U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2007–5104

Prepared in cooperation with Colorado Springs City Engineering

Characterization of Stormflows and Wastewater 

Treatment-Plant Effluent Discharges on Water Quality, 

Suspended Sediment, and Stream Morphology for Fountain 

and Monument Creek Watersheds, Colorado, 1981–2006
Cover photograph: Monument Creek, Colorado, by Robert W. Stogner, Sr.
Characterization of Stormflows and 

Wastewater Treatment-Plant Effluent 

Discharges on Water Quality, Suspended 

Sediment, and Stream Morphology 

for Fountain and Monument Creek 

Watersheds, Colorado, 1981–2006

By David P. Mau, Robert W. Stogner, Sr., and Patrick Edelmann

Prepared in cooperation with Colorado Springs City Engineering

Scientific Investigations Report 2007–5104

U.S. Department of the Interior

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

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2007

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Suggested citation:

Mau, D.P., Stogner, R.W., Sr., and Edelmann, Patrick, 2007, Characterization of stormflows and wastewater treatmentplant effluent discharges on water quality, suspended sediment, and stream morphology for Fountain and Monument 

Creek watersheds, Colorado, 1981–2006: U.S. Geological Survey Scientific Investigations Report 2007–5104, 76 p.
iii

Contents

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

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

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

Description of Study Area ...................................................................................................................6

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

Acknowledgments..............................................................................................................................12

Methods of Investigation............................................................................................................................12

Flow Regime.........................................................................................................................................12

Water-Quality Data.............................................................................................................................12

Suspended-Sediment Data ...............................................................................................................13

Boxplots................................................................................................................................................13

Statistical Analyses............................................................................................................................13

Precipitation and Streamflow....................................................................................................................14

Water Quality................................................................................................................................................17

Relation of Water Quality to Land Use ............................................................................................17

Comparison of Stormflow Water Quality to Colorado In-Stream Water-Quality 

Standards................................................................................................................................17

Onsite Measurements of Specific Conductance, pH, and Dissolved Oxygen..........................19

Specific Conductance...............................................................................................................19

pH and Dissolved Oxygen.........................................................................................................19

Biochemical Oxygen Demand ..........................................................................................................19

Biochemical Oxygen Demand Concentrations during 1998 through 2006 .......................19

Comparison of Biochemical Oxygen Demand Concentrations between 1981 

through 1997 and 1998 through 2006 .........................................................................22

Bacteria................................................................................................................................................22

Fecal Coliform Bacteria during 1998 through 2006...............................................................22

Comparison of Fecal Coliform Concentrations between 1981 through 1997 

and 1998 through 2006 .................................................................................................25

Escherichia Coli (E. coli) Bacteria Concentrations ..............................................................25

Escherichia Coli (E. coli) Bacteria Concentrations at Tributary Sites...............................25

Nitrogen and Phosphorus .................................................................................................................25

Dissolved Nitrite plus Nitrate...................................................................................................25

Total Phosphorus .......................................................................................................................29

Effect of Wastewater Treatment Plants.................................................................................29

Comparisons of Nitrogen and Phosphorus Concentrations between 1981 

through 1997 and 1998 through 2006 .........................................................................29

Trace Elements....................................................................................................................................29

Main-Stem Trace-Element Concentrations from 1998 through 2006.................................33

Sand Creek Trace-Element Concentrations from 2003 through 2006................................33

Comparisons of Trace-Element Concentrations between 1981 through 

1997 and 1998 through 2006 ........................................................................................34

Comparison of Loads during Stormflow and Base-Flow and Normal-Flow Conditions..........34

Nitrogen and Phosphorus Loads.............................................................................................34
iv

Main-Stem Nitrogen and Phosphorus Loads...............................................................34

Tributary Nitrogen and Phosphorus Loads...................................................................34

Trace-Element Loads.................................................................................................................39

Trace-Element Loads in Upper Fountain Creek ...........................................................39

Trace-Element Loads in Monument Creek Upstream from Confluence..................39

Trace-Element Loads in Fountain Creek Downstream from Confluence.................39

Suspended Sediment ..................................................................................................................................39

Spatial Variations in Suspended-Sediment Concentrations .......................................................42

Base Flow....................................................................................................................................42

Normal Flow................................................................................................................................42

Stormflow....................................................................................................................................42

Spatial Variations in Suspended-Sediment Discharges ..............................................................45

Base Flow....................................................................................................................................45

Normal Flow................................................................................................................................45

Stormflow....................................................................................................................................47

Cumulative Suspended-Sediment Discharge .......................................................................47

Spatial Variations in Suspended-Sediment Yields ........................................................................47

Base Flow....................................................................................................................................47

Normal Flow and Stormflow ....................................................................................................52

Variations in Instantaneous Streamflow, Suspended-Sediment Concentration, 

Suspended-Sediment Discharge, and Suspended-Sediment Yield at 

Selected Tributaries in the Fountain and Monument Creek Watersheds....................52

Suspended-Sediment Concentrations at Selected Tributaries in the Fountain 

and Monument Creek Watersheds during Normal Flow and Stormflow............52

Suspended-Sediment Discharges at Selected Tributaries in the Fountain and 

Monument Creek Watersheds during Normal Flow and Stormflow....................53

Suspended-Sediment Yields at Selected Tributaries in the Fountain and 

Monument Creek Watersheds during Normal Flow and Stormflow....................53

Stream Morphology.....................................................................................................................................53

Sediment-Transport Capacity ...........................................................................................................57

Descriptive Assessment of Changes in Channel Morphology....................................................57

Cottonwood Creek .....................................................................................................................61

Monument Creek .......................................................................................................................65

Fountain Creek............................................................................................................................66

Sand Creek..................................................................................................................................70

Summary........................................................................................................................................................70

References Cited..........................................................................................................................................73
Figures

1. Map showing location of study area and sampling sites for the Fountain and 

Monument Creek watersheds ....................................................................................................3

2. Graphs showing annual precipitation at the Colorado Springs Weather Service 

Office, (A) 1949 through 2006, and (B) 1981 through 2006 ....................................................15

3–20. Boxplots showing:

3. Variations in sampled streamflow at (A) main-stem sites, and (B) tributary 

sites for base flow, normal flow, and stormflow in Fountain and Monument 

Creek watersheds, 1998 through 2006, and (C) comparison of sampled 

streamflow at selected main-stem sites between 1981 through 1997 and 

1998 through 2006 ..............................................................................................................16

4. Variations in specific conductance at (A) main-stem sites and (B) tributary 

sites for base flow, normal flow, and stormflow in Fountain and Monument 

Creek watersheds, 1998 through 2006............................................................................20

5. Variations in (A) pH, (B) dissolved oxygen concentrations, and (C) percent 

saturation of dissolved oxygen at main-stem sites and Sand Creek for base 

flow, normal flow, and stormflow in Fountain and Monument Creek 

watersheds, 1998 through 2006 .......................................................................................21

6. Variations in 5-day biochemical oxygen demand (BOD5) for base flow, 

normal flow, and stormflow at (A) main-stem sites in Fountain and 

Monument Creek watersheds, 1998 through 2006, (B) a comparison of 

BOD5 concentrations between 1981 through 1997 and 1998 through 2006, 

and (C) temporal variations in 5-day biochemical oxygen demand (BOD5) 

at site 07105530 ..................................................................................................................23

7. Variations in fecal coliform for base flow, normal flow, and stormflow at 

(A) main-stem sites, (B) tributary sites in Fountain and Monument Creek 

watersheds, 1998 through 2006, and (C) comparison of variations in 

fecal coliform between 1981 through 1997 and 1998 through 2006 ...........................24

8. Variations in Escherichia coli (E. coli) for base flow, normal flow, and 

stormflow at (A) main-stem sites, and (B) tributary sites in Fountain and 

Monument Creek watersheds, 1998 through 2006 .......................................................26

9. Variations in nitrogen and phosphorus concentrations at main-stem sites 

for base flow, normal flow, and stormflow in the Fountain and Monument 

Creek watersheds, 1998 through 2006............................................................................27

10. Variations in nitrogen and phosphorus concentrations at tributary sites 

for base flow, normal flow, and stormflow in the Fountain and Monument 

Creek watersheds, 1998 through 2006............................................................................28

11. Variations in nitrite plus nitrate, ammonia, and phosphorus concentrations 

at selected sites between 1981 through 1997 and 1998 through 2006 for base 

flow, normal flow, and stormflow in the Fountain and Monument Creek 

watersheds .........................................................................................................................30

12. Variations in arsenic, boron, copper, lead, and manganese at main-stem 

sites for base flow, normal flow, and stormflow in the Fountain and 

Monument Creek watersheds, 1998 through 2006 .......................................................31

13. Variations in nickel, selenium and zinc at main-stem sites for base flow, 

normal flow, and stormflow in the Fountain and Monument Creek 

watersheds, 1998 through 2006 .......................................................................................32
vi

14. Variations in boron, copper, lead, and manganese concentrations 

between 1981 through 1997 and 1998 through 2006 at selected sites for 

base flow, normal flow, and stormflow in the Fountain and Monument 

Creek watersheds..............................................................................................................35

15. Variations in nickel, selenium, and zinc concentrations between 1981 

through 1997 and 1998 through 2006 at selected main-stem sites for 

base flow, normal flow, and stormflow in the Fountain and Monument 

Creek watersheds..............................................................................................................36

16. Variations in nitrogen and phosphorus loads at main-stem sites for 

base flow, normal flow, and stormflow in the Fountain and Monument 

Creek watersheds, 1998 through 2006............................................................................37

17. Variations in nitrogen and phosphorus loads at tributary sites for 

base flow, normal flow, and stormflow in the Fountain and 

Monument Creek watersheds, 1998 through 2006 .......................................................38

18. Variations in streamflow, arsenic, boron, copper, and lead loads at 

main-stem sites for base flow, normal flow, and stormflow in the 

Fountain and Monument Creek watersheds, 1998 through 2006...............................40

19. Variations in manganese, nickel, selenium, and zinc loads at main-stem 

sites for base flow, normal flow, and stormflow in the Fountain and 

Monument Creek watersheds, 1998 through 2006 .......................................................41

20. Variations in (A) suspended-sediment concentration, (B) suspendedsediment discharge, and (C) suspended-sediment yield for base flow, 

normal flow, and stormflow at selected main-stem and tributary sites 

in Fountain and Monument Creek watersheds,............................................................43

21–25. Maps showing:

21. Cumulative suspended-sediment discharge in the Fountain and 

Monument Creek watersheds, 1998 through 2001 .......................................................48

22. Cumulative suspended-sediment discharge in the Fountain and 

Monument Creek watersheds, 2002 through 2005 .......................................................49

23. Variations in suspended-sediment concentration during normal flow 

and stormflow at selected tributaries in the Fountain and Monument 

Creek watersheds..............................................................................................................54

24. Variations in suspended-sediment discharge during normal flow and 

stormflow at selected tributaries in the Fountain and Monument Creek 

watersheds .........................................................................................................................55

25. Variations in suspended-sediment yield during normal flow and stormflow 

at selected tributaries in Fountain and Monument Creek watersheds ....................56

26. Computation of cross-section sediment area and reach sediment volume.....................60

27–33. Graphs showing:

27. Change in minimum streambed altitude at cross sections along selected 

reaches of Cottonwood Creek near sites 07103977 (upper_CoCr), 07103980 

(middle_CoCr), 07103985 (TbCo), and 07103990 (lower_CoCr), October 1999 

through October 2005........................................................................................................62

28. Cumulative change in volume of sediments of selected reaches of 

Cottonwood Creek near sites 07103977 (upper_CoCr), 07103980 

(middle_CoCr), 07103985 (TbCo), and 07103990 (lower_CoCr), 

1999 through 2005 ..............................................................................................................65

29. Change in minimum streambed altitude at cross sections along a reach 

of Monument Creek near site 07103970 (MoCr_Woodmen), October 2000 

through October 2005........................................................................................................67
vii

30. Cumulative change in volume of sediments of a reach of Monument 

Creek near site 07103970 (MoCr_Woodmen), 2000 through 2005..............................67

31. Change in minimum streambed altitude at cross sections along selected 

reaches of Fountain Creek near sites 07103700 (FoCr_Manitou) and 

07105800 (FoCr_Security), October 1999 through October 2005 ................................68

32. Cumulative change in volume of sediments of selected reaches of 

Fountain Creek near site 07103700 (FoCr_Manitou) and 07105800 

(FoCr_Security), 1999 through 2005 ................................................................................69

33. Change in minimum streambed altitude at cross sections along a reach of 

Sand Creek near site 07105600 (SaCr), October 2003 through October 2005...........71

Tables

1. Selected surface-water sites in the Fountain and Monument Creek watersheds, 

and biological properties, water-quality constituents and suspended sediment 

measured or analyzed, and channel geometry surveys, 1981 through 2006 ......................4

2. Land uses and estimated total impervious area for the Fountain and Monument 

Creek watersheds in El Paso County, Colorado, 1997, 2001, and 2005.................................7

3. Imperviousness coefficients for land-use categories and subcategories in the 

Fountain and Monument Creek watersheds. ........................................................................10

4. Correlations between various land uses and physical properties and selected 

water-quality constituents for sites in the Fountain and Monument Creek 

watersheds, 1998 through 2005 ................................................................................................18

5. Median suspended-sediment concentration during base flow, normal flow, 

and stormflow in the Fountain and Monument Creek watersheds, and p-values of 

Mann-Whitney test of significance of spatial variations in suspended-sediment 

concentrations ............................................................................................................................44

6. Median suspended-sediment discharge during base flow, normal flow, and 

stormflow in the Fountain and Monument Creek watersheds, and p-values of 

Mann-Whitney test of significance of spatial variations in suspended-sediment 

discharge .....................................................................................................................................46

7. Cumulative suspended-sediment discharge in the Fountain and Monument Creek 

watersheds, annually between April 1 and September 30, 1998, through 2005 ...............50

8. Median suspended-sediment yield during base flow, normal flow, and stormflow 

in the Fountain and Monument Creek watersheds, and p-values of MannWhitney test of significance of spatial variations in suspended-sediment yields ..........51

9. Particle-size distribution for bed material at sites in the Fountain and Monument 

Creek watersheds based on pebble counts measured between 1998 and 2005 .............58

10. Range in particle size of bed material, in millimeters, at threshold of movement 

for upper and lower limits of transport of coarse materials based on minimum 

and maximum measured streamflow in the Fountain and Monument Creek 

watersheds ..................................................................................................................................59

11. Change in minimum bed altitude, cross-section sediment area, and estimated 

mass of sediment eroded or deposited at selected cross sections in the Fountain 

and Monument Creek watersheds, 1999 through 2005 ........................................................63

12. Estimated mass of sediment eroded or deposited from selected reaches of 

Fountain, Monument, Cottonwood, and Sand Creeks, 1999 through 2005 ........................66
viii

Conversion Factors and Datums

Inch/Pound to SI

Multiply By To obtain

Length

inch 2.54 centimeter (cm)

inch 25.4 millimeter (mm)

foot (ft) .3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 4,047 square meter (m2)

square foot (ft2) 929.0 square centimeter (cm2)

square foot (ft2) .09290 square meter (m2)

square mile (mi2) 2.590 square kilometer (km2)

Volume

cubic foot (ft3) 0.02832 cubic meter (m3)

Flow rate

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

Mass

pound, avoirdupois (lb) 0.4536 kilogram (kg) 

ton per day (ton/d) .9072 metric ton per day

ton per year (ton/yr) .9072 metric ton per year

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

°F=(1.8 ×°C)+32

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

°C=(°F–32)/1.8

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

(NAVD 88).”

