 

age (Plummer and others, 2006). The initial age of the older 

water and potential subsequent mixing with younger waters 

are not known, so a binary mixing model is not solvable for 

these samples. A piston-flow model was used to resolve the 

apparent age of young water, and the contribution from old 

water was estimated on the basis of the relative concentration 

of CFCs in the sample compared to the apparent-age 

determination. An appropriate sampling source to characterize 

a potential old-water fraction could not be located.

Water samples were collected in September and 

November 2008 and in March 2009. CFCs were detected in all 

samples. Because sampling protocols (U.S. Geological Survey, 

2009a, b) designed to prevent atmospheric contamination 

were closely followed, some fraction of water in all of the 

monitoring wells appears to have recharged sometime since 

the 1940s when atmospheric CFC concentrations were large 

enough to permit detection.

Data that would have aided in definitively establishing 

recharge temperatures and elevations were not available. 

Reasonable ranges of temperature and elevation for the study 
44 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

Table 11. Summary of properties that can modify apparent age determined by chlorofluorocarbon analysis.

[Table modified from Plummer and Busenberg, 2009; ±, plus or minus; oC, degrees Celsius; ≤, less than or equal to; >, greater than; m, meters; 

CFCs, chlorofluorocarbons]

Property Environment most

affected Description of process Effect on apparent age 

Recharge temperature Shallow water table Temperature at the water table during recharge

Overestimated Too young

Underestimated Too old

± 2°C, ≤1970 ± 1 year or less

± 2°C, 1970-1990 ± 1–3 years

± 2°C, >1990 >3 years

Recharge elevation Mountain recharge Water recharged at high altitude dissolves less CFCs

because of lower barometric pressure

Overestimated Too young

Underestimated Too old

± 100 m not important

± 1000 m, < 1987 ± few years

Significant for post-1990 recharge

Excess air Rapid, focused recharge; 

fractured rock.

Addition of air trapped and dissolved during recharge. 

Significant for post-1990 recharge

Too young

Thickness of 

unsaturated zone

Unsaturated zone >10 m Air in deep unsaturated zone is older than that

of the modern troposphere

0–10 m Too old, error < 2 

years

30 m Too old, error 8–12 

years

Microbial degradation Anaerobic environments, 

sulphate-reducing, 

methanogenic

No degradation in aerobic environments No effect

Sulphate-reducing, and fermentation: CFC-11,

CFC-113 degraded, CFC-12 quasi-stable

CFC-11, CFC-113 

too old

Mixed waters Production wells, 

fractured rock

Mixing of young and older water in water

pumped from open intervals in wells

Apparent age of young fraction in mixture Too old

Apparent age of old fraction in mixture Too young

Hydrodynamic 

dispersion

All groundwater 

environments

Generally small effect for CFCs

1975–1993 Too old

<1975 Too young
Hydrology of North Fork Eagle Creek 45

area were modeled, resulting in a range of possible ages. Two 

likely scenarios for recharge temperature were modeled: (1) 

recharge from summer monsoonal rain or (2) recharge from 

spring snowmelt. The recharge temperature is the air-water 

equilibrium temperature at the time that the groundwater 

sample was isolated from the atmosphere (Cook and 

others, 2006) and is approximated by mean air temperature. 

Weather stations at Cloudcroft (8,710 ft elevation) and Sierra 

Blanca (10,280 ft elevation) were used to estimate recharge 

temperature. For summer monsoonal recharge (June through 

September), mean air temperature at Cloudcroft was 14oC 

(57.2oF) and at Sierra Blanca is 12oC (53.6oF) (Western 

Region Climate Center, 2009). For winter recharge (November 

through February), mean air temperature at Cloudcroft was 

0.56oC (33.0oF) and at Sierra Blanca was -0.16oC (31.7oF). 

Winter recharge was approximated as 1oC (33.8oF). 

Likely scenarios for groundwater recharge elevation are 

(1) recharge from within the watershed, based on an average 

elevation of 8,500 ft for North Fork Eagle Creek Basin, or (2) 

regional groundwater contributions from outside the North 

Fork Basin, such as precipitation recharge to the Sierra Blanca. 

Regional contributions from the Sierra Blanca would include 

elevations higher than those present in Eagle Creek Basin. 

This scenario was evaluated by using an average recharge 

elevation of 10,500 ft. 

Excess air is another variable in the apparent-age 

determination model. Excess air refers to dissolved-gas 

concentrations in groundwater above concentrations that can 

be explained by equilibrium solubility with the atmosphere 

(Cook and others, 2006), and may be due to a transient rise 

in the water table or be artificially introduced during well 

purging. The maximum amount of excess air that can result 

from a rising water table is about 1 cubic centimeter per 

kilogram (cm3/kg) per meter rise in the water table. A value 

of 2 cm3/kg of water is a common assumption (Busenberg 

and Plummer, 2006). A value of 30 cm3/kg is possible 

under extreme conditions such as fractured rock systems in 

mountainous terrains, ephemeral streams in arid regions, and 

infiltration basins (Cook and others, 2006) and may apply to 

the deeper monitoring wells along North Fork Eagle Creek. 

Excess air values of 2 and 30 cm3/kg were evaluated.

Alluvial wells MW-1A, MW-3A, and MW-5A were 

sampled in September 2008. The alluvial wells were dry 

on other sampling dates. Hydrographs from the alluvial 

wells and the North Fork gaging station (fig. 12) indicate 

that the presence of water in the wells was associated with 

storm runoff. The model assumption for these wells was 

that the aquifer was recharged from summer precipitation 

within the basin. An average recharge elevation of 8,500 

ft for the North Fork Basin was used, as well as a recharge 

temperature of 14oC. An excess air value of 2 cm3/kg dates 

the water as originating in the late 1980s or younger. Because 

of the shape of the CFC concentration curves, a unique age 

for water recharged from the 1990s and younger cannot be 

resolved without data from additional tracers. Testing the 

model with a value of 30 cm3/kg excess air at 14oC (57.2oF) 

gives an estimate of recharge date of the mid- to late 1980s. 

If a recharge temperature of 1oC (33.8oF) is used (indicating 

snowmelt runoff), at either 2 or 30 cm3/kg excess air, the 

waters date to the mid-1970s to early 1980s. The presence of 

groundwater in the alluvial wells was associated with storm 

runoff. It is possible that storm water is forcing some older 

water out of the shallow matrix to mix with modern water, 

but the later dates of 2000s to modern water resulting from 

an assumption of 14oC and 2 cm3/kg excess air seem a more 

likely scenario for the alluvial groundwater. The apparent CFC 

age of the young water fraction in the alluvial wells estimated 

by using the piston-flow assumption is 10 years or less. 

For the deep monitoring wells, three parameters were 

varied in the piston-flow model: elevation at 8,500 and 

10,500 ft; temperature at 1o, 12o and 14oC; and excess air at 

2 and 30 cm3/kg. Values for these parameters based on direct 

measurements were not available; the intent was to bracket the 

model parameters within reasonable limits for the flow system 

to delineate a range of probable conditions regarding the 

apparent age of the water. 

Combinations of summer temperatures (12o and 14oC) 

and 2 cm3/kg excess air, at both elevations, were generally not 

able to resolve an apparent age when using the piston-flow 

model. Of the remaining combinations of parameters, apparent 

ages of the young water fraction based on the piston-flow 

model range from the 1970s to modern water, with a large 

percentage, generally 70 to 90 percent, of young (post-1940) 

water in the samples. The apparent CFC age of the young 

water fraction in the deep monitoring wells estimated by using 

the piston-flow assumption is 30 years or less. 

The North Fork wells are completed at depths similar 

to the deep monitoring wells. Based on the analysis of 

apparent CFC ages in the deep monitoring wells, the North 

Fork wells do not draw water solely from an older regional 

groundwater source but are a mixture of young water and 

older groundwater.

Patterns of Surface-Water and Groundwater 

Chemistry

Water-chemistry data are sparse, representing only four 

sample dates over a 12-month period. No consistent seasonal 

trends are evident in the data, but similar groupings are 

observed between sampling sites when comparing a range of 

chemical constituents. 

To better define the relations between sample sites, a 

statistical test (two-sample t-test) was performed on various 

chemical constituents, testing for differences in the means 

of constituent values between groups of samples. The twosample t-test assumes that data from the two groups being 

tested are independent. Group means were tested at a 95 

percent confidence interval, meaning that the probability that 

the group means are significantly different from each other is 

95 percent (Helsel and Hirsch, 2002).
46 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

Na, Cl Mg, Ca, HCO3, SO4, 18O Ca, HCO3, SO4 Ca, SO4, 18O Mg, Ca North Fork

Eagle Creek < alluvialwells < MW-1B

MW-1C < MW-4B < MW-4C < NF-4

Na, Cl > SO4

↑ Cl

Carlton

Canyon

NF-1

<Na, Cl

↑

Figure 20. Trends of chemical constituents in surface-water and groundwater samples from North Fork Eagle Creek, New Mexico, and 

groupings based on significant differences in constituent concentrations.

To increase the size of the sample groups and the 

reliability of the test, sample sites were grouped by following 

observed groupings in the data (figs. 18 and 19). For each 

sample site included in a group, data from all available 

sampling dates for that site were included in the analysis. 

The surface-water sample from Carlton Canyon generally 

is similar to MW-4B in constituent concentrations but is not 

included in this analysis because there is only a single Carlton 

Canyon sample. Significant differences between site groups 

were determined for the constituents calcium, magnesium, 

sodium, chloride, bicarbonate, sulfate, and oxygen-18 (fig. 

