Hydrologic Conditions and Assessment

of Water Resources in the Turkey Creek

Watershed, Jefferson County, Colorado,

1998–2001

By Clifford R. Bossong, Jonathan Saul Caine, David I. Stannard,

Jennifer L. Flynn, Michael R. Stevens, and Janet S. Heiny-Dash

Denver, Colorado

2003

Prepared in cooperation with the

JEFFERSON COUNTY PLANNING AND ZONING DEPARTMENT

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 03–4034
District Chief

U.S. Geological Survey

Box 25046, Mail Stop 415

Denver Federal Center

Denver, CO 80225–0046

For additional information write to:

District Chief

U.S. Geological Survey

Box 25046, Mail Stop 415

Denver Federal Center

Denver, CO 80225–0046

U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

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

not constitute endorsement by the U.S. Geological Survey.

Copies of this report can be purchased 

from:

U.S. Geological Survey

Information Services

Box 25286

Denver Federal Center

Denver, CO 80225
CONTENTS III

Glossary of Special Terms ..................................................................................................................................................... IX

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

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

Purpose and Scope....................................................................................................................................................... 3

Location and Setting .................................................................................................................................................... 3

Previous Investigations ................................................................................................................................................ 3

Acknowledgments ....................................................................................................................................................... 3

Geologic Framework ............................................................................................................................................................. 5

Data Collection and Methods ................................................................................................................................................ 9

Historical Data ............................................................................................................................................................. 9

Contemporary Data...................................................................................................................................................... 13

Fracture Characteristics ..................................................................................................................................... 13

Outcrop Selection .................................................................................................................................... 14

Methods of Fracture Measurement.......................................................................................................... 14

Climatologic Data.............................................................................................................................................. 14

Surface-Water Data............................................................................................................................................ 20

Ground-Water Data............................................................................................................................................ 20

Water-Quality Data ............................................................................................................................................ 21

Runoff Modeling Methods........................................................................................................................................... 27

General Characteristics of the Precipitation-Runoff Modeling System ............................................................ 29

Watershed Characterization Using the Precipitation-Runoff Modeling System ............................................... 30

Hydrologic Conditions........................................................................................................................................................... 32

Evapotranspiration ....................................................................................................................................................... 32

Forest Site Results ............................................................................................................................................. 32

Meadow Site and Comparison to Forest Site..................................................................................................... 40

Surface-Water Conditions............................................................................................................................................ 46

Watershed Conditions ........................................................................................................................................ 46

Intrawatershed Conditions ................................................................................................................................. 48

Ground-Water Conditions............................................................................................................................................ 51

Time-Series Water Levels.................................................................................................................................. 51

Synoptic Water Levels ....................................................................................................................................... 57

Analysis of State Engineer Well-Construction Data.......................................................................................... 58

Univariate Statistics ................................................................................................................................. 58

Variogram Analysis ................................................................................................................................. 61

Water-Quality Characteristics in the Turkey Creek Watershed ................................................................................... 63

General Water-Quality Characteristics .............................................................................................................. 63

Comparison to Historical Water-Quality Data................................................................................................... 72

Tritium ............................................................................................................................................................... 73

Chloride to Bromide Ratios ............................................................................................................................... 74

Wastewater Compounds..................................................................................................................................... 75

Chloride Sources................................................................................................................................................ 76

Seasonality of Specific Conductance................................................................................................................. 77

Assessment of Water Resources ............................................................................................................................................ 79

Estimates of Potential Fracture-Network Porosity ...................................................................................................... 79

Runoff Modeling.......................................................................................................................................................... 83

Hydrologic Response Unit Delineation and Parameterization .......................................................................... 83

Interflow and Base-Flow Reservoir Delineation and Parameterization............................................................. 88

Distribution of Precipitation and Temperature Data.......................................................................................... 89

Model Calibration.............................................................................................................................................. 90

Watershed Calibration Procedures........................................................................................................... 91

Intrawatershed Calibration Procedures.................................................................................................... 92

Final Calibration ...................................................................................................................................... 92

CONTENTS
IV CONTENTS

Contemporary Simulations................................................................................................................................ 92

Long-Term Simulations..................................................................................................................................... 102

Simulation Results and Their Implications to Water Supply ............................................................................ 106

Summary................................................................................................................................................................................ 117

Selected References............................................................................................................................................................... 120

Appendix ............................................................................................................................................................................... 125

Brittle Structures of the Turkey Creek Watershed....................................................................................................... 127

Fracture Data Analysis, Model Construction, and Matching Models to Data ............................................................ 128

Fracture Set Designation ................................................................................................................................... 129

Fracture Length Simulation............................................................................................................................... 130

Fracture Spacing................................................................................................................................................ 130

Fracture Intensity and Calibration of Fracture Network Models to Field Data................................................. 130

Spatial Analysis of Well-Construction Data and Ground-Water Levels ..................................................................... 131

Evapotranspiration Measurement Methods ................................................................................................................. 132

Quality Assurance and Quality Control....................................................................................................................... 134

Milliequivalent Balances ................................................................................................................................... 134

Quality-Control Samples ................................................................................................................................... 135

Duplicate Samples ............................................................................................................................................. 137

FIGURES

1–8. Maps showing:

1. Location of Turkey Creek watershed in Jefferson County, Colorado; identifier and locations for 

sites with specific-conductance measurement; and location of Bailey, Cheesman, and Elk Creek 

climatologic monitoring stations.................................................................................................................... 4

2. Compilation of parts of the existing Evergreen, Indian Hills, Morrison, Conifer, and Meridian 

Hills U.S. Geological Survey Geologic Quadrangle Maps ............................................................................ 6

3. Simplified geologic map, locations of outcrops where fracture characteristics were measured 

or observed, and fracture-orientation data for measurements at each location .............................................. 7

4. Locations of surface-water streamflow measurement and sampling sites, stream gages, and 

irrigation ditches............................................................................................................................................. 11

5. Locations of permitted wells from the State Engineers Office ...................................................................... 12

6. Spatial distribution of water-quality samples collected in previous studies in the Turkey Creek 

watershed........................................................................................................................................................ 13

7. Location of climatologic monitoring sites ..................................................................................................... 15

8. Schematic of the energy balance of a vegetated surface ................................................................................ 16

9. Photograph of eddy-correlation evapotranspiration tower at forest site................................................................. 19

10. Photograph of Bowen-ratio evapotranspiration tripod at meadow site .................................................................. 21

11. Map showing locations of water-level monitoring wells ....................................................................................... 23

12. Map showing location of ground-water sampling sites.......................................................................................... 27

13. Schematic diagram of selected physical processes characterized by Precipitation-Runoff Modeling 

System .................................................................................................................................................................... 31

14–22. Graphs showing:

14. Daily evapotranspiration at forest site during (A) 1999, (B) 2000, and (C) 2001.......................................... 33

15. Daily precipitation and daily mean soil moisture at forest site during (A) 1999, (B) 2000, and 

(C) 2001 ......................................................................................................................................................... 34

16. Daily mean solar radiation at forest site during (A) 1999, (B) 2000, and (C) 2001....................................... 35

17. Annual precipitation and infiltration at forest site during the study period................................................... 38

18. Daily precipitation and cumulative infiltration at forest site during (A) 1999, (B) 2000, and 

(C) 2001 ......................................................................................................................................................... 39

19. Daily evapotranspiration at meadow and forest sites during (A) 2000 and (B) 2001 .................................... 41

20. Daily precipitation at meadow site, and daily mean soil moisture at meadow and forest sites 

during (A) 2000 and (B) 2001 ........................................................................................................................ 42

21. Daily mean solar radiation at meadow site during (A) 2000 and (B) 2001.................................................... 43

22. Streamflow hydrographs for the three stream gages on Turkey Creek and annual precipitation 

at the Cheesman site ...................................................................................................................................... 47
CONTENTS V

23. Map showing locations of short-term record stream gages and sites of synoptic streamflow 

measurements......................................................................................................................................................... 51

24. Hydrographs from short-term records of streamflow (A, log; B, arithmetic) ........................................................ 52

25–29. Graphs showing:

25. Ground-water fluctuations in water-level monitoring wells.......................................................................... 54

26. Ground-water table in the Turkey Creek watershed, September 2001.......................................................... 58

27. Contours of depth to ground water for September 2001 ............................................................................... 59

28. Well yield and total depth for State Engineers Office permitted wells ......................................................... 63

29. Variogram surface maps ................................................................................................................................ 64

30. Stiff diagrams of selected water-quality constituents in the Turkey Creek watershed .......................................... 69

31. Trilinear diagram of quarterly ground-water and surface-water samples collected in the Turkey 

Creek watershed..................................................................................................................................................... 70

32–35. Maps showing:

32. Specific-conductance measurements in ground- and surface-water samples................................................ 71

33. Concentrations of chloride in ground- and surface-water samples ............................................................... 72

34. Concentrations of nitrate plus nitrite in ground- and surface-water sample.................................................. 73

35. Concentrations of boron in ground- and surface-water samples ................................................................... 74

36–38. Graphs showing:

36. Plot of tritium concentrations in precipitation interpolated to Turkey Creek watershed 

location and decayed to year 2000 values, and boxplot of tritium concentrations in selected 

water wells in the Turkey Creek watershed................................................................................................... 75

37. Time-series plot of Turkey Creek watershed hydrologic variables and seasonal specificconductance measurements collected at selected wells in fall 2000 and spring 2001 .................................. 78

38. Correlation of specific conductance and streamflow and time-series plot showing seasonal 

variation of specific conductance and streamflow at Turkey Creek at mouth of canyon near 

Morrison ........................................................................................................................................................ 80

39. Boxplot showing distribution of specific conductance at Turkey Creek at mouth of canyon (site A)

and six comparison sites ........................................................................................................................................ 82

40. Graph showing plot of the log of total fracture model potential porosity for each locality................................... 83

41. Map showing Hydrologic Response Units delineated for use with the Precipitation-Runoff 

Modeling System in the Turkey Creek watershed ................................................................................................. 85

42. Map showing interflow and base-flow reservoirs delineated for use with the Precipitation-Runoff 

Modeling System in the Turkey Creek watershed ................................................................................................. 89

43–45. Graphs showing:

43. Watershed hydrographs of contemporary simulated and measured results................................................... 93

44. Intrawatershed hydrographs of contemporary simulated and measured results............................................ 96

45. Watershed hydrographs of long-term simulated results ................................................................................ 107

APPENDIX FIGURE

A1. Flow chart showing how discrete fracture-network model parameters are modeled to lead to the 

construction of a single best-fit model................................................................................................................... 129

TABLES

1. Individual rock types assigned to rock groups in the Turkey Creek watershed...................................................... 8

2. List of sites with time-series records ...................................................................................................................... 10

3. Univariate statistics for water-quality properties and constituents collected in previous studies........................... 14

4. Sensor type, data loggers, sensor heights, and measured variables at forest site ................................................... 18

5. Sensor type, heights, and measured variables at meadow site................................................................................ 20

6. Site identifiers and selected characteristics for sites of surface-water-quality samples, short-term 

streamflow records, and synoptic streamflow measurements in the Turkey Creek watershed, Jefferson 

County, Colorado, 1998–2001 ................................................................................................................................ 22

7. Well-construction details and miscellaneous data for ground-water level monitoring wells in the Turkey 

Creek watershed, Jefferson County, Colorado, 1998–2001................................................................................... 24
VI CONTENTS

8. Site identifiers and selected characteristics for ground-water-quality sampling sites in the Turkey Creek 

watershed, Jefferson County, Colorado, 1998–2000............................................................................................... 25

9. Water-quality properties and constituents included in analyses in water year 1999............................................... 28

10. Miscellaneous data collected in water year 2001, including analysis results for bromide, selected inorganic 

ions, wastewater compounds, and tritium ............................................................................................................... 29

11. Climatic and water balance summary for calendar years 1999, 2000, 2001, and 3-year mean, at forest site ........ 36

12. Climatic and water balance summary for calendar year 2001 at meadow and forest sites..................................... 44

13. Streamflow statistics for Turkey Creek................................................................................................................... 49

14. Measured precipitation and streamflow in and near the Turkey Creek watershed ................................................. 50

15. Synoptic measurements of streamflow made at rock group sites and surface-water sampling sites ...................... 53

16. Univariate statistics and correlations for well-construction characteristics ............................................................ 60

17. Descriptive statistics for selected physical characteristics of permitted wells from the State Engineers 

Office, by rock group .............................................................................................................................................. 61

18. Univariate statistics for reported well yields by rock type and group and through time ........................................ 62

19. Univariate statistics for water-quality properties and constituents in selected ground-water samples 

collected September 1998 through November 1999............................................................................................... 65

20. Univariate statistics for water-quality properties and constituents in selected surface-water samples 

collected September 1998 through November 1999............................................................................................... 67

21. Specific-conductance data summary for Turkey Creek at mouth (site A) and eight comparison sites 

on the eastern slope of the Rocky Mountains in Colorado ..................................................................................... 81

22. Turkey Creek watershed hydrologic parameter estimates from previous work...................................................... 82

23. Turkey Creek watershed fracture-model potential porosity results ........................................................................ 84

24. Summary of Hydrologic Response Unit and base-flow reservoir characteristics, and hydrologic 

response unit accounting for contemporary simulation in the Turkey Creek watershed ........................................ 86

25. Monthly means and selected summary statistics for measured precipitation ......................................................... 90

26. Watershed and intrawatershed calibration statistics................................................................................................ 95

27. Monthly and annual summary statistics for contemporary simulations (January 1, 1999, through 

September 30, 2001) for the entire Turkey Creek watershed.................................................................................. 97

28. Intrawatershed summary statistics for contemporary simulations (January 1, 1999, through 

September 30, 2001) for areas of (A) metamorphic, (B) intrusive, and (C) fault-zone rocks and 

(D) Pikes Peak Granite............................................................................................................................................ 98

29. Summary statistics of daily values for water-balance terms from contemporary simulations in (A) the

entire Turkey Creek watershed and for areas of (B) metamorphic, (C) intrusive, and (D) fault-zone rocks

and (E) Pikes Peak Granite ..................................................................................................................................... 102

30. Annual summary statistics for long-term simulations (October 1, 1948, through September 30, 1999) 

in the entire Turkey Creek watershed...................................................................................................................... 108

31. Intrawatershed summary statistics for long-term simulations (October 1, 1948, through 

September 30, 1999) for areas of (A) metamorphic, (B) intrusive , and (C) fault-zone 

rocks and (D) Pikes Peak Granite in the Turkey Creek watershed ......................................................................... 109

32. Summary statistics of daily values for water-balance terms from long-term simulations 

for (A) the entire Turkey Creek watershed and for areas of (B) metamorphic, (C) intrusive, 

and (D) fault-zone rocks and (E) Pikes Peak Granite ............................................................................................. 113

APPENDIX TABLES

A1. Frequency distribution for milliequivalent balances............................................................................................... 135

A2. List of detections in quality-control samples .......................................................................................................... 136

A3. Statistics for relative percent differences in duplicate samples............................................................................... 137

A4. Selected site characteristics for water levels measured in fall 2001 ....................................................................... 138
CONTENTS VII

CONVERSION FACTORS, VERTICAL DATUM, AND ABBREVIATIONS

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 National Geodetic Vertical Datum of 1929. Horizontal is referenced to the North 

American Datum of 1927.

Elevation, as used in this report, refers to distance above or below NGVD29. NGVD29 can be converted to the North American Vertical 

Datum of 1988 by using the the National Geodetic Survey Conversion Utility available at URL http://www.ngs.noaa.gov/TOOLS/

Vertcon/vertcon.html

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).

Additional Abbreviations

mL milliliter

m2/m3 square meter per cubic meter 

g m–2 s

–1 gram per square meter per second

Wm–2 watt per square meter

kPa kilopascal

J joule

min minute

Multiply By To obtain

Length

inch 2.54 centimeter (cm)

inch 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 4,047 square meter (m2)

acre 0.004047 square kilometer (km2)

square mile (mi2) 2.590 square kilometer (km2)

square mile (mi2) 640 acre

Volume

liter (L) 0.2642 gallon

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

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

Flow

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

cubic foot per second per square mile [(ft3/s)/mi2] 0.01093 cubic meter per second per square kilometer [(m3/s)/km2]

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

Power

watt 1 joules per second
GLOSSARY IX

GLOSSARY OF SELECTED TERMS

The following terms are defined as they are used in 

this report.

Aperture.—The width of individual fracture openings in 

rock. Aperture is measured across the fracture, perpendicular to the fracture length.

Base flow.—Streamflow that emanates from ground water 

contained in a conceptual base-flow reservoir that 

exists in the subsurface. It is base flow that typically 

sustains streamflow during rainless periods.

Brittle structures.—Fractures, joints, and faults in rocks that 

are the result of brittle rather than ductile deformation.

Contemporary.—This term is used in this report to indicate 

data that were collected as part of this study, or to 

indicate methods that were applied to data that were 

collected for this study.

Evapotranspiration.—The process of moisture moving 

from the surface and near-surface areas of the Earth to 

the atmosphere; it is the sum of evaporation from wet 

surfaces (leaves, wet soils and rock, surface-water 

bodies, for example), sublimation from snow or ice, 

and transpiration, which is water evaporated from plant 

stomates.

Fracture set.—A group of fractures that have a set of 

properties such as orientation or length, or both, that 

are similar.

Fracture network.—A group of fracture sets that comprise 

all of the fractures in a volume of rock.

Fracture porosity.—Porosity resulting from open fractures, 

faults, or cracks.

Ground water.—As used in this report, water in the subsurface under water-table conditions. Some unknown 

amount of ground water is not asscoaited with local 

streamflow. As used in this report, ground water represents the contents of interflow and base-flow reservoirs 

and additional unaccounted for ground water that is not 

associated with local streamflow.

GSNK.—Ground water that percolates to a conceptual area 

of the watershed that is not available to support local 

streamflow.

Hydrologic response unit (HRU).—A land surface with 

similar slope and aspect properties defined for 

modeling surface and near-surface hydrologic 

processes.

Interflow.—Streamflow that emanates from ground water in 

direct response to precipitation or snowmelt, or both, 

that is contained in a conceptual interflow reservoir in 

the subsurface. Interflow may consist of streamflow 

contributions from subsurface areas that are saturated 

or perched, or some combination of both. 

Interflow and base-flow reservoirs.—Conceptual subsurface portions of the watershed used for accounting 

purposes in runoff modeling.

Overland flow.—That part of precipitation that passes over 

the surface of the land and into the nearest surfacewater body without first passing beneath the surface. 

Generally in direct response to precipitation.

Potential porosity.—An estimate of porosity made on the 

basis of mathematical characterizations of outcrop 

fracture measurements extrapolated to rock groups. 

Recharge.—As used in this report, water added to the 

subsurface below the soil zone; it is the residual of 

precipitation, evapotranspiration, and overland flow. 

Recharge supports interflow, base flow, and underflow.

Rock group.—An assemblage of mappable rock types 

aggregated into a group on the basis of similarities.

Transmissivity.—Rate of movement of a volume of fluid 

through a medium. Units of measurement are L2/T, 

where L is length and T is time.

Underflow.—Ground water that leaves the watershed by 

means other than streamflow or evapotranspiration.
Abstract 1

Hydrologic Conditions and Assessment of 

Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

By Clifford R. Bossong, Jonathan Saul Caine, David I. Stannard, Jennifer L. Flynn, 

Michael R. Stevens, and Janet S. Heiny-Dash

Abstract

The 47.2-square-mile Turkey Creek watershed, in Jefferson County southwest of Denver, 

Colorado, is relatively steep with about 4,000 feet 

of relief and is in an area of fractured crystalline 

rocks of Precambrian age. Water needs for about 

4,900 households in the watershed are served by 

domestic wells and individual sewage-disposal 

systems. Hydrologic conditions are described 

on the basis of contemporary hydrologic and 

geologic data collected in the watershed from 

early spring 1998 through September 2001. 

The water resources are assessed using discrete 

fracture-network modeling to estimate porosity 

and a physically based, distributed-parameter 

watershed runoff model to develop estimates 

of water-balance terms.

A variety of climatologic and hydrologic 

data were collected. Direct measurements of 

evapotranspiration indicate that a large amount 

(3 calendar-year mean of 82.9 percent) of precipitation is returned to the atmosphere. Surfacewater records from January 1, 1999, through 

September 30, 2001, indicate that about 9 percent 

of precipitation leaves the watershed as streamflow in a seasonal pattern, with highest streamflows generally occurring in spring related to 

snowmelt and precipitation. Although conditions 

vary considerably within the watershed, overall 

watershed streamflow, based on several records 

collected during the 1940’s, 1950’s, 1980’s, and 

1990’s near the downstream part of watershed, 

can be as high as about 200 cubic feet per 

second on a daily basis during spring. Streamflow 

typically recedes to about 1 cubic foot per second 

or less during rainless periods and is rarely zero. 

Ground-water level data indicate a seasonal 

pattern similar to that of surface water in which 

water levels are highest, rising tens of feet in some 

locations, in the spring and then receding during 

rainless periods at relatively constant rates until 

recharged. Synoptic measurements of water levels 

in 131 mostly domestic wells in fall of 2001 indicate a water-table surface that conforms to topography. Analyses of reported well-construction 

records indicate a median reported well yield 

of 4 gallons per minute and a spatial distribution 

for reported well yield that has relatively uniform 

conditions of small-scale variability. Results from 

quarterly samples collected in water year 1999 at 

about 112 wells and 22 streams indicate relatively 

concentrated calcium-bicarbonate to calciumchloride type water that has a higher concentration of chloride than would be expected on the 

basis of chloride content in precipitation and 

evapotranspiration rates. Comparison of the 

1999 data to similar data collected in the 1970’s 

indicates that concentrations for many constituents appear to have increased. Reconnaissance 

sampling in the fall of 2000 indicates that most 

ground water in the watershed was recharged 

recently, although some ground water was 

recharged more than 50 years ago. Additional 

reconnaissance sampling in the spring and fall 

of 2001 identified some compounds indicative 

of human wastewater in ground water and 

surface water.
2 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

Outcrop fracture measurements were 

used to estimate potential porosities in three rock 

groups (metamorphic, intrusive, and fault zone) 

that have distinct fracture characteristics. The 

characterization, assuming a uniform aperture 

size of 100 microns, indicates very low potential 

fracture porosities, on the order of hundredths 

of a percent for metamorphic and intrusive rocks 

and up to about 2 percent for fault-zone rocks. 

A fourth rock group, Pikes Peak Granite, was 

defined on the basis of weathering characteristics. 

Short-term continuous and synoptic measurements of streamflow were used to describe baseflow characteristics in areas of the watershed 

underlain by each of the four rock groups and 

are the basis for characterization of base flow in a 

physically based, distributed-parameter watershed 

model. 

The watershed model, the PrecipitationRunoff Modeling System (PRMS), was used to 

characterize hydrologic conditions on the basis 

of precipitation and air temperature in 112 hydrologic response units for which physical characteristics were derived from mostly digital data. The 

watershed model also was used to characterize 

hydrologic conditions in subsurface portions of 

the watershed that are associated with streamflow. 

The model was conditioned, using a relatively 

small set of parameters, to match measurements 

of watershed and intrawatershed streamflow and 

point measurements of evapotranspiration, air 

temperature, and soil moisture. Results from the 

watershed model provide simulated estimates for 

water-balance terms in a contemporary simulation 

(January 1, 1999, through September 30, 2001) 

using precipitation and adjusted temperature 

data from within the watershed, and in a longterm simulation (October 1, 1948, through 

September 30, 1999) using precipitation and 

temperature data from near the watershed. The 

results of both simulations indicate that, on a 

watershed scale, base-flow reservoirs consistently 

contain about enough water to cover the watershed with 0.1 to 0.2 inch of water. The long-term 

simulations indicate that during a year with about 

14 inches of precipitation, the watershed baseflow reservoir may have about a –0.06 inch 

change in contents during periods with relatively 

small amounts of recharge. The results from 

watershed simulations also indicate that contents 

of base-flow reservoirs vary within the watershed; 

base-flow reservoirs contain little or no recoverable water for significant portions of many years 

in about 90 percent of the watershed. In areas 

where base-flow reservoirs contain no water, the 

only source of water for wells is water that has 

percolated to relatively deep parts of the system 

that are not associated with local streamflow; 

water withdrawn under these conditions will need 

to be replaced before base flow can resume. Estimates of the amount of water withdrawn by wells 

in 2001 in the Turkey Creek watershed are equal 

to a watershed depth of about 0.43 to 0.65 inch 

(about 0.0012 to 0.0018 inch per day).

INTRODUCTION

Water quality, water quantity, and population 

growth in the foothill portions of Jefferson County 

are of concern to the Jefferson County Board of 

County Commissioners and the Planning and Zoning 

Department. The Planning and Zoning Department 

desires to meet the needs of current residents for 

adequate supplies of good quality water and to prepare 

for the projected growth and demands on the water 

resource from future development. The Turkey Creek 

watershed is representative of the foothills portions of 

Jefferson County. Contemporary (2001) population in 

the Turkey Creek watershed is estimated at 11,064 

residents with projected population growth, using a 

2-percent per year rate, at 13,186 residents in 2010, 

and 15,313 residents in 2020 (Jefferson County 

Planning and Zoning Department, written commun., 

2001). 

Water supply in the foothills portions of 

Jefferson County is typically derived from domestic 

wells developed in the fractured crystalline rocks. 

There are many anecdotal reports of wells “going 

dry” or requiring modifications to maintain production, and the prospect of continued development raises 

some questions regarding water supply. In addition, 

domestic water is treated in individual sewagedisposal systems (ISDS) and returned to the local 

system as ISDS effluent from leach fields, and this has 

raised some concerns regarding the quality of water.
INTRODUCTION 3

An understanding of hydrologic processes, especially those related to ground water, is a fundamental 

step in assessing contemporary (2001) quality and 

quantity of ground water. Together, the U.S. Geological 

Survey (USGS) and Jefferson County undertook a 

cooperative study of hydrologic conditions and assessment of water resources in Turkey Creek watershed 

beginning in 1998.

Purpose and Scope

 The purpose of this report is to describe 

contemporary (2001) hydrologic conditions and to 

provide a hydrologic assessment of water resources 

in the Turkey Creek watershed. Hydrologic conditions 

are described on the basis of evapotranspiration, 

surface water, ground water, and water quality. In 

addition, a description of rock-fracture characteristics 

based on outcrop-scale measurements is included. The 

watershed assessment includes estimates of fracture 

porosity and a characterization of water-balance terms 

using a watershed precipitation-runoff model.

The scope of the study includes historical 

climatologic data collected by study-area residents, 

contemporary data collected during the study from 

1998 to 2001, and historical data from agencies such 

as the Colorado Climate Center, State Engineers 

Office (SEO), and the USGS. Various methods, 

including geologic mapping and precipitation-runoff 

modeling, were used to assess water resources in the 

study area.

Location and Setting

The study area is the 47.2-mi2 Turkey Creek 

watershed (fig. 1), in Jefferson County southwest 

of Denver, Colo., in the foothills of the Front Range 

Section of the Southern Rocky Mountains physiographic province (Fenneman, 1931). Included in the 

study area are many developed areas such as Conifer, 

Aspen Park, and Indian Hills. It is estimated that there 

are about 4,900 households in the study area, or, 

on average, about one household for every 6 acres 

(Jefferson County Planning and Zoning Department, 

written commun., 2001). About 62 percent of households in the watershed are single-family detached 

homes.

The watershed topography is mostly steep 

and often rocky with elevations ranging from about 

10,500 ft in the southwestern part of the watershed 

to about 6,000 ft at the mouth of Turkey Creek canyon 

where the stream exits the foothills. Numerous 

bedrock outcrops in the study area border relatively 

gentle, open parks, such as Aspen Park, and stream 

valleys, such as North and South Turkey Creeks. 

Bedrock consists of fractured igneous and metamorphic crystalline rocks of Precambrian age that are 

extensively deformed. A more detailed geologic 

description is presented in the “Geologic Framework” 

section.

Previous Investigations

Several previous studies have been done on the 

chemical quality and physical quantity of the water 

resource in the Turkey Creek watershed. Snow (1968, 

1972) and Waltz (1972) discussed the importance of 

fractured-bedrock aquifer characteristics in influencing the ground-water flow regime. Hofstra and 

Hall (1975a, 1975b) collected, compiled, and analyzed 

water-quality data for Phase I of an investigation to 

determine the effects of development on the water 

availability, water quality, and controlling factors 

in several mountain communities. Phase II of that 

investigation (Hall and Johnson, 1979) indicated 

that, although water quality was degrading, it was still 

acceptable for drinking. Seasonal fluctuations in water 

levels were observed (Hall and Johnson, 1979), and 

over a 3-year period there was an overall decline in 

water levels that may reflect short-term climatological 

factors or increased withdrawal from ground water. 

Recent work by Bruce and McMahon (1997) and 

Stevens and others (1997) provides water-quality 

data from the Turkey Creek watershed and other 

Front Range mountainous settings that can be 

compared to the results of this study.

Acknowledgments

The authors thank various local, State, and 

Federal agencies for their cooperation in providing 

information and data that were used in preparing this 

report, specifically the Colorado Department of Public 

Health and Environment; Colorado Division of Water 

Resources; Jefferson County Board of Commissioners; 

Jefferson County Planning and Zoning Department;
4 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

 

 

 

 

 

 

Park County Jefferson County

Conifer

Aspen Park

Watershed

boundary

0

0 0.5 1 1.5 2 2.5 3 KILOMETERS

0.5 1 1.5 2 2.5 3 MILES

C O L O R A D O

39°37'48"

39°36'

39°34'12"

39°32'24"

39°30'36"

105°23'24" 105°21'36" 105°19'48" 105°18'0" 105°16'12" 105°14'24" 105°12'36" 105°10'48"

A

B

CD

E

FG

C Site with specific-conductance

 measurement

EXPLANATION

Elk Creek

Cheesman

Bailey

PARK COUNTY

JEFFERSON

COUNTY

Phillipsburg

Homewood Park

Oehlmann Park

Sky Village

Meyer

Ranch Park

Marshdale

Indian

Hills

Wild Rose

Grange

Fenders

Tiny

Town

Lone Pine

Estates

South Turkey Creek

North

Turkey Creek

Base modified from U.S. Geological Survey

digital data for 1:24,000 maps

EXPLANATION

Roads

Streams

Watershed

Figure 1. Location of Turkey Creek watershed in Jefferson County, Colorado; identifier and locations for sites with specificconductance measurement; and location of Bailey, Cheesman, and Elk Creek climatologic monitoring stations.
GEOLOGIC FRAMEWORK 5

members of the Mountain Ground-Water Resource 

Study Steering Committee; and the U.S. Environmental 

Protection Agency, Region VIII. Thanks also to 

Stephanie R.A. Tomusiak, Department of Geological 

Sciences, University of Colorado, Boulder, for her 

contributions to the fracture-data collection, analyses, 

and modeling efforts. Field assistance for outcrop 

measurements of fracture characteristics was provided 

by Ari Menitove, Jessica Beck, Sonya Cadle, Ben 

Glass, David Gardner, and Jared Lewis. Special appreciation also is expressed to Dick Burrows and Dorothy 

Hatch, dedicated volunteers that made monthly waterlevel measurements throughout the watershed during 

the study, as well as individuals who collected precipitation data, and homeowners who allowed various activities on their property such as water-level measurements, 

precipitation measurements, access to outcrops for fracture measurements, access to stream-sampling sites, and 

ground-water sample collection.

GEOLOGIC FRAMEWORK

A compilation of existing USGS geologic quadrangle maps for the Turkey Creek watershed shows a 

complex arrangement of Precambrian-age crystalline 

metamorphic and intrusive rock types (fig. 2 and 

table 1; Char, 2000, modified from Sheridan and others, 

1972; Bryant and others, 1973; Scott, 1972; Bryant, 

1974). Figure 3 is a simplified version of the geology 

shown in figure 2 and the rock types in table 1, 

produced by combining individual rock types into 

rock groups. Rock groups were identified on the 

basis of lithologic similarity, structural history, and 

geologic setting. For each rock group it is assumed 

that (1) ground-water flow and storage predominantly 

occurs in fracture networks, and that (2) because each 

rock group is composed of similar rock types that have a 

similar geological history and response to brittle deformation, they will exhibit similar hydrogeological properties (for example, porosity). Three important rock 

groups that contain subgroups were used to aid in establishing a geologic and hydrologic framework model. 

The rock groups are (1) metamorphosed and foliated 

gneisses and schists, referred to as the “metamorphic 

rock group;” (2) large-scale intrusive quartz monzonites 

found in plutons and consisting mostly of the Silver 

Plume Quartz Monzonite, referred to as the “intrusive 

rock group;” and (3) major fault zones that cut all rock 

types, referred to as the “fault-zone rock group” (fig. 3). 

Further division of the metamorphic and intrusive rock 

groups results in three subgroups: (1a) amphibolites, 

calc-silicates, and quartzites, (2a) the Pikes Peak 

Granite, and (2b) granitic pegmatite dikes that crosscut the metamorphic and intrusive rock groups (table 1). 

The metamorphic, intrusive, and fault-zone rock groups 

plus subgroup 2a (the Pikes Peak Granite) are collectively referred to as the “four rock groups” in this report; 

group 1a is included in the metamorphic rocks and 

group 2b is included in the intrusive rocks. 

The major rock types include approximately 

1.7-billion-year-old gneisses and schists (metamorphic 

rocks). These rocks are typically well layered due to 

original compositional variations and metamorphic 

processes (Bryant, 1974; Bryant and others, 1975). 

They are part of the Turkey Creek Formation and are 

similar to the rocks in the Idaho Springs Formation 

(Lickus and LeRoy, 1968). The metamorphic rocks are 

intruded or cut by the approximately 1.4-billion-yearold Silver Plume Quartz Monzonite, which is a rock 

type similar to granite (intrusive rocks) (Bryant, 1974). 

These intrusive rocks are heterogeneously distributed in 

the watershed. The intrusive bodies range in size from 

small, dikelike features 50–100 ft long to large and 

irregular plutonlike bodies with large apophyses miles 

long. Pegmatitic dikes also cut the intrusive rocks. The 

pegmatites are highly irregular in shape and size and are 

less than a few feet to several miles long.

The major geologic structures in the watershed 

include folds and fault zones. The layering in the 

metamorphic rocks is generally steeply to moderately 

tilted and generally strikes northwest to southeast. 

This tilting is associated with the proximity of the 

observed outcrops to the limbs of several regional 

scale folds (Bryant and others, 1973). Many localto outcrop-scale folds and highly contorted layering 

zones are present throughout the watershed. 

A variety of brittle fault structures or fault zones 

are present in the watershed (fig. 3), and the Appendix 

contains a detailed discussion of these features. Brittle 

fault zones are in the form of unusually wide fracture 

networks (tens of feet to greater than miles wide) 

where most of the zone is composed of open fractures 

with little offset on them and a few discrete fractures 

where most of the offset has occurred. Other brittle 

fault zones are relatively narrow (a few feet wide) fault 

breccia zones that have anastomosing and discrete 

fractures where motion has taken place and where 

fracture networks have been mineralized with quartz, 

calcite, and other associated minerals.
6 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

Amphibolite, quartzite, marble, and

 associated rocks

Artificial fill

Rutile-bearing sillimanite quartzite

Shonkinite

Biotite gneiss and associated rocks

Sillimanitic biotite gneiss containing

 garnet-bearing layers, and cordierite-

 feldspar-rich gneiss

Well-foliated, medium-grained biotite-

 quartz monzonitic or granitic gneiss

Felsic gneiss

Garnet-mica gneiss

Quaternary alluvium

Coarse-grained pegmatite

Fountain Formation (Permian- and

 Pennsylvanian-age sediments)

Feldspar-rich gneiss

Migmatitic quartzo-feldspathic gneiss

Gneissic quartz monzonite

Interlayered hornblende and calc-

 silicate gneiss and amphibolite

Migmatite

Mafic granodiorite and quartz mon-

 zonite

Pikes Peak Granite

Silver Plume Quartz Monzonite

Fault zone

Fine-grained porphyritic phase of

 Pikes Peak Granite

Parmalee Gulch

S. Turkey Creek

N. Turkey Cr.

Giant Gulch

Turkey Creek Iowa Gulch

Lone Pine

Estates

Wild Rose Grange

Marshdale

Tiny Town

Indian

Hills

Fenders

Phillipsburg

Homewood Park

Oehlmann

Park

Conifer

8

To Morrison

C470

Shadow Mountain Road

N. Turkey Creek Rd

Parma lee Gulch

Road

285

285

Marshdale

39°32'24"

39°30'36"

39°34'12"

39°36'

39°37'48"

105°23'24" 105 105°21'36" °19'48" 105°18' 105°16'12" 105°14'24" 105°12'36" 105°10'48"

Fault

Subbasins

Drainage

Roads

Population centers

0

0 0.5 1 1.5 2 2.5 3 KILOMETERS

0.5 1 1.5 2 2.5 3 MILES

Watershed 

boundary

EXPLANATION

Base modified from U.S. Geological Survey

digital data for 1:24,000 maps

Figure 2. Compilation of parts of the existing Evergreen, Indian Hills, Morrison, Conifer, and Meridian Hills U.S. Geological 

Survey Geologic Quadrangle Maps.
GEOLOGIC FRAMEWORK 7

285 South n=114

285 North n=95

Harrington n=193

LeGault Peak n=119

C73 Fault Zone

n=139

Green n=180

Lambert n=94

Nobel n=150

US40 Fault Zone n=131

Note: The circular diagrams are equalarea plots that indicate strike, dip, and 

number of fractures mapped (m). A 

more detailed explanation of the 

diagrams is given in the appendix. 

39° 30' 36"

105° 19' 48"

EXPLANATION

Metamorphosed and foliated

 gneisses and schists

Amphibolites, calc-silicates,

 and quartzites

Intrusive quartz monzonites

Granitic pegmatite dikes

Pikes Peak Granite

Fault zone

Faults

Fracture data-collection site

0

0 0.5 1 1.5 2 2.5 3 KILOMETERS

0.5 1 1.5 2 2.5 3 MILES

Figure 3. Simplified geologic map, locations of outcrops where fracture characteristics were measured or observed, 

and fracture-orientation data for measurements at each location.
8 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

The Colorado Rocky Mountain Front Range has 

a long and complex geologic history and associated 

brittle deformation. There are at least three generations 

of brittle deformation associated with the Precambrian 

rock in the watershed: (1) early Paleozoic-age burial 

and late Paleozoic-age Ancestral Rocky Mountain 

uplift, (2) mid- to late Mesozoic-age burial and late 

Mesozoic-age to early Cenozoic-age Laramide uplift, 

and (3) late Cenozoic-age volcanism, uplift, and 

possible extension (for example, Sonnenberg and 

Bolyard, 1997). This protracted geologic history 

and the response of the various rock types to deformation led to the complex joint (fractures with no 

shearing motion along them) and fault patterns that 

are observed today. The Turkey Creek watershed 

represents a relatively undeformed portion of the Front 

Range relative to areas to the north in the Colorado 

Mineral Belt (Tweto and Sims, 1963).

Quaternary-age alluvium in the Turkey Creek 

watershed is sparse and is present primarily along 

stream channels and in open areas locally known as 

parks (fig. 2). The dominant soil types (stony loams to 

rock outcrops) are generally thin (about 2 to 3 ft thick), 

have generally low water availability, have moderate 

to high permeability, and are on moderate to steep 

slopes (U.S. Department of Agriculture, 1980). In 

addition, locally derived, very near-surface, bedrock 

weathering may be hydraulically significant. Thicker 

zones of weathered bedrock exist predominantly 

where there are coarse-grained intrusive rocks, 

Table 1. Individual rock types assigned to rock groups in the Turkey Creek watershed

[Individual rock types taken from the explanation in figure 2 are assigned to rock groups based on lithologic similarity, structural history, and geologic 

setting. The groups include (1) metamorphosed and foliated gneisses and schists; (1a) amphibolites, calc-silicates, and quartzites; (2) large-scale intrusive 

quartz monzonites found in plutons and consisting mostly of the Silver Plume Quartz Monzonite; (2a) Pikes Peak Granite and other granites; (2b) granitic 

pegmatites; and (3) major fault zones that cut all rock types. NP indicates rock types not present in the study area and Quaternary-age deposits have not been 

included. Y indicates Precambrian-age rocks that formed between 1.04 and 1.44 billion years ago, and X indicates rocks between 1.71 and 1.75 billion years 

old for this area. All other units are undated Precambrian-age rocks unless otherwise stated. The following is from Char, 2000, modified from Sheridan and 

others, 1972; Bryant and others,1973; Scott, 1972; and Bryant, 1974]

Rock type name Rock group

assignment

Shonkinite NP

Fountain Formation (Permian and Pennsylvanian-age sediments) NP

Pikes Peak Granite 2a

Silver Plume Quartz Monzonite 2

Fine-grained porphyritic phase of Pikes Peak Granite 2a

Granitic rock 2a

Coarse-grained pegmatite 2b

Mafic granodiorite and quartz diorite 2

Gneissic granodiorite and quartz monzonite 1

Gneissic quartz monzonite 1

Migmatitic quartzo-feldspathic gneiss 1

Migmatite 1

Amphibolite, quartzite, marble, and associated rocks 1a

Amphibolite 1a

Biotite gneiss and associated rocks 1

Sillimanitic biotite gneiss containing garnet-bearing layers, and cordierite-feldspar-rich gneiss 1

Interlayered hornblende and calc-silicate gneiss and amphibolite 1a

Feldspar-rich gneiss 1

Garnet-mica gneiss 1

Well-foliated, medium-grained biotite-quartz monzonitic or granitic gneiss 1

Felsic gneiss 1

Rutile-bearing sillimanite quartzite 1a

Fault zone 3
DATA COLLECTION AND METHODS 9

especially overlying the Pikes Peak Granite. Significant areas of weathered bedrock also occur where 

there are metamorphic rocks that are dominantly 

composed of hornblende and a variety of amphiboles. 

Field observations and anecdotal information from 

water-well drillers indicate that weathered bedrock is 

rare to absent except in the southwestern part of the 

watershed where the Pikes Peak Granite crops out 

(fig. 2). Weathering probably extends to depths of 

about 10 ft or less and is nonuniformly distributed 

where the Pikes Peak Granite crops out and in particular where it has been glaciated. 

Surficial deposits of alluvium and soils are thin 

and not present everywhere in the Turkey Creek watershed; although the surficial deposits contain water, 

most wells in the watershed are completed in the crystalline bedrock and most water used for domestic 

supply in the watershed is withdrawn from the crystalline bedrock. The crystalline bedrock has very low 

primary, or intergranular, porosity; rather, open space 

that may contain water in the crystalline rocks consists 

mostly of fractures and fracture networks. The fractured bedrock aquifer system in the Turkey Creek 

watershed is the fractures and fracture networks in 

the crystalline rocks.

DATA COLLECTION AND METHODS

Data used as part of this study are described in 

this section. Data collected in previous USGS studies 

and data compiled or collected by other agencies are 

referred to as “historical data,” and data collected as 

part of this study, beginning in 1998 and continuing 

through September 2001, are referred to as “contemporary data.” Some of the methods used in analyzing 

these data also are described in this section. Detailed 

descriptions of specialized methods used in developing estimates of fracture-network porosity, measurements of evapotranspiration, and characterization of 

spatial characteristics for some well-construction 

records are described in the Appendix. The preferred 

system of units for reporting in this report is the 

English inch-pound system; however, some data, such 

as those related to energy measures and rock fractures, 

are described in metric units as this is a standard and 

accepted practice.

Historical Data

Much data for the Turkey Creek watershed 

collected as part of previous studies or maintained by 

agencies other than the USGS were used in this study. 

These data provide some descriptions of historical 

climatologic, streamflow, ground-water level, and 

water-quality conditions in or around the watershed. 

The data also include well-construction records available from the Colorado State Engineer’s Office (SEO) 

and miscellaneous data available from the Jefferson 

County Planning and Zoning Department including 

summaries of U.S. Census Bureau information, 

projections of population growth, locations of occupied households, some historical land-use classifications, and digital orthophoto imagery. 

The Colorado Climate Center, in cooperation with the National Weather Service, maintains 

climatologic records for many locations in Colorado 

(Colorado Climate Center, 2002). Records for precipitation and daily air temperature extremes from 

three stations—Bailey (station 50454), Cheesman 

(station 51528), and Elk Creek (station 52633)—

were used as part of this study (fig. 1). In addition, 

a detailed precipitation record covering more than 

40 years (1956–99) was available from John and 

Marguerite Schoonhoven of Flying J Ranch (RG12 

in table 2). Several other intermittent and short-term 

records of snowfall and temperature were available 

from various sources.

Historical records include those collected 

previous to this study and consist of data from two 

stream gages on Turkey Creek in the vicinity of the 

present gage (06710992, fig. 4). A summary for timeseries data indicating periods of record for stream 

gages and other data is presented in table 2. Some 

historical records, from the late 1980’s, of surfacewater discharge, or streamflow, in the Turkey Creek 

watershed are available from the Automatic Data 

Processing System (ADAPS) part of the National 

Water Inventory System (NWIS) (Bartholoma, 1997). 

NWIS is a computer system established by the USGS 

to manage and provide some analytical capabilities 

for a wide variety of hydrologic information; ADAPS 

addresses continuous records of many hydrologic data, 

including surface-water records. Additional historical 

records of streamflow from the 1940’s and 1950’s are 

not included in the NWIS but have been compiled in 

publications (U.S. Geological Survey, 1942–53).
10 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

Table 2. List of sites with time-series records

[Note: primary identifier, U.S. Geological Survey (USGS) station identification number or National Weather Service (NWS) station number; 

 identifier type refers to source for identifier (1 - USGS, 2 - Colorado Climate Center, 3 - State Engineers Office); Local identifier, 

 local identifier used by this study; Location, latitude and longitude in nad27; Elevation, feet above NGVD29; Type, defines type of data 

 collected at site (1 - total daily precipitation [a - tipping bucket, b - weighing bucket], 2 - daily minimum and maximum air temperature, 

 3 - mean daily discharge, 4 - soil moisture, 5 - solar radiation, 6 - evapotranspiration, 7 - daily mean diversion, 8 - intermittent or 

 monthly depth-to-water measurements, 9 - mean daily depth to water ); --, not applicable]

------------------------------------------------------------------------------------------------------------------------------------------

 Identifier

----------------------------

 primary type local Location Elevation Type Period of record Site name

------------------------------------------------------------------------------------------------------------------------------------------

 DISCHARGE AND DIVERSIONS

06710992 1 -- 393703 1051324 6420 3 April 13, 2001 - continuing Turkey Creek near Indian Hills 

06710995 1 SWA01 393713 1051141 6040 3 April 1, 1998 - April 13, 2001 Turkey Creek at mouth of

 Canyon near Morrison

06711040 1 -- 393827 1050934 5635 3 June 19, 1942 - September 30, 1953 Turkey Creek above Bear Creek

 Lake near Morrison

06711000 1 -- 393809 1051003 -- April 25, 1986 - September 30, 1989 Turkey Creek near Morrison

393203105221600 1 STR-1 393203 1052216 9100 3 April 10, 2001 - August 1, 2001 North Turkey Creek upper tributary

 above Aspen Park

393210105205500 1 STR-2 393210 1052055 8435 3 April 10, 2001 - August 1, 2001 North Turkey Creek above Warhawk 

 near Aspen Park

393141105200500 1 STR-3 393141 1052005 8350 3 April 17, 2001 - August 1, 2001 North Turkey Creek tributary

 above Aspen Park

393443105165800 1 STR-4 393443 1051658 7615 3 April 13, 2001 - August 1, 2001 North Turkey Creek tributary near

 Gartner Drive near Aspen Park

 -- 3 head 12 393714 1051155 6115 7 -- - -- Headgate Independent Highline # 12

 -- 3 head 27 393714 1051141 6015 7 -- - -- Headgate Bergen # 27

 CLIMATOLOGIC 

393213105142100 1 RG1 393213 1051421 7460 1a December 1, 1998 - September 30, 2001 RG1

393145105195900 1 RG2 393145 1051959 8250 1a no record RG2 

393204105141700 1 RG3 393204 1051417 7900 1a December 1, 1998 - September 30, 2001 RG3

393404105182701 1 RG4 393404 1051822 7820 1a December 1, 1998 - September 30, 2001 RG4

393143105135600 1 RG5 393143 1051356 8480 1a December 1, 1998 - September 30, 2001 RG5

393459105170300 1 RG6 393459 1051703 7560 1a December 1, 1998 - September 30, 2001 RG6 

393552105144201 1 RG7 393552 1051442 7480 1a December 1, 1998 - September 30, 2001 RG7

393700105114500 1 RG8 393700 1051145 6040 1b,2 August 28, 1998 - September 30, 2001 RG8/AT1

393423105131000 1 RG9 393423 1051310 7160 1b September 23, 1998 - September 30, 2001 RG9

393249105181900 1 RG10 393248 1051819 8240 1b February 2, 1999 - September 30, 2001 RG10

393340105201500 1 RG11 393340 1052015 8180 1b November 25, 1998 - November 23, 20011 RG11

 -- 1 RG12 393237 1051912 7980 1,2 January 1, 1956 - December 30, 1999 RG12

50454 1 RG13 392421 1052822 7730 11,2 August 1, 1948 - December 31, 1997 Bailey

51520 2 RG14 391313 1051640 6890 11,2 August 1, 1948 - June 30, 2000 Cheesman

52633 2 RG15 392953 1052000 8440 11,2 August 1, 1948 - September 30, 1951 Elk Creek

 -- 2 RG16 393227 1051925 8180 1a,2, February 3, 1999 - December 31, 2001 RG16/ ET Forest site/ ET Tower

 4,5,6

 -- 2 RG17 393429 1051638 7770 1a,2, June 2, 2000 - December 31, 2001 RG17/ ET Meadow site

 4,5,6

 -- 2 RG18 393429 1051638 7770 1b December 6, 2000 - September 30, 2001 RG18/ ET Forest site

 -- 2 AT2 393104 1052109 9760 2 April 1, 2001 - September 30, 2001 Elk Creek Fire 

 Station at Conifer Mountain 

 -- 2 AT3 393304 1051621 8200 2 March 23, 2001 - September 30, 2001 North Meyer Ranch Park

 -- 2 AT4 393223 1051624 8200 2 March 23, 2001 - September 30, 2001 South Meyer Ranch Park

 DEPTH TO WATER

393821105161001 1 MH1 393820 1051612 7310 8 September 5, 1973 - February 14, 1983 MH1

 August 25, 1998 - continuing

 9 May 23, 2001 - September 30, 2001

393604105132100 1 MH2 393604 1051321 6900 8 November 4, 1998 - continuing MH2

393513105181300 1 MH3 393513 1051813 7751 8 July 9, 1998 - continuing MH3

393459105165701 1 MH4 393459 1051657 7672 8 December 3, 1998 - continuing MH4

393350105184401 1 MH5 393350 1051844 7900 8 September 5, 1973 - February 14, 1983 MH5

 August 25, 1998 - continuing

 9 May 23, 2001 - September 30, 2001

393348105171400 1 MH6.1 393348 1051714 8375 8 December 3, 1998 - continuing MH6.1

393344105171400 1 MH6.2 393344 1051714 8352 8 December 3, 1998 - continuing MH6.2

393342105171500 1 MH6.3 393342 1051715 8340 8 December 3, 1998 - continuing MH6.3

39333210515 800 1 MH7 393332 1051508 8337 8 December 3, 1998 - continuing MH7

393301105150201 1 MH8 393301 1051532 8050 8 September 6, 1973 - February 14, 1983 MH8

 July 9, 1998 - continuing

 9 May 23, 2001 - September 30, 2001 

393121105110600 1 MH9 393121 1051106 6720 8 September 6, 1973 - February 14, 1983 MH9

 August 25, 1998 - September 30, 2001

392958105164601 1 MH10 392958 1051646 7950 8 September 6, 1973 - February 14, 1983 MH10

 August 25, 1998 - September 30, 2001

393112105182100 1 MH11 393112 1051821 8477 8 June 18, 1998 - continuing MH11

393143105195400 1 MH12 393143 1051954 8187 8 July 10, 1998 - continuing MH12

393717105145300 1 MH13 393717 1051453 7279 8 May 11, 1999 - continuing MH13
DATA COLLECTION AND METHODS 11

Two stream gages on Turkey Creek were operated by the USGS at various times previous to this 

study. Station 06711040, Turkey Creek above Bear 

Creek Lake near Morrison, about 1.5 mi downstream 

from the present gage (station 06710992) (fig. 4), 

has data available from April 25, 1986, through 

September 30, 1989. Station 06711000, Turkey Creek 

near Morrison, about 1 mi downstream from the 

present gage, has data available from June 19, 1942, 

through September 30, 1953. Diversions from Turkey 

Creek upstream from these stations complicate 

streamflow records. Although streamflow records 

at these stations have an acceptable level of accuracy, 

they are not representative of stream regulation that 

occurs upstream from the gages. Regulation activity 

typically consists of diversions. The water diverted 

from streams is not measured at the gages; consequently, the gage record is “low biased,” or consistently less than the sum of measured streamflow and 

the diversion, during times of diversion. Regulation 

also may include addition of water to streams. Records 

for diversions from the Independent Highline and 

Bergen ditches (fig. 4) are available from the SEO; 

other records from potential additional diversions or 

additions are not available. 

The SEO is responsible for issuing permits for 

well construction in Colorado. As part of the permitting process, many well-construction details are 

obtained by the SEO and retained in their files. Many 

of these data, such as legal description, drillers’ logs, 

------------------------------------------------------------------------------------------------------------------------------

Parmalee Gulch

S. Turkey Creek

N. Turkey Cr

Giant Gulch

Turkey Creek Iowa Gulch

Lone Pine

Estates

Wild Rose Grange

Marshdale

Tiny Town

Indian

Hills

Fenders

Phillipsburg

Homewood Park

Oehlmann

Park

Conifer

8

To Morrison

C470

Shadow Mountain Road

N. Turkey Creek Rd

Parma lee Gulch

Road

285

285

Marshdale







SWD01

D

Head

#12

A

B

E

D C

F

L M

H

P

G

STR-4

STR-3

STR-2

STR-1

STR-1

I

J

K

N

O

39°32'24"

39°30'36"

39°34'12"

39°36'

39°37'48"

105°23'24" 105 105°21'36" °19'48" 105°18' 105°16'12" 105°14'24" 105°12'36" 105°10'48"

EXPLANATION

Study area

Subbasins

Drainage

Roads

Subbasin code

Population centers

Evapotranspiration

 tower

Surface-water site

Irrigation ditch

Stream gage

0

0 0.5 1 1.5 2 2.5 3 KILOMETERS

0.5 1 1.5 2 2.5 3MILES

SWA01

SWB01

SWB02

SWC01

SWM01

SWN01

SWF01

SWL01

SWE01

SWD01 SWA02

SWA03

SWA04

SWA05

SWG01

SWH01

SWI01

SWJ01

SWP01

SWK02

SWK01

SWO01

Head #12

Head #27

Turkey Creek above

Bear Creek

Turkey Creek 

near Morrison

Base modified from U.S. Geological Survey

digital data for 1:24,000 maps

Figure 4. Locations of surface-water streamflow measurement and sampling sites, stream gages, and irrigation ditches.
12 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

and well-completion diagrams, are only available 

in paper format or scanned images of original paper 

copies. However, some data are available electronically as digital records. The SEO has about 3,300 

digital well records with construction details on file 

for the Turkey Creek watershed. About 1,100 of those 

wells, referred to in this report as “permitted wells,” 

have defined locations that are shown in figure 5. The 

digital data describe reported well yield, total depth, 

and depth to water. 

Water-quality data from previous studies were 

available for use in this study. Most of these data were 

collected in the 1970’s as part of the work by Hofstra 

and Hall (1975a) and Hall and others (1981). Bruce 

and McMahon (1997) also collected water-quality data 

from a number of wells in Front Range settings, a 

few of which are in the watershed. In addition, Bruce 

and McMahon (1997) and Stevens and others (1997) 

collected water-quality data from wells completed in 

fractured rocks in other Front Range areas that can be 

compared to data collected during this study. All of 

these data include analyses for many water-quality 

properties and constituents addressed by this study as 

well as other constituents that are useful to this study. 

The locations for samples collected during previous 

studies in the Turkey Creek watershed are shown in 

figure 6. Univariate statistics for water-quality properties and constituents including major ions and some 

nutrients collected in previous studies are listed in 

table 3.

Parmalee Gulch

S. Turkey Creek

N. Turkey Cr

Giant Gulch

Turkey Creek Iowa Gulch

Lone Pine

Estates

Wild Rose Grange

Marshdale

Tiny Town

Indian

Hills

Fenders

Phillipsburg

Homewood Park

Oehlmann

Park

Conifer

8

To Morrison

C470

Shadow Mountain Road

N. Turkey Creek Rd

Parma lee Gulch

Road

285

285

Marshdale







D A

B

E

D C

F

L M

H

P

G

I

J

K

N

O

39°32'24"

39°30'36"

39°34'12"

39°36'

39°37'48"

105°23'24" 105 105°21'36" °19'48" 105°18' 105°16'12" 105°14'24" 105°12'36" 105°10'48"

EXPLANATION

Study area

Subbasins

Drainage

Roads

Subbasin code

Population centers

Evapotranspiration 

 tower

Well

Well with yields

 greater than 15

 gallons per minute

0

0 0.5 1 1.5 2 2.5 3 KILOMETERS

0.5 1 1.5 2 2.5 3 MILES

Base modified from U.S. Geological Survey

digital data for 1:24,000 maps

Figure 5. Locations of permitted wells from the State Engineers Office.
DATA COLLECTION AND METHODS 13

Contemporary Data

Many types of data were collected as part of 

this study, beginning in 1998 and continuing through 

September 2001, to describe fracture characteristics, 

climate, evapotranspiration, streamflow, ground-water 

level, and ground- and surface-water quality in the 

vicinity of the Turkey Creek watershed. The general 

nature of these contemporary data is described in this 

section.

Fracture Characteristics

One goal of this study is to identify and quantify 

the major parameters that control the hydraulics of 

ground-water flow at the watershed scale and thus 

better determine how much ground water can be 

transmitted to and stored within the complex fractured 

bedrock aquifer system in the Turkey Creek watershed. Some major questions are: (1) how do fracture 

intensity and orientation control fracture-network 

porosity (indicator of potential storage), (2) how does 

fracture porosity vary within individual lithologies, 

and (3) because distinct fracture networks are associated with distinct geologic structures (for example, 

faults and folds), how do fracture-network parameters 

that translate into hydraulic heterogeneity vary among 

different types of structures and how might they vary 

between the same type of structure in different lithologies? One way of approaching these questions is 

to collect and analyze fracture data and construct

Parmalee Gulch

S. T urkey Creek

N. Turkey Cr

Giant Gulch

Turk ey Cre ek Iowa Gulch

Lone Pine

Estates

Wild Rose Grange

Marshdale

Tiny Town

Indian

Hills

Fenders

Phillipsburg

Homewood Park

Oehlmann

Park

Conifer

8

To Morrison

C470

Shadow Mountain Road

N. Turkey Cree k Rd

Parma lee Gulch

Road

285

285

Marshdale

M

M

M

D A

B

E

D C

F

L M

H

P

G

I

J

K

N

O

39 32'24"

39 30'36"

39 34'12"

39 36'

39 37'48"

105 23'24" 105 19'48" 105 18' 105 16'12" 105 14'24" 105 12'36" 105 10'48" 105 21'36"

EXPLANATION

Study area

Subbasins

Drainage

Roads

Subbasin code

Population centers

Evapotranspiration

 tower

Water-quality site

0

0 0.5 1 1.5 2 2.5 3 KILOMETERS

0.5 1 1.5 2 2.5 3 MILES

Base modified from U.S. Geological Survey

digital data for 1:24,000 maps

Figure 6. Spatial distribution of water-quality samples collected in previous studies in the Turkey Creek watershed.
14 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

computer models of fracture networks present in 

natural outcrop exposures. The following section 

discusses how this was accomplished in the Turkey 

Creek watershed.

Outcrop Selection

Color aerial photographs (at a scale of about 

1:12,000) were initially used to identify exposures of 

the dominant rock groups (described in the “Geologic 

Framework” section). Field inspection narrowed the 

range of suitable sites. Final outcrop selection also was 

based on how representative a given outcrop was of its 

rock group (that is, that the structures and lithologies 

were similar at the outcrop scale to what was observed 

for most outcrops in the watershed). Nine outcrop 

localities were studied in detail (fig. 3), and four others 

were studied for supplemental data and observation. 

The amount of data collected at each outcrop varied 

depending on outcrop size, quality of exposure, and 

physical accessibility. About 100 or more fractures 

were measured at each locality, and more than 

10,000 fracture attributes were measured in total. 

Outcrops at least 100 ft long and with at least two 

near-orthogonal faces were sought. By taking 

measurements on two near-orthogonal faces, fractures 

that were sub-parallel to one face were captured on the 

second face, which helps to minimize orientation bias 

from random sampling of outcrop faces (see Appendix 

for details).

Methods of Fracture Measurement

Fracture data were collected along representative 

scanlines in each outcrop. A scanline is a graduated 

tape, or other marker, stretched across an outcrop face: 

fracture properties are measured along the scanline 

from beginning to end. The properties measured for 

each fracture that intersects the scanline include the 

following: position (from which fracture spacing and 

intensity are derived, as described in the Appendix), 

orientation (the strike and dip), trace length (typically 

not the actual diameter of the fracture but only the 

portion of it that intersects the outcrop face), termination (how the fracture tips end), an estimate of aperture 

size, degree and type of mineralization, shape, and 

roughness; also any indicators of timing relationships 

(for example, crosscutting and offset of other fracture 

sets) were recorded (Caine, 2001).

Climatologic Data

Seven tipping-bucket rain gages were operated 

by the USGS throughout the watershed beginning in 

the fall of 1998 (RG1–RG7; fig. 7 and table 2), and 

four weighing-bucket rain gages also were operated 

(RG8–RG11; fig. 7 and table 2). In addition, RG16 

and RG17 were established at sites of evapotranspiration measurements; records from RG16 are 

actually a composite of results from both a tippingand a weighing-bucket rain gage, and records from 

RG17 are from a tipping bucket. The tipping- and

Table 3. Univariate statistics for water-quality properties and constituents collected in previous studies

[Note: Detection, results greater than method reporting limit (rpl); Censoreds, results less than method reporting limit;

 Q1, concentration at the 25th percentile; Q3, concentration at the 75th percentile; Min, minimum; Max, maximum; N, number 

 of samples; Percent < rpl, percentage of samples with concentration less than the reporting limit; na, not applicable; mg/L,

 milligrams per liter; μS, microsiemens per centimeter at 25o Celsius]

----------------------------------------------------------------------------------------------------------------------------

 Detections Censoreds 

 ---------------------------------------------------------- ------------------- Percent 

Variable Mean Median Q1 Q3 Min Max N Mean Median N < rpl

---------------------------------------------------------------------------------------------------------------------------- 

Specific conductance (μS/cm) 278.32 250.00 185.00 333.75 32.70 950.00 316 na na na na

Hardness, total (mg/L) 109.83 89.00 51.00 160.00 22.00 380.00 65 na na na na

Calcium, total [mg/L] 31.12 25.00 15.00 38.50 6.60 130.00 65 na na na na

Magnesium, total [mg/L] 7.85 6.20 3.55 10.10 1.00 24.00 65 na na na na

Sodium, total [mg/L] 19.50 11.00 6.80 13.50 2.90 120.00 65 na na na na

Potassium, total [mg/L] 2.03 1.50 1.00 2.20 0.20 25.00 284 na na na na

Alkalinity (mg/L) 111.75 89.00 46.94 145.50 13.00 425.00 62 na na na na

Sulfate (mg/L) 13.39 10.00 5.40 14.00 1.20 90.00 65 na na na na

Chloride (mg/L) 9.26 4.40 2.10 13.00 0.40 64.00 313 na na na na

Fluoride (mg/L) 0.66 0.50 0.30 0.70 0.10 2.90 65 na na na na

Nitrate/Nitrite, as N [mg/L) 2.03 0.50 0.11 1.90 0.01 36.00 299 na na na na

Phosphorus, total [mg/L] 0.04 0.03 0.02 0.04 0.01 1.30 209 na na na na

----------------------------------------------------------------------------------------------------------------------------
DATA COLLECTION AND METHODS 15

weighing-bucket gages were used to develop daily 

records of precipitation in the watershed. In addition 

to these daily records, intermittent records of snowfall 

and corresponding water equivalency were maintained 

at snow table sites by several homeowners (fig. 7). 

Additional climatic data were collected at evapotranspiration sites. Also, in the spring of 2001, four airtemperature sites were established in the watershed 

(AT1–4; table 2, one of the air temperature sites is 

collocated with RG8).

Evapotranspiration (ET) is the transport of water 

from the surface of the Earth to the atmosphere, and 

involves a change in phase, from liquid to gas. ET is 

the sum of evaporation from wet surfaces (leaves, wet 

soils and rock, and surface-water bodies, for example), 

sublimation from snow or ice, and transpiration, which 

is water evaporated from plant stomates. Stomates are 

microscopic holes connecting the surface of a leaf or 

needle to its interior cells. The primary purpose of 

stomates is to allow carbon dioxide (CO2) from the 

atmosphere to diffuse into the plant, where it is used 

for growth. Transpiration is fundamentally the same 

physical process as evaporation. Plants do not pump 

water out through stomates, they simply make liquid 

water available to the sub-stomatal cavities, where 

it is lost through the stomates in the process of 

obtaining CO2. Mean ET over land is about 62 percent 

of precipitation worldwide (Brutsaert, 1982). The ratio 

Parmalee Gulch

S. Turkey Creek

N. Turkey Cr

Giant Gulch

Turkey Creek Iowa Gulch

Lone Pine

Estates

Wild Rose Grange

Marshdale

Tiny Town

Indian

Hills

Fenders

Phillipsburg

Homewood Park

Oehlmann

Park

Conifer

8

To Morrison

C470

Shadow Mountain Road

N. Turkey Creek Rd

Parma lee Gulch

Road

285

285

Marshdale







D A

B

E

D C

F

L M

H

P

G

I

J

K

N

O

39°32'24"

39°30'36"

39°34'12"

39°36'

39°37'48"

105°23'24" 105 105°21'36" °19'48" 105°18' 105°16'12" 105°14'24" 105°12'36" 105°10'48"

EXPLANATION

Study area

Subbasins

Drainage

Roads

Subbasin code

Population centers

Evapotranspiration

 site

Rain gage site

Snow table site

0

0 0.5 1 1.5 2 2.5 3 KILOMETERS

0.5 1 1.5 2 2.5 3 MILES

ST1

ST2

ST4

ST5

ST6

ST9

ST7

ST3

ST8

RG1

RG2

RG3

RG4

RG5

RG6

RG7

RG8

RG9

RG10

RG11

RG11

ST4

RG12

Base modified from U.S. Geological Survey

digital data for 1:24,000 maps

Figure 7. Location of climatologic monitoring sites.
16 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

of ET to precipitation tends to be greater in arid 

climates and smaller in humid climates. The ratio of 

transpiration to evaporation (plus sublimation) generally increases as the amount of vegetation increases. 

In most regions, transpiration is much greater than 

evaporation on an annual basis.

The latent heat of vaporization of water (L) 

is the amount of energy needed to evaporate a unit 

amount of water. Because L is relatively large 

(2,450 joules g–1 at 70°F), ET is an important link 

between the water balance and the energy balance 

of a surface. In most climatic settings, a fairly large 

portion of the net energy received by the land surface 

as sunlight is transferred to the atmosphere through the 

evaporation of water. The energy balance of a vegetated surface, in terms of watts per square meter, can 

be written as:

(1)

where 

Rn is net radiation,

G is soil heat flux,

∆S is the time rate of change in heat stored in the 

vegetation canopy,

H is sensible heat flux, and 

LE is latent heat flux.

The left-hand side of this equation is the available 

energy, and the right-hand side is the turbulent flux. 

These fluxes are shown schematically with their 

typical positive daytime directions in figure 8. Net 

radiation, Rn, is equal to incoming short-wave and 

long-wave radiation minus outgoing short-wave and 

long-wave radiation. The effect of net radiation is to 

heat the surface warmer than both the overlying air 

and the subsurface soils. Soil heat flux, G, is the heat 

energy that moves from the surface into the subsurface 

soil by conduction. Sensible heat flux, H, is the heat 

energy that moves from the surface into the overlying 

air due to the temperature difference between them. 

Latent heat flux, LE, is the latent energy that moves 

from the surface into the overlying air as evaporation. 

Here, L is the latent heat of vaporization, defined 

above, and E is the mass flux of water vapor in grams 

per square meter per second, so that the product of L

and E (LE) is an energy flux in watts per square meter 

(a watt is one joule per second). Because L is roughly 

a constant (it varies only slightly with temperature), it 

is the constant of proportionality between the mass 

and energy fluxes associated with the evaporation of 

water. (The symbols ET and E are conceptually identical, referring to the mass flux of evaporating water. 

In this report, E is used for 30-min fluxes, in grams per 

square meter per second, and ET is used for longer 

intervals, converted into inches per day or year, 

Rn – G – ∆S = H LE +

Rn

H

LE

G

∆S

SURFACE ENERGY BALANCE

Rn – G – ∆S = H + LE SOIL

HEAT

FLUX

CHANGE IN

STORAGE

NET

RADIATION

SENSIBLE

HEAT

FLUX

LATENT

HEAT

FLUX

Humidity

Temperature

Figure 8. Schematic of the energy balance of a vegetated surface.
DATA COLLECTION AND METHODS 17

over the study surface). Both H and LE occur through 

turbulent eddy transport, a combination of convectively and mechanically generated turbulence. As 

water availability of a vegetated surface decreases, less 

of the turbulent flux occurs as LE and more occurs as 

H. The storage term, ∆S, is the change in heat energy 

stored in the plant canopy during the measurement 

period due to a change in its temperature. It is usually 

much smaller than the other terms in equation 1. 