Horizontal coordinate information is referenced to the “North American Datum of 1983 (NAD 

83).”

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

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).
ix

Abbreviations and initialisms used in this report:

ft3/s cubic feet per second

mg/L milligrams per liter

μg/L micrograms per liter

col/100 mL colonies per 100 milliliters

μS/cm microsiemens per centimeter at 25 degrees Celsius

mm millimeter

mL milliliter

ft feet

ft2 square foot

ft3 cubic foot

lb/ft3 pounds per cubic foot

mi2 square mile

tons/d tons per day

tons/d/mi2 tons per day per square mile

Initialisms used in this report:

CDPHE Colorado Department of Public Health and Environment

CSE Colorado Springs Engineering

CSU Colorado Springs Utilities

GIS Geographic Information System

NWIS National Water Information System

NWQL U.S. Geological Survey National Water Quality Laboratory

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey

VCUP Colorado Voluntary Cleanup Program

WSO Colorado Springs Weather Service Office
Characterization of Stormflows and Wastewater 

Treatment-Plant Effluent Discharges on Water Quality, 

Suspended Sediment, and Stream Morphology for 

Fountain and Monument Creek Watersheds, Colorado, 

1981–2006

By David P. Mau, Robert W. Stogner, Sr., and Patrick Edelmann

normal-flow conditions, the median concentrations of 

dissolved nitrite plus nitrate ranged from 5.1 to 6.1 mg/L 

and were 4 to 7 times larger than concentrations at the 

nearest upstream site on Monument Creek, site 07103970 

(MoCr_Woodmen). The source of these larger dissolved 

nitrite plus nitrate concentrations has not been identified, but 

the fact that all measurements had elevated dissolved nitrite 

plus nitrate concentrations indicates a relatively constant 

source. Most stormflow concentrations of dissolved trace 

elements were smaller than concentrations from base-flow 

or normal-flow samples. However, median concentrations 

of total arsenic, copper, lead, manganese, nickel, and zinc 

generally were much larger during periods of stormflow than 

during base flow or normal flow. Concentrations of dissolved 

and total copper, total manganese, total nickel, dissolved 

and total selenium, and dissolved and total zinc ranged 

from 3 to 27 times larger at site 07103707 (FoCr_8th) than 

site 07103700 (FoCr_Manitou) during base flow, indicating a 

large source of trace elements between these two sites. Both 

of these sites are located on Fountain Creek, upstream from 

the confluence with Monument Creek. The likely source area 

is Gold Hill Mesa, a former tailings pile for a gold refinery 

located just upstream from the confluence with Monument 

Creek, and upstream from site 07103707 (FoCr_8th). Farther 

downstream in Fountain Creek, stormflow samples for total 

copper, manganese, lead, nickel, and zinc were larger at the 

downstream site near the city of Security, site 07105800 

(FoCr_Security), than at the upstream site near Janitell Road, 

site 07105530 (FoCr_Janitell), compared with other mainstem sites and indicated a relatively large source of these 

metals between the two sites. Nitrogen, phosphorus, and traceelement loads substantially increased during stormflow.

Suspended-sediment concentrations, discharges, and 

yields associated with stormflow were significantly larger than 

those associated with normal flow. The April through October 

cumulative suspended-sediment discharges and streamflows 

were largest in 1999 and smallest in 2002. Although large 

Abstract

In 1998, the U.S. Geological Survey, in cooperation 

with Colorado Springs City Engineering, began a study of the 

Fountain and Monument Creek watersheds to characterize 

water quality and suspended-sediment conditions in the 

watershed for different flow regimes, with an emphasis on 

characterizing water quality during storm runoff. Waterquality and suspended-sediment samples were collected in the 

Fountain and Monument Creek watersheds from 1981 through 

2006 to evaluate the effects of stormflows and wastewatertreatment effluent on Fountain and Monument Creeks in the 

Colorado Springs, Colorado, area. Water-quality data were 

collected at 11 sites between 1981 and 2001, and 14 tributary 

sites were added in 2003 to increase spatial coverage and 

characterize water quality throughout the watersheds. 

Suspended-sediment samples collected daily at 7 sites from 

1998 through 2001, 6 sites daily from 2003 through 2006, 

and 13 tributary sites intermittently from 2003 through 2006 

were used to evaluate the effects of stormflow on suspendedsediment concentrations, discharges, and yields. Data were 

separated into three flow regimes: base flow, normal flow, and 

stormflow.

Stormflow concentrations from 1998 through 2006 were 

compared to Colorado acute instream standards and, with the 

exception of a few isolated cases, did not exceed water-quality 

standards for inorganic constituents that were analyzed. 

However, stormflow concentrations of both fecal coliform 

and Escherichia coli (E. coli) frequently exceeded waterquality standards during 1998 through 2006 on main-stem 

and tributary sites by more than an order of magnitude. 

There were two sites on Cottonwood Creek, a tributary to 

Monument Creek, with elevated concentrations of dissolved 

nitrite plus nitrate: site 07103985 (TbCr), a tributary to 

Cottonwood Creek and site 07103990 (lower_CoCr), 

downstream from site 07103985 (TbCr), and near the 

confluence with Monument Creek. During base-flow and 
spatial variations in suspended-sediment yields occurred 

during normal flows, the suspended-sediment yields associated 

with stormflow generally were more than 10 times larger than 

the suspended-sediment yields that occurred during normal 

flow. The largest suspended-sediment yields occurred at sites 

on streams located in the Colorado Piedmont that drain to 

Fountain and Monument Creeks from the east.

Minimum streamflows at all sites have the capacity to 

transport coarse sand and gravel, and maximum streamflows 

at some sites have the capacity to transport coarse gravel to 

cobble-size material. Channel downcutting is the predominant 

channel-forming process. Wastewater treatment-plant 

discharge increased streamflow and transport capacity, 

resulting in a shift in median bed-material size from fine to 

medium gravel.

Introduction

Fountain Creek is a tributary of the Arkansas River, 

draining a 926-mi2 area that includes portions of El Paso, 

Teller, and Pueblo Counties. Monument Creek is a major 

tributary to Fountain Creek, draining 235 mi2. The population 

of the metropolitan areas in and around Colorado Springs 

within the Fountain Creek watershed has increased rapidly 

between 1950 and 2006. Accompanying the increase in 

population in the Fountain Creek watershed have been 

considerable changes in land use and water use. In addition, 

the volume of treated municipal waste return flows discharged 

to Fountain and Monument Creeks has increased with 

population. Information is needed on water quality and stream 

morphology of Fountain and Monument Creeks to evaluate 

stream health and changes with time related to population 

increase within the watersheds. In addition, the information 

can be used to satisfy water-quality permit requirements for 

the City of Colorado Springs (City of Colorado Springs, 

1997).

In 1998, the U.S. Geological Survey, in cooperation 

with Colorado Springs City Engineering, began a study of 

the Fountain and Monument Creek watersheds (fig. 1) to 

characterize water quality and suspended-sediment conditions 

in the watershed for different flow regimes, with an emphasis 

on characterizing water quality during storm runoff. The 

scope of the study also included evaluating changes in water 

quality, suspended sediment, and channel morphology and 

to the extent possible, evaluated the effects of wastewater 

treatment-plant operations on water quality and suspended 

sediment. Historical (pre-1998) water-quality data and 

channel-morphology data form a baseline for comparison 

to data collected during the post-1997 period (1998–2006). 

These two periods were selected to allow comparison of the 

pre-permit period (1981 through 1997) to the years that have 

had water-quality permit requirements (1998 through 2006) 

(City of Colorado Springs, 1997). The year 1981 was chosen 

because laboratory analytical methods changed in 1980 for 

many water-quality constituents and data prior to that year 

would be incomparable to post-1981 data.

Purpose and Scope

This report describes a characterization of stormflows 

and wastewater treatment-plant effluent discharges on water 

quality, suspended sediment, and stream morphology of 

Fountain and Monument Creek watersheds. More specifically 

the report (1) provides a comparison of water-quality 

concentrations for base flow, normal flow, and stormflow; 

(2) compares water quality of stormflow for 1981 through 

1997 and 1998 through 2006; (3) compares water-quality 

concentrations of stormflow to Colorado acute instream 

water-quality standards; (4) characterizes water-quality loads 

for base flow, normal flow, and stormflow; (5) evaluates 

suspended-sediment concentrations and loads for base flow, 

normal flow, and stormflow; (6) describes the sediment 

transport capacity of selected reaches of Fountain, Monument, 

Cottonwood, and Sand Creeks; and (7) describes changes 

in morphology of selected reaches and cross sections of 

Fountain, Monument, Cottonwood, and Sand Creeks.

Water-quality samples were collected from seven mainstem sites: five on Fountain Creek and two on Monument 

Creek (table 1). Water-quality samples were classified 

into two groups: routine and storm. Routine water-quality 

sampling frequency was reduced from six samples per year 

(1998 through 2002) to four samples per year (2003 through 

2006). Routine water-quality samples were collected in 

February, May, July, and October. Routine samples were 

collected at scheduled times with little regard for hydrologic 

conditions. Therefore, routine samples collected during May 

and July could also be considered storm samples. Storm 

samples specifically targeted conditions during stormflow. 

Stormflow samples were collected annually between April 

1 and September 30. The frequency of storm sampling was 

reduced from four samples per year (1998 through 2002) to 

two samples per year during 2003 through 2006. Water-quality 

samples also were collected on selected tributaries to Fountain 

and Monument Creeks. Three sites on Cottonwood Creek 

sampled during 1998 through 2002 were supplemented with 

10 sites on 7 additional tributaries during 2003 through 2006. 

The additional sites included two sites on Kettle Creek, one 

site on Pine Creek, one site on North Rockrimmon Creek, two 

sites on Mesa Creek, one site on an unnamed tributary, two 

sites on Bear Creek, and one site on Sand Creek. These sites 

were added to better characterize variations in water quality 

and suspended sediment during nonstorm and storm periods. 

Two routine water-quality samples during normal flow were 

collected annually, one time each in June and October. One 

storm sample was collected from each tributary between 

April 1 and September 30. The sampling routine for Sand 

Creek was different from the other tributary sites. Two routine 

water-quality samples were collected in March and July, 

and two storm samples were collected between April 1 and 

September 30.

   Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Figure 1. Location of study area and sampling sites for the Fountain and Monument Creek watersheds.

07104000 (MoCr_Pikeview)

07104050 (RkCr)

07103700

(FoCr_Manitou)

07103990 (lower_CoCr)

385750104475001 (PiCr)

385501104483701 (TbMo)

07103985 (TbCo)

07104905 (MoCr_Bijou)

07103707 (FoCr_8th)

385204104510101 (upper_MeCr)

385124104501301 (lower_MeCr)

07103977 (upper_CoCr)

07103960 (lower_KeCr)

07103980 (middle_CoCr) 07103970

(MoCr_Woodmen)

385854104470100

(upper_KeCr)

07105000 (upper_BeCr)

07105600 (SaCr)

07105500 (FoCr_Nevada)

07105800 (FoCr_Security)

384909104504401

(lower_BeCr)

07105530 (FoCr_Janitell)

07104000 (MoCr_Pikeview)

07104050 (RkCr)

07103700

(FoCr_Manitou)

07103990 (lower_CoCr)

385750104475001 (PiCr)

385501104483701 (TbMo)

07103985 (TbCo)

07104905 (MoCr_Bijou)

07103707 (FoCr_8th)

385204104510101 (upper_MeCr)

385124104501301 (lower_MeCr)

07103977 (upper_CoCr)

07103960 (lower_KeCr)

07103980 (middle_CoCr) 07103970

(MoCr_Woodmen)

385854104470100

(upper_KeCr)

07105000 (upper_BeCr)

07105600 (SaCr)

07105500 (FoCr_Nevada)

07105800 (FoCr_Security)

384909104504401

(lower_BeCr)

07105530 (FoCr_Janitell)

07105800

Sand Creek

Monument Creek

Bear Creek

Kettle Creek

Pine Creek

Cottonwood Creek

Sand Creek

Cottonwood Creek

Fountain Creek

North Rockrimmon Cr

Mesa Creek

Front Range of Southern Rocky Mountains

Rampart Range

Colorado Piedmont

EXPLANATION

Military base or reservation

Municipal area

Sampling site and number (site abbreviation)

104°55' 104°45'

38°45'

39°

COLORADO

Study

area

Denver

Fort Carson

Military Reservation

Las Vegas

Street Wastewater

Treatment Plant

Security Wastewater

Treatment Plant

US Air Force 

Academy

Peterson Air 

 Force Base

0 1.5

0 1.5 3 KILOMETERS

Approximate boundary between Colorado Piedmont 

and Front Range of Southern Rocky Mountains 

physiographic regions

Watershed

boundary

Colorado Springs

Manitou Springs El Paso County

Teller County

Base from U.S. Geological Survey

Albers Equal-Area Conic projection

Standard parallels 37°30’N and 40°30’N

Central meridian 105°30’W

3 MILES

Introduction 
Table 1. Selected surface-water sites in the Fountain and Monument Creek watersheds, and biological properties, water-quality constituents and suspended sediment 

measured or analyzed, and channel geometry surveys, 1981 through 2006.—Continued[FoCr, Fountain Creek; MoCr, Monument Creek; KeCr, Kettle Creek; PiCr, Pine Creek; CoCr, Cottonwood Creek; RkCr, North Rockrimmon Creek; TbCo, tributary to Cottonwood Creek; TbMo, tributary to Monument Creek; MeCr, Mesa Creek; BeCr, Bear Creek; SaCr, Sand Creek; E. coli, Escherichia coli; X, routine sampling; --, not sampled; P, periodic measurements; S, storm sampling and routine sampling; D, daily data; C, data collected by Colorado Springs City Engineering personnel, 1999–2006; U, data collected by U.S. Geological Survey personnel, 2003–2006]