20).

The alluvial wells only contained water during the 

September 2008 sampling event; there are no alluvial-well 

samples for the remaining three sampling dates. The alluvial 

wells had a similar chemical signature to the North Fork 

base-flow chemistry (fig. 20), but differed in having higher 

chloride concentrations than the North Fork. The grouping 

of the North Fork and the alluvial wells in figure 20 indicates 

that the two waters are statistically similar for the constituents 

magnesium, calcium, bicarbonate, sulfate, and oxygen-18 but 

that the alluvial wells have statistically greater concentrations 

of sodium and chloride than do the North Fork surface waters. 

Chloride is concentrated in recently precipitated water or in 

shallow groundwater by evapotranspiration (Anderholm, 1994, 

2000). Because the North Fork was sampled at a location 

with perennial streamflow, it would be expected to show less 

evaporative concentration of salts than would groundwater 

from a reach where the alluvium is generally dry and 

undergoes successive wetting, drying, and evapotranspiration 

from seasonal precipitation and runoff.

Carlton Canyon was observed to flow for only a few 

hours following the September 2008 storms and during spring 

runoff. There was also evidence of flow following Hurricane 

Dolly in July 2008. Infrequent surface runoff through the 

shallow colluvium of Carlton Canyon would mobilize 

atmospherically deposited salts that had been evaporatively 

concentrated in the soils, accounting for the higher ion 

concentrations in the Carlton Canyon sample relative to the 

North Fork.

The grouping of samples from Carlton Canyon and 

MW-4B in figure 20 indicates the similarity of these samples 

with respect to major ions (fig. 18), supporting a hydrologic 

connection between MW-4B and the surface. The source 

of high chloride concentrations in water from MW-4B and 

Carlton Canyon, resulting in a general pattern of increasing 

ion concentration among the sample locations that differs from 

the patterns of sulfate and bicarbonate (fig. 18), is not known 

but further supports the hydraulic connection between water 

in MW-4B and the surface. NF-1 groups with MW-4B except 

for sodium and chloride concentrations, which are similar to 

MW-1B and MW-1C. 

The grouping of water from the North Fork and the 

alluvial wells with respect to oxygen-18 supports the concept, 

based on the alluvial hydrographs and CFC data, that the same 

water mass flows through the stream channel and the alluvium. 

Grouping of the Carlton Canyon and MW-4B samples with 

the North Fork and alluvial samples with respect to oxygen-18 

concentrations also supports the MW-4B connection with 

surface water.

Bicarbonate concentrations were significantly higher 

in water from MW-1B and MW-1C than in water from the 

North Fork and the alluvial wells, but the group North Fork, 

alluvial wells, MW-1B, and MW-1C forms a distinct group 

with significantly lower concentrations of bicarbonate than the 

group MW-4B, NF-1, MW-4C, and NF-4 (fig. 20). The same 

pattern holds for sulfate concentrations, but there were further 

significant increases in sulfate concentrations within the 

members of the second group, corresponding to an increase 

in well depth, with sulfate concentrations increasing in water 
Hydrology of North Fork Eagle Creek 47

from MW-4B to MW-4C to NF-4. Increases in bicarbonate 

and sulfate may indicate increases in flow-path lengths (from 

recharge point to the wells) and in transit time of these waters, 

leading to greater rock/water interaction. 

The CFC ratios and major ions, especially bicarbonate 

and sulfate, indicate that the groundwater is a mixture of 

recent (30-year-old and younger) water and older water from 

deeper aquifers. The data indicate three potential groundwater 

influences:

1. Precipitation influence—represented primarily by the 

North Fork and the alluvial wells. Alluvial water recently 

infiltrated into the alluvium, and its composition reflects 

a short flow path and short transit time. The constituent 

composition of this water was similar to water from other 

sampling sites, but constituents generally were present in 

lower concentrations. Chloride concentrations may reflect 

some evapotranspiration history since precipitation, but 

this water has had little opportunity to accumulate a large 

load of less soluble constituents.

2. Calcium bicarbonate influence—represented by water 

from MW-1B and MW-1C. Bicarbonate in groundwater 

may result from dissolution from calcite in the soil, from 

infiltration and evaporation of precipitation, or from 

solution of limestone and dolomite (Hem, 1985) and may 

reflect solution from a deeper aquifer source below the 

volcaniclastics in which the wells are screened. Although 

concentrations of bicarbonate were significantly greater in 

water from MW-4B and MW-4C and the production wells 

than in water from MW-1B and MW-1C (fig. 18B), the 

percentage of bicarbonate relative to sulfate was greater 

in water from MW-1B and MW-1C than in either water 

from the North Fork or MW-4C and the North Fork wells 

(fig. 17).

3. Calcium sulfate influence—represented by water from 

MW-4C and NF-4. Calcium sulfate may be indicative of 

interaction with gypsum and anhydrite deposits (Hem, 

1985) and in the Sacramento Basin is attributed to 

interaction with gypsum in the Yeso Formation (Rawlings 

and others, 2008). Sulfate concentrations increased from 

low concentrations in water from the group composed 

of the North Fork, the alluvial wells, and MW-1B and 

MW-1C to the highest concentrations in MW-4C and 

NF-4. Higher sulfate levels may reflect a longer flow path 

and transit time because these two wells had the highest 

concentrations of all constituents except chloride. Field 

observations and the geophysical logs for the MW-4 

borehole indicate that Carlton Canyon, which intersects 

the North Fork, may represent a major fracture system in 

the area, which could obtain groundwater from a source 

chemically different from that which predominates in 

Eagle Creek. Further sampling under a wider range of 

conditions may better define the sources and processes 

affecting groundwater along the North Fork.

Surface Water

The North Fork and South Fork gaging stations (fig. 

2) were established for this study and as of March 2009 had 

19-month periods of record. The Eagle Creek gaging station 

(fig. 2) was first established on August 27, 1969, about 1,000 

ft downstream from its present location and was maintained 

through December 31, 1980, before being discontinued. The 

Eagle Creek gaging station was reestablished at its present 

location on April 27, 1988, and continues operation to the 

present (2009). The gage was operated in a similar manner 

for both time periods. The change in base flow as a percent 

of average-annual total runoff between the two time periods 

is about 4 percent (table 4). As discussed in the “LongTerm Water Balance – Groundwater Recharge” section, the 

streamflow measurement error is about 7.3 percent, so that 

the potential error in discharge resulting from changing the 

location of the gaging station is within the measurement error. 

The North Fork wells (fig. 2), located about 1.6 mi upstream 

from the present Eagle Creek gaging station location, 

began pumping in 1988. Thus, 1969–80 represents the pregroundwater-pumping period, and 1988–2009 represents the 

groundwater pumping period.

Long-Term Discharge Patterns at Eagle Creek 

Gaging Station

Over the period of record, mean daily discharge at 

the Eagle Creek gaging station increased in response to 

precipitation (fig. 21); however, the pattern of the flow 

response differed between the early (1969–80) and late 

(1989–2009) time periods. The 5-year moving average for 

precipitation at the Ruidoso climate station (fig. 3) indicates 

years of below-average precipitation during both time periods. 

The beginning of the 1970–80 time period is the latter half of 

a 5-year below-average period. The period 1999–2004 was a 

6-year period of below-average precipitation. No days of zero 

flow were recorded for the 11-year period 1970–80. Beginning 

in 1989, however, no-flow days were recorded in 11 of 20 

years, with 8 of the last 10 years having no-flow days. A total 

of 789 no-flow days were recorded from 1989 to March 2009. 

The number of no-flow days within the dry period 1999–2004 

is undoubtedly augmented by decreased precipitation, but 

no-flow days also occurred during periods of above-average 

precipitation and did not occur during periods of belowaverage precipitation during the early period.

Differences in discharge by water year in Eagle Creek 

between 1970–79 and 1989–2008 were tested by using a 

Mann-Whitney ranked nonparametric statistic, which tests for 

differences in the medians of two samples where the data are 

not normally distributed (Helsel and Hirsch, 2002). Results 

of the Mann-Whitney test indicate that the median annual 

discharge is not significantly different between the periods 

1970–79 and 1989–2008 (fig. 22), although data in the earlier 
48 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

0

20

40

60

80

100

120

140

160

180

200

0

5

10

15

20

25

30

35

0

2

4

6

8

10

12

MON

THLY PRECIPIT

A

TION,

IN INCHES

DISCHARGE,

IN CUBIC FEET PER SECOND NUMBER OF NO-FLOW

DAYS PER MON

TH

1969

1970

1975

1980

1985

1990

1995

2000

2005

2008

1969

1970

1975

1980

1985

1990

1995

2000

2005

2008

1969

1970

1975

1980

1985

1990

1995

2000

2005

2008

A

B

C

Figure 21. Precipitation and stream discharge for the period August 28, 1969, to December 31, 2008, in the Eagle Creek Basin, New 

Mexico. A, Monthly precipitation at Ruidoso, New Mexico, climate station. B, Daily mean discharge at the Eagle Creek gaging station 

(08387600). C, Monthly no-flow days at the Eagle Creek gaging station (08387600).
Hydrology of North Fork Eagle Creek 49

600

500

400

300

200

100

0

600

500

400

300

200

100

0

A

B

DISCHARGE, IN CUBIC FEET PER SECOND

EXPLANATION

Median

25th percentile

75th percentile

Highest data value 

within 1.5 times the 

interquartile range

Interquartile range

Outlier

Lowest data value 

within 1.5 times the 

interquartile range

Indicates that the 

median for the 

month during 1970

–80 is significantly 

greater than during

1989–2008 

(95 percent 

confidence interval)

1989–2008

Oct.