During typical daytime conditions, the major terms all 

have positive values and move in the directions shown 

in figure 8. At night, typically Rn, G, and H reverse 

direction (and have negative values), and LE is approximately zero.

Detailed ET data were collected at two sites 

within the watershed: a lodgepole forest site and a 

grassland meadow site. Two different micrometeorological methods were used at the two sites, primarily 

because of equipment availability. The eddycorrelation (EC) method (Swinbank, 1951) was used 

at the forest site, and the Bowen-ratio (BR) method 

(Bowen, 1926) was used at the meadow site. 

Extrapolation of ET measurements to other parts 

of the basin was attempted using the sap-flow method 

(Granier, 1985), a less expensive and more portable 

method than either EC or BR. Sap-flow sensors were 

installed at the forest site during March 2000 to 

measure the rate of water flow in the tree trunks. The 

intent was to then install additional sap-flow sensors 

at other sites in the watershed to develop a relation 

between ET at the forest site and ET at other sites. 

The sap-flow sensors did not work properly, and they 

produced anomalous data. Consequently, only limited 

quantitative sap-flow data were recovered, but the 

sensors did provide fairly reliable estimates of the 

onset and cessation of transpiration by the lodgepole 

pine trees at the forest site.

The forest site is collocated with RG16 

(fig. 7, table 2) in a lodgepole forest at an elevation 

of 8,180 ft. Sensors used to collect data were located 

on and around a 60-ft-tall, triangular steel latticework tower (Rohn 45G) of the type used to support 

antennae. Observations at the site indicate that the 

mean height of the forest is 39 ft, and the forest canopy 

cover was estimated to be 60–70 percent. The forest 

extends for at least 0.25 mi in all directions except to 

the southwest. The forest is typical of lodgepole stands 

in the watershed. Slope and aspect of the land surface 

at the site are 3.75° and N14°E, respectively. Soil at 

the site is a fine to medium sand, about 9 inches deep, 

underlain by decomposed granite. Tree roots extend 

into the granite to a depth of about 2 ft, although fine 

roots may extend deeper.

Data were measured at the forest site by using 

electronic sensors, and data summaries (means, covariances, standard deviations, vector sums) were stored 

digitally at 30-minute intervals using four automatic 

data loggers. The loggers are designated “eddycorrelation (EC),” “meteorological (MT),” “energybalance (EB),” and “sap flow (SF)” (table 4). Eddycorrelation sensors were sampled every 0.125 second; 

all other sensors were sampled every 10 seconds. 

Data summaries were transferred to a storage module, 

a floppy disc, and a computer at monthly intervals. 

Eddy-correlation data collection began on day of 

year (DOY) 34 (February 3), 1999 at 4 p.m. ET values 

for DOY’s 1 through 34, 1999, were estimated to be 

0.01 inch per day, which is roughly equal to the mean

ET during the same DOY’s in 2000 and 2001. This 

estimate was made to facilitate computation of a 

1999 yearly total ET value. Collection of meteorological and energy-balance data began on DOY 140 

(May 20), 1999, at 7:30 p.m., but the initial data 

stored on the MT data logger were accidentally overwritten, so those data began on DOY 149 (May 29), 

1999, at 7:00 a.m. Soil moisture values prior to 

DOY 149 were estimated to facilitate subsequent 

water-balance computations. Sap-flow data began 

on DOY 88 (March 28), 2000. Results are reported on 

data collected at this site from the above times through 

DOY 365 (December 31), 2001, at 12:00 p.m. Sensor 

types and heights, measured variables, and data-logger 

assignments are listed in table 4. A photograph of the 

eddy-correlation evapotranspiration tower installation 

is shown in figure 9.

The meadow site is collocated with rain gage 

RG17 (fig. 7, table 2) in a native grass meadow at 

an elevation of 7,770 ft. This site is about 3.25 mi 

northeast of the forest site. Sensors used to collect 

data were located on or around a 6-ft tripod. Average 

height of grass in the meadow was about 6 inches. 

The tripod was located near the middle of the meadow, 

which is about 1.2 mi long by 0.2 mi wide, with the 

long dimension trending north-northwest to southsoutheast. Most of the grass in the meadow is typical 

of that found elsewhere in the watershed; the grass is 

not exceptionally well watered and vigorous such as 

low-lying meadow grasses along flood plains of the 

major creeks; nor is it overly dry, such as the grass 

in the high meadows in the watershed. A small,
18 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

intermittent creek runs south to north near the east 

edge of the meadow, about 400 ft east of the tripod. 

The grass within about 30 ft of the creek (the riparian 

zone) was much more lush and green than the rest of 

the meadow during much of the growing season. Slope 

and aspect of the land surface at the site are about 7°

and N50°E, respectively. Soil at the site is a silty loam 

at least 2 ft deep, underlain by decomposed granite. 

Grass roots probably extend about 10 inches below 

land surface.

Data measurement, storage, and transport 

at the meadow site were similar to those operations 

at the forest site. Sensors were sampled every 10 

seconds, and data summaries were stored digitally 

at either 15- or 30-minute intervals, all on one data 

logger. Collection of Bowen-ratio and associated 

data began on DOY 154 (June 2), 2000, at 6:30 p.m. 

Results are reported on data collected from this time 

through DOY 365 (December 31), 2001, at 12:00 p.m. 

Sensor types and heights and measured variables are 

listed in table 5. A photograph of the Bowen-ratio 

evapotranspiration tripod installation is shown in 

figure 10.

Precipitation was measured at both ET sites 

using tipping-bucket rain gages (RG16 at the forest site, 

RG17 at the meadow site, table 2); however, these gages 

provide less than ideal measurements of snowfall for 

two reasons. First, the snowfall usually is not measured 

when it falls but rather when it melts. Second, snowfall 

accumulations greater than about 3 inches in depth 

probably overtop the gage and are undermeasured. 

Therefore, snowfall at both sites was estimated using 

two weighing-bucket precipitation gages. The first 

weighing-bucket gage (RG11, table 2, fig. 7) was 

located about 1.4 mi northwest of the forest site. Data 

collection at this gage began on November 25, 1998, 

well before data collection began at the forest site. 

Snowfall amounts from RG11 were multiplied by an 

adjustment factor to account for differences in measured 

precipitation between the RG11 site and the forest site. 

The factor was determined by comparing rainfall data 

from both sites collected between DOY 134 (May 14), 

2001, and DOY 327 (November 23), 2001. During 

this calibration period, both gages were functioning reliably and no overtopping occurred. Running totals of the 

two gages during this period were highly correlated 

Table 4. Sensor type, data loggers, sensor heights, and measured variables at forest site

[EC, eddy correlation; MT, meteorological; EB, energy balance; SF, sap flow; TDR, time-domain reflectometry; negative heights are depths below land 

surface; parenthetical numbers refer to number of sensors; ft, feet)]

Sensor type

(number of sensors) Data logger Sensor height(ft) Measured variables

Sonic anemometer EC 57.1 Orthogonal windspeed components, air temperature

Krypton hygrometer EC 57.1 Vapor density fluctuations

Thermistor EC 4.92 Data logger temperature

Temperature-humidity probe MT 51.8 Air temperature, relative humidity

Infrared thermometer MT 50.5 Leaf (needle) surface temperature

Cup anemometer MT 56.1 Windspeed

Wind vane MT 56.1 Wind direction

Tipping-bucket rain gage MT 33.1 Rainfall

Leaf wetness sensor MT 13.3 Presence of water on leaves (needles)

Thermistor MT –0.49 Soil temperature

Thermistor MT –1.15 Soil temperature

TDR Probe MT –0.16 Soil moisture

TDR Probe MT –0.75 Soil moisture

Net radiometer EB 53.5 Net radiation

Pyranometer EB 54.1 Solar radiation

Thermocouples (4) EB 12.8 to 18.0 Bole temperature

Soil heat flux plates (3) EB –0.26 Soil heat flux at 3.15 inches depth

Thermocouples (12) EB 0 to –0.26 Soil temperature in top 3.15 inches of soil

Sap flow sensors (8) SF 4.59 Sap velocity
DATA COLLECTION AND METHODS 19

Figure 9. Eddy-correlation evapotranspiration tower at forest site.

(r2 = 0.9978, standard error = 0.151 inch). An adjustment factor of 1.03 was computed as the ratio of the 

RG16 total to the RG11 total during the calibration 

period. This relation was used to estimate snowfall at 

the forest site during 1999 and 2000. On December 6, 

2000, the second rain gage, a weighing-bucket gage, 

(RG18, table 2) was collocated with RG16 at the forest 

site to measure snowfall at that site directly. A comparison between RG18 and RG16 during the 2001 calibration period indicated an adjustment factor for RG18 of 

1.15 (r2

 = 0.9991, standard error = 0.101 inch). This 

factor was unexpectedly larger than 1.00, considering 

that RG16 and RG18 were separated by only about 

200 ft and both gages were calibrated prior to installation. Inspection of the data revealed that RG18, a 

previously used weighing-bucket gage, chronically 

undermeasured small rainfalls (less than about 

0.25 inch) but accurately measured larger rainfalls 

(greater than about 0.40 inch). Slightly excessive friction in the linkage mechanism could account for this 

bias. Because the standard error between RG18 and 

RG16 (0.101 inch) was significantly smaller than 

between RG11 and RG16 (0.151 inch), data from RG18 

were used to estimate snowfall at the forest site during
20 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

2001 by using the adjustment factor of 1.15. Comparisons also were made between the meadow site tippingbucket gage (RG17) and the two weighing-bucket gages 

(RG11 and RG18). RG17 was more highly correlated 

with RG11 (r2

 = 0.9972, standard error = 0.172 inch) 

than with RG18 (r2

 = 0.9965, standard error = 0.189 

inch), so RG11 data were used to estimate snowfall 

at the meadow site during 2000 and 2001 by using 

an adjustment factor of 1.003.

Surface-Water Data

Contemporary records of streamflow associated 

with this study include data from stream gages on 

Turkey Creek in the vicinity of the present gage, shortterm records from stream gages on tributaries to Turkey 

Creek, miscellaneous measurements of streamflow 

associated with water-quality sampling, and synoptic 

measurements of streamflow. All these data are available in the NWIS database.

Two stream gages on Turkey Creek were operated during this study (fig. 4). The present stream 

gage, station 06710992, Turkey Creek near Indian 

Hills, has data available beginning April 13, 2001. 

The present gage replaces station 06710995 (shown 

Table 5. Sensor type, heights, and measured variables at 

meadow site

[Negative heights are depths below land surface; parenthetical numbers 

refer to number of sensors; ft, feet)

Sensor type

(number of sensors)

Sensor 

height

(ft)

Measured variables

Net radiometer #1 4.66 Net radiation (level)

Net radiometer #2 4.79 Net radiation (normal 

to land surface)

Pyranometer 5.25 Solar radiation

Cup anemometer 5.74 Windspeed

Wind vane 5.74 Wind direction

Leaf wetness sensor 4.17 Presence of water 

on leaves

Temperature-humidity 

probe

6.52 Air temperature, relative 

humidity, upper

Temperature-humidity 

probe

3.48 Air temperature, relative 

humidity, lower

Tipping-bucket rain gage 1.41 Rainfall

Soil heat flux plates (3) –0.16 Soil heat flux at 

1.97 inches depth

Thermocouples (12) 0 to –0.16 Soil temperature in top 

1.97 inches of soil

Thermistor 0.98 Data logger temperature

as SWA01 in fig. 4), Turkey Creek at mouth of canyon 

near Morrison, Colorado (operated from April 1, 1998, 

through April 13, 2001), which was discontinued due 

to complications related to streamflow diversions and 

local anomalous conditions at the gage described in 

the “Surface-Water Conditions” section. Records for 

station 06710995 are affected by diversions from the 

Independent Highline ditch; in addition, records from 

06710995 are estimated for April 15, 2000, to June 1, 

2000. Additional short-term records of streamflow in 

the Turkey Creek watershed from four tributaries for 

the spring of 2001 are discussed in the “Surface-Water 

Conditions” section.

In addition to records of streamflow from the 

stream gages described above, miscellaneous measurements of streamflow were made when surface-water 

samples were collected in water year 1999; locations 

and identifiers for these miscellaneous measurements 

are in figure 4 and table 6. Additional synoptic 

measurements of streamflow were made periodically 

during the summer of 2001 at as many as 29 sites. 

This includes sites only used for synoptic measurements (SN sites in table 6) and some additional sites 

that, along with results of synoptic measurements, 

are discussed in the “Surface-Water Conditions” 

and “Runoff Modeling” sections.

Ground-Water Data

Ground-water data were collected as part of 

this study in addition to historical water-level data 

collected in the 1970’s and well-construction data 

available from the SEO. These additional data include 

time-series water-level data and a fall 2001 synoptic 

measurement of water levels in a network of wells.

Water levels were measured monthly, by volunteers, at 15 monitoring wells distributed in and near 

the watershed beginning about 1999 (locations, 

fig. 11). These wells are no longer used by homeowners for various reasons and were volunteered to 

the study as reliable indicators of static water levels 

in parts of the watershed. Of these wells, five are 

USGS monitoring wells constructed in the 1970’s 

(local identifiers MH1, MH5, MH8, MH9, and MH10) 

completed in bedrock and previously sampled for 

selected water-quality parameters and water levels 

(Hofstra and Hall, 1975a; 1975b). All of these waterlevel data are available from the USGS NWIS database. Three of the non-USGS wells are pre-1950, 

shallow, hand-dug wells (local identifiers MH2, 

MH12, and MH13). The remaining wells are
DATA COLLECTION AND METHODS 21

completed at various depths. Table 7 lists wellconstruction information available for these monthly 

water-level monitoring wells. Beginning May 2001 

and through September 2001, time-series water-level 

data, at a time step of 60 minutes, were collected at a 

subset of 3 of the 15 monthly water-level monitoring 

wells (local identifiers MH1, MH5, and MH8). 

Contemporary water levels were measured 

at 131 wells during September 24–October 4, 2001. 

Most of these measurements were made in domestic 

wells currently in use. The measuring devices were 

disinfected and rinsed between measurements. Information about domestic water usage on the day of 

measurement was recorded if available. Locations 

of these wells are shown in figure 11, and the results 

of the measurements are listed in the Appendix 

(table A4).

Water-Quality Data

Water-quality data describing water-quality 

properties and concentrations of constituents in 

surface water and ground water were collected at 

about quarterly intervals for 1 year (water year 1999), 

beginning in fall 1998, at 22 surface-water sites and 

at 110 wells and springs and in the watershed. USGS

Figure 10. Bowen-ratio evapotranspiration tripod at meadow site.
22 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

station numbers, local site identifiers, and selected 

characteristics for surface-water and ground-water 

sites that were sampled are listed in table 6 and table 8, 

respectively. These data reside in the USGS WaterQuality System of NWIS (Garcia and others, 1997). 

The locations of sampling sites are shown in figure 4 

for surface water and figure 12 for ground water. In 

most cases, USGS station numbers consist of latitude 

(6 digits), longitude (7 digits), and a 2-digit sequential 

identifier appended into a unique 15-digit number for 

each site. Other USGS station numbers are 8-digit 

downstream-order numbers that indicate the major 

Table 6. Site identifiers and selected characteristics for sites of surface-water-quality samples, short-term streamflow records, 

and synoptic streamflow measurements in the Turkey Creek watershed, Jefferson County, Colorado, 1998–2001

[Note: Local identifier (Surface-water sampling sites), SWlnn where l = character designating subbasin (fig. 4) and 

 n is a sequential number for surface-water sites in the designated subbasin; Local identifier (synoptic measurement

 sites), SNGGnn where GG indicates geology and nn is a sequential number for synoptic measurement sites in the given

 geology; USGS identifier (synoptic measurement sites) indicate latitude and longitude of synoptic measurement site;

 Contributing drainage area, area in square miles; --, no data]

-------------------------------------------------------------------------------------------------------------------------------

 Contributing

 Local USGS drainage

identifier identifier area Site name 

-------------------------------------------------------------------------------------------------------------------------------

 SURFACE-WATER SAMPLING AND MISCELLANEOUS STREAMFLOW MEASUREMENT SITES

 SWA01 06710995 47.42 Turkey Creek at mouth of canyon, near Morrison 

 SWA02 393753105102701 -- Turkey Creek above pipe above Hwy C-470 near Morriosn 

 SWA03 393753105102700 -- Inflow pipe to Turkey Creek above C-470 near Morrison 

 SWA04 393755105102500 -- Turkey Creek below pipe, above C-470, near Morrison 

 SWA05 393756105102300 50.09 Turkey Creek above Hwy C-470, near Morrison 

 SWB01 393639105135000 39.63 Turkey Creek above Parmalee Gulch at Indian Hills 

 SWB02 393540105131100 13.32 South Turkey Creek at mouth near Indian Hills 

 SWC01 393657105140300 5.66 Parmalee Gulch above mouth at Indian Hills 

 SWD01 393719105145500 2.84 Parmalee Gulch above Giant Drive at Indian Hills 

 SWE01 393714105151000 1.33 Giant Gulch at mouth at Indian Hills 

 SWF01 393536105131500 24.56 North Turkey Creek at mouth near Indian Hills 

 SWG01 393518105155700 20.57 North Turkey Creek near Wild Rose Grange near Indian Hills 

 SWH01 393455105171200 1.92 North Turkey Creek tributary near Danks Dr near Indian Hills 

 SWI01 393338105190600 1.47 North Turkey Creek tributary at Blue Creek Rd near Aspen Park 

 SWJ01 393337105190400 9.48 North Turkey Creek above Blue Creek Rd trb near Aspen Park 

 SWK01 393207105184400 4.32 North Turkey Creek above Shadow Mountain Dr above Aspen Park 

 SWK02 393206105184100 3.18 North Turkey Creek tributary at Shadow Mountain Drive above Aspen Park 

 SWL01 393506105130700 2.00 Iowa Gulch at mouth near Indian Hills 

 SWM01 393505105130500 10.21 South Turkey Creek above Iowa Gulch near Indian Hills 

 SWN01 393339105131500 1.10 South Turkey Creek tributary above Flint Lane near Indian Hills 

 SWO01 393339105131400 7.47 South Turkey Creek above Flint Ln near Indian Hills 

 SWP01 393246105155200 2.68 South Turkey Creek above Meyer Rnch Pk near Aspen Park

 SHORT-TERM STREAMFLOW RECORD SITES

 STR-1 393203105221600 0.27 North Turkey Creek upper tributary near Aspen Park (Pikes Peak Granite)

 STR-2 393210105205500 2.23 North Turkey Creek tributary above Warhawk Road near Aspen Park (fault-zone rocks)

 STR-3 393141105200500 0.96 North Turkey Creek tributary near Aspen Park (intrusive rocks)

 STR-4 393443105165800 1.10 North Turkey Creek tributary near Gartner Drive near Aspen Park (intrusive rocks)

 SYNOPTIC STREAMFLOW MEASUREMENT SITES

 SNDIV 393714 1051155 -- Diversion from Turkey Creek near Willow Cr subdivision

 SNCG1 393202 1052218 0.27 Upper tributary to North Turkey Creek above Aspen Park

 SNCG2 393213 1052209 0.27 North tributary to North Turkey Creek above Aspen Park

 SNFZ1 393210 1051658 2.33 North Turkey Creek above Warhawk Rd near Aspen Park

 SNFZ2 393114 1051835 1.72 Tributary to North Turkey Creek tributary at Conifer High School

 SNGN6 393529 1051305 0.69 Tributary to South Turkey Creek at West Ranch near Tiny Town 

 SNGN9 393242 1051553 2.90 Tributary to South Turkey Creek below Meyer Ranch near Aspen Park 

 SNGN10 393658 1051413 0.41 South Tributary to Parmalee Gulch near US 285 

 SNSP1 393151 1051815 0.70 Tributary to North Turkey Creek at Light Lane near Aspen Park

 SNSP2 393141 1052005 0.96 Tributary to North Turkey Creek above Aspen Park

 SNSP4 393443 1051658 1.00 Tributary to North Turkey Creek near Gartner Dr n Aspen Park 

 SNQA2 393453 1051737 0.65 Tributary to North Turkey Creek near Danks Drive 

 SNQS1 393417 1051838 0.46 Tributary to North Turkey Creek on Grizzly Drive 

 SNQS2 393435 1051845 0.37 Tributary to North Turkey Creek near Red Fox

 SNSG3 393815 1051426 0.41 Tributary to North Turkey Creek near Lone Pine Estates

 SNSG4 393716 1051454 1.34 Giant Gulch at mouth

-------------------------------------------------------------------------------------------------------------------------------
DATA COLLECTION AND METHODS 23

river basin (Turkey Creek is part of the Missouri River 

Basin, which is drainage basin number 06) and a 

number indicating that site’s downstream order in relation to other sites in the drainage (6 digits). Local site 

identification numbers were typically assigned on the 

basis of 16 subwatersheds identified by topographic 

boundaries, in alphabetical sequence (A–P), starting at 

the mouth of the watershed. Surface-water sites are 

prefixed SW and ground-water sites are prefixed GW. 

The samples were collected according to applicable 

protocols described in the National Field Manual for 

the Collection of Water-Quality Data (U.S. Geological 

Survey, 1997–present). Hundreds of quality-control 

samples were collected as part of these sampling activities; the results of the quality-control samples are 

described in the Appendix and listed in tables A1–A3. 

Table 9 lists water-quality properties and constituents 

included in the analyses.

A limited number of additional miscellaneous 

samples were collected in water years 2000 and 2001 

following the initial study sampling period in water 

year 1999. Included in the miscellaneous sampling 

are samples collected for tritium analysis in 

November 2000, samples collected for a suite of 

organic compounds associated with wastewater 

compound in April and September 2001, and samples 

collected concurrently with the wastewater-compound 

samples for analysis of major ions and nutrients. 

Results for selected major ions (fluoride, bromide) 

and nitrate plus nitrite are reported for samples

Parmalee Gulch

S. Turkey Creek

N. Turkey Cr

Giant Gulch

Turkey Creek Iowa Gulch

Lone Pine Estates

Wild Rose Grange

Marshdale

Tiny Town

Indian

Hills

Fenders

Phillipsburg

Homewood Park

Oehlmann

Park

Conifer

8

To Morrison

C470

Shadow Mountain Road

N. Turkey Creek Rd

Parma lee Gulch

Road

285

285

Marshdale

D A

B

E

D C

F

L

M

H

P

G

I

J

K

N

O

39°32'24"

39°30'36"

39°34'12"

39°36'

39°37'48"

105°23'24" 105 105°21'36" °19'48" 105°18' 105°16'12" 105°14'24" 105°12'36" 105°10'48"

EXPLANATION

Study area

Subbasins

Drainage

Roads

Subbasin code

Population centers

Monitoring well site

Synoptic measure-

 ment site

0

0 0.5 1 1.5 2 2.5 3 KILOMETERS

0.5 1 1.5 2 2.5 3 MILES

MH8

MH7

MH5

MH3 MH4

MH2

MH12

MH11

MH10

MH6s MH6p

MH6sf

MH1

MH13

Base modified from U.S. Geological Survey

digital data for 1:24,000 maps

Figure 11. Locations of water-level monitoring wells.
24 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

collected concurrently with the April 2001 

wastewater-compound samples. The major ion 

sampling was a part of a larger quarterly sampling 

effort conducted by Jefferson County Health 

Department personnel at selected wells, in cooperation with Colorado Department of Public Health and 

Environment. Local identifiers for sites sampled and 

analyses completed at each site are listed in table 10.

Tritium concentrations in the watershed were 

evaluated on the basis of 24 ground-water environmental samples, and 5 duplicate samples were 

collected in 1-L glass bottles for tritium analysis 

during November 2000. Zero head-space in sample 

bottles was maintained and no additional filtration 

or preservation was done in the field. Groundwater samples for tritium analysis were collected by 

Jefferson County Health Department personnel from 

outside spigots supplied by domestic wells. Bottles 

were sent by Jefferson County Health Department 

personnel to the Environmental Isotope Laboratory, 

University of Waterloo, in Ontario, Canada, for analysis of tritium content (Roy Laws, Jefferson County 

Health Department, oral commun., October 2001).

The occurrence of compounds indicative of 

human wastewater in the watershed was evaluated on 

the basis of wastewater-compound samples collected 

in April 2001 (eight ground water, four surface water, 

and two field blanks) and September 2001 (three 

surface water and one field blank). Quality-assurance 

samples associated with the wastewater-compound 

analyses included three field blanks, three laboratory 

blanks, and three laboratory spikes. Ground-water 

samples for wastewater-compound analysis were 

collected from outside spigots supplied from domestic

Table 7. Well-construction details and miscellaneous data for ground-water level monitoring wells in the Turkey Creek 

watershed, Jefferson County, Colorado, 1998–2001

[ID, identifier; OB, overburden thickness; TPerf, top depth of perforation below land surface; Bperf, bottom depth of perforation

 below land surface; TD, total depth of well; gpm, gallons per minute; SWL, static water level; MP, measuring point for water levels in

 feet above land surface; Meta, metamorphic; SC, specific conductance; Temp, water temperature; Ave. WL Feb, average water level for month

 of February; nd,not determined; μS/cm, microsiemens per centimeter at 25o Celsius; NGVD29, National Geodetic Vertical Datum 1929]

---------------------------------------------------------------------------------------------------------------------------------

 Reported

Local ID Permit number Permit date Latitude Longitude OB Well diameter Casing TPerf BPerf TD yield

 or USGS NWIS ID (inches) (inches) type (feet) (feet) (feet) (gpm)

---------------------------------------------------------------------------------------------------------------------------------

MH1 SC00507006CDD 6/21/73 393820 1051612 10 6 steel nd 22 180 0.2

MH2 No permit-Hand dug nd 393604 1051320 0 36 rock nd nd nd nd

MH3 59454 4/16/74 393513 1051813 nd nd nd nd nd 150 11

MH4 31708 5/25/76 393459 1051657 0 nd nd 80 200 200 2

MH5 SC00607102BBD 6/21/73 393350 1051844 5 6 steel nd 23 140 0.352

MH6.1 67101BAC nd 393348 1051714 1 nd nd nd nd nd nd

MH6.2 14341 1/26/63 393344 1051714 1 nd nd nd nd 82 1

MH6.3 73389 6/01/25 393342 1051715 0 nd nd nd nd 100 15

MH7 184948 12/19/94 393332 1051508 5 6 steel/pvc 225 505 505 50

MH8 SC00607007AAA 7/31/73 393301 1051532 5 6 steel nd 23 70 6.8 

MH9 SC00607013CCC 8/02/73 393120 1051106 10 6 steel nd 18 160 0.443

MH10 SC00607125DAA 6/22/73 392958 1051646 40 6 steel nd 43 220 0.091

MH11 3672 5/24/64 393112 1051821 nd nd nd 74 209 227 5

MH12 No permit-Hand dug nd 393143 1051954 nd 36 rock nd nd nd nd 

MH13 No permit-Hand dug nd 393717 1051453 nd 36 rock nd nd nd nd

=======================================================================================================================

Local ID SWL Water level MP Elevation subbasin Rock type SC Temp Date Ave. WL Feb (feet) 

 (feet) Date (feet) (ft NGVD29) (μS/cm)(deg F) 1999 and 2000 1973 - 1983

---------------------------------------------------------------------------------------------------------------------------------

MH1 18.24 12/11/73 1.2 7,310 D Meta 390 9.5 12/11/73 18.2 18.3 

MH2 nd nd 1.0 6,900 B Meta nd nd nd 13.9 nd 

MH3 40 4/16/74 0.5 7,751 G Meta nd nd nd 9.30 nd 

MH4 25 nd 0.0 7,672 G Meta nd nd nd 95.9 nd 

MH5 28.14 12/11/73 2.0 7,900 G Meta 170 7.0 12/11/73 30.8 31.4 

MH6.1 nd nd 0.5 8,375 H Igneous nd nd nd 8.40 nd 

MH6.2 10 1/26/63 0.0 8,352 H Igneous nd nd nd 8.51 nd 

MH6.3 nd 6/1/25 0.2 8,340 H Igneous nd nd nd 23.8 nd 

MH7 25 1/13/97 1.17 8,337 N Meta nd nd nd 61.2 nd 

MH8 12.45 12/12/73 1.3 8,050 O Meta 160 8.5 11/6/73 15.1 11.7 

MH9 15.97 12/10/73 1.33 6,720 O Meta 305 8.0 11/6/73 17.4 15.6 

MH10 22.14 12/12/73 1.5 7,950 K Igneous 355 5.5 12/12/73 21.8 21.8 

MH11 30 5/24/64 1.5 8,477 K Meta nd nd nd 19.3 nd 

MH12 nd nd 2.5 8,187 K Igneous nd nd nd 7.65 nd 

MH13 nd nd 2.5 7,279 E Igneous nd nd nd 9.40 nd 

---------------------------------------------------------------------------------------------------------------------------------
DATA COLLECTION AND METHODS 25

Table 8. Site identifiers and selected characteristics for ground-water-quality sampling sites 

in the Turkey Creek watershed, Jefferson County, Colorado, 1998–2000

[Note: SEO, State Engineers Office; Yield, well yield in gallons per minute as reported to State 

 Engineers Office; Date of measurement, in month/day/year, refers to depth to water measurement; 

 all depths reported in feet below land surface; --, not available; *, spring; Elevation, elevation 

 in feet above sea level;** well sampled weekly for specific conductance in fall 2000 and spring 2001]

------------------------------------------------------------------------------------------------------

 Depth to

 SEO screen

 Local USGS permit Ele- Total ----------- Depth to Date of

identifier identifier number vation depth Top Bottom Yield water measurement 

------------------------------------------------------------------------------------------------------

 GWA01** 393713105131401 97069 6585 540 -- -- 15 150 5/ 1/78 

 GWA02** 393712105131900 42209 6630 280 -- -- 0 0 8/ 4/70 

 GWA03* 393733105111700 -- 7556 0 -- -- 0 -- -- 

 GWB01 393602105133100 77536 6955 350 -- -- 2.5 46 6/12/92 

 GWB02** 393604105132200 164834 6887 420 -- -- 6.3 6 10/30/92 

 GWC01 393705105141100 61643 -- 100 -- -- 3.5 40 8/29/72 

 GWC02** 393703105145100 187422 6278 45 -- -- 15 -- -- 

 GWC99 393810105141900 141992 7794 250 -- -- 30 80 9/17/85 

 GWD01 393758105163600 44798 7565 125 -- -- 10 45 5/15/57 

 GWD02 393757105163400 46328 7738 318 -- -- 1 32 6/17/71 

 GWD04** 393813105150100 153536 7550 266 -- -- 1.47 28 -- 

 GWD05 393812105145300 -- 7698 254 -- -- -- -- -- 

 GWD06 393815105152500 -- 7430 -- -- -- -- -- 

 GWD07 393742105153700 -- 7259 -- -- -- -- -- 

 GWD08 393746105153000 -- 7230 -- -- -- -- -- 

 GWE01 393711105151000 63369 7154 363 -- -- 3 44 9/25/72 

 GWE03 393709105145300 68842 6957 150 25 145 15 15 5/17/73 

 GWF01 393528105151600 -- 7458 270 -- -- 3 60 -- 

 GWF02 393532105150500 65593 7437 280 180 280 6 65 2/26/73 

 GWF03 393554105142100 89809 7494 340 -- -- 2 105 9/ 3/77 

 GWF04 393553105142100 84734 7416 340 -- -- 3 110 9/24/76 

 GWF05 393549105142200 81233 7498 360 -- -- 5 107 11/ 3/75 

 GWF06** 393552105144200 -- 7373 200 -- -- 3 32 -- 

 GWF08 393556105144600 -- 7505 270 -- -- -- -- -- 

 GWF09 393552105143600 45921 7430 255 -- -- 2.5 37 6/17/71 

 GWF10** 393614105151800 129807 8213 325 -- -- 4 50 5/ 3/83 

 GWF11** 393518105150200 58049 7376 300 240 300 6 101 9/19/73 

 GWF12 393546105141000 81747 7158 200 -- -- 36 25 5/19/76 

 GWF13 393437105160700 109067 7727 -- -- -- -- -- 

 GWF14 393551105144700 151655 7430 563 30 290 10 79 9/15/88 

 GWF15** 393640105164400 58531 7960 170 -- -- 5 70 6/ 1/72 

 GWG01** 393308105181500 -- 8094 130 -- -- -- -- -- 

 GWG02 393404105182200 26910 7951 127 -- -- 16 -- 4/25/66 

 GWG03 393310105183200 -- 8047 -- -- -- -- -- 

 GWG04 393421105184700 -- 7758 -- -- -- -- 10/23/78 

 GWG05 393426105194300 98471 8196 240 -- -- 2.5 40 3/ 7/79 

 GWG06 393344105191600 89565 7869 175 -- -- 3 50 6/15/77 

 GWG07 393544105174100 -- 8188 -- -- -- -- 8/16/58 

 GWG08 393458105170000 -- 7697 -- -- -- -- -- 

 GWG09 393505105170400 188660 7620 260 -- -- 10 60 9/19/95 

 GWG10 393316105181400 -- 8295 -- -- -- -- -- 

 GWG11 393459105165700 31703 7733 645 -- -- 3.5 200 -- 

 GWG12 393351105184500 97386 7908 625 -- -- 2.5 280 6/ 6/78 

 GWG13 393444105173700 -- 7820 -- -- -- -- -- 

 GWH01** 393449105170100 31496 7571 160 -- -- 1.5 30 7/14/67 

 GWH02 393449105164800 8596 7772 575 380 495 1 200 12/20/75 

 GWH03** 393444105165500 107430 7741 400 -- -- -- -- -- 

 GWI01 393242105202000 83451 8564 220 -- -- 6 20 5/24/76 

 GWI02 393237105204600 79402 8590 123 43 123 12 48 11/14/75 

 GWI03 393334105192500 15137 7920 118 -- -- 21 40 5/ 9/63 

 GWI04 393300105194400 93546 8068 143 -- -- 6 35 -- 

 GWI05 393340105195000 -- 8053 -- -- -- -- 

 GWI06 393334105195100 144213 8101 243 123 223 7.5 40 8/13/86 

 GWI07 393241105203900 172590 8572 277 -- -- 10 30 9/30/93 

 GWI08 393235105204300 103219 -- -- -- -- -- 

 GWJ01** 393224105251600 181194 8689 600 -- -- 4.25 315 8/25/97 

 GWJ02** 393230105201000 94815 8500 175 100 175 4 100 11/28/77 

 GWJ03 393234105201800 109522 8641 305 165 305 5 60 9/12/79 

 GWJ04 393242105201000 79785 8465 500 380 500 0.75 175 8/17/75 

 GWJ06 393301105185700 23678 7920 25 -- -- 11 -- 5/ 7/65 
26 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

Table 8. Site identifiers and selected characteristics for ground-water-quality sampling sites 

in the Turkey Creek watershed, Jefferson County, Colorado, 1998–2000—Continued

[Note: SEO, State Engineers Office; Yield, well yield in gallons per minute as reported to State 

 Engineers Office; Date of measurement, in month/day/year, refers to depth to water measurement; 

 all depths reported in feet below land surface; --, not available; *, spring; Elevation, elevation 

 in feet above sea level;** well sampled weekly for specific conductance in fall 2000 and spring 2001]

-------------------------------------------------------------------------------------------------------

 Depth to

 SEO screen

 Local USGS permit Ele- Total ----------- Depth to Date of

identifier identifier number vation depth Top Bottom Yield water measurement 

-------------------------------------------------------------------------------------------------------

 GWJ07 393259105185700 -- 7918 -- -- -- -- -- 

 GWJ08 393311105184100 -- 8059 -- -- -- -- -- 

 GWJ09 393308105184900 118007 7987 242 142 242 21.5 84 11/27/81 

 GWJ10 393314105190200 -- -- -- -- -- -- 

 GWK01 393154105220100 187230 9143 300 180 280 60 80 11/11/96 

 GWK02 393209105220600 97263 8938 300 200 300 3 50 5/ 5/78 

 GWK03 393208105221600 89745 9129 320 -- -- 15 81 7/22/77 

 GWK04** 393151105220800 187230 9227 300 -- -- 60 51 2/13/97 

 GWK05 393237105222900 170503 9915 542 -- -- 3.6 192 10/ 4/95 

 GWK06 393103105184800 -- 8502 210 -- -- -- 160 -- 

 GWK07 393151105192200 79825 8171 280 -- -- 0.5 36 6/29/77 

 GWK08 393206105204800 153657 8402 15 -- -- -- -- -- 

 GWK09 393243105214500 31423 8827 220 -- -- 3 100 7/ 6/67 

 GWK10 393153105192400 194248 8168 26 -- -- 15 0 --

 GWK11 393153105192401 194248 8196 80 -- -- 70 8 1/24/97 

 GWL01 393352105150000 176233 8258 810 600 810 1.5 700 1/19/94 

 GWM02 393418105131000 12868 7159 350 -- -- 15 100 2/14/85 

 GWM03 393413105132200 -- 7254 -- -- -- -- -- 

 GWM04 393413105135800 102558 7452 300 -- -- 1 25 10/11/78 

 GWM05 393424105134800 115646 7442 305 145 305 12 40 8/19/80 

 GWM06** 393423105130400 59071 7086 54 -- -- 5 -- 9/23/56 

 GWM07** 393401105124600 107190 7278 500 -- -- 0 0 9/19/79 

 GWM08 393400105125900 49818 7255 283 43 283 0.6 14 3/26/72 

 GWM09* 393426105130000 -- 7102 0 -- -- -- -- -- 

 GWM10 393457105131600 156284 7007 605 160 605 4 40 12/ 8/89 

 GWM11 392936105231600 -- -- -- -- -- -- 

 GWN01** 393308105145500 102180 7888 280 -- -- 7.5 40 9/26/79 

 GWN02 393342105131800 21039 90 50 90 3 25 8/12/64 

 GWN03 393337105150700 96531 245 -- -- 6 140 2/25/78 

 GWN04 393331105145100 193271 405 200 400 18 80 3/15/96 

 GWN99 393341105131500 -- 7178 -- -- -- -- -- 

 GWO02** 393252105154800 44362 7911 288 -- -- 1.25 10 2/ 9/71 

 GWO03 393233105152400 121662 7933 0 -- ---- -- 

 GWO04 393238105152000 69768 7760 144 44 144 1.25 35 9/11/73 

 GWO05 393245105145000 -- 7925 -- -- -- -- -- 

 GWO06 393231105144000 75027 7839 325 100 325 2 60 6/26/74 

 GWO07 393206105141800 67433 8023 245 165 245 10 175 2/21/73 

 GWO08 393226105151600 22265 7879 316 -- -- 1 6 11/ 2/64 

 GWO09 393139105141200 64435 8398 195 45 195 1.5 80 2/ 8/73 

 GWO10** 393115105141100 41782 8149 75 30 70 3 60 8/15/70 

 GWO11 393144105135600 119397 8517 575 475 575 15 100 4/27/83 

 GWO12** 393122105142100 -- 8490 -- -- -- -- -- 

 GWO13 393236105142900 192230 8652 400 280 380 0.25 50 11/23/97 

 GWP01 393245105175800 187284 7900 600 -- -- 0.48 41 1/23/97 

 GWP02 393249105174600 -- 8384 475 -- -- 3 -- -- 

 GWP03 393227105181600 136487 8238 350 -- -- -- -- -- 

 GWP04** 393204105180200 191850 8290 377 -- -- 3.5 100 4/19/96 

 GWP05** 393244105172600 58806 8218 320 -- -- 1 200 7/11/73 

 GWP99 393237105162900 172122 7977 190 -- -- 1.5 150 -- 

 GWX01 393031105211000 153691 9396 520 400 500 1.25 100 4/29/89 

--------------------------------------------------------------------------------------------------------

 
DATA COLLECTION AND METHODS 27

wells by Jefferson County Health Department personnel 

concurrently with inorganic samples. All surfacewater sample bottles were filled by the dip method by 

USGS personnel. Wastewater samples were transported 

to the USGS National Water Quality Laboratory 

(NWQL) in Denver, Colo., for custom gas chromatograph analysis.

Major ion and nutrient samples were collected 

with the wastewater compound samples by using the 

same USGS protocols used in the water year 1999 

sampling. Analytical determinations also were made at 

the U.S. Environmental Protection Agency Region VII 

laboratory except for low-level bromide determinations, 

which were made at the NWQL.

Runoff Modeling Methods

Runoff modeling was used in this study to 

help estimate the amount of precipitation received by 

the Turkey Creek watershed that recharges the groundwater system, to characterize how much of the precipitation leaves the watershed as evapotranspiration or 

components of streamflow, and to develop estimates 

of water-balance terms. The runoff model selected for 

use is in this study is the Precipitation-Runoff 

Modeling System (PRMS) (Leavesley and others, 

1983) as implemented by the Modular Modeling 

System (MMS) (Leavesley and others, 1996). PRMS 

is a modularly designed, distributed-parameter,

Parmalee Gulch

S. Turkey Creek

N. Turkey Cr

Giant Gulch

Turkey Creek Iowa Gulch

Lone Pine

Estates

Wild Rose Grange

Marshdale

Tiny Town

Indian

Hills

Fenders

Phillipsburg

Homewood Park

Oehlmann

Park

Conifer

8

To Morrison

C470

Shadow Mountain Road

N. Turkey Creek Rd

Parma lee Gulch

Road

285

285

Marshdale





D A

B

E

D

C

F

L M

H

P

G

I

J

K

N

O

39°32'24"

39°30'36"

39°34'12"

39°36'

39°37'48"

105°23'24" 105 105°21'36" °19'48" 105°18' 105°16'12" 105°14'24" 105°12'36" 105°10'48"

EXPLANATION

Study area

Subbasins

Drainage

Roads

Subbasin code

Population centers

Ground-water site

 and identifier

0

0 0.5 1 1.5 2 2.5 3 KILOMETERS

0.5 1 1.5 2 2.5 3 MILES

GWP02

GWN01

GWO02

GWO03

GWO04

GWO08

GWP03

GWP04

GWP05

GWK07

GWK10

GWK11

GWP99

GWA01 GWA02

GWC01

GWC02

GWC99

GWD01

GWD02

GWD03

GWD04

GWD05 GWD06

GWD07

GWD08

GWE03

GWA03

GWB01

GWB02

GWF01

GWF02

GWF04

GWF05

GWF06

GWF08 GWF09 GWF10

GWF11

GWF12

GWF14

GWM03

GWM04

GWM05 GWM06

GWM07

GWM08

GWM09

GWM10

GWN02

GWN99

GWM11

GWL01

GWN03

GWN04

GWO05

GWO06

GWO07

GWO13

GWO09

GWO10

GWO11

GWO12

GWX01

GWI08 GWJ02

GWJ03

GWK01

GWK02 GWK03

GWK04

GWK05

GWK08

GWJ01

GWG01

GWG03

GWI01

GWI02

GWI04 GWI07 GWJ06 GWJ07

GWJ09

GWK09

GWJ04

GWG06

GWI03

GWI05

GWI06

GWJ08 GWG10

GWG12

GWG02

GWG05 GWG04

GWG13

GWF13

GWG08

GWG09

GWG11

GWH01

GWH02

GWH03

GWF03

GWF15

GWG07

GWG07

Figure 12. Location of ground-water sampling sites.
28 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

physically based, deterministic model that characterizes the many physical processes involved in watershed runoff. MMS provides a computer environment 

that, among other capabilities, implements PRMS and 

many pre- and post-processing capabilities that facilitate watershed analyses.

For runoff modeling discussions in this report, 

the term “water balance” is used to indicate a description of the fate of precipitation in the watershed. A 

water balance is an accounting of system inputs 

and outputs that typically is balanced by a change 

in storage term and expressed as equation 2: 

(2)

where

P is precipitation falling on the watershed, 

ET is evapotranspiration leaving the watershed, 

Q is streamflow leaving the watershed, and 

S is change in watershed storage. 

In this formulation, change in storage includes 

changes in the amount of ground water in the watershed 

and changes in the amount of soil moisture in the 

watershed.

A principal advantage of using a model such 

as PRMS is that values for all water-balance terms are 

typically calculated by the model. The general form 

for a water-balance equation used in equation 2 is, 

∆S P ET Q = – – indeed, general. That is, each of the terms represented 

∆

Table 9. Water-quality properties and constituents included in analyses in water year 1999

[Note: cfs, cubic feet per second; μS/cm, microsiemens per centimeter at 25o Celsius; mg/L, milligrams per liter; 

μg/L, micrograms per liter; --, not applicable; oC, degrees Celsius] 

--------------------------------------------------------------------------------------------------------------------

 USGS USGS 

parameter Water-quality parameter Water-quality 

 code property or constituent Reporting units code property or constituent Reporting units 

--------------------------------------------------------------------------------------------------------------------

 PHYSICAL PROPERTIES MINOR ELEMENTS 

 

 00061 Discharge cfs 01106 Aluminum (dissolved) μg/L 

 00095 Specific conductance uS/cm at 25oC 01105 Aluminum (total) μg/L 

 00400 pH standard units 01095 Antimony (dissolved) μg/L 

 00010 Temperature degrees Celsius 01097 Antimony (total) μg/L 

 00300 Dissolved oxygen mg/L 01000 Arsenic (dissolved) μg/L 

 00900 Hardness as CaCO3, total mg/L 01002 Arsenic (total) μg/L 

 01005 Barium (dissolved) μg/L 

 MAJOR IONS 01007 Barium (total) μg/L 

 01010 Beryllium (dissolved) μg/L 

 00915 Calcium, dissolved mg/L 01012 Beryllium (total) μg/L 

 00916 Calcium, total mg/L 01020 Boron (dissolved) μg/L 

 00925 Magnesium, dissolved mg/L 01022 Boron (total) μg/L 

 00927 Magnesium, total mg/L 01025 Cadmium (dissolved) μg/L 

 00930 Sodium, dissolved mg/L 01027 Cadmium (total) μg/L 

 00929 Sodium, total mg/L 01030 Chromium (dissolved) μg/L 

 00935 Potassium, dissolved mg/L 01034 Chromium (total) μg/L 

 00937 Potassium, total mg/L 01035 Cobalt (dissolved) μg/L 

 00410 Alkalinity, total mg/L 01037 Cobalt (total) μg/L 

 00945 Sulfate mg/L 01040 Copper (dissolved) μg/L 

 00940 Chloride mg/L 01042 Copper (total) μg/L 

 00950 Fluoride mg/L 01046 Iron (dissolved) μg/L 

 01140 Silicon, dissolved mg/L 01045 Iron (total) μg/L 

 01142 Silicon, total mg/L 01049 Lead (dissolved) μg/L 

 01051 Lead (total) μg/L 

 NUTRIENTS 01056 Manganese (dissolved) μg/L 

 01055 Manganese (total) μg/L 

 00680 Total organic carbon mg/L 01060 Molybdenum (dissolved) μg/L 

 00610 Ammonia (as N) mg/L 01062 Molybdenum (total) μg/L 

 00630 Nitrate/Nitrite (as N) mg/L 01065 Nickel (dissolved) μg/L 

 00613 Nitrite mg/L 01067 Nickel (total) μg/L 

 00665 Phosphorus, total mg/L 01145 Selenium (dissolved) μg/L 

 01147 Selenium (total) μg/L 

 BACTERIOLOGICAL 01075 Silver (dissolved) μg/L 

 01077 Silver (total) μg/L 

 -- E. coli -- 01057 Thallium (dissolved) μg/L 

 -- Total coliform -- 01059 Thallium (total) μg/L 

 01150 Titanium (dissolved) μg/L 

 01152 Titanium (total) μg/L 

 01085 Vanadium (dissolved) μg/L 

 01087 Vanadium (total) μg/L 

 01090 Zinc (dissolved) μg/L 

 01092 Zinc (total) μg/L 

--------------------------------------------------------------------------------------------------------------------
DATA COLLECTION AND METHODS 29

in the equation could be expressed in terms of 

additional variables; for example, as described in the 

“Watershed Characterization Using the PrecipitationRunoff Modeling System” section, there are several 

components to streamflow and Q could be expressed 

as the sum of overland flow, interflow, and base 

flow. 

It is convenient to describe water balances in 

terms of depth, in inches, over the area of consideration, and this is the convention that will be used in 

discussion of modeling results in this report. For 

example, 0.75 inch of precipitation for the watershed 

indicates a layer of water 0.75 inch deep over the 

entire watershed. The watershed area associated with 

reported depths (47.2 mi2 or 30,208 acres) is required 

to convert to the volume of acre-feet (1,888).

General Characteristics of the Precipitation-Runoff 

Modeling System

The distributed nature of PRMS allows evaluation of hydrologic processes at watershed and intrawatershed scales. The ability to model intrawatershed 

areas allows users to derive estimates of hydrologic 

conditions for areas defined on the basis of watershed 

knowledge. Typically, users define units within the

Table 10. Miscellaneous data collected in water year 2001, including analysis results for bromide, selected inorganic ions, 

wastewater compounds, and tritium

[--, no data; <, less than; >, greater than; tritium, in tritium units; bromide, chloride, fluoride, and nitrite plus nitrate as nitrogen, in milligrams per liter; chloride/bromide ratio, dimensionless; MRL, method reporting limit; estimated wastewater detections are values between the instrument detection level under 

ideal conditions and the method reporting limit; blanks, quality assurance samples]

Local

site

Identifier

Date

(month/

day/year)

Bromide Chloride Fluoride

Nitrite

plus

nitrate

Chloride/

bromide

ratio

Wastewatercompound

detections

above MRL

Estimated

wastewatercompound

detections

Tritium

sample date

(month/year)

Tritium

(in tritium

units)

GWA01 04/10/01 0.0232 1.29 0.4 0.69 56 -- -- 11/00 14.3

GWA02 04/10/01 0.0356 3.38 3.14 1.22 95 -- -- 11/00 6.2

GWB01 04/10/01 -- 165 <0.2 10.3 -- -- -- 11/00 17.1

GWB02 04/10/01 0.0271 3.16 1.12 <0.05 117 0 0 11/00 4.6

GWB03 04/12/01 <0.01 1.15 <0.2 0.13 >115 -- -- 11/00 12.2

GWC02 04/09/01 0.062 39 0.38 9.91 629 0 0 11/00 19.5

GWD04 04/12/01 0.0252 3.57 0.23 1.69 142 -- -- 11/00 14.5

GWF10 04/10/01 0.0346 6.02 1.29 0.11 174 -- -- 11/00 15.9

GWF11 04/10/01 0.0435 9.03 2.26 0.57 208 -- -- 11/00 8.3

GWF15 04/10/01 0.0112 14.4 0.25 0.23 1286 -- -- 11/00 13.1

GWG01 04/10/01 0.0156 0.74 1.13 <0.05 47 -- -- 11/00 11.1

GWH01 04/09/01 0.1063 21.1 0.47 2.17 198 0 0 11/00 19.7

GWH03 04/09/01 0.0714 60.5 0.42 1.71 847 1 2 11/00 13.3

GWJ01 04/09/01 <0.01 1.41 <0.2 0.61 >141 -- -- 11/00 33.2

GWJ02 04/09/01 -- 1.38 0.26 0.57 -- -- -- 11/00 ruined cell

GWK04 04/09/01 0.0119 3.82 2.35 0.81 321 -- -- 11/00 13.7

GWM06 04/09/01 0.1367 134 <0.2 8.84 980 0 0 11/00 12

GWM07 04/10/01 0.3594 5.48 0.34 2.16 15 -- -- 11/00 20.6

GWN01 04/09/01 0.029 5.38 1.58 0.28 186 -- -- 11/00 8.9

GWO02 04/09/01 0.169 62.2 1.92 <0.05 368 -- -- 11/00 2.3

GWO10 04/10/01 0.0314 111 <0.2 6.53 3535 0 0 11/00 12.3

GWO12 04/09/01 0.1058 102 <0.2 3.41 964 -- -- 11/00 12

GWP04 04/10/01 0.0305 4.77 0.22 1.45 156 0 0 11/00 18.9

GWP05 04/10/01 0.0611 55.6 0.33 3.06 910 0 5 11/00 22.2

SWD01 04/09/01 -- 119 <0.2 0.98 -- 0 1 11/00 --

SWE01 04/10/01 0.0348 68.6 0.28 0.33 1971 0 1 11/00 --

SWH01 04/09/01 0.0837 31.9 0.29 0.15 381 0 0 11/00 --

SWH01 04/09/01 0.1031 32 0.28 0.16 310 blank blank 11/00 --

SWL01 04/09/01 0.3131 138 0.21 <0.05 441 1 2 11/00 --
30 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

watershed that have a unique set of physical characteristics that dictate hydrologic response. In this report, the 

finest unit of delineation will be referred to, individually, as a “hydrologic response unit (HRU).” Each 

HRU supplies water to the subsurface in the form of 

downward-percolating soil-water excess, which is 

referred to as “I” in the evapotranspiration discussions. 

The soil-water excess is routed to interflow and baseflow reservoirs that are the source for interflow and base 

flow. Together, interflow and base flow account for 

ground-water contributions to streamflow. Interflow is 

relatively dynamic and occurs in direct response to 

precipitation, whereas base flow is relatively steady and 

may sustain streamflow through rainless periods.

In general, surface or near-surface processes 

such as interception, snowpack accounting, overland 

flow, infiltration, and evapotranspiration take place 

at the HRU scale, and interflow and base-flow 

accounting takes place at their respective subsurface 

reservoir scales. In this study, HRU’s were defined 

on the basis of slope and aspect by using automated 

procedures developed by the USGS (Viger and others, 

1998; Viger, 1998). Interflow and base-flow reservoirs 

are interlinked and can be referred to collectively as 

subsurface reservoirs. The subsurface reservoirs represent ground water that is associated with streamflow, 

which is a portion of all the ground water in the watershed. In the watershed characterization developed in 

this study, the subsurface reservoirs have a one-to-one 

relation with each other and were defined on the basis 

of geology and streamflow measurements. In this 

study, the subsurface reservoirs do not have a oneto-one relation with HRU’s, and there are typically 

several HRU’s associated with each interflow and 

base-flow reservoir. The methods and rationale used 

for schematization of HRU’s and interflow and baseflow reservoirs in the Turkey Creek watershed are 

discussed in the “Runoff Modeling” section.

The physically based nature of PRMS allows 

simulation of physical processes involved in watershed 

runoff. Processes are represented with algorithms that 

describe known physical laws or empirical relationships that have some physical interpretation based on 

measurable watershed characteristics. The individual 

terms in algorithms that require input from model 

users can be referred to as “input parameters.” For 

simulation of the Turkey Creek watershed, values 

for many input parameters, especially those that are 

related to physical characteristics of the basin, were 

estimated using parameterization routines described 

by Leavesley and others (1983) and Wolock (1997) 

that are implemented by Viger and others (1998).

Watershed Characterization Using the 

Precipitation-Runoff Modeling System

A brief introduction to PRMS watershed 

characterization is included here in order to provide 

readers with information about the nature of PRMS 

and to establish a context for terminology used in 

later discussions of runoff modeling. Readers in 

need of a more rigorous description of the intricacies 

of PRMS are referred to in Leavesley and others 

(1983).

The general schematization shown in 

figure 13 indicates many physical processes in a 

watershed that are characterized by PRMS. There 

are literally hundreds of PRMS system variables associated with the PRMS characterization of watershed 

processes, and figure 13 is a simplified yet effective 

schematization of the general watershed system that 

PRMS emulates. PRMS system variables that describe 

physical conditions such as soil moisture, ground 

water associated with streamflow, components of 

streamflow, and many other watershed conditions 

are sometimes referred to as “state variables” because 

they indicate status of various watershed conditions. 

In this report, PRMS simulations result in values for 

state variables on a daily basis.

The general schematization in figure 13 also 

indicates the way system inputs are used in model 

algorithms to determine system outputs. The figure 

depicts subsurface reservoirs for interflow and baseflow processes; these reservoirs are defined for 

accounting purposes. Readers should be careful not to 

assume that there are rigidly designed reservoirs in the 

subsurface of the watershed. Rather, there are certain 

subsurface processes, such as interflow and base flow, 

that are conceptualized and accounted for differently; 

the so-called reservoirs are designated to facilitate the 

associated accounting.

System inputs consist of daily precipitation, 

which describes the amount of water put into the 

system, and daily temperature extremes, which are 

used to define energy terms. System outputs consist of 

values for all state variables. Some of the most important state variables for this study are the three components of streamflow (overland flow, interflow, and base 

flow), evapotranspiration, and the contents of the 

subsurface reservoirs.

An additional state variable referred to as 

“GSNK” (ground-water sink) also is important to 

results presented in this report. GSNK is the amount 

of water that is removed from the base-flow reservoir
DATA COLLECTION AND METHODS 31

and cannot drain, by gravity, to local streams in the 

watershed. Conceptually, this water may be associated 

with underflow, which is ground water that leaves the 

watershed by means other than streamflow or evapotranspiration, or long-term storage.

In this report, the terms of greatest interest are 

those associated with inputs and outputs to the groundwater system. By using the framework of physical 

processes described above, an equation that describes 

ground water associated with base flow can be developed as follows:

(3)

where

BFR is change in the contents of the base-flow 

reservoir,

GWI is ground-water recharge to the base-flow 

reservoir,

BF is base flow, and

 GSNK is ground water that is lost from the baseflow reservoir.

∆BFR GWI BF = – – GSNK

∆

INPUTS

Air temperature

Evaporation

Sublimation Interception

Snowpack

Interflow

reservoir

Snowmelt

Impervious-zone

reservoir

Precipitation

Recharge zone

Lower zone

Soil-water

excess

Ground-water

recharge

Interflow

and base flow

reservoir

accounting

Soil-zone

reservoir

Throughfall

Sublimation

Transpiration

Base-flow reservoir

Ground-water sink

Transpiration

Evaporation

Evapotranspiration

Evaporation

Overland

flow

Overland

flow

Ground-water

recharge

Ground-water

recharge

Interflow

Base flow

Streamflow

Hydrologic

Response Unit

Accounting

Figure 13. Schematic diagram of selected physical processes characterized by Precipitation-Runoff Modeling 

System.
32 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

A similar equation can be used for interflow. The 

terms in equation 3 will be discussed in more detail 

in the “Runoff Modeling” section.

HYDROLOGIC CONDITIONS

Hydrologic conditions in the watershed 

are characterized on the basis of contemporary 

data collected as part of this study; contemporary 

conditions are compared to historical conditions when 

possible. The hydrologic conditions described in this 

section include evapotranspiration and surface- and 

ground-water conditions including water quality. 

Descriptions of evapotranspiration in the watershed 

are developed on the basis of sophisticated techniques 

described in the Appendix. Evapotranspiration 

measurements reduce the need to use less accurate 

estimates of evapotranspiration when developing 

water balances.

Evapotranspiration

ET results and analyses are presented in terms 

of calendar year (January 1 to December 31) rather than 

water year (October 1 to September 30) for two reasons. 

First, the annual cycle of ET tends to be in phase with the 

calendar year, peaking near midsummer and reaching a 

minimum near midwinter. Therefore, the bulk of the flux 

occurs near the middle of the year and divisions between 

years occur at times of low flux. Second, because data 

collection began in early 1999, the use of calendar years 

provides three full years of data (including the estimate 

of ET for January 1999), whereas only two full water 

years of data were collected. The calendar-year summaries presented in this section related to ET should not 

be used in conjunction with water-year summaries 

presented elsewhere in this report.

Forest Site Results

Daily totals of ET at the forest site are shown 

for all 3 years in figure 14. Daily totals of precipitation 

and daily means of soil moisture are shown in figure 15. 

Soil moisture is computed as the mean of soil moisture 

measurements made at 0.16-ft and 0.75-ft depths 

(table 4). Daily means of solar radiation are shown 

in figure 16.

Evaporation of water requires both energy and 

water availability. A general pattern of greater ET

values from midspring to the end of summer and smaller 

values the rest of the year can be seen during all 3 years 

(fig. 14). The overall pattern is somewhat similar to the 

annual trend in solar radiation (fig. 16). Solar radiation is 

the ultimate source of virtually all energy used for ET, 

and this general similarity illustrates the control of solar 

radiation on ET. A rather smooth sinusoidal curve can be 

imagined that passes through all the greatest values of 

solar radiation in figure 16, corresponding to clear-sky 

conditions. The clear-sky value changes by a factor of 

about 3.8 during the course of a year, caused by the tilt of 

the Earth’s axis. This seasonal variation in the maximum 

amount of energy available at the Earth’s surface is one 

of the main drivers of seasonal changes in ET. In addition, the effect of extremely overcast days on ET can be 

seen by noting numerous 1- to 3-day periods when solar 

radiation is very small (say, less than one-third of the 

clear-sky value) and corresponding decreases in ET

are evident.

In the context of ET, water availability refers to the 

presence of liquid or solid water near the Earth’s surface 

in locations where it can readily evaporate or sublimate 

into the atmosphere. At the forest site, available water 

is delivered as precipitation (rain or snow) or dew and 

resides as soil moisture, snowpack, or interception. 

Soil moisture is the water held in the spaces between 

soil particles and can contribute to transpiration or 

evaporation. Snowpack accumulates on the land surface 

during the winter and evaporates or sublimates slowly 

during that time. Interception is precipitation or dewfall 

that lodges in the vegetation canopy and evaporates or 

sublimates directly without reaching the land surface.

The influence of soil moisture on ET can be 

seen by comparing figures 14 and 15. Soil moisture 

increases immediately following large rainfall as the 

water soaks into the soil and then decreases slowly 

and asymptotically as the soil dries (fig. 15). The variability in soil moisture is reflected in the time series 

of ET as a modulation of the annual pattern set by 

solar radiation. Typically, this modulation occurs 

on a time scale of one to several weeks. For example, 

periods of high soil moisture and ET occurred during 

DOY’s 169–180 and 219–230 in 1999, and DOY’s 

179–186 and 230–258 in 2000. Conversely, dry soils 

reduced ET rates during DOY’s 160–167 and 223–229 

in 2000 even though solar radiation was near normal 

(fig. 16B). 
HYDROLOGIC CONDITIONS 33

0

0.1

0.2

Note: Evapotranspiration estimated before day of year 35

0

0.1

0.2

DAY OF YEAR

0

0.1

0.2

EVAPOTRANSPIRATION, IN INCHES PER DAY EVAPOTRANSPIRATION, IN INCHES PER DAY EVAPOTRANSPIRATION, IN INCHES PER DAY

0 30 60 90 120 150 180 210 240 270 300 330 360

A

B

C

Figure 14. Daily evapotranspiration at forest site during (A) 1999, 

(B) 2000, and (C) 2001.
34 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

Soil moisture also affects ET on a seasonal time 

scale. In a forest setting, soil moisture has a greater 

influence on transpiration than on evaporation from 

the soil surface. In general, soil moisture is greater 

during spring, summer, and early fall than during 

late fall and winter. Sap-flow measurements indicated 

that the lodgepole transpiration season lasted from 

about DOY 99 (April 8) to DOY 286 (October 12) 

in 2000, and from DOY108 (April 18) to DOY 271 

(September 28) in 2001. The correspondence of the 

greater soil-moisture levels with the transpiration 

season of the trees exerts a seasonal influence on ET

through water availability. This influence accentuates 

the seasonal control of solar radiation on ET. Whereas 

mean solar radiation varies seasonally by a factor of 

about 3.5 (fig. 16), mean ET varies seasonally by a 

factor of about 10 (fig. 14) as a result of the additional 

soil-moisture influence.

The influence of rainfall interception on ET can 

be seen by comparing figures 14 and 15. This relation 

is relatively subtle because the rainfall interception 

capacity of the forest is probably 0.1 to 0.2 inch (Rutter 

and others, 1975; Calder, 1977); however, single days 

of relatively high ET often occur on or immediately 

following days of rainfall. Interception increases ET

because the water is directly exposed to the passing air 

and to solar radiation. Examples of high ET days associated with rainfall are DOY’s 148, 244, and 264 in 1999, 

DOY’s 115, 130, and 200 in 2000, and DOY’s 113, 

165, and 206 in 2001. Interception also was responsible 

for many other days of high ET during the study. The 

timing of interception relative to solar radiation also 

strongly influences ET. Rain that falls at night, followed 

by a clear day, produces the greatest values of ET, 

whereas little ET may occur during several rainy days 

in a row because the evaporation process during the 

rainy period is energy limited.

The influence of snowfall interception on ET

is somewhat more apparent than rainfall interception, 

because the snowfall interception capacity is greater 

than that for rain. Snow interception capacity is probably about 4 inches of snow (Lundberg, 1993), which 

is equivalent to 0.4 inch of water at a water density of 

10 percent. If the snow remains in the tree canopy, it 

can boost ET noticeably for several days after a snowfall. For example, high ET rates associated with snowfalls occurred on DOY’s 327–330 and 338–344 in 1999, 

DOY’s 2–4 and 28–33 in 2000, and DOY’s 17–20 and 

40–47 in 2001. These events maintained elevated ET

rates for 3 to 8 days following snowfall. Often, however, 

the snow unloads from the canopy to the ground before 

it fully evaporates or sublimates. This can be caused by 

high wind, temperature, solar radiation, or a combination of these factors. Examples of short-term elevated

ET following snowfall occurred on DOY’s 64 and 356 

in 1999, DOY’s 63, 81, and 342 in 2000, and DOY’s 29 

and 323 in 2001.

0

1

2

PRECIPITATION,

IN INCHES PER DAY

10

20

30

40

SOIL MOISTURE, IN PERCENT

PRECIPITATION,

IN INCHES PER DAY SOIL MOISTURE, IN PERCENT

PRECIPITATION,

IN INCHES PER DAY SOIL MOISTURE, IN PERCENT

Note: Soil moisture estimated before day of year 150 

0

1

2

10

20

30

40

DAY OF YEAR

0

0 30 60 90 120 150 180 210 240 270 300 330 360

1

2

10

20

30

40

A

B

C

Figure 15. Daily precipitation and daily mean soil moisture 

at forest site during (A) 1999, (B) 2000, and (C) 2001.
HYDROLOGIC CONDITIONS 35

0

50

100

150

200

250

300

350

400

SOLAR RADIATION, IN WATTS PER SQUARE METER

0

50

100

150

200

250

300

350

400

SOLAR RADIATION, IN WATTS PER SQUARE METER

0

0 30 60 90 120 150 180 210 240 270 300 330 360

50

100

150

200

250

300

350

400

SOLAR RADIATION, IN WATTS PER SQUARE METER

DAY OF YEAR

A

B

C

Figure 16. Daily mean solar radiation at forest site during (A) 1999, 

(B) 2000, and (C) 2001.
36 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

Using data collected during this study, a water 

balance was computed for the vegetated surface at the 

forest site. A layer was established, extending from 

just above the plant canopy to just below the root zone. 

Accounting for all inputs, outputs, and changes in 

storage in the layer during some time period, the 

balance can be written as:

(4)

where 

P is precipitation,

ET is evapotranspiration,

I is soil-water excess that percolates downward 

and is referred to as infiltration in ET

discussions in this report,

O is overland flow,

∆C is change in canopy storage,

∆SP is change in snowpack storage, and

∆SM is change in soil moisture storage.

I is the amount of water that infiltrates out of 

the bottom of the layer, below the root zone. This is the 

water that has the potential to become recharge to the 

ground-water system. O is water that moves as sheetflow over the land surface into a stream during and after 

precipitation. Because of the relatively permeable sandy 

soils, the organic litter mat on the forest floor, the gentle 

slope, and the low rainfall intensities at this site, it is 

estimated that overland flow was negligible at this site 

during the study period (O = 0). ∆C is the change in 

the amount of water stored in the vegetation canopy 

(either liquid or solid) during the time period. ∆SP is 

the change in the amount of water stored in the snowpack on the land surface during the time period. Annual 

values of ∆C and ∆SP were calculated using observations of canopy and snowpack storage made during 

site visits on December 30, 1998, December 23, 1999, 

January 3, 2001, and January 2, 2002. Observations 

of storage on these dates were adjusted by measured

ET and P between these dates and the end of the year 

(midnight, December 31) to obtain year-end values. 

Canopy storage (and therefore ∆C) at year end was 

zero for all 4 years. Snowpack storage was calculated 

by multiplying an estimated snow depth by an estimated 

water density in the snowpack, and ∆SP was computed 

by difference. Year-end values of soil-moisture storage 

were computed by multiplying soil moisture measured 

at midnight on December 31 (mean of –0.16 ft and 

–0.75 ft readings, table 4) by a rooting depth. Based 

on observations of uprooted lodgepole trees near the 

tower, the rooting depth is estimated to be 2 ft. The 

rooting depth may be underestimated because uprooted 

(toppled) trees tend to leave the smaller, deeper roots 

in the ground and only the larger, shallower roots are 

observable in the toppled tree-root mass. Using a 

deeper rooting depth was considered unjustifiable, 

however, because the deepest soil-moisture sensor 

was located at a depth of 0.75 ft. Annual values of 

∆SM were computed by difference. Equation 4 was 

then used to solve for annual values of I. Annual values 

of all terms in equation 4 are presented in table 11.