U.S. Geological Survey site 

number and site abbreviation1 Site name1 Site type Period of data collection

5-day 

Biochemical 

oxygen 

demand

Bacteria, 

Fecal 

coliform 

and 

E. coli

Nutrients Trace elements Sus- pended sediment Cross- section surveys

07103700, FoCr_Manitou Fountain Creek near Colorado Springs Main stem 1981-2006 S S S S P2 C07103707, FoCr_8th Fountain Creek below 8th 

Street

Main stem 1981, 

1998-2006

X

X

X

X

P --

385854104470100, upper_KeCr Kettle Creek abv Old Ranch 

Road

Tributary to Monument 

Creek

2003-2006 -- S S --

P --

07103960, lower_KeCr Kettle Creek abv USAFA Tributary to Monument 

Creek

2003-2006 -- S S --

P --

385750104475001, PiCr Pine Creek abv Highway 83 Tributary to Monument 

Creek

2003-2006 -- S S --

P --

07103970, MoCr_Woodmen Monument Creek abv Woodmen Road Main stem 1998-2006 S S S S D

C

07103977, upper_CoCr Cottonwood Creek at Cowpoke Road Tributary to Monument Creek 1998-2006 -- S S --

P2 C

07103980, middle_CoCr Cottonwood Creek at Woodmen Road Tributary to Monument Creek 1998-2006 -- -- S --

P2 C

07103985, TbCo Cottonwood Creek tributary 

at Rangewood Drive

Tributary to Monument 

Creek

1998-2006 -- S S --

P2 C

07103990, lower_CoCr Cottonwood Creek at Mouth Tributary to Monument 

Creek

1998-2006 -- S S --

D

C

07104000, MoCr_Pikeview Monument Creek at Pikeview Main stem 2003-2006 -- -- -- -- --

U

07104050, RkCr North Rockrimmon Creek 

abv Delmonico Dr.

Tributary to Monument 

Creek

2003-2006 -- S S --

P

C

385501104483701, TbMo Monument Creek tributary 1 

near Pulpit Rock

Tributary to Monument 

Creek

2003-2006 -- S S --

P --

385204104510101, upper_MeCr Mesa Creek below Filmore 

Street

Tributary to Monument 

Creek

2003-2006 -- S S --

P --

 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Table 1. Selected surface-water sites in the Fountain and Monument Creek watersheds, and biological properties, water-quality constituents and suspended sediment 

measured or analyzed, and channel geometry surveys, 1981 through 2006.—Continued[FoCr, Fountain Creek; MoCr, Monument Creek; KeCr, Kettle Creek; PiCr, Pine Creek; CoCr, Cottonwood Creek; RkCr, North Rockrimmon Creek; TbCo, tributary to Cottonwood Creek; TbMo, tributary to Monument Creek; MeCr, Mesa Creek; BeCr, Bear Creek; SaCr, Sand Creek; E. coli, Escherichia coli; X, routine sampling; --, not sampled; P, periodic measurements; S, storm sampling and routine sampling; D, daily data; C, data collected by Colorado Springs City Engineering personnel, 1999–2006; U, data collected by U.S. Geological Survey personnel, 2003–2006]

U.S. Geological Survey site 

number and site abbreviation1 Site name1 Site type Period of data collection

5-day 

Biochemical 

oxygen 

demand

Bacteria, 

Fecal 

coliform 

and 

E. coli

Nutrients Trace elements Sus- pended sediment Cross- section surveys

385124104501301, lower_MeCr Mesa Creek at Sondermann 

Park

Tributary to Monument 

Creek

2003-2006 -- S S -- P --

07104905, MoCr_Bijou Monument Creek at Bijou 

Street

Main stem 1981-2006 S S S S D3 U

07105000, upper_BeCr Bear Creek near Colorado 

Springs

Tributary to Fountain Creek 1992-2006 -- S S S P --

384909104504401, lower_BeCr Bear Creek above 8th Street Tributary to Fountain Creek 2003-2006 -- S S -- P --07105500, FoCr_Nevada Fountain Creek at Colorado 

Springs

Main stem 1981-2006 S S S S D C

07105530, FoCr_Janitell Fountain Creek below 

Janitell Rd.

Main stem 1981-2006 S S S S P U

07105600, SaCr Sand Creek above Mouth Tributary to Fountain Creek 2003-2006 -- S S -- D3 C07105800, FoCr_Security Fountain Creek at Security Main stem 1981-2006 S S S S D C

1Site name and abbreviation used in this report.2Daily data collection discontinued after 2002.3Data collected 2003 through 2006.

Introduction   
Measurements of specific conductance, pH, dissolved 

oxygen, biochemical oxygen demand (BOD5), fecal coliform 

and Escherichia coli (E. coli), nitrogen, phosphorus, and 

selected trace elements were used to describe the water quality 

in the Fountain and Monument Creek watersheds in the 

vicinity of Colorado Springs, Colorado.

Suspended-sediment samples were collected in 

conjunction with routine and stormwater-quality samples to 

evaluate variations in suspended-sediment concentrations, 

discharge, and yield. Samples were collected from April 1 

through September 30 during the period 1998 through 

2005. In addition to periodic routine and storm suspendedsediment samples, samples were collected daily by 

automatic samplers at Monument Creek above Woodmen 

(site 07103970, MoCr_Woodmen), Cottonwood Creek at the 

mouth (site 07103990, lower_CoCr), Monument Creek at 

Bijou Street (site 07104905, MoCr_Bijou), Fountain Creek at 

Colorado Springs (site 07105500, FoCr_Nevada), Sand Creek 

above mouth (site 07105600, SaCr), and Fountain Creek at 

Security (site 07105800, FoCr_Security) to evaluate daily 

variations in suspended-sediment concentrations, discharge, 

and yield. Automatic samplers were operated annually from 

April 1 through September 30. Periodic and daily samples 

were used to evaluate annual and spatial variations in 

suspended-sediment concentrations, discharge, and yield that 

occurred during base flow, normal flow, and stormflow to 

determine relative source areas of sediment in the watershed.

Changes in channel morphology were assessed by 

surveying cross sections at selected locations on Fountain and 

Monument Creeks, Cottonwood Creek, North Rockrimmon 

Creek, and Sand Creek. Selected reaches at 10 sites (table 1) 

were surveyed annually by Colorado Springs City Engineering 

employees. Selected cross sections at three sites (table 1) were 

surveyed multiple times during the year by U.S. Geological 

Survey employees.

Description of Study Area

The study area has a drainage area of about 500 mi2 and 

encompasses most of the urbanized area within the Fountain 

and Monument Creek watersheds. Elevations in the study 

area range from 14,109 ft at the summit of Pikes Peak to 

5,460 ft at the southern end of the study area. There are two 

major physiographic regions in the study area—the Front 

Range of the Southern Rocky Mountains and the Colorado 

Piedmont (Hansen and Crosby, 1982). The Front Range, 

which comprises about the western one-third of the study 

area, is underlain by granite. Soils in this area are well drained 

and lie on steep slopes (Larsen, 1981; von Guerard, 1989a). 

The Colorado Piedmont, which comprises the remaining 

eastern two-thirds of the area, abuts the base of the Rampart 

Range and is underlain by sandstone, shale, and alluvial and 

windlain deposits. Soils in this area generally are sandy and 

well drained with gentler slopes (Larsen, 1981; von Guerard, 

1989a). The soils and geology on the Colorado Piedmont are 

readily erodible, especially relative to the granitic rocks on 

the west side of the study area. More details of the soils and 

geology of the study area are contained in Larsen (1981) and 

von Guerard (1989a).

The population of El Paso County, which includes 

Colorado Springs, has increased from about 70,000 people 

in 1950 to about 310,000 in 1980, to about 510,000 in 2000 

(U.S. Census Bureau, 2007). The 2006 population is estimated 

at about 562,000. The rate of growth, about 8,000 people per 

year, was fairly constant between 1950 and 1990. Between 

1990 and 2000, the rate of growth increased to about 

11,000 people per year (Stogner, 2000). In recent years the 

rate of growth has slowed to about 8,600 people per year (The 

Gazette, 2006). This report uses data collected at 22 sites 

throughout the Fountain and Monument Creek watersheds 

and frequently refers to site identification numbers to provide 

a spatial reference. An abbreviated naming convention for 

each site was developed to assist the reader and is linked to 

the creek where the site is located (table 1). For example, 

site 07104905 (MoCr_Bijou) refers to site 07104905, located 

on Monument Creek at Bijou Street.

Land Use

Land uses within the study area include agriculture, 

commercial, industrial, residential, streets and easements, 

airports and military reservations, and undeveloped areas. 

Substantial changes in land use have occurred from increased 

population. Table 2 shows estimated impervious area and 

the total area for various land-use categories for 1997, 

2001, and 2005 in the Fountain and Monument Creek 

watersheds. Estimates of the total impervious area were 

based on coefficients developed from Pikes Peak Area 

Council of Governments (PPACG) (2005). Estimates of the 

percentage of impervious and pervious material associated 

with each land use were applied using coefficients adopted 

from PPACG (2005) (table 3). The percent imperviousness 

(4 percent of agricultural, 20–98 percent of commercial, 

35–85 percent of industrial, 12–65 percent of residential, 

10–98 percent of streets and easements, 13 percent of airports 

and military reservations, and 2–4 percent of undeveloped 

land-use categories) varied based on parcel size and landuse subcategory definitions. Land-use data for 1997 through 

2005 were provided by the City of Colorado Springs. A 

Geographic Information System (Environmental Systems 

Research Institute, Inc., 2005) was used to compute area and 

imperviousness of land-use categories and subcategories. 

The amount of estimated impervious area within El Paso 

County (fig. 1) upstream from site 07105800 (FoCr_Security) 

increased from 68.8 mi2 in 1997 and 75.7 mi2 in 2001 to about 

80 mi2 in 2005 (table 2).

   Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Table 2. Land uses and estimated total impervious area for the Fountain and Monument Creek watersheds in El Paso County, Colorado, 1997, 2001, and 2005 (land-use data 

provided by the City of Colorado Springs).[Ag, agriculture; Com, commercial; Ind, industrial; Res, residential; ROW, streets and easements; A&M, airports and military; Und, undeveloped; mi2, square miles; --, category not reported]

Site number1

Drainage 

area2

(mi2)

Ag

(mi2)

Com

(mi2)

Ind

(mi2)

Res

(mi2)

ROW

(mi2)

A&M

(mi2)

Und

(mi2)

Impervious 

area 

(mi2)

Percent 

impervious

1997

07103700 103 0.788 4.47 0.273 7.54 2.48 -- 55.1 7.75 7.5207103707 118 1.19 6.36 .618 9.68 3.69 -- 64.7 10.4 8.81385854104470100 15.4 2.13 1.07 .129 8.98 .627 -- 2.47 2.31 15.007103960 16.2 2.15 1.09 .138 9.30 .707 0 2.78 2.43 15.0385750104475001 3.61 1.26 .048 .014 .131 .099 -- 2.06 .203 5.6207103970 180 24.3 4.05 .593 28.5 6.35 28.9 87.4 17.1 9.5007103977 5.84 2.62 .047 .007 2.03 .162 -- .974 .504 8.6307103980 10.2 4.17 .232 .031 2.66 .504 -- 2.60 1.08 10.607103985 2.80 .702 .086 .076 .428 .243 -- 1.27 .397 14.207103990 18.7 4.88 .711 .318 5.56 1.78 -- 5.41 3.23 17.307104000 203 29.3 5.09 .959 35.8 8.65 28.9 94.8 21.3 10.507104050 1.82 0 .078 .005 1.03 .247 -- .459 .476 26.2385501104483701 .691 0 .067 .001 .257 .070 -- .296 .171 24.7

385204104510101 .768 .004 .075 .071 .180 .053 -- .386 .181 23.6

385124104501301 2.05 .009 .125 .071 .479 .105 -- 1.26 .335 16.307104905 228 31.1 6.96 3.17 41.5 11.9 28.9 104 27.9 12.2

07105000 6.92 0 .324 -- .033 -- -- 6.55 .362 5.23384909104504401 9.57 0 .359 .021 .843 .226 -- 8.10 .703 7.35

07105500 384 32.3 14.5 4.14 54.4 17.2 28.9 200 41.6 10.8

07105530 412 32.4 18.3 4.78 65.6 23.7 28.9 206 51.8 12.607105600 52.6 21.6 1.63 1.60 10.8 4.34 .760 11.9 8.38 15.9

07105800 499 56.3 22.2 8.21 82.4 32.5 38.7 227 68.8 13.8

Introduction 
Table 2. Land uses and estimated total impervious area for the Fountain and Monument Creek watersheds in El Paso County, Colorado, 1997, 2001, and 2005 (land-use data 

provided by the City of Colorado Springs).—Continued[Ag, agriculture; Com, commercial; Ind, industrial; Res, residential; ROW, streets and easements; A&M, airports and military; Und, undeveloped; mi2, square miles; --, category not reported]

Site number1

Drainage 

area2

(mi2

)

Ag

(mi2

)

Com

(mi2

)

Ind

(mi2

)

Res

(mi2

)

ROW

(mi2

)

A&M

(mi2

)

Und

(mi2

)

Impervious 

area 

(mi2

)