Nov.Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

1970–80

Oct.

Nov.Dec.

Jan.

Feb.

Mar.

Apr.

May

June

July

Aug.

Sept.

Figure 22. Median annual and median monthly discharge at the Eagle Creek gaging station (08387600), in south-central New Mexico, 

for the periods A, 1970–79 and B, 1989–2008.
50 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

period are more widely distributed in the higher discharge 

range. Monthly medians for the two periods, however, indicate 

a shift in the pattern of runoff from snowmelt to monsoondominated flow. The median discharge was significantly less, 

at a 95 percent confidence interval, during 1989–2008 than 

during 1970–79 for the months February through May and 

September. During 1989–2008, there was a general flattening 

of the median monthly runoff response. Variability, as well 

as median discharge, was less for February through May 

and September. Variability increased in the upper discharge 

range during the months of June, July, and August when 

compared to 1970–79, although the median monthly values 

were statistically the same for the two periods. Change 

from a snowmelt to a monsoon-dominated flow regime has 

consequences for potential recharge to bedrock from the 

stream channel. Sustained snowmelt runoff provides more 

opportunity to recharge the underlying aquifer, whereas 

monsoonal runoff is of potentially greater magnitude but 

shorter duration, with little opportunity for recharge.

The exceedance probability for flow in Eagle Creek was 

calculated on the basis of the mean daily discharge values 

(Dunne and Leopold, 1978):

, (9)

where

P = the probability, in percentage of time, 

that a given discharge will be equaled or 

exceeded; M = the rank-value of the discharge, in 

descending order; and

= the number of observations for the period.

Exceedance probability was calculated for the 1970–79 

and the 1989–2008 periods, by water year (fig. 23). For 

comparison, the probability discharges for 1979, the 

maximum runoff year for the period of record, and for 2002, 

the minimum runoff year for the period of record, also are 

included. 

The 1970–79 and 1989–2008 exceedance curves are 

similar at the highest discharge values but diverge for the 

remainder of the record, with 1970–79 discharge being 

greater than 1989–2008 discharge for a given probability of 

occurrence (fig. 23). The upper part of exceedance curves 

reflect the way in which high flows or floods move through the 

basin, and the similarity of the upper parts of the exceedance 

curves means that the response of the basin to high-flow 

events has not changed between the two time periods. The flat 

portions of the exceedance curves represent long periods of 

sustained flow such as snowmelt runoff or base flow. In 1979, 

discharge remained greater than about 1 ft3/s over the entire 

0 20 40 60 80 100

10

1

100

0.10

0.01

1979 - Year of maximum runoff for period of record

2002 - Year of lowest runoff for period of record

1989–2008

1970–79

DISCHARGE, IN CUBIC FEET PER SECOND

PERCENT OF TIME INDICATED DISCHARGE WAS EQUALED OR EXCEEDED

 Figure 23. Exceedance probability of discharge at the Eagle Creek gaging station (08387600), in south-central New Mexico, for the 

periods 1970–79 and 1989–2008 and for the years of maximum (1979) and minimum (2002) annual discharge for the period of record.

n
Hydrology of North Fork Eagle Creek 51

water year, and there is little dropoff of the tail of the curve, 

reflecting high base flows in 1979 compared to the combined 

discharge record. For the 1970–79 period, the decline of 

the exceedance curve is steady, dropping off over the upper 

5 percent of the curve but not reaching zero, reflecting the 

capacity of groundwater during this period to sustain base flow 

to the stream.

The 1989–2008 exceedance curve declines more rapidly 

than does the 1970–79 curve (fig. 23), reflecting less available 

sustained base flow than for the earlier period. During the 

dry year of 2002, few observations were made in the flat base 

flow portion of the curve before the tail drops to zero. The 

pattern of the exceedance curve agrees with the observation 

of monsoon-dominated flow during this period (fig. 22) that 

would be expected to provide less shallow groundwater for 

base flow than a snowmelt-dominated system.

Days with zero discharge were included in the calculation 

of exceedance probability. The percent of time a given 

discharge was equaled or exceeded does not accumulate to 

100 percent for the 1989–2008 or the 2002 curves, because 

the zero values are not included in the logarithmic scale of the 

discharge axis but are included in the calculation of values 

(fig. 23). The smallest discharge value recorded by the USGS 

was 0.01 ft3/s, below which discharge is considered to be 

zero. The difference between 100 percent and the maximum 

percentage value of the 1989–2008 and 2002 curves is the 

percentage of each discharge record with zero discharge (no 

flow). In the 2002 water year, the driest year at the Eagle 

Creek gaging station for the entire period of record, zero 

discharge was recorded 34 percent of the time. For the 1989–

2008 period, flow was zero 11 percent of the time.

Factors Affecting Eagle Creek Discharge

Factors affecting the magnitude of discharge in Eagle 

Creek include climate factors such as precipitation and 

evapotranspiration and physical parameters such as drainage 

area, slope, and infiltration capacity of the land surface. The 

change in drainage area caused by moving the gaging station 

1,000 ft upstream to the present location was a decrease of 51 

acres, or 0.1 percent of the total Eagle Creek basin drainage 

area. Changes in the 1969–80 and 1989–2008 discharge 

records because of the decrease in drainage area are negligible. 

Infiltration capacity is affected by changes in land cover 

and land use. The basin is part of U.S. Forest Service land, 

and land cover has not changed appreciably within the time 

period of this study. Groundwater pumping beginning in 

1988 is the only significant change in land and water use over 

this time period (Richard Carlson, U.S. Forest Service, oral 

commun., 2008). The two variables identified as potentially 

affecting the magnitude of stream discharge are precipitation 

and groundwater pumping. Changes in evapotranspiration 

also could affect the magnitude of runoff, but no direct 

measurements are available for this parameter, and it is not 

included in the regression model.

A regression model was fitted to the data from each 

period (1970–79 and 1989–2008) to test whether there was a 

significant difference in the relation between precipitation and 

runoff before the onset of pumping and after pumping began. 

Annual data were used in the regression model to minimize 

the effect of short-term variability. The relation between 

annual precipitation at Ruidoso in inches per water year and 

annual discharge in inches per water year is significantly 

different between 1970–79 and 1989–2008 (fig. 24). Annual 

precipitation is significantly correlated to annual discharge for 

both time periods, but precipitation accounts for 72 percent of 

the variability in the 1970–79 discharge record and 35 percent 

of the variability in the 1989–2008 discharge record. A t-test 

indicated the slopes of the regression lines to be significantly 

different at a 95-percent confidence interval, meaning that the 

relation of precipitation to stream discharge is significantly 

different between the two time periods, and reflecting, at least 

in part, the difference in dominant flow regimes between the 

two time periods. 

Daily pumping records for the North Fork wells were 

provided by the Village of Ruidoso. Regression of the 

pumping record against the 19-month record for the North 

Fork or the 20-year record for Eagle Creek found a small 

but statistically significant correlation (R2 = 10 percent, p < 

0.000) between pumping and discharge when the discharge 

record was lagged 4 months behind the pumping record. This 

correlation indicates that, whereas pumping and streamflow 

are related, any interaction between the two parameters is 

likely to be complex and to involve additional variables and 

processes that have not yet been quantified.

Patterns of Discharge Within Eagle Creek Basin

Monthly discharge at the Eagle Creek, North Fork, and 

South Fork gaging stations and the sum of the discharge at 

the North Fork and South Fork gaging stations are compared 

in figure 25. The data for Eagle Creek in March 2009 and for 

North Fork in August 2008 have 2 weeks of estimated record 

because of repairs to the gaging stations following floods. 

The Eagle Creek record for January and February 2009 was 

affected by ice.

Two floods occurred within the time period of this 

study, a rain-on-snow event on December 1, 2007, and 

floods associated with Hurricane Dolly on July 27, 2008. 

Peak discharges were measured by the slope-area method 

(Dalrymple and Benson, 1968). For the rain-on-snow flood, 

peak discharges at the North Fork and South Fork gaging 

stations were 37 and 38 ft3/s and at the Eagle Creek gaging 

station 80 ft3/s. For Hurricane Dolly, peak discharges at 

the North Fork and South Fork gaging stations were 180 

and 160 ft3/s and at the Eagle Creek gaging station 335 

ft3/s. The hydrographs show an overall decline from the 

peaks associated with these two events over the following 

4–5 months. The hydrograph trends indicate that the two 

precipitation events recharged Eagle Creek Basin and that this 
52 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

15.0 17.5 20.0 22.5 25.0 27.5 30.0

16

14

12

10

8

6

4

2

0

1970–79

1989–2008

1989–2008: R2

 = 35 percent, p = 0.016

1970–79: R2

 = 72 percent, p = 0.001

ANNUAL DISCHARGE, IN INCHES PER WATER YEAR

ANNUAL PRECIPITATION, IN INCHES

EXPLANATION

Figure 24. Regression relations between annual precipitation by water year at Ruidoso, New Mexico, climate station and annual 

discharge by water year at the Eagle Creek gaging station (08387600), in south-central New Mexico, for water years 1970–79 and 

1989–2008.

recharge then discharged as an attenuated base-flow recession 

over the next several months. 