P ET – – I – O = ∆C + + ∆SP ∆SM

Table 11. Climatic and water balance summary for calendar years 1999, 2000, 2001, and 3-year mean, at forest site

[--, not applicable; *, value estimated using partial-year data, adjusted using a ratio determined from 2000 and 2001 data; infiltration calculated using 

equation 4]

Term 1999 2000 2001 3-year mean

Percentage of 

3-year mean

precipitation

Precipitation (inches) 26.43 18.17 19.20 21.27 100

Evapotranspiration (inches) 18.73 17.34 16.83 17.63 82.9

Change in canopy storage (inches) 0.00 0.00 0.00 0.00 0.0

Change in snowpack storage (inches) 0.55 –0.74 –0.30 –0.16 –0.8

Change in soil moisture storage (inches) 0.00 –0.23 –0.11 –0.11 –0.5

Infiltration (inches) 7.15 1.80 2.78 3.91 18.4

Mean air temperature (°F) 43.82 43.69 43.76 43.76 --

Mean soil moisture (percent) 9.35 8.31 8.76 8.81 --

Mean solar radiation (watts per square meter) 194.0* 185.1 180.3 186.5 --
HYDROLOGIC CONDITIONS 37

Precipitation, P, was much more variable than ET

during the 3 years of study (table 11). Annual P varied 

by 8.26 inches and annual ET varied by 1.90 inches: a 

ratio of 4.3 to 1. At a site with a deep water table, where

ET from ground water cannot occur, a positive correlation between ET and P would be expected because the 

water needed for ET to occur is derived primarily from 

P (eq. 4, table 11). At this site, ET tended to reflect the 

annual value of P (r = 0.93; however, with only three 

data points, r has little significance), but not consistently. A comparison of 2000 and 2001 shows that ET

was less in 2001 even though P and mean soil moisture 

(table 11) were greater. Because energy also is needed 

for ET, the smaller ET value in 2001 probably was 

caused by the smaller value of solar radiation that year 

(table 11). Air temperature appears not to be a factor in 

the 2000–2001 ET comparison (table 11). Overall, ET

was 82.9 percent of P during the 3 years of study at this 

site.

Infiltration, I, was quite variable during the 

3 years of study (table 11). I decreased from 7.15 inches 

in 1999, a wet year, to 1.80 inches in 2000, a dry year. 

This large contrast (a ratio of 4 to 1) was caused primarily by the large percentage of P that is removed by

ET, combined with the relatively constant nature of ET

from year to year. I can be thought of as an upper limit 

on the amount of water that reaches the water table 

(recharge) beneath the forest site. Although this water 

infiltrates below the root zone, some of it may resurface 

as spring discharge, for example, at the site of temporary perched water tables, considering the complex 

structure of the weathered granite regolith underlying 

the site. The 3 years of study illustrate quite well that 

at a semiarid upland site, the water potentially available 

for recharge is small and quite sensitive to the variability in P from year to year. Overall, I was 18.4 

percent of P during the 3 years of study at this site.

A rough estimate of long-term mean infiltration 

at the forest site can be made by relating I to P. Annual 

values of I and P are plotted in figure 17. The three 

points are nearly collinear (r2 = 0.997), indicating that 

at this site, annual I might be predicted somewhat reliably as a function of annual P. The best fit line shown 

in figure 17 is described by the equation:

(5)

where I is infiltration and P is precipitation, both in 

inches per year. The mean P for 1951–80 at this site 

is estimated to be 19.0 inches based on data from the 

Colorado Climate Center (1984). Inserting this estimate of long-term P into equation 5 yields an estimate 

of 2.47 inches (13.0 percent of P) of long-term mean 

infiltration at this site. Although the three points in 

figure 17 are nearly collinear, they constitute a very 

small data set. Therefore, equation 5 should be used 

only as a guideline because other years may plot 

farther from the line. Probably the greatest source of 

variability in the relation between I and P is the timing 

of P. In general, fewer and larger precipitation events 

(especially events that occur in the spring or fall) 

produce more I than the same amount of precipitation 

spread out over a greater number of small events. 

Overwhelming the root zone with water from large 

events causes infiltration below the root zone by 

gravity flow, whereas smaller, more frequent additions 

of water can be absorbed by the soil and held in place, 

ultimately to be discharged as ET. 

Equation 5 also can be used to estimate the 

effects of very dry years on infiltration. As seen in 

figure 17, the equation predicts zero I at an annual P of 

about 15 inches. Use of equation 5 in this way is even 

more tentative than for predicting long-term mean I 

because in addition to the variability mentioned previously, factors related to extrapolation arise. Beyond 

the range of P measured in this study, the relation 

between I and P is completely untested. For example, 

as P decreases below about 17 inches, I may plot 

above the projected line, asymptotically approaching 

zero as P approaches zero (dotted line in figure 17). 

However, figure 17 indicates that during very dry 

years when P is 15 inches or less, I is likely to be 

very small, probably less than 1 inch, at this site.

Equation 4 also was used to calculate I on a 

daily basis. The daily values were summed to calculate 

a cumulative value, ΣI, during the course of a year, in 

order to learn more about the timing of I (fig. 18). To 

accomplish this, an assumption was made about ∆C

and ∆SP because these were not measured on a daily 

basis. Daily values of both terms were set equal to the 

annual values divided by the number of days in the 

year. This treatment introduces transient errors in the 

time series of ΣI, but these errors cancel by the end 

of the year. For example, a 10-inch snowfall with a 

water density of 10 percent will cause an immediate 

apparent increase in ΣI of 1 inch of water (assuming 

that ET, O, and ∆SM all equal 0); however, during the 

following days, as the snow evaporates, sublimates, 

or melts, the value of ΣI gradually decreases to a more 

realistic value. This process creates a sawtooth pattern 

in the wintertime series of ΣI characterized by a steep

I = 0.633P – 9.55
38 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

increase followed by a slower, asymptotic decrease. 

Daily values of ∆SM were calculated using midnight 

measurements of soil moisture (table 4), multiplied by 

a rooting depth. The two soil-moisture sensors were 

located under the edge of a tree crown and may not 

be a good indication of the site-mean soil moisture at 

all times (Nnyamah and Black, 1977), although their 

long-term values probably are indicative of the site 

mean. In addition, the rooting depth, as noted above, 

may be underestimated. The effect of these two potential sampling errors is similar to that of ∆C and ∆SM

on the calculation of ΣI, causing a sawtooth pattern 

during the warmer months. Finally, SM was estimated 

during early 1999 (fig. 15A), which introduces further 

sawtooth artifacts but again has very little effect on 

the final value of ΣI (winter soil moisture typically 

is low and relatively constant; see fig. 15). The 

sawtooth artifacts in figure 18 largely can be removed 

by computing a 30-day running mean of ΣI, shown 

as a dotted line in figure 18. Use of the running mean, 

however, does not remove the longer term storage 

artifacts and probably underestimates the rapidity of 

the infiltration events. As a result of storage artifacts, 

only the larger changes in ΣI (fig. 18) are meaningful. 

In particular, gradual decreases in ΣI (implying 

upward movement of water into the root zone) for 

extended periods primarily are caused by measurement errors in ∆SM and represent periods of little 

or no infiltration.

The 30-day running mean of ΣI during 1999 

reveals that I tends to be episodic, occurring primarily 

in the spring and secondarily in the fall (fig. 18A). 

The largest single I event occurred between about 

DOY’s 103 and 145 of 1999. During this period, 

10.4 inches of P fell, mostly in four large multiday 

events (fig. 15A), and about 6 inches of I occurred. 

Transpiration probably began for the year during this 

period (it began on DOY 99 in 2000 and DOY 108 in 

2001) but remained at a low level during most of the 

period (fig. 14A). This sequence indicates that I occurs 

most effectively when storms are large and closely 

spaced in time and ET is small. These conditions all 

contribute to exceeding the water-holding capacity of 

the root zone and to causing I. Because ET depletes the 

root-zone soil moisture between storms, low ET rates 

and short periods between storms maintain high soilmoisture levels, reducing the amount of additional 

storage available. A steady rainfall for several days is 

particularly effective at causing I because root-zone 

storage is maintained virtually full, routing all new P

directly to I. Events of about 2 inches of water separated by only a few days seem to be sufficient to cause 

substantial springtime I at this site. During the summer 

of 1999, two large rainfall events totaling 4.0 inches 

occurred in quick succession (about DOY’s 210–222; 

fig. 15A) but caused little I (fig. 18A). ET levels were 

high between days of rainfall during this period and 

tended to keep the root zone relatively dry between the

15 20 25 30

PRECIPITATION, IN INCHES PER YEAR

0

1

2

3

4

5

6

7

8

9

10

INFILTRATION, IN INCHES PER YEAR

2000

2001

1999

Best fit line

Possible extrapolation

 at low values of

 precipitation

Measured

Figure 17. Annual precipitation and infiltration at forest site during the 

study period.
HYDROLOGIC CONDITIONS 39

–1

0

1

2

3

4

5

6

7

8

PRECIPITATION AND CUMULATIVE INFILTRATION, IN INCHES –1

0

1

2

3

4

5

6

7

8

PRECIPITATION AND CUMULATIVE INFILTRATION, IN INCHES –1

0

1

2

3

4

5

6

7

8

PRECIPITATION AND CUMULATIVE INFILTRATION, IN INCHES

Precipitation

Cumulative infiltration

30-day running mean

.

0 150 180 210 240 270 300 330 360 30 60 90 120

DAY OF YEAR

EXPLANATION A

B

C

Figure 18. Daily precipitation and cumulative infiltration at forest site during (A) 1999, (B) 2000, 

and (C) 2001.
40 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

events. Only very large, successive rainfalls during the 

summer are likely to cause substantial I. In the fall of 

1999, three early snowfalls that subsequently melted 

(DOY’s 325–338; figure 15A) were sufficient to cause 

a significant amount of I. Even though these snowfalls 

totaled only 2.2 inches of water, I occurred primarily 

because transpiration had long since ceased for the 

year.

The large springtime pulse of I that occurred 

during 1999 at the forest site is not nearly as evident 

during 2000 or 2001. The dry spring of 2000 was 

notably lacking in P, and the storms generally lasted 

only 1 or 2 days (fig. 15B). The conditions needed to 

exceed the water-holding capacity of the root zone 

were seldom met, and only about 1.3 inches of I 

occurred (fig.18B). Precipitation during the spring of 

2001 shared elements with both of the previous years. 

Three multiday springtime storms occurred in 2001 

(DOY’s 100–126) that were similar in timing and 

duration to those in 1999 but totaled only 5.3 inches 

(fig. 15C). The resulting 2.4 inches of I (fig. 18C) was 

greater than in 2000 but much less than the 1999 value. 

A small amount of I appears to have occurred in the 

fall of 2000 and 2001 (figs. 18B and 18C), but the 

apparent increases in ΣI may just be storage-term artifacts caused by the accumulation of snowpack during 

this time.

In summary, during the 3-year study period 

at the forest site, mean annual values of precipitation 

(P), evapotranspiration (ET), and infiltration (I) were 

21.27 inches, 17.63 inches, and 3.91 inches, respectively. ET was 82.9 percent of P, whereas I was only 

18.4 percent of P. ET was positively correlated with 

P but was much less variable. As a result, I was quite 

variable because I is largely determined by the difference between P and ET. The 3 years spanned a relatively wide range of water availability, from slightly 

drier than average to very wet. For the 3 years of study, 

I was very nearly a linear function of P. Long-term 

mean P at this site is estimated to be 19.0 inches, 

yielding a long-term mean estimate for I of about 

2.47 inches. A daily water balance revealed that I 

overwhelmingly occurs in the spring, when ET is still 

small. The amount of I depends on both the amount 

and timing of P. A few large storms occurring in quick 

succession effectively cause I, whereas many smaller 

events tend to be absorbed in the root zone and lost to

ET. I also occurred in the fall after transpiration had 

ceased for the year, but to a lesser degree than in the 

spring. Very little I occurred during the summer, even 

during relatively large storms. At these times, higher

ET rates apparently removed soil moisture at a sufficient rate that the root zone did not exceed its waterholding capacity.

Meadow Site and Comparison to Forest Site

Daily totals of ET at the meadow site and forest 

site are shown for 2000 and 2001 in figure 19. Daily 

totals of precipitation at the meadow site and daily 

means of soil moisture at the meadow and forest sites 

are shown in figure 20. Soil moisture was an integrated 

measurement over the 0- to 1-ft depth at the meadow 

site (table 5). Daily mean values of solar radiation are 

shown in figure 21.

Although a general similarity can be seen 

between the annual patterns of ET at the forest and 

meadow sites, significant differences also are apparent 

at various times of the year (fig. 19). The meadow soil 

was wetter than the forest soil year round, especially 

during the growing season (fig. 20), even though the 

two sites received equal P during the one full calendar 

year of comparison, 2001 (table 12). The meadow soil 

is finer grained than the forest soil and tends to hold 

more of the infiltrating water close to the surface. 

Therefore, water availability is less limiting at the 

meadow site, and ET depends more on the energy 

input. For example, the greatest ET values at the 

meadow site occurred during late spring (about 

DOY’s 151–169) in 2001 (fig. 19B). The pattern of

ET bears little resemblance to the pattern of soil moisture during this period, which decreased from about 

27 percent to about 17 percent (fig. 20B). However, 

the pattern of ET is very similar to the pattern of solar 

radiation (fig. 21B), which also was peaking during 

this period. Although soil moisture was decreasing 

rapidly, it was in ample supply and therefore ET

was energy limited. Further, soil moisture at this site 

peaked in early spring of 2001 (about DOY’s 91–151, 

fig. 20B) before the peak ET (about DOY’s 151–169). 

During the soil-moisture peak ET was well below its 

peak value (fig. 19B) and again was highly correlated 

with and limited by solar radiation (fig. 21B). Soil 

moisture was not always plentiful at the meadow site, 

however. The steady decrease in ET rates from about 

DOY’s 209–230 in 2000 is related to the severe drop 

in soil moisture during that time, not to the amount 

of solar radiation.
HYDROLOGIC CONDITIONS 41

0

0.05

0.10

0.15

0.20

0.25

EVAPOTRANSPIRATION, IN INCHES PER DAY

0

0.05

0.10

0.15

0.20

0.25

EVAPOTRANSPIRATION, IN INCHES PER DAY

Forest

Meadow

0 150 180 210 240 270 300 330 360 30 60 90 120

DAY OF YEAR

A EXPLANATION

B

Figure 19. Daily evapotranspiration at meadow and forest sites during (A) 2000 and (B) 2001.
42 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

0

1

2

PRECIPITATION, IN INCHES PER DAY

10

20

30

40

 SOIL MOISTURE, IN PERCENT

0

1

2

PRECIPITATION, IN INCHES PER DAY

10

20

30

40

 SOIL MOISTURE, IN PERCENT

Meadow

Forest

0 150 180 210 240 270 300 330 360 30 60 90 120

DAY OF YEAR

Meadow

Forest

A

B

Figure 20. Daily precipitation at meadow site, and daily mean soil moisture at meadow and 

forest sites during (A) 2000 and (B) 2001.
HYDROLOGIC CONDITIONS 43

0

50

100

150

200

250

300

350

400

SOLAR RADIATION, IN WATTS PER SQUARE METER

0

50

100

150

200

250

300

350

400

SOLAR RADIATION, IN WATTS PER SQUARE METER

0 150 180 210 240 270 300 330 360 30 60 90 120

DAY OF YEAR

A

B

Figure 21. Daily mean solar radiation at meadow site during (A) 2000 and (B) 2001.
44 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

During the growing seasons a number of shortterm differences in ET between the two sites occur 

(fig. 19). The largest differences occurred when 

meadow ET rates exceeded forest ET rates, as on 

DOY’s 155–167, 171–175, 181–191, and 246–263 

in 2000 (fig. 19A), and DOY’s 128–136, 142–148, 

151–163, 165–186, and 196–203 in 2001 (fig. 19B). 

Every one of these periods began shortly after a rainfall, corresponded to a drying trend in soil moisture 

(or dry-down) at both sites, and ended just before 

the beginning of another rainfall (figs. 15, 20). 

(Technically, the first period in 2000, represented 

by DOY’s 155–167, probably began on DOY 140 

[fig. 15B], but data collection at the meadow site 

began on DOY 155). In general, dry-downs with 

greater ratios of meadow to forest soil moisture were 

typified by greater ratios of meadow to forest ET. 

However, this proportion was not always preserved 

and probably was modified somewhat by phenological 

differences between the meadow grasses and the forest 

lodgepole pines. Nonetheless, this set of dry-downs 

clearly illustrates that ET at the forest site is more 

sensitive to soil moisture than is ET at the meadow 

site. Differences in interception also caused short-term 

contrasts in growing-season ET rates between the two 

sites. Because the forest interception capacity is much 

greater than that of the meadow, forest ET rates typically were greater than meadow ET rates during or 

one day after days of rainfall. If rainfall occurred 

over several days, forest ET rates generally exceeded 

meadow ET rates for the whole period. Forest ET rates 

exceeded meadow ET rates due to interception on 

DOY’s 178–180, 193–194, 217–219, and 230–236 in 

2000 (fig. 19A) and DOY’s 125–127 and 249–252 in 

2001 (fig. 19B). Most of the significant differences 

between forest and meadow growing-season ET rates 

during the study can be explained in terms of soilmoisture differences during dry-downs and differences 

in interception. The combination of these two influences tends to produce an alternating pattern during 

the growing season: greater ET at the forest during 

and just after rainfall, followed by greater ET at the 

meadow during the intervening dry-down (figs. 15, 

19, 20).

During the nongrowing season, the relative 

evaporation (or sublimation) rates at the meadow and 

forest depend mostly on the amount of snow stored in 

the forest canopy and the amount of snowpack at both 

sites. Snow (or rain) stored in the forest canopy is most 

available for evaporation, followed by snowpack in the 

meadow, followed by snowpack on the forest floor. 

However, the interplay between these three sources 

is complex. The potential for meadow snowpack to 

evaporate depends on the percentage of snowpack 

cover in the meadow and the amount of snow in the 

forest canopy around the meadow. The reason is that 

snow is highly reflective, so that net radiation over a 

complete snowpack in winter usually is very near zero. 

For evaporation to take place, dark surfaces are needed 

to absorb solar radiation and convert this energy into 

heat, which is then used for evaporation. If the snowpack in the meadow is patchy, the bare patches absorb 

the sunlight and transfer the energy to the nearby snow 

patches (small-scale advection). If the forest canopy 

surrounding the meadow is snow-free, the trees absorb 

the sunlight and the energy can be advected over the 

meadow for evaporation there (large-scale advection). 

Evaporation of snow (or rain) stored in a tree canopy is 

always high because even at maximum snow capacity, 

dark fronds are partially exposed and promote smallscale advection. Small-scale advection is much more 

efficient than large-scale advection and will dominate 

if the two are in competition. Therefore, if snow is 

stored in the forest canopy surrounding the meadow, 

evaporation of the canopy snow will take precedence 

over evaporation of a full meadow snowpack. If the 

meadow snowpack is patchy and snow is stored in 

the surrounding forest canopy, the two evaporation 

rates may be similar. A patchy meadow snowpack 

surrounded by a snow-free forest canopy evaporates 

quickly because both small- and large-scale advection 

take place. Snowpack on the forest floor evaporates 

slowly because the trees shade the snowpack. The heat 

generated by the dark canopy moves upward into the 

atmosphere more easily than downward, effectively 

insulating the snowpack from the energy source.

Table 12. Climatic and water balance summary for 

calendar year 2001 at meadow and forest sites

[Infiltration calculated using equation 4]

Site Meadow Forest

Precipitation (inches) 19.20 19.20

Evapotranspiration (inches) 20.56 16.83

Change in canopy storage (inches) 0.00 0.00

Change in snowpack storage (inches) 0.21 –0.30

Change in soil moisture storage (inches) –0.14 –0.11

Infiltration (inches) –1.43 2.78

Mean air temperature (°F) 41.95 43.76

Mean soil moisture (percent) 15.41 8.76

Mean solar radiation (watts per square 

meter)

176.38 180.3
HYDROLOGIC CONDITIONS 45

The principles outlined in the previous paragraph 

explain most of the relative trends in ET seen at the 

forest and meadow sites during the nongrowing season 

(fig. 19). ET rates during much of this time were 

roughly equal, resulting from (a) a patchy meadow 

snowpack combined with moderate forest canopy 

storage, (b) a very patchy (nearly bare) meadow snowpack combined with an empty forest canopy but snow 

on the forest floor, or (c) no snow present at either site. 

These three conditions correspond to high, medium, 

and low rates at both sites. Interspersed among these 

periods of general similarity are periods when the 

two rates differed significantly. Some periods are very 

short and some are longer, but all tend to occur in 

response to snowfalls. Virtually all snowfalls initially 

boost the forest ET above meadow ET for a day or two, 

while the canopy snow evaporates rapidly by smallscale advection, as on DOY’s 311–313, 317–318, 323, 

and 360–361 in 2000, and DOY’s 101–104, 312, 323, 

and 350 in 2001. If snowfalls are small, these short 

bursts of forest ET usually deplete the canopy storage 

and are followed by relatively greater meadow ET for 

a short time. In this case, the meadow snowpack evaporates by a combination of large- and small-scale advection, as on DOY 319 in 2000 and DOY’s 313–315, 

324–326, and 352 in 2001. For larger snowfalls, or 

snowfalls in quick succession, the course that the 

relative ET rates take after the first day or two of relatively high forest ET mostly depends on the fate of the 

snow in the forest canopy. If the snow remains in the 

canopy, forest ET tends to be greater than meadow ET. 

However, in this foothills setting, snow often unloads 

from the canopy and falls to the ground before evaporating, as a result of high winds, temperature, solar 

radiation, or a combination of these. In this case, forest

ET suddenly drops because the snow is shaded, the 

energy received by the forest is redirected to meadows 

by large-scale advection, and meadow ET rates can 

exceed forest ET rates. Two examples of snow 

remaining in the forest canopy for extended periods 

occurred on DOY’s 17–33 and DOY’s 40–54 in 2001. 

Forest ET was relatively high during these periods, 

and meadow ET was near zero. Examples of ET patterns 

resulting from large-scale advection occurred on 

DOY’s 325–339 in 2000, DOY 362 in 2000 to DOY 6 

in 2001, and DOY’s 360–362 in 2001. Meadow ET

significantly exceeded forest ET during these periods.

A water balance was computed for the meadow 

site 2001 calendar year using equation 4 and is 

compared to the forest site in table 12. I at the meadow 

site was –1.43 inches for the year, indicating a net 

movement of water upward into the root zone and then 

into the atmosphere at the meadow site. ET exceeded P

by 1.36 inches (table 12), which accounted for most 

of the upward movement. Differences in soil moisture 

probably account for the differences in ET between the 

meadow and forest sites. On average, soil moisture at 

the meadow site was 76 percent greater than soil moisture at the forest site (table 12), and during the growing 

season, it was often 100–200 percent greater (fig. 20). In 

contrast, mean values of solar radiation and temperature 

at the meadow were both lower than at the forest during 

2001 (table 12) and probably did not contribute to the 

greater ET rates. As mentioned previously, the meadow 

grass appeared to be not overly lush, except for the 

grasses in the riparian zone of an intermittent stream 

that runs roughly south to north near the east edge of the 

meadow. Because the meadow slopes at about 7° down 

to the stream, water-table depth is expected to be deeper 

to the west side of the meadow and shallower to the east, 

approaching land surface near the stream at times when 

the stream is flowing. The capillary fringe thickness in 

the fine-grained meadow soil probably is in the range of 

2–5 ft (Fetter, 1980, p. 80), creating a zone of water that 

is available for ET 2–5 ft above the water table. Therefore, water probably was amply supplied to the grass 

roots in a relatively large zone surrounding the stream. 

The ET station was roughly centered in the meadow. 

Bowen-ratio measurements are a weighted mean of ET

rates from a source area, at this site extending about 

400–500 ft upwind from the sensors. For easterly wind 

directions, the source area included the lush grasses in 

the riparian zone and parts of the meadow with shallow 

water-table depths. Conversely, for westerly wind directions, the source area included parts of the meadow 

with deeper water-table depths. An analysis of wind 

direction, windspeed, and ET indicated that 67 percent 

of the measured ET occurred during times of easterly 

winds (azimuth 345°–165°). Therefore, the mean ET

measured at this site was significantly influenced by the 

greater ET rates that occurred in the riparian zone and 

in the shallow water table parts of the meadow. This site 

was selected to represent average grassland conditions 

in the watershed, but the measurements probably reflect 

somewhat wetter than average conditions because of the 

prevailing easterly winds at the site. Although the ET

measurements indicate the site is a discharge area (ET

is greater than P), the upper part of this meadow likely 

contributes to recharge while the lower part, near the 

stream, is a discharge area.
46 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

In summary, ET at the meadow site was significantly greater than ET at the forest site during the 

1-year, 7-month period of comparative measurements. 

During one full calendar year (2001), meadow ET was 

22 percent greater than forest ET, even though precipitation at the two sites was equal. During the growing 

season, interception contributed to greater ET rates at 

the forest site for short periods of time after rainfall 

events. However, this effect was minor compared to 

the greater meadow ET during interstorm dry-downs, 

when soil moisture at the forest site became limiting. 

Wintertime evaporation at the two sites was roughly 

equal, tending to be greater at the forest when intercepted snow was held in the canopy and greater 

at the meadow when the forest canopy was snow-free. 

Average soil moisture at the meadow was 76 percent 

greater than at the forest and often was 100–200 

percent greater during the growing season. The greater 

soil moisture at the meadow resulted from the finer 

grained soil at that site and probably accounted for a 

large part of the difference in ET rates between the two 

sites. An intermittent stream and its associated lush 

riparian grasses, however, also affected the ET

measurements at the meadow site more strongly than 

was anticipated because of the prevailing wind direction. As a result, the ET rates measured at this site 

probably are somewhat greater than ET rates from 

typical upland grasslands in the watershed.

Surface-Water Conditions

Records of streamflow in Turkey Creek near the 

mouth of the watershed describe surface-water conditions for the entire watershed. Intrawatershed records 

of streamflow describe the spatial variations in 

watershed-scale surface-water conditions.

Watershed Conditions

Streamflow hydrographs for four stream gages 

in the Turkey Creek watershed indicate an annual 

cycle dominated by direct runoff in the spring, usually 

March through May or June (fig. 22). Direct runoff is 

runoff that occurs in direct response to precipitation or 

snowmelt or both. In many years, a second period of 

direct runoff caused by thunderstorms occurs in the 

summer months. Direct runoff consists of overland 

flow and interflow. Records indicate that the magnitude of spring runoff ranges from daily mean peaks of 

less than 50 ft3/s to more than 200 ft3/s; instantaneous 

flows can be greater than 1,000 ft3

/s. The peak daily 

mean streamflow that was measured during spring 

runoff in 1949 is 208 ft3/s, or about 4.5 ft3

/s/mi2

(table 13). 

Spring hydrographs in the Turkey Creek watershed are typically asymmetrical and have a strong 

positive skew (fewer days with high flows than low 

flows). Asymmetrical hydrographs can be characterized with the term “flashy,” indicating that streamflow 

quickly rises from low levels to peaks that are short 

lived and then recedes. The hydrographs have a rising 

limb that rises abruptly and linearly increases to a 

sharp peak and a falling limb that recedes more slowly 

than the rising limb and is curvilinear. As direct runoff 

attenuates, the hydrograph slope may become nearly 

flat, indicating a transition from interflow to base flow. 

The duration of spring runoff in Turkey Creek depends 

on the size of the snowpack and amount of spring 

precipitation. If the snowpack is widespread and more 

than a few inches thick, the spring runoff can easily 

persist for weeks. 

The Turkey Creek watershed also experiences 

direct runoff as a result of local convective thunderstorms. Thunderstorm hydrographs sometimes punctuate the spring runoff hydrograph, as in May–June 

of 1999, and thunderstorms sometimes occur after the 

spring runoff hydrograph has completed its recession, as 

in July–August of 1999 (fig. 22). In either case, thunderstorm hydrographs have the same distinctive asymmetrical shape as spring hydrographs; however, their 

duration is typically much shorter. Although the largest 

peaks do occur from thunderstorms, in general, thunderstorms result in daily mean peaks of tens of cubic feet 

per second, or a fraction of typical spring peaks. Direct 

runoff from individual storms in the Turkey Creek watershed rarely persists for more than a few days and often 

lasts only hours. 

As indicated previously, the principal components of direct runoff are overland flow and interflow. 

Interflow consists of water delivered to streams from 

the subsurface in direct response to precipitation or 

snowmelt or both. Intuitively, interflow is associated 

with the soil zone, where intergranular porosity is 

likely to establish hydraulic characteristics capable 

of supporting the rapid movement of water (Hewlett, 

1961). In this report, the soil zone includes the transition from soil to indurated crystalline rock. The transition from the soil zone to the underlying crystalline 

rock is sharp in some places. In other places, however, 

it is gradational and consists of a weathered section of
HYDROLOGIC CONDITIONS 47

rock that is loose, coarse, and generally believed to be 

comparable to or greater than the soil zone in thickness. The bedrock surface also is commonly the site of 

low-angle stress-relief fractures. The soil zone and 

transitional weathered-bedrock zone mantle the crystalline rock surface and have a configuration that is 

very similar to the watershed topography. Intergranular porosity exists in the soil and weathered bedrock 

zones, which are collectively referred to as “regolith” 

in this report. The differences between the intergranular porosity present in the soil and transition zones 

compared to the fracture porosity in the crystalline 

rock also provide a physical basis for definition of 

a preferential flow path along their interface.

In general, overland flow is a very quick and 

short-lived component of direct runoff. Interflow is 

usually a much larger component of the direct-runoff 

hydrograph than overland flow because most precipitation or snowmelt infiltrates into the subsurface 

(Hewlett, 1961). Because interflow emanates from the 

subsurface and moves through a porous medium rather 

than over the land surface, it moves more slowly than 

25

250

200

150

100

50

0

–50

250

200

150

100

50

0

–50

250

200

150

100

50

0

–50

20

15

10

5

1940

ANNUAL PRECIPITATION, 

IN INCHES

1960 1980 2000

DISCHARGE, IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND DISCHARGE, IN CUBIC FEET PER SECOND

Streamflow from stations 06710995 and 06710992

Streamflow from station 06711000

Cheesman site

Average

Streamflow from station 06711040

JFMAM

1998 1999 2000 2001

1998

1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953

1999 2000 2001

J J A S OND JFMA MJ J A S OND JFMA MJ J A S OND JFMA MJ J A S OND

JFMA MJ J A S OND JFMA MJ J A S OND JFMA MJ J A S OND JFMA MJ J A S OND

J JJ J JJ J JJ J JJ J JJ J JJ J JJ J JJ J JJ J JJ J JJ J JJ

Figure 22. Streamflow hydrographs for the three stream gages on Turkey Creek and annual precipitation at the 

Cheesman site.
48 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

overland flow. This difference in rate of movement is 

a principal contributor to the curvilinear nature of the 

recession typical of the falling limb for asymmetrical 

hydrographs.

Between periods of direct runoff, streamflow 

in the Turkey Creek watershed may be sustained at 

relatively steady and low levels of base flow that 

emanates from ground water. Streams that have 

sustained streamflow through relatively long rainless 

periods are referred to as “well sustained.” For wellsustained streams, base flows may vary seasonally but 

are typically steadier than variations in the components of direct runoff.

If streamflow is not sustained through relatively 

long rainless periods, streams become dry and are 

referred to as “poorly sustained” or “intermittent.” 

Streams may go dry because there is little groundwater recharge in their contributing drainage area or 

because any ground-water recharge that does occur 

is quickly transmitted to streamflow. The presence of 

base flow in streams indicates that local ground-water 

levels are high enough to support streamflow. The 

absence of base flow in the watershed does not indicate that all ground water has drained from the watershed; however, it does indicate that local ground-water 

levels are below the streambed.

About 65 days of zero flow, or about 5 percent 

of the period of record (April 1998 to April 2001), 

are reported for station 06710995 (table 13). During 

periods reported as zero streamflow in the summer of 

2000, the stream was observed to be flowing a short 

distance both upstream and downstream from the 

stream gage, indicating the presence of anomalous 

conditions with a low bias at the gage site. The anomalous conditions are most likely related to the proximity 

of a major geologic contact that acts as a local streamflow sink. Records from other Turkey Creek stream 

gages in the vicinity of the canyon mouth, representing 

16 years of measurements, indicate very few days of 

zero streamflow in the watershed (table 13). Compositing all streamflow records available for Turkey Creek 

in the vicinity of station 06710995 provides 6,506 days 

of streamflow record (table 13) that contains 86 days 

of zero streamflow, which is only about 1.3 percent of 

the composited record and only 21 days more than the 

number of days with zero streamflow in the relatively 

short record from 06710995.

Based on reported data, annual streamflow 

in Turkey Creek, reported as a depth of water over 

the entire watershed, ranges from as little as 0.39 inch 

to as much as 5.83 inches (table 14). Daily mean 

streamflow is rarely greater than 100 ft3/s (less 

than between 1 and 2 percent of the time; table 13); 

however, it is frequently less than about 1 ft3

/s 

(40 percent of all mean daily flows are less than 

0.92 ft3/s; table 13). 

Although the series of annual watershed streamflow values for Turkey Creek is incomplete, the series 

of annual precipitation data from Cheesman Reservoir 

(fig. 1) is complete for water years 1949 through 2001 

(table 14) and can be used to characterize climatic 

conditions for the past several decades in the vicinity 

of the Turkey Creek watershed. Precipitation records 

from Cheesman Reservoir, which have an annual wateryear average of 16.49 (table 14), are probably biased 

low compared to precipitation records from the Turkey 

Creek watershed, which have an estimated annual 

average of about 18 inches based on information 

compiled by the Colorado Climate Center (1984). At 

Cheesman Reservoir, for the 22-year period of water 

years 1980 through 2001, all but 7 years exceeded the 

1949 through 2001 annual mean precipitation, indicating that conditions have been relatively wet during 

the past two decades. However, the Cheesman precipitation data also include relatively dry years, many of 

which are in the 1950’s and 1960’s and, in general, 

describe a normally distributed series of data. The 

Cheesman data set covers 53 years and is a more robust 

representation of natural climatologic conditions for the 

area compared to the approximately 3-year set of 

contemporary data collected as part of this study.

Intrawatershed Conditions 

Intrawatershed surface-water conditions help 

describe spatial variability of hydrologic processes in 

the Turkey Creek watershed and are especially useful 

for characterizing base-flow conditions in the four 

rock groups as described in the “Interflow and BaseFlow Reservoir Delineation and Parameterization” 

section. The intrawatershed records of streamflow are 

sometimes referred to as “short-term records” because 

they were operated only from April 2001 through 

July 2001. Each intrawatershed record indicates the 

integrated effect of all hydrologic processes occurring 

within its contributing drainage area. The four shortterm records of streamflow (locations shown in 

fig. 23) were collected primarily to describe differences in base-flow rates in the watershed. Streamflow 

records, normalized for contributing drainage area 

(table 15), from the four sites are shown in figure 24 

and can be used to make observations concerning the 

variability of base-flow rates in the watershed.
HYDROLOGIC CONDITIONS 49

Table 13. Streamflow statistics for Turkey Creek

[Composite, all records of streamflow on Turkey Creek; Percent,

 percentage of time given streamflow, in cubic feet per second, 

 was equaled or exceeded]

 Univariate statistics

---------------------------------------------- 

 Days of

 Station Mean Minimum Maximum record

--------- ----- -------- ------- ------- 

06710992 5.54 0.11 41.00 171 

06710995 10.97 0.00 177.75 1109 

06711000 5.75 0.00 208.00 3971 

06711040 11.94 0.32 137.00 1255 

Composite 7.83 0.00 208.00 6506 

---------------------------------------------- 

 Duration statistics

-----------------------------------------------------------------

 Station and discharge

 --------------------------------------------------------

Percent 06710992 06710995 06711000 06711040 Composite 

------- --------- --------- --------- --------- ---------

 99. 0.13 0.00 0.09 0.34 0.01

 98. 0.15 0.00 0.09 0.41 0.08

 95. 0.20 0.01 0.19 0.68 0.19

 90. 0.25 0.14 0.24 0.90 0.26

 85. 0.32 0.42 0.28 1.09 0.33

 80. 0.42 0.60 0.33 1.26 0.39

 75. 0.56 0.77 0.37 1.44 0.49

 70. 0.70 0.94 0.42 1.66 0.63

 65. 0.84 1.14 0.51 1.91 0.78

 60. 0.99 1.36 0.62 2.16 0.92

 55. 1.25 1.59 0.74 2.46 1.11

 50. 1.53 1.87 0.86 2.83 1.34

 45. 2.06 2.14 0.99 3.20 1.62

 40. 3.09 2.51 1.25 3.72 1.98

 35. 4.88 3.04 1.53 4.98 2.39

 30. 6.74 3.65 2.00 7.71 3.05

 25. 8.59 4.96 2.65 11.95 3.94

 20. 10.44 7.75 3.63 19.09 5.41

 15. 12.56 15.78 5.09 24.91 10.23

 10. 16.08 27.55 10.39 35.50 19.25

 5. 21.61 76.91 27.23 65.49 41.76

 2. 32.74 122.05 72.78 92.69 90.13

 1. 37.87 149.77 114.52 108.17 122.34

-----------------------------------------------------------------

The recessions, or hydrograph slopes after the 

peaks from spring runoff, have the typical falling-limb 

curvilinear shape (better seen in fig. 24B) from about 

May 9 to about June 13. The change in slope after 

about June 13 indicates the beginning of streamflow 

dominated by base flow. The portion of the hydrographs from about June 13 through about July 11 

appears to consist almost entirely of base flow and 

indicates differences in base-flow contributions to 

streamflow. After about July 11, direct runoff from 

thunderstorms increased streamflow above base-flow 

levels at the four short-term sites. 

The slope of the hydrographs during the 

June 13 through July 11 period indicates the rate at 

which ground water drains from the system to supply 

base flow to streams. The hydrographs for STR–1, 

STR–2, and STR–3 indicate about the same rate 

during the nearly 4-week period (fig. 24A). The 

hydrograph for STR–4, however, spans nearly three 

log cycles and shows zero streamflow (plotted as 

0.0001 ft3

/s) several times during the period, indicating that at times there is no water to sustain 

streamflow. 

In order to help assess the occurrence of base 

flow in other areas of the watershed, synoptic measurements of streamflow were made at several sites (fig. 23 

and table 15). The measurements were made in a short 

period of time (4–6 hours) to minimize the influence 

of changing conditions. The results of these measurements, together with those from the short-term sites, 

indicate that on a unit area basis, two general base-flow 

conditions characterize the watershed. The first and 

more prevalent condition is that of base-flow rates of 

about thousandths of cubic feet per second per square 

mile, or less. This first category is representative of 

much of the watershed and includes many sites where 

zero streamflow was measured on July 6, 2001. The 

second category, which appears to be restricted mostly 

to the southwest part of the watershed, is that of baseflow rates of hundredths or even tenths of cubic feet per 

second per square mile. Measurements at sites SNCG1, 

SNCG2, SNFZ1, SNFZ2, and SNSP2 consistently fall 

into this category based on measurements made in the 

summer and fall of 2001.

The synoptic measurements also help to document two other important conditions in the Turkey Creek 

watershed. The measurements made at sites SNSP3 and 

SNQA2 are on the same tributary to North Turkey Creek 

upstream and downstream from a tens-of-acres area 

containing alluvial-fill deposits. The measurements 

made at these sites indicate that alluvial areas can, at 

times, store ground water and sustain streamflow. 

The series of seven synoptic measurements 

of upstream diversions from Turkey Creek made 

at the Independent Highline ditch (upstream from 

station 06710995 and referred to as DIV in table 15), 

station 06710995, and station 06710992 can be 

used to evaluate how records from station 06710995 

represent ground-water discharge conditions. For 

synoptic measurements made during periods of base 

flow at nearly the same times, the sum of measurements from the Independent Highline and station 

06710995 should be about equal to the measurement 

at station 06710992, assuming that there are no losses 

or gains in the relatively short intervening stream 

reach between the two stream gages. The mean ratio 

between the sum and streamflow at station 06170992 

is 0.93 for the seven sets of measurements and indicates that there is about a 7-percent loss between 

the two stations. Because of the observations of
50 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

Table 14. Measured precipitation and streamflow in and near the Turkey Creek watershed

[Note: Water year, one year period beginning in October and ending in September; Precipitation is from 

 Cheesman (Colorado Climate Center, 2002); all measurements in inches; Min, minimum; Max, maximum, Var, 

 variance; --, no data]

------------------------------------------------------------------------------------------------------------------

 Sorted by water year Sorted by measured precipitation

------------------------------------------------------ ----------------------------------------------------------

 Streamflow Streamflow

 -------------------------------------- ------------------------------------------

Water Precip- Station Station Station Station Water Precip- Station Station Station Station 

year itation 06710992 06710995 06711000 06711040 year itation 06710992 06710995 06711000 06711040

--------------------------------------------------------------------------------------------------------------------

1943 -- -- -- 0.75 -- 1943 -- -- -- 0.75 -- 

1944 -- -- -- 3.55 -- 1944 -- -- -- 3.55 -- 

1945 -- -- -- 0.45 -- 1945 -- -- -- 0.45 -- 

1946 -- -- -- 0.39 -- 1946 -- -- -- 0.39 -- 

1947 -- -- -- 2.94 -- 1947 -- -- -- 2.94 -- 

1948 -- -- -- 3.23 -- 1948 -- -- -- 3.23 -- 

1949 15.85 -- -- 2.90 -- 1962 9.47 -- -- -- -- 

1950 14.28 -- -- 0.60 -- 1956 10.31 -- -- -- -- 

 

1951 14.10 -- -- 0.55 -- 1978 11.97 -- -- -- -- 

1952 13.73 -- -- 1.98 -- 1964 12.40 -- -- -- -- 

1953 14.35 -- -- 0.78 -- 1989 12.76 -- -- -- 0.58 

1954 13.18 -- -- -- -- 1960 13.00 -- -- -- -- 

1955 18.29 -- -- -- -- 1954 13.18 -- -- -- -- 

 

1956 10.31 -- -- -- -- 1993 13.35 -- -- -- -- 

1957 19.98 -- -- -- -- 1996 13.57 -- -- -- -- 

1958 15.17 -- -- -- -- 1952 13.73 -- -- 1.98 -- 

1959 14.50 -- -- -- -- 1968 13.85 -- -- -- -- 

1960 13.00 -- -- -- -- 1951 14.10 -- -- 0.55 -- 

 

1961 20.87 -- -- -- -- 1966 14.14 -- -- -- -- 

1962 9.47 -- -- -- -- 1950 14.28 -- -- 0.60 -- 

1963 15.66 -- -- -- -- 1953 14.35 -- -- 0.78 -- 

1964 12.40 -- -- -- -- 1959 14.50 -- -- -- -- 

1965 18.28 -- -- -- -- 1986 14.57 -- -- -- -- 

 -- 

1966 14.14 -- -- -- -- 1972 14.62 -- -- -- -- 

1967 17.08 -- -- -- -- 1975 14.97 -- -- -- -- 

1968 13.85 -- -- -- -- 1958 15.17 -- -- -- -- 

1969 20.42 -- -- -- -- 1963 15.66 -- -- -- -- 

1970 23.15 -- -- -- -- 1949 15.85 -- -- 2.90 -- 

 -- 

1971 17.59 -- -- -- -- 1981 15.99 -- -- -- -- 

1972 14.62 -- -- -- -- 1974 16.21 -- -- -- -- 

1973 20.53 -- -- -- -- 1980 16.25 -- -- -- -- 

1974 16.21 -- -- -- -- 1979 16.48 -- -- -- -- 

1975 14.97 -- -- -- -- 1999 16.51 -- 3.29 -- -- 

 -- 

1976 17.46 -- -- -- -- 1977 16.67 -- -- -- -- 

1977 16.67 -- -- -- -- 2001 16.41 -- 0.86 -- -- 

1978 11.97 -- -- -- -- 2000 17.07 -- 0.96 -- -- 

1979 16.48 -- -- -- -- 1967 17.08 -- -- -- -- 

1980 16.25 -- -- -- -- 1997 17.25 -- -- -- -- 

 

1981 15.99 -- -- -- -- 1994 17.36 -- -- -- -- 

1982 22.16 -- -- -- -- 1976 17.46 -- -- -- -- 

1983 19.13 -- -- -- -- 1971 17.59 -- -- -- -- 

1984 20.19 -- -- -- -- 1988 17.73 -- -- -- 3.54 

1985 18.76 -- -- -- -- 1965 18.28 -- -- -- -- 

 

1986 14.57 -- -- -- -- 1955 18.29 -- -- -- -- 

1987 19.36 -- -- -- 5.83 1992 18.58 -- -- -- -- 

1988 17.73 -- -- -- 3.54 1985 18.76 -- -- -- -- 

1989 12.76 -- -- -- 0.58 1998 18.76 -- -- -- -- 

1990 20.09 -- -- -- -- 1991 18.77 -- -- -- -- 

 -- 

1991 18.77 -- -- -- -- 1983 19.13 -- -- -- -- 

1992 18.58 -- -- -- -- 1987 19.36 -- -- -- 5.83 

1993 13.35 -- -- -- -- 1957 19.98 -- -- -- -- 

1994 17.36 -- -- -- -- 1990 20.09 -- -- -- -- 

1995 20.96 -- -- -- -- 1984 20.19 -- -- -- -- 

 

1996 13.57 -- -- -- -- 1969 20.42 -- -- -- -- 

1997 17.25 -- -- -- -- 1973 20.53 -- -- -- -- 

1998 18.76 -- -- -- -- 1961 20.87 -- -- -- -- 

1999 16.51 -- 3.29 -- -- 1995 20.96 -- -- -- -- 

2000 17.07 -- 0.96 -- -- 1982 22.16 -- -- -- -- 

 

2001 16.21 0.81 -- -- -- 1970 23.15 -- -- -- -- 

------------

Mean 16.49 

Min 9.47 

Max 23.15 

Var 8.95 

------------------------------------------------------------------------------------------------------------------
HYDROLOGIC CONDITIONS 51

streamflow near station 06710995 described in 

the “Watershed Conditions” section, it seems reasonable to conclude that the losses are occurring near 

station 06710995.

Ground-Water Conditions

Ground-water conditions are described on the 

basis of time-series measurements of water levels in 

wells and a synoptic round of water-level measurements 

made in fall 2001. In addition, an analysis of SEO wellconstruction data is used to characterize ground-water 

conditions, especially reported well yields. In this 

report, the term “reported yield” is used to represent the 

estimated well yield, typically developed using undocumented techniques at the time of well construction, indicated in SEO records. 

Time-Series Water Levels

Figure 25 illustrates fluctuations in ground-water 

levels in monitoring wells in the Turkey Creek watershed. The first five sets of graphs in figure 25 illustrate 

historical (left graph) and contemporary (right graph) 

ground-water levels at the same well. The remainder 

of the graphs illustrate fluctuations in contemporary 

ground-water levels measured as part of this study. 

Precipitation from the Cheesman climatologic site is 

shown across the top of the graph for historical waterlevel comparisons and from a variety of local rain gages 

for contemporary water-level comparisons. 

Ground-water levels fluctuate seasonally in the 

monitoring wells; the highest water levels correlate 

directly with snowmelt and precipitation and indicate 

the effects from recharge. After the seasonal highs, 

water levels recede at a relatively constant rate during

Parmalee Gulch

S. Turkey Creek

N. Turkey Cr

Giant Gulch

Turkey Creek Iowa Gulch

Lone Pine

Estates

Wild Rose Grange

Marshdale

Tiny Town

Indian

Hills

Fenders

Phillipsburg

Homewood Park

Oehlmann

Park

Conifer

8

To Morrison

C470

Shadow Mountain Road

N. Turkey Creek Rd

Parma lee Gulch

Road

285

285

Marshdale

D

A

B

E

D C

F

L M

H

P

G

I

J

K

N

O 39°32'24"

39°30'36"

39°34'12"

39°36'

39°37'48"

105°23'24" 105 105°21'36" °19'48" 105°18' 105°16'12" 105°14'24" 105°12'36" 105°10'48"

EXPLANATION

Study area

Contributing drainage

 area

 

Subbasins

Drainage

Roads

Subbasin code

Population centers

Short-term discharge

 record site

Site and discharge

 measurement for

 07/06/2001

0

0 0.5 1 1.5 2 2.5 3 KILOMETERS

0.5 1 1.5 2 2.5 3 MILES

STR-1

Main stem discharge

 measurement site

Discharge measurement

 site not measured 07/06/2001

0–

0.0010

0.0011–

0.010

0.011–

1.00

STR-2

STR-1

STR-2

STR-4

STR-3

STR-4

STR-3

SNSG3

SWL01

SWF01

SWB02

06710995

06710992

SNSP4

SNSP3

SNSP2

SNSG4

SNQS2

SNQS1

SNQA2

SNGN9

SNGN6

SNFZ2

SNFZ1

SNCG2

SNCG1 SNGN8

SNSG2

SNQA1

SNGN7

SNGN5

SNGN4

SNGN3

SNSP1

SNGN10

Base modified from U.S. Geological Survey

digital data for 1:24,000 maps

Figure 23. Locations of short-term record stream gages and sites of synoptic streamflow measurements.
52 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

rainless periods until additional recharge occurs. 

This pattern is most readily seen in the contemporary 

ground-water levels where snowmelt and the accumulation of precipitation from March through May 1999 

are accompanied by the highest recorded water levels 

in almost all of the monitoring wells (fig. 25). Precipitation in July and August 1999 is correlated with a 

slight rise in water levels in most wells. Precipitation 

was less in 2000 and 2001 than in 1999, but rises in 

ground-water levels in 2000 and 2001 still can be associated with precipitation events. The time lag between 

precipitation and rise in water levels may be as much 

an effect of measurement frequency, which is daily for 

precipitation and monthly for water levels, as it is of 

recharge rate (fig. 25). Contemporary water levels in 

most of the monitoring wells have fluctuated from 3 to 

20 ft. Water levels fluctuated about 80 ft in MH4 and 

about 50 ft in MH7.

Historical ground-water levels also appear to 

correlate with precipitation events and had large fluctuations over time (fig. 25). In the early 1970’s, water 

levels were measured more frequently than in the 

late 1970’s through 1980’s; therefore, the earlier part 

of the hydrograph shows more seasonal variability. In 

general, the hydrographs indicate an overall decrease 

in water levels occurred at MH1, MH5, and MH9 from 

STR-1

STR-2

STR-3

STR-4

Watershed

Site locations shown in figure 23

EXPLANATION

2

1

0

LOG DAILY MEAN DISCHARGE,

IN CUBIC FEET PER SECOND PER SQUARE MILE –1

–2

–3

–4

–5

2.5

2.0

1.5

DAILY MEAN DISCHARGE,

IN CUBIC FEET PER SECOND PER SQUARE MILE 1.0

0.5

0

11 18

APRIL MAY JUNE

2001

JULY

25 2 9 16 23 30 6 13 20 27 4 11 18 25 1

–0.5

A

B

Figure 24. Hydrographs from short-term records of streamflow (A, log; B, arithmetic).
HYDROLOGIC CONDITIONS 53

1974 through 1983. Contemporary water levels 

(1998–2001) at these three wells are similar to water 

levels measured 1974–83. However, the decrease does 

not continue at the same rate into the contemporary 

1999–2000 period, possibly the result of a change in 

climatic conditions. Water levels at MH10 appear to 

be relatively stable through time. MH8 shows a slight 

decrease in water level (about 4 ft) from the 1970’s 

through 2000. The annual low (lowest ground-water 

elevation, generally occurring during fall or winter 

months when ground-water recharge is minimal or 

nonexistent) for MH1, MH5, MH8, MH9, and MH10 

for the contemporary period are comparable to annual 

lows measured 1974–83, but these wells represent 

only a fraction of the Turkey Creek watershed.

Continuous water-level measurements were 

collected at three monitoring wells (MH1, MH5, and 

MH8) from May to October of 2001 and are shown 

in figure 25. Water levels in MH1 and MH8 are more 

directly affected by smaller amounts of precipitation 

than the water level at MH5. Precipitation of approximately 0.5 inch on August 8 resulted in a water-level 

rise that peaked near August 13 in MH1 and on 

August 10 in MH8. There was no apparent water-level 

rise in MH5 from the same precipitation event. Precipitation of approximately 0.9 inch on September 7 

resulted in an increase of about 0.2 ft over 2 days in 

MH8, while only a very small or no water-level rise 

occurred in MH1 and MH5. 

Table 15. Synoptic measurements of streamflow made at rock group sites and surface-water sampling sites

[Local identifier; 8 U.S. Geological Survey digit station number, or a 2 to 4 character prefix to a sequential 

 number indicating geology of contributing drainage area (SP for intrusive, GN for metamorphic, FZ for fault zone, 

 CG for Pikes Peak Granite, QA or alluvium, QS for alluvium and intrusive, and SG for intrusive and metamorphic), 

 additional local identifiers indicate Independent Highline ditch (DIV), the sum of DIV and station 06710995 (TOT), 

 the ratio of TOT and 06710992 RATIO), sites that were part of the surface-water sampling network (characters 1 and 

 2 = SW); cda, contributing drainage area, in square miles; cfs, discharge in cubic feet per second; cfsm, unit area 

 discharge in cubic feet per second per square mile; --, no data]

 

--------------------------------------------------------------------------------------------------------------------------

 Date of measurement in month, day, 2-digit year format

 ------------------------------------------------------------------------------------------------ 

 070601 092001 102501 110201 110601 110901 111301

 ------------ ------------ ------------ ------------ ------------ ------------ ------------ 

 Local 

identifier cda cfs cfsm cfs cfsm cfs cfsm cfs cfsm cfs cfsm cfs cfsm cfs cfsm

--------------------------------------------------------------------------------------------------------------------------

SNCG1 0.27 0.009 0.0333 0.007 0.0259 0.0024 0.0089 -- -- -- -- -- -- -- --

SNCG2 0.27 0.040 0.1481 0.030 0.1111 0.013 0.0481 -- -- -- -- -- -- -- --

SNFZ1 2.33 0.196 0.0841 0.162 0.0695 0.111 0.0476 -- -- -- -- -- -- -- --

SNFZ2 1.72 0.097 0.0564 0.040 0.0233 0.030 0.0174 -- -- -- -- -- -- -- --

 

SNGN1 -- 0.000 0.000 -- -- -- -- -- -- -- -- -- -- -- --

SNGN2 -- 0.000 0.000 -- -- -- -- -- -- -- -- -- -- -- --

SNGN3 -- 0.000 0.000 -- -- -- -- -- -- -- -- -- -- -- --

SNGN4 -- 0.000 0.000 -- -- -- -- -- -- -- -- -- -- -- --

SNGN5 -- 0.000 0.000 -- -- -- -- -- -- -- -- -- -- -- --

SNGN6 0.69 0.119 0.1725 0.0025 0.0036 0.001 0.0014 -- -- -- -- -- -- -- --

SNGN7 -- 0.000 0.000 -- -- -- -- -- -- -- -- -- -- -- --

SNGN8 -- 0.000 0.000 -- -- -- -- -- -- -- -- -- -- -- --

SNGN9 2.90 0.007 0.0024 0.030 0.0103 0.017 0.0059 -- -- -- -- -- -- -- --

SNGN10 0.41 0.0003 0.0007 0.0017 0.0041 0.0011 0.0027 -- -- -- -- -- -- -- --

 

SNSP1 0.70 0.000 0.000 0.000 0.000 0.000 0.000 -- -- -- -- -- -- -- --

SNSP2 0.96 0.068 0.0708 0.045 0.0469 0.035 0.0365 -- -- -- -- -- -- -- --

SNSP3 -- 0.000 0.000 -- -- -- -- -- -- -- -- -- -- -- -- 

SNSP4 1.00 0.001 0.0010 0.0002 0.0002 0.0045 0.0045 -- -- -- -- -- -- -- --

 

SNQA1 -- 0.000 0.000 -- -- -- -- -- -- -- -- -- -- -- --

SNQA2 0.65 0.0005 0.0008 0.000 0.000 0.0001 0.0002 -- -- -- -- -- -- -- --

SNQS1 0.46 0.0041 0.0089 0.000 0.000 0.000 0.000 -- -- -- -- -- -- -- --

SNQS2 0.37 0.0024 0.0065 0.0029 0.0078 0.0041 0.0127 -- -- -- -- -- -- -- --

SNSG3 0.41 -- -- 0.000 0.000 0.0004 0.0010 -- -- -- -- -- -- -- --

SNSG4 1.34 0.0013 0.0010 0.000 0.000 0.000 0.000 -- -- -- -- -- -- -- --

DIV -- 0.160 -- 0.470 -- 0.423 -- 0.380 -- 0.513 -- 0.423 -- 0.876 -- 

TOT -- 0.160 0.0034 0.586 0.0124 0.480 0.0102 0.393 0.0083 0.596 0.0126 0.458 0.0097 0.921 0.0195

RATIO -- 0.76 0.74 1.11 1.07 1.23 1.18 0.86 0.83 0.91 0.88 0.68 0.66 0.99 0.97 

SWF01 24.56 0.230 0.0094 0.540 0.0220 0.354 0.0140 -- -- -- -- -- -- -- --

SWB02 13.32 0.076 0.0057 0.083 0.0062 0.051 0.0038 -- -- -- -- -- -- -- --

SWL01 2.00 -- -- -- -- 0.017 0.0085 -- -- -- -- -- -- -- --

06710992 45.80 0.210 0.0046 0.530 0.0116 0.390 0.0085 0.456 0.0100 0.657 0.0143 0.670 0.0146 0.927 0.0202

06710995 47.42 0.000 -- 0.116 -- 0.057 -- 0.013 -- 0.083 -- 0.035 -- 0.045 -- 

--------------------------------------------------------------------------------------------------------------------------
54 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

 

DEPTH TO WATER, IN FEET BELOW

LAND SURFACE 

PRECIPITATION,

IN INCHES

0

1

2

0

10

20

30

1970 1975 1980 1985

Note: Precipitation from Cheesman Reservoir

393821105161001 (MH1)

DEPTH TO WATER, IN FEET BELOW

LAND SURFACE 

PRECIPITATION,

IN INCHES

0

1

2

20

30

40

1970 1975 1980 1985

Note: Precipitation from Cheesman Reservoir

393350105184301 (MH5)

DEPTH TO WATER, IN FEET BELOW

LAND SURFACE 

PRECIPITATION,

IN INCHES

0

1

2

0

10

20

1970 1975 1980 1985

Note: Precipitation from Cheesman Reservoir

393350105184301 (MH8)

DEPTH TO WATER, IN FEET BELOW

LAND SURFACE 

PRECIPITATION,

IN INCHES

0

1

2

0

10

20

30

Note: Precipitation from RG8

MH1

DEPTH TO WATER, IN FEET BELOW

LAND SURFACE 

PRECIPITATION,

IN INCHES

0

1

2

20

30

40

Note: Precipitation from RG4

MH5

DEPTH TO WATER, IN FEET BELOW

LAND SURFACE 

PRECIPITATION,

IN INCHES

0

1

2

0

10

20

1998 1999 1981 2000 2002

1998 1999 1981 2000 2002

1998 1999 1981 2000 2002

Note: Precipitation from RG3

MH8

Figure 25. Ground-water fluctuations in water-level monitoring wells.
HYDROLOGIC CONDITIONS 55

DEPTH TO WATER, IN FEET BELOW

LAND SURFACE 

PRECIPITATION,

IN INCHES

0

1

2

0

10

20

1998 1999 2000 2001 2002

Note: Precipitation from RG8

MH2

DEPTH TO WATER, IN FEET BELOW

LAND SURFACE 

PRECIPITATION,

IN INCHES

0

1

2

10

20

30

1970 1975 1980 1985

Note: Precipitation from Cheesman Reservoir

392958105164601 (MH10)

DEPTH TO WATER, IN FEET BELOW

LAND SURFACE 

PRECIPITATION,

IN INCHES

0

1

2

20

30

40

1970 1975 1980 1985

Note: Precipitation from Cheesman Reservoir

392959105164501 (MH9)

DEPTH TO WATER, IN FEET BELOW

LAND SURFACE 

PRECIPITATION,

IN INCHES

0

1

2

0

30

10

20

30

1998 1999 2000 2001 2002

Note: Precipitation from RG3

MH9

DEPTH TO WATER, IN FEET BELOW

LAND SURFACE 

PRECIPITATION,

IN INCHES

0

1

2

10

20

30

1998 1999 2000 2001 2002

Note: Precipitation from RG16

MH10

DEPTH TO WATER, IN FEET BELOW

LAND SURFACE 

PRECIPITATION,

IN INCHES

0

1

2

0

10

20

1998 1999 2000 2001 2002

Note: Precipitation from RG4

MH3

Figure 25. Ground-water fluctuations in water-level monitoring wells—Continued.
56 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001 DEPTH TO WATER, IN FEET BELOW LAND SURFACE PRECIPITATION, IN INCHES

0

1

2

20

40

60

80

1998 1999 2001 2000 2002

Note: Precipitation from RG3

MH7

DEPTH TO WATER, IN FEET BELOW

LAND SURFACE 

PRECIPITATION,

IN INCHES

0

1

2

10

20

30

1998 1999 2001 2000 2002

Note: Precipitation from RG16

MH11

DEPTH TO WATER, IN FEET BELOW

LAND SURFACE 

PRECIPITATION,

IN INCHES

0

1

2

0

20

10

30

1998 1999 2001 2000 2002

Note: Precipitation from RG4

MH6.3

DEPTH TO WATER, IN FEET BELOW

LAND SURFACE 

PRECIPITATION,

IN INCHES

0

1

2

0

10

1998 1999 2001 2000 2002

Note: Precipitation from RG4

MH6.1

DEPTH TO WATER, IN FEET BELOW

LAND SURFACE PRECIPITATION, IN INCHES0

1

2

70

30

110

1998 1999 2001 2000 2002

Note: Precipitation from RG4

MH4

DEPTH TO WATER, IN FEET BELOW

LAND SURFACE 

PRECIPITATION,

IN INCHES

0

1

2

0

10

20

1998 1999 2001 2000 2002

Note: Precipitation from RG4

MH6.2

Figure 25. Ground-water fluctuations in water-level monitoring wells—Continued.
HYDROLOGIC CONDITIONS 57

Synoptic Water Levels

Synoptic measurements of depth to water were 

obtained September 24–October 4, 2001. Measurements were made at wells identified in a spatial analysis of depth-to-water data from the SEO. Variogram 

analysis was performed to estimate range; the method 

of variogram analyses is discussed in the Appendix. 

As a result of the variogram analysis, a grid of square 

cells, with dimensions of about 0.5 mi by 0.5 mi, was 

created over the watershed with the goal of finding one 

candidate well for water-level measurement in each 

cell; wells that had reported total depths of less than 

75 ft were not included. The mean and median depth 

to water in each cell was calculated from the SEO 

data. First priority was given to wells that had previously been sampled as a part of this study. Next 

priority was given to wells from the SEO database that 

had a depths to water nearest the mean or, if skewed, 

median depth to water for that cell. Jefferson County 

personnel contacted each well owner to gain permission to make depth-to-water measurements. A few 

wells also were added to the network during field 

activities, usually in areas that had not been represented in the defined network because the well owner 

could not be reached by phone. The network established in this exercise has the potential of becoming a 

regularly visited water-level monitoring network that 

could be used to evaluate ground-water conditions 

over the long term.

Measurements from the network described 

above were used to construct the water-table map 

shown in figure 26, and the depth-to-water contour 

map shown in figure 27. Well locations were determined in the field by Global Positioning System 

(GPS) equipment. Measured, and presumed, static 

depth-to-water level measurements from 134 wells 

were subtracted from land-surface elevations estimated from a topographic map. The resulting groundwater elevations were plotted and, assuming homogeneous and isotropic conditions, contoured to construct 

a water-table map (fig. 26). In a similar manner, 

depth-to-water measurements were plotted and 

contoured to construct a depth-to-water contour 

map (fig. 27).

The water-table surface in figure 26 generally 

appears to be a continuous surface that approximates 

the topography of the watershed, indicating that ground 

water generally exists in an unconfined state. Watertable contours can indicate direction and relative rate of 

ground-water movement. For example, along the southwest edge of watershed, the water-table contours indicate that ground-water flow is from the southwestern 

boundary of the watershed, perpendicular to the watertable contours, to the northeast toward North Turkey 

Creek (fig. 26). Throughout the Turkey Creek watershed, these inferred flow directions are important for 

determining general direction and rate of movement of 

ground water in the crystalline rocks or to streamflow. 

In general, the water-table map indicates that ground 

water moves from high to low topographic areas. There DEPTH TO WATER, IN FEET BELOW LAND SURFACE PRECIPITATION, IN INCHES

0

1

2

0

20

10

1998 1999 2001 2000 2002

Note: Precipitation from RG8

MH13

DEPTH TO WATER, IN FEET BELOW

LAND SURFACE 

PRECIPITATION,

IN INCHES

0

1

2

0

10

1998 1999 2001 2000 2002

Note: Precipitation from RG16

MH12

Figure 25. Ground-water fluctuations in water-level monitoring wells—Continued.
58 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

are no obvious differences in the water table due to 

bedrock geology or environmental conditions at the 

current spatial resolution. 

The depth-to-water map in figure 27 indicates 

that there are some areas of the watershed where 

depths to water are generally less than 50 ft; the mean 

depth to water is about 105 ft. The map also indicates 

that there are some areas where depths to water are 

greater than 300 feet; in general, areas of the largest 

depths to water are where local relief is greatest. Some 

areas of the watershed are not contoured because they 

are outside the extent of the computer-generated grid 

shown in the figure 27, which represents the geometric 

extent of the well network.

Analysis of State Engineer Well-Construction Data

Univariate statistics for all available wellconstruction data were prepared to summarize well 

characteristics in the watershed (table 16). Variogram 

analysis was used to evaluate spatial relations of 

reported well yields in the watershed.

Univariate Statistics

Univariate statistics for well-construction 

details indicate a mean reported yield of 5.56 gallons 

per minute (gal/min) and a median of 4 gal/min. The 

statistics also indicate that the distribution of reported 

yields is somewhat skewed as a result of a few reports

Parmalee Gulch

S. Turkey Creek

N. Turkey Cr

Giant Gulch

Turkey Creek Iowa Gulch

Lone Pine

Estates

Wild Rose Grange

Marshdale

Tiny Town

Indian

Hills

Fenders

Phillipsburg

Homewood Park

Oehlmann

Park

Conifer

8

To Morrison

C470

Shadow Mountain Road

N. Turkey Creek Rd

Parma lee Gulch

Road

285

285

Marshdale





D

A

B

E

D

C

F

L

M

H

P

G

I

J

K

N

O

39°32'24"

39°30'36"

39°34'12"

39°36'

39°37'48"

105°23'24" 105 105°21'36" °19'48" 105°18' 105°16'12" 105°14'24" 105°12'36" 105°10'48"

EXPLANATION

Study area

Subbasins

Drainage

Roads

Ground-water

 elevation contour, 

 in feet

Subbasin code

Population center

Well and ground-water

 elevation, in feet

0

0 0.5 1 1.5 2 2.5 3 KILOMETERS

0.5 1 1.5 2 2.5 3 MILES

7711

7742

7974

7974

7866

7749

7763

8240 8341

7625

7585

7582

7780

8002

7828 7685

7649

7716 7738

7661 7794

8002 8017

8042

8080

7343

7236

7231

7550

7029

6925

6547

6499

6805

7232

7020

7228

7156

7249

7324

7377

7473

7430

7041

7137 7174

8216

8280 8581 8635

8582

9139

9381

9311

9550

8949 8929 8842

8442

8626

8459

8484

8419

8712 8732 8700

9100

9000

7900

7900

7400

7500

7300 7200 7100

7000

6900

6800

6700

6600

6500

8300

8300

8400

8100

8200

8000

7900

7800

7900

7400

76007700

8000

9200

8800

8700

8900

9500

9400

8100

8000

8200

8300

8500

8600

8200

8400

8100

8724

9727

9677

9307

7406

7434 7326 7371

7070

74217188 7129

7845

7872

7570

7813 7380

8081

7789

7739

7884

7847

7774

7644

7787 7938

8134

8079

7684

7610

7309

8209

8208

8145

8019 7920

7884

8246

8188

8046

8049

8135

8143

8435

8257

8154 8250

8145 7844

7873

8091

8070

8712

7880

7943

7976

7981

7783

7896

7906

8036

8016 7884

Base modified from U.S. Geological Survey

digital data for 1:24,000 maps

Figure 26. Ground-water table in the Turkey Creek watershed, September 2001.
HYDROLOGIC CONDITIONS 59

of relatively high yield wells. Wells with reported 

yields in the range of greater than 15 to 50 gal/min 

represent about the upper 1.5 percent of the distribution and were defined as “reported high-yield wells” 

for the purposes of this study. The locations for these 

23 reported high-yield wells are shown in figure 5.

Eight of the 14 rock types listed in table 1 had 

well-construction data available for fewer than 15 

wells. By aggregating individual rock types into the 

four groups identified in the “Geologic Framework” 

section—metamorphic, intrusive, fault zone, and Pikes 

Peak Granite—the rock group statistics become more 

robust. Table 17 compares depth to water, well depth, 

and water-table elevation among the rock groups. 

Wells completed in metamorphic and intrusive rocks 

had water levels at about the same depth (means of 

about 88.65 and about 93.35 ft below land surface, 

respectively) which was about 16 to 22 ft deeper than

Figure 27. Contours of depth to ground water for September 2001.