Percent 

impervious

2001

07103700 103 1.05 3.72 0.226 7.53 4.47 -- 53.7 9.91 9.6207103707 118 1.45 5.61 .437 9.76 5.65 -- 63.3 12.4 10.5385854104470100 15.4 2.03 .906 .135 9.61 .658 -- 2.06 2.37 15.407103960 16.2 2.12 .928 .207 9.96 .757 0 2.20 2.56 15.8385750104475001 3.61 1.53 .134 .044 .381 .244 -- 1.28 .422 11.707103970 180 19.8 4.31 .883 31.7 7.34 28.9 87.4 18.5 10.307103977 5.84 2.12 .048 .009 2.29 .233 -- 1.14 .568 9.7307103980 10.2 3.82 .216 .033 3.15 .769 -- 2.21 1.3 12.707103985 2.80 .178 .211 .076 .745 .433 -- 1.16 .646 23.107103990 18.7 4 .925 .334 6.62 2.3 -- 4.49 3.89 20.807104000 203 23.7 5.61 1.28 40.1 10.2 28.9 93.7 23.5 11.607104050 1.82 -- .077 .005 1.09 .245 -- .409 .487 26.8385501104483701 .69 -- .067 .001 .294 .08 -- .249 .184 26.6385204104510101 .77 -- .076 .071 .214 .029 -- .378 .186 24.2385124104501301 2.05 -- .135 .071 .496 .088 -- 1.26 .345 16.807104905 228 25.4 7.73 3.62 46.3 13.5 28.9 102 30.5 13.407105000 6.92 -- -- -- .033 -- -- 6.87 .159 2.30384909104504401 9.57 -- .030 .021 .922 .237 -- 8.34 .520 5.4307105500 384 26.9 14.5 4.38 61.5 20.8 28.9 195 46.5 12.107105530 412 27 18.4 5.11 72.9 27.4 28.9 200 57.0 13.807105600 52.6 20.2 2.2 1.81 12.2 4.82 .760 10.6 9.49 18.007105800 499 49.4 23 8.78 91.6 37.1 38.7 218 75.7 15.2

   Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Table 2. Land uses and estimated total impervious area for the Fountain and Monument Creek watersheds in El Paso County, Colorado, 1997, 2001, and 2005 (land-use data 

provided by the City of Colorado Springs).—Continued[Ag, agriculture; Com, commercial; Ind, industrial; Res, residential; ROW, streets and easements; A&M, airports and military; Und, undeveloped; mi2, square miles; --, category not reported]

Site number1

Drainage 

area2

(mi2)

Ag

(mi2)

Com

(mi2)

Ind

(mi2)

Res

(mi2)

ROW

(mi2)

A&M

(mi2)

Und

(mi2)

Impervious 

area 

(mi2)

Percent 

impervious

2005

07103700 103 1.20 3.73 0.213 8.22 3.50 -- 53.8 9.53 9.2507103707 118 1.60 5.58 .449 10.4 4.71 -- 63.5 12.1 10.3385854104470100 15.4 1.79 .902 .135 9.87 .809 -- 1.91 2.49 16.207103960 16.2 1.87 .925 .207 10.2 .903 0 2.01 2.69 16.6385750104475001 3.61 1.12 .169 .044 .617 .523 -- 1.14 .659 18.307103970 180 19.4 4.93 .919 34.3 8.88 28.9 82.9 20.4 11.3

07103977 5.84 2.00 .040 .002 2.65 .243 -- .906 .601 10.307103980 10.2 3.43 .339 .035 3.60 .943 -- 1.85 1.54 15.107103985 2.80 .13 .231 .030 1.10 .545 -- .767 .817 29.207103990 18.7 3.56 1.13 .274 7.66 2.59 -- 3.44 4.41 23.607104000 203 22.9 6.45 1.26 43.8 12.0 28.9 88.0 25.9 12.807104050 1.82 -- .087 .005 1.10 .249 -- .385 .497 27.3

385501104483701 .69 -- .073 .001 .336 .080 -- .200 .203 29.4385204104510101 .77 -- .057 .087 .194 .068 -- .361 .194 25.3

385124104501301 2.05 -- .117 .087 .501 .132 -- 1.21 .370 18

07104905 228 24.6 8.67 3.60 50.3 15.3 28.9 96.4 33.1 14.507105000 6.92 -- -- -- .033 .000 -- 6.87 .159 2.3

384909104504401 9.57 .000 .005 .013 .983 .241 -- 8.31 .511 5.3407105500 384 26.3 15.4 4.35 64.0 21.7 28.9 191 48.5 12.6

07105530 412 26.4 19.5 5.04 75.7 28.4 28.9 196 59.2 14.4

07105600 52.6 17.9 2.59 2.04 13.6 5.82 .760 9.95 10.9 20.707105800 499 46.3 24.4 8.97 96.5 39.2 38.8 213 79.8 16

1See figure 1.2Drainage area computed from accumulating land uses provided by the City of Colorado Springs.

Introduction   
Table 3. Imperviousness coefficients for land-use categories and subcategories in the Fountain 

and Monument Creek watersheds.—Continued

[du, development unit, R&D, research and development; res, residential; ROW, streets and easements]

Land-use category Land-use subcategory Imperviousness 

coefficient

agriculture Agriculture 4

agriculture Special purpose 4

airports and military Airport/military installation 13

commercial Office low 20

commercial Office medium 35

commercial Primary/Secondary school 35

commercial University/conference center 35

commercial Parking/vacant 60

commercial Commercial services 70

commercial Common commercial 70

commercial Community commercial 70

commercial Exempt & undefinable 70

commercial Major public assembly 70

commercial Minor public assembly 70

commercial Neighborhood commercial 70

commercial Undefined institutional use 70

commercial Unspecified commercial 70

commercial Unspecified office 70

commercial Detention center 85

commercial Fire station 85

commercial Highway-oriented commercial 85

commercial Hospital 85

commercial Library 85

commercial Museum 85

commercial Office high 85

commercial Police 85

commercial Public safety 85

commercial Regional commercial 85

commercial Parking lot/black top 98

commercial Parking structure 98

industrial Office-Industrial Park/R&D 35

industrial General industrial 70

industrial Industrial 70

industrial Warehouse/wholesale 70

10 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Table 3. Imperviousness coefficients for land-use categories and subcategories in the Fountain 

and Monument Creek watersheds.—Continued

[du, development unit, R&D, research and development; res, residential; ROW, streets and easements]

Land-use category Land-use subcategory Imperviousness 

coefficient

industrial Mining 85

residential 0-1.99 res. du/acre 12

residential 2.0-3.49 res du/acre 21

residential 3.5-7.99 res du/acre 28

residential Unspecified density (res) 33

residential Unspecified density (res) 33

residential Unspecified density (res) 33

residential 12.0-24.99 res du/acre 39

residential 25+ res du/acre 39

residential 8.0-11.99 res du/acre 39

residential Common residential area 65

residential Condo/Townhome 65

streets and easements Undefined public use 10

streets and easements Other public street ROW 60

streets and easements Private street ROW 60

streets and easements Undefined easement 60

streets and easements Undefined street ROW 60

streets and easements Unspecified ROW/Easement 60

streets and easements Utility easement/ROW/Facil 60

streets and easements Collector street ROW 85

streets and easements Undefined street ROW 85

streets and easements Arterial street 98

streets and easements Drainage easement, and so forth 98

undeveloped Cemetery 2

undeveloped Community park 2

undeveloped Golf course 2

undeveloped Neighborhood park 2

undeveloped Open space 2

undeveloped Regional park 2

undeveloped Trail 2

undeveloped Undefined - open space 2

undeveloped Undefined park 2

undeveloped Vacant land 2

undeveloped Sports complex 4

Introduction 11
Acknowledgments

The authors appreciate the efforts of those who assisted 

in the collection of these data. Thanks to Lisa Ross, Colorado 

Springs City Engineering, for help with planning and support 

for the monitoring program. Thanks also to Joel Mackey 

and GIS staff at Colorado Springs City Engineering for their 

cooperation and support and for providing land-use and crosssection survey data and to Richard Muzzy, Pikes Peak Area 

Council of Governments, for assistance with developing landuse imperviousness coefficients. Finally, thanks to Lauri Krall, 

Sheryl Ferguson, Erin Evans, Wade Walker, Nick Young, R.J. 

Ortiz, John Ragulsky, Krystal Tezak, and Jason Stewart, U.S. 

Geological Survey, for their dedication and tireless efforts 

in the collection and processing of stormflow samples under 

harsh field conditions.

Methods of Investigation

Flow Regime

Water quality commonly varies with different streamflow 

regimes. As stated previously, streamflow in the Fountain and 

Monument Creek watersheds varies seasonally; therefore, for 

purposes of this report, water-quality data were separated into 

three flow regimes: base flow, normal flow, and stormflow. 

Water-quality samples collected between November 1 and 

April 30 that were unaffected by stormflow were identified 

as base-flow samples. Water-quality samples collected during 

the remainder of the year that were unaffected by stormflow 

were identified as normal-flow samples. Samples that were 

collected during storm runoff were identified as stormflow 

samples. Water-quality data associated with base flow, normal 

flow, and stormflow were compared to characterize variations 

in water quality that exist among the different flow regimes. 

Water-quality data determined to have been associated 

with stormflow were identified by visual inspection of the 

hydrograph, available precipitation data, and water-quality 

concentration and sediment data and by using a 

base-flow-separation program (Wahl and Wahl, 1995).

Discharges generally were obtained from streamflow 

measurements at USGS streamflow-gaging stations. 

Streamflow at gaging stations is estimated after developing 

the relation of stage to streamflow for a particular location 

(Buchanan and Somers, 1968; Carter and Davidian, 1968; 

Kennedy, 1983, 1984). At a typical USGS streamflow-gaging 

station, stream stage, or the level of water in the stream, is 

recorded at periodic intervals. Based on a relation between 

stage and streamflow, recorded stream stage is used to 

estimate streamflow. Streamflow data used in this report are 

available from the USGS National Water Information System 

(NWIS) (2007).

Water-Quality Data

Water-quality data were collected and processed using 

standard USGS techniques and procedures (U.S. Geological 

Survey, 1977; Sylvester and others, 1990; Horowitz and 

others, 1994; Wilde and others, 1998). Since 1994, sampling 

equipment has been cleaned using the part-per-billion 

protocols. Field measurements that are discussed in this report 

are specific conductance, pH, and dissolved oxygen. Water 

samples collected between 1981 and 1997 were analyzed by 

the USGS National Water-Quality Laboratory (NWQL), 

Lakewood, Colorado. Water samples collected between 1998 

and 2002 were analyzed by the Colorado Springs Utilities 

Environmental Quality Laboratory with quality-control 

samples analyzed by the NWQL. Water-quality data from the 

Colorado Springs Utilities Environmental Quality Laboratory 

that were used in this report were comparable to the waterquality data analyzed by the NWQL. Beginning in 2003 all 

water-quality data were collected and analyzed at the NWQL. 

Samples for analysis of 5-day biochemical oxygen demand 

(BOD5) were collected at seven main-stem sites in the study 

area. Samples collected for biochemical oxygen demand 

were processed in the USGS Colorado Water Science Center 

Pueblo office laboratory (USGS Pueblo laboratory) until 1997, 

Colorado Springs Utilities Environmental Quality Laboratory 

from 1998 until 2002, and then the USGS Pueblo laboratory 

beginning in 2003. Water-quality data used in this report are 

available from the USGS National Water Information System 

(NWIS) (2007).

Quality-control samples were routinely collected 

and analyzed to identify, quantify, and document bias and 

variability in the collection and processing of data. Sample 

processing was done primarily in a mobile USGS laboratory 

located at the sampling site; therefore, field blanks were 

collected to measure the environmental conditions in the 

mobile laboratory. Quality-control samples were submitted 

to the appropriate laboratory for analysis. Blank samples 

analyzed for inorganic constituents were prepared with 

inorganic grade water from the USGS Ocala (Florida) Field 

Services Unit or NWQL where the water is quality assured 

for suitability in the testing of equipment and sampling. In 

addition to blank samples, several replicate samples were 

collected to assess the variability among samples resulting 

from collection, processing, and laboratory procedures 

conducted at different sampling times (Wilde and others, 

1998).

Results from field blanks for constituents analyzed in this 

report indicated that field blanks were free of contamination. 

There were isolated instances of detections of dissolved 

ammonia that were near the laboratory analytical detection 

limit, but these detections were not considered to affect sample 

integrity. There also were isolated instances of low-level 

detections of dissolved boron and dissolved selenium. 

Dissolved boron was detected once during 2001 at 0.01 mg/L, 

12 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Outlier value

Outside value

Largest value within 1.5 times the IQR 

75th percentile

Median IQR

Smallest value within 1.5 times the IQR

25th percentile

and dissolved selenium was detected once in 2000 at a 

concentration of 2.0 μg/L.

The mean relative percentage difference in replicate 

samples ranged from about 7 percent for nutrient concentrations to about 11 percent for trace-element concentrations. 

Relative percentage difference was calculated as the absolute 

difference between the replicate and original sample concentrations divided by the average of the two values, multiplied by 

100. When constituent concentrations are low, small absolute 

differences between the original and replicate sample result in 

larger relative percentage differences. Overall, the magnitude 

of the difference was within 10 percent for most constituents.

Suspended-Sediment Data

Suspended-sediment samples generally were collected 

daily from April through September each year from 1998 

through 2005 at six sites (table 1). Suspended-sediment 

samples were manually collected as described by Edwards and 

Glysson (1988) and analyzed at the USGS Iowa Water Science 

Center Sediment Laboratory, Iowa City, Iowa. Discrete point 

samples were collected using automatic samplers installed at 

selected streamflow gages that were programmed to collect 

samples daily and during rises in stream stage. Suspendedsediment concentrations obtained from samples collected at 

a single point within the cross section were adjusted on the 

basis of relations developed from depth-integrated samples 

collected periodically using the equal-width-increment 

method (Koltun and others, 1994). For data collected between 

1998 and 2000, daily suspended-sediment concentration and 

streamflow were subdivided using the SEDCALC program 

with the linear interpolation, uneven time interval option to 

compute the daily mean suspended-sediment concentration 

and discharge (Koltun and others, 1994). For data collected 

since 2001, the same procedure was done using the GCLAS 

program (Koltun and others, 2006). Suspended-sediment data 

for samples that were collected manually are available from 

the USGS National Water Information System (NWIS) (2007); 

suspended-sediment data for discrete point samples collected 

using automatic samplers are available upon request from the 

USGS Colorado Water Science Center Pueblo office.