Throughout the study period, the North Fork streambed 

was observed to be mostly dry from below the North Fork 

gaging station to the confluence with the South Fork. At 

times, flow was also observed to completely infiltrate into 

the alluvium in the 400 ft between the South Fork and Eagle 

Creek gaging stations, which is shown by a greater monthly 

discharge at the South Fork gaging station compared to the 

Eagle Creek gaging station for parts of the record. On a daily 

basis, the difference between the South Fork and Eagle Creek 

discharges generally represents a loss of less than 0.1 ft3/s per 

day.

Differences in the patterns of streamflow under 

conditions of partially saturated and unsaturated alluvium are 

seen by comparing discharge at the Eagle Creek gaging station 

to the sum of discharges at the North Fork and South Fork 

gaging stations (fig. 25). If there were no flow loss or gain 

between the upstream and Eagle Creek gaging stations, then 

the sum of discharges at the upstream gaging stations would 

be equal to the discharge at the Eagle Creek gaging station. 

The distance between the North Fork and Eagle Creek gaging 

stations is about 1.6 mi. If the stream gained flow in this reach 

because of surface-water input from side slopes or drainages 

or the accumulation of base flow, then the sum of discharges at 

the upstream gaging stations would be less than the discharge 

at the Eagle Creek gaging station because the additional 

input between the upstream and Eagle Creek gaging stations 

would not be taken into account. The sum of the discharges 

at the upstream gaging stations was equal to or less than the 

discharge at the Eagle Creek gaging station for the period 

July through November 2008, coinciding with the hydrograph 

peaks and recessions following the floods of July 27, 2008. 

The sum of the discharges at the upstream gaging stations 

was also less than the discharge at the Eagle Creek gaging 

station during the flow-loss survey of May 2007, before the 

North Fork and South Fork gaging stations were operating. 

This survey is discussed in the section “Streamflow Loss in 

North Fork Eagle Creek.” Groundwater levels in the alluvial 

wells indicate that July through November 2008 was a period 

of partial saturation of the alluvium (fig. 12). In addition, 

monsoonal rains continued through this period (fig. 14).

The alluvium was also partially saturated in December 

2007 and February 2008 following the December 2007 flood, 

but did not show the persistent partial saturation of the July 

through November 2008 period (fig. 12). The sum of the 

discharges at the upstream gaging stations was greater than 

the discharge at the Eagle Creek gaging station from October 

2007 through June 2008 (fig. 25), indicating flow loss between 

the North Fork and South Fork gaging stations and the Eagle 

Creek gaging station. This loss could be due to infiltration into 

either the alluvium or the underlying bedrock. Observations 
Hydrology of North Fork Eagle Creek 53 0.1

1

10

100

1,000

2007 2008 2009

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

NDOCESREP EETF ICBUC IN ,EGRAH DISCYLH NTOM

Eagle Creek below South ForkNorth Fork Eagle CreekSouth Fork Eagle CreekNorth Fork plus South Fork

Figure 25. Monthly discharge at the Eagle Creek gaging station (08387600), the North Fork gaging station (08387550), the South Fork gaging station (08387575), and the sum of the discharges of the North Fork and South Fork, south-central New Mexico.
54 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

of flow disappearing into the streambed without resurfacing 

at downstream reaches of bedrock channel indicate that some 

component of the streamflow was infiltrating into bedrock.

Streamflow Loss in North Fork Eagle Creek

Flow loss was surveyed between the present location 

of the North Fork gaging station and the Eagle Creek gaging 

station on May 7, 2007, during the period of spring runoff. 

There had been no pumping from the North Fork well field 

for the previous 2 months. Discharge was measured at five 

locations (fig. 26): at the location of the North Fork gaging 

station, between the North Fork well field and MW-5A about 

200 ft downstream from the road crossing, at a location 

about 1,200 ft downstream from MW-5A with some bedrock 

control of the channel, at the location of the South Fork 

gaging station, and at the Eagle Creek gaging station. Two 

locations bracketing a reach of zero flow were also identified. 

Streamflow disappeared beneath the channel bed between the 

locations of NF-1 and NF-3 (fig. 26) and increased in volume 

with distance downstream from the area of no-flow. Overall, 

stream discharge increased as drainage area increased between 

the North Fork and Eagle Creek gaging stations, implying that 

the alluvium was saturated at this time and that downstream 

accumulation from spring runoff and groundwater discharge 

added incrementally to streamflow, characteristic of a gaining 

stream. The sum of the discharges at the present locations of 

the North Fork and South Fork gaging stations was less than 

the discharge at the Eagle Creek gaging station.

The only sustained period of near-continuous flow 

documented during this study occurred in May 2007 when the 

flow-loss survey was conducted. During the survey, when flow 

was largely continuous, reaches persisted where all streamflow 

disappeared beneath the channel bed to reemerge downstream. 

Subsequently, the continuity of flow in the North Fork stream 

channel was established by mapping the appearance and 

disappearance of surface flow downstream from the end of 

perennial flow below the North Fork gaging station to the 

Eagle Creek gaging station (fig. 26). Locations were mapped 

by using a hand-held GPS device at a horizontal resolution of 

±15 ft. Further flow-loss surveys were not feasible because of 

the lack of flow in the channel.

During low-flow periods such as early summer and fall, 

streamflow typically disappeared about 1,600 ft downstream 

from the North Fork gaging station where the channel bottom 

was at bedrock. The North Fork stream channel was dry or 

streamflow surfaced and again disappeared in two or three 

reaches ranging from about 10 to 50 ft long. Streamflow, if 

present, tended to occur in reaches where bedrock outcropped 

in the channel. During dry periods, the South Fork was the 

main contributor to streamflow at the Eagle Creek gaging 

station. 

GPS surveys were completed on eight dates between 

November 2007 and May 2009. Variation in the location of 

the end of perennial flow, expressed as distance downstream 

from the North Fork gaging station, was compared to daily 

average discharge at the gaging station on the date of the 

survey (fig. 27). The sparse data in figure 27 indicate that 

streamflow infiltrates into bedrock in the streambed about 

1,600 ft downstream from the North Fork gaging station. The 

bedrock streambed in this reach appears to have a capacity to 

transmit water downward into the bedrock aquifer at a rate of 

about 0.7–1 ft3/s. At a discharge less than about 0.7–1 ft3/s, 

all water in the North Fork infiltrates into the bedrock, where 

it is available to recharge the bedrock aquifer; at a discharge 

greater than the 0.7–1 ft3/s threshold, streamflow continues 

downstream towards the Eagle Creek gaging station.

The threshold discharge value is consistent with 

calculated estimates by other researchers. Balleau (2004b), 

using the Glover-Balmer equation (Glover and Balmer, 1954), 

estimated streamflow loss in Eagle Creek caused by pumping 

the North Fork wells to be 0.5–0.8 ft3/s. The finite-difference 

groundwater-flow model for the Eagle Creek Basin developed 

by Finch and others (2004) indicates that the North Fork wells, 

pumped at a simulated rate of 0.87 ft3/s, would obtain about 70 

percent of their water (about 0.61 ft3/s) from surface water. 

Assuming that all streamflow below the threshold rate 

of 0.7–1 ft3/s infiltrates the underlying bedrock aquifer, the 

minimum discharge needed to sustain continuous flow in the 

North Fork is the threshold quantity of 0.7–1 ft3/s plus the 

discharge necessary to keep the alluvium saturated to the base 

of the stream channel between the North Fork and the Eagle 

Creek gaging stations.

Conceptual Model of North Fork Eagle Creek 

Hydrology

North Fork Eagle Creek is a perennial stream maintained 

by base flow from groundwater in its upper reaches and 

becoming intermittent in the 2 mi upstream from the Eagle 

Creek gage. Based on the long-term record at the Eagle 

Creek gage, the pattern of runoff shifted between 1970–79 

and 1989–2008 from snowmelt to monsoon-dominated flow, 

reflected in a change from sustained base flow to periods of 

no flow at the Eagle Creek gage. Depending on the position 

of the water table relative to the alluvium and channel bottom, 

sustained snowmelt runoff could provide more opportunity to 

recharge the underlying aquifer, whereas monsoonal runoff is 

of potentially greater magnitude but shorter duration, with less 

opportunity for recharge under similar water-table conditions.

The stream channel and alluvium are underlain by a 

volcaniclastic bedrock aquifer. Groundwater in the aquifer 

shows evidence of a longer flow path or transit time with 

depth. Water from depths equivalent to the North Fork 

production wells is characterized by a large percentage, 

generally 70 to 90 percent, of water aged 30 years or less and 

a small fraction of older regional groundwater. Because of 

differing competencies and degrees of fracturing within the 

volcaniclastics, groundwater is transmitted more readily in a 

horizontal rather than in a vertical direction. When the bedrock 

water table is higher than the bedrock surface, the groundwater 
Hydrology of North Fork Eagle Creek 55

North Fork Eagle Creek

near Alto, N. Mex., gaging station

(08387550)

Eagle Creek below South Fork

near Alto, N. Mex., gaging station

(08387600)

North Fork Eagle Creek

South Fork Eagle Creek Eagle Creek

Forest Road 127A

Route 532

South Fork Eagle Creek

near Alto, N. Mex., gaging station

(08387575)

0

0

0.6

2.41

3.88

2.09

2.33

Flowing reach

Nonflowing reach

South Fork Eagle Creek

near Alto, N. Mex., gaging 

station (08387575)

0.6

EXPLANATION

Streamflow-gaging station 

 and number

MW-5A Monitoring well and name

NF-4 North Fork well and name

Discharge measurement point and 

discharge, in cubic feet per second

NF-1

NF-2

NF-3

NF-4

MW-5A

MW-3A

MW-2A

MW-4B,C

MW-1A,B,C

105°44'30" 105°44'00" 105°43'30"

33°24'30"

33°24'00"

33°23'30"

0 500 1,000 1,500 FEET

0 250 500 METERS

Base from New Mexico Geospatial Data Acquisition Coordination Committee, 2006, 1:12,000

Universal Transverse Mercator projection 

Zone 13

Figure 26. Flowing and nonflowing reaches of North Fork Eagle Creek, New Mexico, May 7, 2007.
56 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

table intersects the alluvium or the stream channel where 

bedrock is at the surface, and contributes to base flow in the 

North Fork. When the bedrock water table has declined below 

the alluvium and channel bottom because of pumping or 

lack of infiltration from the surface, as much as about 1 ft3/s 

of North Fork discharge infiltrates into bedrock about 1,600 

ft downstream from the North Fork gaging station, and the 

remaining discharge infiltrates into the alluvium or continues 

as surface flow. Pumping from the North Fork production 

wells consists of a contribution from streamflow of as much 

as about 1 ft3/s, depending on the available discharge from 

the stream, and an additional contribution from the bedrock 

aquifer.