300

300

100

250

150 22

Extent of computergenerated grid

River

Study area outline

Contour of depth to

 water, in feet

Well and depth to

 ground water, in feet

Value

Greater depth to water

Smaller depth to water

EXPLANATION

67

31

76

49

101

21 17

368

126

159 169

101 25

95

77

228

204

105

20

28

67

375 59

402

35

54

76

149

162

290

191

33

98

10

22

174

350

51

2

92

40

92

13

103 77

110

150

110

101

185

12 48

30

78

27 87

7

33

55

70

157

36

162

324

40

138 87

102 159

12

167 109

5

73

215 23

184 56

114 149 98

116 449

0

19

70

201

67

64 74 60

55 329

14

101

45

11

82

42

188

211

190 61

142

85

15

18

24

83

101

12

5

129

26

195

332

48 129

287 312

137

55

128

27

50

15

62

17

32

15

56

100

100

100

100

100

50

50

150

200

150

100

100

150

200

250

250

100

150

50

50 50

100

100

50

100

50

50

100

100

100

100

50

50

150

150

150

150

200

200

200

300

350

250

150

150

100

150

100

50

50

100

150

200

250

200

50

150

200

50

150

150

150

150

250

350

100

150

100

50
60 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

water levels in wells completed in the Pikes Peak 

Granite (mean of 72.7 ft below land surface) or faultzone rocks (mean of 70.9 ft below land surface). Total 

well depth for wells completed in fault-zone rocks 

(293 ft below land surface) are shallower on average 

than for wells completed in the other rock groups. 

Water-table elevation also differs by rock group, with 

highest elevations in the Pikes Peak Granite and lowest 

elevations in the metamorphic rocks. 

Because reported well yields are probably the 

best index of aquifer characteristics available in the 

well-construction details, and because a goal of this 

study is to identify any spatial patterns in aquifer 

characteristics, univariate statistics also were prepared 

for reported well yields, rock types, and rock groups 

(table 18). Uncertainty associated with the reported 

well yields results from use of several undocumented 

methods for determining the reported yield during a 

period of nearly five decades.

The rock-group statistics indicate some variation in means for reported well yields, but the differences are not large and do not, by themselves, provide 

a basis for defining differences in aquifer characteristics. The combination of the highest mean for reported 

yield and a variance that is much higher than the 

variance for other rock groups, however, indicates that 

the fault-zone rock group is capable of yielding relatively large amounts of water compared to other rock 

groups. The Pikes Peak Granite is similar, at least in 

mean, to the fault-zone rocks for reported well yields.

Results in table 18 also include information 

describing reported well yields through time that, 

for wells with a reported date of construction, indicate 

the number of wells drilled per decade is, in general, 

increasing. There was a large increase in the population and the number of buildings in the watershed in 

the 1970’s and smaller increases in the 1980’s and 

1990’s. Substantial increases in the reported number of 

wells drilled between the 1960’s and 1970’s are likely 

a result, at least in part, of widespread acceptance of 

record-keeping practices. It is clear, however, that 

there are many more wells in the watershed today 

(2001) than there were in the 1950’s, or even the 

1970’s.

Figure 28 provides a graphical summary of 

well construction, reported well yields, and well depths. 

Reported well depths have increased with time. The 

graph of reported well yield and well depth in figure 28 

indicates there is no strong relation between well yield 

and well depth in the Turkey Creek watershed. 

Table 16. Univariate statistics and correlations for well-construction characteristics

[Note: yield, reported well yield in gallons per minute; td, total well depth, 

 in feet below land surface; dtw, depth to water in feet below land surface; 

 prfln, casing perforation length, in feet; tperf, depth to top of perforated 

 length, in feet below land surface; bperf, depth to bottom of perforated length,

 in feet below land surface; Stddev, standard deviation; Q1, 25th percentile; Q3, 

 75th percentile; Min, minimum; Max, maximum; N, number of cases; --, not 

 applicable]

---------------------------------------------------------------------------

 Univariate statistics

---------------------------------------------------------------------------

Variable Mean Median Stddev Q1 Q3 Min Max N

--------- ------ -------- -------- ---- ---- ----- ----- ---

yield 5.56 4 5.37 2 7 0.06 50 1109

td 340.19 305 164.12 225 425 6 902 1116

dtw 89.13 70 75.62 40 108 1 519 1075

prfln 154.04 100 107.44 100 200 4 663 631

tperf 219.91 195 147.35 105 300 9 820 631

bperf 373.95 350 165.35 260 477 55 900 631

===========================================================================

 Pearson correlations 

---------------------------------------------------------------------------

Variable tperf bperf prfln yield td dtw

-------- -------- -------- -------- -------- -------- -------

tperf 1.00000 0.76962 -0.18742 -0.05043 0.76338 0.54985

bperf -- 1.00000 0.48294 -0.10946 0.98141 0.56203

prfln -- -- 1.00000 -0.09924 0.46291 0.11056

yield -- -- -- 1.00000 -0.12423 -0.12020

td -- -- -- -- 1.00000 0.56226

dtw -- -- -- -- -- 1.00000

 

 Valid cases = 626 Missing cases = 490

---------------------------------------------------------------------------
HYDROLOGIC CONDITIONS 61

Variogram Analysis

The variogram analysis, which is similar 

to work by Drew and others (1999), consisted of 

preparing a variogram surface map for all reported 

yields. The process of constructing a variogram 

surface map is described in the Appendix. The analysis was done for two sets of reported well yields: 

first, for all reported yields and second, for all reported 

yields except the arbitrarily defined reported highyield wells (reported yields greater than 15 gal/min). 

Some basic spatial relations were simply evaluated as a preliminary step to the variogram analysis to 

determine if conditions of spatial stationarity were 

acceptable. For the purposes of this study stationarity 

can be described as a condition of no large spatial 

trends in the reported well yields. The spatial-trend 

evaluations used as part of this study, simple linear 

regression of reported yields relative to spatial coordinates and an initial inspection of computed variogram, 

indicated stationary data.

Table 17. Descriptive statistics for selected physical characteristics of permitted wells from the State Engineers Office, 

by rock group

 [NGVD29, Nation Geodetic Vertical Datum 1929; NA indicates number of wells with records of total depth but no record of depth to water]

Intrusive Metamorphic Fault zone Pikes Peak Granite

Depth to water

(feet)

Mean 93.35 88.65 70.92 72.69

Minimum 1.00 4.00 5.00 20.00

Maximum 410.00 519.00 300.00 170.00

Standard deviation 76.42 76.46 59.95 43.77

25th percentile 40.00 40.00 40.00 41.75

50th percentile 71.00 70.00 50.00 66.50

75th percentile 120.00 105.75 85.00 85.75

Number of wells 315 741 44 16

NA 11 23 7 0

Well depth

(feet)

Mean 349.42 339.45 293.25 322.19

Minimum 10.00 6.00 10.00 120.00

Maximum 900.00 902.00 660.00 710.00

Standard deviation 160.90 165.78 163.54 138.51

25th percentile 250.00 221.00 183.75 250.00

50th percentile 320.00 305.00 265.00 301.00

75th percentile 441.00 425.00 388.75 340.00

Number of wells 315 741 44 16

NA 0 0 0 0

Water-table elevation

(feet above NGVD29)

Mean 8225.67 7759.55 8134.40 9169.65

Minimum 6589.52 6464.88 6878.16 8918.32

Maximum 9731.76 9482.48 8754.32 9528.40

Standard deviation 639.93 426.14 396.88 175.30

25th percentile 7868.72 7448.06 8098.32 9061.00

50th percentile 8159.00 7796.56 8242.64 9156.12

75th percentile 8564.08 8039.28 8301.68 9212.70

Number of wells 315 741 44 16

NA 11 23 7 0
62 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

The results of the variogram analysis provide 

two principal findings (fig. 29). The first finding is 

that there is a substantial contrast in the variogram 

surface map prepared using all reported yields and 

the map prepared using all but the reported highyield wells. The variogram surface map prepared 

with all but the reported high-yield wells (fig. 29A) 

consists of mostly uniformly colored cells and has 

a relatively uniform appearance, indicating that 

there is a relatively constant amount of variability 

in reported well yields in the Turkey Creek watershed regardless of the well spacing. When the 

reported high-yield wells are included, the variogram 

surface map consists of mostly blue with some bright 

(yellow and red) cells, indicating relatively higher 

amounts of variability with increasing well spacings 

(fig. 29B).

The observed differences described in the 

previous paragraph correspond to a conceptual model 

in which there is a relatively uniform background condition, or fabric, that is accented with local deviations 

caused by wells with reported yields greater than 

15 gal/min. In a practical sense, this indicates that 

there can be variability at very short spacings—that 

is, two wells located very close to each other will 

not necessarily have the same yield. This condition 

appears to be relatively constant over the entire watershed; however, a relatively persistent presence, which 

can be thought of as a larger fabric, of higher yield 

wells exists. 

The second finding has to do with directional 

characteristics of the variogram surface maps. Each 

map, but in particular the map including reported highyield wells (on the basis of a general cluster of lighter 

colored blocks has a tendency to indicate from low to 

high contrast in the northwest-to-southeast direction. 

In effect, this is the orientation of the so-called larger 

fabric. The northwest-to-southeast direction corresponds with the orientation of structural fabric 

described in the “Geologic Framework” section and 

indicates that high-yield features may align themselves 

with this fabric.

Table 18. Univariate statistics for reported well yields by rock type and group and 

through time

[Note: Category, except for ALL, which refers to all rock types together, refers

 to rock types defined in table 1, or rock groups defined in “Geologic Framework” 

 section; N, number of cases; --, not applicable; <, before]

 

------------------------------------------------------------------------------

Category Mean Variance Median Skewness Minimum Maximum N

------------------------------------------------------------------------------

ALL 5.56 28.86 4.00 2.83 0.06 50.00 1109

 

 By rock type

 

GMG 15.00 -- 15.00 -- 15.00 15.00 1

P 10.50 0.50 10.50 0.00 10.00 11.00 2

XGNM 4.50 24.50 4.50 0.00 1.00 8.00 2

FG 4.53 10.84 3.55 0.42 2.00 9.00 4

XGQG 1.93 1.47 1.40 0.78 1.00 4.00 10

FGU 2.88 2.52 3.00 -0.26 0.25 5.00 12

XHCS 2.56 2.57 2.25 0.33 0.75 5.00 12

XMGD 3.67 9.16 2.50 1.17 1.00 11.00 14

YPP 6.91 21.86 5.00 0.77 1.00 15.00 15

FLTZN 7.33 83.88 4.00 2.78 0.75 50.00 43

XF 4.47 14.34 3.00 1.60 0.06 15.00 44

XB 5.41 25.08 3.50 2.01 0.20 30.00 163

YSP 5.60 29.18 4.00 3.25 0.40 50.00 285

XM 5.70 28.11 4.00 2.46 0.20 50.00 450

 

 By rock group

 

METAMORPHIC 5.51 26.12 4.00 2.38 0.06 50.00 677

INTRUSIVE 5.39 27.90 4.00 3.30 0.40 50.00 309

FAULT ZONE 7.33 83.88 4.00 2.78 0.75 50.00 43

PIKES PEAK GRANITE 6.91 21.86 5.00 0.77 1.00 15.00 15

 All rock types in time

 

1950 - < 1960 2.00 -- 2.00 -- 2.00 2.00 1

1960 - < 1970 2.80 3.70 2.00 0.73 1.00 6.00 5

1970 - < 1980 5.46 24.17 3.40 1.67 0.25 30.00 191

1980 - < 1990 7.03 51.75 5.00 2.65 0.06 50.00 133

1990 - < 1998 5.98 36.28 4.00 3.34 0.25 50.00 296

------------------------------------------------------------------------------
HYDROLOGIC CONDITIONS 63

Water-Quality Characteristics in the 

Turkey Creek Watershed

General water quality is described in this 

report with univariate statistics, Stiff and trilinear 

diagrams (Hem, 1985), maps of areal distribution 

of selected constituents, and comparison of sample 

results with applicable State (Colorado Department 

of Public Health and Environment, 1998) and Federal 

(U.S. Environmental Protection Agency, 1996) waterquality standards. Also presented are additional 

discussions of tritium results, chloride/bromide ratios, 

wastewater-compound analyses, mass balances 

of chloride sources, and seasonality of specific 

conductance.

General Water-Quality Characteristics

Statistical summaries of quarterly ground-water 

and surface-water samples collected in the Turkey Creek 

watershed are shown in table 19 and table 20. Censored 

values in table 19 and table 20 are those concentrations 

that are less than reporting levels for the laboratory. 

The Stiff diagrams in figure 30 of composite 

ground water and composite surface water illustrate that 

the general chemical composition of water in Turkey 

Creek watershed is calcium bicarbonate type water. 

This is consistent with other studies that have reported 

on the chemical composition of water from crystalline 

rocks along the Front Range (Bruce and McMahon, 

1997). A feature of the Stiff diagram for composite 

surface water is a stronger chloride component than 

in the Stiff diagram for composite ground water, which 

indicates that chloride concentrations from surfacewater samples were, in general, elevated compared to 

chloride concentrations in samples of ground water. In 

fact, calcium-chloride type water similar to the diagram 

shown for GWO10 was observed in both ground and 

surface water; however, the chloride component was 

more pronounced in surface-water samples. 

Trilinear diagrams are plots of relative major-ion 

composition that represent the chemical signature of the 

major-ion concentrations of a water sample as a single 

point on a diagram. Waters with different major-ion 

chemistry plot in different locations on the diagram, 

allowing clusters of points to be interpreted as being 

distinct. A trilinear diagram indicating results for all 

ground-water and surface-water samples collected for 

this study is shown in figure 31. Similar to the Stiff 

diagrams for composite ground water and surface water, 

the trilinear diagram indicates that the most common 

anion differences between ground-water and surfacewater major-ion chemistry are the presence of more 

chloride, less bicarbonate, and less sulfate in surfacewater samples. For cations, the pattern in the trilinear 

diagram shows somewhat more sodium and less 

calcium in most surface-water samples than in most 

ground-water samples. 

50

40

30

20

10

0

0 200 400

REPORTED WELL DEPTH, IN FEET BELOW LAND SURFACE

600 800 1,000 1950 1960 1970

REPORTED DATE OF WELL CONSTRUCTION

1980 1990 2000

1,000

REPORTED WELL DEPTH, IN FEET BELOW LAND SURFACE

REPORTED YIELD, IN GALLONS PER MINUTE

800

600

400

200

0

Figure 28. Well yield and total depth for State Engineers Office permitted wells.
64 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

4,800

4,000

3,200

2,400

1,600

800

0

–800

–1,600

–2,400

–3,200

–4,000

–4,800

4,800

4,000

3,200

2,400

1,600

800

0

–800

–1,600

–2,400

–3,200

–4,000

–4,800

–4,800 –4,400 –3,200 –2,400 –1,600 –800 0 800 1,600 2,400 3,200 4,000 4,800

LAG, IN METERS

LAG, IN METERS LAG, IN METERS

A

B

Pairs range from 9 to 1,359

Values range from 3 to 118

40 x lags at 100 -- 40 y lags at 100

Pairs range from 9 to 1,332

Values range from 3 to 35

40 x lags at 100 -- 40 y lags at 100

Lag—Indicates interval, in x or y direction,

 in which pairs have been accumulated

Value—Indicates variogram value in given cell

Pairs—Indicates number of pairs used to

 determine value in given cell

EXPLANATION

Figure 29. Variogram surface maps.
HYDROLOGIC CONDITIONS 65

Table 19. Univariate statistics for water-quality properties and constituents in selected ground-water samples collected September 1998 through November 1999[Note: Q1, concentration at the 25th percentile; Q3, concentration at the 75th percentile; Min, minimum; Max, maximum; N, number of samples; Percent < rpl, percentage of samples with concentration less than the reporting level; NPDWS, National Primary Drinking Water Standards, or MCL, Maximum Contaminant Level established by the U.S. Environmental Protection Agency (1999); NSDWS, National Secondary Drinking Water Standards, established by the U.S. Environmental  Protection Agency (1991); --, not applicable; Exceptions, number of samples that exceeded the relevant regulation; μs, microsiemens; cm, centimeter; mg/L,  milligrams per liter; μg/L, micrograms per liter; oC, degrees Celsius; N, nitrogen]-------------------------------------------------------------------------------------------------------------------------------------------------------------- Detections Censored values  ------------------------------------------------------- --------------------- Percent Excep- ExcepProperty or constituent Mean Median Q1 Q3 Min Max N Mean Median N < rpl NPDWS tions NSDWS tions--------------------------------------------------------------------------------------------------------------------------------------------------------------Specific conductance (μs/cm at 25oC) 330.36 313.00 199.00 414.00 22.00 1090.00 363 -- -- 0 -- -- -- -- --pH (standard units) 7.07 7.05 6.63 7.53 5.18 8.47 358 -- -- 0 -- -- -- 6.5-8.5 63Temperature (degrees Celsius) 9.14 9.00 7.80 10.20 2.70 19.30 365 -- -- 0 -- -- -- -- --Dissolved oxygen (mg/L) 3.75 3.29 1.87 5.61 0.03 10.50 358 -- -- 0 -- -- -- -- --Hardness, total 136.61 120.00 82.00 180.00 0.16 550.00 269 -- -- 0 -- -- -- -- --Calcium, dissolved (mg/L) 39.20 36.30 22.60 52.31 0.10 146.00 269 0.01 0.01 1 0.37 -- -- -- --Calcium, total (mg/L) 39.75 40.30 24.02 51.60 3.98 77.40 22 -- -- 0 -- -- -- -- --Magnesium, dissolved (mg/L) 9.41 7.90 4.96 12.71 0.04 46.00 270 -- -- 0 -- -- -- -- --Magnesium, total (mg/L) 9.61 8.54 6.01 14.40 0.85 19.90 22 -- -- 0 -- -- -- -- --Sodium, dissolved (mg/L) 15.94 11.30 8.86 17.83 3.49 116.34 270 -- -- 0 -- -- -- -- --Sodium, total (mg/L) 15.22 11.10 8.47 16.85 5.87 50.40 22 -- -- 0 -- -- -- -- --Potassium, dissolved (mg/L) 1.93 1.73 1.10 2.68 0.30 6.26 142 2.00 2.00 59 29.35 -- -- -- --Potassium, total (mg/L) 2.91 2.55 2.27 3.28 2.18 4.64 7 2.00 2.00 15 68.18 -- -- -- --Alkalinity, total (mg/L) 118.15 120.00 80.00 160.00 7.12 270.00 273 5.00 5.00 3 1.09 -- -- -- --Sulfate (mg/L) 22.05 11.80 7.00 18.00 1.00 2500.00 273 1.00 1.00 3 1.09 -- -- 250 1Chloride (mg/L) 24.95 6.78 3.05 36.30 0.50 230.00 269 0.50 0.50 6 2.18 -- -- 250 0Fluoride (mg/L) 0.88 0.62 0.39 1.11 0.15 4.70 242 0.27 0.20 34 12.32 4.00 3 2.00 0Silicon, dissolved (mg/L) 10.17 9.80 8.20 11.50 4.30 16.10 93 -- -- 0 -- -- -- -- --Silicon, total (mg/L) 8.70 8.70 -- -- 8.70 8.70 1 -- -- 0 -- -- -- -- --Total organic carbon (mg/L) 3.02 2.50 1.80 3.72 1.00 11.20 110 0.06 0.05 346 75.88 -- -- -- --Ammonia, as N (mg/L) 0.10 0.10 0.08 0.11 0.05 0.12 8 0.06 0.05 346 97.74 -- -- -- --Nitrate/Nitrite, as N (mg/L) 2.26 1.02 0.40 2.67 0.05 18.50 309 0.05 0.05 45 12.71 10.0 14 -- --Nitrite (mg/L) -- -- -- -- -- -- 0 0.20 0.20 13 -- 1.00 0 -- --Phosphorus, total (mg/L) 0.10 0.06 0.03 0.11 0.02 0.71 64 0.03 0.02 291 81.97 -- -- -- --Aluminum, dissolved (μg/L) 54.33 47.00 28.50 80.50 12.00 118.00 6 25.37 40.00 164 96.47 -- -- -- --Aluminum, total (μg/L) 266.12 98.50 52.50 622.00 41.00 797.00 8 40.00 40.00 14 63.64 -- -- 200 3Antimony, dissolved (μg/L) 4.60 5.00 3.90 6.00 0.60 6.00 6 1.97 0.60 257 97.72 -- -- -- --Antimony, total (μg/L) -- -- -- -- -- -- 0 0.60 0.60 23 -- 6.00 0 -- --Arsenic, dissolved (μg/L) 1.25 1.10 1.00 1.65 1.00 1.80 4 1.02 1.00 259 98.48 -- -- -- --Arsenic, total (μg/L) -- -- -- -- -- -- 0 1.00 1.00 10 -- 5.00 0 -- --Barium, dissolved (μg/L) 67.62 46.60 19.00 84.25 1.00 638.00 160 1.00 1.00 10 5.88 -- -- -- --Barium, total (μg/L) 88.91 63.00 21.75 101.25 1.00 604.00 22 -- -- 0 -- 200 2 -- --Beryllium, dissolved (μg/L) 0.62 0.50 0.40 0.90 0.30 1.00 5 0.61 1.00 165 97.06 -- -- -- --Beryllium, total (μg/L) -- -- -- -- -- -- 0 1.00 1.00 22 -- 4.00 0 -- --Boron, dissolved (μg/L) 29.33 13.00 9.00 36.50 7.00 155.00 109 7.67 8.00 61 35.88 -- -- -- --Boron, total (μg/L) 27.44 16.50 10.00 32.50 7.00 156.00 18 7.00 7.00 4 18.18 -- -- -- --Cadmium, dissolved) (μg/L) 0.23 0.20 0.20 0.30 0.20 0.30 3 0.47 0.60 260 98.86 -- -- -- --Cadmium, total) (μg/L) -- -- -- -- -- -- 0 0.60 0.60 23 -- 5.00 0 -- --Chromium, dissolved) (μg/L) 1.57 1.60 1.20 1.90 1.20 1.90 3 0.74 0.80 260 98.86 -- -- -- --Chromium, total) (μg/L) 1.60 1.60 -- -- 1.60 1.60 1 4.56 7.00 132 99.25 100 0 -- --
66 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001 Cobalt, dissolved) (μg/L) 0.61 0.40 0.30 0.50 0.30 7.00 38 4.56 7.00 132 77.65 -- -- -- -- Cobalt, total (μg/L) 7.00 7.00 7.00 7.00 7.00 7.00 3 7.00 7.00 19 86.36 -- -- -- -- Table 19. Univariate statistics for water-quality properties and constituents in selected ground-water samples collected September 1998 through November 1999—Continued [Note: Q1, concentration at the 25th percentile; Q3, concentration at the 75th percentile; Min, minimum; Max, maximum; N, number of samples; Percent < rpl, percentage of samples with concentration less than the reporting level; NPDWS, National Primary Drinking Water Standards, or MCL, Maximum Contaminant Level established by the U.S. Environmental Protection Agency (1999); NSDWS, National Secondary Drinking Water Standards, established by the U.S. Environmental Protection Agency (1991); --, not applicable; Exceptions, number of samples that exceeded the relevant regulation; μs, microsiemens; cm, centimeter; mg/L, milligrams per liter; μg/L, micrograms per liter; oC, degrees Celsius; N, nitrogen] --------------------------------------------------------------------------------------------------------------------------------------------------------------

 Detections Censored values  ------------------------------------------------------- --------------------- Percent Excep- ExcepVariable Mean Median Q1 Q3 Min Max N Mean Median N < rpl NPDWS tions NSDWS tions --------------------------------------------------------------------------------------------------------------------------------------------------------------Copper, dissolved (μg/L) 57.50 27.00 12.00 71.00 0.60 549.40 251 1.42 2.00 12 4.56 -- -- -- --Copper, total (μg/L) 30.67 20.60 7.30 34.80 0.70 239.00 23 -- -- 0 -- 1300 0 1000 0Iron, dissolved (μg/L) 27.96 10.00 7.00 25.00 4.00 389.00 47 4.57 5.00 123 72.35 -- -- -- --Iron, total (μg/L) 4580.75 13.50 6.00 252.25 5.00 69430.00 16 5.00 5.00 6 27.27 -- -- 300 4Lead, dissolved (μg/L) 1.34 1.05 0.80 1.70 0.60 4.60 80 0.98 0.60 183 69.58 -- -- -- --Lead, total (μg/L) 2.24 2.80 0.85 3.35 0.80 3.60 5 0.60 0.60 18 78.26 15.0 0 -- --Manganese, dissolved (μg/L) 20.53 2.30 1.00 12.00 0.30 286.00 125 0.72 1.00 45 26.47 -- -- -- --Manganese, total (μg/L) 53.68 6.00 1.00 31.00 1.00 446.00 19 6.08 9.00 104 84.55 -- -- 50.0 3Molybdenum, dissolved (μg/L) 13.04 10.75 3.40 21.70 1.20 50.00 66 6.08 9.00 104 61.18 -- -- -- --Molybdenum, total (μg/L) 21.00 18.00 16.00 27.50 16.00 30.00 5 9.00 9.00 17 77.27 -- -- -- --Nickel, dissolved (μg/L) 0.93 0.80 0.50 1.10 0.40 3.40 38 7.23 11.00 132 77.65 -- -- -- --Nickel, total (μg/L) -- -- -- -- -- -- 0 11.00 11.00 22 -- -- -- -- --Selenium, dissolved (μg/L) 2.99 2.00 1.35 3.55 1.00 11.40 25 1.00 1.00 238 90.49 -- -- -- --Selenium, total (μg/L) 2.80 2.80 -- -- 2.50 3.10 2 1.00 1.00 21 91.30 50.0 0 -- --Silver, dissolved (μg/L) -- -- -- -- -- -- 0 0.39 0.20 263 -- -- -- -- --Silver, total (μg/L) -- -- -- -- -- -- 0 0.20 0.20 23 -- -- -- 100 0Thallium, dissolved (μg/L) -- -- -- -- -- -- 0 1.70 0.60 263 -- -- -- -- --Thallium, total (μg/L) -- -- -- -- -- -- 0 1.00 1.00 168 -- 2.00 0 -- --Titanium, dissolved (μg/L) 1.50 1.50 -- -- 1.00 2.00 2 1.00 1.00 168 98.82 -- -- -- --Titanium, total (μg/L) 6.00 6.00 -- -- 2.00 10.00 2 1.00 1.00 20 90.91 -- -- -- --Vanadium, dissolved (μg/L) 0.96 0.80 0.50 1.33 0.50 2.60 30 4.45 7.00 140 82.35 -- -- -- --Vanadium, total (μg/L) -- -- -- -- -- -- 0 7.00 7.00 22 -- -- -- -- --Zinc, dissolved (μg/L) 169.68 13.00 7.00 64.50 2.50 4763.00 135 3.37 4.00 35 20.59 -- -- -- --Zinc, total (μg/L) 297.21 15.00 5.00 323.00 4.00 2908.00 19 -0.01 -0.01 1 5.00 -- -- 5000 0---------------------------------------------------------------------------------------------------------------------------------------------------------------
HYDROLOGIC CONDITIONS 67

Table 20. Univariate statistics for water-quality properties and constituents in selected surface-water samples collected September 1998 through November 1999[Note: Q1, concentration at the 25th percentile; Q3, concentration at the 75th percentile; Min, minimum; Max, maximum; N, number of samples; Percent < rpl,  percent of samples with concentration less than the reporting level; -- not applicable; In-stream standards as defined by Colorado Department of Public  Health and Environment, 2000; *, a maximum C-degree increase over a 4-hour period is acceptable; **, several censored values at < .2 may include values  greater than the in-stream standard; μs, microsiemens; cm, centimeter, mg/L, milligrams per liter, μg/L, micrograms per liter; oC, degrees Celsius; N, nitrogen]-------------------------------------------------------------------------------------------------------------------------------------------------------------- 

 In-stream standards 

 Detections Censored values ------------------------------  ------------------------------------------------------- --------------------- Percent Excep- ExcepVariable Mean Median Q1 Q3 Min Max N Mean Median N < rpl Acute tions Chronic tions --------------------------------------------------------------------------------------------------------------------------------------------------------------Discharge (in cfs) 1.56 0.33 0.14 0.96 0.01 14.60 71 -- -- 0 -- -- -- -- -- Specific conductance (in μs/cm) 596.22 457.00 293.75 652.50 106.00 2270.00 78 -- -- 0 -- -- -- -- --pH (in standard units) 8.00 7.99 7.80 8.21 7.11 8.70 78 -- -- 0 -- -- -- 6.5-9 0 Temperature (in degrees Celsius) 9.47 10.60 5.10 14.00 0.30 20.30 79 -- -- 0 -- -- -- 20* 1 Dissolved oxygen [in mg/L] 9.02 8.75 7.90 10.62 3.01 14.40 58 -- -- 0 -- -- -- 6.0 4 Hardness (total) 242.09 150.00 81.75 245.00 25.00 1300.00 56 -- -- 0 -- -- -- -- -- Calcium (dissolved) [in mg/L] 71.73 41.79 23.62 66.53 7.01 464.00 56 -- -- 0 -- -- -- -- -- Calcium (total) [in mg/L] 73.61 42.20 24.80 72.77 7.10 460.00 53 -- -- 0 -- -- -- -- -- Magnesium (dissolved) [in mg/L] 15.62 10.36 5.76 19.35 1.83 66.40 56 -- -- 0 -- -- -- -- -- Magnesium (total) [in mg/L] 16.38 10.96 6.34 20.00 1.91 70.98 53 -- -- 0 -- -- -- -- -- Sodium (dissolved) [in mg/L] 35.74 27.50 20.55 39.83 6.13 162.99 56 -- -- 0 -- -- -- -- -- Sodium (total) [in mg/L] 37.15 27.30 21.00 39.35 6.07 174.22 53 -- -- 0 -- -- -- -- -- Potassium (dissolved) [in mg/L] 3.15 2.81 2.43 3.51 0.91 8.00 34 2.00 2.00 7 17.07 -- -- -- -- Potassium (total) [in mg/L] 3.73 3.35 2.68 4.00 0.90 11.00 50 2.00 2.00 3 5.66 -- -- -- -- Alkalinity (total) [in mg/L] 115.21 98.50 66.35 160.00 24.80 330.00 58 -- -- 0 -- -- -- -- -- Sulfate (in mg/L) 70.63 12.65 9.00 20.77 2.50 1100.00 58 -- -- 0 -- -- -- -- -- Chloride (in mg/L) 78.89 64.50 34.33 96.40 5.41 390.00 58 -- -- 0 -- -- -- -- -- Fluoride (in mg/L) 0.51 0.46 0.37 0.55 0.13 2.70 55 2.00 0.50 3 5.17 -- -- -- -- Silicon (dissolved) [in mg/L] 7.43 7.25 6.62 8.15 6.20 9.10 20 -- -- 0 -- -- -- -- -- Silicon (total) [in mg/L] 8.19 8.00 7.00 8.60 6.90 12.80 17 -- -- 0 -- -- -- -- -- Total organic carbon 4.77 4.30 3.40 6.18 0.35 13.80 76 0.06 0.05 76 50.00 -- -- -- -- Ammonia (as N) [in mg/L] 0.06 0.06 -- -- 0.06 0.07 2 0.06 0.05 76 97.44 0.43 1 0.02 1 Nitrate/Nitrite (as N) [in mg/L) 0.52 0.36 0.12 0.87 0.05 1.47 47 0.05 0.05 31 39.74 -- -- -- -- Nitrite (in mg/L) -- -- -- -- -- -- 0 0.20 0.20 10 -- -- -- -- -- Phosphorus (total) [in mg/L] 0.04 0.04 0.03 0.05 0.02 0.15 33 0.03 0.02 45 57.69 -- -- -- -- Aluminum (dissolved) [in μg/L] 130.75 122.00 88.75 181.50 87.00 192.00 4 27.81 40.00 32 88.89 750 1 87 1Aluminum (total) [in μg/L] 364.62 113.00 72.50 208.50 34.00 4048.00 29 40.00 40.00 4 12.12 -- -- -- -- Antimony (dissolved) [in μg/L] -- -- -- -- -- -- 0 1.86 0.60 56 -- -- -- -- --Antimony (total) [in μg/L] 2.85 2.85 -- -- 0.70 5.00 2 1.98 0.60 48 96.00 -- -- -- -- Arsenic (dissolved) [in μg/L] 1.08 1.05 1.00 1.15 1.00 1.30 6 1.00 1.00 50 89.29 340 0 150 0 Arsenic (total) [in μg/L] 1.70 1.70 -- -- 1.00 2.40 2 -- -- 0 -- -- -- -- -- Barium (dissolved) [in μg/L] 94.99 83.35 43.88 149.15 14.50 210.00 36 -- -- 0 -- -- -- -- -- Barium (total) [in μg/L] 104.82 96.50 46.50 155.70 13.40 238.00 33 -- -- 0 -- -- -- -- -- Beryllium (dissolved) [in μg/L] 2.10 2.10 -- -- 2.10 2.10 1 0.66 1.00 35 97.22 -- -- -- -- Beryllium (total) [in μg/L] 1.00 1.00 -- -- 1.00 1.00 1 0.62 1.00 32 96.97 -- -- -- -- Boron (dissolved) [in μg/L] 41.21 27.00 18.75 52.00 11.00 156.00 34 8.00 8.00 2 5.56 -- -- -- -- Boron (total) [in μg/L] 50.88 37.00 27.50 65.00 11.00 166.00 33 -- -- 0 -- -- -- -- -- 
68 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001 Cadmium (dissolved) [in μg/L] 0.20 0.20 -- -- 0.20 0.20 1 0.49 0.60 55 98.21 5.86 0 2.77 0 Cadmium (total) [in μg/L] 0.33 0.20 0.20 0.60 0.20 0.60 3 0.49 0.60 47 94.00 -- -- -- -- Chromium (dissolved) [in μg/L] -- -- -- -- -- -- 0 0.76 0.80 56 -- 722 0 93.7 0 Chromium (total) [in μg/L] 1.90 1.50 1.15 2.30 0.90 4.70 9 4.77 7.00 30 76.92 -- -- -- -- Cobalt (dissolved) [in μg/L] 0.45 0.35 0.30 0.60 0.30 0.90 6 4.77 7.00 30 83.33 -- -- -- -- Cobalt (total) [in μg/L] 0.38 0.40 0.30 0.45 0.30 0.50 5 4.37 7.00 28 84.85 -- -- -- -- Table 20. Univariate statistics for water-quality properties and constituents in selected surface-water samples collected September 1998 through November 1999—Continued Note: Q1, concentration at the 25th percentile; Q3, concentration at the 75th percentile; Min, minimum; Max, maximum; N, number of samples; Percent < rpl, percent of samples with concentration less than the reporting level; -- not applicable; In-stream standards as defined by Colorado Department of Public Health and Environment, 2000; *, a maximum C-degree increase over a 4-hour period is acceptable; **, several censored values at < .2 may include values 

 greater than the in-stream standard; μs, microsiemens; cm, centimeter, mg/L, milligrams per liter, μg/L, micrograms per liter; oC, degrees Celsius; N, nitrogen]-------------------------------------------------------------------------------------------------------------------------------------------------------------- 

 In-stream standards 

 Detections Censored values ------------------------------  ------------------------------------------------------- --------------------- Percent Excep- ExcepVariable Mean Median Q1 Q3 Min Max N Mean Median N < rpl Acute tions Chronic tions ---------------------------------- ------- ------ ------ ------ ----- ------- --- ----- ------ --- ------ ----- ------ ------- ------Copper (dissolved) [in μg/L] 1.54 1.00 0.70 1.35 0.60 10.90 25 1.32 2.00 31 55.36 17.7 0 11.5 0 Copper (total) [in μg/L] 2.38 1.60 1.20 2.00 0.70 12.60 35 2.00 2.00 15 30.00 -- -- -- -- Iron (dissolved) [in μg/L] 64.47 32.00 16.75 62.75 9.00 393.00 34 5.00 5.00 2 5.56 -- -- -- -- Iron (total) [in μg/L] 494.74 269.00 170.00 451.00 45.00 2973.00 31 4.50 4.50 2 6.06 -- -- 1000 2 Lead (dissolved) [in μg/L] 5.82 1.35 0.75 12.85 0.60 23.30 10 0.85 0.60 46 82.14 88.8 0 3.46 0 Lead (total) [in μg/L] 2.13 1.10 0.70 4.60 0.70 4.60 3 0.60 0.60 31 91.18 -- -- -- -- Manganese (dissolved) [in μg/L] 76.06 30.00 17.60 112.10 1.20 345.00 35 1.00 1.00 1 2.78 3280 0 1810 0 Manganese (total) [in μg/L] 91.40 33.40 22.30 137.80 3.00 424.00 31 5.71 9.00 34 52.31 -- -- -- -- Molybdenum (dissolved) [in μg/L] 1.30 1.30 -- -- 1.00 1.60 2 5.71 9.00 34 94.44 -- -- -- -- Molybdenum (total) [in μg/L] 1.43 1.20 1.20 1.90 1.20 1.90 3 5.53 9.00 30 90.91 -- -- -- -- Nickel (dissolved) [in μg/L] 0.91 0.75 0.62 1.35 0.40 1.50 8 7.97 11.00 28 77.78 599 0 65.6 0 Nickel (total) [in μg/L] 0.54 0.40 0.40 0.75 0.40 1.00 5 6.84 11.00 28 84.85 -- -- -- -- Selenium (dissolved) [in μg/L] 1.82 1.80 1.55 2.10 1.50 2.10 5 1.00 1.00 51 91.07 18.4 0 4.6 0Selenium (total) [in υg/L] 1.95 1.45 1.15 3.25 1.10 3.80 4 1.00 1.00 46 92.00 -- -- -- -- Silver (dissolved) [in μg/L] 0.80 0.80 -- -- 0.80 0.80 1 0.36 0.20 55 98.21 3.42 0 0.54 0 Silver (total) [in μg/L] 1.00 1.00 -- -- 1.00 1.00 1 0.38 0.20 49 98.00 -- -- -- -- Thallium (dissolved) [in μg/L] -- -- -- -- -- -- 0 1.57 0.60 56 -- -- -- 15 0Thallium (total) [in μg/L] 4.67 4.00 4.00 6.00 4.00 6.00 3 1.00 1.00 35 92.11 -- -- -- -- Titanium (dissolved) [in μg/L] 2.00 2.00 -- -- 2.00 2.00 1 1.00 1.00 35 97.22 -- -- -- --Titanium (total) [in μg/L] 12.11 2.91 1.51 6.00 1.24 90.00 19 1.00 1.00 14 42.42 -- -- -- -- Vanadium (dissolved) [in μg/L] 3.18 0.60 0.50 4.60 0.50 14.00 9 5.07 7.00 27 75.00 -- -- -- --Vanadium (total) [in μg/L] 3.70 3.10 0.60 4.90 0.50 11.00 7 4.50 7.00 26 78.79 -- -- -- -- Zinc (dissolved) [in μg/L] 4.78 4.00 4.00 5.93 2.20 10.20 16 3.10 4.00 20 55.56 150 0 151 0 Zinc (total) [in μg/L] 8.77 7.00 5.00 10.35 3.50 23.00 21 -- -- 0 -- -- -- -- -- -------------------------------------------------------------------------------------------------------------------------------------------------------------
HYDROLOGIC CONDITIONS 69

Spatial differences in water quality can be 

characterized with plots of constituent ranges on 

maps of the watershed (figs. 32–35). Those constituents potentially associated with individual sewagedisposal system (ISDS) effluent are of greatest 

interest. Specific conductance, chloride, nitrate plus 

nitrite, and boron are associated with septic-tank 

effluent, and spatial concentration patterns could indicate ISDS influence. Specific conductance is an indicator of dissolved solids. Chloride in effluent is related 

to human consumption of salt and chlorine-based 

home products. Nitrate is an end-member product 

of nitrification of organic and ammonia nitrogen in 

human and animal waste. Boron is present in the 

waste from laundry and other cleaning products. 

In the specific-conductance map (fig. 32), few 

patterns are evident. Although there is variation in 

specific conductance, high and low values are relatively evenly distributed across the watershed. An 

exception is an area of lower specific-conductance 

values that can be seen in ground water in the southwestern part of the watershed in subwatersheds I, J, 

and K. When median values of concentration for water 

from the Pikes Peak Granite and water from a group of 

all other rock types are compared using the Wilcoxon 

rank-sum test (Helsel and Hirsch, 1992), differences in 

specific conductance, as well as all the major cations, 

chloride, sulfate, and nitrate plus nitrite all are significant at the 99.9 percent level (p < 0.001). Overall, 

specific conductance ranged from 22 to 1,090 μS/cm 

in ground water and 106 to 2,270 μS/cm in surface 

water. In general, the results of samples collected in 

this study indicate that surface water is slightly more 

concentrated than ground water.

Pearson correlation coefficient is a measure of 

the linear relation between two variables. A value of 

“zero” indicates no correlation and a value of “one” 

indicates a perfect linear relation. In dilute waters, 

quasilinear relations between specific conductance 

and major ions are expected due to consistent inputs 

of solutes derived from rock-weathering reactions 

(Drever, 1988; Morgan, 2000). A lack of good correlation may indicate a more complex geochemical evolution or additional sources of solutes. Water from 

chloride-poor rock might be expected to have a poor 

correlation of chloride with dissolved solids because 

chloride is derived from precipitation and not from the 

fractured rock. Sources of chloride such as ISDS’s and 

road salt also would tend to complicate correlation 

unless chloride concentrations were high enough to 

control overall dissolved-solids concentration. 

In the Turkey Creek watershed, major ions are 

positively correlated with specific conductance in both 

ground and surface water. Except for calcium and 

chloride, Pearson correlation coefficients are larger in 

surface-water samples than in ground-water samples. 

In ground-water samples, the correlation of specific 

conductance and nitrate plus nitrite was stronger than 

the specific-conductance correlations with sodium, 

potassium, sulfate, and silica. A simple ground-water 

system, based primarily on rock contact time and 

not influenced by the addition of solutes, might be 

expected to display stronger correlation coefficients 

than those reported here. Correlations of specific 

conductance with possible ISDS-related constituents

GWO10

Composite Surface Water

Composite Ground Water

Sodium and

Potassium

Calcium

Magnesium

Chloride and

Fluoride

Alkalinity

Sulfate

Nitrogen and

Phosphorus

Sodium and

Potassium

Calcium

Magnesium

Chloride and

Fluoride

Alkalinity

Sulfate

Nitrogen and

Phosphorus

Sodium and

Potassium

Calcium

Magnesium

Chloride and

Fluoride

Alkalinity

Sulfate

Nitrogen and

Phosphorus

Figure 30. Stiff diagrams of selected water-quality 

constituents in the Turkey Creek watershed.
70 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

were moderately strong to weak: chloride, 0.73 and 

0.78; nitrate plus nitrite, 0.34 and 0.61; boron, 0.87 

and 0.4 in surface-water and ground-water samples, 

respectively.

Chloride concentrations ranged from 5.41 to 

390 mg/L in surface-water samples (table 20) and 

from 0.5 to 230 mg/L in ground-water samples in the 

watershed (table 19). The distribution of moderate 

concentrations (greater than 5 mg/L, less than or equal 

to 35 mg/L) and high concentrations (greater than 

35 mg/L) shows no particular pattern (fig. 33). Lower 

concentrations of chloride were found in the area of 

low specific conductance in the southwestern part of 

the watershed. Correlations of chloride with possible 

ISDS-related constituents were weak: nitrate plus 

nitrite, 0.25 and 0.45; boron, 0.44, and 0.31 in surfacewater and ground-water samples, respectively.

The map of nitrate plus nitrite as nitrogen 

concentrations (fig. 34) shows low and moderate 

nitrate plus nitrite concentrations distributed 

throughout the watershed. Median concentrations of 

nitrate plus nitrite in ground water (1.0 mg/L) were 

higher than those in surface water (0.52 mg/L). Lower 

nitrate plus nitrite concentrations in surface water may 

be due in part to seasonal biological consumption. 

A few relatively high concentrations (greater than 

10 mg/L) were measured in ground-water samples 

from subbasins C and D, based on sampling results 

PERCENT

Calcium

Magnesium

Sodium plus Potassium

Chloride, Fluoride, Nitrite plus Nitrate

Carbonate plus Bicarbonate

Sulfate

Sulfate plus Chloride

Calcium plus Magnesium

PERCENT

PERCENT

Ground-water sample

Surface-water sample

EXPLANATION

100 100

80

60

0

20

40

60

80

100

20

0

40

0

20

40

80

100

60

0

20

40

80

100

60

80

60

40

20

10080

60

40

20

0

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

Figure 31. Trilinear diagram of quarterly ground-water and surface-water samples collected in the Turkey 

Creek watershed.
HYDROLOGIC CONDITIONS 71

from fall 1999; however, relatively high nitrate plus 

nitrite concentrations are not limited to subbasins C 

and D as results from other sampling rounds indicated 

relatively high concentrations for nitrate plus nitrite as 

nitrogen at other locations. Correlation of nitrate plus 

nitrite concentrations with boron were weak: boron, 

0.39 and 0.20 in surface-water and ground-water 

samples, respectively.

The map of boron concentrations (fig. 35) indicates a weak spatial trend of increasing boron concentration from west to east in ground water and upstream 

to downstream in surface water. Flynn and Barber 

(2000) reported that background concentrations of 

boron in ground and surface waters of the Colorado 

Front Range are in the range of 10 to 40 micrograms 

per liter (μg/L). In Turkey Creek ground-water 

samples, 86 percent of boron concentrations were less 

than 40 μg/L; the maximum was 155 μg/L. In Turkey 

Creek surface-water samples, 69 percent of boron 

concentrations were less than 40 μg/L; the maximum 

was 156 μg/L. The median boron concentration in 

surface water (27 μg/L) was higher than the median 

concentration in ground water (13 μg/L). 

Where applicable, concentrations in ground 

water were compared to U.S. Environmental Protection 

Agency National Primary Drinking Water Standards 

(NPDWS) (U.S. Environmental Protection Agency, 

1999) and National Secondary Drinking Water

Parmalee Gulch

S. Turkey Creek

N. Turkey Cr

Giant Gulch

Turkey Creek Iowa Gulch

Lone Pine

Estates

Wild Rose Grange

Marshdale

Tiny Town

Indian

Hills

Fenders

Phillipsburg

Homewood Park

Oehlmann

Park

Conifer

8

To Morrison

C470

Shadow Mountain Road

N. Turkey Creek Rd

Parma lee Gulch

Road

285

285

Marshdale





D A

B

E

D C

F

L M

H

P

G

I

J

K

N

O

39°32'24"

39°30'36"

39°34'12"

39°36'

39°37'48"

105°23'24" 105 105°21'36" °19'48" 105°18' 105°16'12" 105°14'24" 105°12'36" 105°10'48"

EXPLANATION

Study area

Subbasins

Drainage

Roads

Subbasin code

Population centers

Specific conductance

 in ground water, 

 fall 1998, in μS/cm

0

0 0.5 1 1.5 2 2.5 3 KILOMETERS

0.5 1 1.5 2 2.5 3 MILES

Specific conductance

 in surface water,

 fall 1999, in μS/cm

50–250

251–400

401–1,090

126–450

451–700

701–2,260

Base modified from U.S. Geological Survey

digital data for 1:24,000 maps

Figure 32. Specific-conductance measurements in ground- and surface-water samples.
72 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

Standards (NSDWS) (U.S. Environmental Protection 

Agency, 1991) given in table 19. Comparison of 

surface-water concentrations to Colorado In-Stream 

Standards (Colorado Department of Public Health and 

Environment, 2000) is given in table 20. Concentrations in ground-water samples (table 19) occasionally exceeded NPDWS for fluoride (1.1 percent), 

nitrate plus nitrite (4.51 percent), and total barium 

(9.10 percent). NSDWS, which mostly refer to taste or 

esthetic properties, were not met for pH (17.6 percent), 

sulfate (0.37 percent), total aluminum (13.6 percent), 

total iron (18.2 percent), and dissolved manganese 

(2.4 percent). Concentrations in only a few surfacewater samples (table 20) exceeded standards for pH, 

dissolved oxygen, ammonia, dissolved aluminum, 

and total iron. 

Comparison to Historical Water-Quality Data

Contemporary ground-water quality data 

collected in Turkey Creek watershed from 1998 through 

1999 were compared to historical data collected from 

1972 through 1975. The Wilcoxon rank-sum test was 

used to test for differences in the median values and 

concentrations for the two time periods. Significantly 

(p-value less than 0.10, or 90-percent confidence) 

higher values and concentrations in the 1998–99 data 

were identified for specific conductance (p = <0.0001), 

calcium (p = 0.0023), magnesium (p = 0.0464), sodium 

(p = 0.0882), chloride (p = <0.0001), and nitrate plus 

nitrite (p = 0.0286). Although the contemporary data 

were collected from a network of wells (fig. 12) that is 

different than the network of wells for the historical data

Parmalee Gulch

S. Turkey Creek

N. Turkey Cr

Giant Gulch

Turkey Creek Iowa Gulch

Lone Pine

Estates

Wild Rose Grange

Marshdale

Tiny Town

Indian

Hills

Fenders

Phillipsburg

Homewood Park

Oehlmann

Park

Conifer

8

To Morrison

C470

Shadow Mountain Road

N. Turkey Creek Rd

Parma lee Gulch

Road

285

285

Marshdale





D A

B

E

D C

F

L M

H

P

G

I

J

K

N

O

39°32'24"

39°30'36"

39°34'12"

39°36'

39°37'48"

105°23'24" 105 105°21'36" °19'48" 105°18' 105°16'12" 105°14'24" 105°12'36" 105°10'48"

EXPLANATION

Study area

Subbasins

Drainage

Roads

Subbasin code

Population centers

Chloride in ground

 water, fall 1999, in

 mg/L

 Less than or equal to 5

 Greater than 5 and less

 than or equal to 35

 Greater than 35

Chloride in surface

 water, fall 1999, in

 mg/L

 Less than or equal to 5

 Greater than 5 and less

 than or equal to 35

 Greater than 35

0

0 0.5 1 1.5 2 2.5 3 KILOMETERS

0.5 1 1.5 2 2.5 3 MILES

Base modified from U.S. Geological Survey

digital data for 1:24,000 maps

Figure 33. Concentrations of chloride in ground- and surface-water samples.
HYDROLOGIC CONDITIONS 73

(fig. 6), both networks are widespread throughout 

the watershed, and the statistical differences for concentrations can be used to infer that water withdrawn 

from wells in Turkey Creek watershed is becoming 

more concentrated in dissolved solids and some major 

ions, and that nitrate plus nitrite concentrations have 

increased. 

Tritium

Tritium is an isotope of hydrogen with low 

natural background concentrations (about 8 tritium 

units [TU]) and short half-life (12.43 years). Tritium 

was released into the atmosphere in large quantities 

during above-ground testing of nuclear bombs primarily 

during the late 1950’s and early 1960’s. Tritium can be 

useful in making gross estimates of the recharge dates 

of ground water (the time water was isolated from the 

atmosphere). Based on correlation and interpolation 

(Michel, 1989) using tritium concentrations at 

Albuquerque, New Mexico, the expected year 2000 

tritium concentration in precipitation is approximately 

10 plus or minus 4 TU (seasonal differences can 

account for much of the variation) (fig. 36). Samples 

with a tritium concentration well below 10 TU probably 

have a large component of pre-bomb water (pre-1952). 

Samples with concentrations substantially greater 

than current precipitation concentration are probably 

composed predominantly of water recharged during 

the 1960’s. Intermediate concentrations are probably 

the result of mixtures of water of variable recharge 

dates.

Parmalee Gulch

S. T urkey Creek

N. Turkey Cr

Giant Gulch

Turk ey Cre ek Iowa Gulch

Lone Pine

Estates

Wild Rose Grange

Marshdale

Tiny Town

Indian

Hills

Fenders

Phillipsburg

Homewood Park

Oehlmann

Park

Conifer

8

To Morrison

C470

Shadow Mountain Road

N. Turkey Cree k Rd

Parma lee Gulch

Road

285

285

Marshdale

M

M

D

A

B

E

D C

F

L

M

H

P

G

I

J

K

N

O

39 32'24"

39 30'36"

39 34'12"

39 36'

39 37'48"

105 23'24" 105 19'48" 105 18' 105 16'12" 105 14'24" 105 12'36" 105 10'48" 105 21'36"

EXPLANATION

Study area

Subbasins

Drainage

Roads

Subbasin code

Population centers

Nitrate plus nitrite as

 nitrogen in ground

 water, fall 1999, 

 in mg/L

0

0 0.5 1 1.5 2 2.5 3 KILOMETERS

0.5 1 1.5 2 2.5 3 MILES

Nitrate plus nitrite as

 nitrogen in ground

 water, fall 1999, 

 in mg/L

Less than or equal to 1

Greater than 1 and less

 than or equal to 10

Greater than 10

Less than or equal to 1

Greater than 1 

Base modified from U.S. Geological Survey

digital data for 1:24,000 maps

* *

*

* Value greater than 10

 during other sampling 

 times

Figure 34. Concentrations of nitrate plus nitrite in ground- and surface-water sample.
74 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

The tritium samples collected in 24 selected 

wells in the Turkey Creek watershed (table 10) 

had concentrations that ranged from 2.3 to 33.2 TU. 

The median concentration was 13.3 TU. Two samples 

had tritium concentrations less than 5 TU, indicating 

water that has a component of pre-bomb recharge. 

Three sample concentrations were greater than 

20 TU, indicating water with a component of recharge 

from the nuclear bomb testing era (1960’s). These 

tritium results indicate that some water in the Turkey 

Creek watershed was recharged 30 to 40 years ago 

or longer. Most of the remaining samples (about 

80 percent) are probably indicative of more recent 

recharge or some indeterminate mixture containing 

various amounts of pre-bomb, bomb era, and recent 

recharge.

Chloride to Bromide Ratios

The April 2001 samples collected in 23 selected 

wells in the Turkey Creek watershed (table 10) were 

analyzed for bromide concentration in order to compute 

chloride to bromide ratios (Cl/Br). Chloride to bromide 

ratios can be used to distinguish sources of chloride in 

water. Both ions are considered to be mostly conservative during transport. Seawater and precipitation near 

coastal areas have a Cl/Br ratio of about 290, and 

precipitation in the Turkey Creek watershed probably 

has a Cl/Br ratio in the range of 40 to 75 (Davis and 

others, 2001). 

Sources of bromide such as ethylene dibromide 

from historical use as a gasoline antiknock compound 

and from bromine-rich pesticides can cause ratios in

Parmalee Gulch

S. T urkey Creek

N. Turkey Cr

Giant Gulch

Turk ey Cre ek Iowa Gulch

Lone Pine

Estates

Wild Rose Grange

Marshdale

Tiny Town

Indian

Hills

Fenders

Phillipsburg

Homewood Park

Oehlmann

Park

Conifer

8

To Morrison

C470

Shadow Mountain Road

N. Turkey Cree k Rd

Parma lee Gulch

Road

285

285

Marshdale

M

M

D A

B

E

D C

F

L

M

H

P

G

I

J

K

N

O

39 32'24"

39 30'36"

39 34'12"

39 36'

39 37'48"

105 23'24" 105 19'48" 105 18' 105 16'12" 105 14'24" 105 12'36" 105 10'48" 105 21'36"

EXPLANATION

Study area

Subbasins

Drainage

Roads

Subbasin code

Population centers

0

0 0.5 1 1.5 2 2.5 3 KILOMETERS

0.5 1 1.5 2 2.5 3 MILES

Boron in surface

 water, fall 1998, in

 μg/L

Boron in ground

 water, fall 1998, in

 μg/L

<7–15 

16–40

41–105

<7–10

11–40

41–139

Base modified from U.S. Geological Survey

digital data for 1:24,000 maps

Figure 35. Concentrations of boron in ground- and surface-water samples.
HYDROLOGIC CONDITIONS 75

some hydrologic settings to be lower than in precipitation. Fractionation during crystallization of salt from 

solution lowers relative bromide content, causing high 

Cl/Br ratios (Ohio road salt Cl/Br = 8,000; Knuth and 

others, 1990). In water influenced by dissolution of 

evaporites, application of road salt, or treated sewage 

effluent, Cl/Br ratios are higher than 300 due to the 

addition of chloride from salt that is impoverished in 

associated bromide. Some studies have suggested that 

domestic wastewater, which includes ISDS effluent, 

has a Cl/Br ratio between 300 and 600 and road-saltaffected water a Cl/Br ratio between 1,000 and 10,000 

(Vengosh and Pankratov, 1998; Davis and others, 

1998; and Risch and Robinson, 2000); however, 

Granato and Smith (2000) documented treated sewage 

effluent with Cl/Br ratios greater than 2,000, a level 

that overlaps into reported ranges for road salt and 

introduces uncertainty in making distinctions between 

road salt and ISDS influence.

Turkey Creek watershed Cl/Br ratios ranged 

from 15 to 3,535 in ground water (median 192). Three 

ground-water samples had Cl/Br ratios less than 80, 

indicating Cl/Br ratios influenced by precipitation. Of 

the three, one had a ratio of 15, indicating a possible 

source of bromide. Surface-water Cl/Br ratios ranged 

from 310 to 1,971 (median 919). Chloride/bromide 

ratio was poorly correlated to chloride (r2

 = 0.05), 

nitrate plus nitrite (r2

 = 0.03), and tritium (r2 = 0.16) 

concentration. Nine of the ground-water samples 

and all three surface-water samples had Cl/Br ratios 

greater than 300, indicating an influence from a source 

of halite dissolution such as road salt or ISDS effluent, 

or both. Without additional data that document Cl/Br 

ratios in ISDS effluent within the Turkey Creek watershed as unique and distinct from ratios resulting from 

road salt and other deicers/dust inhibitors (which are 

increasing in usage) used on roads, determining the 

precise source is not possible; however, Cl/Br ratios 

clearly indicate that surface water and most ground 

water sampled in the Turkey Creek watershed are 

affected by anthropogenic sources of chloride.

Wastewater Compounds

Samples analyzed for wastewater compounds 

were collected in ground water and surface water 

to evaluate whether sources of human wastewater 

contaminants such as ISDS’s could be affecting water 

quality. The types of wastewater compounds reported 

by the method include selected hormones, pesticides, 

fragrances and flavorings, flame retardants, fecal indicators, petroleum products, combustion products, 

nonionic detergent metabolites, food preservatives, 

and solvents. The analytical identification of these 

compounds is still being refined, and analytical recoveries of some compounds are poor (Steven Zaugg, 

U.S. Geological Survey National Water Quality 

Laboratory, oral commun., November 2001). Concentrations that are identified by the analyst but are less 

than the method reporting limit are reported as estimated. Compounds with poor analytical recoveries 

also are considered estimated. Contamination during 

sample collection and analysis is a risk, and little 

is known about the fate and transport of wastewater 

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 1

1,000

2

5

10

20

50

100

200

500

TRITIUM CONCENTRATION, IN TRITIUM UNITS

(23)

1

1,000

2

3

4

5

7

10

20

30

40

50

70

100

200

300

400

500

700

TRITIUM CONCENTRATION, IN TRITIUM UNITS 

EXPLANATION

Minimum value

25th percentile

Median

75th percentile

Maximum value

(23) Number of observations

Turkey Creek ground-water

 samples 

Turkey Creek watershed.

Data interpolated using

computer program

from Michel (1989)

Data post-1987 from

Albuquerque, New Mexico

Figure 36. Plot of tritium concentrations in precipitation interpolated to Turkey Creek watershed location and decayed to 

year 2000 values, and boxplot of tritium concentrations in selected water wells in the Turkey Creek watershed.
76 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

compounds in the subsurface. Samples were collected in April 2001 (eight ground-water samples, 

four surface-water samples, and two field blanks) 

and September 2001 (three surface-water samples, 

one field blank). No samples of ISDS effluent were 

collected; however, the compounds reported by the 

method are known to occur in human wastewater 

effluent.

On the basis of concentrations reported in estimated ranges, April 2001 results from three of four 

surface-water samples indicated the presence of at least 

one wastewater compound, and results from two of 

eight ground-water samples indicated the presence of 

wastewater compounds (table 10). In September 2001, 

two of three surface-water samples had estimated 

concentrations. The compounds reported in analyses 

were cholesterol, beta-sitosterol, tributylphosphate, 

ethanol 2-butoxy-phosphate, skatol, phenol, tetrachloroethylene, bisphenol A, prometon, N,N-diethyltoluamide 

(DEET), benzophenone, tri(2-chloroethyl)phosphate, 

acetyl-hexamethyl-tetrahydro-naphthale (AHTN), and 

hexahydrohexamethyl-cyclopentabenzopyran (HHCB).

The sample results indicate that some wastewater 

compounds were present both in ground water and 

surface water in the Turkey Creek watershed. However, 

no more than a few compounds were present in any one 

particular sample (highest number of detections in a 

sample was five), little consistency among compounds 

detected was observed, and when detected, compounds 

generally were reported in trace amounts (most 

concentrations were estimated). Although the number 

of samples was small, the frequency of detections was 

higher among surface-water samples than ground-water 

samples. 

Chloride Sources

Chloride is a conservative anion present in trace 

amounts in precipitation. In watersheds such as Turkey 

Creek, rock weathering contributes negligible chloride 

to ground water because of a lack of chloride-bearing 

minerals in bedrock and soil materials. In these watersheds, the sources of chloride other than precipitation 

are anthropogenic, such as ISDS’s and the application 

of salt and dust inhibitors to roads. 

Assuming that chloride is conservatively transported through the watershed, that the concentration of 

chloride in precipitation and the amount of precipitation 

is known, and that evapotranspiration can be measured 

or estimated, a variant of the method described in 

Claassen and Halm (1996) can be used to estimate the 

expected base-flow (or ground-water) concentration of 

chloride in the watershed. For the Turkey Creek watershed, a conservative estimate of chloride concentration 

in base flow was made by assuming that evapotranspiration was 90 percent of watershed mean precipitation and 

concentration of chloride in precipitation was about 

0.09 mg/L (mean of the precipitation-weighted means 

over the period of record for five Colorado Front Range 

National Atmospheric Deposition Program stations 

[U.S. Geological Survey, 2001]). On the basis of these 

assumptions, a chloride concentration for ground water 

of about 0.9 mg/L was calculated. At the mouth of the 

canyon in September 1998 (at near base-flow conditions), chloride concentration in Turkey Creek was 

127 mg/L. It is therefore unlikely that precipitation 

is the only source of chloride to the watershed. The 

median chloride concentration in ground water was 

about 6.8 mg/L, and the median concentration in 

surface water was 64 mg/L. This difference indicates 

that chloride may be transported preferentially along 

flow paths connected to surface water rather than flow 

paths connected to wells. 

Salt applied to roads is one likely source of 

chloride enrichment in the watershed. The Colorado 

Department of Transportation applied an estimated 

mean of 250 tons of salt per year in the form of sand 

and salt mixture to U.S. Highway 285 from 1988 to 

2000 (Chuck Loerwald, Colorado Department of 

Transportation, written commun., August 2000). 

Other unestimated sources of chloride are salt and 

magnesium chloride applied to roads and driveways 

by Jefferson County and private landowners. Known 

loads of chloride in road salt were compared to estimated loads of chloride transported in Turkey Creek 

at the mouth of the canyon. Using a natural log regression of flow and specific conductance and then linear 

regression of chloride to specific conductance resulted 

in estimates of chloride load (tons) and flow-weightedmean concentrations in milligrams per liter for water 

years 1999 through 2001 as follows: 1999 = 400 tons, 

36 mg/L; 2000 = 169 tons, 51 mg/L; 2001 = 168 tons, 

52 mg/L. These estimates show that in 2000 and 2001 

the chloride load is in the same range as a mean mass 

of chloride in road salt applied to U.S. Highway 285. 

In 1999, a high-flow year, the mean applications of 

road salt do not account for all the estimated chloride 

transported out of the watershed. Other sources of 

chloride such as ISDS’s may be another cause of high 

chloride in streams. An unanswered question is why 

high concentrations of chloride found in surface-water 

base flow are rarely seen in the domestic wells 

sampled in the watershed.
HYDROLOGIC CONDITIONS 77

Seasonality of Specific Conductance

Seasonality of specific-conductance measurements in water wells and in streams could indicate 

source-water dynamics through the annual cycle 

and provide information about interactions between 

ground water and surface water. To assess seasonality 

of changes in specific conductance, additional nonUSGS data were available for analysis. Samples for 

analysis of specific conductance were collected weekly 

by homeowners at 24 wells (24 wells in August through 

October 2000 [fall measurement] and 23 of the original 

24 wells in March through June 2001 [spring measurement]) (23l wells listed in table 8 and locations shown 

in fig. 12 except GWB03, which is an undocumented 

location). Specific conductance was then measured by 

Jefferson County Health Department personnel who 

picked up the samples from the homeowners. Measurements of specific conductance in surface water were 

available from USGS measurements associated with 

gaging stations (approximately monthly, 1998–2001), 

from USGS measurements made during quarterly 

samples collected for this study (four values, 1998–99), 

and from data collected during monitoring of the reconstruction of U.S. Highway 285 through the Turkey Creek 

watershed (monthly, 1995–2000; data from Timothy D. 

Steele, Colorado Department of Transportation 

consultant, written commun., October, 2001).

Weekly specific-conductance measurements of 

samples from the 24 wells with both spring and fall 

measurements are plotted along with the following 

hydrologic variables: estimated watershed daily mean 

snowpack and precipitation, daily mean streamflow at 

Turkey Creek at mouth, and monthly water levels in two 

monitoring wells (MH2 and MH11) in figure 37. During 

the fall measurement period, samples from most wells 

showed little change in specific conductance. Samples 

from a few wells showed relatively minor increases and 

decreases in specific conductance by the end of August 

or early September. The changes were generally less 

than 25 percent, although samples from GWH03 had a 

relatively large decrease in specific conductance (from 

538 to 358 μS/cm) and samples from GWO02 had a 

relatively large increase in specific conductance (from 

214 to 430 μS/cm). Samples from GWN01 had the 

largest change in specific conductance (a decrease of 

46 percent of the fall median value), but that change 

is a result of a single anomalous measurement. 

During the spring measurement period, generally minor changes in specific conductance also 

were measured; however, the results of the spring 

measurements showed greater variability than the 

fall measurements. Samples from six wells had 

changes during the spring measurement period that 

were larger than 50 percent of their spring period 

median, and samples from five of those wells 

(GWB03, GWF10, GWH03, GWO10, GWO12) 

showed a decrease in specific conductance during the 

spring melt. One of the largest changes (103 percent of 

the spring median), however, was in samples from 

well GWO02, which showed an increase in specific 

conductance from 367 to 943 μS/cm during the spring 

melt. A seasonality of specific conductance in ground 

water could indicate dilute recharge, in response to 

precipitation, is entering the flow system connected to 

a well. The expected response is related to increases in 

water level in the well, such as that observed in several 

wells noted above. Samples from the well that showed 

increases in specific conductance during spring and 

fall (GWO02) may be the result of recharge even if the 

pattern does not fit the conceptual model of dilution. 

If seasonal recharge was rich in dissolved salt from 

road salt or other sources, an increase in specific 

conductance during the spring melt might result. 

However, because only two samples were collected 

at the GWO02 well for major ions, and neither sample 

was collected during spring melt, additional information is not available to verify the hypothesis that road 

salt is affecting the specific conductance in GWO10. 

Also, GWO02 had the lowest tritium concentration 

sampled, indicating a relatively large component of 

pre-bomb recharge. The majority of wells showed 

minor seasonal changes in specific conductance, 

providing little evidence that recently recharged 

(dilute) water was present, despite water-level fluctuations throughout the watershed that indicated seasonal 

influences on the depth of the water table. 

Instantaneous specific-conductance measurements made in Turkey Creek (stations 06710992 and 

06710995) (fig. 38) (data from USGS and Timothy D. 

Steele, Colorado Department of Transportation 

consultant, written commun., October 2001) and 

its tributaries indicate that specific conductance is 

inversely proportional to streamflow, and decreases in 

specific conductance occur during a spring high-flow 

period, responding to runoff of relatively dilute water. 

Base-flow specific-conductance values were high (more 

than 600 μS/cm) compared to specific conductance in 

ground water (median 313 μS/cm, table 19). In fact, the 

highest specific-conductance value measured in Turkey 

Creek at the mouth (796 μS/cm) was greater than the 

96th percentile of ground-water samples. Even at high 

streamflow, specific conductance in Turkey Creek was
78 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

not observed at levels much below 200 μS/cm, indicating a fairly strong dissolved-solids signal for a mountainous, crystalline rock, hydrogeologic setting.

There are six watersheds that have components 

of similar crystalline bedrock geology, contain similar 

elevation ranges as the Turkey Creek watershed, 

and have NWIS streamflow and specific-conductance 

data from sites along the eastern slope of the Rocky 

Mountains in Colorado. Detailed demographic data 

are not available for these sites, but in general they 

are less developed, in terms of population, than the 

Turkey Creek watershed. Site locations (A–G) are 

shown in figure 1 and summaries of specific-conductance data are listed in table 21. Although the Turkey 

Creek seasonal variation in specific conductance 

has a range as a percentage of median that is similar 

to comparison sites (B–G in table 21), specificconductance values are generally substantially higher 

than comparison sites (fig. 39). This indicates that 

water exiting the Turkey Creek watershed is more 

concentrated than water from the selected comparison 

sites in similar hydrologic settings.

The flow-weighted-mean specific conductance 

(FWMSC) computed from daily values predicted from 

a regression with streamflow is about 290 μS/cm 

(period of 1999–2001 data for station 06710995), a 

value that represents the central tendency of specific 

conductance by streamflow volume, not time. If probable measurement and computational uncertainties are 

considered, the FWMSC is similar to median groundwater specific conductance. 

0

1.0

0.5

0

100

50

0

1

40

100

60

80

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

AT 25 DEGREES CELSIUS

EXPLANATION

GWK04

GWJ02

GWJ01

0

400

200

EXPLANATION

GWB03

GWA01

GWF15

200

400

300

EXPLANATION

GWP04

GWD04

GWN01

200

400

300

EXPLANATION

GWF11

GWG01

GWB02

J F MAMJ J A S O ND JF MAMJ J AS

2000 2001

5

25

10

15

20

DEPTH TO WATER,

IN FEET BELOW

LAND SURFACE

STREAMFLOW,

IN CUBIC FEET

PER SECOND

SNOWPACK

WATEREQUIVALENT,

IN INCHES

PRECIPITATION,

IN INCHES

Monitoring well MH2

Monitoring well MH11

Turkey Creek at mouth (06710995)

Watershed average precipitation

Watershed average

Figure 37. Time-series plot of Turkey Creek watershed hydrologic variables and seasonal specific-conductance 

measurements collected at selected wells in fall 2000 and spring 2001.
ASSESSMENT OF WATER RESOURCES 79

ASSESSMENT OF WATER RESOURCES

An assessment of the water resources in the 

Turkey Creek watershed is presented in this section. 