Boxplots

Water-quality and suspended-sediment data presented 

in this report are summarized using boxplots. Boxplots 

graphically display the constituent variability and provide an 

easy method for comparing spatial, temporal, and flow-related 

data. Boxplots are useful because the variability between data 

sets, unusual values, and selected summary statistics are easily 

observed. Boxplots contain the following information. The 

horizontal line within the box represents the median value 

(50 percent of the data are larger than this value and 

50 percent of the data are less than this value). The lower 

horizontal line of the box is the 25th percentile or lower 

quartile (25 percent of the data are less than this value). The 

upper horizontal line of the box is the 75th percentile or upper 

quartile (75 percent of the data are less than this value). The 

interquartile range (IQR) contains the values between the 25th 

and 75th percentiles and is the difference between the 25th 

and 75th percentiles. The bottom of the vertical line on the 

boxplot is the smallest value within 1.5 times the IQR of the 

box. The top of the vertical line on the boxplot is the largest 

value within 1.5 times the IQR of the box. Outside values are 

larger than 1.5 times the IQR from the box and outlier values 

are larger than 3 times the IQR from the box. An example of a 

boxplot is shown here:

Statistical Analyses

Parametric and nonparametric statistical analyses were 

applied to the data to compare relations between selected 

water-quality constituents and to evaluate spatial and temporal 

differences in water quality and suspended sediment. The 

Tukey analysis used in this report is a parametric multiple 

comparison test based on rank-transformed data (to approximate a normal distribution) and was used to identify statistical 

differences in selected water-quality constituents among 

various sites and flow regimes. Results from the Tukey 

analysis provide the statistical significance of those trends 

(Helsel and Hirsch, 1992).

Nonparametric analyses used in this report included the 

Spearman’s rho correlation test, the Kruskal-Wallis test of 

independent groups, the Kendall’s tau test, and the MannWhitney test (Helsel and Hirsch, 1992). Nonparametric tests 

use ranks of data as opposed to real data values and are used if 

data are not normally distributed and if parametric statistical 

techniques are skewed by large outliers. Spearman’s rho test 

was used to determine corre­lation between land-use categories 

and water-quality constituents. The Kruskal-Wallis test was 

used to determine whether there was a statistical difference 

between the medians of two independent groups. The test was 

used in this report to deter­mine if the data collected between 

two periods, 1981 through 1997 and 1998 through 2006, 

were signif­icantly different. The Kendall’s tau test was used 

to determine whether a trend occurred with precipitation over 

time. The Mann-Whitney test was used to determine whether 

there were spatial and temporal differences for suspendedMethods of Investigation 13
sediment concentrations, discharge, and suspended-sediment 

yields. The probability of error (p-value) was used in this 

report to determine the significance of statistical tests for all 

statistical methods. A p-value of less than 0.05 (95-percent 

confidence that the statistical test is valid, or that the compared 

data sets are different) was used in this report to indicate if a 

sta­tistical test was significant.

Precipitation and Streamflow

Annual precipitation in the Fountain and Monument 

Creek watersheds generally decreases with distance from the 

headwaters of the watershed and as elevation decreases. The 

mean annual precipitation varies considerably from year to 

year. At the Colorado Springs Weather Service Office (WSO) 

at Peterson Air Force Base (fig. 1), annual precipitation for 

1949 through 2006 ranged from 7.8 to 27.6 inches (fig. 2). 

Annual precipitation increased significantly between 1949 

and 2001 (p<0.05). The mean annual precipitation increased 

from 14.9 inches from 1949 through 1980 to 18.5 inches from 

1981 through 2001. The mean annual precipitation decreased 

to 13.5 inches for the period 2001 through 2006, primarily 

due to the 2002 drought conditions. However, even when 2002 

was removed from the calculation of the mean, the Colorado 

Springs area received on average 14.5 inches of precipitation 

during the most recent period, which is similar to the recorded 

mean precipitation from 1949 through 1980 (14.9 inches). 

Between 1998 and 2006, when most of the data used in this 

report were collected, the annual precipitation ranged from 

7.8 inches in 2002 to 27.6 inches in 1999, which represents 

the minimum and the maximum annual precipitation for the 

52-year period of record. Convective thunderstorms contribute 

most of the rainfall during May through September. Based 

on 1998 through 2006 precipitation data, about 79 percent of 

the daily precipitation that occurs is less than 0.25 inch, about 

13 percent is between 0.26 and 0.5 inch, about 3 percent is 

between 0.51 and 0.75 inch, about 2 percent is between 0.76 

and 1 inch, and about 3 percent is larger than 1 inch. These 

data indicate that daily precipitation larger than 0.25 inch 

occurs an average of 77 days each year; daily precipitation 

larger than 0.5 inch occurs an average of 28 days each year; 

and daily precipitation larger than 1 inch occurs an average of 

10 days each year. The precipitation values breakdown from 

1998 through 2006 is similar to the values for the period 1981 

through 1997, with the exception that precipitation larger than 

0.5 inch decreased 20 percent during the 1998 through 2006 

period. Between 1998 and 2006, the number of runoff events 

per year generally ranged from 70 to 90, with an average of 

84.

The three flow regimes, base flow, normal flow, and 

stormflow, were applied to streamflow in the Fountain and 

Monument Creek watersheds. During base flow, streamflow 

is fairly uniform and is sustained by ground-water discharge, 

wastewater effluent, and other regulated discharges. Normal 

flow generally begins in May with the onset of snowmelt 

and extends into October. Streamflow during normal flow is 

highly variable. Changes in streamflow during the summer are 

primarily caused by convective thunderstorms. Stogner (2000) 

evaluated trends in streamflow regimes from 1977 through 

1999. Significant increases in high-streamflow and lowstreamflow regimes were detected at most sites on Fountain 

and Monument Creeks in the study area during this time 

period.

As part of this study, the number of stormflow events 

from May through October for each year were estimated 

from 1981 through 2006 by using a program to separate the 

base-flow component from the daily mean streamflow (Wahl 

and Wahl, 1995). The program implements a deterministic 

procedure to estimate the base-flow component of the daily 

hydrograph by combining a local minimums approach with 

a recession slope test. Based on inspection of streamflow 

hydrographs, a decision was made that daily mean streamflow 

larger than 2 times the computed daily base flow was a 

conservative indicator of stormflow for all main-stem sites. 

For the tributary sites, a decision was made that daily mean 

streamflow larger than 3 times the computed daily base flow 

was a conservative indicator of stormflow.

Instantaneous streamflow measurements made during 

water-quality sampling varied by site and flow regime. In 

addition, certain sites and flow regimes were significantly 

different between 1981 through 1997 and 1998 through 2006 

(fig. 3). Streamflow for Fountain and Monument Creeks 

at main-stem sites during 1998 through 2006 generally 

increased from upstream to downstream for all flow regimes. 

On Fountain Creek, upstream from the confluence with 

Monument Creek, streamflow is diverted upstream from 

site 07103707 (FoCr_8th), reducing median normal flow 

from 15.0 ft3/s to 3.2 ft3/s (fig. 3A). On Monument Creek, 

upstream from the confluence of Fountain and Monument 

Creeks, median normal flow increased between the upstream 

site, 07103970 (MoCr_Woodmen), and the downstream site, 

07104905 (MoCr_Bijou), by more than 80 percent from 11 

to 20 ft3/s. Median stormflow discharge that was sampled 

for water-quality constituents between those same two sites 

increased by almost 50 percent. Much of this is attributed 

to the many tributaries that drain to Monument Creek, with 

median normal and stormflow discharge at the measured 

tributary sites ranging from less than 1.0 to 5.3 ft3/s during 

normal flow to less than 1.0 to 22 ft3/s during stormflow. 

Fountain Creek discharge increased downstream from the 

confluence because of the combined discharge from Fountain 

Creek and Monument Creek. Discharge from two wastewater 

treatment-plants located downstream from site 07105500 

(FoCr_Nevada) also contributed to the overall increase in 

discharge to Fountain Creek. During 1998 through 2006, 

median normal flow increased by 200 percent between sites 

07105500 (FoCr_Nevada) and 07105530 (FoCr_Janitell) 

because of discharge from the Las Vegas Street Wastewater 

Treatment Plant (fig. 3A; fig. 1). Sand Creek enters Fountain 

Creek downstream from site 07105530 (FoCr_Janitell), and 

14  Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Figure 2. Annual precipitation at the Colorado Springs Weather Service Office, (A) 1949 

through 2006, and (B) 1981 through 2006.

1950 1960 1970 1980 1990 2000

0

5

10

15

20

25

30

YEAR

1980 1985 1990 1995 2000 2005

ANNUAL PRECIPITATION, IN INCHES

0

5

10

15

20

25

30

ANNUAL PRECIPITATION, IN INCHES

A

B

Precipitation and Streamflow 15
Figure 3. Variations in sampled streamflow at (A) main-stem sites, and (B) tributary sites for base flow, normal flow, and 

stormflow in Fountain and Monument Creek watersheds, 1998 through 2006, and (C) comparison of sampled streamflow at 

selected main-stem sites between 1981 through 1997 and 1998 through 2006.

1981–1997 1998–2006

EXPLANATION

07103700

07103707

07103970

07104905

07105500

07105530

07105800

MAIN-STEM SITE

0.1

1.0

10

100

1,000

INSTANTANEOUS STREAMFLOW, 

IN CUBIC FEET PER SECOND

5,000

Upper Fountain Creek Monument Creek Lower Fountain Creek

TRIBUTARY SITE

0.01

0.1

1

10

100

1,000

385854104470100

07103960

385750104475001

07103977

07103985

07103990

07104050

385501104483701

385204104510101

385124104501301

07105000

384909104504401

07105600

INSTANTANEOUS STREAMFLOW, 

IN CUBIC FEET PER SECOND

Monument Creek Lower Fountain Creek

Base flow

Normal flow 

Stormflow

Outlier value

Outside value

75th percentile

Median

25th percentile

Smallest value within

1.5 times the IQR

Largest value within

1.5 times the IQR

Interquartile

Range (IQR)

A

B

EXPLANATION

Base flow

07103700

07104905

07105500

07105530

1

10

100

1,000

5,000

Normal flow

07103700

07104905

07105500

07105530

Stormflow

07103700

07104905

07105500

07105530

MAIN-STEM SITE

INSTANTANEOUS STREAMFLOW, 

IN CUBIC FEET PER SECOND

C

16 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
although median normal-flow discharges to Fountain Creek 

were small (3.0 ft3/s), median stormflow discharges were 

about 250 ft3/s and ranged from 5.5 to more than 1,000 ft3/s.

A comparison of flow conditions between 1981 

through 1997 and 1998 through 2006 at selected mainstem sites in upper Fountain Creek and Monument Creek, 

based on discharge measurements associated with waterquality sampling, indicated that base flow and normal flow 

discharge generally had not changed (fig. 3C). In Monument 

Creek, median stormflow discharge at site 07104905 

(MoCr_Bijou) increased from about 80 ft3/s to 105 ft3/s; 

the range of stormflow discharges was larger during 1998 

through 2006, ranging from 11 to 1,530 ft3/s compared to 46 

to 222 ft3/s during 1981 through 1997. The largest change 

in flow measurements between the two periods occurred at 

site 07105530 (FoCr_Janitell), where the increase in discharge 

is related to the Las Vegas Street Wastewater Treatment Plant. 

Discharges at site 07105530 (FoCr_Janitell) increased an 

average of about 20 percent during nonstormflow conditions 

and more than 160 percent during stormflow conditions 

between the two periods 1981 through 1997 and 1998 through 

2006 (fig. 3C).

Water Quality

The following sections of this report describe waterquality conditions in the Fountain and Monument Creek 

watersheds. Specifically, this section compares water-quality 

concentrations to selected land-use categories, compares 

water-quality concentrations to in-stream water-quality 

standards, compares water-quality concentrations for different 

flow regimes, compares water-quality concentrations between 

1981 through 1997 and 1998 through 2006, and finally, 

characterizes water-quality loads for selected constituents.

Relation of Water Quality to Land Use

Differing land uses and changes in land use can influence 

stream hydrology and water quality. Several land-use 

categories in the Fountain and Monument Creek watersheds, 

including agriculture, commercial, industrial, residential, 

streets and easements, airports and military reservations, 

and undeveloped lands, were investigated to determine if 

statistically significant relations could be identified between 

various water-quality constituents, physical properties, and 

land use in the Fountain and Monument Creek watersheds 

within the study area. Relations were evaluated using a 

Spearman’s rho correlation analysis (table 4). Streamflow was 

strongly correlated (r >0.8) with impervious area and for most 

land-use categories evaluated. Of the physical properties and 

water-quality constituents evaluated, only specific conductance 

and total phosphorus generally were indicated to have 

statistically significant correlation coefficients larger than 0.6. 

Other water-quality constituents (table 4) such as dissolved 

nitrite plus nitrate and dissolved ammonia were significantly 

correlated, but these constituents had correlation coefficients 

smaller than 0.6, indicating that less than 40 percent of the 

variation in water quality could be explained by variations in 

land use.

Comparison of Stormflow Water Quality to 

Colorado In-Stream Water-Quality Standards

In-stream water-quality standards have been established 

for stream segments in the Fountain and Monument Creek 

watersheds. Standards are based on stream classifications and 

the designated use of the stream segment as determined by 

the Colorado Department of Public Health and Environment 

(CDPHE) Water Quality Control Commission with public 

participation (Colorado Department of Public Health and 

Environment, 2006).

Numeric standards have been set for both fecal bacteria 

and Escherichia coli (E. coli) bacteria that are based on 

five-sample geometric means over a 30-day period. The 

water-quality standards for fecal coliform and E. coli are 

200 col/100 mL and 126 col/100 mL, respectively. This study 

did not collect sufficient bacteria samples for regulatory 

purposes; therefore, numeric standards based on geometric 

means do not apply in this report. The standard for E. coli

bacteria that was referenced in this report was based on the 

one-time primary contact standard of 235 col/100 mL and is 

statistically similar to the 126-col/100 mL standard based on 

the five-sample geometric means over a 30-day period (U.S. 

Environmental Protection Agency, 1986). During periods 

of normal flow and stormflow, E. coli exceeded the primary 

contact standard and will be discussed further in the report.

Standards for many constituents are fixed values; standards for other constituents, specifically for some trace 

elements, are calculated values that use mean hardness in 

determining the standard for each site. The mean hardness 

used in this report was calculated at each main-stem site by 

using the lower 95-percentile confidence interval for base-flow 

water-quality samples collected between November and March 

(Colorado Department of Public Health and Environment, 

2006). Standards have been established for 13 trace elements, 

depending on the stream reach, and most of the standards are 

applied to dissolved constituents (Colorado Department of 

Public Health and Environment, 2006). In this report, waterquality concentrations of trace elements from stormflow 

samples were compared to the acute standards. Specifically, 

the acute standard used in this report for total arsenic was 

50 μg/L and for dissolved selenium was 18.4 μg/L. The acute 

standards for dissolved copper and zinc varied by site and 

were based on mean base-flow hardness. The acute standard 

for dissolved copper ranged from 16.5 to 34.0 μg/L, and the 

acute standard for dissolved zinc ranged from 141 to 273 μg/L. 