Alluvial width and thickness between the channel bottom 

and the top of the bedrock aquifer varies between the North 

Fork and Eagle Creek gages. Between the gages, the extent 

and location of channel reaches with surface flow at any 

point in time is a function of the thickness of the saturated 

alluvium in a given reach relative to the channel bottom and 

the magnitude of discharge in the North Fork greater than the 

threshold value of about 1 ft3/s.

Effects of Groundwater Pumping on 

Streamflow

The magnitude of discharge necessary to maintain 

continuous flow in the North Fork is estimated, and the effects 

of pumping in the North Fork well field on streamflow in the 

North Fork are discussed.

Discharge Required To Sustain Continuous Flow 

in North Fork Eagle Creek

The preceding analyses of discharge indicate that a 

portion of streamflow along the North Fork is lost to bedrock 

and the remainder flows downstream within the stream 

channel and the alluvium. Therefore, the total discharge 

needed to sustain flow in the North Fork between the 

North Fork and Eagle Creek gaging stations consists of (1) 

streamflow loss to bedrock, which is the threshold quantity of 

0.7–1.0 ft3/s; (2) streamflow that saturates the alluvium at its 

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

1,000 1,200 1,400 1,600 1,800 2,000 2,200 2,400 2,600

DISTANCE DOWNSTREAM FROM NORTH FORK EAGLE CREEK GAGING STATION, IN FEET

MEAN DAILY DISCHARGE, 

IN CUBIC FEET PER SECOND

09/06/2008

05/13/2009

03/17/2008

11/16/2007

04/30/2008

11/20/2008

02/18/2008

07/23/2008

Figure 27. Distance downstream from North Fork Eagle Creek gaging station (08387550), New Mexico, at which water disappears from 

the stream channel, and mean daily discharge at the gaging station for the dates of measurement.
Effects of Groundwater Pumping on Streamflow 57

greatest cross-sectional area between the North Fork and Eagle 

Creek gages to a thickness that intersects the bottom of the 

stream channel; and (3) additional discharge above the sum of 

(1) and (2), which appears as streamflow in the channel.

The discharge through the alluvium that saturates the 

alluvium at its greatest cross-sectional area to a thickness that 

intersects the bottom of the stream channel was estimated by 

using Darcy’s Law (Freeze and Cherry, 1979):

(10)

where

Q = discharge, in cubic feet per day (converted 

to cubic feet per second for this report); K = hydraulic conductivity, in feet per day; A = cross-sectional area of the alluvium, in 

square feet; and 

i = hydraulic gradient in the alluvium, in feet 

per foot.

 The hydraulic conductivity of sandy gravel has been 

estimated to range from about 280 to 2,800 feet per day (ft/d) 

(0.001 to 0.01 meters per second [m/s] in Freeze and Cherry, 

1979). The cross-sectional area of alluvium was estimated by 

using channel top width measurements obtained by using a 

geographic information system (GIS) and alluvium thickness 

measurements obtained from well-drilling records and an 

elevation survey of the creek channel. Orthophotographs were 

used to delineate valley widths between the North Fork gaging 

station and the Eagle Creek gaging station (fig. 28). Valley 

width at points along the channel was determined by drawing 

lines perpendicular to the active channel from one valley edge 

to the other and measuring the lengths of the lines in a GIS. 

The thickness of the alluvium was determined by using the 

elevation of the bottom of the alluvium from well-drilling 

records and subtracting that elevation from the elevation of the 

nearest channel-elevation survey point. At well MW-5A, the 

elevation of the bottom of the alluvium was higher than the 

elevation of the nearest channel survey point, so the alluvial 

thickness was assumed to be 10 ft at that point. In addition to 

data from well-drilling records, field observations of locations 

where bedrock was exposed in the creek channel were used to 

assign alluvial thickness values of zero. Bedrock was observed 

in the channel at the North Fork gaging station, about 1,200 

ft downstream from well MW-5A, and downstream from 

the road crossing at the Eagle Creek gaging station. Alluvial 

thicknesses between wells and observed bedrock in the 

channel were estimated by subtracting interpolated bedrock 

elevations from channel-elevation survey points. For each 

channel-elevation survey point, the cross-sectional area of the 

alluvium was calculated by assuming a trapezoidal channel 

cross section and a channel side slope of 30o. The hydraulic 

gradient (i) was assumed to be the same as the slope of the 

stream channel. Channel-elevation survey data indicate that 

the average slope of the channel is 0.03 feet per foot.

The North Fork alluvium varies in width and thickness in 

the reach from the North Fork gaging station to the confluence 

of the North and South Forks. The greatest cross-sectional 

area in the reach between the North Fork and Eagle Creek 

gages is located about 100 ft downstream from NF-1. For 

reasonable mid-range values of hydraulic conductivity in 

sandy gravel (500 and 1,000 ft/d), the discharge needed to 

saturate the alluvium to the bottom of the stream channel at 

the location of the greatest cross-sectional area is 0.6 ft3/s 

for a hydraulic conductivity of 500 ft/d and 1.2 ft3/s for a 

hydraulic conductivity of 1,000 ft/d (fig. 29). The observed 

coarse nature of the alluvium would indicate that the actual 

hydraulic conductivity is likely nearer the higher range of 

hydraulic conductivity values, requiring a discharge of 1.2 ft3/s 

to saturate the alluvium to the bottom of the stream channel. 

If it is assumed that water moves continuously downstream 

through the saturated alluvium and that there is negligible 

additional base flow contribution from the sideslopes below 

the North Fork gaging station and negligible additional flow 

loss to the bedrock, then sustained flows greater than 2.2 ft3/s 

(the threshold rate of 1.0 ft3/s, from the Streamflow Loss in 

North fork Eagle Creek section, plus the alluvium saturation 

rate of 1.2 ft3/s) are needed to saturate the alluvium to the 

base of the stream channel and maintain continuous flow 

everywhere along the North Fork channel. In the 19-month 

period of record from September 2007 through March 2009, 

2.2 ft3/s of discharge was equaled or exceeded at the North 

Fork gaging station 2 percent of the time (fig. 30). Although 

the relative contribution of flow from the North Fork and 

South Fork to flow at the Eagle Creek gaging station during 

most of the period of record is unknown, discharge at the 

Eagle Creek gaging station was equal to or greater than 2.2 

ft3/s 22 percent of the time from 1989 to 2008 and was equal 

to or greater than 2.2 ft3/s 39 percent of the time from 1970 to 

1979 (fig. 23).

Effects of Pumping on Continuous Flow in North 

Fork Eagle Creek

No strong correlation is evident between stream discharge 

and pumping for either the 19-month North Fork discharge 

record or the 20-year Eagle Creek discharge record, although 

Eagle Creek discharge, with a 4-month lag period, indicates 

a small but significant correlation to pumping. The Eagle 

Creek record does, however, indicate a change in the pattern 

of flow, with significant decreases in median flow for February 

through May and September from 1989 to 2008 as compared 

to 1970–79 (fig. 22). The change in flow pattern indicates a 

shift from snowmelt-dominated to monsoon-dominated runoff 

and potential changes in the volume of surface-water recharge 

to the bedrock aquifer. Although both the early (1970–79) and 

late (1989–2008) periods had below average precipitation, the 

period 1970–79 had no days without flow. Beginning in 1989, 

no-flow days were recorded in 11 of 20 years, with 8 of the 

last 10 years having no-flow days. (fig. 21). Zero discharge 

,
58 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

0 750 1,500 FEET

0 250 500 METERS

North Fork Eagle Creek 

near Alto, N. Mex., 

gaging station

(08387550)

South Fork Eagle Creek 

near Alto, N. Mex., 

gaging station

(08387575)

Eagle Creek below 

South Fork near Alto, 

N. Mex., gaging station

(08387600) North Fork Eagle Creek

South Fork Eagle Creek

North Fork Eagle Creek Valley

Eagle Creek

EXPLANATION

NF-4 North Fork production well

Streamflow-gaging station and number

South Fork

Eagle Creek

near 

gaging station

Alto, N. Mex.,

(08387575)

NF-1

NF-2

NF-3

NF-4

MW-5A

MW-3A

MW-2A

MW-4B,C

MW-1A,B,C

105° 44' 00" 105° 43' 30"

33° 24' 30"

33° 24' 00"

33° 23' 30"

Base from New Mexico Geospatial Data Acquisition Coordination Committee, 2006, 1:12,000

Universal Transverse Mercator projection 

Zone 13

Figure 28. Delineation of valley widths between the North Fork gaging station and the Eagle Creek gaging station, indicating alluvial fill 

in North Fork Eagle Creek Valley, south-central New Mexico.
Effects of Groundwater Pumping on Streamflow 59

0

0.