Much of the assessment is based on the hydrologic 

conditions described in the preceding sections and 

a characterization of many of those conditions in a 

watershed model. The watershed model characterization permits quantified estimates of hydrologic conditions in time and space. The watershed model 

characterization provides simulated estimates for 

water-balance terms such as precipitation, evapotranspiration, soil moisture, overland flow, interflow, and 

base flow, as well as the contents of interflow and 

base-flow reservoirs. In addition, the estimates for 

water-balance terms help answer questions about the 

fate of water that percolates below the soil zone, or 

soil-zone reservoir as depicted in figure 13. Although 

the watershed model does not characterize movement 

of water that is not associated with local streamflow, it 

does characterize the amount of water that is lost from 

base-flow reservoirs; the most likely fate of this water 

is underflow that is discharged from the watershed by 

means other than evapotranspiration or streamflow. 

Estimates of Potential Fracture-Network 

Porosity

In order to bracket the potential volume available 

for ground-water storage in the different rock-group 

fracture networks, estimates of potential porosity were 

calculated for each of the fracture-network models or 

realizations generated with software known as FracMan

1.0

0.5

0

5

0

100

50

0

1

0

500

1,000

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER

AT 25 DEGREES CELSIUS

EXPLANATION

GWA02

GWF10

GWO12

400

600

200

EXPLANATION

GWM07

GWH03

GWH01

0

1,000

500

EXPLANATION

GWO10

GWC02

GWO02

0

2,000

1,000

EXPLANATION

GWP05

GWM06

GWJ06

J F MAMJ J A S O ND JF MAMJ J AS

2000 2001

25

10

15

20

DEPTH TO WATER,

IN FEET BELOW

LAND SURFACE

STREAMFLOW,

IN CUBIC FEET

PER SECOND

SNOWPACK

WATEREQUIVALENT,

IN INCHES

PRECIPITATION,

IN INCHES

Monitoring well MH2

Monitoring well MH11

Turkey Creek at mouth (06710995)

Watershed average precipitation

Figure 37. Time-series plot of Turkey Creek watershed hydrologic variables and seasonal specific-conductance 

measurements collected at selected wells in fall 2000 and spring 2001—Continued.
80 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

(Dershowitz and others, 1996) that is briefly described 

in the Appendix. Potential porosity is defined here as a 

measure of fracture porosity based solely on simulation 

of geometric measures from outcrops (for example, 

fracture intensity, trace length). Potential porosity calculations assume that rock groupings, computed fractureset statistics and intensities, reasonable estimates of 

aperture, and the scale of the model domains are all 

representative of near-surface field conditions. Potential 

porosity is not directly linked to hydraulic parameters 

from field measures such as pumping tests or analysis of 

water levels compared with precipitation and discharge 

over time. Rather, potential porosity is simply an estimate based on reasonable values for aperture and 

measured fracture intensities. Use of geometric 

fracture-network measurements to simulate hydraulic 

properties tends to result in overestimation. Simulation 

results, however, are based on measurements in the 

Turkey Creek watershed and provide a reasonable 

set of estimated porosity values for the representative 

rock groups relative to one another. Additionally, as is 

described below, the fracture-network realizations also 

were conditioned by using transmissivities and apertures derived from previously completed aquifer tests 

and the cubic law, respectively (Tomusiak and others, 

2000; Folger, 1995).

Ten calibrated fracture-network realizations were 

constructed with FracMan for the watershed at representative localities. Three realizations represent the 

intrusive rocks, four represent the metamorphic rocks, 

and three realizations represent the fault zones (as in 

Caine and Forster, 1999). Two of the realizations represent faulted metamorphic rock, and one represents 

faulted intrusive rock.

In each realization, the fracture apertures are 

initially set to a constant value and are correlated with 

transmissivity by using the cubic law (for example, 

Snow, 1968):

Streamflow

Specific conductance

1,000

SPECIFIC CONDUCTANCE, IN MICROSIEMENS

PER CENTIMETER AT 25 DEGREES CELSIUS STREAMFLOW, IN CUBIC FEET PER SECOND

800

600

400

200

0

1,000

500

200

100

50

20

10

5

2

1

J FMAMJ J

1998

A S O ND J FMAMJ J

1999

A S O ND J FMAMJ J

2000

SPECIFIC CNDUCTANCE, IN MICROSIEMENS

PER CENTIMETER AT 25 DEGREES CELSIUS

ASON 0

200

400

600

800

1,000

1,200

1,400

1,600

0.5

0.2

0.1

0.05

0.02

0.01

0.01 0.02 0.05 0.1 0.2 0.5 1 2 5

STREAMFLOW, IN CUBIC FEET PER SECOND

10 20 50 100 200 500 1,000

Figure 38. Correlation of specific conductance and streamflow and time-series plot showing seasonal variation 

of specific conductance and streamflow at Turkey Creek at mouth of canyon near Morrison.
ASSESSMENT OF WATER RESOURCES 81

(6)

where

Tf is fracture transmissivity [L2/T],

b is aperture [L],

ρ is the fluid density [M/L3],

g is the acceleration due to gravity [L/T2], and

μ is the dynamic fluid viscosity [M/LT] 

(M = mass, L = length, T = time).

In calculating fracture volume (Vf) and total 

fracture porosity (np), estimates of hydraulic aperture 

(b), fracture intensity (P32), and domain volume (Vm) 

are the only parameters needed. Vf

 and np are calculated using:

(7)

(8)

where

Vf and Vm have the dimensions of [L3], 

b has the dimension of [L], and

P32 has the dimension of [L2/L3]. 

Two end-member cases and one intermediate 

case for constant aperture were used in the porosity 

calculations (1,000 μm [or 1 mm], 100 μm, and 10 μm). 

Although aperture distributions were not recorded in 

the field, except to note if the fractures were less than 

or greater than 1 mm, the chosen end members are 

assumed to be representative of field conditions. Simulations with all fractures having apertures of 1 mm may 

overestimate porosity, whereas simulations with all 

fractures having apertures of 10 μm will likely underestimate porosity. The actual aperture distribution is 

likely between the end-member extremes for nearsurface conditions (about 0 to 300 ft below land 

surface). The aperture estimates were compared to 

calculated hydraulic fracture apertures made by Folger 

(1995) in the intrusive rocks in the vicinity of Conifer, 

Colo. (fig. 1). Folger (1995) used the cubic law to calculate apertures from transmissivity values obtained from 

single-well, short-term aquifer pumping tests. Folger’s 

calculated aperture estimates ranged between 60 and 

570 μm, which is well within the end-member estimates 

for the intrusive rocks (Folger, 1995, table 22). Even if 

these aperture estimates are reasonable, however, there 

is the random possibility that one very large fracture 

(for example, 5 mm) or a network of very small fractures (for example less than 1 μm) could completely 

disrupt porosity estimates. These random fractures 

could dominate the local flow and storage system,

Tf

b

3

12

----- ρg

μ = × ------

Vf b P32 × Vm = ×

np

Vf

Vm

= ------

Table 21. Specific-conductance data summary for Turkey Creek at mouth (site A) and eight comparison sites on the eastern 

slope of the Rocky Mountains in Colorado

[ID, identification number; specific conductance in microsiemens per centimeter at 25 degrees Celsius; drainage area in square miles; range percentage of 

median computed by dividing the difference between maximum and minimum by the median; most measurements collected on monthly basis associated 

with stream-gage operations]

Site 

letter in

fig. 1

USGS

station ID Station name

Latitude

(degrees,

minutes,

seconds)

Longitude

(degrees,

minutes,

seconds)

Drainage

area

Minimum Median Maximum

Range

percentage 

of median

A 06710995 Turkey Creek at mouth of 

canyon near Morrison

39 37 13 105 11 41 47.4 172 454 796 137

B 07099050 Beaver Creek above upper 

Beaver Cemetery near 

Penrose

38 33 42 105 01 17 122 57 88 129 82

C 07105000 Bear Creek near Colorado 

Springs

38 49 21 104 53 17 6.89 70 91 147 85

D 07105490 Cheyenne Creek at Evans 

Ave at Colorado Springs

38 47 26 104 51 49 21.7 68 110 175 97

E 07105945 Rock Creek above Fort 

Carson Reservation

38 42 27 104 50 46 6.79 56 149 240 123

F 07107900 Greenhorn Creek near Rye 37 55 14 104 57 21 9.56 48 85 120 85

G 07108100 Graneros Creek near Rye 37 54 47 104 55 31 4.32 70 160 286 135
82 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

particularly when considering the heterogeneity of the 

fracture-intensity distributions and the realization that 

some near-surface fractures likely close down with 

depth. Regardless, these are reasonable estimates of 

aperture that are translated into potential porosities that 

might exist considering the lack of field observations 

and measurements of fracture-network properties with 

depth.

Figure 40 and table 23 are a compilation of 

the estimated fracture intensities and total potential 

porosities for each fracture-network realization 

using the end-member apertures. Calculated porosity 

estimates are shown for each lithology and their faulted 

equivalents (table 23). Although the calculated fractureporosity values range over 4 orders of magnitude 

(from 0.0016 to 2.78 percent), the midrange (100 μm) 

constant aperture simulations produce porosity values 

from 0.016 percent to 0.051 percent for the nonfaultzone realizations and of approximately 0.27 percent for 

the fault-zone realizations (table 23). The intrusive-rock 

porosity shows little variation and ranges from 0.020 to

(31) (16) (125) (127) (223) (22) (43)

A B C D E F G

SITE

900

0

100

200

300

400

500

600

700

800

SPECIFIC CONDUCTANCE, IN MICROSIEMENS PER CENTIMETER AT 25 DEGREES CELSIUS

EXPLANATION

Minimum value

25th percentile

Median

75th percentile

Maximum value

(31) Number of observations

Specific conductance 

Figure 39. Boxplot showing distribution of specific conductance at Turkey Creek at mouth of canyon (site A) and six 

comparison sites.

Table 22. Turkey Creek watershed hydrologic parameter 

estimates from previous work (Folger, 1995)

[m2/s, square meters per second; μm, micrometers;

 %, percentage; max, maximum; min, minimum]

--------------------------------------------------------

 Hydraulic 

Estimated aperture Porosity 

transmissivities estimates estimates 

 (m2/s) (μm) (%)

--------------------------------------------------------

0.0000347 380 0.019 

0.0000694 240 0.012 

0.000127 110 0.006 

0.0000347 200 0.001 

0.000000810 190 0.057 

0.0000104 120 0.036 

0.00139 60 0.016 

0.00000231 100 0.003 

0.00000463 570 

0.00000926 360 0.057 max 

0.0000231 160 0.001 min 

0.0000810 300 

0.000162 

0.000174 570 max 

0.000139 60 min 

0.0000116 

0.00185 

0.00000810 

0.00000579 

 

0.00185 max 

0.000000810 min 

--------------------------------------------------------
ASSESSMENT OF WATER RESOURCES 83

0.025 percent, whereas the metamorphic-rock porosity 

shows slightly greater variation ranging from 0.016 to 

0.051 for the 100-μm constant aperture simulations 

(fig. 40 and table 23). The fault-zone porosity values are 

relatively uniform within a single fault zone and from 

one fault zone to another, and the fault-zone porosity 

values are consistently one order of magnitude greater 

than the nonfault-zone porosity values. The calculated 

porosity values are well within the general values of 

porosity reported for crystalline rocks (Freeze and 

Cherry, 1979) and also within values estimated by 

Folger (1995).

In the Turkey Creek watershed, fracture porosity 

is a critical factor limiting water availability because it 

is, in general, extremely low. The estimated potential 

porosities for the rock groups are, on average, roughly 

two to three orders of magnitude lower than those in 

sedimentary rocks that typically have porosities of 5 

to 25 percent (Freeze and Cherry, 1979). The actual 

amount of available ground water is a function of 

the distribution of porosity and other factors such as 

recharge and discharge rates from natural and human 

causes, saturated thickness, and the circulation depth 

of ground-water flow. 

Runoff Modeling

The watershed characterization presented in 

this section helps address some of the issues stated 

in the preceding “Estimates of Potential FractureNetwork Porosity” section. The simulated results 

provide temporal and spatial estimates of recharge. 

The simulations also provide estimates of how much and 

how quickly recharge leaves the watershed as interflow 

and base flow and how much of the recharge percolates 

to deeper parts of the watershed and is not associated 

with local streamflow. Estimates for terms presented in 

this section can be compared to estimates of contemporary (2001) withdrawals made by domestic wells.

Hydrologic Response Unit Delineation and 

Parameterization

Hydrologic Response Units (HRU’s) were 

delineated to provide a topography-based accounting 

framework for surface, or near-surface, processes 

related to evapotranspiration, soil moisture, snowpack, 

and percolation to deeper parts of the watershed 

system. All of these processes, to some extent, are 

influenced by topographic characteristics such as 

aspect and slope. As indicated in the “Runoff 

Modeling Methods” section, automated methods 

were used to delineate HRU’s in the Turkey Creek 

watershed. The methods implement a series of algorithms that have been developed to work with digital 

elevation model (DEM) data to define surfaces and 

their topographic characteristics within the watershed 

that border streams and conform to the watershed 

boundary (Jensen and Domingue, 1988). The number 

of HRU’s can be controlled to obtain a user-defined, 

acceptable level of resolution with respect to topographic features. The watershed was subdivided so 

that, on an HRU basis, values for slope and aspect 

were relatively representative of aspects for all points 

within the HRU. The result was 112 HRU’s with a 

mean area of 270.7 acres (fig. 41, table 24).

–5

–4

–3

–2

–1

HARRINGTON NOBEL GREEN 285S LEGAULT PEAK US40 G1 US40 G2 C73

 = 21.00

LOG POTENTIAL POROSITY

Intrusive rocks Metamorphic rocks

285N LAMBERT

Fault-zone localities

ρ =

b = 10 microns

b = 100 microns

b = 1 mm

2.46 ρ = 2.01 ρ = 2.35 ρ = 5.01 ρ = 1.61 ρ = 4.52 ρ = 2.31 ρ = 27.78 ρ = 27.17 ρ

Figure 40. Plot of the log of total fracture model potential porosity for each locality (ρ = fracture intensity).
84 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

Table 23. Turkey Creek watershed fracture-model potential porosity results

[Vf = total fracture volume in cubic meters; np = total fracture porosity in model 

 in percent; m2/m3, square meter per cubic meter; m3, cubic meter, μm, micrometer 

 MAX, maximum; MIN, minimum] 

---------------------------------------------------------------------------------------

 Model

Location fracture Model 

and model density volume Vf Vf Vf np np np

size (m2/m3) (m3) 10μm 100μm 1mm 10μm 100μm 1mm 

---------------------------------------------------------------------------------------

 METAMORPHIC ROCKS

285South 

 2 m 5.10 8 0.000408 0.00408 0.0408 0.0051 0.051 0.51

 5 m 5.10 125 0.00638 0.0638 0.638 

10 m 5.10 1000 0.0510 0.510 5.10 

15 m 5.10 3375 0.172 1.72 17.2 

 

285North 

 2 m 1.607 8 0.000129 0.00129 0.0129 0.0016 0.0161 0.1607

 5 m 1.607 125 0.00201 0.0201 0.201 

10 m 1.607 1000 0.0161 0.161 1.61 

15 m 1.607 3375 0.0542 0.542 5.42 

 

LAMBERT 

 2 m 4.517 8 0.000361 0.00361 0.0361 0.0045 0.0452 0.4517

 5 m 4.517 125 0.00565 0.0565 0.565 

10 m 4.517 1000 0.0452 0.452 4.52 

15 m 4.517 3375 0.152 1.52 15.2 

 

LEGAULT PEAK 

 2 m 2.31 8 0.000185 0.00185 0.0185 0.0023 0.0231 0.231

 5 m 2.31 125 0.00289 0.0289 0.289 

10 m 2.31 1000 0.0231 0.231 2.31 

15 m 2.31 3375 0.0780 0.780 7.80

 AVERAGE 0.0034 0.0338 0.3384

 MAX 0.0051 0.051 0.51

 MIN 0.0016 0.0161 0.1607

 INTRUSIVE ROCKS

HARRINGTON 

 2 m 2.46 8 0.000197 0.00197 0.0197 0.0025 0.0246 0.246

 5 m 2.46 125 0.00308 0.0308 0.308 

10 m 2.46 1000 0.0246 0.246 2.46 

15 m 2.46 3375 0.0830 0.830 8.30 

 

NOBEL 

 2 m 2.01 8 0.000161 0.00161 0.0161 0.0020 0.0201 0.201

 5 m 2.01 125 0.00251 0.0251 0.251 

10 m 2.01 1000 0.0201 0.201 2.01 

15 m 2.01 3375 0.0678 0.678 6.78 

 

GREEN 

 2 m 2.35 8 0.000188 0.00188 0.0188 0.0024 0.0235 0.235

 5 m 2.35 125 0.00294 0.0294 0.294 

10 m 2.35 1000 0.0235 0.235 2.35 

15 m 2.35 3375 0.0793 0.793 7.93

 AVERAGE 0.0023 0.0227 0.2273

 MAX 0.0025 0.0246 0.2460

 MIN 0.0020 0.0201 0.2010

 FAULT ZONE ROCKS

 

US40 FAULT ZONE GRID 1 

 2 m 27.78 8 0.00222 0.0222 0.222 0.028 0.278 2.78

 5 m 27.78 125 0.0347 0.347 3.47 

10 m 27.78 1000 0.278 2.78 27.8 

15 m 27.78 3375 0.938 9.38 93.8 

 

US40 FAULT ZONE GRID 2 

 2 m 27.17 8 0.00217 0.0217 0.217 0.027 0.272 2.72

 5 m 27.17 125 0.0340 0.340 3.40 

10 m 27.17 1000 0.272 2.72 27.2 

15 m 27.17 3375 0.917 9.17 91.7 

 

C73 FAULT ZONE 

 2 m 21.00 8 0.00168 0.0168 0.168 0.021 0.210 2.10

 5 m 21.00 125 0.0263 0.263 2.63 

10 m 21.00 1000 0.210 2.10 21.0 

15 m 21.00 3375 0.709 7.09 70.9

 AVERAGE 0.0253 0.253 2.53

 MAX 0.028 0.278 2.78

 MIN 0.021 0.210 2.10

---------------------------------------------------------------------------------------
ASSESSMENT OF WATER RESOURCES 85

Precipitation-Runoff Modeling System (PRMS) 

input parameters related to soil characteristics were 

determined by using digital data available from the 

Soil Survey Geographic data base (SSURGO) 

(U.S. Department of Agriculture, 1995) and a local 

implementation (Viger, 1998) of algorithms developed 

by Wolock (1997). The algorithms assign values to 

PRMS input parameters related to soil properties such 

as thickness and water-holding capacities. 

PRMS input parameters associated with 

vegetation were defined in terms of type and density 

(table 24). Vegetation types were defined as trees and 

grasses, and densities were determined using digital 

orthophoto imagery provided by Jefferson County. 

The original imagery, which has a grid resolution 

of 15 ft, was reclassified to a grid that matches the 

DEM (98.4 ft) and has values for percentage of trees 

(R.M.T. Webb, U.S. Geological Survey, oral commun., 

2001). Additional PRMS input parameters associated 

with vegetation such as seasonal interception rates 

were provided from other calibrations of PRMS in the 

mountainous areas of Colorado, as part of the methods 

implemented by Viger (1998).

Most of the remaining PRMS input parameters 

are related to processes describing movement of water 

from one part of the system to another (such as percolation from the soil zone to deeper parts of the watershed 

system), energy-budget processes that are related to 

evapotranspiration, precipitation phase assignment, or 

snowpack melt and accumulation. Initial values for input 

parameters associated with climatic processes also were 

obtained from other calibrations of PRMS in the mountainous areas of Colorado, as part of the methods implemented by Viger (1998).

Parmalee Gulch

S. Turkey Creek

N. Turkey Cr

Giant Gulch

Turkey Creek Iowa Gulch

Lone Pine

Estates

Wild Rose Grange

Marshdale

Tiny Town

Indian

Hills

Fenders

Phillipsburg

Homewood Park

Oehlmann

Park

Conifer

8

To Morrison

C470

Shadow Mountain Road

N. Turkey Creek Rd

Parma lee Gulch

Road

285

285

Marshdale

39°32'24"

39°30'36"

39°34'12"

39°36'

39°37'48"

105°23'24" 105 105°21'36" °19'48" 105°18' 105°16'12" 105°14'24" 105°12'36" 105°10'48"

EXPLANATION

Study area

Hydrologic Response

 Unit and identifi-

 cation number

Drainage

Roads

Population centers

0

0 0.5 1 1.5 2 2.5 3 KILOMETERS

0.5 1 1.5 2 2.5 3 MILES

1

6

2

28

86

41

44

42

66

21

25

59

19

45 48

15

43

56 52

12

47

4

18

89

74

20

46

3 5

32

13

9

67

107

26

35

68

7

94

58

80

81

78

61

16

104

8

22

65

93

34

108

24

64

96

29

29

90

51

87

33

57

49

102

31

14

73

36

54

55

91

84

82 95

106

39

23

85

110

92

17

76

30

69

111

62

112

11

60

77

97

10

27

101

71

37

98

99

40

70

88

53

105

50

63

79

72

83

38

75

100

103

109

Base modified from U.S. Geological Survey

digital data for 1:24,000 maps

Figure 41. Hydrologic Response Units delineated for use with the Precipitation-Runoff Modeling System in the Turkey 

Creek watershed.
86 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

Table 24. Summary of Hydrologic Response Unit and base-flow reservoir characteristics, and hydrologic response unit accounting 

for contemporary simulation in the Turkey Creek watershed

[Period, period summarized is water year except for 1999, which is January through September; HRU, hydrologic response unit shown in figure

 42; cd, cover density, percentage of HRU that is treed; area, HRU or interflow/base-flow reservoir area in acres; elv, elevation in feet above

 NGVD29 for centroid of HRU; rp, radiation plane - one of 28 unique planes developed for Turkey Creek watershed; asp, aspect of radiation 

 plane in compass degrees; sl, slope of radiation plane; slope, mean slope of HRU; rf, index of precipitation station, shown in table 2 and

 figure 7, associated with HRU; ss-gw,index of interflow and base-flow reservoir (1 = metamorphic, 2 = intrusive, 3 = fault zone, 4 = Pikes Peak

 Granite); smax, maximum available soil moisture in inches; tet, total evapotranspiration in inches; ovf, overland flow in inches; rsd, residual

 between HRU precipitation and tet; rcb, base-flow routing coefficient; gsnk, base-flow reservoir seepage coefficient]

--------------------------------------------------------------------------------------------------------------------------------------------

 HRU summary

--------------------------------------------------------------------------------------------------------------------------------------------

 Period

 --------------------------------------------------------------------

 HRU Characteristics 1999 2000 2001

---------------------------------------------------------------------- -------------------- --------------------- ---------------------

HRU cd area elv rp asp sl slope rf ss-gw smax tet ovf rsd tet ovf rsd tet ovf rsd 

--------------------------------------------------------------------------------------------------------------------------------------------

 1 0.28 758.69 7367 7 225 0.15 0.130 8 1 4.37 15.41 0.14 5.81 17.36 0.06 -0.22 19.60 0.08 -0.72

 2 0.38 562.90 7241 8 135 0.25 0.270 8 1 5.21 16.37 0.15 4.84 17.52 0.06 -0.38 19.53 0.08 -0.65

 3 0.61 182.07 8066 20 45 0.35 0.310 8 2 2.33 13.04 0.07 8.25 15.00 0.04 2.16 16.56 0.04 2.36

 4 0.46 197.82 7339 13 45 0.15 0.190 8 1 5.98 16.63 0.13 4.60 17.48 0.06 -0.34 19.54 0.08 -0.66

 5 0.31 179.85 7327 5 90 0.15 0.220 8 1 3.16 13.81 0.11 7.44 17.01 0.05 0.14 19.14 0.06 -0.24

 6 0.18 658.48 7018 27 180 0.45 0.390 8 1 2.68 13.91 0.12 7.33 17.19 0.06 -0.05 18.83 0.07 0.06

 7 0.46 133.73 7925 26 90 0.35 0.300 8 2 2.08 13.08 0.08 8.20 16.34 0.05 0.81 18.53 0.05 0.38

 8 0.29 122.98 8241 5 90 0.15 0.140 8 1 3.13 14.16 0.09 7.11 16.97 0.05 0.18 19.10 0.06 -0.20

 9 0.51 157.99 7203 5 90 0.15 0.230 8 1 5.77 16.53 0.12 4.71 17.55 0.06 -0.41 19.56 0.08 -0.68

 10 0.92 115.76 7654 20 45 0.35 0.320 8 2 0.80 10.76 0.06 10.54 13.10 0.03 4.07 14.20 0.04 4.72

 11 0.19 122.06 7948 4 135 0.15 0.150 8 1 2.21 12.83 0.09 8.44 16.33 0.05 0.82 18.34 0.06 0.56

 12 0.66 431.39 7302 13 45 0.15 0.260 8 1 5.39 16.31 0.11 4.94 17.46 0.06 -0.32 19.59 0.07 -0.70

 13 0.65 343.96 7588 16 180 0.35 0.310 8 1 1.96 12.97 0.08 8.31 17.07 0.04 0.09 18.63 0.05 0.28

 14 0.18 167.63 7769 7 225 0.15 0.130 8 1 6.79 16.90 0.19 4.27 17.53 0.07 -0.40 19.35 0.09 -0.48

 15 0.41 517.15 6942 28 0 0.65 0.530 8 1 2.49 12.35 0.08 8.93 11.47 0.05 5.68 13.17 0.06 5.73

 16 0.75 249.13 7783 17 45 0.25 0.240 8 2 1.67 12.64 0.07 8.65 14.68 0.04 2.48 16.19 0.04 2.73

 17 0.41 136.14 7919 23 0 0.15 0.120 8 1 3.92 14.93 0.09 6.34 16.56 0.05 0.59 18.09 0.06 0.81

 18 0.27 386.38 7817 5 90 0.15 0.170 8 1 4.98 16.12 0.11 5.13 17.36 0.06 -0.22 19.62 0.07 -0.73

 19 0.50 601.98 7128 20 45 0.35 0.290 8 1 3.47 14.09 0.09 7.18 16.36 0.05 0.79 18.03 0.07 0.86

 20 0.48 365.82 7800 10 225 0.25 0.190 8 2 6.57 16.42 0.14 4.80 17.57 0.07 -0.43 19.75 0.09 -0.88

 21 0.30 669.03 7217 15 225 0.35 0.340 8 1 2.86 14.21 0.12 7.03 17.43 0.06 -0.29 19.34 0.06 -0.44

 22 0.32 239.68 7547 7 225 0.15 0.220 8 1 5.07 16.26 0.15 4.95 17.51 0.06 -0.37 19.57 0.07 -0.68

 23 0.49 142.25 7792 25 90 0.25 0.290 8 2 5.85 15.99 0.13 5.24 17.62 0.07 -0.49 19.84 0.08 -0.96

 24 0.25 206.89 7470 13 45 0.15 0.160 8 1 4.60 15.37 0.11 5.88 17.34 0.06 -0.20 19.75 0.07 -0.86

 25 0.23 648.10 7671 5 90 0.15 0.190 4 1 3.36 15.77 0.16 5.98 17.15 0.09 0.14 16.18 0.07 -0.59

 26 0.28 293.21 7318 4 135 0.15 0.260 8 1 6.56 17.08 0.19 4.09 17.69 0.07 -0.56 19.49 0.08 -0.61

 27 0.29 111.69 8012 7 225 0.15 0.310 4 2 3.88 16.63 0.17 5.11 17.45 0.08 -0.15 16.04 0.07 -0.45

 28 0.38 1086.7 7816 3 90 0.05 0.100 4 1 5.17 16.86 0.20 4.85 17.63 0.09 -0.34 15.98 0.07 -0.39

 29 0.22 196.15 7892 3 90 0.05 0.110 4 2 6.22 17.21 0.23 4.47 17.68 0.11 -0.41 15.95 0.07 -0.36

 30 0.36 128.36 7546 4 135 0.15 0.210 4 2 4.20 16.77 0.18 4.96 17.30 0.09 -0.01 16.00 0.07 -0.41

 31 0.27 168.18 7369 4 135 0.15 0.140 4 1 2.09 14.32 0.14 7.45 16.41 0.07 0.90 15.33 0.07 0.26

 32 0.36 353.59 7382 15 225 0.35 0.280 9 1 6.35 17.27 0.17 2.76 15.74 0.06 -0.10 17.66 0.08 -0.88

 33 0.65 188.19 7303 24 0 0.35 0.310 9 1 4.92 15.42 0.10 4.68 15.71 0.06 -0.07 16.94 0.06 -0.14

 34 0.73 224.86 7643 23 0 0.15 0.200 4 2 3.14 15.16 0.12 6.63 16.77 0.07 0.54 15.66 0.05 -0.05

 35 0.64 276.17 7444 22 0 0.25 0.190 4 1 3.87 15.86 0.16 5.89 17.12 0.09 0.17 16.15 0.06 -0.55

 36 0.72 165.59 7181 14 270 0.25 0.240 9 1 5.49 16.34 0.14 3.72 15.76 0.06 -0.12 17.76 0.06 -0.96

 37 0.70 106.50 7318 20 45 0.35 0.270 9 1 4.54 15.47 0.09 4.64 15.70 0.06 -0.06 17.81 0.06 -1.01

 38 0.34 60.569 7046 25 90 0.25 0.210 9 1 4.34 15.64 0.12 4.44 15.53 0.06 0.11 17.74 0.07 -0.95

 39 0.77 142.25 7556 22 0 0.25 0.210 4 2 3.78 15.59 0.14 6.18 17.04 0.08 0.26 15.89 0.06 -0.29

 40 0.78 87.427 7482 17 45 0.25 0.190 4 2 3.73 15.92 0.15 5.84 17.36 0.08 -0.06 16.00 0.06 -0.40

 41 0.44 931.50 7495 5 90 0.15 0.210 4 1 4.56 16.73 0.18 5.00 17.49 0.09 -0.20 15.96 0.06 -0.36

 42 0.68 763.50 7960 23 0 0.15 0.180 4 1 5.04 16.30 0.17 5.44 17.74 0.09 -0.45 15.99 0.06 -0.39

 43 0.72 453.80 7879 20 45 0.35 0.280 4 2 6.01 16.75 0.19 4.97 17.79 0.10 -0.51 15.93 0.07 -0.34

 44 0.66 782.58 8200 9 270 0.15 0.220 4 2 5.58 17.12 0.18 4.61 17.82 0.09 -0.53 16.03 0.06 -0.43

 45 0.48 546.04 7324 14 270 0.25 0.260 9 1 4.97 15.97 0.14 4.09 15.63 0.06 0.01 17.78 0.06 -0.98

 46 0.57 365.45 7428 9 270 0.15 0.190 4 1 4.40 16.47 0.15 5.29 17.64 0.09 -0.35 16.01 0.06 -0.41

 47 0.51 408.42 8041 1 0 0.00 0.220 17 2 5.26 16.69 0.18 5.04 17.87 0.09 -0.38 19.21 0.09 -0.14

 48 0.44 519.19 7298 5 90 0.15 0.180 9 1 4.61 15.72 0.13 4.35 15.58 0.06 0.06 17.80 0.06 -1.00

 49 0.68 180.03 8325 13 45 0.15 0.200 4 2 6.23 16.92 0.21 4.78 17.88 0.10 -0.60 15.99 0.07 -0.40

 50 0.73 76.127 7588 19 315 0.25 0.170 4 2 3.94 16.04 0.15 5.72 17.49 0.08 -0.19 16.04 0.06 -0.44

 51 0.42 192.63 7884 5 90 0.15 0.100 4 1 4.27 16.47 0.17 5.27 17.53 0.09 -0.24 16.00 0.07 -0.41

 52 0.39 443.43 8211 14 270 0.25 0.230 4 1 6.05 17.34 0.21 4.36 17.82 0.09 -0.53 16.05 0.07 -0.46

 53 0.22 79.092 7828 11 315 0.15 0.090 4 1 2.90 14.70 0.13 7.08 16.54 0.07 0.77 15.56 0.06 0.04

 54 0.28 162.99 8097 13 45 0.15 0.120 4 1 4.22 15.91 0.16 5.84 17.53 0.09 -0.24 15.99 0.07 -0.40

 55 0.49 154.10 7978 4 135 0.15 0.110 4 1 4.08 16.68 0.17 5.06 17.50 0.08 -0.20 16.02 0.06 -0.42

 56 0.28 448.24 7531 5 90 0.15 0.200 4 1 3.43 15.89 0.16 5.86 17.15 0.08 0.15 16.19 0.06 -0.59

 57 0.81 180.96 8236 5 90 0.15 0.160 16 2 4.82 17.06 0.12 5.63 20.31 0.08 -0.31 19.58 0.07 -0.10

 58 0.38 261.72 8012 14 270 0.25 0.180 4 1 2.61 15.01 0.12 6.78 16.85 0.08 0.45 15.80 0.06 -0.20

 59 0.34 640.33 8253 4 135 0.15 0.280 4 2 3.89 16.37 0.15 5.39 17.61 0.08 -0.31 16.30 0.06 -0.70

 60 0.55 120.58 8041 23 0 0.15 0.160 4 3 3.67 15.76 0.14 6.01 17.31 0.08 -0.01 16.12 0.06 -0.52

 61 0.35 250.98 8225 6 180 0.15 0.230 4 1 6.53 17.99 0.24 3.68 18.12 0.10 -0.84 16.30 0.07 -0.71

 62 0.52 123.91 8023 25 90 0.25 0.200 4 2 1.88 13.89 0.10 7.92 16.11 0.07 1.20 15.15 0.05 0.46

 63 0.80 73.164 8515 3 90 0.05 0.100 16 1 4.66 16.89 0.12 5.80 20.15 0.08 -0.15 19.45 0.07 0.03

 64 0.80 203.19 8203 13 45 0.15 0.180 16 2 4.60 16.48 0.12 6.21 20.01 0.08 -0.01 18.62 0.07 0.86

 65 0.36 238.38 7788 8 135 0.25 0.180 1 1 4.11 16.42 0.16 4.55 19.12 0.10 -0.24 16.01 0.07 -0.69
ASSESSMENT OF WATER RESOURCES 87

Table 24. Summary of Hydrologic Response Unit and base-flow reservoir characteristics, and hydrologic response unit accounting 

for contemporary simulation in the Turkey Creek watershed—Continued

[Period, period summarized is water year except for 1999, which is January through September; HRU, hydrologic response unit shown in figure

 42; cd, cover density, percentage of HRU that is treed; area, HRU or interflow/base-flow reservoir area in acres; elv, elevation in feet above

 NGVD29 for centroid of HRU; rp, radiation plane - one of 28 unique planes developed for Turkey Creek watershed; asp, aspect of radiation 

 plane in compass degrees; sl, slope of radiation plane; slope, mean slope of HRU; rf, index of precipitation station, shown in table 2 and

 figure 7, associated with HRU; ss-gw,index of interflow and base-flow reservoir (1 = metamorphic, 2 = intrusive, 3 = fault zone, 4 = Pikes Peak

 Granite); smax, maximum available soil moisture in inches; tet, total evapotranspiration in inches; ovf, overland flow in inches; rsd, residual

 between HRU precipitation and tet; rcb, base-flow routing coefficient; gsnk, base-flow reservoir seepage coefficient]

--------------------------------------------------------------------------------------------------------------------------------------------

 HRU summary

--------------------------------------------------------------------------------------------------------------------------------------------

 Period

 --------------------------------------------------------------------

 1999 2000 2001

 -------------------- --------------------- ---------------------

hru cd area elv rp asp sl slope rf ss-gw smax tet ovf rsd tet ovf rsd tet ovf rsd 

--------------------------------------------------------------------------------------------------------------------------------------------

 66 0.51 679.96 7587 23 0 0.15 0.210 1 1 5.13 16.11 0.15 4.87 18.85 0.11 0.02 16.16 0.07 -0.84

 67 0.32 312.29 7559 4 135 0.15 0.220 1 1 6.16 17.23 0.22 3.68 19.22 0.12 -0.36 15.87 0.09 -0.57

 68 0.38 273.39 7968 6 180 0.15 0.180 1 1 3.35 15.54 0.15 5.44 18.69 0.09 0.20 15.82 0.08 -0.51

 69 0.36 126.51 8005 5 90 0.15 0.130 1 1 5.38 16.69 0.16 4.28 19.22 0.12 -0.36 16.07 0.08 -0.76

 70 0.75 85.945 8530 23 0 0.15 0.130 16 1 2.59 14.75 0.07 7.99 17.82 0.07 2.19 16.84 0.05 2.666

 71 0.76 109.28 8757 4 135 0.15 0.130 16 3 4.73 17.02 0.12 5.67 20.18 0.08 -0.18 19.71 0.07 -0.23

 72 0.97 67.607 8913 5 90 0.15 0.190 16 2 3.96 16.42 0.10 6.29 20.21 0.07 -0.20 18.69 0.06 0.80

 73 0.71 166.51 8690 13 45 0.15 0.180 16 2 2.64 14.96 0.09 7.76 18.35 0.07 1.66 17.29 0.05 2.21

 74 0.27 372.12 8210 3 90 0.05 0.140 16 2 3.01 15.99 0.10 6.72 19.79 0.08 0.21 18.89 0.07 0.59

 75 0.67 60.013 9245 25 90 0.25 0.290 16 4 2.14 14.47 0.07 8.27 18.85 0.06 1.17 17.41 0.05 2.09

 76 0.79 132.80 8371 5 90 0.15 0.160 16 1 2.73 15.60 0.09 7.12 19.60 0.07 0.41 18.34 0.06 1.15

 77 0.10 118.91 8156 18 270 0.45 0.330 16 1 0.90 12.35 0.08 10.38 15.92 0.07 4.09 15.89 0.06 3.60

 78 0.16 255.79 8072 4 135 0.15 0.190 16 1 3.14 16.25 0.11 6.45 19.96 0.08 0.04 19.16 0.07 0.32

 79 0.15 71.867 8223 2 135 0.05 0.090 16 1 1.96 14.37 0.10 8.34 18.55 0.07 1.46 17.97 0.07 1.51

 80 0.44 258.57 8054 13 45 0.15 0.110 16 3 2.58 14.97 0.09 7.75 18.57 0.07 1.44 17.72 0.06 1.77

 81 0.51 257.83 9570 26 90 0.35 0.350 16 4 2.09 14.30 0.06 8.45 18.85 0.06 1.17 17.43 0.05 2.07

 82 0.70 146.69 8487 12 180 0.25 0.240 16 1 3.53 16.90 0.10 5.81 20.17 0.07 -0.16 19.51 0.06 -0.02

 83 0.79 60.754 8875 5 90 0.15 0.170 16 2 2.28 14.71 0.08 8.02 19.17 0.06 0.85 17.61 0.05 1.89

 84 0.66 149.29 8480 13 45 0.15 0.170 16 3 6.35 17.27 0.17 5.37 20.34 0.10 -0.36 19.34 0.09 0.12

 85 0.75 138.54 8450 13 45 0.15 0.170 16 2 1.47 13.53 0.07 9.21 16.85 0.06 3.17 16.65 0.05 2.85

 86 0.74 966.70 8168 23 0 0.15 0.260 1 1 5.78 16.21 0.16 4.76 18.95 0.12 -0.09 16.16 0.07 -0.84

 87 0.71 192.45 9320 24 0 0.35 0.280 16 2 2.84 14.40 0.06 8.35 15.74 0.06 4.28 15.05 0.05 4.45

 88 0.13 81.128 8179 7 225 0.15 0.150 16 1 0.97 12.48 0.10 10.23 16.14 0.07 3.87 16.27 0.06 3.22

 89 0.40 379.71 8870 20 45 0.35 0.300 16 2 3.12 15.07 0.08 7.66 17.89 0.07 2.12 16.83 0.06 2.66

 90 0.75 195.59 8773 15 225 0.35 0.260 16 2 4.61 17.51 0.11 5.19 20.30 0.07 -0.29 19.68 0.07 -0.20

 91 0.71 154.10 8288 13 45 0.15 0.150 16 2 0.99 12.51 0.07 10.23 15.53 0.06 4.49 16.09 0.05 3.41

 92 0.59 136.69 8376 23 0 0.15 0.220 16 2 6.60 17.14 0.18 5.49 20.22 0.12 -0.26 19.08 0.09 0.38

 93 0.71 236.53 9685 21 45 0.45 0.390 16 4 2.42 13.93 0.06 8.82 16.23 0.06 3.79 15.73 0.04 3.78

 94 0.69 265.61 7919 20 45 0.35 0.270 1 1 5.63 16.27 0.15 4.71 18.89 0.12 -0.03 16.17 0.07 -0.85

 95 0.58 145.58 8279 4 135 0.15 0.210 16 1 2.75 15.94 0.09 6.78 20.01 0.07 0.00 18.94 0.06 0.55

 96 0.50 196.52 8128 19 315 0.25 0.240 1 1 5.25 16.07 0.15 4.91 18.81 0.11 0.06 16.13 0.07 -0.81

 97 0.31 118.73 8284 9 270 0.15 0.160 16 2 4.83 16.98 0.14 5.69 20.34 0.09 -0.35 19.53 0.09 -0.07

 98 0.65 98.725 8185 13 45 0.15 0.150 16 3 3.95 16.31 0.11 6.39 19.38 0.08 0.62 18.14 0.07 1.34

 99 0.11 94.464 8204 5 90 0.15 0.110 16 3 2.28 14.75 0.10 7.96 19.11 0.07 0.90 18.23 0.07 1.25

100 0.79 79.647 8354 13 45 0.15 0.160 16 1 1.46 13.57 0.07 9.17 16.96 0.06 3.06 16.80 0.05 2.70

101 0.43 167.44 8298 14 270 0.25 0.190 16 1 0.95 12.62 0.07 10.12 16.12 0.06 3.90 16.33 0.05 3.17

102 0.58 267.09 8317 25 90 0.25 0.240 1 1 6.96 17.38 0.19 3.56 19.29 0.12 -0.43 15.95 0.08 -0.64

103 0.66 75.943 8291 22 0 0.25 0.190 16 2 2.84 15.01 0.09 7.71 17.41 0.07 2.60 16.64 0.06 2.85

104 0.30 372.49 8346 13 45 0.15 0.150 16 3 4.80 16.58 0.14 6.09 20.34 0.09 -0.35 18.86 0.08 0.61

105 0.49 115.95 9231 4 135 0.15 0.190 16 3 2.10 14.65 0.08 8.08 19.44 0.06 0.58 18.26 0.06 1.23

106 0.67 215.60 8516 13 45 0.15 0.200 16 2 3.52 15.91 0.10 6.80 19.14 0.07 0.87 17.78 0.06 1.71

107 0.55 462.69 9244 17 45 0.25 0.260 16 3 2.00 13.58 0.06 9.17 16.81 0.06 3.21 16.13 0.04 3.38

108 0.44 317.66 8510 13 45 0.15 0.250 16 2 4.03 16.44 0.11 6.26 19.88 0.08 0.12 18.58 0.07 0.90

109 0.27 65.570 8361 4 135 0.15 0.160 16 3 3.12 16.27 0.11 6.43 20.44 0.08 -0.44 19.24 0.07 0.24

110 0.71 206.52 8686 22 0 0.25 0.230 16 2 1.92 13.58 0.06 9.17 16.16 0.06 3.86 15.55 0.05 3.95

111 0.69 189.30 8969 25 90 0.25 0.280 16 1 2.02 14.60 0.08 8.13 19.05 0.06 0.97 17.91 0.06 1.58

112 0.64 183.18 9161 24 0 0.35 0.28 16 1 2.15 13.47 0.06 9.28 15.41 0.06 4.61 14.97 0.04 4.54

 ----- ----- ----- ----- ----- ----- ----- ----- -----

area-weighted mean 15.68 0.14 5.97 17.58 0.08 0.39 17.25 0.07 0.23 

mean 15.49 0.13 6.34 17.69 0.07 0.61 17.35 0.06 0.52

median 15.92 0.12 5.89 17.53 0.07 -0.01 17.12 0.06 -0.17

minimum 10.76 0.06 2.76 11.47 0.03 -0.84 13.17 0.04 -1.01

maximum 17.99 0.24 10.54 20.44 0.12 5.68 19.84 0.09 5.73

 Base-flow reservoir summary

---------------------------------

ss-gw rcb gsnk area 

----- -------- ------- -----

 1 0.110000 0.04400 19524

 2 0.500000 0.11000 7927

 3 0.000500 0.00088 2307

 4 0.000550 0.00220 554

---------------------------------

--------------------------------------------------------------------------------------------------------------------------------------------
88 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

Interflow and Base-Flow Reservoir Delineation 

and Parameterization

The four rock groups—metamorphic, intrusive, 

fault zone, and Pikes Peak Granite—were fundamental to the process of defining the conceptual 

subsurface (interflow and base-flow) reservoirs used 

for accounting purposes by PRMS. These mappable 

rock groups were defined on the basis of differences in 

fracture or weathering characteristics with the underlying hypothesis that the level of fracturing or weathering is related to base-flow rates and to measurable 

differences in amount of ground water associated 

with streamflow. The short-term records of intrawatershed streamflow, described in the “Surface-Water 

Conditions” section, were established to measure 

such differences. The contributing drainage areas for 

the records of intrawatershed streamflow, which can 

be characterized in terms of hundreds of acres, define 

the resolution of knowledge concerning base-flow 

conditions established in this study.

Ideally, multiple streamflow records consisting 

of multiple years of record would be available for each 

rock group. Several factors, however, including but not 

limited to duration of the study, geographic constraints 

imposed by the mapped configuration of some rock 

groups, and logistical challenges associated with 

acquiring access to sites, influenced the availability 

of records. As a result, the short-term records were 

obtained in intrusive rocks (STR–3 and 4), faulted rocks 

(STR–2), and Pikes Peak Granite (STR–1) (table 2, 

table 6, fig. 23) but not metamorphic rocks. In addition, 

the intrawatershed records cover only about 4 months of 

streamflow; however, repetitive synoptic measurements 

of streamflow made throughout the watershed help 

offset these deficiencies. The synoptic measurements 

include results for all four rock groups. 

Results from the short-term records of streamflow 

indicate two general and distinct conditions of base flow 

in the watershed. The first and most prevalent condition 

is base flow in streams that is poorly sustained. This first 

condition was observed in intrusive rocks at STR–4 and 

at many of the synoptic measurements in intrusive and 

metamorphic rocks. The synoptic measurements indicate that, in general, much of the watershed has poorly 

sustained streamflow. The second condition is base flow 

that supports streamflow at relatively steady rates. This 

condition was found in the Pikes Peak Granite (STR–1) 

and fault-zone rocks (STR–2). Well-sustained streamflow emanating from the fault-zone rocks fits well with 

the findings presented in the “Estimates of Potential 

Fracture-Network Porosity” section. In addition, 

well-sustained streamflow emanating from Pikes Peak 

Granite fits well with the intuitive concept that the 

highly weathered Pikes Peak Granite may be capable 

of storing and slowly transmitting ground water to 

streams. However, well-sustained streamflow also 

was observed at STR–3, which drains intrusive rocks. 

Although the presence of well-sustained streamflow in 

some portions of the intrusive rocks does not support the 

hypothesis that the rock groups may uniquely influence 

ground-water conditions, the observed effect cannot be 

refuted on the basis of available records. One possible 

explanation for the well-sustained streamflow observed 

at STR–3 is that the geologic mapping, which is based 

mostly on rock composition, does not delineate fracture 

characteristics that transcend rock types.

On the basis of the rock group, and the streamflow records and synoptic measurements of streamflow described above, four conceptual interflow and 

base-flow reservoirs (fig. 42) were defined and used 

for accounting purposes in PRMS. Although the reservoirs are mappable and distinct from each other, they 

should not be considered distinct aquifers. Rather, 

each reservoir represents a part of a single aquifer 

system that behaves somewhat differently than the rest 

of the aquifer system. The watershed characterization 

implemented with PRMS facilitates quantitative 

descriptions of differences between base-flow reservoirs. Available records do not describe ground-water 

discharge conditions at a scale less than the contributing drainage areas for streamflow records, and 

there is no basis for undertaking detailed subsurface 

accounting at the HRU scale. 

The subsurface reservoirs are referred to as 

“metamorphic,” “intrusive,” “fault zone,” and “Pikes 

Peak Granite.” The reservoirs generally conform to 

the mapped rock groups. The metamorphic-rock reservoir was characterized with the results of synoptic 

streamflow measurements and watershed records. The 

intrusive-rock reservoir was characterized with records 

from STR–4. The fault-zone reservoir was represented 

with records from STR–2. Because short-term records 

of streamflow from STR–3 indicate base-flow characteristics similar to fault-zone rocks (STR–2), they 

were grouped together to characterize the fault-zone 

reservoir. Two additional HRU’s, 32 and 37, also 

were added to the fault-zone reservoir on the basis 

of synoptic measurements of discharge (SNGN6, 

table 15). The Pike Peak Granite reservoir was characterized with records from STR–1. In addition, any
ASSESSMENT OF WATER RESOURCES 89

isolated occurrence of a rock group that was less 

than about 40 acres in area was considered to be 

homogeneous with respect to its surroundings. Interflow reservoirs were defined to be coincident with 

base-flow reservoirs and, therefore, occur as a paired 

member to each base-flow reservoir. Each interflow 

and base-flow reservoir pair is associated with 

multiple HRU’s (table 24), and input to the base-flow 

reservoir is a combination of accretions from the soil 

moisture and interflow storage (fig. 13).

Initial input-parameter values for each interflow 

and base-flow reservoir were assigned on the basis 

of streamflow records, either from stream gages or 

synoptic measurements. Values for base-flow reservoir 

parameters that control the amount of water routed 

to streamflow were assigned so that areas that have 

poorly sustained streamflow would deplete their 

storage at relatively fast rates compared to areas 

that have well-sustained streamflow (table 24).

Distribution of Precipitation and Temperature Data

Precipitation and temperature data are the 

starting point for PRMS simulations, and the model is 

sensitive to these data. Each HRU is associated with a 

measured record of precipitation and temperature from 

designated sources. The location, period of record, and 

type of instrumentation for precipitation records were 

considered as the records to be associated with HRU’s 

were selected.

Study area

boundary

Parmalee Gulch

S. Turkey Creek

N. Turkey Cr

Giant Gulch

Turkey Creek Iowa Gulch

Lone Pine

Estates

Wild Rose Grange

Marshdale

Tiny

Town

Indian

Hills

Fenders

Phillipsburg

Homewood Park

Oehlmann

Park

Conifer

8

To Morrison

C470

Shadow Mountain Road

N. Turkey Creek Rd

Parma lee Gulch

Road

285

285

Marshdale





D

A

B

E

D C

F

L M

H

P

G

I

J

K

N

O

39°32'24"

39°30'36"

39°34'12"

39°36'

39°37'48"

105°23'24" 105 105°21'36" °19'48" 105°18' 105°16'12" 105°14'24" 105°12'36" 105°10'48"

EXPLANATION

Subsurface reservoirs

Subbasin

Drainage

Roads

Subbasin code

Population centers

House

0

0 0.5 1 1.5 2 2.5 3 KILOMETERS

0.5 1 1.5 2 2.5 3 MILES

Metamorphic

Intrusive

Fault zone

Pikes Peak Granite

Base modified from U.S. Geological Survey

digital data for 1:24,000 maps

Figure 42. Interflow and base-flow reservoirs delineated for use with the Precipitation-Runoff Modeling System in the Turkey 

Creek watershed.
90 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

For PRMS calibration, only data collected in the 

Turkey Creek watershed were used. Because records 

from some rain gages did not cover the entire calibration period, and also because many rain gages had 

substantial periods of missing record, a subset of the 

14 available watershed precipitation records (table 2) 

was used for PRMS calibration. Records that were not 

used directly in the calibration procedure were used 

indirectly to update other records according to proximity and the results of correlations among the gages 

(table 25). In general, records for tipping-bucket gages 

were preferred for summer periods, and records from 

weighing-bucket gages were preferred for winter 

periods. The rain gages selected for use in calibration 

(table 24) were associated with a number of HRU’s 

using a combination of the Theissen polygon method 

(Chow, 1964) and judgment. Monthly means for 

measured precipitation show considerable variation 

and generally do not correlate strongly with elevation 

(table 25).

Air-temperature records were available from 

both evapotranspiration sites, from RG12, and from 

four air-temperature monitors established in the spring 

of 2001 (table 2). None of these records covered the 

entire calibration period, and records from RG12 

and the evapotranspiration tower, which are located 

close to each other, were composited to obtain a 

single record for use with the model. The simulated 

results provide temperature at the HRU scale on the 

basis of the input record, elevation, slope, and aspect. 

Records from the air-temperature monitors established 

in spring 2001 were used to calibrate simulated 

temperature.

Model Calibration

Runoff models are typically calibrated to match 

observed (measured) data. In this study the principal 

calibration data consist of streamflow measured at 

stations 06710992 and 06710995 (SWA01, fig. 4). 

Streamflow measured at these sites represents the 

cumulative effect of all processes that generate streamflow in the watershed; that is to say, streamflow at 

these two stream gages is an integrated measurement 

of all watershed processes. For PRMS calibration, 

records of diversions to the Independent Highline 

ditch were added to streamflow records for 06710995. 

Intrawatershed measurements of streamflow and 

point measurements of other processes that are related 

to hydrologic conditions have the potential to provide

Table 25. Monthly means and selected summary statistics for measured precipitation

[Note: Identifier refers to local identifier or summary statistic; na, not applicable; Corr, 

 correlation coefficient between elevation and month mean; Rng/mn, range divided by mean; 

 Elevation, elevation in feet above NVGD29] 

------------------------------------------------------------------------------------------------------

Iden- Ele- Jan- Feb- Sep- Oc- No- Detifier vation uary ruary March April May June July August tember tober vember cember

------------------------------------------------------------------------------------------------------

RG1 7,460 0.29 0.46 1.10 5.41 3.30 2.62 3.42 4.30 0.82 0.95 0.41 0.42 

RG3 7,900 0.34 0.48 1.15 4.67 3.46 1.81 2.81 4.45 0.83 1.17 0.49 0.35

RG4 7,820 0.27 0.46 1.11 4.92 4.40 2.40 3.00 3.75 0.95 0.97 2.76 0.25

RG5 8,480 0.14 0.13 0.30 3.23 2.66 2.24 3.04 3.57 0.85 1.29 0.36 0.28

RG6 7,560 0.26 0.12 0.29 3.92 3.12 2.14 2.37 3.42 1.13 0.88 0.43 0.17

RG7 7,480 0.32 0.37 1.00 4.57 2.72 1.94 2.43 2.93 1.07 1.07 0.35 0.51

RG8 6,040 0.56 0.38 1.40 4.82 1.63 1.77 1.54 3.53 1.01 1.16 1.86 1.48

RG9 7,160 0.70 0.23 1.39 4.49 2.06 1.09 1.79 3.39 1.28 0.90 1.54 0.59

RG10 8,240 na 0.34 0.38 8.62 2.10 5.13 0.89 na na na na na 

RG11 8,180 0.85 0.32 1.20 5.65 2.10 1.94 1.95 2.40 0.89 0.88 1.44 1.38

RG12 8,200 0.31 0.54 1.00 1.30 2.46 2.54 3.37 3.30 1.81 1.09 0.68 0.32

RG13 7,730 0.39 0.60 1.34 1.96 2.31 1.87 2.83 2.67 1.40 1.28 0.69 0.59

RG14 6,890 0.44 0.65 1.32 1.80 2.19 1.82 2.88 2.61 1.20 1.16 0.74 0.60

RG15 8,440 0.62 0.77 1.38 2.77 2.55 2.86 3.05 1.49 0.71 0.52 0.60 0.28

RG16 8,200 0.83 0.33 1.20 4.83 2.77 1.41 2.86 3.29 0.92 1.15 0.70 1.87

 Selected summary statistics

Mean na 0.45 0.41 1.04 4.20 2.66 2.24 2.55 3.22 1.06 1.03 0.93 0.65

Median na 0.37 0.38 1.15 4.57 2.55 1.94 2.83 3.35 0.98 1.08 0.69 0.46

Minimum na 0.14 0.12 0.29 1.30 1.63 1.09 0.89 1.49 0.71 0.52 0.35 0.17 

Maximum na 0.85 0.77 1.40 8.62 4.40 5.13 3.42 4.45 1.81 1.29 2.76 1.87

Range na 0.71 0.65 1.11 7.32 2.77 4.04 2.53 2.96 1.10 0.77 2.41 1.70

Corr na -0.03 0.03 -0.34 -0.15 0.35 0.40 0.57 -0.21 -0.14 -0.20 -0.32 -0.22

Rng/mn na 1.58 1.58 1.06 1.74 1.04 1.80 0.99 0.92 1.04 0.75 2.59 2.61

------------------------------------------------------------------------------------------------------
ASSESSMENT OF WATER RESOURCES 91

significant refinements to modeling that addresses 

spatial differences in hydrologic responses within 

the watershed. Multiple intrawatershed records also 

provide a mechanism to cross-reference simulated 

results within the watershed and develop a calibration 

that integrates estimates for all measured streamflow 

data. Intrawatershed records of streamflow were available from four sites (STR–1, 2, 3, and 4), and point 

measurements of evapotranspiration and soil moisture 

were available at two sites (RG16, in HRU 80; and 

RG17, in HRU 47) as described in the “Evapotranspiration” section. The intrawatershed records of streamflow were used to verify that simulated rates of base 

flow matched measured base flow. The point measurements of evapotranspiration were used to verify that 

simulated evapotranspiration volumes are similar to 

observed volumes. 

PRMS provides a capability to evaluate 

parameter sensitivity that can be used as a guide 

to optimizing calibrations based on a user-specified 

objective function of differences between simulated 

and measured data (Troutman, 1985). The calibration 

developed in this study, however, was achieved 

by manually adjusting a relatively small number 

of input parameters to obtain a reasonable visual 

match between monthly and annual sums, as well as 

daily hydrographs of simulated and measured streamflow (Bevan, 1997). The principal parameters adjusted 

to achieve calibration are associated with soil-moisture 

accounting and routing water to and from interflow 

and base-flow reservoirs.

Watershed Calibration Procedures

The model was initially calibrated to measured 

streamflow for the watershed, and a satisfactory match 

between simulated and measured volumes was 

obtained. Because a goal of the study was to make 

estimates for ground-water conditions, which represent a subset of the entire watershed conditions, some 

preference was given to matching volumes, such as the 

amount of streamflow or evapotranspiration, during 

periods of months or years, over precisely matching 

hydrograph shape on a daily basis. A good volume 

match is very important to the assessment of water 

resources in the Turkey Creek watershed for several 

reasons, including the relatively small magnitude of 

watershed streamflow and the relatively large magnitude of evapotranspiration. The initial calibration was 

completed with minor adjustments made to optimize 

the match between hydrographs of simulated and 

measured streamflow; however, the volume match 

was preserved as closely as possible. 

Simulated evapotranspiration from the initial 

calibration was compared to measured evapotranspiration; the estimates were found to be biased low by 

about 20 percent. Low bias in simulated evapotranspiration led to high bias in simulated ground-water 

recharge. The simulated evapotranspiration, even 

though low biased, accounted for a large percentage of 

precipitation and appeared to be reasonable; the availability of evapotranspiration measurements guided 

calibration procedures to reduce the high bias present 

in simulated ground-water recharge.

Several methods, many involving energy terms, 

to improve the match between simulated and measured 

evapotranspiration were investigated. Soil moisture, 

however, was the single most important constraint to 

reducing the amount of bias in simulated evapotranspiration. To approach satisfactory matches between 

simulated and measured evapotranspiration, it was 

necessary to make upward adjustments to model 

parameters that control the amount of soil moisture 

available for evapotranspiration; these adjustments 

were made uniformly to all HRU’s. 

The results of adjustments made to reduce the 

low bias in simulated evapotranspiration were evaluated by comparing simulated results to measurements 

of evapotranspiration from the HRU’s where evapotranspiration was measured (HRU 47 and HRU 80). 

The evapotranspiration measurements, although they 

do integrate effects over an area of perhaps a few 

acres, are essentially point measurements compared 

to HRU estimates, which (for the HRU’s involved) 

have areas of hundreds of acres (table 24). Consequently, simulated results for HRU’s 47 and 80 likely 

represent a different set of physical conditions than 

local conditions in the vicinity of evapotranspiration 

measurements.

The same point-versus-area considerations 

apply to measurements of soil moisture associated 

with the evapotranspiration measurement. These 

considerations appear to be particularly pertinent to 

comparisons of simulated and measured soil moisture 

in HRU 47 (“meadow site”) described in the “Evapotranspiration” section. Simulated results for soil 

moisture were comparable to the measurements 

at the meadow site only when upward adjustments 

to model parameters controlling the amount of water 
92 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

available for evapotranspiration were so large that 

simulated streamflow in HRU 47 during periods of 

direct runoff was almost completely depleted. Streamflow records from STR–4, which includes HRU 47, 

however, indicate that direct runoff is common in 

HRU 47. This indication implies that soil moisture at 

the meadow site is not representative of the entirety 

of HRU 47 and supports the finding presented in 

the “Evapotranspiration” section that the supply of 

moisture available for evapotranspiration in the area 

of the evapotranspiration measurement was likely 

augmented by the locally shallow ground-water table. 

The results help to explain low-biased simulated 

evapotranspiration.

Intrawatershed Calibration Procedures

Intrawatershed calibrations were made on the 

basis of streamflow records available from STR–1, 2, 

3, and 4 and synoptic measurements of streamflow. 

Model parameters adjusted to achieve the calibration 

principally concerned interflow and base-flow 

accounting, although the maximum amount of water 

that can be transferred from soil moisture to ground 

water was decreased for fault-zone areas. As indicated 

in the “Surface-Water Conditions” section, short-term 

records of streamflow and synoptic streamflow 

measurements indicate well-sustained streamflow 

in some parts of the watershed and poorly sustained 

streamflow in other parts of the watershed. Water that 

has percolated to the conceptual base-flow reservoirs 

in PRMS is affected by the value of a base flow 

routing coefficient and the ground-water seepage coefficient; in both cases, higher values tend to deplete the 

reservoir rapidly, and lower values tend to allow water 

to accumulate in the reservoir. Relatively low values 

for the routing coefficient were selected in order to 

match measured streamflow emanating from the Pikes 

Peak Granite and fault-zone reservoirs (table 24). 

Conversely, relatively high values were selected to 

route water more rapidly from the metamorphic and 

intrusive reservoirs. Values for the seepage coefficient 

were set to prevent the amount of water in the baseflow reservoirs from producing simulated base-flow 

rates higher than measured base-flow rates.

Initial contents values for the base-flow reservoir also are an important part of the calibration. If 

these values are set too high, simulated base flow will 

be greater than measured base flow, or extremely low 

streamflows, such as those observed in the intrusiverock areas, will not be matched, or both. The contents 

of the base-flow reservoirs do not represent the total 

amount of ground water in the system; rather, the 

contents represent the amount of ground water available to support local streamflow. 

Final Calibration

The results of watershed and intrawatershed 

calibration procedures are shown in graphs and 

tables that compare simulated results to measured 

data. Hydrographs of simulated and measured streamflow (fig. 43) indicate that simulated results are an 

accurate representation of measured data. Simulated 

streamflow is higher than measured streamflow in the 

spring of 1999, a relatively wet period, and lower than 

measured streamflow in the spring of 2001, a relatively dry period; otherwise simulated streamflow 

closely matches measured streamflow; the mean of 

daily differences –0.0001 inch (table 26). Hydrographs 

of intrawatershed simulated streamflow provide a 

reasonable characterization of diverse intrawatershed 

processes (fig. 44). Intrawatershed simulated evapotranspiration compares favorably to measurements at 

the forest site (table 26) but is lower than measured 

evapotranspiration at the meadow site due to local 

conditions discussed in the “Watershed Calibration 

Procedures” section.

The measured data used to develop the final 

calibration include some of the extremes that can be 

expected in climatic data for precipitation and air 

temperature. However, the calibration period is relatively short, beginning in 1999 and ending in fall 2001, 

and a longer period of record would provide a much 

better description of climatic variability in the 

watershed.

Contemporary Simulations

Simulated results for some water-balance terms, 

by HRU, are shown in table 24. Additional waterbalance summaries in table 27, table 28, and table 29 

are more complete and include daily, monthly, and 

annual simulated hydrologic watershed and intrawatershed conditions, based on data collected as part 

of this study. Simulated results qualified with the term 

“watershed” indicate area-weighted results, either by 

HRU or subsurface reservoir, for the entire watershed.
ASSESSMENT OF WATER RESOURCES 93

Note: Measured streamflow missing

 April 15 to June 1, 2000

Total flow

Surface runoff

Interflow

Base flow

Contents of interflow reservoir

Contents of base-flow reservoir

Measured streamflow

Simulated streamflow

0.20

0.15

0.10

0.05

0

SIMULATED STREAMFLOW, IN INCHES

250

200

150

100

50

1999 2000 2001 2002

0

STREAMFLOW, IN CUBIC FEET PER SECOND

1.0

0.8

0.6

0.4

0.2

0

SIMLUATED CONTENTS, IN INCHES

A

B

Figure 43. Watershed hydrographs of contemporary simulated and measured results.
94 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

Metamorphic rocks

Intrusive rocks

Faulted rocks

Pikes Peak Granite

Note: Colors indicate rock groups in subplot D

101

100

10–1

10–2

10–3

10–4

8

6

4

2

1999 2000 2001 2002

0

SIMULATED CONTENTS OF BASE-FLOW RESERVOIR, IN INCHES SIMULATED CONTENTS OF BASE-FLOW RESERVOIR, IN INCHES

C

D

Figure 43. Watershed hydrographs of contemporary simulated and measured results—Continued.
ASSESSMENT OF WATER RESOURCES 95

Table 24 lists annual residuals between precipitation, evapotranspiration, and overland flow on an HRU 

basis. This residual was referred to as “infiltration (I)” 

in evapotranspiration discussions but is generally 

referred to here as “ground-water recharge.” Annual 

recharge is sometimes identified as a theoretical upper 

bound to water that might be safely available for withdrawal by wells, in part because it is often thought that 

recharge is a good surrogate for the amount of water 

that will be replaced on an annual basis. Ground-water 

recharge is only a portion of the total amount of ground 

water in the system. Ground-water recharge supplies 

interflow, base flow, and GSNK. Consequently, much 

ground-water recharge leaves the watershed as streamflow. If there were some mechanism to withdraw 

the annual recharge as it occurred, then streamflow 

in the Turkey Creek watershed would consist only of 

overland flow. Interflow quickly leaves the watershed, 

whereas base flow typically persists for longer periods 

of time.

Simulated results for ground-water recharge, as 

used in this report and shown as “rsd” in table 24, varies 

considerably from HRU to HRU. HRU differences in 

ground-water recharge result from the physical 

characteristics of the watershed, the atmospheric energy 

conditions, and the availability of water, all of which 

are accounted for in the PRMS characterization of 

the watershed. During a wet period, such as the 

January through September portion of 1999, simulated 

results indicate that ground-water recharge is always

Table 26. Watershed and intrawatershed calibration statistics

[All values except Nmiss are inches; Min, minimum; Max, maximum; Period, January 1,

 1999 - September 30, 2001; WY, water year; Nmiss, number of missing days; ET, 

 evapotranspiration; --, not applicable; <, less than]

---------------------------------------------------------------------------------

 Watershed streamflow

 Mean Median Min Max Sum

---------------------------------------------------------------------------------

Simulated streamflow 0.0053 0.0005 0.0001 0.1568 5.09

Measured streamflow .0052 .0012 -- .1393 4.96

Difference -.0001 .0003 -.0553 .0407 .1315

 Intrawatershed streamflow

 Intrusive rocks 

 

Simulated streamflow 0.008 0.0013 <0.0001 0.092 0.879

Measured streamflow 0.007 0.0045 <0.0001 0.054 0.822

Difference -0.001 0.0002 -0.0489 0.017 -0.059

 Fault-zone rocks 

 

Simulated streamflow 0.008 0.002 0.0007 0.061 0.924

Measured streamflow 0.015 0.010 0.0019 0.076 1.712

Difference 0.007 0.005 -0.0088 0.021 0.788

 

 Pikes Peak Granite

Simulated streamflow 0.007 0.003 0.002 0.033 0.785

Measured streamflow 0.006 0.004 0.001 0.042 0.707

Difference -0.001 -0.001 -0.026 0.016 -0.077

 

 Intrawatershed ET

 Calibration Period WY1999 

 Mean Sum Nmiss Mean Sum Nmiss

 

Measured forest ET 0.051 51.50 34 0.051 18.73 0

Simulated forest ET 0.051 51.12 0 0.047 17.15 0

Measured meadow ET 0.066 32.03 542 -- -- 365

Simulated meadow ET 0.053 53.80 0 0.051 18.60 0

 

 

 WY2000 WY2001 

Measured forest ET 0.047 17.34 0 0.057 15.43 0

Simulated forest ET 0.049 17.81 0 0.059 16.17 0

Measured meadow ET 0.060 12.82 154 0.070 19.20 0

Simulated meadow ET 0.047 17.46 0 0.065 17.73 0

---------------------------------------------------------------------------------
96 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

positive and, on a watershed scale, has a magnitude 

of 5.97 inches. For the same period, on an HRU scale, 

simulated results indicate ground-water recharge ranges 

from 2.76 inches to as much as 10.54 inches. However, 

during a relatively dry period, such as water year 2001, 

the results are strikingly different. In fact, during water 

year 2001, simulated results for the watershed indicate 

0.39 inch, or about 6.5 percent of the 1999 value, of 

ground-water recharge; and at many HRU’s the estimates are negative, indicating a condition in which 

evapotranspiration is depleting water in storage (as 

discussed in the “Evapotranspiration” section eq. 4). 