The Colorado Department of Public Health and Environment 

(2001a, 2001b) defined acute standard as the level not to 

be exceeded by a concentration in a single sample or by an 

Water Quality 17
Table 4. Correlations between various land uses and physical properties and selected water-quality constituents for sites in the 

Fountain and Monument Creek watersheds, 1998 through 2005.

[Note: correlation coefficients that are statistically significant and are greater than 0.6 are shown in bold. R, Spearman correlation coefficients; p-value, 

probability value; Q, streamflow; P_TOT, total phosphorus; SC, specific conductance; NH4_D, dissolved ammonia; NO2NO3_D, dissolved nitrite plus 

nitrate; E_COL, Escherichia coli; FC_COL, fecal coliform; BOD, 5-day biochemical oxygen demand]

Total impervious area, in square miles

Q P_TOT SC NH4_D NO2NO3_D E_COL FC_COL

R 0.88 0.72 0.63 0.44 0.36 0.06 -0.04

p-value .0001 .0001 .0001 .0001 .0001 .10 .73

Total percent impervious area

Q P_TOT SC NH4_D NO2NO3_D E_COL BOD

R 0.86 0.72 0.64 0.44 0.40 0.07 0.05

p-value .0001 .0001 .0001 .0001 .0001 .06 .29

Agricultural area, in square miles

NO2NO3_D NH4_D P_TOT BOD E_COL SC FC_COL

R 0.58 0.188 0.15 0.14 0.12 0.10 0.04

p-value .0001 .0001 .0019 .0036 .0044 .0215 .97

Commercial area, in square miles

Q P_TOT SC NH4_D NO2NO3_D FC_COL E_COL

R 0.77 0.69 0.60 0.42 0.37 -0.07 0.06

p-value .0001 .0001 .0001 .0001 .0001 .61 .16

Industrial area, in square miles

Q P_TOT SC NH4_D NO2NO3_D E_COL BOD

R 0.85 0.65 0.56 0.43 0.38 0.08 0.02

p-value .0001 .0001 .0001 .0001 .0001 .04 .70

Residential area, in square miles

Q P_TOT SC NO2NO3_D NH4_D E_COL FC_COL

R 0.85 0.73 0.62 0.43 0.43 0.04 -0.04

p-value .0001 .0001 .0001 .0001 .0001 .34 .78

Undeveloped area, in square miles

Q P_TOT SC NH4_D NO2NO3_D E_COL BOD

R 0.84 0.73 0.64 0.44 0.39 0.08 0.06

p-value .0001 .0001 .0001 .0001 .0001 .04 .22

18 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
average calculated from all samples collected during a 1-day 

period.

Onsite Measurements of Specific Conductance, 

pH, and Dissolved Oxygen

Specific conductance, pH, and dissolved oxygen were 

measured onsite concurrently with sample collection. Variations in specific conductance, pH, and dissolved oxygen with 

respect to base flow, normal flow, and stormflow are shown in 

figures 4 and 5.

Specific Conductance

Specific conductance, which is an indicator of dissolved 

solids, generally decreased as streamflow increased. In 

general, the largest specific-conductance values occurred 

during base flow and, as a result of dilution, they were smaller 

during stormflow (fig. 4). Spatially, specific conductance 

tended to increase in a downstream direction. The largest 

spatial specific-conductance increases occurred during base 

flow and normal flow between Fountain Creek sites 07103700 

(FoCr_Manitou) and 07103707 (FoCr_8th), upstream from the 

confluence with Monument Creek, which indicates a relatively 

large source of dissolved solids (fig. 4A). This increase also 

is a reflection of the reduced streamflow at site 07103707 

(FoCr_8th); median streamflow during normal-flow conditions 

for the period 1998 through 2006 decreased from 15 ft3/s at 

site 07103700 (FoCr_Manitou) to 3 ft3/s at site 07103707 

(FoCr_8th), a result of streamflow diversions that occur 

between the two sites. Specific conductance in Monument 

Creek and the tributaries draining to it ranged from less than 

100 to more than 2,000 μS/cm during base-flow and normalflow conditions. Median specific-conductance concentrations 

for base-flow and normal-flow conditions generally ranged 

from 400 to 700 μS/cm, with the exception of two tributary 

sites, 07103985 (TbCo) and 07104050 (RkCr), tributaries 

to Cottonwood Creek and Monument Creek, respectively 

(fig. 4B). Site 07103985 (TbCo), a tributary to Cottonwood 

Creek, generally had specific-conductance values larger 

than 1,000 μS/cm during base flow and normal flow, which 

generally were 50 percent larger than values measured at 

other sites. Median specific-conductance concentrations 

at site 07104050 (RkCr) were 2 to 4 times larger than 

concentrations at most other tributaries, but the elevated 

concentrations probably are a result of the concentrating 

effects of low flows. Median flow at site 07104050 (RkCr) 

during normal flow was 0.07 ft3/s and generally was less 

than 0.1 ft3/s. One other tributary site, 07105600 (SaCr), had 

elevated specific-conductance values compared to other sites 

in the watershed. The median specific-conductance value 

during normal flow was 1,250 μS/cm at site 07105600 (SaCr). 

Although specific-conductance values are relatively high in 

Sand Creek above the mouth, median discharge measured 

at this location was 3.0 ft3/s during normal flow compared 

to about 100 ft3/s in Fountain Creek near the confluence 

with Sand Creek; therefore, the overall effect of specific 

conductance in Sand Creek to Fountain Creek is small.

pH and Dissolved Oxygen

During 1998 through 2006, median values of pH 

generally ranged from about 7.8 to 8.4; pH values measured 

during stormflows generally were smaller than during base 

flows and normal flows (fig. 5A). However, all measurements 

were well within the acceptable range for the in-stream 

standard for pH. The Colorado in-stream water-quality 

standard range for pH is 6.5 to 9.0.

Median dissolved-oxygen concentrations were 

consistently larger during base-flow conditions because 

the colder water temperatures that occur during the winter 

months allow more oxygen to stay in solution. Dissolvedoxygen concentrations generally were larger than 6 mg/L 

and were similar for normal flow and stormflow at most 

sites (fig. 5B). Another analysis used to measure oxygen 

content in water is percent saturation of dissolved oxygen; 

it is a measure of the amount of oxygen dissolved in water 

compared to the maximum amount that could be present at the 

same temperature and is determined from dissolved-oxygen 

concentrations, water temperature, and barometric pressure. 

At all main-stem and tributary sites in Fountain and 

Monument Creeks, percent saturation of dissolved oxygen 

generally was larger than 90 percent during all flow 

conditions, which indicated well-oxygenated streams (fig. 5C). 

The one exception occurred at Sand Creek, site 07105600 

(SaCr), during normal-flow conditions. The percent saturation 

of dissolved oxygen at this site ranged from 65 to 94 percent 

and the median value was 80 percent.

Biochemical Oxygen Demand

Biochemical oxygen demand measures the concentration 

of biodegradable organic matter present in a sample of water. 

It can be used to infer the general quality of the water and its 

degree of pollution by biodegradable organic matter. BOD 

is an indicator of the quality of a water body and commonly 

is measured over a 5-day period and referred to as BOD5. 

There is no in-stream water-quality standard for BOD5 in the 

Fountain and Monument Creek watersheds. However, typical 

BOD5 values for pristine rivers generally are less than 1 mg/L, 

and typical BOD5 values from three-stage treated municipal 

sewage is about 20 mg/L (Shelton, 1991).

Biochemical Oxygen Demand Concentrations 

during 1998 through 2006

BOD5 samples, as previously stated, were collected only 

at main-stem sites. BOD5 concentrations at all main-stem 

sites during 1998 through 2006 generally were larger during 

stormflow than during base flow and normal flow (fig. 6A). 

Water Quality 19
Figure 4. Variations in specific conductance at (A) main-stem sites and (B) tributary sites for base 

flow, normal flow, and stormflow in Fountain and Monument Creek watersheds, 1998 through 2006.

TRIBUTARY SITE

0

500

1,000

1,500

2,000

2,500

SPECIFIC CONDUCTANCE, 

IN MICROSIEMENS PER CENTIMETER

Upper Fountain Creek Monument Creek Lower Fountain Creek

07103700

07103707

07103970

07104905

07105500

07105530

07105800

07103980

0

500

1,000

1,500

2,000

2,500

SPECIFIC CONDUCTANCE, 

IN MICROSIEMENS PER CENTIMETER

Monument Creek Lower Fountain Creek

385854104470100

07103960

385750104475001

07103977

07103985

07103990

07104050

385501104483701

385204104510101

385124104501301

07105000

384909104504401

07105600

MAIN-STEM SITE

A

B

Base flow

Normal flow

Stormflow

Outlier value

Outside value

75th percentile

Median

25th percentile

Smallest value within

1.5 times the IQR

Largest value within

1.5 times the IQR

Interquartile Range (IQR)

EXPLANATION

20 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Figure 5. Variations in (A) pH, (B) dissolved oxygen concentrations, and (C) percent saturation of dissolved oxygen at main-stem sites 

and Sand Creek for base flow, normal flow, and stormflow in Fountain and Monument Creek watersheds, 1998 through 2006.

07103700

07103707

07103970

07104905

07105500

07105530

07105800

7.0

7.5

8.0

8.5

9.0

pH, IN STANDARD UNITS

Upper Fountain Creek Monument Creek Lower Fountain Creek

MAIN-STEM SITE

Upper Fountain

Creek

Monument

Creek

Lower Fountain

Creek

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

4

5

6

7

8

9

10

11

12

13

DISSOLVED OXYGEN, IN MILLIGRAMS PER LITER

Upper Fountain

Creek

Monument

Creek

Lower Fountain

Creek

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

MAIN-STEM SITES AND SAND CREEK

60

70

80

90

100

110

120

130

140

DISSOLVED OXYGEN, IN PERCENT SATURATION

Base flow

Normal flow 

Stormflow

Outlier value

Outside value

75th percentile

Median

25th percentile

Smallest value within

1.5 times the IQR

Largest value within

1.5 times the IQR

Interquartile

Range (IQR)

MAIN-STEM SITES AND SAND CREEK

A

B C

EXPLANATION

Water Quality 21
Median BOD5

 concentrations during stormflow ranged from 

1.0 to 10.3 mg/L compared with a range of 1.0 to 5.9 mg/L 

during base flow. BOD5 concentrations in upper Fountain 

Creek, upstream from the Fountain–Monument Creek confluence, generally were similar to concentrations in Monument 

Creek (fig. 6A). Downstream from the confluence of Fountain 

and Monument Creeks the range of BOD5 concentrations were 

larger: concentrations ranged from 1.0 to 17 mg/L during 

base-flow and normal-flow conditions to between 1.0 and 

26 mg/L during stormflow conditions. BOD5 concentrations 

tended to increase more at downstream sites 07105530 

(FoCr_Janitell) and 07105800 (FoCr_Security), both located 

downstream from wastewater treatment-plant effluents, than 

at other main-stem sites during base flow and normal flow. 

Median base-flow and normal-flow concentrations at these 

two sites, 07105530 (FoCr_Janitell) and 07105800 

(FoCr_Security), were similar. BOD5 concentrations measured 

during stormflow at site 07105800 (FoCr_Security) generally 

were larger than site 07105530 (FoCr_Janitell), indicating 

either additional sources of organic matter during stormflow or 

organically enriched streambed sediments were resuspended 

during stormflow. Median stormflow BOD5 concentrations at 

site 07105530 (FoCr_Janitell) and site 07105800 

(FoCr_Security) were 4.0 and 10.3 mg/L, respectively.

Comparison of Biochemical Oxygen Demand 

Concentrations between 1981 through 1997 and 

1998 through 2006

Differences in BOD5 concentrations between 1981 

through 1997 and 1998 through 2006 were evaluated at 

selected main-stem sites using a Kruskal-Wallis test to 

determine if the differences were statistically significant. 

Significant differences in BOD5 concentrations were evident 

at sites in Fountain Creek, both upstream and downstream 

from the confluence with Monument Creek. Two sites, 

07103700 (FoCr_Manitou) and 07105530 (FoCr_Janitell), 

showed significant differences in BOD5 between 1981 

through 1997 and 1998 through 2006 under all flow regimes. 

Median concentrations of BOD5 at 07103700 (FoCr_Manitou) 

increased slightly between the two time periods during base 

flow and normal flow to 1.0 mg/L; however, median stormflow 

concentrations increased between the two time periods from 

0.9 to 3.4 mg/L (fig. 6B). A potential cause of this increase 

could be associated with human population growth and 

associated organic material that occurs as overland runoff to 

Fountain Creek.

Median BOD5 concentrations at site 07105530 

(FoCr_Janitell) decreased significantly during all flow regimes 

between 1981 through 1997 and 1998 through 2006, and the 

range of concentrations also significantly decreased, including 

maximum and minimum concentrations. Between the two 

periods, median BOD5 concentrations at site 07105530 

(FoCr_Janitell) during normal and stormflow conditions 

decreased 84 percent, from 12.5 to 2.0 mg/L, and 62 percent, 

from 10.5 to 4.0 mg/L, respectively. Changes in BOD5 

concentration at site 07105530 (FoCr_Janitell) occurred in 

the early 1990s, and improvements to water quality are the 

result of treatment improvements made to the Las Vegas 

Street Wastewater Treatment Plant located upstream from 

site 07105530 (FoCr_Janitell) (fig. 6C).

Bacteria

Fecal coliform and E. coli were analyzed in streamflow 

samples. These bacteria are “indicator bacteria,” which are 

used to represent a potential for pathogenicity of surface water. 

Although these bacteria generally are not toxic themselves, 

they are used to represent all viruses, protozoa, and pathogenic 

bacteria that may cause illnesses associated with water contact 

and ingestion (U.S. Environmental Protection Agency, 2004).

Fecal Coliform Bacteria during 1998 through 2006

Fecal coliform bacteria concentrations, during 1998 

through 2006, were highly variable, generally varying by 

more than a factor of 10 between flow regimes at each site 

(fig. 7). Fecal coliform concentrations tended to be largest 

during stormflow and smallest during base flow. With 

the exception of site 07103707 (FoCr_8th) on Fountain 

Creek and site 07103970 (MoCr_Woodmen) on Monument 

Creek, median fecal coliform concentrations at all sites 

along the main-stem during periods of normal flow and 

stormflow were larger than 200 col/100 mL (fig. 7A). At all 

Fountain and Monument Creek sites, with the exception of 

07103707 (FoCr_8th) on Fountain Creek, the median fecal 

coliform concentrations during stormflow were larger than 

1,000 col/100 mL, whereas during base-flow conditions the 

median fecal coliform concentrations at most main-stem sites 

in the watershed, with the exception of site 07105530 (FoCr_

Janitell) in Fountain Creek, generally were smaller than 

100 col/100 mL.