1

5

1.

2

5

0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000 11,000

DISTANCE DOWNSTREAM FROM NORTH FORK EAGLE CREEK GAGE, IN FEET

DISCHARGE, IN CUBIC FEET PER SECOND

Confluence of North and South Fork Eagle Creek

Eagle Creek below South Fork near Alto, N. Mex., gage

North Fork Eagle Creek near Alto, N. Mex., gage

Road crossing

Surface water disappears into alluvium

MW-1

NF-1

MW-2

NF-3

MW-3

MW-5

Confluence of North and South Fork Eagle Creek

Carlton Canyon

Culvert under Forest Service road

Bedrock in channel

Discharge needed if hydraulic conductivity of alluvium is 1,000 feet per day

Discharge needed if hydraulic conductivity of alluvium is 500 feet per day

Figure 29. Magnitude of discharge needed to saturate the alluvium of North Fork Eagle Creek, south-central New Mexico, from top of bedrock to bottom of stream channel.
60 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

was recorded for 11 percent of the total discharge record from 

1989 to 2008 (fig. 23).

Based on the previous analyses, the contribution of 

streamflow to the bedrock aquifer in the vicinity of the 

North Fork well field is the discharge threshold of 0.7–1.0 

ft3/s. If the pumping rate is less than or equal to the rate of 

contribution from streamflow, and the water table is below the 

base of the stream channel, then the threshold discharge of 

0.7–1.0 ft3/s will infiltrate into the bedrock aquifer with a net 

recharge of groundwater from surface water. If the bedrock 

aquifer and alluvium are saturated to the base of the stream 

channel, then streamflow will decrease by a rate as much as 

the threshold discharge of 0.7–1.0 ft3/s, corresponding to the 

actual rate of pumping. If the pumping rate is greater than the 

rate of contribution from streamflow, and the water table is 

below the base of the stream channel, then production water 

from pumping will consist of the contribution by streamflow 

up to the threshold quantity (0.7–1.0 ft3/s) plus additional 

groundwater drawn from the bedrock aquifer. Age dating 

indicates that most of this additional groundwater is 30 years 

old or less. This scenario can be quantified by using the 

following system of linear equations:

0 20 40 60 80 100

100.00

10.00

1.00

0.10

0.01

DISCHARGE, IN CUBIC FEET PER SECOND

PERCENT OF TIME INDICATED DISCHARGE WAS EQUALED OR EXCEEDED

Figure 30. Exceedance probability of discharge at North Fork Eagle Creek gaging station (08387550), south-central New Mexico, for 

September 2007 to March 2009.

(11)

,

where

Qd = flow in the North Fork downstream from 

the North Fork well field, in cubic feet per 

second;

Qu = flow in the North Fork upstream from the 

North Fork well field, in cubic feet per 

second;

P = the combined pumping rate, in cubic feet 

per second; and

T = threshold leakage rate (0.7 to 1.0) of 

surface water into the bedrock aquifer, in 

cubic feet per second.

This scenario presents the simple case of no leakage from 

the stream channel in addition to the threshold quantity. In 

fact, additional leakage to the bedrock aquifer would increase 
Summary 61

the contribution of streamflow to groundwater production. 

Equation 11 also does not accurately reflect conditions when 

the pumping rate P is greater than the threshold discharge T

and flow in the North Fork is less than T . When flow in the 

North Fork is less than T, the groundwater contribution to 

North Fork well production would increase. Equation 11 does 

not account for the delay between the time the well pumps 

begin operation and the time that the effects of drawdown in 

the aquifer propagate upward along fractures to the shallow 

alluvium and surface-water system. The delay in propagation 

of the effects of pumping initially would decrease the amount 

of surface water that infiltrates into the bedrock aquifer.

The 19-month record for the North Fork gaging station 

indicates that, even without the North Fork wells pumping, 

streamflow in the North Fork might not be continuous in 

the well-field reach because of the thickness of the alluvium 

and channel deposits. If it is assumed that, without pumping, 

the bedrock aquifer would be saturated to the base of the 

alluvium, then a discharge of only 1.2 ft3/s required to saturate 

the alluvium in its thickest and widest reach would be needed 

to sustain continuous flow in the stream. During the study 

period, a discharge of 1.2 ft3/s was equaled or exceeded 8 

percent of the time (fig. 30). Discharge at the Eagle Creek 

gaging station equaled or exceeded 1.2 ft3/s 32 percent of the 

time during the 1989–2008 period and equaled or exceeded 

1.2 ft3/s 55 percent of the time for the 1970–79 period (fig. 

23). The degree of possible contribution to streamflow from 

the bedrock aquifer when the bedrock aquifer is saturated to 

the base of the alluvium is not known. Given alluvium and 

channel configurations similar to those described in this study, 

however, the exceedance probability for a discharge of 1.2 ft3/s 

at the Eagle Creek gage over the period of record indicates 

that streamflow in some part of the stream channel between 

the North Fork and Eagle Creek gages was discontinuous 

during part of the year during both time periods. Decline of 

the water table in the bedrock aquifer, because of pumping or 

lack of groundwater recharge, would be expected to increase 

the extent and duration of channel reaches with discontinuous 

flow.

Summary

In recent years, urban and resort development and 

drought conditions have placed increasing demands on the 

surface-water and groundwater resources of the Eagle Creek 

Basin, located on the eastern flank of the Sierra Blanca in 

south-central New Mexico. The Village of Ruidoso, New 

Mexico, obtains 60–70 percent of its water from the Eagle 

Creek Basin. The village drilled four production wells (the 

North Fork wells) on Forest Service land along North Fork 

Eagle Creek (the “North Fork”). Three of the four wells were 

put into service in 1988 and remain in use. Local citizens have 

raised questions as to the effects of North Fork well pumping 

on flow in Eagle Creek. In response to these concerns, the U.S. 

Geological Survey, in cooperation with the Village of Ruidoso, 

conducted a hydrologic investigation from 2007 through 2009 

in relation to the potential effect of the North Fork well field 

on streamflow in the North Fork. 

The study area (Eagle Creek Basin upstream from the 

Eagle Creek below South Fork gaging station, the “Eagle 

Creek” gaging station) is located on the eastern flank of the 

Sierra Blanca within the Upper Rio Hondo Basin and about 

2.5 miles (mi) west of Alto, New Mexico. Eagle Creek has 

a drainage area of 8.1 square miles (mi2) above the Eagle 

Creek gaging station and consists of the North Fork Eagle 

Creek (“North Fork”) Basin (5.3 mi2) and the South Fork 

Eagle Creek (“South Fork”) Basin (2.8 mi2). The North Fork 

well field lies within the North Fork basin. The North Fork 

has a narrow, steep drainage. The head of the drainage lies at 

about 10,500 ft elevation. The main valley is characterized 

by forested hill slopes and is dissected by side drainages with 

elevation differences of about 1,300 ft between the ridge tops 

and the streambed. Stream runoff in the North Fork Basin 

occurs predominantly during two periods, the spring snowmelt 

and summer monsoon seasons. Within the study area, the 

North Fork typically is perennial in the upper reaches and, 

depending on streamflow, may be intermittent in about the 

lower 2 mi.

The study area lies within the bounds of the Sierra Blanca 

structural basin, a downfold of sedimentary rocks of Permian 

and Cretaceous ages that are overlain by as much as 3,000 

ft of Tertiary volcanic flows and breccias (volcaniclastics). 

The rocks exposed at land surface within the study area 

consist of volcaniclastic and intrusive rock. Important waterbearing units within the Upper Rio Hondo Basin include 

the volcaniclastics of Tertiary age, the Dakota Sandstone 

of Cretaceous age, and San Andres Limestone and Yeso 

Formation of Permian age. The North Fork wells obtain their 

water from the volcaniclastics. 

The Ruidoso climate station provides the nearest longterm precipitation record from which to extrapolate climate 

information for the Eagle Creek Basin. It is located about 4 mi 

southeast of the Eagle Creek gaging station at an elevation 740 

ft lower than the gaging station. Mean annual precipitation 

for the period of record (1942–2008) at the Ruidoso climate 

station is 22.21 in/yr. Mean monthly precipitation for the 

Ruidoso and Sierra Blanca climate stations indicates that about 

65 and 58 percent, respectively, of annual precipitation falls 

during June through October, with about 39 and 35 percent, 

respectively, falling during July and August.

Precipitation in the Sacramento Mountains is the primary 

source of groundwater recharge. Recharge of precipitation to 

groundwater occurs in part as infiltration through the channel 

bottoms of major and minor drainages and to a lesser extent 

through fractures on rock outcrops. The primary porosity of 

the Sierra Blanca volcaniclastic rocks is low, but porosity has 

been enhanced by later fracturing and faulting.

A long-term (1970–2008) water balance was constructed 

for the study area to provide estimates of the volume of 
62 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

surface water and groundwater discharging from the basin. 

Water-balance components include estimates of base flow 

and direct runoff, precipitation, evapotranspiration, basin 

yield, and groundwater recharge. Basin yield is partitioned 

into estimates of surface-water and groundwater volumes. 