For these and other reasons, such as the fact that much 

ground-water recharge leaves the watershed as streamflow, annual estimates of ground-water recharge are 

not the optimal predictor of ground-water availability, 

and it is desirable to have estimates that describe the 

status of water in the interflow and, particularly, baseflow reservoirs as characterized by PRMS. 

Table 27 provides monthly and annual summary 

information for hydrologic conditions such as the 

amount of precipitation, evapotranspiration, soil moisture, the contents of interflow and base-flow reservoirs, GSNK, overland flow, interflow, and base flow. 

Most results listed in table 27 are totals for the period 

of evaluation; for instance, precipitation figures indicate a total amount of precipitation for the given 

month or year. Contents results (sm, bfr, ir in table 27), 

however, indicate the contents on the last day of 

the given month or year. The simulated results listed 

A. Pikes Peak Granite

B. Fault-zone rocks

C. Intrusive rocks

Simulated

Measured

Simulated

Measured

Simulated

Measured

103

102

101

100

10–1

10–2

10–3

10–4

10–5

10–6

10–7

103

102

101

100

10–1

10–2

10–3

10–4

10–5

10–6

10–7

103

102

101

100

10–1

10–2

10–3

10–4

10–5

10–6

10–7

STREAMFLOW, IN INCHES STREAMFLOW, IN INCHES STREAMFLOW, IN INCHES

APRIL MAY JUNE JULY AUGUST

 Figure 44. Intrawatershed hydrographs of contemporary simulated and measured results.
ASSESSMENT OF WATER RESOURCES 97

in table 27 indicate that watershed values for the 

contents of the base-flow reservoirs are generally 0.1 

to 0.2 inch at the end of each water year; this water is 

potentially available to supply wells. The watershed 

representation for the contents of the base-flow reservoirs (fig. 43) indicates that at least this amount of 

water is consistently present, on a watershed scale.

The end-of-year watershed contents of interflow 

reservoirs is typically very near 0.0000 (table 27). The 

watershed representation for contents of the interflow 

reservoir (fig. 43A) indicates that, unlike the watershed 

representation of the base-flow reservoirs, the interflow 

reservoirs fill and deplete rapidly and are most likely to 

contain water during and shortly after precipitation or 

spring runoff. Water contained in the interflow reservoirs is, like water contained in the base-flow reservoirs, 

potentially available to supply wells. However, water in 

the interflow reservoirs is typically present only for 

short periods of time related to precipitation or snowmelt events.

Table 27. Monthly and annual summary statistics for contemporary simulations (January 1, 1999, 

through September 30, 2001) for the entire Turkey Creek watershed

[Year, water year (October through September) if month not given; Mo, month; all numbers other 

 than dates in inches; Precip,total precipitation; ET, total evapotranspiration; sm, contents of 

 soil-zone reservoir at end of given period; bfi, total water added to base-flow reservoir;

 bfr, contents of base flow reservoir at end of accounting period; bf, total base flow 

 discharged to stream; gsnk, total water lost from base-flow reservoir that is not available to 

 support local streamflow; ir, contents of interflow reservoir at end of the accounting period; if, 

 total interflow; ovf, total overland flow; tf, total watershed flow] 

------------------------------------------------------------------------------------------------------

Year Mo Precip ET sm bfi bfr bf gsnk ir if ovf tf 

------------------------------------------------------------------------------------------------------

1999 1 0.5739 0.2149 0.4103 0.0000 0.1148 0.0027 0.0052 0.0000 0.0000 0.0008 0.0036

1999 2 0.2828 0.3735 0.3668 0.0000 0.1088 0.0017 0.0043 0.0000 0.0000 0.0007 0.0024

1999 3 0.4561 0.5550 0.2670 0.0000 0.1026 0.0018 0.0044 0.0000 0.0000 0.0008 0.0026

 

1999 4 6.9443 0.8300 3.9826 0.5410 0.3750 0.2116 0.0570 0.6542 0.1398 0.0157 0.3670

1999 5 4.0518 3.1074 3.5065 1.0510 0.3421 0.8591 0.2247 0.5581 1.4703 0.0428 2.3722

1999 6 1.7843 3.6532 1.6121 0.0140 0.2440 0.0768 0.0354 0.0685 0.4865 0.0153 0.5786

 

1999 7 2.6156 1.7375 2.4511 0.0116 0.2355 0.0086 0.0116 0.0221 0.0557 0.0170 0.0813

1999 8 4.0234 3.7386 2.2448 0.1713 0.2401 0.1238 0.0428 0.0459 0.2604 0.0368 0.4211

1999 9 1.0532 1.4890 1.8016 0.0001 0.2249 0.0049 0.0105 0.0093 0.0364 0.0059 0.0472

 ----------------------------------------------------------------------------------------

1999 21.7855 15.6991 1.8016 1.7890 0.2249 1.2910 0.3958 0.0093 2.4491 0.1359 3.8761

 

1999 10 1.0461 1.2213 1.6792 0.0000 0.2115 0.0037 0.0097 0.0019 0.0074 0.0024 0.0135

1999 11 0.6593 0.5881 1.7288 0.0039 0.2008 0.0052 0.0093 0.0019 0.0019 0.0013 0.0084

1999 12 1.0468 0.5194 2.0843 0.0404 0.1946 0.0314 0.0152 0.0063 0.0055 0.0014 0.0383

 

2000 1 0.4969 0.4532 1.8454 0.0105 0.1770 0.0166 0.0114 0.0009 0.0055 0.0002 0.0223

2000 2 0.6033 0.8462 1.9174 0.0416 0.1744 0.0308 0.0133 0.0062 0.0080 0.0028 0.0417

2000 3 2.4735 1.0712 2.4385 0.0792 0.1844 0.0518 0.0174 0.0096 0.0157 0.0018 0.0693

 

2000 4 2.2362 2.3592 2.6116 0.1622 0.2058 0.1098 0.0310 0.0169 0.1021 0.0094 0.2213

2000 5 1.4886 2.9785 1.3496 0.0036 0.1921 0.0076 0.0097 0.0026 0.0142 0.0089 0.0307

2000 6 1.5576 1.3943 1.5006 0.0017 0.1812 0.0046 0.0080 0.0011 0.0027 0.0093 0.0166

 

2000 7 1.5432 2.0604 0.9474 0.0119 0.1733 0.0103 0.0094 0.0047 0.0109 0.0096 0.0308

2000 8 3.4605 2.1231 2.2449 0.0145 0.1657 0.0127 0.0094 0.0019 0.0051 0.0232 0.0410

2000 9 1.4314 1.9466 1.7202 0.0023 0.1547 0.0062 0.0073 0.0006 0.0017 0.0066 0.0145

 ---------------------------------------------------------------------------------------- 

2000 18.0434 17.5615 1.7202 0.3716 0.1547 0.2906 0.1513 0.0006 0.1807 0.0770 0.5483

 

2000 10 0.5499 0.9592 1.2887 0.0000 0.1457 0.0027 0.0063 0.0001 0.0005 0.0022 0.0054

2000 11 0.5995 0.3868 1.4883 0.0067 0.1392 0.0062 0.0070 0.0005 0.0003 0.0011 0.0076

2000 12 0.4280 0.3592 1.4950 0.0101 0.1315 0.0100 0.0078 0.0001 0.0004 0.0007 0.0111

 

2001 1 0.3750 0.3258 1.4223 0.0013 0.1229 0.0041 0.0058 0.0000 0.0001 0.0002 0.0044

2001 2 0.7607 0.6732 1.5481 0.0234 0.1172 0.0204 0.0088 0.0005 0.0024 0.0015 0.0243

2001 3 1.5679 0.9600 2.0801 0.0943 0.1303 0.0632 0.0179 0.0100 0.0152 0.0058 0.0842

 

2001 4 2.5812 2.2242 2.2095 0.2156 0.1808 0.1327 0.0324 0.0280 0.0708 0.0036 0.2071

2001 5 3.0564 3.0570 1.8520 0.2138 0.1832 0.1650 0.0464 0.0209 0.1444 0.0064 0.3158

2001 6 0.8613 1.7524 0.9564 0.0001 0.1709 0.0045 0.0080 0.0040 0.0168 0.0047 0.0260

 

2001 7 2.8911 2.1995 1.6288 0.0020 0.1612 0.0040 0.0075 0.0008 0.0032 0.0173 0.0246

2001 8 2.5259 2.7870 1.3417 0.0062 0.1515 0.0081 0.0078 0.0003 0.0021 0.0180 0.0282

2001 9 1.3463 1.5734 1.1093 0.0006 0.1429 0.0029 0.0063 0.0001 0.0002 0.0049 0.0081

 ---------------------------------------------------------------------------------------- 

2001 17.5432 17.2576 1.1093 0.5742 0.1429 0.4238 0.1621 0.0001 0.2564 0.0665 0.7467

 

Period 57.372 50.518 1.109 2.735 0.143 2.006 0.709 0.000 2.886 0.279 5.171

----------------------------------------------------------------------------------------------------- 
98 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

In addition to estimates for the contents of the 

base-flow reservoir at a watershed scale, the simulated results in table 27 indicate about 1.6 inches 

of recharge to the watershed base-flow reservoir 

occurred in April and May of 1999, and that much 

less water (about an order of magnitude less) was 

recharged to the base-flow reservoir in 2000 and 

2001. The watershed representation for contents of 

the base-flow reservoirs (fig. 43) generally indicates 

that contents can undergo relatively rapid changes. 

Contents typically exhibit a relatively abrupt 

increase during spring recharge and decrease more 

slowly. In general, the recession slope for the watershed representation of contents of the base-flow 

reservoir appears to be about a few hundredths of 

an inch per year. 

Table 28. Intrawatershed summary statistics for contemporary simulations (January 1, 1999, 

through September 30, 2001) for areas of (A) metamorphic,(B) intrusive, and (C) fault-zone 

rocks and (D) Pikes Peak Granite

[Year, water year (October through September) if month not given; Mo, month; all numbers other 

 than dates in inches; Precip,total precipitation; ET, total evapotranspiration; sm, contents of 

 soil-zone reservoir at end of given period; bfi, total water added to base-flow reservoir;

 bfr, contents of base flow reservoir at end of accounting period; bf, total base flow 

 discharged to stream; gsnk, total water lost from base-flow reservoir that is not available to 

 support local streamflow; ir, contents of interflow reservoir at end of the accounting period; if, 

 total interflow; ovf, total overland flow; tf, total watershed flow]

------------------------------------------------------------------------------------------------------

Year Mo Precip ET sm bfi bfr bf gsnk ir if ovf tf 

------------------------------------------------------------------------------------------------------

 A. Metamorphic rocks

1999 1 0.5239 0.2200 0.3695 0.0000 0.0000 0.0007 0.0003 0.0000 0.0000 0.0008 0.0015

1999 2 0.2708 0.3436 0.3325 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0008 0.0008

1999 3 0.4485 0.5336 0.2480 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0009 0.0009

 

1999 4 6.8452 0.8507 4.1863 0.6242 0.3690 0.1882 0.0670 0.8146 0.1330 0.0197 0.3409

1999 5 3.9007 3.1571 3.5320 0.8114 0.1338 0.7718 0.2748 0.6123 1.2724 0.0433 2.0875

1999 6 1.6838 3.5910 1.6118 0.0084 0.0018 0.1036 0.0369 0.1040 0.5095 0.0145 0.6276

 

1999 7 2.5087 1.7235 2.3730 0.0086 0.0068 0.0027 0.0010 0.0296 0.0838 0.0164 0.1029

1999 8 4.2358 3.8260 2.3164 0.1546 0.0021 0.1175 0.0418 0.0691 0.2557 0.0396 0.4129

1999 9 1.0845 1.5320 1.8640 0.0001 0.0000 0.0016 0.0006 0.0145 0.0545 0.0065 0.0626

 

1999 21.5020 15.7774 1.8640 1.6074 0.0000 1.1861 0.4223 0.0145 2.3090 0.1426 3.6377

 

1999 10 1.0165 1.2032 1.7103 0.0000 0.0000 0.0000 0.0000 0.0029 0.0115 0.0023 0.0138

1999 11 0.6699 0.5979 1.7655 0.0050 0.0022 0.0021 0.0007 0.0030 0.0029 0.0016 0.0065

1999 12 0.9684 0.5683 2.0707 0.0392 0.0102 0.0231 0.0082 0.0065 0.0045 0.0019 0.0294

 

2000 1 0.4248 0.4568 1.7810 0.0081 0.0007 0.0129 0.0046 0.0013 0.0052 0.0003 0.0184

2000 2 0.6341 0.8126 1.8498 0.0327 0.0054 0.0207 0.0074 0.0077 0.0074 0.0030 0.0310

2000 3 2.4042 1.0872 2.3389 0.0480 0.0114 0.0309 0.0110 0.0073 0.0096 0.0024 0.0429

 

2000 4 2.2525 2.3801 2.5965 0.0873 0.0040 0.0699 0.0249 0.0196 0.0497 0.0091 0.1287

2000 5 1.4058 2.8852 1.3587 0.0005 0.0000 0.0033 0.0012 0.0040 0.0156 0.0084 0.0273

2000 6 1.6279 1.4275 1.5535 0.0001 0.0001 0.0001 0.0000 0.0009 0.0031 0.0099 0.0131

 

2000 7 1.3888 1.9810 0.9365 0.0094 0.0008 0.0064 0.0023 0.0063 0.0075 0.0086 0.0225

2000 8 3.3290 2.0390 2.2067 0.0117 0.0030 0.0070 0.0025 0.0024 0.0061 0.0225 0.0356

2000 9 1.5352 1.9562 1.7814 0.0002 0.0001 0.0023 0.0008 0.0005 0.0019 0.0073 0.0115

 

2000 17.6572 17.3951 1.7814 0.2425 0.0001 0.1788 0.0636 0.0005 0.1249 0.0772 0.3808

 

2000 10 0.5912 1.0282 1.3208 0.0000 0.0000 0.0001 0.0000 0.0001 0.0004 0.0025 0.0030

2000 11 0.5821 0.4060 1.4924 0.0104 0.0024 0.0059 0.0021 0.0007 0.0005 0.0011 0.0075

2000 12 0.4264 0.3783 1.4914 0.0124 0.0025 0.0091 0.0032 0.0001 0.0006 0.0008 0.0105

 

2001 1 0.3690 0.3374 1.4142 0.0021 0.0004 0.0030 0.0011 0.0000 0.0001 0.0002 0.0033

2001 2 0.7138 0.6951 1.4763 0.0210 0.0012 0.0149 0.0053 0.0004 0.0005 0.0017 0.0172

2001 3 1.4917 0.9801 1.9445 0.0654 0.0107 0.0412 0.0147 0.0090 0.0084 0.0057 0.0553

 

2001 4 2.4784 2.2291 2.0871 0.1230 0.0274 0.0783 0.0279 0.0204 0.0263 0.0044 0.1091

2001 5 2.9895 3.0544 1.7850 0.1528 0.0032 0.1305 0.0465 0.0288 0.0794 0.0066 0.2165

2001 6 0.8507 1.6827 0.9513 0.0000 0.0000 0.0024 0.0009 0.0061 0.0227 0.0048 0.0299

 

2001 7 2.8193 2.0815 1.6851 0.0024 0.0007 0.0013 0.0005 0.0013 0.0049 0.0170 0.0232

2001 8 2.5148 2.9058 1.2797 0.0036 0.0001 0.0030 0.0011 0.0004 0.0013 0.0184 0.0228

2001 9 1.3485 1.5163 1.1095 0.0010 0.0000 0.0008 0.0003 0.0001 0.0003 0.0048 0.0060

 

2001 17.1752 17.2950 1.1095 0.3941 0.0000 0.2907 0.1035 0.0001 0.1454 0.0681 0.5042

 

Period 56.334 50.467 1.110 2.244 0.000 1.656 0.589 0.000 2.579 0.288 4.523
ASSESSMENT OF WATER RESOURCES 99

The combination of the distributed nature of 

PRMS and intrawatershed measurements of streamflow permits simulations for the individual subsurface 

reservoirs. The results from individual base-flow 

reservoirs (table 28 and fig. 43) indicate how intrawatershed conditions vary. Figure 43 provides a 

graphic summary of the contents of the four base-flow 

reservoirs and indicates that the Pikes Peak Granite 

and fault-zone reservoirs have a tendency to receive 

and retain ground water and slowly release it as base 

flow that sustains streamflow. The intrusive reservoir, 

and to a lesser extent the metamorphic reservoir, 

however, do not retain and slowly release ground 

water to sustain streamflow. The contents of the

Table 28. Intrawatershed summary statistics for contemporary simulations (January 1, 1999, 

through September 30, 2001) for areas of (A) metamorphic, (B) intrusive, and (C) fault-zone 

rocks and (D) Pikes Peak Granite—Continued

[Year, water year (October through September) if month not given; Mo, month; all numbers other 

 than dates in inches; Precip,total precipitation; ET, total evapotranspiration; sm, contents of 

 soil-zone reservoir at end of given period; bfi, total water added to base-flow reservoir;

 bfr, contents of base flow reservoir at end of accounting period; bf, total base flow 

 discharged to stream; gsnk, total water lost from base-flow reservoir that is not available to 

 support local streamflow; ir, contents of interflow reservoir at end of the accounting period; if, 

 total interflow; ovf, total overland flow; tf, total watershed flow]

-----------------------------------------------------------------------------------------------------

Year Mo Precip ET sm bfi bfr bf gsnk ir if ovf tf 

-----------------------------------------------------------------------------------------------------

 B. Intrusive rocks

1999 1 0.6078 0.1939 0.4480 0.0000 0.0000 0.0009 0.0001 0.0000 0.0000 0.0011 0.0020

1999 2 0.2877 0.4089 0.4005 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0006 0.0006

1999 3 0.4547 0.5679 0.2914 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0006 0.0006

 

1999 4 6.9142 0.7908 3.7721 0.4484 0.0719 0.3393 0.0373 0.3529 0.1371 0.0092 0.4855

1999 5 4.4471 3.0427 3.6522 1.4646 0.0136 1.3719 0.1509 0.4553 1.6153 0.0464 3.0337

1999 6 1.9327 3.8457 1.7292 0.0118 0.0000 0.0229 0.0025 0.0044 0.4532 0.0169 0.4930

 

1999 7 2.8099 1.8504 2.6509 0.0189 0.0070 0.0107 0.0012 0.0106 0.0052 0.0184 0.0344

1999 8 3.7093 3.6669 2.2467 0.1798 0.0000 0.1683 0.0185 0.0035 0.2548 0.0330 0.4561

1999 9 1.0055 1.4678 1.7808 0.0000 0.0000 0.0000 0.0000 0.0000 0.0035 0.0052 0.0087

 

1999 22.1688 15.8349 1.7808 2.1235 0.0000 1.9140 0.2105 0.0000 2.4691 0.1315 4.5146

 

1999 10 1.0823 1.2170 1.7024 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0027 0.0028

1999 11 0.6225 0.5631 1.7397 0.0023 0.0002 0.0019 0.0002 0.0000 0.0000 0.0011 0.0030

1999 12 1.0662 0.4174 2.1174 0.0575 0.0017 0.0504 0.0055 0.0082 0.0099 0.0007 0.0610

 

2000 1 0.5431 0.4225 1.9468 0.0203 0.0000 0.0198 0.0022 0.0001 0.0081 0.0002 0.0281

2000 2 0.5992 0.8725 2.0494 0.0627 0.0000 0.0565 0.0062 0.0018 0.0043 0.0030 0.0637

2000 3 2.5491 1.0514 2.6284 0.1244 0.0015 0.1107 0.0122 0.0030 0.0094 0.0008 0.1209

 

2000 4 2.2630 2.3382 2.7274 0.2596 0.0001 0.2351 0.0259 0.0083 0.1383 0.0098 0.3832

2000 5 1.6220 3.1557 1.4218 0.0087 0.0000 0.0079 0.0009 0.0001 0.0102 0.0102 0.0283

2000 6 1.4609 1.3827 1.4840 0.0062 0.0001 0.0055 0.0006 0.0022 0.0028 0.0083 0.0166

 

2000 7 1.6959 2.1505 0.9958 0.0133 0.0000 0.0121 0.0013 0.0018 0.0173 0.0104 0.0399

2000 8 3.6839 2.3020 2.3483 0.0231 0.0005 0.0204 0.0022 0.0011 0.0037 0.0245 0.0485

2000 9 1.2654 1.9340 1.6653 0.0083 0.0002 0.0078 0.0009 0.0009 0.0020 0.0058 0.0156

 

2000 18.4534 17.8072 1.6653 0.5863 0.0002 0.5280 0.0581 0.0009 0.2060 0.0775 0.8115

 

2000 10 0.4913 0.8481 1.2820 0.0000 0.0000 0.0002 0.0000 0.0000 0.0009 0.0018 0.0029

2000 11 0.5883 0.3462 1.5091 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0011 0.0011

2000 12 0.4144 0.3193 1.5269 0.0081 0.0001 0.0072 0.0008 0.0000 0.0000 0.0004 0.0076

 

2001 1 0.3607 0.3072 1.4550 0.0000 0.0000 0.0001 0.0000 0.0000 0.0000 0.0001 0.0002

2001 2 0.7901 0.6155 1.6764 0.0379 0.0000 0.0341 0.0038 0.0008 0.0079 0.0014 0.0434

2001 3 1.6663 0.9300 2.3024 0.1502 0.0031 0.1326 0.0146 0.0032 0.0159 0.0064 0.1549

 

2001 4 2.6967 2.2167 2.4386 0.3387 0.0023 0.3058 0.0336 0.0216 0.0833 0.0022 0.3914

2001 5 3.1515 3.0748 2.0327 0.3281 0.0000 0.2977 0.0327 0.0046 0.1823 0.0064 0.4863

2001 6 0.8607 1.8707 1.0258 0.0000 0.0000 0.0000 0.0000 0.0000 0.0045 0.0046 0.0091

 

2001 7 2.9964 2.3868 1.6383 0.0015 0.0000 0.0014 0.0002 0.0000 0.0000 0.0179 0.0194

2001 8 2.5168 2.6515 1.4764 0.0149 0.0000 0.0135 0.0015 0.0001 0.0049 0.0173 0.0357

2001 9 1.3247 1.6416 1.1615 0.0000 0.0000 0.0000 0.0000 0.0000 0.0001 0.0047 0.0049

 

2001 17.8578 17.2083 1.1615 0.8795 0.0000 0.7925 0.0872 0.0000 0.2999 0.0644 1.1569

 

Period 58.480 50.850 1.162 3.589 0.000 3.235 0.356 0.000 2.975 0.273 6.483
100 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

metamorphic and intrusive base-flow reservoirs 

are, much like interflow, quickly transmitted to 

streamflow. Contents of the metamorphic and intrusive 

base-flow reservoirs have large fluctuations, and these 

portions of the watershed contribute to the rapid 

changes in the watershed contents of base-flow 

reservoirs.

Daily values for water-balance terms for watershed and intrawatershed conditions are summarized in 

table 29. The percentiles in table 29A reiterate that the 

watershed content of base-flow reservoirs is consistently in the range of 0.1 to 0.2 inch and that the watershed content of interflow reservoirs is very low most of 

the time (0.0020 for 50 percent of the time, table 29A).

Table 28. Intrawatershed summary statistics for contemporary simulations (January 1, 1999, 

through September 30, 2001) for areas of A) metamorphic, (B) intrusive, and (C) fault-zone 

rocks and (D) Pikes Peak Granite—Continued

[Year, water year (October through September) if month not given; Mo, month; all numbers other 

 than dates in inches; Precip,total precipitation; ET, total evapotranspiration; sm, contents of 

 soil-zone reservoir at end of given period; bfi, total water added to base-flow reservoir;

 bfr, contents of base flow reservoir at end of accounting period; bf, total base flow 

 discharged to stream; gsnk, total water ;ost from base-flow reservoir that is not available to 

 support local streamflow; ir, contents of interflow reservoir at end of the accounting period; if, 

 total interflow; ovf, total overland flow; tf, total watershed flow]

-----------------------------------------------------------------------------------------------------

Year Mo Precip ET sm bfi bfr bf gsnk ir if ovf tf 

-----------------------------------------------------------------------------------------------------

 C. Fault-zone rocks

1999 1 0.8184 0.2540 0.6067 0.0000 0.9566 0.0167 0.0267 0.0000 0.0000 0.0006 0.0172

1999 2 0.3013 0.4887 0.4985 0.0000 0.9191 0.0145 0.0231 0.0000 0.0000 0.0008 0.0153

1999 3 0.4818 0.6642 0.3247 0.0000 0.8792 0.0153 0.0245 0.0000 0.0000 0.0004 0.0158

 

1999 4 7.6580 0.8183 3.7572 0.1775 1.0190 0.0145 0.0232 0.4685 0.2345 0.0092 0.2582

1999 5 3.7047 3.0481 3.3712 0.8764 1.8288 0.0256 0.0410 0.4313 2.7045 0.0337 2.7639

1999 6 1.8813 3.7291 1.5152 0.0250 1.7762 0.0298 0.0477 0.0035 0.4160 0.0157 0.4615

 

1999 7 2.7148 1.7022 2.5011 0.0140 1.7132 0.0297 0.0474 0.0031 0.0036 0.0173 0.0506

1999 8 3.6310 3.6739 1.9828 0.1320 1.7660 0.0304 0.0487 0.0048 0.3190 0.0312 0.3806

1999 9 1.0138 1.3538 1.6420 0.0001 1.6920 0.0285 0.0456 0.0000 0.0046 0.0050 0.0382

 

1999 22.2052 15.7323 1.6420 1.2250 1.6920 0.2051 0.3280 0.0000 3.6822 0.1139 4.0012

 

1999 10 1.0868 1.2343 1.5358 0.0000 1.6186 0.0282 0.0452 0.0000 0.0000 0.0016 0.0299

1999 11 0.7227 0.6067 1.6120 0.0000 1.5506 0.0262 0.0418 0.0000 0.0000 0.0005 0.0267

1999 12 1.3275 0.4622 2.1922 0.0006 1.4840 0.0259 0.0414 0.0000 0.0000 0.0003 0.0262

 

2000 1 0.8610 0.5265 2.1044 0.0000 1.4196 0.0248 0.0396 0.0000 0.0000 0.0002 0.0250

2000 2 0.3509 0.9854 2.0658 0.0540 1.4150 0.0225 0.0360 0.0108 0.0280 0.0010 0.0516

2000 3 2.6889 1.0085 2.6827 0.1495 1.5010 0.0244 0.0391 0.0536 0.0927 0.0005 0.1177

 

2000 4 1.9881 2.3258 2.5268 0.1478 1.5805 0.0263 0.0420 0.0060 0.3713 0.0104 0.4080

2000 5 1.7306 3.1786 1.2714 0.0002 1.5121 0.0264 0.0422 0.0000 0.0058 0.0093 0.0415

2000 6 1.2987 1.2709 1.2864 0.0000 1.4486 0.0244 0.0391 0.0000 0.0000 0.0072 0.0317

 

2000 7 2.1718 2.3935 1.0129 0.0180 1.4034 0.0243 0.0389 0.0025 0.0204 0.0146 0.0593

2000 8 3.5247 2.2935 2.2283 0.0119 1.3544 0.0234 0.0375 0.0000 0.0024 0.0232 0.0490

2000 9 1.3214 1.9262 1.6176 0.0000 1.2975 0.0219 0.0350 0.0000 0.0000 0.0052 0.0271

 

2000 19.0731 18.2121 1.6176 0.3821 1.2975 0.2988 0.4778 0.0000 0.5207 0.0740 0.8934

 

2000 10 0.4140 0.8545 1.1639 0.0000 1.2412 0.0217 0.0346 0.0000 0.0000 0.0013 0.0229

2000 11 0.8188 0.4195 1.5197 0.0000 1.1891 0.0201 0.0321 0.0000 0.0000 0.0008 0.0209

2000 12 0.4402 0.3805 1.5310 0.0000 1.1375 0.0198 0.0317 0.0000 0.0000 0.0004 0.0202

 

2001 1 0.4462 0.3488 1.4583 0.0000 1.0882 0.0190 0.0304 0.0000 0.0000 0.0000 0.0190

2001 2 0.9874 0.7255 1.8043 0.0000 1.0454 0.0164 0.0263 0.0000 0.0000 0.0007 0.0172

2001 3 1.6593 0.9326 2.4461 0.1030 1.1020 0.0179 0.0286 0.0442 0.0737 0.0053 0.0968

 

2001 4 2.8787 2.2631 2.5433 0.2195 1.2719 0.0191 0.0305 0.0843 0.3552 0.0035 0.3778

2001 5 3.2023 3.1134 1.9938 0.1972 1.4074 0.0237 0.0379 0.0118 0.5286 0.0067 0.5590

2001 6 0.8924 1.9418 0.9515 0.0004 1.3486 0.0228 0.0364 0.0001 0.0113 0.0049 0.0390

 

2001 7 3.0796 2.6060 1.4288 0.0000 1.2902 0.0225 0.0360 0.0000 0.0001 0.0190 0.0416

2001 8 2.5668 2.4852 1.5003 0.0000 1.2342 0.0215 0.0344 0.0000 0.0000 0.0171 0.0386

2001 9 1.3499 1.7694 1.0850 0.0000 1.1823 0.0199 0.0319 0.0000 0.0000 0.0068 0.0268

 

2001 18.7356 17.8404 1.0850 0.5200 1.1823 0.2444 0.3908 0.0000 0.9689 0.0665 1.2799

 

Period 60.014 51.785 1.085 2.127 1.182 0.748 1.197 0.000 5.172 0.254 6.174
ASSESSMENT OF WATER RESOURCES 101

Simulated intrawatershed results indicate that on 

a daily basis that there is very little water in the baseflow reservoir for metamorphic rocks and even less 

water in the intrusive rocks (table 29B and C). The 

median for daily values is substantially less than the 

daily mean. In fact, a time series of daily values for the 

contents of base-flow reservoir in the intrusive rocks is 

about zero 70 percent of the contemporary simulation 

period (70th percentile is 0.0002 inch). Under this 

condition, only ground water that is not associated with 

local streamflow is available for withdrawal by wells, 

and the volume of this water is unknown.

The summaries of GSNK in table 27 and 

table 28 indicate that, during contemporary simulations, about 0.15 to 0.40 inch of water may be lost 

from the base-flow reservoir at a watershed scale; 

Table 28. Intrawatershed summary statistics for contemporary simulations (January 1, 1999,

through September 30, 2001) for areas of A) metamorphic, (B) intrusive, and (C) fault-zone 

rocks and (D) Pikes Peak Granite—Continued

[Year, water year (October through September) if month not given; Mo, month; all numbers other 

 than dates in inches; Precip,total precipitation; ET, total evapotranspiration; sm, contents of 

 soil-zone reservoir at end of given period; bfi, total water added to base-flow reservoir;

 bfr, contents of base flow reservoir at end of accounting period; bf, total base flow 

 discharged to stream; gsnk, total water lost from base-flow reservoir that is not available to 

 support local streamflow; ir, contents of interflow reservoir at end of the accounting period; if, 

 total interflow; ovf, total overland flow; tf, total watershed flow]

-----------------------------------------------------------------------------------------------------

Year Mo Precip ET sm bfi bfr bf gsnk ir if ovf tf 

-----------------------------------------------------------------------------------------------------

 D. Pikes Peak Granite

1999 1 0.8800 0.2546 0.5785 0.0000 2.2955 0.0409 0.1636 0.0000 0.0000 0.0000 0.0409

1999 2 0.3400 0.5401 0.5454 0.0000 2.1252 0.0341 0.1362 0.0000 0.0000 0.0005 0.0346

1999 3 0.5100 0.7301 0.3342 0.0000 1.9514 0.0348 0.1390 0.0000 0.0000 0.0003 0.0350

 

1999 4 7.9400 0.7813 2.2006 0.4462 2.2395 0.0316 0.1264 0.0862 0.0218 0.0014 0.0549

1999 5 3.8900 2.8465 1.9117 4.2988 6.1873 0.0702 0.2809 0.6502 1.2291 0.0050 1.3043

1999 6 2.0900 3.3569 0.6584 0.1981 5.8822 0.1007 0.4025 0.0064 0.4458 0.0131 0.5595

 

1999 7 2.8700 1.4199 2.1004 0.0034 5.4043 0.0963 0.3850 0.0001 0.0043 0.0155 0.1161

1999 8 3.2900 3.1813 1.1349 0.7982 5.7055 0.0994 0.3976 0.0060 0.2615 0.0217 0.3827

1999 9 0.9500 1.1154 0.9506 0.0019 5.2551 0.0905 0.3618 0.0001 0.0041 0.0030 0.0975

 

1999 22.7600 14.2262 0.9506 5.7467 5.2551 0.5986 2.3930 0.0001 1.9665 0.0605 2.6256

 

1999 10 1.1900 1.2083 1.0084 0.0000 4.8253 0.0860 0.3438 0.0000 0.0000 0.0009 0.0869

1999 11 0.7300 0.6052 1.0115 0.0000 4.4429 0.0765 0.3059 0.0000 0.0000 0.0000 0.0765

1999 12 1.7000 0.4065 1.4734 0.0000 4.0795 0.0727 0.2907 0.0000 0.0000 0.0000 0.0727

 

2000 1 0.9500 0.4508 1.6178 0.0000 3.7458 0.0668 0.2669 0.0000 0.0000 0.0000 0.0668

2000 2 0.3300 1.0149 1.7452 0.0000 3.4584 0.0575 0.2299 0.0000 0.0000 0.0006 0.0581

2000 3 2.7900 0.9728 2.2233 0.2377 3.4099 0.0573 0.2289 0.0000 0.0000 0.0001 0.0574

 

2000 4 1.9700 2.1016 1.6749 1.4663 4.5304 0.0692 0.2766 0.0901 0.3105 0.0068 0.3865

2000 5 1.7600 2.9871 0.5684 0.0522 4.2083 0.0749 0.2994 0.0008 0.0607 0.0061 0.1418

2000 6 1.3500 1.1382 0.7668 0.0003 3.8750 0.0667 0.2668 0.0000 0.0005 0.0064 0.0737

 

2000 7 2.4100 2.5311 0.5864 0.0517 3.6077 0.0638 0.2552 0.0000 0.0000 0.0144 0.0783

2000 8 3.7800 2.4006 1.9649 0.0000 3.3126 0.0590 0.2360 0.0000 0.0000 0.0220 0.0811

2000 9 1.1300 1.9352 1.1528 0.0000 3.0501 0.0525 0.2100 0.0000 0.0000 0.0027 0.0552

 

2000 20.0900 17.7524 1.1528 1.8082 3.0501 0.8030 3.2102 0.0000 0.3718 0.0601 1.2348

 

2000 10 0.4300 0.7863 0.7838 0.0000 2.8006 0.0499 0.1995 0.0000 0.0000 0.0008 0.0507

2000 11 0.8300 0.3286 1.0953 0.0000 2.5786 0.0444 0.1776 0.0000 0.0000 0.0001 0.0445

2000 12 0.4500 0.2960 1.1370 0.0000 2.3677 0.0422 0.1687 0.0000 0.0000 0.0000 0.0422

 

2001 1 0.4800 0.2597 1.1141 0.0000 2.1741 0.0387 0.1549 0.0000 0.0000 0.0000 0.0387

2001 2 1.0600 0.5881 1.3660 0.0000 2.0128 0.0323 0.1290 0.0000 0.0000 0.0000 0.0323

2001 3 1.8000 0.7792 2.2019 0.2744 2.1174 0.0340 0.1358 0.0036 0.0041 0.0021 0.0401

 

2001 4 3.0800 2.0591 1.8216 1.7025 3.5914 0.0457 0.1827 0.1484 0.2713 0.0002 0.3173

2001 5 3.2300 2.9627 1.1669 0.7945 4.0449 0.0682 0.2728 0.0107 0.2931 0.0039 0.3653

2001 6 0.9100 1.7022 0.3852 0.0034 3.7275 0.0642 0.2566 0.0001 0.0072 0.0037 0.0751

 

2001 7 3.1400 2.8061 0.7339 0.0000 3.4227 0.0610 0.2439 0.0000 0.0001 0.0162 0.0773

2001 8 2.6700 2.3218 1.0760 0.0000 3.1428 0.0560 0.2239 0.0000 0.0000 0.0145 0.0705

2001 9 1.3700 1.8542 0.6053 0.0000 2.8937 0.0498 0.1993 0.0000 0.0000 0.0030 0.0528

 

2001 19.4500 16.7439 0.6053 2.7748 2.8937 0.5865 2.3447 0.0000 0.5758 0.0445 1.2068

 

Period 62.300 48.722 0.605 10.330 2.894 1.988 7.948 0.000 2.914 0.165 5.067

-----------------------------------------------------------------------------------------------------
102 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

this water is available for withdrawal by wells but 

is not available to support local streamflow. On an 

intra watershed scale, estimates for GSNK indicate 

that annual total accretions are in the tenths of an 

inch range for metamorphic-rock (0.21 inch), intrusive-rock (0.13 inch), and fault-zone reservoirs 

(0.44 inch) and are about 2.9 inches for the Pikes Peak 

Granite reservoir. The only accounting of GSNK available with PRMS concerns accretions; that is, PRMS 

provides no information describing how that water 

behaves, and a ground-water model is required for 

balance accounting of water that is not associated 

with streamflow. 

Long-Term Simulations

The slightly less than 3-year summaries available 

from the contemporary simulations provide a description 

of hydrologic conditions during varied climatic conditions; however, the contemporary simulations do not 

provide a description of how hydrologic conditions 

are likely to vary over a period of decades. In order to 

obtain estimates for a longer period of time, long-term 

simulations were undertaken. Climatologic data from 

Cheesman Reservoir, with minor adjustments to airtemperature data, were used to obtain the long-term 

simulations beginning October 1, 1948, and continuing 

through September 30, 1999, a period of 51 water years.

Table 29. Summary statistics of daily values for water-balance terms from contemporary simulations 

in (A) the entire Turkey Creek watershed and for areas of (B) metamorphic, (C) intrusive, and (D) fault-zone 

rocks and (E) Pikes Peak Granite

[All univariate statistics and percentiles reported in inches; Precip, total precipitation; ET, 

 total evapotranspiration; sm, contents of soil-zone reservoir at end of given period; bfi, 

 total water added to base-flow reservoir; bfr, contents of base-flow reservoir at end of 

 accounting period; bf, total base flow discharged to stream; gsnk, total water lost from 

 base-flow reservoir that is not available to support local streamflow; ir, contents of 

 interflow reservoir at end of the accounting period; if, total interflow; ovf, total overland 

 flow; tf, total watershed flow; Min, minimum; Max, maximum, Stddev, standard deviation; N, number 

 of observations; %, percentage] 

 A. Entire Turkey Creek watershed

 

 Univariate statistics 

-------------------------------------------------------------------- 

 

Variable Mean Median Stddev Min Max N 

-------- ------ ------ ------ ------ ------ ---- 

Precip 0.0571 0.0000 0.1519 0.0000 1.9331 1004

ET 0.0503 0.0365 0.0442 0.0000 0.1967 1004

sm 1.6867 1.5812 0.7650 0.1010 4.1275 1004

bfi 0.0027 0.0000 0.0126 0.0000 0.1582 1004

bfr 0.1776 0.1733 0.0523 0.1003 0.5031 1004

bf 0.0020 0.0002 0.0067 0.0001 0.0768 1004

gsnk 0.0007 0.0003 0.0017 0.0001 0.0195 1004

ir 0.0337 0.0020 0.1055 0.0000 0.8461 1004

if 0.0029 0.0001 0.0100 0.0000 0.0929 1004

ovf 0.0003 0.0000 0.0012 0.0000 0.0251 1004

tf 0.0052 0.0006 0.0164 0.0001 0.1568 1004

 

 Percentiles

----------------------------------------------------------------------------------------------

Variable 0.1% 1.0% 5.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 

-------- ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ 

bfr 0.1003 0.1012 0.1085 0.1171 0.1310 0.1471 0.1617 0.1733 0.1821 0.1963 0.2137 0.2402

ir 0.0000 0.0000 0.0000 0.0000 0.0001 0.0006 0.0012 0.0020 0.0037 0.0084 0.0209 0.0668

 Correlations 

----------------------------------------------------------------------------------------------------------

Variable Precip ET sm bfi bfr bf gsnk ir if ovf tf

-------- ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ 

Precip 1.0000 -0.0534 0.2206 0.3763 0.1295 0.2052 0.1856 0.2190 0.1583 0.8016 0.2396

ET -.0534 1.0000 0.5221 0.1058 0.4754 0.2131 0.2217 0.3329 0.3160 0.0685 0.2846

sm 0.2206 0.5221 1.0000 0.4646 0.7085 0.6031 0.6132 0.6303 0.6050 0.2393 0.6326

bfi 0.3763 0.1058 0.4646 1.0000 0.4516 0.8471 0.7982 0.6582 0.6140 0.4375 0.7522

bfr 0.1295 0.4754 0.7085 0.4516 1.0000 0.6170 0.6568 0.7302 0.7001 0.2107 0.6941

bf 0.2052 0.2131 0.6031 0.8471 0.6170 1.0000 0.9907 0.8559 0.8472 0.2353 0.9418

gsnk 0.1856 0.2217 0.6132 0.7982 0.6568 0.9907 1.0000 0.8768 0.8670 0.2038 0.9478

ir 0.2190 0.3329 0.6303 0.6582 0.7302 0.8559 0.8768 1.0000 0.9860 0.3094 0.9732

if 0.1583 0.3160 0.6050 0.6140 0.7001 0.8472 0.8670 0.9860 1.0000 0.2307 0.9724

ovf 0.8016 0.0685 0.2393 0.4375 0.2107 0.2353 0.2038 0.3094 0.2307 1.0000 0.3108

tf 0.2396 0.2846 0.6326 0.7522 0.6941 0.9418 0.9478 0.9732 0.9724 0.3108 1.0000
ASSESSMENT OF WATER RESOURCES 103

The same model characterization of the watershed 

used for the contemporary simulations, which is based 

on streamflow data that reflect contemporary water use, 

was used for the long-term simulations. Water use in the 

watershed is largely a function of population, and the 

contemporary amount of ground water withdrawn for 

use is likely much greater than withdrawals made near 

the beginning of the long-term simulation period. Consequently, the long-term simulations indicate how the 

Turkey Creek watershed might respond to the 51 years 

of precipitation and temperature data used to derive the 

long-term simulations under current conditions of water 

use and not under historical conditions of water use. 

Results from the long-term simulations are 

listed in table 30, table 31, and table 32 and are 

shown in figure 45. The long-term simulations indicate 

intrawatershed daily central tendencies are slightly 

higher but similar to contemporary simulation estimates. There is a possibility that the long-term estimates have bias due to the use of precipitation and 

temperature data from outside the watershed; however, 

the magnitude of Cheesman annual totals for precipitation is certainly similar to that measured in the 

Turkey Creek watershed during this study, and the 

Cheesman data seem to be a reasonable surrogate. 

Also, the important contribution of long-term

Table 29. Summary statistics of daily values for water-balance terms from contemporary simulations 

in (A) the entire Turkey Creek watershed and areas of (B) metamorphic, (C) intrusive, and (D) fault-zone 

rocks and (E) Pikes Peak Granite—Continued

[All univariate statistics and percentiles reported in inches; Precip, total precipitation; ET, 

 total evapotranspiration; sm, contents of soil-zone reservoir at end of given period; bfi, 

 total water added to base-flow reservoir; bfr, contents of base-flow reservoir at end of 

 accounting period; bf, total base flow discharged to stream; gsnk, total water lost from 

 base-flow reservoir that is not available to support local streamflow; ir, contents of 

 interflow reservoir at end of the accounting period; if, total interflow; ovf, total overland 

 flow; tf, total watershed flow; Min, minimum; Max, maximum, Stddev, standard deviation; N, number 

 of observations; %, percentage] 

 B. Metamorphic rocks

 Univariate statistics 

-------------------------------------------------------------------- 

 

Variable Mean Median Stddev Min Max N 

-------- ------ ------ ------ ------ ------ ---- 

Precip 0.0561 0.0000 0.1525 0.0000 2.0688 1004

ET 0.0503 0.0367 0.0443 0.0000 0.1994 1004

sm 1.6818 1.5825 0.7744 0.1014 4.3055 1004

bfi 0.0022 0.0000 0.0125 0.0000 0.1716 1004

bfr 0.0128 0.0009 0.0461 0.0000 0.5294 1004

bf 0.0016 0.0001 0.0060 0.0000 0.0684 1004

gsnk 0.0006 0.0000 0.0021 0.0000 0.0244 1004

ir 0.0406 0.0029 0.1231 0.0000 0.9904 1004

if 0.0026 0.0001 0.0086 0.0000 0.0763 1004

ovf 0.0003 0.0000 0.0013 0.0000 0.0246 1004

tf 0.0045 0.0005 0.0145 0.0000 0.1473 1004

 

 Percentiles

----------------------------------------------------------------------------------------------

Variable 0.1% 1.0% 5.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 

-------- ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ 

bfr 0.0000 0.0000 0.0000 0.0000 0.0000 0.0001 0.0003 0.0009 0.0021 0.0040 0.0077 0.0226

ir 0.0000 0.0000 0.0000 0.0000 0.0002 0.0007 0.0015 0.0029 0.0050 0.0097 0.0256 0.0803

 

 Correlations 

----------------------------------------------------------------------------------------------------------

Variable Precip ET sm bfi bfr bf gsnk ir if ovf tf

-------- ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ 

Precip 1.0000 -0.0435 0.2267 0.3994 0.1661 0.1661 0.1661 0.1966 0.1372 0.8226 0.2213

ET -.0435 1.0000 0.5314 0.0451 0.2056 0.2056 0.2056 0.3417 0.3136 0.0665 0.2765

sm 0.2267 0.5314 1.0000 0.4138 0.6063 0.6063 0.6063 0.6469 0.6172 0.2520 0.6373

bfi 0.3994 0.0451 0.4138 1.0000 0.7132 0.7132 0.7132 0.5819 0.5450 0.4605 0.6563

bfr 0.1661 0.2056 0.6063 0.7132 1.0000 1.0000 1.0000 0.8788 0.8958 0.1902 0.9589

bf 0.1661 0.2056 0.6063 0.7132 1.0000 1.0000 1.0000 0.8788 0.8958 0.1902 0.9589

gsnk 0.1661 0.2056 0.6063 0.7132 1.0000 1.0000 1.0000 0.8788 0.8958 0.1902 0.9589

ir 0.1966 0.3417 0.6469 0.5819 0.8788 0.8788 0.8788 1.0000 0.9902 0.2828 0.9734

if 0.1372 0.3136 0.6172 0.5450 0.8958 0.8958 0.8958 0.9902 1.0000 0.2032 0.9793

ovf 0.8226 0.0665 0.2520 0.4605 0.1902 0.1902 0.1902 0.2828 0.2032 1.0000 0.2858

tf 0.2213 0.2765 0.6373 0.6563 0.9589 0.9589 0.9589 0.9734 0.9793 0.2858 1.0000
104 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

simulations is not an exact duplication of watershed 

climatologic conditions; rather, it is an evaluation of 

how ground-water conditions are likely to vary during 

a period of several decades of climatic conditions 

that are at least similar to climate conditions in the 

watershed. 

The long-term estimates reiterate that the watershed contents of the base-flow reservoirs fluctuate 

seasonally. The watershed representation of base-flow 

reservoir contents (fig. 45) indicates that recharge to 

watershed base-flow reservoir can result in net end-ofyear increases of about 0.1 inch (1957, 1969, 1973, 

and 1995, table 30) and that these increases have a 

tendency to persist for years. However, during periods 

with relatively small amounts of precipitation, 

simulated results indicate that, on a watershed scale, 

the contents of the base-flow reservoirs may recede 

to less than one-tenth of an inch (for example, 1954 

and 1956 in table 30). Relatively large annual changes 

in the contents of the base-flow reservoir are associated with relatively large amounts of ground-water 

recharge to the watershed. For instance, in water 

year 1973 the simulated results indicate that the 

watershed base-flow reservoir received nearly 5 inches 

of recharge in the spring (bfi of 4.8 inches in 1973, 

table 30) and that this amount of recharge resulted in 

a 0.13-inch increase in watershed base-flow reservoir 

contents at the end of water year 1973 compared to 

water year 1972 (table 30). In contrast, during water 

year 1954, the simulated results indicate a low amount

Table 29. Summary statistics of daily values for water-balance terms from contemporary simulations 

in (A) the entire Turkey Creek watershed and areas of (B) metamorphic, (C) intrusive, and (D) fault-zone 

rocks and (E) Pikes Peak Granite—Continued

[All univariate statistics and percentiles reported in inches; Precip, total precipitation; ET, 

 total evapotranspiration; sm, contents of soil-zone reservoir at end of given period; bfi, 

 total water added to base-flow reservoir; bfr, contents of base-flow reservoir at end of 

 accounting period; bf, total base flow discharged to stream; gsnk, total water lost from 

 base-flow reservoir that is not available to support local streamflow; ir, contents of 

 interflow reservoir at end of the accounting period; if, total interflow; ovf, total overland 

 flow; tf, total watershed flow; Min, minimum; Max, maximum, Stddev, standard deviation; N, number 

 of observations; %, percentage] 

 C. Intrusive rocks

 

 Univariate statistics 

-------------------------------------------------------------------- 

Variable Mean Median Stddev Min Max N 

-------- ------ ------ ------ ------ ------ ---- 

Precip 0.0582 0.0000 0.1534 0.0000 2.0937 1004

ET 0.0506 0.0375 0.0451 0.0000 0.2066 1004

sm 1.7451 1.6427 0.7869 0.0997 4.0257 1004

bfi 0.0036 0.0000 0.0153 0.0000 0.1665 1004

bfr 0.0029 0.0000 0.0105 0.0000 0.1111 1004

bf 0.0032 0.0000 0.0118 0.0000 0.1248 1004

gsnk 0.0004 0.0000 0.0013 0.0000 0.0137 1004

ir 0.0184 0.0002 0.0752 0.0000 0.9416 1004

if 0.0030 0.0000 0.0122 0.0000 0.1505 1004

ovf 0.0003 0.0000 0.0012 0.0000 0.0286 1004

tf 0.0065 0.0002 0.0226 0.0000 0.2140 1004

 

 Percentiles

----------------------------------------------------------------------------------------------

Variable 0.1% 1.0% 5.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 

-------- ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ 

bfr 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0002 0.0012 0.0052

ir 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0002 0.0006 0.0018 0.0057 0.0280

 

 Correlations 

----------------------------------------------------------------------------------------------------------

Variable Precip ET sm bfi bfr bf gsnk ir if ovf tf

-------- ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ 

Precip 1.0000 -0.0517 0.2109 0.3268 0.2470 0.2470 0.2470 0.2781 0.1827 0.7642 0.2687

ET -.0517 1.0000 0.5203 0.1434 0.1921 0.1921 0.1921 0.2587 0.2752 0.0756 0.2520

sm 0.2109 0.5203 1.0000 0.4675 0.5474 0.5474 0.5474 0.5377 0.5351 0.2188 0.5844

bfi 0.3268 0.1434 0.4675 1.0000 0.9426 0.9426 0.9426 0.6787 0.6013 0.3904 0.8349

bfr 0.2470 0.1921 0.5474 0.9426 1.0000 1.0000 1.0000 0.7645 0.7266 0.2746 0.9258

bf 0.2470 0.1921 0.5474 0.9426 1.0000 1.0000 1.0000 0.7645 0.7266 0.2746 0.9258

gsnk 0.2470 0.1921 0.5474 0.9426 1.0000 1.0000 1.0000 0.7645 0.7266 0.2746 0.9258

ir 0.2781 0.2587 0.5377 0.6787 0.7645 0.7645 0.7645 1.0000 0.9788 0.4026 0.9460

if 0.1827 0.2752 0.5351 0.6013 0.7266 0.7266 0.7266 0.9788 1.0000 0.2616 0.9299

ovf 0.7642 0.0756 0.2188 0.3904 0.2746 0.2746 0.2746 0.4026 0.2616 1.0000 0.3385

tf 0.2687 0.2520 0.5844 0.8349 0.9258 0.9258 0.9258 0.9460 0.9299 0.3385 1.0000
ASSESSMENT OF WATER RESOURCES 105

of recharge to the watershed base-flow reservoir 

(0.0326 inch) resulting in an-end-of-year reduction of 

about 0.06 inch compared to 1953. In the 51 years of 

long-term simulations, several consecutive years with 

low amounts of precipitation and recharge similar to 

1954, a year with relatively small amounts of water in 

base-flow reservoirs, did not occur. Several consecutive years with low amounts of precipitation and 

recharge similar to 1954 (or 1964, 1966, 1986, 1989, 

and so forth), however, would deplete ground-water 

available to support base flow in the Turkey Creek 

watershed, and the period of 1966 through 1968 gives 

some indication of this. The temporal pattern of 

precipitation described by the 51 years of Cheesman 

data indicates that several consecutive years of low 

precipitation (10 to 14 inches) did not occur in that 

record. However, global- or regional-scale climate 

changes or cycles could have a significant effect on the 

water supply in the Turkey Creek watershed. 

Intrawatershed conditions described by the 

long-term simulations (table 31, table 32, and fig. 45) 

reiterate many of the observations discussed in the 

“Contemporary Simulations” section, particularly 

those concerning differences between the reservoirs 

and the dynamic nature of the interflow reservoirs. For 

the entire long-term simulation period, the simulation 

results indicate that the end-of-year contents of the 

base-flow reservoir was zero about 60 percent of the 

period in the intrusive rocks and about 30 percent of 

the period in the metamorphic rocks. In contrast, in

Table 29. Summary statistics of daily values for water-balance terms from contemporary simulations 

in (A) the entire Turkey Creek watershed and areas of (B) metamorphic, (C) intrusive, and (D) fault-zone 

rocks and (E) Pikes Peak Granite—Continued

[All univariate statistics and percentiles reported in inches; Precip, total precipitation; ET, 

 total evapotranspiration; sm, contents of soil-zone reservoir at end of given period; bfi, 

 total water added to base-flow reservoir; bfr, contents of base-flow reservoir at end of 

 accounting period; bf, total base flow discharged to stream; gsnk, total water lost from 

 base-flow reservoir that is not available to support local streamflow; ir, contents of 

 interflow reservoir at end of the accounting period; if, total interflow; ovf, total overland 

 flow; tf, total watershed flow; Min, minimum; Max, maximum, Stddev, standard deviation; N, number 

 of observations; %, percentage] 

 D. Fault-zone rocks

 

 Univariate statistics 

-------------------------------------------------------------------- 

Variable Mean Median Stddev Min Max N 

-------- ------ ------ ------ ------ ------ ---- 

Precip 0.0598 0.0000 0.1636 0.0000 1.9336 1004

ET 0.0516 0.0387 0.0448 0.0000 0.2049 1004

sm 1.6979 1.5644 0.7570 0.1005 3.7985 1004

bfi 0.0021 0.0000 0.0081 0.0000 0.0678 1004

bfr 1.3531 1.3748 0.2569 0.8544 1.8292 1004

bf 0.0007 0.0008 0.0001 0.0005 0.0010 1004

gsnk 0.0012 0.0012 0.0002 0.0008 0.0016 1004

ir 0.0299 0.0000 0.1002 0.0000 1.0888 1004

if 0.0052 0.0000 0.0182 0.0000 0.2111 1004

ovf 0.0003 0.0000 0.0010 0.0000 0.0219 1004

tf 0.0061 0.0009 0.0185 0.0005 0.2120 1004

 

 Percentiles

----------------------------------------------------------------------------------------------

Variable 0.1% 1.0% 5.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 

-------- ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ 

bfr 0.8544 0.8606 0.9076 0.9739 1.1070 1.2114 1.2883 1.3748 1.4219 1.4916 1.5879 1.7237

ir 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0001 0.0016 0.0121 0.0672

 

 Correlations 

----------------------------------------------------------------------------------------------------------

Variable Precip ET sm bfi bfr bf gsnk ir if ovf tf

-------- ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ 

Precip 1.0000 -0.0706 0.1847 0.1958 0.0050 0.0049 0.0050 0.1886 0.1327 0.7133 0.1712

ET -.0706 1.0000 0.4655 0.2095 0.4194 0.4195 0.4194 0.3039 0.2972 0.0873 0.3011

sm 0.1847 0.4655 1.0000 0.5384 0.3868 0.3868 0.3869 0.6120 0.5868 0.2004 0.5928

bfi 0.1958 0.2095 0.5384 1.0000 0.0383 0.0383 0.0383 0.7720 0.7068 0.2848 0.7132

bfr 0.0050 0.4194 0.3868 0.0383 1.0000 1.0000 1.0000 0.1548 0.1595 0.1327 0.1724

bf 0.0049 0.4195 0.3868 0.0383 1.0000 1.0000 1.0000 0.1547 0.1594 0.1326 0.1723

gsnk 0.0050 0.4194 0.3869 0.0383 1.0000 1.0000 1.0000 0.1549 0.1595 0.1328 0.1724

ir 0.1886 0.3039 0.6120 0.7720 0.1548 0.1547 0.1549 1.0000 0.9830 0.2894 0.9866

if 0.1327 0.2972 0.5868 0.7068 0.1595 0.1594 0.1595 0.9830 1.0000 0.2014 0.9984

ovf 0.7133 0.0873 0.2004 0.2848 0.1327 0.1326 0.1328 0.2894 0.2014 1.0000 0.2562

tf 0.1712 0.3011 0.5928 0.7132 0.1724 0.1723 0.1724 0.9866 0.9984 0.2562 1.0000
106 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

areas of fault-zone rocks and Pikes Peak Granite, baseflow reservoirs contained water through the entire 

long-term simulation. During water year 1954, simulation results indicate that for 75 percent of the time, the 

contents of the intrusive-rock base-flow reservoir were 

insufficient to support base flow. 

Simulation Results and Their Implications 

to Water Supply

In order to give simulated results context with 

respect to water-supply issues, some discussion of 

water use in the watershed is required. It is important to note that, in this report, the term “water use” 

indicates the amount of water withdrawn from 

wells; it does not describe consumption or the 

amount of withdrawn water that is returned to the 

hydrologic system, but simply describes the amount 

of water required to satisfy estimated withdrawals 

from wells. It also is important to note that the 

PRMS watershed characterization is for the current 

conditions of water use—that is, the effects of 

current estimated withdrawals, whether they be 

depleted streamflow in some areas or a steady but 

small contribution of return flow to streamflow in 

other areas, are characterized by the calibrated 

model.

Table 29. Summary statistics of daily values for water-balance terms from contemporary simulations 

in (A) the entire Turkey Creek watershed and areas of (B) metamorphic, (C) intrusive, and (D) fault-zone 

rocks and (E) Pikes Peak Granite—Continued

[All univariate statistics and percentiles reported in inches; Precip, total precipitation; ET, 

 total evapotranspiration; sm, contents of soil-zone reservoir at end of given period; bfi, 

 total water added to base-flow reservoir; bfr, contents of base-flow reservoir at end of 

 accounting period; bf, total base flow discharged to stream; gsnk, total water lost from 

 base-flow reservoir that is not available to support local streamflow; ir, contents of 

 interflow reservoir at end of the accounting period; if, total interflow; ovf, total overland 

 flow; tf, total watershed flow; Min, minimum; Max, maximum, Stddev, standard deviation; N, number 

 of observations; %, percentage] 

 E. Pikes Peak Granite

 

 Univariate statistics 

-------------------------------------------------------------------- 

Variable Mean Median Stddev Min Max N 

-------- ------ ------ ------ ------ ------ ---- 

Precip 0.0621 0.0000 0.1739 0.0000 2.0000 1004

ET 0.0485 0.0340 0.0446 0.0000 0.2198 1004

sm 1.1442 1.0945 0.5601 0.0999 2.2431 1004

bfi 0.0103 0.0000 0.0380 0.0000 0.2431 1004

bfr 3.5904 3.5092 1.1735 1.8166 6.2116 1004

bf 0.0020 0.0019 0.0006 0.0010 0.0034 1004

gsnk 0.0079 0.0077 0.0026 0.0040 0.0137 1004

ir 0.0264 0.0000 0.0926 0.0000 1.0021 1004

if 0.0029 0.0000 0.0106 0.0000 0.1175 1004

ovf 0.0002 0.0000 0.0007 0.0000 0.0079 1004

tf 0.0050 0.0021 0.0109 0.0010 0.1208 1004

 

 Percentiles

----------------------------------------------------------------------------------------------

Variable 0.1% 1.0% 5.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 

-------- ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ 

bfr 1.8167 1.8625 1.9754 2.1071 2.3857 2.8433 3.2394 3.5092 3.7769 4.1063 4.5168 5.5073

ir 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0002 0.0066 0.0750

 

 Correlations 

----------------------------------------------------------------------------------------------------------

Variable Precip ET sm bfi bfr bf gsnk ir if ovf tf

-------- ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ 

Precip 1.0000 -0.0552 0.1860 0.1534 0.0218 0.0218 0.0218 0.1558 0.1133 0.5630 0.1461

ET -.0552 1.0000 0.3359 0.2773 0.3894 0.3894 0.3894 0.3461 0.3417 0.1519 0.3649

sm 0.1860 0.3359 1.0000 0.4697 0.0365 0.0365 0.0365 0.4097 0.3877 0.1467 0.3883

bfi 0.1534 0.2773 0.4697 1.0000 0.0932 0.0932 0.0932 0.6770 0.6134 0.1242 0.6099

bfr 0.0218 0.3894 0.0365 0.0932 1.0000 1.0000 1.0000 0.2957 0.3001 0.1607 0.3611

bf 0.0218 0.3894 0.0365 0.0932 1.0000 1.0000 1.0000 0.2957 0.3000 0.1607 0.3611

gsnk 0.0218 0.3894 0.0365 0.0932 1.0000 1.0000 1.0000 0.2957 0.3001 0.1607 0.3611

ir 0.1558 0.3461 0.4097 0.6770 0.2957 0.2957 0.2957 1.0000 0.9887 0.1087 0.9860

if 0.1133 0.3417 0.3877 0.6134 0.3001 0.3000 0.3001 0.9887 1.0000 0.0883 0.9960

ovf 0.5630 0.1519 0.1467 0.1242 0.1607 0.1607 0.1607 0.1087 0.0883 1.0000 0.1569

tf 0.1461 0.3649 0.3883 0.6099 0.3611 0.3611 0.3611 0.9860 0.9960 0.1569 1.0000

----------------------------------------------------------------------------------------------------------- 
ASSESSMENT OF WATER RESOURCES 107

10

8

SIMULATED CONTENTS OF BASE-FLOW RESERVOIR, IN INCHES 6

4

2

0

10

8

SIMULATED FLOW, IN INCHES

SIMULATED CONTENTS, IN INCHES

6

1.0

1.5

0.5

0

4

2

0

1940 1950 1960 1970 1980 1990 2000

Metamorphic rocks

Intrusive rocks

Base flow

Contents of base-flow

 reservoir

Fault-zone rocks

Pikes Peak Granite

Figure 45. Watershed hydrographs of long-term simulated results.
108 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

Table 30. Annual summary statistics for long-term simulations (October 1, 1948, through 

September 30, 1999) in the entire Turkey Creek watershed

[Year, water year (October through September) if month not given; all numbers other than dates 

 in inches; Precip,total precipitation; ET, total evapotranspiration; sm, contents of soil-zone 

 reservoir at end of given period; bfi, total water added to base-flow reservoir; 

 bfr, contents of base-flow reservoir at end of accounting period; bf, total base flow 

 discharged to stream; gsnk, total water lost from base-flow reservoir that is not available to 

 support local streamflow; ir, contents of interflow reservoir at end of the accounting period; 

 if, total interflow; ovf, total overland flow; tf, total watershed flow; Period, October 1948 

 through September 1999; Stddev, standard deviation] 

--------------------------------------------------------------------------------------------------

Year Precip ET sm bfi bfr bf gsnk ir if ovf tf 

--------------------------------------------------------------------------------------------------

1949 17.8100 14.8424 1.0834 1.0608 0.1592 0.7703 0.2540 0.0008 0.7694 0.1539 1.6936

1950 15.4800 14.2829 1.8669 0.1842 0.1078 0.1455 0.0901 0.0002 0.1210 0.1171 0.3837

 

1951 16.1600 15.9972 1.5394 0.1939 0.0845 0.1439 0.0733 0.0021 0.1733 0.1215 0.4386

1952 16.4800 15.1492 1.0960 0.8388 0.1079 0.6141 0.2014 0.0004 0.7991 0.1380 1.5512

1953 15.8100 14.4223 1.1399 0.6713 0.1216 0.4861 0.1714 0.0014 0.5464 0.1251 1.1575

1954 14.3700 13.5221 1.8561 0.0326 0.0628 0.0422 0.0492 0.0007 0.0080 0.0919 0.1421

1955 18.9600 16.6918 2.6239 0.6097 0.0945 0.4388 0.1392 0.0089 0.7257 0.1596 1.3241

 

1956 10.8200 12.4705 0.7423 0.1588 0.0604 0.1286 0.0643 0.0001 0.0291 0.0519 0.2096

1957 20.3200 15.0575 1.7577 2.8262 0.1861 2.0980 0.6026 0.0007 1.3382 0.0823 3.5185

1958 16.2100 13.7188 1.7741 1.7562 0.2017 1.3229 0.4177 0.0002 0.6462 0.0751 2.0442

1959 15.5600 12.8770 1.6515 0.5667 0.1645 0.4297 0.1742 0.0000 0.1520 0.0403 0.6220

1960 13.8100 12.9504 1.2537 2.0285 0.2108 1.5135 0.4687 0.0002 1.2096 0.0628 2.7859

 

1961 21.8700 17.1816 4.0647 0.8363 0.2519 0.5778 0.2174 0.2313 0.6024 0.1833 1.3636

1962 12.3100 13.2939 0.8715 1.8401 0.2169 1.4136 0.4616 0.0000 0.5431 0.0815 2.0382

1963 16.5600 12.6139 3.5017 0.7413 0.2140 0.5436 0.2006 0.0592 0.3970 0.1183 1.0589

1964 12.8700 13.9985 1.2121 0.7810 0.1586 0.6101 0.2264 0.0003 0.3805 0.0584 1.0489

1965 19.2600 14.6259 3.8883 0.7968 0.2039 0.5580 0.1935 0.0246 0.9593 0.1079 1.6251

 

1966 14.8200 16.4096 1.8093 0.4180 0.1325 0.3410 0.1484 0.0004 0.1049 0.0732 0.5191

1967 17.3500 15.8643 2.2572 0.5857 0.1413 0.4239 0.1530 0.0060 0.3496 0.1063 0.8798

1968 14.6400 14.2937 1.8811 0.5406 0.1131 0.4164 0.1525 0.0002 0.1203 0.0672 0.6039

1969 21.4100 17.8092 2.1982 2.2350 0.2352 1.6310 0.4819 0.0187 0.9170 0.1131 2.6612

1970 24.8000 17.2910 3.0678 3.5950 0.3222 2.6789 0.8290 0.0087 2.5549 0.0988 5.3325

 

1971 17.7900 15.4349 3.1556 1.2837 0.2902 0.9546 0.3611 0.0111 0.9437 0.0947 1.9930

1972 15.2500 15.5602 2.0735 0.6369 0.2160 0.4938 0.2173 0.0018 0.4246 0.0706 0.9890

1973 21.1600 13.2252 1.9331 4.8144 0.3513 3.5964 1.0826 0.0021 3.1741 0.0258 6.7964

1974 16.2200 14.9049 1.5347 1.3222 0.2694 1.0196 0.3844 0.0004 0.3981 0.0575 1.4752

1975 14.9700 13.8164 1.3864 0.6402 0.2106 0.4856 0.2135 0.0006 0.5361 0.1257 1.1474

 

1976 17.4600 14.4133 2.6852 1.1412 0.2158 0.8503 0.2858 0.0032 0.4873 0.0829 1.4205

1977 16.6700 15.9640 1.6972 1.2563 0.2209 0.9315 0.3197 0.0031 0.3767 0.0949 1.4031

1978 12.0300 12.0319 1.1773 0.3297 0.1460 0.2679 0.1367 0.0000 0.1456 0.0516 0.4651

1979 18.2900 13.5406 1.5866 2.7104 0.2233 2.0245 0.6087 0.0012 1.5719 0.0566 3.6530

1980 16.2500 12.7524 1.2852 2.3212 0.2333 1.7544 0.5568 0.0005 1.4412 0.0391 3.2347

 

1981 16.0800 15.2965 1.6630 0.1908 0.1566 0.1592 0.1083 0.0012 0.1257 0.0885 0.3734

1982 22.7100 17.5638 4.0935 1.4678 0.2531 1.0482 0.3232 0.0468 1.0050 0.1722 2.2253

1983 19.1300 16.4440 1.2197 3.5384 0.2738 2.6895 0.8282 0.0015 2.0279 0.0642 4.7816

1984 20.3300 16.0775 2.3888 1.5975 0.2602 1.1938 0.4174 0.0435 1.3184 0.1132 2.6254

1985 18.8900 14.6430 2.9654 1.8458 0.2657 1.3773 0.4630 0.0111 1.7003 0.1336 3.2112

 

1986 14.7100 15.2895 1.9256 0.3230 0.1756 0.2624 0.1507 0.0000 0.0832 0.0664 0.4120