Although the sample size is relatively small for the 

tributaries during stormflow, with the exception of the Bear 

Creek site 07105000 (upper_BeCr), median stormflow 

fecal coliform concentrations in tributaries were larger than 

1,000 col/100 mL (fig. 7B). Two sites on Kettle Creek, 

a tributary to Monument Creek, sites 385854104470100 

(upper_KeCr) and 07103960 (lower_KeCr), had median 

fecal coliform stormflow concentrations of 9,500 and 

7,100 col/100 mL, respectively, and concentrations ranged 

from about 300 to 140,000 col/100 mL. The area around Kettle 

Creek is mostly agricultural; cattle manure has been observed 

in the creek, possibly accounting for the high concentrations. 

Median fecal coliform concentrations were elevated, 

exceeding 10,000 col/100 mL, at three other Monument Creek 

tributary sites during periods of stormflow from 1998 through 

2006: sites 385750104475001 (PiCr), 07104050 (RkCr), and 

385124104501301 (lower_MeCr) (fig. 7B).

22 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Figure 6. Variations in 5-day biochemical oxygen demand (BOD5

) for base flow, normal flow, and stormflow at (A) main-stem sites in 

Fountain and Monument Creek watersheds, 1998 through 2006, (B) a comparison of BOD5 concentrations between 1981 through 1997 

and 1998 through 2006, and (C) temporal variations in 5-day biochemical oxygen demand (BOD5) at site 07105530.

1981–1997 1998–2006

EXPLANATION

1981

1983

1985

1987

1989

1991

1993

1995

1997

1999

2001

2003

2005

2007

YEAR

0

5

10

15

20

25

30

35

40

FIVE-DAY BIOCHEMICAL OXYGEN DEMAND, 

IN MILLIGRAMS PER LITER

Site 07105530

Base flow

Normal flow 

Stormflow

Outlier value

Outside value

75th percentile

Median

25th percentile

Smallest value within

1.5 times the IQR

Largest value within

1.5 times the IQR

Interquartile

Range (IQR)

MAIN-STEM SITE

07103700

07103707

07103970

07104905

07105500

07105530

07105800

0

5

10

15

20

25

30

FIVE-DAY BIOCHEMICAL OXYGEN DEMAND,

 IN MILLIGRAMS PER LITER

Upper Fountain Creek Monument Creek Lower Fountain Creek

A

07103700

0710490507105500

07105530

0

5

10

15

20

25

30

35

40

FIVE-DAY BIOCHEMICAL OXYGEN 

DEMAND, IN MILLIGRAMS PER LITER

Base flow

07103700

07104905

07105500

07105530

MAIN-STEM SITE

Normal flow

07103700

07104905

07105500

07105530

B Stormflow

C

EXPLANATION

Water Quality 23
Figure 7. Variations in fecal coliform for base flow, normal flow, and stormflow at (A) main-stem sites, (B) tributary sites in Fountain 

and Monument Creek watersheds, 1998 through 2006, and (C) comparison of variations in fecal coliform between 1981 through 1997 and 

1998 through 2006.

07103700

07103707

07103970

07104905

07105500

07105530

07105800

1

10

100

1,000

10,000

100,000

FECAL COLIFORM BACTERIA, 

IN COLONIES PER 100 MILLILITERS

TRIBUTARY SITE

07103700

07104905

07105500

07105530

1

10

100

1,000

10,000

100,000

FECAL COLIFORM BACTERIA, 

IN COLONIES PER 100 MILLILITERS

07103700

07104905

07105500

07105530

MAIN-STEM SITE

Base flow Normal flow

07103700

07104905

07105500

07105530

Storm flow

1981–1997

1998–2006

EXPLANATION

Upper Fountain Creek Monument Creek Lower Fountain Creek

1

10

100

1,000

10,000

100,000

FECAL COLIFORM BACTERIA, 

IN COLONIES PER 100 MILLILITERS

Monument Creek Lower Fountain Creek

07103980

385854104470100

07103960

385750104475001

07103977

07103985

07103990

07104050

385501104483701

385204104510101

385124104501301

07105000

384909104504401

07105600

Base flow

Normal flow 

Stormflow

Outlier value

Outside value

75th percentile

Median

25th percentile

Smallest value within

1.5 times the IQR

Largest value within

1.5 times the IQR

Interquartile

Range (IQR)

A

B

C

MAIN-STEM SITE

EXPLANATION

24  Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Based on a small number of samples, fecal coliform 

concentrations during 1998 through 2006 also were elevated 

farther downstream on tributary site 07105600 (SaCr), on 

Sand Creek, where median concentrations during normal-flow 

and stormflow conditions were 270 and 14,500 col/100 mL, 

respectively. Sand Creek drains a portion of urbanized area 

in Colorado Springs, but it is unclear what the sources of the 

elevated fecal coliform concentrations were at this location.

Comparison of Fecal Coliform Concentrations 

between 1981 through 1997 and 1998 through 

2006

The Kruskal-Wallis statistical test was applied to the 

fecal coliform data to evaluate whether there were statistically 

significant differences in fecal coliform concentrations 

between 1981 through 1997 and 1998 through 2006 at selected 

main-stem sites (fig. 7C). Tributary sites were not sampled for 

fecal coliform prior to 1998 and, therefore, were not included 

in this analysis. Only one site in the watershed, 07105500 

(FoCr_Nevada), showed statistically significant differences in 

fecal coliform concentrations. During normal flow, measured 

fecal coliform concentrations significantly decreased, and 

during stormflow, measured fecal coliform concentrations 

significantly increased between the two periods. Median 

fecal coliform concentrations decreased from 525 to 

440 col/100 mL during normal flow and increased from 800 

to 1,900 col/100 mL during stormflow. The site is downstream 

from the confluence of Fountain and Monument Creeks, so 

identification of source areas is difficult.

Escherichia Coli (E. coli) Bacteria Concentrations

Bacteria sampling for E. coli began in 2002. Similarly 

to fecal coliform concentrations, E. coli concentrations at 

each site, during 2003 through 2006, generally differed by a 

factor of 10 or more during all flow conditions (fig. 8). The 

smallest concentrations of E. coli were detected during periods 

of base flow and were largest during periods of stormflow. 

Median E. coli concentrations at main-stem sites during 

base flow were less than 100 col/100 mL, whereas median 

E. coli concentrations during normal-flow and stormflow 

conditions were much larger, ranging between 80 and 660 

col/100 mL during normal-flow conditions and 1,300 to 

17,000 col/100 mL during stormflow conditions (fig. 8A). 

Median E. coli concentrations during normal-flow and 

stormflow conditions at several sites exceeded the one-time 

primary contact standard of 235 col/100 mL bacteria used by 

CDPHE for E. coli (U.S. Environmental Protection Agency, 

1986).

Escherichia Coli (E. coli) Bacteria Concentrations 

at Tributary Sites

Based on a small number of samples, E. coli

concentrations also exceeded the 235-col/100 mL standard 

at many tributary sites during periods of normal flow 

and stormflow (fig. 8B). Median concentrations at three 

sites on tributaries to Monument Creek were particularly 

elevated during normal-flow and stormflow conditions: 

site 385750104475001 (PiCr) on Pine Creek, site 07103977 

(upper_CoCr) on Cottonwood Creek, and site 07104050 

(RkCr) on North Rockrimmon Creek. Median normalflow concentrations were 715, 430, and 230 col/100 mL, 

respectively. The Pine Creek and Cottonwood Creek sites 

are located in rural areas where cattle and horses are present, 

and it is possible that manure may be a major source of the 

elevated E. coli concentrations. Site 07104050 (RkCr) on 

North Rockrimmon Creek is urbanized and, based on the few 

data sampled at this site, it is unclear what may be causing the 

increased E. coli concentrations. Farther downstream, median 

E. coli concentrations at Sand Creek at site 07105600 (SaCr) 

were elevated during both normal-flow and stormflow periods 

and, as with fecal coliform, it is unknown what specific 

sources caused the large concentrations.

Nitrogen and Phosphorus

Nitrogen and phosphorus samples were collected from 

seven main-stem sites between 1998 and 2006 and at 14 

tributary sites beginning in 2003 (figs. 9 and 10).

Dissolved Nitrite plus Nitrate

Concentrations of dissolved nitrite plus nitrate 

(hereinafter referred to as “nitrite plus nitrate”) were larger 

at two sites on Cottonwood Creek, a tributary to Monument 

Creek, than at other nearby sites: 07103985 (TbCo) and 

07103990 (lower_CoCr) (fig. 10). The in-stream water-quality 

standard for nitrate is 10 mg/L (Colorado Department of 

Public Health and Environment, 2006). During base-flow 

and normal-flow conditions, the median concentrations 

of nitrite plus nitrate at these two sites ranged from 5.1 to 

6.1 mg/L and were 4 to 7 times larger than concentrations at 

the nearest upstream site on Monument Creek, site 07103970 

(MoCr_Woodmen) (figs. 9 and 10). Median stormflow 

concentrations of nitrite plus nitrate ranged from 0.93 

to 2.6 mg/L at these two sites (figs. 9 and 10). Median 

streamflow at site 07103985 (TbCo) during normal-flow 

conditions was less than 1.0 ft3/s, but during stormflow periods 

it was measured as large as 84 ft3/s. The source of these larger 

nitrite plus nitrate concentrations has not been identified, 

Water Quality 25
Figure 8. Variations in Escherichia coli (E. coli) for base flow, normal flow, and stormflow at (A) main-stem sites, 

and (B) tributary sites in Fountain and Monument Creek watersheds, 1998 through 2006.

07103700

07103707

07103970

07104905

07105500

07105530

07105800

1

10

100

1,000

10,000

100,000

ESCHERICHIA COLI BACTERIA, 

IN COLONIES PER 100 MILLILITERS

Upper Fountain Creek Monument Creek Lower Fountain Creek

TRIBUTARY SITE

1

10

100

1,000

10,000

100,000

ESCHERICHIA COLI BACTERIA, 

IN COLONIES PER 100 MILLILITERS

Monument Creek Lower Fountain Creek

385854104470100

07103960

385750104475001

07103977

07103985

07103990

07104050

385501104483701

385204104510101

385124104501301

07105000

384909104504401

07105600

A

B

MAIN-STEM SITE

Base flow

Normal flow

Stormflow

Outlier value

Outside value

75th percentile

Median

25th percentile

Smallest value within

1.5 times the IQR

Largest value within

1.5 times the IQR

Interquartile Range (IQR)

EXPLANATION

26 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Figure 9. Variations in nitrogen and phosphorus concentrations at main-stem sites for base flow, normal flow, and 

stormflow in the Fountain and Monument Creek watersheds, 1998 through 2006.

07103700

07103707

07103970

07104905

07105500

07105530

07105800

1

2

3

4

5

6

DISSOLVED NITRITE PLUS NITRATE,

 IN MILLIGRAMS PER LITER

0

07103700

07103707

07103970

07104905

07105500

07105530

07105800

MAIN-STEM SITE

0.01

0.10

1.00

TOTAL PHOSPHORUS, IN MILLIGRAMS PER LITER

9.00

07103700

07103707

07103970

07104905

07105500

07105530

07105800

0.001

0.01

0.10

1.00

DISSOLVED AMMONIA, IN MILLIGRAMS PER LITER5.00

Upper

Fountain Creek

Monument

Creek

Lower Fountain

Creek

Upper

Fountain Creek

Monument

Creek

Lower Fountain

Creek

Base flow

Normal flow 

Stormflow

Outlier value

Outside value

75th percentile

Median

25th percentile

Smallest value within

1.5 times the IQR

Largest value within

1.5 times the IQR

Interquartile

Range (IQR)

MAIN-STEM SITE

EXPLANATION

Water Quality 27
Figure 10. Variations in nitrogen and phosphorus concentrations at tributary sites for base flow, normal flow, and 

stormflow in the Fountain and Monument Creek watersheds, 1998 through 2006.

0.01

0.1

1.0

DISSOLVED AMMONIA, IN MILLIGRAMS PER LITER

5.0

Monument Creek

Lower Fountain 

Creek

0.001

0.1

1.0

10.0

DISSOLVED NITRITE PLUS NITRATE, 

IN MILLIGRAMS PER LITER

0.02

30.0

Monument Creek

Lower Fountain 

Creek

0.1

1.0

10.0

TOTAL PHOSPHORUS, IN MILLIGRAMS PER LITER

0.02

07103980

385854104470100 07103960 385750104475001

07103977

07103985 07103990

07104050

385501104483701 385204104510101 385124104501301 07105000

384909104504401 07105600

TRIBUTARY SITE

Base flow

Normal flow 

Stormflow

Outlier value

Outside value

75th percentile

Median

25th percentile

Smallest value within

1.5 times the IQR

Largest value within

1.5 times the IQR

Interquartile

Range (IQR)

EXPLANATION

07103980

385854104470100 07103960 385750104475001

07103977

07103985 07103990

07104050

385501104483701 385204104510101 385124104501301 07105000

384909104504401 07105600

TRIBUTARY SITE

28 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
but the fact that all measurements had elevated nitrite plus 

nitrate concentrations indicates a constant source. Median 

normal-flow concentrations of nitrite plus nitrate at a tributary 

site to Monument Creek, site 07104050 (RkCr), also were 

large. Although a small number of samples were collected 

at this site, the median nitrite plus nitrate concentration was 

13.3 mg/L, and concentrations ranged from about 7.0 mg/L 

to about 22.0 mg/L. As previously mentioned, site 07104050 

is located in an urbanized area, and the cause of the elevated 

concentrations is unclear.

Total Phosphorus

Median total phosphorus concentrations in Fountain 

Creek, upstream from the Monument Creek confluence, 

tended to be larger during stormflow and smaller during 

base-flow and normal-flow conditions (fig. 9). Median total 

phosphorus concentrations during base-flow and normal-flow 

conditions at site 07103700 (FoCr_Manitou) were 0.04 mg/L 

compared to 1.44 mg/L during stormflow conditions—more 

than 30 times larger than during base flow and normal flow. 

At site 07103707 (FoCr_8th), downstream from site 07103700 

(FoCr_Manitou), median total phosphorus concentrations 

were much smaller and ranged from 0.04 to 0.06 mg/L 

depending on flow regime (fig. 9). Median total phosphorus 

concentrations at sites 07103970 (MoCr_Woodmen) and 

07104905 (MoCr_Bijou) during stormflow conditions were 

2.4 to 5.6 times larger than concentrations during base-flow 

and normal-flow conditions, respectively.