Base-flow analysis indicates that the 1970–80 mean annual 

discharge, direct runoff, and base flow were 2,260, 1,440, and 

819 acre-ft/yr, respectively. Mean annual discharge, direct 

runoff, and base flow for 1989–2008 were 1,290, 871, and 

417 acre-ft/yr, respectively. These results indicate that mean 

annual discharge, direct runoff, and base flow were less during 

the 1989–2008 period than during the 1970–80 period. The 

amount of direct runoff and base flow as a percent of measured 

discharge was similar for the two periods.

The long-term annual precipitation over the study area 

was estimated by using mean annual precipitation values 

and climate-station elevations. Mean annual precipitation 

volumes for the North Fork Eagle Creek Basin, the South Fork 

Eagle Creek Basin, and the Eagle Creek below confluence 

contributing area are estimated to be 8,160, 4,030, and 17.0 

acre-ft, respectively. The mean annual precipitation volume for 

the study area is estimated to be 12,200 acre-ft. 

Evapotranspiration was estimated by using two 

methods: (1) a relation between annual precipitation and 

evapotranspiration based on paired basin studies conducted 

in Colorado and (2) a reference evapotranspiration method.

Estimated annual evapotranspiration for the North Fork 

Eagle Creek Basin and the South Fork Eagle Creek Basin 

calculated by using the relation between annual precipitation 

and evapotranspiration is 5,780 and 2,940, respectively, 

and for the study area is 8,730 acre-ft. Estimated annual 

evapotranspiration for the North Fork Eagle Creek Basin 

and the South Fork Eagle Creek Basin calculated by using 

the reference evapotranspiration method is 5,800 and 3,070 

acre-ft, respectively, and for the study area is 8,890 acre-ft.

Annual basin yield for the North Fork Eagle Creek Basin 

and the South Fork Eagle Creek Basin was estimated as the 

residual of mean annual precipitation minus the average of 

the estimated annual evapotranspiration determined by using 

the two evapotranspiration methods. Estimated annual basin 

yield for the North Fork Eagle Creek Basin and the South Fork 

Eagle Creek Basin was 2,370 and 1,020 acre-ft, respectively, 

and for the entire Eagle Creek Basin above the Eagle Creek 

gaging station was 3,390 acre-ft or about 28 percent of 

precipitation. 

Groundwater recharge was estimated by using two 

methods, a basin yield and a chloride mass-balance method. 

By using the basin-yield method, the annual recharge 

was estimated to be 1,950 acre-ft, or about 16 percent 

of precipitation. Using a chloride mass-balance method, 

groundwater recharge over the study area was estimated to 

average 490 acre-ft (4.0 percent of precipitation). 

During 1970–80, groundwater flow out of the basin 

(1,130 acre-ft) represented about 33 percent of basin yield. For 

the period 1988–2000, groundwater flow out of the basin (552 

acre-ft) was estimated to represent about 16 percent of basin 

yield, and mean annual groundwater pumping (578 acre-ft 

for 1988–2000) was estimated to be about 17 percent of basin 

yield.

Borehole caliper and neutron logs from borehole 

MW-1 show fracture zones from 40 to 90 ft and from 230 

to 310 ft. The two distinct zones of oxidation corroborate 

evidence from continuous water-level measurements that 

indicates that fracture zones at various depths in the borehole 

are hydraulically separated by zones of lower fracture 

permeability. The general correspondence of fracture zones 

and oxidized minerals indicates that groundwater flow may be 

stratigraphically controlled by volcaniclastic rock layers with 

differing compositions and differing degrees of fracturing.

Alluvial well logs indicate about 9 to 15 ft of alluvium 

above a weathered bedrock surface. During the study, the 

alluvial wells were generally dry, except when there was flow 

in the North Fork or shortly after heavy rainfall. Through 

periodic observation it was found that the North Fork stream 

channel was also generally dry from a point between the 

gaging station and the monitoring wells downstream to the 

confluence with the South Fork. Successive downstream 

temperature pulses in the shallow wells associated with a 

precipitation event indicate that the stream channel serves as 

a focus for recharge of surface runoff to alluvium following 

intense storms.

Water levels in MW-4B and MW-4C varied substantially 

(by more than 400 ft in MW-4C). Water-level data from the 

monitoring wells were supplemented by water-level data 

from three domestic wells upstream from the North Fork well 

field, which were measured during periodic site visits. The 

longitudinal profiles indicate drawdown in the water table 

upstream from the North Fork wells. Drawdown was deepest 

in MW-4B, and the water level rose to the elevation of the 

channel bottom just downstream from the North Fork gaging 

station.

Analysis of water levels in the bedrock monitoring wells 

indicated that deeper groundwater responds to pumping in the 

North Fork wells, with hydrographs indicating both a shortterm response to turning pumps on and off and longer term 

declines coinciding with periods of sustained pumping. The 

presence of water in the shallow alluvial wells in September, 

in the area overlying the partial cone of depression, indicates 

that the alluvium transmits water downslope above the 

bedrock potentiometric surface in the absence of surface flow 

in the stream channel. A longer period fluctuation that appears 

to be not directly related to either precipitation or pumping 

may represent a response to regional recharge.

The CFC ratios and major ions, especially bicarbonate 

and sulfate, indicate that the groundwater is a mixture of 

recent (30-year-old and younger) water and older water from 

deeper aquifers. The data indicate three potential groundwater 

influences:

1. Precipitation influence—represented primarily 

by the North Fork and the alluvial wells. Alluvial 

water recently infiltrated into the alluvium, and its 

composition reflects a short flow path and short 

transit time.
Summary 63

2. Calcium bicarbonate influence—represented by 

water from MW-1B and MW-1C. Bicarbonate in 

groundwater may result from dissolution from 

calcite in the soil, from infiltration and evaporation 

of precipitation, or from solution of limestone and 

dolomite and may reflect solution from a deeper 

aquifer source below the volcaniclastics in which the 

wells are screened.

3. Calcium sulfate influence—represented by water 

from MW-4C and NF-4. Calcium sulfate may be 

indicative of interaction with gypsum and anhydrite 

deposits and in the Sacramento Basin is attributed 

to interaction with gypsum in the Yeso Formation. 

Higher sulfate levels may reflect a longer flow path 

and transit time because these two wells had the 

highest concentrations of all constituents except 

chloride.

The North Fork wells began pumping in 1988. Thus, 

1969–80 represents the pre-groundwater-pumping period, and 

1988–2009 represents the groundwater-pumping period. The 

pattern of the flow response in Eagle Creek differed between 

the early (1969–80) and late (1989–2009) time periods. The 

5-year moving average for precipitation at the Ruidoso climate 

station indicates years of below-average precipitation during 

both time periods. No days of zero flow were recorded for the 

11-year period 1970–80. Beginning in 1989, however, no-flow 

days were recorded in 11 of 20 years, with 8 of the last 10 

years having no-flow days. 

Results of the Mann-Whitney test indicate that the 

median annual discharge by water year is not significantly 

different between the periods 1970–79 and 1989–2008, 

although data in the earlier period are more widely distributed 

in the higher discharge range. Monthly medians for the two 

periods, however, indicate a shift in the pattern of runoff 

from snowmelt to monsoon-dominated flow. Change from 

a snowmelt to a monsoon-dominated flow regime has 

consequences for potential recharge to bedrock from the 

stream channel. Sustained snowmelt runoff provides more 

opportunity to recharge the underlying aquifer, whereas 

monsoonal runoff is of potentially greater magnitude but 

shorter duration, with little opportunity for recharge.

The 1970–79 and 1989–2008 exceedance curves are 

similar at the highest discharge values but diverge for the 

remainder of the record, with 1970–79 discharge being 

greater than 1989–2008 discharge for a given probability 

of occurrence. For the 1970–79 period, the decline of the 

exceedance curve is steady, dropping off over the upper 5 

percent of the curve but not reaching zero, reflecting the 

capacity of groundwater during this period to sustain base flow 

to the stream. The 1989–2008 exceedance curve declines more 

rapidly than does the 1970–79 curve, reflecting less available 

sustained base flow than for the earlier period. 

The sum of the discharges at the upstream gaging stations 

was greater than the discharge at the Eagle Creek gaging 

station from October 2007 through June 2008, indicating flow 

loss between the North Fork and South Fork gaging stations 

and the Eagle Creek gaging station. This loss could be due to 

infiltration into either the alluvium or the underlying bedrock. 

Observations of flow disappearing into the streambed without 

resurfacing at downstream reaches of bedrock channel indicate 

that some component of the streamflow was infiltrating into 

bedrock. The only sustained period of near-continuous flow 

documented during this study occurred in May 2007 when the 

flow-loss survey was conducted. During the survey, when flow 

was largely continuous, reaches persisted where all streamflow 

disappeared beneath the channel bed to reemerge downstream. 

During low-flow periods such as early summer and fall, 

streamflow typically disappeared about 1,600 ft downstream 

from the North Fork gaging station.