1987 20.4200 15.7246 2.3205 2.8423 0.2618 2.1189 0.6371 0.0043 1.3637 0.1259 3.6085

1988 17.9400 16.3684 1.8819 1.4449 0.2363 1.0974 0.3730 0.0011 0.4868 0.0886 1.6728

1989 13.3600 13.5294 1.4865 0.1395 0.1389 0.1323 0.1046 0.0000 0.0307 0.0593 0.2223

1990 20.2600 15.4614 3.2642 2.0685 0.2174 1.5336 0.4564 0.0420 0.8214 0.0987 2.4537

 

1991 19.0400 16.9214 2.0042 2.0075 0.2685 1.4839 0.4725 0.0061 1.2420 0.1575 2.8834

1992 18.6100 16.2061 2.3118 1.4903 0.2617 1.1191 0.3779 0.0088 0.4962 0.1165 1.7318

1993 13.9900 12.2698 2.5285 0.9811 0.2064 0.7558 0.2807 0.0003 0.4585 0.0582 1.2725

1994 17.4700 15.4472 2.0278 1.7778 0.2372 1.3271 0.4200 0.0006 0.6785 0.0811 2.0866

1995 21.0700 14.6562 2.1259 3.9598 0.3520 2.9602 0.8848 0.0024 2.2682 0.0919 5.3203

 

1996 13.5700 12.1850 3.2405 0.1581 0.2181 0.1500 0.1419 0.0023 0.0170 0.0582 0.2251

1997 17.2500 15.8144 2.9695 1.1532 0.2272 0.8577 0.2864 0.0093 0.4708 0.1143 1.4428

1998 18.7600 15.2250 1.9283 2.9850 0.2869 2.2356 0.6898 0.0055 1.4971 0.0855 3.8182

1999 16.5100 13.8897 1.9609 1.6961 0.2697 1.2805 0.4328 0.0009 0.8369 0.0731 2.1905

 

Period 873.869 756.020 1.961 71.421 0.270 53.489 17.786 0.001 39.874 4.774 98.137

Mean 17.1347 14.8239 2.0776 1.4004 0.2058 1.0488 0.3487 0.0113 0.7819 0.0936 1.9243

Median 16.6700 14.9049 1.9256 1.1532 0.2160 0.8577 0.2864 0.0014 0.5464 0.0886 1.5512

Min 10.8200 12.0319 0.7423 0.0326 0.0604 0.0422 0.0492 0.0000 0.0080 0.0258 0.1421

Max 24.8000 17.8092 4.0935 4.8144 0.3520 3.5964 1.0826 0.2313 3.1741 0.1833 6.7964

Stddev 2.9366 1.5033 0.8159 1.0990 0.0693 0.8193 0.2328 0.0341 0.6910 0.0358 1.4792

-----------------------------------------------------------------------------------------------------
ASSESSMENT OF WATER RESOURCES 109

Table 31. Intrawatershed summary statistics for long-term simulations (October 1, 1948, through 

September 30, 1999) for areas of (A) metamorphic, (B) intrusive, and (C) fault-zone rocks and 

(D) Pikes Peak Granite in the Turkey Creek watershed

[Year, water year (October through September) if month not given; all numbers other than dates 

 in inches; Precip,total precipitation; ET, total evapotranspiration; sm, contents of soil-zone 

 reservoir at end of given period; bfi, total water added to base-flow reservoir; 

 bfr, contents of base-flow reservoir at end of accounting period; bf, total base flow 

 discharged to stream; gsnk, total water lost from base-flow reservoir that is not available to 

 support local streamflow; ir, contents of interflow reservoir at end of the accounting period; 

 if, total interflow; ovf, total overland flow; tf, total watershed flow; Period, October 1948 

 through September 1999; Stddev, standard deviation] 

-----------------------------------------------------------------------------------------------------

Year Precip ET sm bfi bfr bf gsnk ir if ovf tf 

-----------------------------------------------------------------------------------------------------

 A. Metamorphic rocks

1949 17.8100 15.1796 1.1185 0.9216 0.0000 0.6804 0.2422 0.0012 0.5832 0.1571 1.4207

1950 15.4800 14.4009 1.8976 0.1266 0.0001 0.0933 0.0332 0.0004 0.0794 0.1186 0.2913

 

1951 16.1600 16.1696 1.5712 0.1345 0.0000 0.0993 0.0353 0.0032 0.1084 0.1232 0.3309

1952 16.4800 15.4523 1.1053 0.7665 0.0000 0.5653 0.2012 0.0006 0.6378 0.1404 1.3435

1953 15.8100 14.6875 1.1750 0.5699 0.0000 0.4203 0.1496 0.0022 0.4140 0.1272 0.9615

1954 14.3700 13.5946 1.8581 0.0343 0.0024 0.0236 0.0084 0.0008 0.0088 0.0933 0.1256

1955 18.9600 17.0103 2.6662 0.5238 0.0012 0.3871 0.1378 0.0134 0.5085 0.1617 1.0574

 

1956 10.8200 12.5624 0.7538 0.1217 0.0000 0.0907 0.0323 0.0001 0.0263 0.0533 0.1703

1957 20.3200 15.3751 1.8047 2.7708 0.0000 2.0434 0.7274 0.0011 1.1109 0.0888 3.2431

1958 16.2100 14.1265 1.8096 1.6069 0.0002 1.1849 0.4218 0.0003 0.4575 0.0808 1.7232

1959 15.5600 13.1321 1.7535 0.4218 0.0000 0.3112 0.1108 0.0001 0.0986 0.0440 0.4537

1960 13.8100 13.3507 1.2731 1.9015 0.0000 1.4023 0.4992 0.0003 0.9935 0.0696 2.4654

 

1961 21.8700 17.5520 4.1836 0.6397 0.0600 0.4276 0.1522 0.2710 0.3529 0.1849 0.9654

1962 12.3100 13.6891 0.8872 1.6743 0.0000 1.2790 0.4553 0.0000 0.4898 0.0844 1.8532

1963 16.5600 12.7949 3.6051 0.6306 0.0261 0.4458 0.1587 0.0842 0.2731 0.1207 0.8396

1964 12.8700 14.2860 1.2311 0.7093 0.0000 0.5424 0.1931 0.0005 0.3084 0.0603 0.9110

1965 19.2600 14.9772 4.0006 0.6278 0.0369 0.4358 0.1551 0.0310 0.7825 0.1123 1.3306

 

1966 14.8200 16.6013 1.8495 0.3228 0.0000 0.2653 0.0944 0.0007 0.0739 0.0749 0.4140

1967 17.3500 16.1512 2.3042 0.4489 0.0000 0.3310 0.1179 0.0093 0.2336 0.1094 0.6740

1968 14.6400 14.4770 1.9021 0.4525 0.0000 0.3337 0.1188 0.0003 0.0768 0.0696 0.4801

1969 21.4100 18.3137 2.2538 1.9694 0.0001 1.4523 0.5170 0.0285 0.7099 0.1166 2.2789

1970 24.8000 17.7706 3.2288 3.6119 0.0084 2.6576 0.9461 0.0126 2.1632 0.1041 4.9249

 

1971 17.7900 15.8800 3.2733 1.0844 0.0091 0.7992 0.2845 0.0142 0.7462 0.0994 1.6448

1972 15.2500 15.8849 2.0722 0.4816 0.0002 0.3618 0.1288 0.0026 0.3277 0.0735 0.7629

1973 21.1600 13.2141 1.9690 4.9651 0.0031 3.6595 1.3028 0.0032 3.0783 0.0278 6.7656

1974 16.2200 15.0927 1.5593 1.2100 0.0000 0.8946 0.3185 0.0006 0.3353 0.0600 1.2898

1975 14.9700 14.1514 1.4149 0.4708 0.0000 0.3472 0.1236 0.0010 0.3858 0.1263 0.8592

 

1976 17.4600 14.8383 2.7398 0.9339 0.0042 0.6856 0.2441 0.0035 0.3065 0.0877 1.0798

1977 16.6700 16.3392 1.7323 1.0664 0.0002 0.7894 0.2810 0.0047 0.2279 0.0986 1.1159

1978 12.0300 12.2027 1.1920 0.2495 0.0000 0.1841 0.0655 0.0000 0.0930 0.0530 0.3301

1979 18.2900 13.7639 1.6169 2.6970 0.0000 1.9890 0.7081 0.0019 1.4123 0.0627 3.4640

1980 16.2500 12.8765 1.3107 2.3175 0.0000 1.7090 0.6084 0.0007 1.3856 0.0418 3.1364

 

1981 16.0800 15.4804 1.6814 0.1163 0.0000 0.0857 0.0305 0.0018 0.0653 0.0904 0.2414

1982 22.7100 17.9448 4.2250 1.2675 0.0463 0.9006 0.3206 0.0628 0.7652 0.1771 1.8429

1983 19.1300 16.8197 1.2514 3.6330 0.0000 2.7134 0.9660 0.0024 1.7500 0.0686 4.5320

1984 20.3300 16.4206 2.4667 1.5311 0.0008 1.1285 0.4017 0.0667 1.0656 0.1158 2.3098

1985 18.8900 15.1276 3.0304 1.6750 0.0029 1.2337 0.4392 0.0132 1.4985 0.1407 2.8729

 

1986 14.7100 15.4574 1.9685 0.2288 0.0000 0.1708 0.0608 0.0000 0.0557 0.0686 0.2952

1987 20.4200 16.2487 2.3461 2.6676 0.0001 1.9672 0.7003 0.0064 1.1008 0.1314 3.1993

1988 17.9400 16.7736 1.9110 1.2456 0.0001 0.9186 0.3270 0.0017 0.3281 0.0924 1.3391

1989 13.3600 13.6023 1.5151 0.0998 0.0000 0.0736 0.0262 0.0000 0.0159 0.0613 0.1509

1990 20.2600 15.7920 3.3126 1.9115 0.0099 1.4024 0.4992 0.0333 0.6940 0.1048 2.2012

 

1991 19.0400 17.4488 2.0559 1.7503 0.0001 1.2980 0.4621 0.0094 1.0278 0.1634 2.4892

1992 18.6100 16.6524 2.3494 1.2602 0.0005 0.9290 0.3307 0.0135 0.3281 0.1223 1.3795

1993 13.9900 12.5810 2.5316 0.8588 0.0011 0.6329 0.2253 0.0005 0.3436 0.0628 1.0393

1994 17.4700 15.9041 2.0468 1.5503 0.0001 1.1440 0.4073 0.0009 0.4739 0.0858 1.7037

1995 21.0700 15.1366 2.1670 3.8462 0.0000 2.8365 1.0098 0.0037 1.9531 0.0991 4.8886

 

1996 13.5700 12.2335 3.3083 0.1157 0.0212 0.0697 0.0248 0.0013 0.0154 0.0605 0.1456

1997 17.2500 16.2648 3.0209 0.9201 0.0003 0.6940 0.2471 0.0142 0.2899 0.1180 1.1019

1998 18.7600 15.5102 1.9729 2.9631 0.0000 2.1853 0.7780 0.0086 1.3097 0.0887 3.5837

1999 16.5100 14.1776 1.9975 1.5367 0.0000 1.1333 0.4034 0.0014 0.7799 0.0764 1.9896

 

Period 873.870 771.474 1.997 65.641 0.000 48.409 17.233 0.001 32.650 4.954 86.013

Mean 17.1347 15.1270 2.1230 1.2871 0.0046 0.9492 0.3379 0.0144 0.6402 0.0971 1.6865

Median 16.6700 15.1796 1.9685 0.9339 0.0001 0.6940 0.2471 0.0019 0.4140 0.0924 1.3306

Stddev 2.9366 1.5827 0.8422 1.1225 0.0122 0.8297 0.2954 0.0407 0.6351 0.0360 1.4366

Minimum 10.8200 12.2027 0.7538 0.0343 0.0000 0.0236 0.0084 0.0000 0.0088 0.0278 0.1256

Maximum 24.8000 18.3137 4.2250 4.9651 0.0600 3.6595 1.3028 0.2710 3.0783 0.1849 6.7656
110 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

Table 31. Intrawatershed summary statistics for long-term simulations (October 1, 1948, through 

September 30, 1999) for areas of (A) metamorphic, (B) intrusive, and (C) fault-zone rocks and 

(D) Pikes Peak Granite in the Turkey Creek watershed—Continued

[Year, water year (October through September) if month not given; all numbers other than dates 

 in inches; Precip,total precipitation; ET, total evapotranspiration; sm, contents of soil-zone 

 reservoir at end of given period; bfi, total water added to base-flow reservoir; 

 bfr, contents of base-flow reservoir at end of accounting period; bf, total base flow 

 discharged to stream; gsnk, total water lost from base-flow reservoir that is not available to 

 support local streamflow; ir, contents of interflow reservoir at end of the accounting period; 

 if, total interflow; ovf, total overland flow; tf, total watershed flow; Period, October 1948 

 through September 1999; Stddev, standard deviation] 

----------------------------------------------------------------------------------------------------

Year Precip ET sm bfi bfr bf gsnk ir if ovf tf 

----------------------------------------------------------------------------------------------------

 B. Intrusive rocks

1949 17.8100 14.5179 1.0976 1.3005 0.0000 1.1725 0.1290 0.0000 0.8735 0.1506 2.1966

1950 15.4800 14.1891 1.8887 0.2570 0.0000 0.2316 0.0255 0.0000 0.1545 0.1159 0.5020

 

1951 16.1600 15.9392 1.5583 0.2627 0.0000 0.2366 0.0260 0.0000 0.2374 0.1196 0.5937

1952 16.4800 14.8826 1.1377 0.9825 0.0000 0.8851 0.0974 0.0000 0.9474 0.1360 1.9685

1953 15.8100 14.2554 1.1536 0.8235 0.0000 0.7419 0.0816 0.0000 0.6387 0.1229 1.5035

1954 14.3700 13.5489 1.8981 0.0401 0.0001 0.0360 0.0040 0.0007 0.0091 0.0898 0.1349

1955 18.9600 16.4200 2.6617 0.7498 0.0000 0.6756 0.0743 0.0008 0.9272 0.1581 1.7609

 

1956 10.8200 12.4155 0.7732 0.2355 0.0000 0.2121 0.0233 0.0000 0.0239 0.0504 0.2865

1957 20.3200 14.7876 1.7631 3.2314 0.0000 2.9112 0.3202 0.0000 1.2878 0.0733 4.2723

1958 16.2100 13.2570 1.7780 2.2206 0.0000 2.0005 0.2201 0.0000 0.6934 0.0677 2.7617

1959 15.5600 12.6575 1.5479 0.8256 0.0000 0.7438 0.0818 0.0000 0.1438 0.0342 0.9218

1960 13.8100 12.4332 1.2631 2.4331 0.0000 2.1920 0.2411 0.0000 1.3790 0.0535 3.6245

 

1961 21.8700 16.7808 4.0408 1.1276 0.0084 1.0083 0.1109 0.1507 0.8864 0.1826 2.0773

1962 12.3100 12.8526 0.8936 2.2981 0.0000 2.0779 0.2286 0.0000 0.4223 0.0788 2.5790

1963 16.5600 12.4599 3.4989 0.9456 0.0000 0.8519 0.0937 0.0091 0.4757 0.1157 1.4433

1964 12.8700 13.7757 1.2360 0.9634 0.0000 0.8680 0.0955 0.0000 0.3784 0.0578 1.3042

1965 19.2600 14.2828 3.8750 1.0652 0.0097 0.9509 0.1046 0.0088 1.0887 0.1025 2.1421

 

1966 14.8200 16.3247 1.8145 0.5846 0.0000 0.5354 0.0589 0.0000 0.0765 0.0717 0.6836

1967 17.3500 15.6211 2.2874 0.7928 0.0000 0.7142 0.0786 0.0000 0.4174 0.1031 1.2347

1968 14.6400 14.1273 1.9173 0.7529 0.0000 0.6783 0.0746 0.0000 0.0863 0.0640 0.8286

1969 21.4100 17.3113 2.2187 2.8167 0.0000 2.5375 0.2791 0.0008 0.9171 0.1104 3.5650

1970 24.8000 16.7605 2.9754 3.9023 0.0050 3.5112 0.3862 0.0024 2.8137 0.0924 6.4172

 

1971 17.7900 14.9448 3.1236 1.6287 0.0067 1.4657 0.1612 0.0076 1.1040 0.0894 2.6591

1972 15.2500 15.2338 2.1533 0.8984 0.0000 0.8154 0.0897 0.0002 0.4829 0.0660 1.3644

1973 21.1600 13.5623 1.9830 5.0580 0.0024 4.5545 0.5010 0.0000 2.6161 0.0226 7.1933

1974 16.2200 14.7678 1.5616 1.6298 0.0000 1.4705 0.1617 0.0000 0.3028 0.0549 1.8282

1975 14.9700 13.4527 1.4070 0.9074 0.0000 0.8175 0.0899 0.0000 0.6601 0.1263 1.6039

 

1976 17.4600 13.9674 2.7021 1.5727 0.0019 1.4151 0.1557 0.0034 0.5261 0.0770 2.0182

1977 16.6700 15.5979 1.7377 1.6190 0.0000 1.4602 0.1606 0.0001 0.4107 0.0904 1.9614

1978 12.0300 11.8787 1.2080 0.4837 0.0000 0.4358 0.0479 0.0000 0.1725 0.0499 0.6582

1979 18.2900 13.3174 1.6100 3.0195 0.0000 2.7202 0.2992 0.0000 1.5309 0.0469 4.2981

1980 16.2500 12.6755 1.3013 2.5957 0.0000 2.3385 0.2572 0.0000 1.2844 0.0354 3.6582

 

1981 16.0800 15.1805 1.7151 0.2873 0.0000 0.2588 0.0285 0.0000 0.1689 0.0860 0.5137

1982 22.7100 17.1809 4.0496 1.8672 0.0047 1.6779 0.1846 0.0118 1.1624 0.1690 3.0093

1983 19.1300 16.1222 1.2364 3.8067 0.0000 3.4336 0.3777 0.0000 2.0423 0.0583 5.5343

1984 20.3300 15.8134 2.3924 1.7825 0.0000 1.6059 0.1766 0.0014 1.5104 0.1116 3.2279

1985 18.8900 14.1325 2.9524 2.2598 0.0012 2.0348 0.2238 0.0098 1.7980 0.1253 3.9581

 

1986 14.7100 15.1628 1.9355 0.4646 0.0000 0.4196 0.0462 0.0000 0.0855 0.0637 0.5688

1987 20.4200 15.0572 2.3781 3.4390 0.0000 3.0982 0.3408 0.0003 1.4283 0.1212 4.6478

1988 17.9400 15.9285 1.9128 1.9437 0.0000 1.7511 0.1926 0.0000 0.5024 0.0838 2.3372

1989 13.3600 13.4865 1.5047 0.2068 0.0000 0.1863 0.0205 0.0000 0.0362 0.0569 0.2794

1990 20.2600 15.0381 3.2856 2.5477 0.0043 2.2913 0.2521 0.0460 0.7913 0.0905 3.1731

 

1991 19.0400 16.3651 2.0463 2.5506 0.0000 2.3017 0.2532 0.0000 1.2877 0.1526 3.7420

1992 18.6100 15.6344 2.3887 2.0075 0.0000 1.8086 0.1989 0.0004 0.5510 0.1096 2.4692

1993 13.9900 11.9224 2.5956 1.2900 0.0001 1.1621 0.1278 0.0000 0.5216 0.0516 1.7354

1994 17.4700 14.9114 2.0621 2.3256 0.0000 2.0952 0.2305 0.0000 0.7351 0.0752 2.9055

1995 21.0700 14.0586 2.1547 4.5998 0.0000 4.1440 0.4558 0.0000 2.2670 0.0838 6.4948

 

1996 13.5700 12.1782 3.2210 0.2407 0.0146 0.2037 0.0224 0.0005 0.0105 0.0548 0.2690

1997 17.2500 15.2894 3.0396 1.5660 0.0000 1.4240 0.1566 0.0003 0.5383 0.1108 2.0731

1998 18.7600 14.9901 1.9625 3.3273 0.0000 2.9976 0.3297 0.0000 1.4377 0.0822 4.5175

1999 16.5100 13.6495 1.9939 2.1231 0.0000 1.9127 0.2104 0.0000 0.6899 0.0700 2.6726

 

Period 873.870 741.101 1.994 86.660 0.000 78.073 8.588 0.000 41.533 4.567 124.173

 

Mean 17.1347 14.5314 2.0959 1.6992 0.0012 1.5308 0.1684 0.0050 0.8144 0.0895 2.4348

Median 16.6700 14.7678 1.9355 1.5727 0.0000 1.4240 0.1566 0.0000 0.6601 0.0838 2.0773

Stddev 2.9366 1.4270 0.8053 1.2023 0.0029 1.0833 0.1192 0.0219 0.6744 0.0364 1.6984

Minimum 10.8200 11.8787 0.7732 0.0401 0.0000 0.0360 0.0040 0.0000 0.0091 0.0226 0.1349

Maximum 24.8000 17.3113 4.0496 5.0580 0.0146 4.5545 0.5010 0.1507 2.8137 0.1826 7.1933
ASSESSMENT OF WATER RESOURCES 111

Table 31. Intrawatershed summary statistics for long-term simulations (October 1, 1948, through 

September 30, 1999) for areas of (A) metamorphic, (B) intrusive, and (C) fault-zone rocks and 

(D) Pikes Peak Granite in the Turkey Creek watershed—Continued

[Year, water year (October through September) if month not given; all numbers other than dates 

 in inches; Precip,total precipitation; ET, total evapotranspiration; sm, contents of soil-zone 

 reservoir at end of given period; bfi, total water added to base-flow reservoir; 

 bfr, contents of base-flow reservoir at end of accounting period; bf, total base flow 

 discharged to stream; gsnk, total water lost from base-flow reservoir that is not available to 

 support local streamflow; ir, contents of interflow reservoir at end of the accounting period; 

 if, total interflow; ovf, total overland flow; tf, total watershed flow; Period, October 1948 

 through September 1999; Stddev, standard deviation] 

----------------------------------------------------------------------------------------------------

Year Precip ET sm bfi bfr bf gsnk ir if ovf tf 

----------------------------------------------------------------------------------------------------

 C. Fault-zone rocks

1949 17.8100 14.2119 0.9796 0.7812 1.2457 0.2060 0.3295 0.0000 1.8223 0.1479 2.1762

1950 15.4800 14.1136 1.7705 0.1887 0.9016 0.2050 0.3278 0.0000 0.3056 0.1156 0.6261

 

1951 16.1600 15.8547 1.4268 0.2158 0.7136 0.1554 0.2484 0.0000 0.3972 0.1192 0.6717

1952 16.4800 14.6906 1.0411 0.5551 0.8750 0.1515 0.2422 0.0000 1.5507 0.1338 1.8360

1953 15.8100 13.9955 1.0214 0.5456 0.9683 0.1740 0.2783 0.0000 1.2157 0.1221 1.5118

1954 14.3700 13.5398 1.8281 0.0000 0.5745 0.1515 0.2423 0.0000 0.0000 0.0908 0.2424

1955 18.9600 16.2463 2.4603 0.4003 0.6907 0.1093 0.1748 0.0001 1.5889 0.1565 1.8547

 

1956 10.8200 12.3695 0.6973 0.1257 0.5123 0.1170 0.1871 0.0000 0.0650 0.0497 0.2317

1957 20.3200 14.5197 1.6523 1.4902 1.5440 0.1764 0.2821 0.0000 3.3287 0.0744 3.5795

1958 16.2100 13.1184 1.7033 1.0361 1.7597 0.3157 0.5048 0.0000 1.9870 0.0655 2.3682

1959 15.5600 12.4339 1.4511 0.5751 1.5154 0.3152 0.5041 0.0000 0.6428 0.0367 0.9948

1960 13.8100 12.3768 1.1906 1.3483 1.9538 0.3501 0.5598 0.0000 2.4981 0.0529 2.9011

 

1961 21.8700 16.7608 3.6351 0.7999 1.8338 0.3539 0.5660 0.1772 1.5691 0.1813 2.1044

1962 12.3100 12.4980 0.8105 1.3304 2.0690 0.4214 0.6739 0.0000 1.4497 0.0743 1.9454

1963 16.5600 12.4791 3.1145 0.5877 1.7899 0.3335 0.5333 0.0306 1.0921 0.1149 1.5405

1964 12.8700 13.3589 1.1490 0.5231 1.4907 0.3164 0.5059 0.0000 0.9688 0.0511 1.3362

1965 19.2600 13.9920 3.6017 0.6809 1.4861 0.2637 0.4217 0.0310 1.8587 0.1049 2.2273

 

1966 14.8200 16.0932 1.7012 0.3760 1.1770 0.2636 0.4215 0.0000 0.4440 0.0708 0.7784

1967 17.3500 15.3501 2.1191 0.5631 1.1869 0.2129 0.3404 0.0001 0.9656 0.1014 1.2798

1968 14.6400 13.8785 1.8079 0.4449 1.0682 0.2168 0.3467 0.0000 0.5916 0.0658 0.8741

1969 21.4100 16.8867 2.0537 1.6238 1.9480 0.2863 0.4578 0.0010 2.5857 0.1065 2.9785

1970 24.8000 16.6239 2.6261 1.7812 2.6317 0.4223 0.6753 0.0000 4.9984 0.0927 5.5134

 

1971 17.7900 14.5670 2.8085 1.1191 2.4633 0.4953 0.7921 0.0000 2.0196 0.0865 2.6014

1972 15.2500 14.9471 2.0228 0.6333 1.9704 0.4333 0.6929 0.0006 1.0385 0.0688 1.5406

1973 21.1600 12.9007 1.7547 2.2076 3.0243 0.4439 0.7099 0.0000 6.1387 0.0259 6.6085

1974 16.2200 14.5124 1.4408 0.9090 2.5324 0.5389 0.8618 0.0000 1.2772 0.0528 1.8690

1975 14.9700 13.1270 1.2850 0.6193 1.9794 0.4510 0.7213 0.0000 1.3011 0.1251 1.8772

 

1976 17.4600 13.5426 2.4699 0.8696 1.9006 0.3649 0.5835 0.0000 1.6894 0.0739 2.1282

1977 16.6700 15.2084 1.5182 1.0373 1.9699 0.3724 0.5956 0.0003 1.4672 0.0880 1.9277

1978 12.0300 11.7230 1.1046 0.2412 1.3639 0.3260 0.5213 0.0000 0.4618 0.0500 0.8377

1979 18.2900 13.3185 1.5183 1.3402 1.9363 0.2954 0.4724 0.0000 3.1925 0.0519 3.5399

1980 16.2500 12.7057 1.2261 1.2451 2.1782 0.3860 0.6172 0.0000 2.5877 0.0366 3.0102

 

1981 16.0800 15.0974 1.5676 0.2016 1.4713 0.3495 0.5590 0.0001 0.4022 0.0867 0.8384

1982 22.7100 17.0334 3.6985 1.0166 1.7928 0.2674 0.4277 0.0380 2.3465 0.1607 2.7747

1983 19.1300 15.9464 1.1335 1.4976 2.3197 0.3735 0.5972 0.0000 4.3036 0.0602 4.7373

1984 20.3300 15.5926 2.1739 0.9463 2.1940 0.4125 0.6596 0.0015 2.6812 0.1080 3.2017

1985 18.8900 13.8049 2.8717 1.2115 2.2596 0.4409 0.7050 0.0000 3.0685 0.1263 3.6358

 

1986 14.7100 15.0373 1.8328 0.4023 1.6524 0.3884 0.6211 0.0000 0.2743 0.0648 0.7276

1987 20.4200 15.1340 2.1899 1.6340 2.2960 0.3810 0.6093 0.0007 3.2513 0.1137 3.7460

1988 17.9400 15.6703 1.7623 0.9538 2.1214 0.4341 0.6942 0.0001 1.7099 0.0831 2.2271

1989 13.3600 13.4470 1.3976 0.1233 1.3597 0.3405 0.5445 0.0000 0.1200 0.0572 0.5177

1990 20.2600 15.0645 3.1069 1.3461 1.9158 0.3039 0.4860 0.0766 1.9997 0.0921 2.3957

 

1991 19.0400 16.0027 1.8112 1.4655 2.3135 0.4109 0.6570 0.0001 2.8358 0.1448 3.3914

1992 18.6100 15.4546 2.0914 1.1309 2.3289 0.4292 0.6863 0.0008 1.6804 0.1062 2.2158

1993 13.9900 11.6136 2.4754 0.6540 1.9186 0.4095 0.6548 0.0000 1.2511 0.0512 1.7118

1994 17.4700 14.5893 1.9410 1.2608 2.1578 0.3931 0.6285 0.0002 2.1705 0.0733 2.6368

1995 21.0700 13.9805 2.0347 2.0535 3.0266 0.4558 0.7289 0.0000 4.8819 0.0843 5.4220

 

1996 13.5700 12.1976 3.0712 0.1491 1.9363 0.4769 0.7626 0.0181 0.0557 0.0559 0.5884

1997 17.2500 15.0242 2.6798 1.0415 2.0227 0.3675 0.5876 0.0006 1.6018 0.1058 2.0751

1998 18.7600 14.7058 1.7816 1.5726 2.5420 0.4053 0.6481 0.0000 3.3031 0.0794 3.7878

1999 16.5100 13.5014 1.8251 1.0387 2.3892 0.4584 0.7331 0.0000 1.8978 0.0685 2.4247

 

Period 873.870 730.842 1.825 45.894 2.389 17.123 27.382 0.000 92.934 4.511 114.569

 

Mean 17.1347 14.3302 1.9301 0.8999 1.7897 0.3358 0.5369 0.0074 1.8222 0.0884 2.2464

Median 16.6700 14.5124 1.8079 0.9090 1.9186 0.3539 0.5660 0.0000 1.6018 0.0843 2.1044

Stddev 2.9366 1.4108 0.7378 0.5314 0.6014 0.1066 0.1705 0.0276 1.3440 0.0350 1.3830

Minimum 10.8200 11.6136 0.6973 0.0000 0.5123 0.1093 0.1748 0.0000 0.0000 0.0259 0.2317

Maximum 24.8000 17.0334 3.6985 2.2076 3.0266 0.5389 0.8618 0.1772 6.1387 0.1813 6.6085
112 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

Table 31. Intrawatershed summary statistics for long-term simulations (October 1, 1948, through 

September 30, 1999) for areas of (A) metamorphic, (B) intrusive, and (C) fault-zone rocks and 

(D) Peak Granite in the Turkey Creek watershed—Continued 

[Year, water year (October through September) if month not given; all numbers other than dates 

 in inches; Precip,total precipitation; ET, total evapotranspiration; sm, contents of soil-zone 

 reservoir at end of given period; bfi, total water added to base-flow reservoir; 

 bfr, contents of base-flow reservoir at end of accounting period; bf, total base flow 

 discharged to stream; gsnk, total water lost from base-flow reservoir that is not available to 

 support local streamflow; ir, contents of interflow reservoir at end of the accounting period; 

 if, total interflow; ovf, total overland flow; tf, total watershed flow; Period, October 1948 

 through September 1999; Stddev, standard deviation] 

----------------------------------------------------------------------------------------------------

Year Precip ET sm bfi bfr bf gsnk ir if ovf tf 

----------------------------------------------------------------------------------------------------

 D. Pikes Peak Granite

1949 17.8100 12.3198 0.3431 3.6981 3.5213 0.5356 2.1412 0.0000 1.4564 0.1164 2.1084

1950 15.4800 13.0956 1.1677 1.1512 2.1388 0.5070 2.0267 0.0000 0.3400 0.0961 0.9431

 

1951 16.1600 14.6335 0.8169 1.2106 1.6506 0.3399 1.3589 0.0001 0.6105 0.0989 1.0493

1952 16.4800 12.8457 0.6422 2.5089 2.2553 0.3810 1.5231 0.0000 1.2307 0.1071 1.7188

1953 15.8100 12.2156 0.4545 2.5889 2.6197 0.4451 1.7794 0.0000 1.1004 0.0992 1.6447

1954 14.3700 13.3262 1.4806 0.0000 0.9592 0.3322 1.3283 0.0000 0.0000 0.0782 0.4104

1955 18.9600 14.3379 1.6108 2.5021 2.2485 0.2427 0.9702 0.0001 1.8997 0.1284 2.2708

 

1956 10.8200 11.5258 0.2975 0.5073 1.1730 0.3167 1.2660 0.0000 0.0509 0.0388 0.4064

1957 20.3200 13.3507 0.9377 4.5456 3.7475 0.3944 1.5767 0.0000 1.7779 0.0394 2.2117

1958 16.2100 11.5906 1.1491 3.3694 3.6990 0.6839 2.7340 0.0000 1.0355 0.0373 1.7567

1959 15.5600 11.4893 0.7430 1.9326 2.6894 0.5887 2.3535 0.0000 0.1088 0.0236 0.7211

1960 13.8100 11.5386 0.8557 3.5426 3.3935 0.5680 2.2705 0.0000 1.0353 0.0186 1.6218

 

1961 21.8700 15.1105 2.2384 3.7454 3.9066 0.6468 2.5856 0.2111 1.3046 0.1450 2.0964

1962 12.3100 10.6733 0.4260 3.2547 3.2469 0.7832 3.1312 0.0000 0.3744 0.0494 1.2070

1963 16.5600 12.0362 1.7756 2.3556 3.3295 0.4548 1.8182 0.0128 0.7392 0.0916 1.2856

1964 12.8700 11.6791 0.6879 1.7725 2.4664 0.5273 2.1082 0.0000 0.5005 0.0324 1.0602

1965 19.2600 12.0502 1.8300 3.3901 3.5227 0.4670 1.8668 0.0001 1.5898 0.0679 2.1247

 

1966 14.8200 14.8384 1.0824 1.5626 2.3461 0.5481 2.1911 0.0000 0.1906 0.0537 0.7923

1967 17.3500 13.7432 1.1904 2.5378 2.7868 0.4196 1.6775 0.0001 0.9039 0.0690 1.3926

1968 14.6400 13.3956 1.2180 1.0066 1.7360 0.4117 1.6458 0.0000 0.1776 0.0484 0.6376

1969 21.4100 14.4661 1.0210 5.8165 4.7448 0.5618 2.2460 0.0023 1.2627 0.0710 1.8955

1970 24.8000 14.4480 1.1736 6.1520 6.2976 0.9202 3.6789 0.0001 2.4764 0.0558 3.4525

 

1971 17.7900 12.5858 1.5878 4.0570 5.1994 1.0315 4.1238 0.0000 1.1274 0.0563 2.2152

1972 15.2500 13.6045 1.4396 2.3826 3.6036 0.7960 3.1823 0.0005 0.4490 0.0503 1.2954

1973 21.1600 12.0268 0.9573 6.8732 6.4788 0.7999 3.1980 0.0000 2.1881 0.0156 3.0036

1974 16.2200 13.8892 0.8999 2.5945 4.1920 0.9767 3.9047 0.0000 0.3136 0.0365 1.3268

1975 14.9700 11.3278 0.7174 2.8748 3.2757 0.7585 3.0325 0.0000 0.8708 0.0997 1.7291

 

1976 17.4600 11.4443 1.5814 3.4065 3.7127 0.5942 2.3754 0.0000 1.2982 0.0443 1.9366

1977 16.6700 13.5631 0.7884 3.6711 3.8759 0.7019 2.8060 0.0004 0.5893 0.0631 1.3543

1978 12.0300 10.4838 0.6850 1.3188 2.3059 0.5780 2.3108 0.0000 0.2988 0.0375 0.9144

1979 18.2900 12.5607 0.8613 4.4687 4.1499 0.5252 2.0995 0.0000 1.0301 0.0348 1.5900

1980 16.2500 12.4892 0.7299 3.0051 3.6900 0.6933 2.7717 0.0000 0.8723 0.0249 1.5905

 

1981 16.0800 13.9902 0.8906 1.3901 2.4395 0.5284 2.1123 0.0001 0.4849 0.0701 1.0834

1982 22.7100 14.9314 2.2298 4.6885 4.6758 0.4906 1.9615 0.0205 1.6116 0.1078 2.2101

1983 19.1300 13.8735 0.5357 4.8672 5.3165 0.8457 3.3808 0.0000 2.1365 0.0370 3.0192

1984 20.3300 13.9549 1.0328 4.0047 5.0646 0.8517 3.4050 0.0019 1.8071 0.0788 2.7376

1985 18.8900 11.4471 1.7548 4.5840 5.0022 0.9297 3.7168 0.0001 1.7179 0.0636 2.7112

 

1986 14.7100 14.1022 1.1374 1.2896 2.7236 0.7139 2.8542 0.0000 0.2219 0.0455 0.9813

1987 20.4200 12.8037 1.3983 5.4895 4.7561 0.6917 2.7654 0.0015 1.8459 0.0651 2.6027

1988 17.9400 13.9668 1.1851 3.3745 4.0874 0.8090 3.2341 0.0001 0.7617 0.0539 1.6246

1989 13.3600 12.8940 0.8737 0.6445 1.9368 0.5593 2.2358 0.0000 0.0986 0.0408 0.6987

1990 20.2600 14.1280 2.2149 3.7519 3.5030 0.4373 1.7484 0.1499 0.8319 0.0613 1.3306

 

1991 19.0400 13.4639 0.8139 5.5535 5.0469 0.8023 3.2073 0.0001 1.4969 0.0890 2.3883

1992 18.6100 13.8217 1.1428 3.6953 4.5986 0.8291 3.3145 0.0000 0.7011 0.0663 1.5965

1993 13.9900 10.4892 1.8921 2.2357 3.2603 0.7151 2.8589 0.0000 0.3049 0.0287 1.0487

1994 17.4700 13.0953 1.4588 4.1105 3.9856 0.6773 2.7079 0.0000 0.8625 0.0463 1.5862

1995 21.0700 11.9872 1.2489 6.7455 6.6464 0.8173 3.2675 0.0000 2.5026 0.0240 3.3440

 

1996 13.5700 11.9277 2.2103 0.5052 2.9101 0.8486 3.3927 0.0017 0.0066 0.0397 0.8950

1997 17.2500 12.9789 1.4888 3.9239 3.9957 0.5679 2.2704 0.0007 1.1676 0.0750 1.8106

1998 18.7600 13.1047 0.9115 4.7424 5.1028 0.7274 2.9080 0.0000 1.4318 0.0550 2.2141

1999 16.5100 11.7437 1.1903 3.9409 4.7993 0.8493 3.3952 0.0000 0.5303 0.0402 1.4198

 

Period 873.870 657.390 1.190 163.341 4.799 32.222 128.819 0.000 49.726 3.117 85.066

Mean 17.1347 12.8900 1.1569 3.2028 3.6238 0.6318 2.5259 0.0079 50.9750 70.0611 1.6680

Median 16.6700 12.9789 1.1374 3.3745 3.6036 0.5942 2.3754 0.0000 0.8723 0.0550 1.5965

Stddev 2.9366 1.2113 0.4967 1.6469 1.3052 0.1890 0.7556 0.0359 0.6708 0.0296 0.7347

Minimum 10.8200 10.4838 0.2975 0.0000 0.9592 0.2427 0.9702 0.0000 0.0000 0.0156 0.4064

Maximum 24.8000 15.1105 2.2384 6.8732 6.6464 1.0315 4.1238 0.2111 2.5026 0.1450 3.4525

-----------------------------------------------------------------------------------------------------
ASSESSMENT OF WATER RESOURCES 113

The contemporary (2001) estimate for the 

number of occupied households in the watershed is 

about 4,900, and the SEO estimates, for permitting 

purposes, that household use is 300 gallons per day, 

or about 1,650 acre-feet for the entire watershed on 

an annual basis. Records from local residential supply 

systems (Diana Hunter, Indian Hills Water District, 

written commun., 2001; Norman Lewis, Homestead 

Water District, written commun., 2001; and Roger 

Migchelbrink, Will-O-Wisp Water District, oral 

commun., 2001), which represent the use for about 

600 households, indicate that water use, at least for 

these 600 or so households, is about 200 gallons per day 

or about 67 percent of the commonly cited 300 gallons 

per day amount. On the basis of this information this 

report will bracket estimates of daily water withdrawals 

as about 200 to 300 gallons per day per household. This 

amount of water, referred to as “estimated withdrawals” 

in this report, corresponds to a watershed depth of 0.43 

to 0.65 inch per year, or 0.0012 to 0.0018 inch per day. 

These values are small; however, the values of many 

terms in the water balance summaries in tables 28–32, 

such as input to and contents of the base-flow reservoirs, also are small. 

Table 32. Summary statistics of daily values for water-balance terms from long-term simulations for 

(A) the entire Turkey Creek watershed and for areas of (B) metamorphic, (C) intrusive, and (D) fault-zone 

rocks and (E) Pikes Peak Granite

[All univariate statistics and percentiles reported in inches; Precip, total precipitation;

ET, total evapotranspiration; sm, contents of soil-zone reservoir at end of given period;

 bfi, total water added to base-flow reservoir; bfr, contents of base-flow reservoir at end

 of accounting period; bf, total base flow discharged to stream; gsnk, total water lost from

 base-flow reservoir that is not available to support local streamflow; ir, contents of 

 interflow reservoir at end of the accounting period; if, total interflow; ovf, total overland 

 flow; tf, total watershed flow; Min, minimum; Max, maximum, Stddev, standard deviation; N,

 number of observations; %, percentage]

 A. Entire Turkey Creek Watershed

 

 Univariate statistics

-------------------------------------------------------------------- 

 

Variable Mean Median Stddev Min Max N 

-------- ------ ------ ------ ------ ------ ---- 

Precip 0.0469 0.0000 0.1461 0.0000 2.6500 18627

ET 0.0406 0.0258 0.0415 0.0000 0.2249 18627

sm 2.3514 2.2973 0.8457 0.1374 4.1913 18627

bfi 0.0038 0.0000 0.0165 0.0000 0.1812 18627

bfr 0.1983 0.1944 0.0844 0.0423 0.7757 18627

bf 0.0029 0.0002 0.0091 0.0000 0.1029 18627

gsnk 0.0010 0.0003 0.0023 0.0001 0.0266 18627

ir 0.0255 0.0015 0.0736 0.0000 0.9793 18627

if 0.0021 0.0001 0.0068 0.0000 0.1067 18627

ovf 0.0003 0.0000 0.0011 0.0000 0.0268 18627

tf 0.0053 0.0005 0.0154 0.0000 0.1899 18627

 

 Percentiles

----------------------------------------------------------------------------------------------

Variable 0.1% 1.0% 5.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 

-------- ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ 

bfr 0.0439 0.0519 0.0742 0.0957 0.1261 0.1549 0.1743 0.1944 0.2122 0.2315 0.2562 0.2929

ir 0.0000 0.0000 0.0000 0.0000 0.0000 0.0002 0.0005 0.0015 0.0037 0.0084 0.0225 0.0644

 

 Correlations 

----------------------------------------------------------------------------------------------------------

Variable Precip ET sm bfi bfr bf gsnk ir if ovf tf

-------- ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ 

Precip 1.0000 0.0189 0.1313 0.2827 0.0705 0.1427 0.1152 0.1311 0.0918 0.7796 0.1788

ET 0.0189 1.0000 0.2145 0.1381 0.2996 0.2429 0.2618 0.3618 0.3444 0.1081 0.3037

sm 0.1313 0.2145 1.0000 0.3805 0.4162 0.4814 0.4922 0.4388 0.4234 0.1550 0.4827

bfi 0.2827 0.1381 0.3805 1.0000 0.4478 0.8532 0.8051 0.6232 0.5765 0.3590 0.7841

bfr 0.0705 0.2996 0.4162 0.4478 1.0000 0.5968 0.6359 0.6051 0.5873 0.1021 0.6199

bf 0.1427 0.2429 0.4814 0.8532 0.5968 1.0000 0.9920 0.8257 0.8140 0.1845 0.9641

gsnk 0.1152 0.2618 0.4922 0.8051 0.6359 0.9920 1.0000 0.8498 0.8394 0.1440 0.9679

ir 0.1311 0.3618 0.4388 0.6232 0.6051 0.8257 0.8498 1.0000 0.9877 0.1875 0.9387

if 0.0918 0.3444 0.4234 0.5765 0.5873 0.8140 0.8394 0.9877 1.0000 0.1379 0.9339

ovf 0.7796 0.1081 0.1550 0.3590 0.1021 0.1845 0.1440 0.1875 0.1379 1.0000 0.2392

tf 0.1788 0.3037 0.4827 0.7841 0.6199 0.9641 0.9679 0.9387 0.9339 0.2392 1.0000
114 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

Various water-balance terms can be compared to 

estimated withdrawals to evaluate their relative magnitudes and also the effects of the withdrawals on the 

watershed system. Comparisons to recharge are considered unrealistic principally because much recharge 

leaves the watershed as streamflow. If interflow is 

discounted, due to its intermittent nature as described in 

the “Runoff Modeling” section, then water associated 

with base flow becomes the next term of interest. The 

PRMS watershed characterization provides quantitative 

estimates of all terms related to base flow as described in 

equation 3 from the “Watershed Characterization Using 

the Precipitation-Runoff Modeling System” section; 

equation 3 is essentially a water balance for the baseflow reservoir. A term that is not described by equation 3 

is the total amount of ground water in the system (the 

product of aquifer volume and porosity). Although estimates of porosity are presented in this report, the total

Table 32. Summary statistics of daily values for water-balance terms from long-term simulations for 

(A) the entire Turkey Creek watershed and areas of (B) metamorphic, (C) intrusive, and (D) fault-zone 

rocks and (E) Pikes Peak Granite—Continued

[All univariate statistics and percentiles reported in inches; Precip, total precipitation;

ET, total evapotranspiration; sm, contents of soil-zone reservoir at end of given period;

 bfi, total water added to base-flow reservoir; bfr, contents of base-flow reservoir at end

 of accounting period; bf, total base flow discharged to stream; gsnk, total water lost from

 base-flow reservoir that is not available to support local streamflow; ir, contents of 

 interflow reservoir at end of the accounting period; if, total interflow; ovf, total overland 

 flow; tf, total watershed flow; Min, minimum; Max, maximum, Stddev, standard deviation; N,

 number of observations; %, percentage]

 B. Metamorphic Rocks 

 

 Univariate statistics 

-------------------------------------------------------------------- 

 

Variable Mean Median Stddev Min Max N 

-------- ------ ------ ------ ------ ------ ---- 

Precip 0.0469 0.0000 0.1461 0.0000 2.6500 18627

ET 0.0414 0.0266 0.0419 0.0000 0.2283 18627

sm 2.3960 2.3270 0.8708 0.1380 4.3536 18627

bfi 0.0035 0.0000 0.0165 0.0000 0.1905 18627

bfr 0.0201 0.0007 0.0639 0.0000 0.7313 18627

bff 0.0026 0.0001 0.0083 0.0000 0.0945 18627

gsnk 0.0009 0.0000 0.0029 0.0000 0.0337 18627

ir 0.0297 0.0021 0.0838 0.0000 1.1221 18627

if 0.0018 0.0001 0.0056 0.0000 0.0907 18627

ovf 0.0003 0.0000 0.0011 0.0000 0.0271 18627

tf 0.0062 0.0012 0.0160 0.0002 0.2242 18627

 Percentiles

----------------------------------------------------------------------------------------------

Variable 0.1% 1.0% 5.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 

-------- ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ 

 

bfr 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0002 0.0007 0.0019 0.0047 0.0131 0.0474

ir 0.0000 0.0000 0.0000 0.0000 0.0000 0.0002 0.0008 0.0021 0.0049 0.0108 0.0271 0.0780

 

 Correlations 

----------------------------------------------------------------------------------------------------------

Variable Precip ET sm bfi bfr bf gsnk ir if ovf tf

-------- ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ 

Precip 1.0000 0.0223 0.1343 0.2713 0.0923 0.0923 0.0923 0.1066 0.0659 0.7867 0.1477

ET 0.0223 1.0000 0.2243 0.1107 0.2639 0.2639 0.2639 0.3646 0.3371 0.1101 0.3108

sm 0.1343 0.2243 1.0000 0.3676 0.4968 0.4968 0.4968 0.4321 0.3970 0.1594 0.4827

bfi 0.2713 0.1107 0.3676 1.0000 0.7385 0.7385 0.7385 0.5711 0.5222 0.3384 0.6976

bfr 0.0923 0.2639 0.4968 0.7385 1.0000 1.0000 1.0000 0.8476 0.8367 0.1174 0.9706

bff 0.0923 0.2639 0.4968 0.7385 1.0000 1.0000 1.0000 0.8476 0.8367 0.1174 0.9706

gsnk 0.0923 0.2639 0.4968 0.7385 1.0000 1.0000 1.0000 0.8476 0.8367 0.1174 0.9706

ir 0.1066 0.3646 0.4321 0.5711 0.8476 0.8476 0.8476 1.0000 0.9881 0.1542 0.9427

if 0.0659 0.3371 0.3970 0.5222 0.8367 0.8367 0.8367 0.9881 1.0000 0.0983 0.9363

ovf 0.7867 0.1101 0.1594 0.3384 0.1174 0.1174 0.1174 0.1542 0.0983 1.0000 0.1939

tf 0.1477 0.3108 0.4827 0.6976 0.9706 0.9706 0.9706 0.9427 0.9363 0.1939 1.0000
ASSESSMENT OF WATER RESOURCES 115

amount of ground water in the system remains unknown 

because the dimensions of the system, or aquifer 

volume, are unknown. The map surface dimensions, or 

x and y, are presumed to be the watershed; however, the 

depth dimension, or z, is not known. 

An evaluation of equation 3 using results listed 

in table 27, table 28, table 30, or table 31 indicates that 

the BFR is often negative, which indicates that the 

contents of the base-flow reservoir are being depleted. 

Should the contents of the base-flow reservoir be 

completely depleted, not only will there be no base 

flow, but GSNK, which comes from the base-flow 

reservoirs, also will be zero. If the contents of baseflow reservoirs are zero, ground water can still leave 

the watershed by evapotranspiration, in areas where 

the water table is shallow, by underflow, by withdrawals made for domestic use, or in various combinations of all three. Under these conditions, streamflow 

will not resume until the contents of base-flow reservoirs becomes greater than zero. 

∆

Table 32. Summary statistics of daily values for water-balance terms from long-term simulations for 

(A) the entire Turkey Creek watershed and areas of (B) metamorphic, (C) intrusive, and (D) fault-zone 

rocks and (E) Pikes Peak Granite—Continued

[All univariate statistics and percentiles reported in inches; Precip, total precipitation;

ET, total evapotranspiration; sm, contents of soil-zone reservoir at end of given period;

 bfi, total water added to base-flow reservoir; bfr, contents of base-flow reservoir at end

 of accounting period; bf, total base flow discharged to stream; gsnk, total water lost from

 base-flow reservoir that is not available to support local streamflow; ir, contents of 

 interflow reservoir at end of the accounting period; if, total interflow; ovf, total overland 

 flow; tf, total watershed flow; Min, minimum; Max, maximum, Stddev, standard deviation; N,

 number of observations; %, percentage]

 C. Intrusive rocks

 Univariate statistics 

-------------------------------------------------------------------- 

 

Variable Mean Median Stddev Min Max N 

-------- ------ ------ ------ ------ ------ ---- 

Precip 0.0469 0.0000 0.1461 0.0000 2.6500 18627

ET 0.0398 0.0247 0.0415 0.0000 0.2197 18627

sm 2.3793 2.3411 0.8418 0.1346 4.0987 18627

bfi 0.0047 0.0000 0.0198 0.0000 0.1904 18627

bfr 0.0037 0.0000 0.0137 0.0000 0.1424 18627

bf 0.0042 0.0000 0.0154 0.0000 0.1600 18627

gsnk 0.0005 0.0000 0.0017 0.0000 0.0176 18627

ir 0.0140 0.0000 0.0517 0.0000 1.0063 18627

if 0.0022 0.0000 0.0082 0.0000 0.1603 18627

ovf 0.0002 0.0000 0.0011 0.0000 0.0269 18627

tf 0.0067 0.0001 0.0222 0.0000 0.2435 18627

 

 Percentiles

----------------------------------------------------------------------------------------------

Variable 0.1% 1.0% 5.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 

-------- ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ 

bfr 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0001 0.0011 0.0070

ir 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0002 0.0011 0.0055 0.0277

 

 Correlations 

----------------------------------------------------------------------------------------------------------

Variable Precip ET sm bfi bfr bf gsnk ir if ovf tf

-------- ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ 

Precip 1.0000 0.0190 0.1220 0.2737 0.1994 0.1994 0.1994 0.1770 0.1095 0.7623 0.2152

ET 0.0190 1.0000 0.1993 0.1543 0.1940 0.1940 0.1940 0.2929 0.3035 0.1100 0.2522

sm 0.1220 0.1993 1.0000 0.3737 0.4313 0.4313 0.4313 0.4045 0.4017 0.1448 0.4550

bfi 0.2737 0.1543 0.3737 1.0000 0.9458 0.9458 0.9458 0.6354 0.5634 0.3561 0.8822

bfr 0.1994 0.1940 0.4313 0.9458 1.0000 1.0000 1.0000 0.7340 0.6926 0.2569 0.9630

bf 0.1994 0.1940 0.4313 0.9458 1.0000 1.0000 1.0000 0.7340 0.6926 0.2569 0.9630

gsnk 0.1994 0.1940 0.4313 0.9458 1.0000 1.0000 1.0000 0.7340 0.6926 0.2569 0.9630

ir 0.1770 0.2929 0.4045 0.6354 0.7340 0.7340 0.7340 1.0000 0.9832 0.2532 0.8855

if 0.1095 0.3035 0.4017 0.5634 0.6926 0.6926 0.6926 0.9832 1.0000 0.1617 0.8586

ovf 0.7623 0.1100 0.1448 0.3561 0.2569 0.2569 0.2569 0.2532 0.1617 1.0000 0.2857

tf 0.2152 0.2522 0.4550 0.8822 0.9630 0.9630 0.9630 0.8855 0.8586 0.2857 1.0000
116 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

Comparison of estimates for ground-water 

withdrawals made for domestic wells to simulated 

results for the entire watershed contents of the baseflow reservoirs indicates that, on a watershed basis, 

there is typically more than enough water in storage 

to meet estimates of contemporary (2001) demands 

for withdrawals. In fact, the daily time series of 

watershed contents in the base-flow reservoirs indicates that requirements for daily estimated withdrawals (0.0012 to 0.0018 inch) are exceeded 

greater than 99.9 percent of the long-term simulation period (table 32A). Intrawatershed estimates 

indicate that the minimum contents for base-flow 

reservoirs for the fault-zone rocks and Pikes Peak 

Granite always exceed estimated withdrawals. The 

contents for base-flow reservoirs in the metamorphic and intrusive rocks, however, are frequently 

between 50 and 60 percent for metamorphic rocks 

and about 80 percent for granitic rocks (table 32), 

less than estimates for daily withdrawals. Although 

water associated with base flow appears to be 

adequate to maintain current estimated withdrawals 

in the Pikes Peak Granite and fault-zone areas, the 

simulated results indicate that this is not the case in 

the metamorphic and intrusive rock areas of the 

watershed.

Table 32. Summary statistics of daily values for water-balance terms from long-term simulations for 

(A) the entire Turkey Creek watershed and areas of (B) metamorphic, (C) intrusive, and (D) fault-zone 

rocks and (E) Pikes Peak Granite—Continued

[All univariate statistics and percentiles reported in inches; Precip, total precipitation;

ET, total evapotranspiration; sm, contents of soil-zone reservoir at end of given period;

 bfi, total water added to base-flow reservoir; bfr, contents of base-flow reservoir at end

 of accounting period; bf, total base flow discharged to stream; gsnk, total water lost from

 base-flow reservoir that is not available to support local streamflow; ir, contents of 

 interflow reservoir at end of the accounting period; if, total interflow; ovf, total overland 

 flow; tf, total watershed flow; Min, minimum; Max, maximum, Stddev, standard deviation; N,

 number of observations; %, percentage]

 D. Fault-zone rocks

 

 Univariate statistics 

-------------------------------------------------------------------- 

 

Variable Mean Median Stddev Min Max N 

-------- ------ ------ ------ ------ ------ ---- 

Precip 0.0469 0.0000 0.1461 0.0000 2.6500 18627

ET 0.0392 0.0246 0.0409 0.0000 0.2207 18627

sm 2.1868 2.1627 0.7770 0.1428 3.9116 18627

bfi 0.0025 0.0000 0.0088 0.0000 0.0728 18627

bfr 1.6690 1.7157 0.5955 0.3865 3.4256 18627

bf 0.0009 0.0009 0.0003 0.0002 0.0019 18627

gsnk 0.0015 0.0015 0.0005 0.0003 0.0030 18627

ir 0.0297 0.0000 0.0889 0.0000 1.1633 18627

if 0.0050 0.0000 0.0158 0.0000 0.2230 18627

ovf 0.0002 0.0000 0.0010 0.0000 0.0263 18627

tf 0.0062 0.0012 0.0160 0.0002 0.2242 18627

 

 Percentiles

----------------------------------------------------------------------------------------------

Variable 0.1% 1.0% 5.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 

-------- ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ 

bfr 0.3945 0.4774 0.6101 0.7990 1.1068 1.3728 1.5653 1.7157 1.8648 2.0097 2.1765 2.4059

ir 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0006 0.0040 0.0191 0.0818

 

 Correlations 

----------------------------------------------------------------------------------------------------------

Variable Precip ET sm bfi bfr bf gsnk ir if ovf tf

-------- ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ 

Precip 1.0000 0.0196 0.1343 0.2725 0.0163 0.0163 0.0163 0.1737 0.1109 0.7735 0.1583

ET 0.0196 1.0000 0.2048 0.1965 0.1702 0.1702 0.1702 0.3498 0.3457 0.1116 0.3508

sm 0.1343 0.2048 1.0000 0.4270 0.2038 0.2038 0.2038 0.4789 0.4576 0.1539 0.4643

bfi 0.2725 0.1965 0.4270 1.0000 0.1046 0.1046 0.1046 0.7435 0.6784 0.3613 0.6927

bfr 0.0163 0.1702 0.2038 0.1046 1.0000 1.0000 1.0000 0.1724 0.1744 0.0277 0.1939

bf 0.0163 0.1702 0.2038 0.1046 1.0000 1.0000 1.0000 0.1724 0.1744 0.0277 0.1939

gsnk 0.0163 0.1702 0.2038 0.1046 1.0000 1.0000 1.0000 0.1724 0.1744 0.0277 0.1939

ir 0.1737 0.3498 0.4789 0.7435 0.1724 0.1724 0.1724 1.0000 0.9863 0.2421 0.9896

if 0.1109 0.3457 0.4576 0.6784 0.1744 0.1744 0.1744 0.9863 1.0000 0.1574 0.9979

ovf 0.7735 0.1116 0.1539 0.3613 0.0277 0.0277 0.0277 0.2421 0.1574 1.0000 0.2186

tf 0.1583 0.3508 0.4643 0.6927 0.1939 0.1939 0.1939 0.9896 0.9979 0.2186 1.0000
SUMMARY 117

SUMMARY

The Turkey Creek watershed has a drainage area 

of 47.2 square miles and lies southwest of Denver in 

the foothills of the Rocky Mountains at elevations 

between about 6,000 and 10,500 feet. The watershed 

has about 11,000 residents that occupy about 4,900 

households—a density of about one household per 

6 acres. Domestic water is derived from local ground 

water, and the majority of residents obtain water from 

household wells completed in fractured crystalline 

rock. Most withdrawn water is returned to the groundwater system through ISDS’s. 

Geology in the watershed consists of many types 

of Precambrian fractured metamorphic and intrusive 

crystalline rocks that have been deformed by folds and 

faults to produce many brittle features in the watershed; 

water contained in these rocks occurs dominantly in 

fractures. The many different types of rocks can be 

combined into three groups (metamorphic, intrusive, and 

their faulted equivalents) and a fourth subgroup (Pikes 

Peak Granite) that have unique fracture characteristics.

Direct measurements of evapotranspiration made 

at two sites in the watershed representing forest and 

meadow environments indicate that a large amount of 

Table 32. Summary statistics of daily values for water-balance terms from long-term simulations for 

(A) the entire Turkey Creek watershed and areas of (B) metamorphic, (C) intrusive, and (D) fault-zone 

rocks and (E) Pikes Peak Granite—Continued

[All univariate statistics and percentiles reported in inches; Precip, total precipitation;

ET, total evapotranspiration; sm, contents of soil-zone reservoir at end of given period;

 bfi, total water added to base-flow reservoir; bfr, contents of base-flow reservoir at end

 of accounting period; bf, total base flow discharged to stream; gsnk, total water lost from

 base-flow reservoir that is not available to support local streamflow; ir, contents of 

 interflow reservoir at end of the accounting period; if, total interflow; ovf, total overland 

 flow; tf, total watershed flow; Min, minimum; Max, maximum, Stddev, standard deviation; N,

 number of observations; %, percentage]

 E. Pikes Peak Granite

 

 Univariate statistics 

-------------------------------------------------------------------- 

 

Variable Mean Median Stddev Min Max N 

-------- ------ ------ ------ ------ ------ ---- 

Precip 0.0469 0.0000 0.1461 0.0000 2.6500 18627

ET 0.0353 0.0202 0.0402 0.0000 0.2217 18627

sm 1.3478 1.3099 0.5676 0.1316 2.2431 18627

bfi 0.0088 0.0000 0.0328 0.0000 0.2587 18627

bfr 3.1366 3.0133 1.2973 0.6440 7.9146 18627

bf 0.0017 0.0017 0.0007 0.0004 0.0044 18627

gsnk 0.0069 0.0066 0.0029 0.0014 0.0174 18627

ir 0.0244 0.0000 0.0858 0.0000 1.2981 18627

if 0.0027 0.0000 0.0096 0.0000 0.1574 18627

ovf 0.0002 0.0000 0.0008 0.0000 0.0214 18627

tf 0.0046 0.0019 0.0099 0.0004 0.1598 18627

 

 Percentiles

----------------------------------------------------------------------------------------------

Variable 0.1% 1.0% 5.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% 70.0% 80.0% 90.0% 

-------- ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ 

bfr 0.6562 0.7912 1.3022 1.5466 1.9813 2.3316 2.6641 3.0133 3.3711 3.7289 4.1855 4.8865

ir 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0004 0.0070 0.0585

 

 Correlations 

----------------------------------------------------------------------------------------------------------

Variable Precip ET sm bfi bfr bf gsnk ir if ovf tf

-------- ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ ------ 

Precip 1.0000 0.0219 0.1290 0.3039 0.0292 0.0292 0.0292 0.2090 0.1331 0.7127 0.1853

ET 0.0219 1.0000 0.1807 0.2865 0.2435 0.2435 0.2435 0.3788 0.3811 0.1192 0.3937

sm 0.1290 0.1807 1.0000 0.3516 0.0843 0.0843 0.0843 0.3067 0.2964 0.1467 0.3028

bfi 0.3039 0.2865 0.3516 1.0000 0.1230 0.1230 0.1230 0.6313 0.5526 0.3956 0.5714

bfr 0.0292 0.2435 0.0843 0.1230 1.0000 1.0000 1.0000 0.2327 0.2373 0.0639 0.3054

bf 0.0292 0.2435 0.0843 0.1230 1.0000 1.0000 1.0000 0.2327 0.2373 0.0639 0.3054

gsnk 0.0292 0.2435 0.0843 0.1230 1.0000 1.0000 1.0000 0.2327 0.2373 0.0639 0.3054

ir 0.2090 0.3788 0.3067 0.6313 0.2327 0.2327 0.2327 1.0000 0.9801 0.2930 0.9830

if 0.1331 0.3811 0.2964 0.5526 0.2373 0.2373 0.2373 0.9801 1.0000 0.1904 0.9946

ovf 0.7127 0.1192 0.1467 0.3956 0.0639 0.0639 0.0639 0.2930 0.1904 1.0000 0.2652

tf 0.1853 0.3937 0.3028 0.5714 0.3054 0.3054 0.3054 0.9830 0.9946 0.2652 1.0000

----------------------------------------------------------------------------------------------------------- 
118 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

precipitation in the Turkey Creek watershed is returned 

to the atmosphere. At the forest site, where evapotranspiration was sometimes limited by water availability, 

the mean evapotranspiration for 3 calendar years of 

measurements beginning in 1999 was 82.9 percent 

of measured precipitation; during a relatively dry 

calendar year (2000) evapotranspiration was as much as 

95.4 percent of measured precipitation. At the meadow 

site, where evapotranspiration was not often limited by 

water availability, calendar year 2001 evapotranspiration was about 1.2 times as much as at the forest site 

and, due to augmentation by shallow ground water, 

exceeded measured precipitation. The results of daily 

evaluations of evapotranspiration and related processes 

indicate that water can percolate to below the soil zone 

most effectively in the spring when evapotranspiration 

rates are low.

Surface-water records for Turkey Creek near 

the mouth of the canyon, through 2001, indicate that 

streamflow in the watershed is seasonal due to precipitation and snowmelt in spring. Although streamflow 

generally recedes to less than about 1 cubic foot per 

second later in the year, Turkey Creek is rarely dry. 

Short-term streamflow records collected at four 

subbasins that represent intrusive and fault-zone 

rocks and Pikes Peak Granite during the spring of 

2001 indicate that (1) intrusive-rock areas of the 

watershed generally have poorly sustained streams 

that frequently go dry during rainless periods and 

(2) areas of Pikes Peak Granite and fault-zone rocks 

have well-sustained streamflow. Synoptic measurements of streamflow made at many sites in the watershed during the summer and fall 2001 corroborate 

these findings and are the basis for characterizing 

metamorphic areas as having poorly sustained 

streamflow.

Ground-water-level measurements collected 

historically (from about 1973 through 1983), 

monthly beginning in 1998, continuously beginning 

in May 2001, and synoptically in September 2001, 

indicate a ground-water system that responds directly 

to precipitation. Historical measurements in USGS 

monitoring wells indicate a seasonal pattern, similar 

to surface water, in which ground-water levels rise in 

the spring and then steadily recede to about consistent 

levels annually. Contemporary measurements from the 

same USGS monitoring wells do not indicate a longterm downward trend in water levels; rather, annual low 

water levels are determined by the length of rainless 

periods. Additional contemporary water-level measurements indicate that water levels in some wells can 

fluctuate many tens of feet on an annual basis. Results 

from synoptic water-level measurements made in 

September 2001 indicate a water-table surface that is 

similar to the watershed topography. The synoptic data 

indicate a mean depth to water of about 105 feet; 

however, in the parts of the watershed where topographic relief is large, depths to water may exceed 

300 ft. 

Water quality was evaluated principally on the 

basis of samples from about 110 wells and 22 streams 

collected on a nearly quarterly basis during water 

year 1999; samples were analyzed for major ions, 

nutrients, and minor elements. These data indicate 

that ground water and surface water in the Turkey 

Creek watershed are calcium-bicarbonate to calciumchloride types of water that rarely fail to meet applicable Federal or State recommended drinking-water 

standards. However, concentrations for some waterquality properties and constituents in ground water, 

such as specific conductance, calcium, magnesium, 

sodium, chloride, and nitrate plus nitrite, appear to 

have increased significantly since the last similar 

sampling effort of ground-water quality in the 1970’s. 

In addition, concentrations for chloride in ground 

water and surface water, together with regional 

measurements of chloride in precipitation and a few 

samples that describe bromide concentrations in 

ground and surface water, indicate that water in the 

Turkey Creek watershed is being affected by residential development in the watershed. The likely source of 

these effects is from salt-containing traction materials 

used on roads, or effluent from ISDS’s, or both.

Water-quality sampling and analyses conducted 

in an effort to determine the extent, if any, of ISDS 

influence on water quality did not produce definitive 

results. Correlations among potential ISDS-related 

water-quality properties and constituents such as 

specific conductance, chloride, nitrate plus nitrite, 

and boron are not consistently strong and do not 

identify a single, simple process involved in the 

genesis of Turkey Creek watershed water quality. 

Reconnaissance-level samples of ground and surface 

water in 2001 that were analyzed for wastewater 

compounds indicate that some wastewater compounds 

are present in ground and surface water, perhaps with a 

higher incidence in surface water. On the basis of this 

study, it is not possible to determine if ISDS effluent 

is, or is not, a strong contributor to either ground-water 

or surface-water quality. Additional questions 

regarding preferential flow paths for ISDS effluent 

remain unanswered.
SUMMARY 119

An additional reconnaissance-level sampling 

effort, conducted by the Jefferson County Health 

Department, obtained analyses of tritium content from 

24 ground-water samples. The results of these samples 

indicate that some ground water in the Turkey Creek 

watershed was recharged before the nuclear testing era 

of the 1950’s and 1960’s; however, most water appears 

to be of recent age. 

Spatial distributions of water-quality properties 

and constituents such as specific conductance, chloride, 

nitrate plus nitrite and boron, have few definitive 

patterns. However, the southwestern part of the Turkey 

Creek watershed, which is topographically similar 

to other parts of the watershed, has the lowest concentrations of these water-quality properties and constituents. Supporting this finding are differences in medians 

at greater than 90-percent significance (p < 0.10) 

between water-quality properties and constituents, 

including specific conductance, all major cations, 

chloride, sulfate, and nitrate plus nitrite, determined for 

water from the Pikes Peak Granite in the southwest part 

of the watershed compared to the rest of the watershed. 

The relatively low concentrations in the Pikes Peak 

Granite are most likely a function of dilution, related to 

the relatively large amounts of ground water estimated 

to be present in the southwestern part of the watershed.

A methodology involving fracture-network 

analysis, watershed runoff modeling, and knowledge 

of hydrologic conditions was undertaken to assess the 

quantity of ground water in the watershed. Estimates 

of potential porosity were made for the four rock 

groups defined on the basis of geologic mapping and 

detailed analysis of outcrop-scale measurements of 

fracture characteristics. The estimates of potential 

porosity are very small, indicating that the fractured 

bedrock aquifer has a small amount of space in which 

water can exist. The magnitude of the porosity estimates is in the hundredths to tenths of a percent range 

for metamorphic and intrusive rocks and in range of 1 

to 9 percent for the fault-zone rocks. 