Variation in the location of the end of perennial flow, 

expressed as distance downstream from the North Fork gaging 

station, was compared to daily average discharge at the gaging 

station on the date of the survey. The sparse data indicate that 

streamflow infiltrates into bedrock in the streambed about 

1,600 ft downstream from the North Fork gaging station. The 

bedrock streambed in this reach appears to have a capacity to 

transmit water downward into the bedrock aquifer at a rate of 

about 0.7–1 ft3/s. At a discharge less than about 0.7–1 ft3/s, 

all water in the North Fork infiltrates into the bedrock, where 

it is available to recharge the bedrock aquifer; at a discharge 

greater than the 0.7–1 ft3/s threshold, streamflow continues 

downstream towards the Eagle Creek gaging station. The 

amount of water needed to saturate the alluvium at its greatest 

cross-sectional area between the North Fork and Eagle Creek 

gages to a thickness that intersects the bottom of the stream 

channel was estimated using Darcy’s law to range from 0.6 

ft3/s to 1.2 ft3/s. If it is assumed that water moves continuously 

downstream through the saturated alluvium and that there 

is negligible additional base-flow contribution from the 

sideslopes and negligible additional flow loss to the bedrock 

below the North Fork gaging station, then sustained flows 

greater than 2.2 ft3/s are needed to saturate the alluvium and 

maintain continuous flow in the North Fork. In the 19-month 

period of record from September 2007 through March 2009, 

2.2 ft3/s of discharge was equaled or exceeded at the North 

Fork gaging station 2 percent of the time.

If it is assumed that, without pumping, the bedrock 

aquifer would be saturated to the base of the alluvium, then 

a discharge of only 1.2 ft3/s required to saturate the alluvium 

in its thickest and widest reach would be needed to sustain 

continuous flow in the stream. During the study period, a 

discharge of 1.2 ft3/s was equaled or exceeded at the North 

Fork gaging station 8 percent of the time. Discharge at the 

Eagle Creek gaging station equaled or exceeded 1.2 ft3/s 32 

percent of the time during the 1989–2008 period and equaled 

or exceeded 1.2 ft3/s 55 percent of the time for the 1970–79 

period. Given alluvium and channel configurations similar to 

those described in this study, streamflow in some part of the 

stream channel between the North Fork and Eagle Creek gages 

was likely discontinuous during part of the year during both 

time periods.
64 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

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68 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

Appendix 1. Well-completion details for monitoring wells MW-1A, MW-1B, MW-1C, MW-2A, 

MW-3A, MW-4B, MW-4C, and MW-5A near North Fork Eagle Creek, New Mexico.

Land surface

15 ft - bottom of screen and top 

of sump (2.5-in. schedule 80 

flush-threaded polyvinyl chloride)

20 ft - bottom of sump and borehole

Bedrock

Alluvium

2-ft × 2-ft × 4-in.-thick concrete pad

3-ft × 6-in. steel wellhead protector 

with locking cap 2-in. expandable locking well cap

0

5

10

15

20

MW-1A

6-in.-diameter borehole

DEPTH BELOW LAND SURFACE, IN FEET

 HORIZONTAL SCALE IS EXAGGERATED

Top of casing (2.5-in. schedule 

80 flush-threaded polyvinyl chloride)

0 ft - top of bentonite chips (3/8 in.)

5 ft - top of 0.010-in. slot screen 

(2.5-in. schedule 80 flush-threaded 

polyvinyl chloride)

4 ft - top of sand (8/12 silica sand)

Figure 1–1. Completion 

diagram of monitoring well 

MW-1A, near North Fork 

Eagle Creek, New Mexico.
Appendix 1 69

595 ft - bottom of MW-1C sump

590 ft - top of MW-1C sump and bottom of MW-1C stainless steel screen

580 ft - top of MW-1C stainless steel 0.010-in. slot screen

563 ft - top of MW-1C sand pack (8/12 grade)

523 ft - top of bentonite pellets

Bentonite chips

347 ft - bottom of MW-1B 0.010-in. slot screen and top of sump

337 ft - top of MW-1B stainless steel screen 

300 ft - top of MW-1B sand pack

285 ft - top of bentonite pellets

Bentonite chips

31 ft - bottom of surface casing 

610 ft - bottom of borehole

352 ft - bottom of MW-1B sump

Land surface

2-ft × 2-ft × 4-in.-thick concrete pad

8-in.-diameter

borehole (0 to 575 ft 

below land surface)

3-ft × 10-in. steel wellhead protector 

with locking cap

 2-in. expandable locking well caps

0

50

100

150

200

250

300

350

400

450

500

550

600

Alluvium

Bedrock

DEPTH BELOW LAND SURFACE, IN FEET

Top of polyvinyl chloride well casing

6.75-in.-diameter borehole 

(575 to 610 ft below land 

surface)

MW-1B and MW-1C

 HORIZONTAL SCALE IS EXAGGERATED

2.5-in. schedule 80 flush-threaded polyvinyl chloride casing

365 ft - top of bentonite chips (3/8 in.)

Land surface - top of MW-1B bentonite chips (3/8 in.)

Top of surface casing (8-in. steel)

Figure 1–2. Completion diagram of monitoring wells MW-1B and MW-1C, near North Fork Eagle Creek, New Mexico.
70 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

5 ft - top of 0.010-in. slot screen 

(2.5-in. schedule 80 flush-threaded polyvinyl chloride)

Land surface

Top of casing (2.5-in. schedule 

80 flush-threaded polyvinyl chloride)

15 ft - top of sump and bottom of screen 

(2.5-in. schedule 80 flush-threaded polyvinyl chloride)

20.5 ft - bottom of sump and borehole

Bedrock

Alluvium

4 ft - top of sand (8/12 silica sand)

0 ft - top of bentonite chips (3/8 in.)

2-ft × 2-ft × 4-in.-thick concrete pad

3-ft × 6-in. steel wellhead protector 

with locking cap 2-in. expandable locking well cap

HORIZONTAL SCALE IS EXAGGERATED

16 ft - top of bedrock

0

5

10

15

20

DEPTH BELOW LAND SURFACE, IN FEET

MW-2A

6-in.-diameter borehole

Figure 1–3. Completion diagram of monitoring well MW-2A, near North Fork Eagle Creek, New Mexico.
Appendix 1 71

6 ft - top of 0.010-in. slot screen 

(2.5-in. schedule 80 flush-threaded polyvinyl chloride)

Land surface

Top of casing (2.5-in. schedule 

80 flush-threaded polyvinyl chloride)

16 ft - bottom of screen and borehole

Bedrock

Alluvium

5 ft - top of sand (8/12 silica sand)

0 ft - top of bentonite chips (3/8 in.)

2-ft × 2-ft × 4-in.-thick concrete pad

3-ft × 6-in. steel wellhead protector

with locking cap 2-in. expandable locking well cap

5

0

10

15

 HORIZONTAL SCALE IS EXAGGERATED

13 ft - top of bedrock

DEPTH BELOW LAND SURFACE, IN FEET

MW-3A

6-in.-diameter borehole

Figure 1–4. Completion diagram of monitoring well MW-3A, near North Fork Eagle Creek, New Mexico.
72 Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009

50

100

200

250

300

350

400

450

500

550

600

650

700

750

800

150

802 ft - bottom of borehole

797 ft - bottom of MW-4C stainless steel sump

787 ft - bottom of MW-4C stainless steel screen

777 ft - top of MW-4C stainless steel 0.010-in. slot screen

740 ft - top of sand (10/20 grade)

689 ft - top of bentonite pellets (1/4 in.)

411 ft - top of bentonite chips (3/8 in.)

317 ft - top of sand (10/20 grade)

284 ft - top of bentonite pellets (1/4 in.) 

Land surface - top of MW-4B bentonite chips (3/8 in.)

390 ft - top of MW-4B stainless steel 0.010-in. slot screen

400 ft - bottom of MW-4B stainless steel screen

410 ft - bottom of MW-4B sump

2.5-in. schedule 80 flush-threaded polyvinyl chloride casing

MW-4B and MW - 4C

 HORIZONTAL SCALE IS EXAGGERATED

DEPTH BELOW LAND SURFACE, IN FEET

Bentonite chips

8-in.-diameter

borehole (0 to 720 ft 

below land surface)

6.75-in.-diameter

borehole (720 to 804 ft 

below land surface)

40 ft - bottom of surface casing 

Land surface

2-ft × 2-ft × 4-in.-thick concrete pad

3-ft × 10-in. steel wellhead protector 

with locking cap 2-in. expandable locking well caps

Alluvium

Bedrock

Top of surface casing (8-in. steel)

Top of polyvinyl chloride well casing

Figure 1–5. Completion 

diagram of monitoring 

wells MW-4B and MW-4C, 

near North Fork Eagle 

Creek, New Mexico.
Appendix 1 73

4 ft - top of 0.010-in. slot screen 

(2.5-in. schedule 80 flush-threaded polyvinyl chloride)

Land surface

Top of casing (2.5-in. schedule 

80 flush-threaded polyvinyl chloride)

14 ft - bottom of screen and borehole

Bedrock

Alluvium

3 ft - top of sand (8/12 silica sand)

0 ft - top of bentonite chips (3/8 in.)

2-ft × 2-ft × 4-in.-thick concrete pad

3-ft × 6-in. steel wellhead protector 

with locking cap 2-in. expandable locking well cap

 HORIZONTAL SCALE IS EXAGGERATED

9 ft - top of bedrock

0

5

10

15

DEPTH BELOW LAND SURFACE, IN FEET

MW-5A

6-in.-diameter borehole

Figure 1–6. Completion diagram of monitoring well MW-5A, near North Fork Eagle Creek, New Mexico.
Prepared by the USGS Lafayette Publishing Service Center
Matherne, Myers, and McCoy—Hydrology of Eagle Creek Basin and Effects of Groundwater Pumping on Streamflow, 1969–2009—SIR 2010–5205

Printed on recycled paper

I SBN 9 78 - 1 - 4 11 3- 30 13 -9

9 78 1 4 1 1 3 3 0 1 39