Knowledge of hydrologic conditions in the watershed was used with additional intrawatershed measurements of precipitation and temperature to calibrate a 

physically based, distributed-parameter runoff model 

(PRMS). The runoff model characterization of the rock 

groups as interflow and base-flow reservoirs facilitates 

watershed and intrawatershed estimates of ground water 

associated with streamflow. The runoff model characterization also uses a term (GSNK) to track losses from 

base-flow reservoirs—water that is lost from the baseflow reservoirs is ground water that is not associated 

with local streamflow. The initial runoff model calibration was adjusted on the basis of detailed evapotranspiration measurements available from two sites within the 

watershed, and the final calibration produces a good 

match between simulated and measured streamflow and 

a close match between simulated and measured runoff 

and evapotranspiration. 

Contemporary watershed model simulations 

for the period January 1, 1999, through September 30, 

2001, indicate that, on the entire watershed scale, 

there is typically more than enough ground water 

in base-flow reservoirs to meet estimates of daily 

ground-water withdrawals made for domestic supply. 

Intrawatershed conditions, however, vary. Watershed 

model estimates indicate that the Pikes Peak Granite 

and fault-zone areas receive recharge and transmit it 

to streamflow in a relatively consistent fashion; as a 

result, there is nearly always (greater than 99.9 percent 

of time, table 29) enough recoverable ground water in 

base-flow reservoirs to support estimates of daily 

ground-water withdrawals made for domestic supply. 

This is not the case, however, in the metamorphic and 

intrusive rock areas where field measurements indicate 

streams are poorly sustained and simulated results 

from the watershed model indicate that there is 

frequently (between 60 and 70 percent of the time 

for metamorphic and between 80 and 90 percent of 

the time for intrusive) not enough water in base-flow 

reservoirs to support estimates of daily ground-water 

withdrawals made for domestic supply. In these poorly 

sustained areas most recharge to the ground-water 

system is transmitted to streams quickly as base flow. 

When a base-flow reservoir becomes depleted there 

will be no base flow in the associated area, and ground 

water that is not associated with local streamflow 

becomes the only source of water available to wells. 

Once withdrawals from this source are replaced, or 

recharged, base flow in the watershed can resume. 

Long-term simulations from October 1, 1948, 

through September 30, 1999, were made using precipitation and temperature data from a climatologic 

station at Cheesman Reservoir in the vicinity of the 

Turkey Creek watershed. Long-term simulations were 

done to evaluate watershed conditions over a period of 

several decades by using climatic conditions that are 

similar to those in the Turkey Creek watershed. The 

results of the long-term simulations confirm that, on a 

watershed scale, the contents of base-flow reservoirs 

are consistently capable of meeting contemporary 

(2001) estimates of ground-water withdrawals made 
120 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed, 

Jefferson County, Colorado, 1998–2001

for domestic supply in the Turkey Creek watershed. 

The long-term results also indicate that the end-of-thewater-year contents of watershed base-flow reservoirs 

may be less than one-tenth of an inch under conditions 

of low annual precipitation (10 to 14 inches per year). 

In addition, the long-term simulations indicate that the 

watershed-scale recession for the watershed contents 

of the base-flow reservoirs can be as much as about 

0.06 inch per year during years with low precipitation. 

Together, these simulated results indicate that multiple 

years of low precipitation combined with relatively 

small amounts of water in base-flow reservoirs, a 

condition that is not present in the 51-year record of 

precipitation used for the long-term simulations, could 

deplete base-flow resources that support streamflow, 

at a watershed scale, in the Turkey Creek watershed. 

In this case the only source for domestic ground water 

in the watershed would be ground water that is not 

associated with local streamflow. The long-term 

simulations underpin the findings of the contemporary 

simulations that indicate ground water that supports 

base flow in the metamorphic and intrusive rock 

areas of the watershed is frequently depleted: between 

50 and 60 percent for metamorphic rocks and about 

80 percent for intrusive rocks. Although the longterm simulations indicate slightly higher estimates 

of annual accretions to ground-water storage not 

associated with streamflow, the magnitude of the longterm estimates are on the order of tenths of an inch. 

These observations reiterate the importance of ground 

water that is not associated with local streamflow to 

domestic water supply in the Turkey Creek watershed.

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Viger, R.L., Markstrom, S.L., and Leavesley, G.H., 1998, An 

interface for the treatment of spatial information used in 

watershed modeling and water resource management: 

Proceedings of the First Federal Interagency Hydrologic 

Modeling Conference, April 19–23, 1998, Las Vegas, 

Nevada, v. 2, p. 73–80.

Voss, C.I., 2000, Is simple analysis the best for complex 

environments?—Subsurface waste isolation in crystalline rock: 2000 Annual Meeting, Reno, Nevada, 

Geological Society of America Abstracts with 

Programs, v. 32, p. A–63.

Waltz, J.P., 1972, Methods of geologic evaluation of pollution potential at mountain homesites: Ground Water, 

v. 10, no. 1, p. 42–49.

Webb, E.K., Pearman, G.I., and Leuning, R., 1980, 

Correction of flux measurements for density effects 

due to heat and water vapour transfer: Quarterly 

Journal of Royal Meteorology Society, v. 106, 

p. 85–100.

Weeks, E.P., Weaver, H.L., Campbell, G.S., and Tanner, 

B.D., 1987, Water use by saltcedar and by replacement 

vegetation in the Pecos River flood plain between 

Acme and Artesia, New Mexico: U.S. Geological 

Survey Professional Paper 491–G, 33 p.

Wolock, D.M., 1997, STATSGO soil characteristics 

for the conterminous United States: accessed 

November 11, 2000, at URL http://water.usgs.gov/

GIS/metadata/usgswrd/muid.html
APPENDIX

APPENDIX 127

Brittle Structures of the Turkey Creek 

Watershed 

Figure 3 shows fracture network orientation 

data from nine localities collected along natural 

outcrops in the Turkey Creek watershed. The figure 

includes equal-area plots to indicate the strike, dip, 

and number of fractures mapped in a particular area. 

In the equal-area plots, orientation, or strike and dip, 

of a fracture is represented by a point; in figure 3 the 

points on the diagram have been contoured so that the 

darker the area the more points are represented. Points 

located near the edge of the diagram represent verticaldipping fractures and points near the center represent 

horizontal-dipping fractures. To determine the strike, 

or azimuth direction of a fracture, locate a point or 

center of a closed contour, locate a position 90 degrees 

clockwise, then go straight to the edge of the diagram 

and that azimuth positions the strike of the fracture; for 

reference, north is at the top of the diagram and east 

is at 90 degrees clockwise. Points or areas plotted 

between the outside and center of the diagram represent dip angles between 0 degrees, or horizontal 

(center), and 90 degrees, or vertical (edge). 

 Over 1,300 measurements of individual fractures were recorded, 1,066 were used in the fracture 

analysis (Caine, 2001). Of the measurements used, 

approximately 99 percent are joints, as indicated by 

the lack of striations, mullions, displaced compositional layers, and so forth. Most of the observed fractures are planar to slightly curviplanar in the intrusive 

rocks and slightly curviplanar to curviplanar in the 

metamorphic rocks. Many fractures, particularly in the 

intrusive rocks, have curving tips. The curvature may 

be critical in hydraulically linking otherwise planar 

and parallel fractures. In general, most fractures are 

short, a few meters in trace length. Aperture, the 

distance between the walls of a crack measured 

perpendicular to the walls, generally ranges from 

indistinguishable to several millimeters wide. There 

are rare apertures that are easily visible, weathered 

cracks, several centimeters wide. In general, most 

apertures were less than 1 millimeter wide. Most fractures in the intrusive rocks, and in many metamorphic 

rocks, are stained by iron oxides (field identified as 

hematite) that become diffuse a few millimeters to a 

few centimeters into the rock. Other mineral fillings 

are rare, so most of the observed joints are open fractures. Fracture intensities are on the order of 10 fractures per meter in the fault zones and pegmatite dikes 

to more typical values of 3 to 4 fractures per meter in 

the other rock groups. The term fracture intensity is 

used here as an indicator of how many fractures were 

observed in any given outcrop. Fracture spacing is 

relatively uniform in the intrusive rocks and pegmatites. In the metamorphic rocks and fault zones, local 

heterogeneities in composition, layer thickness, and 

proximity to preexisting structures have a large influence on fracture spacing, intensity, and orientation.

Fracture-set mean orientations and dispersions 

in the intrusive rocks are generally strongly clustered 

and thus have low dispersions (fig. 3). At two sites 

in the large central pluton in the watershed, Nobel 

and Harrington, generally similar fracture-set mean 

orientations are shown (fig. 3). In each case there is 

a subordinate fracture set steeply dipping northeastsouthwest, and a dominant northwest-southeast 

steeply dipping set (fig. 3). The Nobel site also has a 

northwest-southeast steeply dipping set of fractures. 

This site is very close to the pluton margin where the 

north-south set is roughly parallel to the contact with 

the metamorphic rocks (fig. 3). Other than the northsouth set, the similarity in mean orientation and 

dispersion, as well as other field indicators such as 

morphology, indicate that within individual plutons 

brittle fracturing of the intrusive rocks occurred rather 

uniformly. Computed fracture intensities in the intrusive rocks are quite uniform and range from 2.0 to 

2.5 m2/m3

 (see “Fracture Intensity and Calibration of 

Fracture Network Models to Field Data” section for 

discussion of how fracture intensity was derived).

Additional features observed in the intrusive 

rocks were small-scale (less than 1 m wide) fracture 

zones. These structures form localized and bounded 

zones of high-intensity fracturing relative to the 

surrounding rock. Fracture intensity in these zones is 

on the order of tens of fractures per meter in contrast 

to three to four fractures per meter in the surrounding 

rocks. The occurrence of fracture zones is on the order 

of one zone per approximately 7 to 12 meters. Because 

of the high fracture intensity of these zones relative to 

the surrounding rock, the zones may act as important 

localized areas of infiltration and aquifer recharge. In 

contrast, infiltration in the surrounding rock through 

very small-aperture, low-intensity fractures may be 

low. An additional heterogeneity found in the intrusive 

rocks is a myriad of dikes, wall and roof pendants, and 

other assorted apophyses that appear to vary randomly 

in scale and morphology. These features represent 

local (a few meters to hundreds of meters long) 

heterogeneities that have variably responded to 
128 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed,

Jefferson County, Colorado, 1998–2001

brittle deformation due to emplacement-related juxtaposition of metamorphic and intrusive rocks with a 

variety of rheological properties.

In contrast to the intrusive rocks, fracture sets 

in the metamorphic rocks exhibit a heterogeneity in 

orientation from one location to another (fig. 3). The 

fracture sets have moderate dispersion, and preexisting 

fabrics clearly have a large influence on orientation, 

intensity, and morphology. Computed fracture intensities also are heterogeneous and range from 1.6 m2

/m3

to 5.0 m2/m3 for the four localities studied. The metamorphic rocks exhibit a qualitative structural hierarchy 

of brittle fracturing that probably is controlled by 

primary and secondary features. Compositional 

layering and foliation also may influence fracture 

intensity and morphology. Variations in fracture 

intensity and morphology are highly scale-dependent. 

Picking a representative block of fractured rock of a 

particular type at a particular scale is difficult for this 

rock group.

Finally, there are many distinct styles of fault 

zones within the Turkey Creek watershed. Localized 

deformation zones composed of brecciated and mineralized host rock occur in one-kilometer-long, relatively 

narrow, curviplanar fault zones (fig. 3) where displacement of lithologic units can be documented. Although 

some of these features show very low intensities of 

fault-related subsidiary fracturing, most likely the initial 

brittle fractures were mineral filled in the early stages of 

faulting and subsequently assimilated into the fault 

zone, and they are locally jointed due to postfaulting 

deformation and (or) exhumation. These features likely 

act as partial localized barriers to ground-water flow in 

some subsurface locations but may also be shortcircuited by discrete jointing (Caine and Forster, 1999).

In contrast to the localized deformation zones 

are the unusually wide zones (tens of meters to more 

than several kilometers wide) of intense brittle fracturing and associated alteration (figs. 2 and 3). Fracture-network data were collected from two such fault 

zones where there was sufficient exposure along road 

cuts—the only data-collection localities that were 

not natural outcrops. The US40 fault-zone locality is 

outside of the watershed but is representative of wide 

fault zones within the watershed, such as the C73 

locality. The US40 locality is found in the Junction 

Ranch-Paradise Hills fault zone, and the C73 locality 

is found in the Conifer-Aspen Park fault zone (fig. 3). 

General observations also were made along several 

other road cuts in the watershed. Figure 3 shows that 

fracture orientations are diffuse and heterogeneous 

between the fault zones studied. Although there is 

fracture-network orientation heterogeneity within each 

fault zone, the overall style of fault-related fracturing 

is consistent within each of these fault zones. There 

are typically several sets of steeply dipping fractures 

and highly diffuse sets of subhorizontal fractures 

(fig. 3). Fracture trace lengths are generally short with 

mean values just over 0.5 m, and individual fractures 

most commonly truncate against other fractures to 

form a highly interconnected network. The fractures 

are commonly slightly curviplanar and have apertures 

typically less than 1 mm wide. Most of the fractures in 

the fault zones are stained by iron oxides (field identification indicates limonite) that have extensively 

migrated into the interfracture rock mass as either 

Liesengang bands (nested and fracture-symmetric 

bands or rings of higher and lower iron indicative of 

diffusion processes) or more massively diffused oxide 

staining. Computed fracture intensities also are consistent at the two fault zones studied and are on the order 

of 27 m2/m3

. These intensities are very high relative to 

other brittle structures.

Although no fracture-network data were 

collected in the pegmatite dikes, these features, 

which are meters up to about a kilometer long, are 

yet another heterogeneity that is superimposed on both 

the intrusive and metamorphic rocks in the watershed. 

One important and possibly significant observation 

is that the fracture intensity of these morphologically 

irregular features is about 10 times higher than the host 

rock into which they intrude, regardless of host rock 

type. It is not clear if the brittle fracturing is related to 

primary emplacement-related strain that was released 

during exhumation in the near subsurface, or to 

tectonic strains, or to some combination of both. 

Fracture Data Analysis, Model 

Construction, and Matching Models 

to Data

The flowchart in figure A1 summarizes the 

steps required for the comprehensive analysis and 

modeling of natural fracture data to generate input 

parameters for simulation of fracture porosity. A 

spreadsheet program, Stereonet (Allmendinger, 1995), 

and FracMan (Dershowitz and others, 1996) by Golder 

Associates, Inc., were the primary computer codes used 

for derivation of model parameters from the field data.
APPENDIX 129

The analyses used in this study assume that 

fracture sets with a mean orientation and dispersion can 

be distinguished from one another and that their individual physical properties control the hydraulic 

behavior of the fracture networks as a whole at a variety 

of scales. All other fracture-set parameters, such as trace 

length, are then calculated on a set-byset basis. Although natural fracture sets can be distinguished by a number of parameters, the sets assigned in 

this study are based exclusively on orientation. This is 

primarily due to the lack of unique mineralization 

signatures, age markers, and general uniformity of 

length and morphology in any given set. 

FracMan is a discrete fracture-network dataanalysis and synthetic fracture-network generator 

computer code. FracMan creates rectangular regions 

that are filled with synthetic fractures whose properties 

statistically relate to the field data. When constructing 

a fracture network, FracMan initially selects a fracture 

center point from a random number for the first fracture in the first fracture set. It then randomly selects an 

orientation and length from the statistical distribution 

for that set, assigns these values to a fracture, and 

randomly places the synthetic fracture in the specified 

model domain. The next fracture is created with a new 

center point, in a position defined by a fracture spacing 

model for that set. The above process is repeated until 

the first set has been completely created in accordance 

with the specified fracture intensity for that set. Each 

successive set is created until the fracture network is 

complete. Additionally, as each fracture in each set is 

created in the network, random fracture truncations 

and free tips are created in accordance with the field 

data for that set. Following is a description of how 

each fracture network parameter is developed for input 

into FracMan.

Fracture Set Designation

Raw orientation data are plotted on a lower 

hemisphere equal-area plot and then contoured using 

the Kamb method (Kamb, 1959, figure 13). Clusters 

of the raw and contoured data are segregated and 

the mean orientation and Fisher dispersion for each 

cluster (set) are calculated. The choice of any individual set is based on the tightness of the cluster and 

observations made in the field. Each fracture in each 

set and its corresponding data (for example, position, 

trace length, and terminations) are segregated to form 

a new set-specific, comprehensive database.

Figure A1. Flow chart showing how discrete 

fracture-network model parameters are modeled 

to lead to the construction of a single best-fit 

model.

0.1 1 10

FRACTURE TRACE LENGTH, IN METERS

Probability distribution

function (PDF)

2,500

2,000

1,500

1,000

500

0

FREQUENCY

B. Trace length

N=139 C.I.=2.0 σ

N

A. Orientation

C. Fracture intensity
130 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed,

Jefferson County, Colorado, 1998–2001

Fracture Length Simulation

The trace-length means, standard deviations, 

and probability distribution functions (PDF, the type 

of curve that best fits a parameter frequency distribution plot) are determined for each set from the raw 

data. A PDF is plotted for the raw trace-length data 

by using FracMan. Fracture termination style (for 

example, free tips and truncations by neighboring 

fractures or fractures that freely intersect other fractures) also is incorporated into the fracture-length 

distributions. In order to create a synthetic trace-length 

distribution and derive its mean and PDF that best 

matches the field data, simulated trace planes and 

scanlines are set up that have the same orientations 

and sizes as those in the field from which the data 

were collected (Dershowitz and others, 1996). 

Multiple simulations of fracture traces are generated 

with the code FracSize (a module of FracMan). The 

initial simulation is started with a mean fracture 

radius, standard deviation, and distribution based 

on the field data. Simulations are repeated until a satisfactory match between the simulated and measured 

fractures are obtained. The criteria for a good fit are 

arbitrarily based on the results of KolomogorovSmirnov (K-S) and Chi-squared (Chi2) tests 

(Dershowitz and others, 1996). For most simulations, 

90 percent or better significance was sought for both 

K-S and Chi2. Unfortunately, many of the data were 

difficult to fit at such high degrees of significance. The 

mean percent significance for all simulated fracture 

sets using K-S was 93.5 percent and using Chi2 was 

69.0 percent.

Fracture Spacing

Fracture spacing was assumed to be best 

represented by a uniform distribution. The Enhanced 

Baecher spacing model (Dershowitz and others, 1996) 

in FracMan was found to yield fracture-network 

models that best match the field observations. The 

Enhanced Baecher model locates fracture centers 

in a model domain using a Poisson distribution and 

allows for fracture terminations at intersections with 

preexisting fractures (Dershowitz and others, 1996). 

The Enhanced Baecher model produces fracture 

sets with relatively uniform spatial distributions and 

minimal clustering, as was generally observed in 

the field. All fractures in this study are simulated 

as smooth, parallel-walled, hexagonal plates.

Fracture Intensity and Calibration of Fracture 

Network Models to Field Data

Fracture intensity can be expressed as fracture 

area per unit volume (that is, m2

/m3 = 1/m, or P32 in 

FracMan). The term fracture density is sometimes 

interchanged with fracture intensity, which is more 

formally defined here as the number of fractures per 

unit line length (that is, 1/m, or P10 in FracMan). 

Because fracture-dominated fluid flow and fracture 

intensity occur in a three-dimensional volume, threedimensional modeling is appropriate in this case. 

Because fracture intensity in a volume cannot be 

directly measured, it can only be simulated from scanline fracture intensity or P10 data. Because the dimensions of fracture area per unit volume (P32) and 

number of fractures per unit line length (P10) are the 

same (that is, 1/length), P32 can be derived from P10. 

Fracture intensity is estimated by matching, or calibrating, simulated fracture lengths and intensities to 

the field data.

First, a three-dimensional, cubic simulation 

region or model domain is defined using FracMan 

for each locality that is slightly larger than the longest 

scanline measured in the field at that locality. There 

were at least three and up to nine scanlines measured 

at each locality. Within the model domain, the three 

most orthogonal scanlines are simulated. These are 

simulated with the same orientation and length as 

those measured in the field, and the positions of the 

simulated and measured scanlines in the domain are 

assumed to be random as are the actual scanlines in 

the field. Model P10’s are then calculated for each 

fracture set on each scanline by running Monte Carlo 

simulations using an initial supplied value for P32

(usually starting with the observed P10 value). This is 

repeated using a Monte Carlo-style simulation process 

until the input P32 value results in a close match to the 

observed P10. A close match is determined by calculating the relative error for each simulation. Thus, 

for each of 100 realizations of a fracture network 

constructed with the same statistical parameters but 

a different initial seed, the resulting number of simulated fracture intersections (Mi) with each model 

scanline is compared with the observed number of 

intersections (Oi) from the real scanlines. The relative 

percent error (Mi–Oi/Oi ×100) is then calculated for 

each run, and the input P32 is adjusted until the error 

is arbitrarily less than 10 percent.
APPENDIX 131

The next step in the process is to further 

adjust P32 using all of the fracture sets in the full 

model domains and the three most orthogonal scanlines for the location being simulated. All nonfaultzone model domains are 15-m cubes. The fault-zone 

model domains are 2-m cubes. Once reasonable estimates of fracture density (P32) are derived from the 

scanline fracture-intensity data (P10) matching process 

described above, a similar process of populating 

the full model domains with all fracture sets can be 

started. A first estimate for the P32 for each fracture 

set is again run 100 times using a Monte Carlo-style 

simulation. The number of intersections for each simulated fracture set on each scanline is compared with 

the observed data, and the mean relative error is again 

calculated for all of the 100 realizations. The P32’s are 

then systematically adjusted, within reasonable values 

compared to the field data, until the mean relative error 

for each scanline is arbitrarily within about 20 percent 

of the observations.

For most of the simulations the full-model, 

single scan-line calibrations are well within 

20 percent mean relative error. However, there are 

several fracture-set P32 outliers that would not calibrate to within 20 percent. Because this study is 

designed to generate fracture-network models that 

generically represent the field data, the results are 

acceptable. Moreover, the final step in this process 

is to choose the best single fracture-network model 

generated by one random seed, which has the lowest 

relative percent error. For each of the models, the 

error for simulated fracture sets along each model 

scanline is within 20 percent, and generally less 

than 10 percent, and the mean total error for all of 

the models is 3.7 percent. The best model for each 

location was saved and used for calculating fracture 

porosity scenarios as described in the “Estimates of 

Potential Fracture Network Porosity” section. 

Spatial Analysis of Well-Construction 

Data and Ground-Water Levels

A brief analysis of spatial characteristics for 

reported well yield was done to determine if the 

available data were sufficient to define any spatial 

patterns in aquifer characteristics. The analysis 

included geostatistical techniques that can be referred 

to as “variogram analysis.” Variogram analysis is a 

precursor to techniques that use existing measurements to estimate conditions at unmeasured locations. 

Detailed descriptions of variogram mechanics are 

available in texts (Isaaks and Srivastava, 1989; 

Cressie, 1991), and only the general nature of such 

analysis is discussed here.

An essential goal of variogram analysis is 

to evaluate the spatial association for, in this study, 

reported well yields. The analysis helps answer the 

question, “In general, are the reported yields for wells 

that are closely located to each other more similar than 

the reported yields for wells that are not closely 

located?” A convenient way to evaluate spatial association is to compute differences in reported yields for 

all possible pairings of wells, and then to express variability of the computed differences, often in a graph 

called a variogram, as a function of the distance 

between wells. For example, wells that are close 

to each other may have relatively small differences 

in reported yields, and the variability of differences 

in reported yields is relatively low. As the distance 

between wells increases, differences in reported 

yields may increase, which will reflect an increased 

variability. 

In the example above, the initial values on a 

variogram (those for wells with very small separation 

distances) would indicate a minimum value. As the 

separation distance increases, the variogram value 

rises to the maximum value for variability and may 

remain at a relatively constant value. The minimum 

variogram value, commonly called a nugget, represents the expected amount of variability in reported 

yields for closely spaced wells. The maximum value, 

commonly called the sill, represents the expected 

amount of variability for relatively large well spacings. 

The value for well spacing associated with the sill, 

commonly called the range, is an approximation of the 

largest well spacing for which the members of a pair of 

wells have some amount of spatial association. If the 

observed variability for pairs is influenced by direction, it is useful to develop graphical representation for 

a series of variograms that describe spatial association 

and the way it varies with direction. This graphical 

representation is called a variogram surface map. The 

variogram surface map can be thought of as a representation of a series of variograms made through a full 

circle of directions.
132 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed,

Jefferson County, Colorado, 1998–2001

Evapotranspiration Measurement 

Methods

The eddy-correlation method, used at the forest 

site, does not rely on the surface energy balance but uses 

direct measurements of the turbulent eddy motions and 

the water or heat content of the eddies above a plant 

canopy to compute E and H (Swinbank, 1951). 

Although movement of air (wind) is primarily horizontal, vertical motions of parcels, or eddies, of air 

are superimposed on the overall horizontal movement. 

Transport of any constituent (water, heat, carbon 

dioxide, pollutants) between the surface and the 

atmosphere occurs through these vertical motions. 

For example, if evaporation is occurring, then on 

average, upward-moving eddies are more humid than 

downward-moving eddies. Sensible heat flux is the heat 

that moves between the surface and the atmosphere due 

to a temperature difference. And if sensible heat is 

moving upward, then on average, upward-moving 

eddies are warmer than downward-moving eddies. By 

making very rapid measurements of vertical windspeed 

and concentration (vapor density, temperature, and so 

forth) at a point, many eddies are sampled and the data 

reflect the mean fluxes from the underlying surface. 

Mathematically, these ideas can be written as:

(A1a)

and

(A1b)

where

E is the mass flux of water vapor (grams per 

square meter per second),

H is sensible heat flux (watts per square 

meter),

w is the vertical component of windspeed 

(meters per second), 

ρv is vapor density (grams per cubic meter),

ρ is air density (grams per cubic meter), 

Cp is the specific heat capacity of air (joules 

per gram per degree Celsius),

T is air temperature (degrees Celsius), and 

primes (') denote deviations from means over some 

time period.

In this formulation, overbars ( ) denote means 

over the same time period, is the covariance of 

w and ρv, and is the covariance of w and T. At 

the forest site, w', ρv', and T' were sampled eight times 

per second and the covariances were calculated every 

30 minutes on a digital data logger. A sonic anemometer was used to measure w' and T' , and a krypton 

hygrometer was used to measure ρv'. Eddy correlation 

sensors were placed at 57 ft above land surface on a 

60-ft-tall tower; mean tree height was 39 ft. Placement 

of the sensors well above the canopy (about 1.5 times 

canopy height) ensures that small-scale variability in 

the turbulent flow field, caused by spacing between 

individual trees, is removed. Corrections were made to 

the raw measurements to account for density effects 

(Webb and others, 1980) and for the sensitivity of the 

krypton hygrometer to oxygen (Tanner and Greene, 

1989). Also, coordinate rotation was applied to 

account for the slight slope (3.75°) at the site (Kaimal 

and Finnigan, 1994). At an ideal site, accuracy of 

eddy-correlation measurements is considered to be 

about 5 to 10 percent on a daily time step and about 2 

to 3 percent on a monthly time step (Shuttleworth and 

others, 1988). Values of E in grams per square meter 

per second can be converted to ET rates in inches per 

day by multiplying by 3.402.

Eddy-correlation sensors do not operate when 

their sensing surfaces become wet during or after 

precipitation. When these surfaces dry out, the 

measurements resume. During the 3 years of study, 

the eddy-correlation sensors were inoperative (down) 

16.2 percent of the time (which was about evenly 

divided between day time and night time). If sensors 

were down for more than two consecutive 30-minute 

periods, ET was estimated using a modified PriestleyTaylor equation for potential ET (Priestley and Taylor, 

1972). Potential ET occurs from a wet or “wellwatered” surface. It was reasoned that if sensors were 

wet for an extended period, the forest canopy was in 

all likelihood also wet and potential ET was occurring. 

The Priestley-Taylor equation is driven by net radiation, soil heat flux, and air temperature. If sensors 

were down for one or two 30-minute periods, H and

LE were simply set to their respective values from the 

last 30-minute period before they went down. These 

short downtimes are often associated with very brief 

showers, where canopy surfaces may remain mostly 

dry but a single raindrop or snowflake can render the 

E w'ρv = '

H = ρCpw'T '

w'ρv'

w'T '
APPENDIX 133

sensor(s) inoperative. A potential ET estimate is inappropriate during these times, whereas an estimate from 

about an hour earlier is justified.

Net radiation, Rn, soil heat flux, G, and change 

in heat stored in the canopy, ∆S, also were measured 

at the forest site to provide a check on the eddycorrelation measurements. If all measurements are 

accurate, then the left side of equation 1 (in text) 

will equal the right side. If the two sides are unequal, 

the difference is the energy-balance closure. Rn was 

measured using a Radiation Energy Balance Systems 

(REBS), Inc., model Q*7.1 net radiometer, placed 

at 53.4 ft above land surface (14 ft above the treetops). 

The sensor was located south of the tower about 

5.8 ft from the nearest tower leg and was maintained 

level. Corrections were made to the raw measurements 

to account for the sloping surface at the site (Nie 

and Kanemasu, 1989) and for the effects of windspeed 

(REBS, 1995). G was measured using the combination 

method (Fuchs and Tanner, 1968). Three soil-heat 

flux plates were buried at a depth of 3.1 inches to 

measure the flux of heat at this depth, Gd. Three sets 

of four thermocouples were buried at depths of 0.4, 

1.2, 2.0, and 2.8 inches to measure the mean temperature of the soil from the surface to the 3.1-inch depth. 

These temperatures were used with estimates of the 

specific heat capacity of the soil (Cs) to calculate 

∆ST, the change in heat stored in the 3.1-inch layer. 

The soil heat flux at the surface, G, was calculated 

as the sum of Gd and ∆ST. Cs was computed from 

measurements of bulk density and water content 

of the soil. A few volumetric soil samples were 

obtained to measure bulk density, and water content 

(soil moisture) was measured onsite every 30 minutes

G is a small but significant term in the energy balance 

of the forest on a 30-minute basis, but G is very near 

zero on a daily basis because heat that penetrates 

the soil during the day typically is liberated back 

to the atmosphere at night. Although measurements 

to calculate ∆S were made at this site, the calculation 

requires information about forest biomass and distribution that has not yet been determined. Because 

∆S typically is smaller than G on a daily basis, it 

was not calculated in this report and was assumed 

to be zero.

Accuracy of eddy-correlation measurements 

often is difficult to assess because independent 

measurements of the turbulent fluxes (H and LE) 

usually are not made concurrently. In wildland 

settings, usually the only guideline available to estimate the accuracy of eddy-correlation measurements 

is the energy-balance closure. However, this is not 

always conclusive because errors may exist in any of 

the terms in equation 1. Over periods of a day or more, 

errors in G or ∆S are likely to be very small because 

the terms themselves are small. Rn is the largest single 

term in equation 1, however, and could potentially 

contain significant errors. Comparisons were made 

between daily values of (Rn – G) and (H + LE) 

measured at the forest site, using only days when 

all sensors were operational (594 days). ∆S was 

not included because it is very small on a daily 

basis and is virtually zero averaged over the whole 

study period. On average, the turbulent flux (H + LE) 

was 80.05 percent of the available energy (Rn – G). 

Daily values of (H + LE) are well correlated with 

(r2 = 0.913) but significantly less than daily values of 

(Rn – G). This amount of disparity between available 

energy and turbulent flux is not uncommon (Moore, 

1976; Weeks and others, 1987; Fitzjarrald and others, 

1988; Bidlake and others, 1993; Goulden and others, 

1996; Sumner, 1996; German, 2000). Very good 

energy-balance closures have also been obtained 

at some sites, however (Anderson and others, 1984; 

Verma and others, 1986; Shuttleworth and others, 

1988; Stannard, 1993; Stannard and others, 1994; 

Baldocchi, 1994). There is ongoing debate regarding 

the reasons for lack of energy-balance closure. There 

are good reasons to believe that the model of net 

radiometer used in this study overmeasures net radiation (Campbell and others, 1978; G.S. Campbell, 

Washington State University, written commun., 1980), 

and there is little reason to suspect problems with the 

eddy-correlation method. Therefore, ET results for this 

forest site will be based on the raw eddy-correlation 

measurements, uncorrected for energy-balance 

closure. Until the energy-balance question is resolved, 

however, the possibility exists that these ET values 

significantly underestimate the true ET.

The Bowen-ratio method, used at the meadow 

site, relies on the assumption of zero energy-balance 

closure (eq. 1) to compute latent-heat flux, LE. The 

Bowen ratio, B, is the ratio of sensible to latent-heat 

flux, H/LE. If B can be measured along with Rn, G, 

and ∆S, equation 1 can be used to compute both H and 

LE. If the eddy diffusivities for heat and water vapor 
134 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed,

Jefferson County, Colorado, 1998–2001

are equal, then the ratio of the fluxes is equal to the 

ratio of the vertical gradients (or differences) in 

concentration (Bowen, 1926). Mathematically, this 

can be stated as:

(A2)

where 

B is the Bowen ratio (unitless),

γ is the psychrometric constant (kilopascals 

per degree Celsius), 

∆T is the vertical temperature difference over 

some interval above the plant canopy 

(degrees Celsius), and

∆e is the vertical vapor pressure difference over 

that same interval (kilopascals).

Using the definition of B from above, equation 1 

(in text) can be rewritten as:

(A3)

and LE can be divided by L to obtain E. 

Rn and G were measured at the meadow site 

using methods and sensor models identical to those 

used at the forest site. No attempt was made to 

measure ∆S at the meadow site because the biomass of 

the grass canopy is small enough that ∆S is insignificant. Measurement of ∆T and ∆e typically requires 

specialized methods to remove bias between upper 

and lower sensors because the differences often are 

of similar magnitude to sensor bias. For this study, 

sensor bias was removed by interchanging positions of 

the two sensors on regular intervals (Tanner, 1960) and 

averaging the readings. At the meadow site, two ventilated solid-state temperature-humidity probes were 

deployed at heights of 6.8 ft and 3.5 ft above land 

surface. Data were collected for 15 minutes, the probes 

were interchanged, and data were collected for another 

15 minutes. Assuming the bias between sensors 

remains constant over one-half hour, averaging the 

two 15-minute periods together to compute half-hour 

differences eliminates sensor bias. These differences 

were used to compute half-hour values of B by using 

equation A2 and half-hour values of LE by using 

equation A3. Bowen-ratio data were filtered following 

the method described in Ohmura (1982) to eliminate 

problems caused by small measurement errors near 

sunrise and sunset. If –0.7>B>–1.3, or computed H 

and LE were of opposite sign to ∆T and ∆e, respectively (that is, counter-gradient flux was indicated), 

then LE was set to zero. The raw measured values 

of daily ET at the meadow site were reduced by 

20.0 percent because net radiation, Rn, is used to 

calculate ET using the Bowen-ratio method (eq. A3 

in Appendix) and was believed to be overmeasured 

using this model of net radiometer. This adjustment 

is intended to remove ET measurement bias between 

the two sites caused by methodological differences. 

As with the eddy-correlation results, until the energybalance question is resolved, the possibility exists that 

the Bowen-ratio ET values significantly underestimate 

the true ET at the meadow site.

Quality Assurance and Quality Control

 The integrity of analytical and sampling procedures can be evaluated using milliequivalent balances, 

quality-control samples, and duplicate samples; about 

37 percent of all samples analyzed as part of this study 

were quality-control samples. Milliequivalent balances 

commonly are used to evaluate analytical integrity, 

whereas various quality-control samples are used to 

evaluate both analytical and sampling integrity.

Milliequivalent Balances

 Concentrations in milligrams per liter may 

be converted to milliequivalents by adjusting those 

concentrations for their formula weights and chemical 

charges. The resulting milliequivalent concentrations 

are used to compute milliequivalent balances by 

summing cation and anion milliequivalents and 

comparing those two sums. Assuming that cations and 

anions are the major contributors to the ionic content 

of sampled water, the two sums should be equal. The 

milliequivalent balance typically is computed with this 

equation:

(A4)

where Σc is the sum of the cation milliequivalent 

concentrations and Σa is the sum of the anion 

milliequivalent concentrations.

B γ

∆T

∆e = ------

LE

Rn–G – ∆S

1 + B = --------------------------

Σc – Σa

Σc + Σa

------------------------ × 100
APPENDIX 135

 A frequency table showing the distribution 

of milliequivalent balances for samples collected 

as part of this study (table A1) indicates that about 

88 percent of all samples for which milliequivalent 

balances are available are within plus or minus 

7.5 percent. These analyses represent the typical 

performance of the laboratories involved, when 

making analytical determinations for this study. 

Of the remaining 27 samples, 21 are dilute water (relatively low ionic content) that have no results for potassium. Because the samples are dilute, the absence of 

results for potassium may account for the apparent 

lack of balance. The remaining six samples represent 

results that are not well balanced, indicating that some 

of the major-ion results have higher than typical error 

bars.

Quality-Control Samples

 The validity of quality-control samples was 

ensured by using inorganic-free water provided by the 

USGS Ocala, Fla., laboratory (American Society for 

Testing Materials D1193, 1999). Detection of measurable concentrations for any water-quality constituent 

in quality-control samples indicates a possibility that

Table A1. Frequency distribution for milliequivalent 

balances

[Note: Interval, interval of milliequivalent balance values;

 Absolute frequency number of milliequivalent balances in 

 interval]

---------------------------------------------------------------

 Absolute Cumulative

 Absolute frequency frequency

 Interval frequency (percent) (percent)

---------------------------------------------------------------

 -22.5 - -20 2 0.905 0.905

 -20 - -17.5 0 0.000 0.905

 -17.5 - -15 3 1.357 2.262

 -15 - -12.5 2 0.905 3.167

 -12.5 - -10 8 3.620 6.787

 -10 - -7.5 6 2.715 9.502

 -7.5 - -5 13 5.882 15.385

 -5 - -2.5 32 14.480 29.864

 -2.5 - 0 41 18.552 48.416

 0 - 2.5 77 34.842 83.258

 2.5 - 5 29 13.122 96.380

 5 - 7.5 2 0.905 97.285

 7.5 - 10 1 0.452 97.738

 10 - 12.5 0 0.000 97.738

 12.5 - 15 1 0.452 98.190

 15 - 17.5 0 0.000 98.190

 17.5 - 20 0 0.000 98.190

 20 - 22.5 1 0.452 98.643

 22.5 - 25 0 0.000 98.643

 25 - 27.5 0 0.000 98.643

 27.5 - 30 0 0.000 98.643

 30 - 32.5 0 0.000 98.643

 32.5 - 35 0 0.000 98.643

 35 - 37.5 1 0.452 99.095

 37.5 - 40 1 0.452 99.548

 40 - 42.5 0 0.000 99.548

 42.5 - 45 1 0.452 100.000

 --------- --------

 Total 221 100.000

---------------------------------------------------------------

analytical or sampling procedures have introduced 

some error into reported concentrations. Table A2 lists 

results for quality-control samples in which measurable concentrations for water-quality constituents 

were detected. Results for all bacteriological samples 

collected in June 1999 were rejected due to the presence of total coliform bacteria in bacteriological 

blanks. No other data were rejected; however, some 

discussion of the detections in quality-control samples 

is warranted. 

The most commonly detected constituents 

in the quality-control samples are minor elements, 

and the most prominent of those detections are three 

reported detections of antimony at concentrations of 

about 50 μg/L using inductively coupled plasma (ICP) 

methods. In this study, the ICP method was used principally to detect cations; however, the method also 

provides results for minor elements. In this study, the 

atomic adsorption graphite furnace (AAGF) method 

was used to detect minor elements because it is generally known to be more sensitive to minor elements 

than ICP methods. For the three ICP detections of antimony at concentrations of about 50 μg/L, the AAGF 

results indicate no detectable antimony. The same 

is true for all other reported detections for minor 

elements in table A2 with ICP methodology. AAGF 

methodology did detect minor elements at low concentrations in 17 (or about 6 percent of AAGF qualitycontrol analyses) quality-control samples analyzed 

mostly in the fall 1998. No AAGF results were 

rejected as part of this study; however, the results for 

detections of minor elements at low concentrations 

with AAGF methodology indicates some uncertainty 

for AAGF concentrations.

Additional detections in quality-control 

samples involved nutrients. There were two detections 

of total phosphorus at 0.02 mg/L, a level that is the 

detection limit for methods used in this study. The low 

level and frequency for total phosphorus in qualitycontrol samples were noted but were not identified as 

cause to reject total phosphorus results. A detection of 

nitrate plus nitrite as nitrogen at a concentration of 

3.82 mg/L in a preservative blank was attributed to 

field error. 

Water for field blanks associated with the 

wastewater-compound analyses was obtained at the 

USGS NWQL. Sample bottles of blank water were 

kept open to the air during sample collection and 

processing to expose the field blank to the same potential sources of contamination as the environmental
136 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed,

Jefferson County, Colorado, 1998–2001

Table A2. List of detections in quality-control samples

[Note: Control number refers to unique number assigned to each sample by USEPA; Sample

 identifier defines type of quality control sample with characters 1-3 (QCA and QCD -

 equipment blanks, QCB - field blank, QCC and QCE - preservative blanks, QCX -

 bacteriological blank); Collection date is mmddyy (month, day, year); collection time is

 hhmm (hours, minutes); Analytical method, AAGF GROUP - atomic adsorption graphite

 furnace, ICP - inductively coupled plasma; Phase, D - dissolved; --, not available 

 or applicable; μg/L, microgram per liter]

--------------------------------------------------------------------------------------------

 Collection

 Control Sample ------------ Water-quality Analytical 

 number identifier date time constituent method Phase Result Units 

--------------------------------------------------------------------------------------------

 Equipment blanks (total collected = 112)

 

 8-183303 QCA-T1-1 091498 1216 TITANIUM ICP GROUP D 2.00 μg/L 

 8-183348 QCA-T2-2 091598 1441 TITANIUM ICP GROUP D 2.00 μg/L 

 8-183438 QCA-T3-2 091698 1025 LEAD AAGF GROUP D 1.00 μg/L 

 8-183326 QCD-T1-5 091898 1040 AMMONIA (as N) -- -- 0.05 mg/L 

 8-183446 QCD-T3-3 091898 1323 AMMONIA (as N) -- -- 0.08 mg/L 

 8-183416 QCD-T2-5 092198 1144 AMMONIA (as N) -- -- 0.05 mg/L 

 8-183418 QCA-T2-6 092298 1530 TITANIUM ICP GROUP D 1.00 μg/L 

 8-183338 QCA-T1-8 092398 1043 COPPER AAGF GROUP D 1.00 μg/L 

 8-183453 QCA-T3-5 092398 1101 ANTIMONY ICP GROUP D 53.0 μg/L 

 8-183601 QCA-SW-01 092498 1115 ARSENIC AAGF GROUP D 1.60 μg/L 

 8-172347 QCD-SW-2 031799 1045 TOTAL PHOSPHORUS -- -- 0.02 mg/L 

 8-182072 QCA-T3-5 062299 1345 SILVER AAGF GROUP D 0.20 μg/L 

 Field blanks (total collected = 38)

 8-183344 QCB-T2-1 091498 1255 TITANIUM ICP GROUP D 3.00 μg/L 

 8-183349 QCB-T2-2 091598 1441 TITANIUM ICP GROUP D 2.00 μg/L 

 8-183409 QCB-T2-4 091898 1035 ARSENIC AAGF GROUP D 1.00 μg/L 

 8-183334 QCB-T1-7 092298 1350 TITANIUM ICP GROUP D 1.00 μg/L 

 8-183419 QCB-T2-6 092298 1530 LEAD AAGF GROUP D 0.60 μg/L 

 8-183454 QCB-T3-5 092398 1101 ANTIMONY ICP GROUP D 50.0 μg/L 

 8-183454 QCB-T3-5 092398 1101 ARSENIC AAGF GROUP D 1.10 μg/L 

 8-183424 QCB-T2-7 092398 1345 TITANIUM ICP GROUP D 1.00 μg/L 

 8-183602 QCB-SW-01 092498 1115 LEAD AAGF GROUP D 0.70 μg/L 

 8-183616 QCB-SW-03 092998 1255 COPPER AAGF GROUP D 0.60 μg/L 

 8-182018 QCB-T1-2 061699 1215 COPPER AAGF GROUP D 0.70 μg/L 

 8-182028 QCB-T3-2 061699 1315 COPPER AAGF GROUP D 0.60 μg/L 

 Preservative blanks (total collected = 113)

 8-183442 QCE-T3-2 091698 1025 TOTAL PHOSPHORUS -- -- 0.02 mg/L 

 8-183310 QCC-T1-2 091598 1030 TITANIUM ICP GROUP D 3.00 μg/L 

 8-183437 QCE-T3-1 091598 1115 NITRATE/NITRITE (N) -- -- 3.82 mg/L 

 8-183350 QCC-T2-2 091598 1441 TITANIUM ICP GROUP D 3.00 μg/L 

 8-183450 QCC-T3-4 092198 1405 ANTIMONY AAGF GROUP D 0.60 μg/L 

 8-183450 QCC-T3-4 092198 1405 THALLIUM AAGF GROUP D 0.90 μg/L 

 8-183450 QCC-T3-4 092198 1405 ZINC ICP GROUP D 4.00 μg/L 

 8-183617 QCC-SW-03 092998 1255 ANTIMONY ICP GROUP D 48.0 μg/L 

 8-182079 QCC-T1-6 061499 1625 COPPER AAGF GROUP D 1.30 μg/L 

 8-182089 QCC-T3-6 061499 1615 COPPER AAGF GROUP D 1.20 μg/L 

 8-182009 QCC-T2-1 061599 1215 COPPER AAGF GROUP D 0.90 μg/L 

 8-182696 QCC-T1-7 062399 1045 CHROMIUM AAGF GROUP -- 1.30 μg/L 

 Bacteriological blanks (total collected = 26)

 8-170641 QCX-T1-7 062399 1045 Total Coliform -- -- 1 -- 

 8-182532 QCX-T2-7 062399 1140 Total Coliform -- -- 1 -- 

 8-182533 QCX-T3-7 062399 1210 Total Coliform -- -- 1 -- 

---------------------------------------------------------------------------------------------
APPENDIX 137

samples. No detections were reported from the three 

field-blank samples. One of the two laboratory blanks 

from the April 2001 sampling showed four estimated 

concentrations, but the values were below the method 

reporting level (MRL). The other laboratory blank 

showed two estimated concentrations, both below the 

MRL. The laboratory blank from the September 2001 

sampling showed no concentrations above the MRL. 

Laboratory procedures adjust the MRL upward for 

the environmental samples to account for potential 

contamination documented in the blank samples. In 

general, the compounds detected in blanks do not 

show values above censoring limits in the environmental sample results of the same lot. 

Duplicate Samples

 Duplicate samples are collected to test 

repeatability, and they were prepared by collecting 

two aliquots of water for each analysis. In theory 

the results from each aliquot should be the same; 

deviations describe laboratory precision or problems 

with field techniques. The results of duplicate samples 

from this study were evaluated by computing relative 

percent differences (rpd’s) for different categories that 

were defined on the basis of analytical methodology 

(table A3). The rpd was computed with the following 

equation:

(A5)

where 

C1 is the concentration for aliquot 1, and

C2 is the concentration for aliquot 2.

Table A3 indicates that the highest rpd, 

from –123 to 178, occurred in ICP analyses. An 

arbitrarily defined rpd bracket from –20 to 20 contains 

83.5 percent of ICP analyses. The other analysis categories, especially cations and anions, contain a larger 

percentage of samples in the –20 to 20 rpd bracket. 

These results indicate that confidence in reported 

results is highest for cations and anions and somewhat 

lower for other analyses. 

Tritium results showed good reproducibility in 

laboratory replicates, with mean percent difference at 

about 10 percent. Laboratory standard deviations of 

counting error were generally smaller than plus or minus 

2 tritium units. Field duplicates had a mean rpd of about 

5 percent.

rpd C1 – C2

( ) C1 + C2 ⁄ 2 = -------------------------------- × 100

Table A3. Statistics for relative percent differences in duplicate samples

[Note: Q25, 25th percentile; Q75, 75th percentile; Bracket, percentage of samples 

 greater than -20 and less than 20 relative percent difference; N, number of 

 samples]

----------------------------------------------------------------------------------

 Analysis category Mean Median Q25 Q75 Minimum Maximum Bracket N

----------------------------------------------------------------------------------

Total organic carbon 2.24 0 -5.71 8.33 -53.97 62.07 88.57 35

Nutrients 5.26 0 -0.37 5.36 -128.87 111.11 88.50 87

AAGF metals 3.56 0 -1.45 10.85 -104.00 85.71 84.78 92

ICP metals 1.23 0 -1.50 1.95 -123.57 178.29 83.50 358

Cations -0.95 0 -0.64 0.82 -84.71 28.18 98.50 133

Anions -0.07 0 -0.25 1.26 -181.68 47.51 96.03 151

----------------------------------------------------------------------------------
138 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed,

Jefferson County, Colorado, 1998–2001 Table A4. Selected site characteristics for water levels measured in fall 2001 [USGS id, 15-digit NWIS identifier; Local, local id; Cell, refers to project grid identifier; Permit, well permit number from State Engineers Office; Latitude and Longitude, degrees minutes and seconds determined with commercial Global Positioning units and referenced to North American Datum of 1927; Elev, altitude above mean sea level determined from 1:24,000 topographic maps and referenced to National Geodetic Vertical Datum of 1929; MP, height of measuring point above land surface; Date, month day and year of measurement; Time, hours and minutes of measurement; DTW, measured depth from measuring point to water in well; na, not applicable, unk, unknown] ----------------------------------------------------------------------------------------------------------------------------------------------------------------- USGS id Local Cell Permit Latitude Longitude Elev Measuring point description MP Date Time DTW Status ----------------------------------------------------------------------------------------------------------------------------------------------------------------- 393035105204500 na 4 166346 393034.5 1052045.4 9255 top of casing 0.40 09/27/01 1410 116.48 recently pumped 393039105200700 na 5 198794 393038.8 1052006.5 9030 top of casing 1.00 10/02/01 1445 449.00 recently pumped 393116105210900 na 21 148360 393115.5 1052109.0 9530 top of casing 0.00 09/27/01 1819 148.60 affected by nearby pumping 393101105205100 na 22 169640 393100.5 1052050.5 9460 top of casing 0.50 10/02/01 1600 150.00 recently pumped 393059105195900 na 24 unk 393058.7 1051959.0 8635 land surface 0.00 10/02/01 1345 0.00 recently pumped 393106105193100 na 25 107927 393106.3 1051931.2 8600 plug in top of casing 0.00 10/02/01 1400 19.44 recently pumped 393107105184300 na 26 75757 393106.7 1051843.0 8480 top of casing 1.00 09/24/01 1107 201.11 pumping 393119105183200 na 26 144671 393119.0 1051832.0 8285 top of casing 0.40 09/26/01 1500 69.65 recently pumped 

393139105220000 na 39 105205 393139.2 1052200.0 9330 top of casing 0.00 09/27/01 1409 23.28 recently pumped 393129105213600 na 40 159879 393128.8 1052136.1 9605 top of casing 0.79 09/27/01 1703 56.05 affected by nearby pumping 393116105202400 na 42 78268 393116.1 1052024.4 8810 top of casing 0.20 09/27/01 1245 98.21 recently pumped 393139105141200 GWO09 53 unk 393138.7 1051410.6 8365 top of casing 1.00 09/28/01 1830 287.00 recently pumped 393144105135600 GWO11 54 unk 393143.5 1051357.8 8445 top of casing 1.00 09/28/01 1800 312.00 recently pumped 393203105220400 na 58 176711 393202.5 1052204.1 8960 top of casing 0.89 09/27/01 1628 11.84 affected by nearby pumping 393159105213500 na 59 184392 393159.2 1052135.4 9095 top of casing 1.60 09/27/01 1451 167.30 recently pumped 393153105211400 na 60 114268 393153.1 1052114.4 8950 top of casing 0.92 09/27/01 1536 109.16 recently pumped 393150105194600 na 62 162862 393149.6 1051946.1 8245 top of casing 0.38 09/26/01 1340 215.40 recently pumped 393157105193400 na 63 161441 393156.5 1051933.8 8245 top of casing 0.75 09/26/01 1300 72.75 recently pumped 393206105204800 GWK08 64 unk 393206.4 1052046.0 8445 top of casing 1.00 09/26/01 1210 4.50 recently pumped 393153105180700 na 65 13467 393152.7 1051806.8 8235 top of casing 1.50 09/26/01 1520 48.43 recently pumped 393202105183200 na 65 unk 393202.1 1051832.2 8060 top of casing 1.10 09/25/01 1216 12.00 recently pumped 393204105180200 GWP04 66 unk 393205.0 1051759.5 8275 top of casing 0.75 09/26/01 1550 30.17 recently pumped 393206105141800 GWO07 72 unk 393204.3 1051415.9 7915 top of casing 1.10 09/26/01 1120 128.83 recently pumped 393202105135200 na 73 126079 393201.6 1051351.5 7985 top of casing 0.30 09/26/01 1030 47.56 recently pumped 393240105205600 na 79 unk 393240.2 1052056.1 8660 top of casing 0.82 09/26/01 1416 60.25 affected by nearby pumping 393240105205600 na 79 193063 393239.8 1052056.1 8655 top of casing 0.50 09/26/01 1402 54.70 affected by nearby pumping 393234105201800 GWJ03 80 unk 393233.8 1052016.4 8620 top of casing 1.20 09/26/01 1547 137.50 affected by nearby pumping 393230105201000 GWJ02 81 unk 393229.7 1052008.8 8505 top of casing 0.67 09/26/01 1523 86.82 recently pumped 393216105184100 na 83 173558 393216.1 1051841.1 8230 top of casing 1.30 09/26/01 1140 185.00 recently pumped 393233105181300 na 84 unk 393232.7 1051813.0 8245 top of casing 1.20 10/03/01 1315 100.71 recently pumped 393249105163800 na 86 140549 393248.5 1051638.0 7915 top of casing 1.50 09/27/01 1045 32.03 recently pumped 393237105162900 GWP99 87 unk 393236.8 1051626.2 8150 plug in top of casing 1.80 10/02/01 1840 16.92 pumping 393221105152700 na 89 unk 393221.2 1051527.1 7910 top of casing 0.30 10/02/01 1115 26.70 recently pumped 393238105152000 GWO04 89 unk 393240.0 1051516.9 7790 top of casing 0.90 09/26/01 1405 51.86 recently pumped 393413105135800 GWM04 89 unk 393413.0 1051355.8 7400 top of casing 1.00 09/26/01 1400 24.37 recently pumped 393231105144000 GWO06 91 unk 393230.5 1051438.6 7770 top of casing 1.80 09/26/01 1500 127.55 recently pumped 393226105133100 na 92 unk 393226.0 1051331.0 7805 top of casing -0.20 09/28/01 1430 195.00 recently pumped 393228105133800 na 92 182209 393228.0 1051338.0 8015 top of casing 1.10 09/28/01 1500 332.00 recently pumped 393237105222900 GWK05 96 unk 393136.7 1052227.4 9910 top of casing 0.95 09/27/01 1158 183.50 affected by nearby pumping 393241105214500 na 97 unk 393241.0 1052145.0 8795 top of casing 1.75 09/26/01 1836 64.27 recently pumped 393241105214500 na 97 163824 393241.3 1052145.0 8790 top of casing 1.50 09/26/01 1815 67.29 recently pumped 393243105220000 na 97 131563 393243.4 1052200.1 8870 top of casing 1.00 09/26/01 1924 159.04 recently pumped 393245105210100 na 98 63571 393244.9 1052101.4 8665 top of casing 0.67 09/26/01 1738 73.74 recently pumped 393242105202000 GWI01 99 unk 393241.2 1052018.8 8560 top of casing 0.69 09/26/01 1715 101.66 affected by nearby pumping 
APPENDIX 139

Table A4. Selected site characteristics for water levels measured in fall 2001—Continued[USGS id, 15-digit NWIS identifier; Local, local id; Cell, refers to project grid identifier; Permit, well permit number from State Engineers Office; Latitude  and Longitude, degrees minutes and seconds determined with commercial Global Positioning units and referenced to North American Datum of 1927; Elev, altitude  above mean sea level determined from 1:24,000 topographic maps and referenced to National Geodetic Vertical Datum of 1929; MP, height of measuring point above  land surface; Date, month day and year of measurement; Time, hours and minutes of measurement; DTW, measured depth from measuring point to water in well; na,  not applicable, unk, unknown]-----------------------------------------------------------------------------------------------------------------------------------------------------------------USGS id Local Cell Permit Latitude Longitude Elev Measuring point description MP Date Time DTW Status -----------------------------------------------------------------------------------------------------------------------------------------------------------------393417105192800 na 99 unk 393416.8 1051928.0 8035 top of casing 1.50 09/25/01 1710 55.24 recently pumped 393300105194400 GWI04 100 unk 393300.1 1051941.2 8075 top of casing 1.25 09/25/01 1840 40.35 recently pumped 393303105191700 na 101 160087 393302.8 1051916.8 8230 top of casing 0.00 09/26/01 1748 324.00 recently pumped 393259105185700 GWJ07 102 unk 393301.6 1051855.0 7910 top of casing 0.65 09/25/01 1040 14.40 recently pumped 393244105172600 GWP05 105 unk 393243.3 1051723.5 8175 plug in top of casing -6.00 09/26/01 1040 78.15 recently pumped 393245105170000 na 106 156090 393244.9 1051700.4 8030 top of casing 0.70 09/25/01 1335 14.96 recently pumped 393250105155100 na 107 71984 393250.1 1051550.6 7850 top of casing 1.00 09/25/01 1230 62.28 recently pumped 393301105153100 MH8 108 unk 393301.2 1051529.9 8095 top of casing 1.00 09/26/01 1230 14.64 static 393245105145000 GWO05 109 unk 393245.6 1051447.8 7900 top of casing 2.20 09/26/01 1300 55.45 recently pumped 393316105192400 na 120 137486 393315.9 1051923.8 8105 top of casing 0.00 09/25/01 1710 161.80 recently pumped 393308105184900 GWJ09 121 unk 393308.5 1051846.5 7970 top of casing 0.75 09/25/01 1400 85.65 recently pumped 393316105182400 na 122 unk 393316.1 1051823.8 8045 top of casing 0.50 10/02/01 1245 26.96 recently pumped 393320105184000 na 122 unk 393319.7 1051840.0 8030 top of casing 0.10 09/25/01 1700 109.65 recently pumped 393318105170400 na 124 130385 393318.2 1051703.8 8290 top of casing 0.70 09/25/01 1407 82.17 recently pumped 393322105165000 na 125 96541 393322.0 1051649.9 8250 top of casing 0.80 10/02/01 1155 42.38 recently pumped 393306105161300 na 126 163851 393306.4 1051613.1 8330 top of casing 1.10 09/25/01 1525 188.39 recently pumped 393324105152300 na 127 152613 393323.7 1051523.2 8210 top of casing 0.70 09/26/01 1030 56.46 recently pumped 393308105145500 GWN01 128 unk 393307.7 1051453.4 7910 top of casing 0.90 09/26/01 1345 137.23 pumping 393308105132100 na 131 unk 393307.6 1051321.4 7335 top of casing 0.60 10/02/01 940 26.44 recently pumped 393334105192500 GWI03 139 unk 393333.9 1051923.2 7915 top of casing 1.10 09/25/01 1817 35.90 pumping 393350105184300 MH5 140 unk 393351.3 1051851.8 7815 plug in top of casing 1.00 09/25/01 1135 33.00 static 393347105180300 na 141 99212 393346.5 1051803.1 8350 top of casing 0.30 09/25/01 1625 109.90 recently pumped 393344105171400 MH6.2 143 unk 393344.3 1051714.2 8352 top of casing -- aribtrary 1.00 10/03/01 955 11.07 static 393344105155100 na 145 75392 393344.0 1051550.5 8645 top of casing 0.80 09/28/01 1200 201.50 recently pumped 393334105153600 na 146 155910 393333.8 1051536.1 8445 top of casing 1.50 09/26/01 1125 189.75 recently pumped 393332105150800 MH7 147 unk 393331.6 1051505.1 8310 top of casing 1.10 09/27/01 1540 61.12 static 393411105193400 na 158 83100 393411.0 1051934.4 8045 top of casing 0.65 09/25/01 1624 69.55 recently pumped 393417105183800 na 159 unk 393417.0 1051838.0 7755 top of casing 1.50 09/27/01 1430 7.23 recently pumped 393404105182200 GWG02 160 unk 393403.6 1051819.5 7930 top of casing 1.50 09/25/01 1224 168.40 recently pumped 393401105152000 na 165 192690 393400.7 1051519.5 8230 top of casing -0.40 09/28/01 1000 84.80 recently pumped 393405105151400 na 166 185829 393404.8 1051513.8 7985 top of casing 0.75 09/28/01 920 141.70 recently pumped 393413105132200 GWM03 169 unk 393413.6 1051319.8 7185 top of casing 0.80 09/25/01 1340 11.70 recently pumped 393401105124600 GWM07 170 unk 393419.0 1051250.8 7265 top of casing 0.90 09/25/01 1000 128.60 pumping 393442105193900 na 177 67402 393442.4 1051938.8 8130 top of casing 0.69 09/25/01 1500 156.95 recently pumped 393432105180300 na 180 92639 393431.6 1051802.8 8055 top of casing 1.00 09/25/01 1520 190.50 recently pumped 393448105170100 GWH01 181 unk 393446.8 1051657.4 7685 top of casing 0.30 09/25/01 1025 103.35 recently pumped 393444105165500 GWH03 182 unk 393443.8 1051653.2 7670 top of casing 0.70 09/24/01 1425 45.22 recently pumped 393437105160700 GWF13 183 unk 393437.4 1051605.5 7890 top of casing 0.25 09/28/01 1105 76.80 recently pumped 393429105154700 na 184 155281 393429.1 1051546.8 7885 top of casing 0.50 09/28/01 1205 12.72 recently pumped 393424105134800 GWM05 187 unk 393424.0 1051346.0 7405 top of casing 1.90 09/28/01 1100 83.40 recently pumped 393437105183900 na 188 100105 393436.5 1051838.6 7720 top of casing 0.90 09/25/01 1315 10.15 recently pumped 393447105132700 na 188 187827 393446.5 1051327.1 7350 top of casing 0.60 09/25/01 1125 101.30 recently pumped 393426105130000 GWM09 189 unk 393424.8 1051258.5 7045 top of casing 1.00 09/25/01 1235 5.30 recently pumped 393504105183200 na 198 19859 393503.7 1051832.2 7775 plug in top of casing -0.10 09/25/01 1810 33.15 recently pumped 393503105174400 na 199 88930 393503.1 1051744.1 7855 top of casing 0.90 09/25/01 1110 76.05 recently pumped 
140 Hydrologic Conditions and Assessment of Water Resources in the Turkey Creek Watershed,

Jefferson County, Colorado, 1998–2001 Table A4. Selected site characteristics for water levels measured in fall 2001—Continued [USGS id, 15-digit NWIS identifier; Local, local id; Cell, refers to project grid identifier; Permit, well permit number from State Engineers Office; Latitude and Longitude, degrees minutes and seconds determined with commercial Global Positioning units and referenced to North American Datum of 1927; Elev, altitude above mean sea level determined from 1:24,000 topographic maps and referenced to National Geodetic Vertical Datum of 1929; MP, height of measuring point above land surface; Date, month day and year of measurement; Time, hours and minutes of measurement; DTW, measured depth from measuring point to water in well; na, not applicable, unk, unknown] ------------------------------------------------------------------------------------------------------------------------------------------------------------- USGS id Local Cell Permit Latitude Longitude Elev Measuring point description MP Date Time DTW Status ------------------------------------------------------------------------------------------------------------------------------------------------------------- 393459105165701 MH4 200 unk 393459.6 1051655.5 7685 top of casing 0.10 09/24/01 1527 100.56 static 393452105151900 na 203 141447 393451.8 1051518.6 7470 top of casing 1.67 09/27/01 1150 91.82 recently pumped 393531105172700 na 219 51645 393530.5 1051727.2 8150 top of casing 1.00 09/27/01 1030 148.88 recently pumped 393532105150500 GWF02 223 unk 393531.6 1051503.2 7435 top of casing 1.00 09/28/01 1250 30.50 recently pumped 393536105140800 na 224 53567 393536.0 1051408.0 7250 top of casing 0.40 09/27/01 1130 22.34 recently pumped 393522105133800 na 225 53567 393522.0 1051338.0 7330 top of casing 0.30 09/27/01 1800 174.25 recently pumped 

393552105172900 na 237 78185 393552.0 1051728.6 7990 top of casing 0.50 09/27/01 1300 162.25 recently pumped 393557105170200 na 238 117459 393557.1 1051701.8 7975 top of casing 0.25 09/27/01 1330 290.30 recently pumped 393547105165100 na 239 79269 393546.9 1051650.8 7725 top of casing 0.58 09/27/01 1430 76.98 recently pumped 393547105151500 na 241 73879 393546.5 1051515.2 7500 top of plate 0.50 09/28/01 1350 66.53 recently pumped 393547105144900 na 242 83170 393546.5 1051449.2 7400 top of casing 1.50 10/01/01 1125 75.52 recently pumped 393552105143600 GWF09 243 unk 393551.5 1051434.1 7420 top of casing 0.30 10/01/01 1045 49.42 recently pumped 393551105140100 na 244 104479 393551.0 1051401.0 7370 top of casing 0.40 09/27/01 1330 350.00 recently pumped 393604105132200 GWB02 245 unk 393604.3 1051320.6 6840 top of casing 0.25 09/24/01 1105 34.98 recently pumped 393543105123700 na 246 152277 393543.0 1051237.2 7285 top of casing 0.75 09/24/01 1140 54.19 recently pumped 393616105165000 na 258 131231 393615.6 1051650.4 7810 top of casing 1.00 09/27/01 1650 94.55 recently pumped 393625105161400 na 259 159923 393625.0 1051614.0 7965 top of casing 1.00 09/27/01 1100 228.00 recently pumped 393609105152300 na 260 131580 393608.5 1051523.1 7635 top of casing 0.50 09/28/01 1430 na .00 recently pumped 393614105152000 na 261 37790 393613.5 1051520.0 7670 top of casing 1.30 09/27/01 1030 100.90 recently pumped 393643105165600 na 276 175105 393642.8 1051656.2 7895 top of casing 0.60 10/01/01 1400 101.49 recently pumped 393640105164400 GWF15 277 unk 393643.1 1051640.5 7895 top of casing 1.50 09/25/01 1745 24.93 pumping 393643105163600 na 277 unk 393643.4 1051635.8 7895 top of casing 0.70 09/25/01 1824 50.63 recently pumped 393634105154500 na 278 197500 393634.0 1051545.0 7865 top of casing 0.30 09/27/01 1700 204.00 recently pumped 393637105134300 na 282 198923 393637.3 1051342.5 6900 top of casing 0.95 09/27/01 1042 401.80 recently pumped 393710105164900 na 296 89582 393709.7 1051649.4 8170 top of casing 0.20 09/25/01 1900 168.55 recently pumped 393710105165000 na 296 unk 393709.5 1051650.2 8175 top of casing 0.80 09/25/01 1920 158.81 recently pumped 393713105155300 na 298 197797 393713.2 1051553.0 7525 top of casing 0.70 09/24/01 1720 105.09 recently pumped 393721105153100 na 298 189222 393720.8 1051530.6 7475 top of casing 0.00 10/02/01 1030 287.00 recently pumped 393711105145200 na 299 226879 393710.5 1051452.4 7095 top of casing 0.70 09/28/01 1000 66.68 affected by nearby pumping 393723105135800 na 301 118865 393723.1 1051358.2 7300 top of casing 0.00 09/28/01 1132 375.00 pumping 393712105131100 na 302 unk 393711.9 1051310.6 6605 top of casing 0.88 09/24/01 1314 58.80 recently pumped 393738105171000 na 314 54005 393738.4 1051709.8 8410 top of casing 0.20 10/02/01 1300 368.00 recently pumped 393727105164900 na 315 100062 393726.9 1051648.5 8205 top of casing 0.40 10/01/01 1500 125.84 recently pumped 393745105160100 na 316 111412 393745.3 1051601.1 7435 top of casing -0.40 09/24/01 1420 91.58 recently pumped 393728105151700 na 317 5681433 393728.0 1051517.0 7135 ticg 0.70 09/27/01 1900 7.00 recently pumped 393734105151300 na 318 190413 393733.6 1051512.5 7090 top of casing 0.60 09/24/01 1800 20.49 recently pumped 393753105155300 na 335 97142 393753.2 1051553.0 7325 top of casing 0.20 09/24/01 1500 53.04 affected by nearby pumping 393756105154400 na 336 unk 393756.4 1051544.4 7275 top of casing 1.50 09/24/01 1655 40.43 recently pumped 393125105220900 na na 217016 393124.7 1052208.5 9790 top of casing 0.95 09/27/01 1323 113.80 affected by nearby pumping 393228105205900 na na 202663 393228.4 1052058.9 8955 top of casing 0.64 09/26/01 1236 329.40 affected by nearby pumping 393359105141100 na na unk 393358.5 1051411.4 7490 top of casing 0.40 10/04/01 1245 17.79 recently pumped 393403105142300 na na unk 393402.5 1051423.2 7445 top of casing 0.40 10/04/01 1245 15.06 recently pumped -------------------------------------------------------------------------------------------------------------------------------------------------------------