Effect of Wastewater Treatment Plants

Between sites 07105500 (FoCr_Nevada) and 07105530 

(FoCr_Janitell), during 1998 through 2006, median concentrations of dissolved nitrite plus nitrate, dissolved ammonia, 

and total phosphorus increased substantially downstream 

from the Las Vegas Street Wastewater Treatment Plant (fig. 1; 

fig. 9). The upstream to downstream increase was most 

pronounced during base flow and normal flow but also was 

evident during stormflow for all nutrients analyzed. Median 

nutrient concentrations continued to increase between sites 

07105530 (FoCr_Janitell) and 07105800 (FoCr_Security), 

downstream from the Security Wastewater Treatment Plant, 

during periods of base flow and normal flow. Median total 

phosphorus concentrations during stormflow increased almost 

80 percent, from 1.9 to 3.4 mg/L between these two sites 

(fig. 9).

Comparisons of Nitrogen and Phosphorus 

Concentrations between 1981 through 1997 and 

1998 through 2006

Comparisons of nutrient data between 1981 through 1997 

and 1998 through 2006 indicated that at certain sites nutrient 

concentrations were statistically different between 1981 

through 1997 and 1998 through 2006 (fig. 11). For instance, 

median nitrite plus nitrate concentrations significantly 

decreased for all flow regimes at site 07104905 (MoCr_Bijou) 

from 1981 through 1997 to 1998 through 2006. Significant 

decreases occurred in dissolved ammonia and total phosphorus 

concentrations for all flow regimes at site 07105530 

(FoCr_Janitell) from 1981 through 1997 to 1998 through 

2006. Median concentrations of dissolved ammonia decreased 

from 7.7 to 0.11 mg/L during base-flow conditions and 

from 5.5 to 0.06 mg/L during normal-flow conditions at 

site 07105530 (FoCr_Janitell). Similar results also were 

observed for total phosphorus. Median total phosphorus 

base-flow concentrations at site 07105530 (FoCr_Janitell) 

decreased from 5.1 to 0.52 mg/L (90-percent decrease) and 

from 4.4 to 0.27 mg/L (94-percent decrease) during normal 

flow, and the decreases at this site probably can be attributed 

to improvements in wastewater-treatment technology made to 

the Las Vegas Street Wastewater Treatment Plant.

Trace Elements

Trace elements are inorganic chemicals that usually occur 

in small amounts in nature. These include essential elements, 

such as zinc, potential essential elements such as manganese, 

and potentially toxic elements such as lead, which may also 

have some essential functions at low levels (World Health 

Organization, 1996). The trace elements analyzed for this 

report include total arsenic, dissolved boron, dissolved and 

total copper, total lead, total manganese, total nickel, dissolved 

and total selenium, and dissolved and total zinc.

Selenium is of concern in the Fountain Creek watershed 

because of its presence in both Fountain and Monument 

Creeks and the potential effects it may have on the aquatic 

environment. Selenium occurs naturally and is present in many 

sedimentary formations; however, it is commonly present 

in elevated amounts in marine formations of Tertiary and 

Cretaceous age and in soils derived from these formations 

(Seiler and others, 1999). Natural precipitation and irrigation 

water that infiltrates through these geologic formations and 

soils can oxidize selenium to soluble selenate (SeO4

2–) and, 

under proper hydrologic conditions, the mobilized selenium 

can be transported through irrigation drains and shallow 

ground-water movement and discharged to wildlife areas such 

as ponds, lakes, streams, and wetlands. In arid climates and 

terminal drainage basins, evaporation and transpiration can 

concentrate selenium in natural waters to toxic concentrations 

(Rowland and others, 2003).

Several dissolved trace-element concentrations associated 

with stormflow during 1998 through 2006 decreased or 

showed little change compared to base flow (fig. 12). Median 

stormflow concentrations of dissolved boron, dissolved 

copper, dissolved and total selenium, and dissolved zinc 

generally were smaller than base-flow and normal-flow 

concentrations. Median concentrations of total copper, lead, 

Water Quality 29
Figure 11. Variations in nitrite plus nitrate, ammonia, and phosphorus concentrations at selected sites between 1981 through 

1997 and 1998 through 2006 for base flow, normal flow, and stormflow in the Fountain and Monument Creek watersheds. DISSOLVED NITRITE PLUS NITRATE, IN MILLIGRAMS PER LITER

1.0

10

0.5

Base flow Normal flow Stormflow

0.001

0.01

0.1

1.0

10

DISSOLVED AMMONIA, 

IN MILLIGRAMS PER LITER

Base flow Normal flow Stormflow

TOTAL PHOSPHORUS, 

IN MILLIGRAMS PER LITER

0.1

1.0

10

Base flow Normal flow Stormflow

0.05

1998–2006

1981–1997

Outlier value

Outside value

75th percentile

Median

25th percentile

Smallest value within

1.5 times the IQR

Largest value within

1.5 times the IQR

Interquartile Range (IQR)

07103700

07104905

07105500

07105530

07103700

07104905

07105500

07105530

MAIN-STEM SITE

07103700

07104905

07105500

07105530

EXPLANATION

30 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Figure 12. Variations in arsenic, boron, copper, lead, and manganese at main-stem sites for base flow, normal flow, and stormflow 

in the Fountain and Monument Creek watersheds, 1998 through 2006.

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

50

100

150

200

250

300

DISSOLVED BORON, 

IN MICROGRAMS PER LITER

10

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

1.0

 10

100

TOTAL COPPER, 

IN MICROGRAMS PER LITER

300

DISSOLVED COPPER, 

IN MICROGRAMS PER LITER

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

1.0

10

100

300

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

10

100

1,000

TOTAL MANGANESE, 

IN MICROGRAMS PER LITER

8,000

MAIN-STEM SITE MAIN-STEM SITE

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

0.1

1.0

10

100

TOTAL LEAD, IN MICROGRAMS PER LITER

700

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

1.0

10.0

100

TOTAL ARSENIC, 

IN MICROGRAMS PER LITER

300

range in analytical

 reporting limit

Upper

Fountain

Creek

Lower

Fountain

Creek

Monument

Creek

Upper

Fountain

Creek

Lower

Fountain

Creek

Monument

Creek

Base flow

Normal flow 

Stormflow

Outlier value

Outside value

75th percentile

Median

25th percentile

Smallest value within

1.5 times the IQR

Largest value within

1.5 times the IQR

Interquartile

Range (IQR)

EXPLANATION

Water Quality  31
Figure 13. Variations in nickel, selenium and zinc at main-stem sites for base flow, normal flow, and 

stormflow in the Fountain and Monument Creek watersheds, 1998 through 2006.

0

5

10

15

20

TOTAL SELENIUM, 

IN MICROGRAMS PER LITER

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

0

5

10

15

20

DISSOLVED SELENIUM, 

IN MICROGRAMS PER LITER

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

MAIN-STEM SITE

10

100

1,000

TOTAL ZINC, IN MICROGRAMS PER LITER

 2

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

MAIN-STEM SITE

1

10

100

1,000

DISSOLVED ZINC, IN MICROGRAMS PER LITER

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

1.0

10

100

TOTAL NICKEL,

 IN MICROGRAMS PER LITER

0.4

Upper

Fountain

Creek

Lower Fountain

Creek

Monument

Creek

Upper

Fountain

Creek

Monument

Creek

Lower Fountain

Creek

Base flow

Normal flow 

Stormflow

Outlier value

Outside value

75th percentile

Median

25th percentile

Smallest value within

1.5 times the IQR

Largest value within

1.5 times the IQR

Interquartile

Range (IQR)

EXPLANATION

32 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
manganese, nickel, and zinc for stormflow samples generally 

were much larger than nonstormflow samples (figs. 12 and 

13). However, concentrations of the dissolved phase of these 

trace elements were low during stormflow, indicating that 

these trace elements are transported in the particulate phase 

and are sorbed to sediments during stormflow.

Main-Stem Trace-Element Concentrations from 

1998 through 2006

Large differences in median base-flow concentration in 

several trace elements were apparent between Fountain Creek 

sites 07103700 (FoCr_Manitou) and 07103707 (FoCr_8th), 

upstream from the confluence with Monument Creek. 

Concentrations of dissolved and total copper, total manganese, 

total nickel, dissolved and total selenium, and dissolved and 

total zinc ranged from 3 to 27 times larger at site 07103707 

(FoCr_8th) than site 07103700 (FoCr_Manitou) during base 

flow, indicating a large source of trace elements between these 

two sites (figs. 12 and 13). The acute in-stream water-quality 

standard for dissolved zinc, based on base-flow conditions, 

was exceeded three times during 1998 through 2006. There 

were no other trace-element water-quality exceedances at this 

site or any other sites in the watershed. Median total selenium 

concentrations during base flow and normal flow increased 

from 1.0 to 6.8 micrograms per liter (μg/L) and 0.50 to 

4.0 μg/L, respectively, between sites 07103700 

(FoCr_Manitou) and 07103707 (FoCr_8th). The likely 

source area is Gold Hill Mesa, a former tailings pile for a 

gold refinery located just upstream from the confluence with 

Monument Creek, and upstream from site 07103707 

(FoCr_8th). Gold Hill Mesa currently (2007) is being 

developed under an approved VCUP (Colorado Voluntary 

Cleanup Program) plan (Colorado Department of Public 

Health and Environment, 2003). The VCUP plan is a 

process authorized by the State of Colorado and the USEPA 

to have landowners create a plan that would mitigate 

the environmental concerns for a property with known 

contaminants (L. Ross, Colorado Springs City Engineering, 

written commun., 2007). There also have been channel 

changes made to Fountain Creek in the vicinity of Gold Hill 

Mesa that may have disturbed stream sediments, resulting in 

periodic downstream transport of sediment and trace elements. 

As previously mentioned, streamflow from Fountain Creek is 

diverted downstream from site 07103700 (FoCr_Manitou) and 

upstream from Gold Hill Mesa, causing a reduction in flow; 

the median normal flow decreased from 15.0 ft3/s to 3.2 ft3/s, 

and the result of this diversion reduces the dilution capacity 

for dissolved trace elements.

Concentrations of several trace elements increased 

upstream to downstream during 1998 through 2006 between 

upper Monument Creek at site 07103970 (MoCr_Woodmen) 

and lower Monument Creek at site 07104905 (MoCr_Bijou) 

and continued to increase in Fountain Creek downstream from 

the confluence with Monument Creek (figs. 12 and 13). These 

trends were statistically significant for total arsenic, dissolved 

boron, dissolved and total copper, total lead, total nickel, and 

dissolved and total selenium. Median concentrations of total 

copper, total lead, and total nickel concentrations more than 

doubled during periods of base flow between Monument 

Creek at site 07103970 (MoCr_Woodmen) and lower 

Monument Creek at site 07104905 (MoCr_Bijou), and median 

concentrations of dissolved and total selenium increased by 3 

to 5 times between the same two sites during periods of base 

flow and normal flow. These increases could be attributed to a 

combination of geologic influences from the streambed along 

with the contribution from urban runoff. Peak dissolved and 

total selenium concentrations occurred in 2001 and have been 

declining in recent years.

Farther downstream in Fountain Creek, stormflow 

concentrations for total copper, lead, manganese, nickel, 

and zinc were larger at site 07105800 (FoCr_Security) than 

07105530 (FoCr_Janitell), compared with other main-stem 

sites, and indicate a relatively large source of these metals 

between the two sites (figs. 12 and 13). Similar patterns for 

total copper, lead, nickel, and zinc were observed during 

the previous permit period, 1998 through 2002 (Edelmann 

and others, 2002), indicating that the source area is still 

contributing trace metals downstream from site 07105530 

(FoCr_Janitell), although in some cases median stormflow 

concentrations have declined slightly since 1998.

Sand Creek Trace-Element Concentrations from 

2003 through 2006

Total concentrations of selected trace elements were 

sampled, beginning in 2003, at tributary site 07105600 

(SaCr) (figs. 12 and 13). The site is located downstream 

from Fountain Creek site 07105530 (FoCr_Janitell). 

During stormflow, concentrations of total arsenic, copper, 

manganese, nickel, and zinc were 20 to 1,000 percent larger at 

site 07105600 (SaCr) than at site 07105530 (FoCr_Janitell), 

with the largest differences occurring for total manganese; 

median stormflow concentrations of total manganese increased 

from 477 μg/L at site 07105530 (FoCr_Janitell) to 1,725 μg/L 

at site 07105600 (SaCr). The elevated median trace-element 

concentrations from Sand Creek may be a large contributing 

factor to the elevated concentrations at downstream 

site 07105800 (FoCr_Security), although there may be other 

unidentified source areas. Also, as previously mentioned, 

annual differences in streamflow observed temporal and 

spatial differences in constituent concentrations may be related 

to temporal differences in streamflow.

Water Quality  33
Comparisons of Trace-Element Concentrations 

between 1981 through 1997 and 1998 through 

2006

Trace-element concentrations from 1981 through 1997 

were compared to concentrations from 1998 through 2006 to 

determine whether trace-element concentrations had increased 

or decreased over time (figs. 14 and 15). Differences in 

measured streamflow between the two periods may partially 

explain some of the observed differences in trace-element 

concentrations. A Kruskal-Wallis test was applied to selected 

trace elements at sites where sufficient data were available 

from 1981 to 2006, and the test showed that there was a 

statistically significant decrease between 1981 through 1997 

and 1998 through 2006 in total lead concentrations during 

base-flow and normal-flow conditions at most main-stem sites, 

but an increase in stormflow concentrations was noted over the 

same period. Statistically significant differences between 1981 

through 1997 and 1998 through 2006 occurred at individual 

main-stem sites for trace elements such as copper, manganese, 

nickel, and zinc. The differences were especially significant at 

upper Fountain Creek site 07103700 (FoCr_Manitou) for total 

copper, total nickel, and total zinc during stormflow. Some of 

the differences in concentrations may be a result of differences 

in the magnitude of storms sampled between the two periods 

rather than temporal differences between the two periods. 

Median concentrations of total copper increased from 4 μg/L 

during 1981 through 1997 to 37 μg/L during 1998 through 

2006. Similarly, median total nickel concentrations increased 

from 1.0 to 20 μg/L and median total zinc concentrations 

increased from 30 to 320 μg/L between 1981 through 1997 

and 1998 through 2006, respectively. Total selenium concentrations also increased at most sites during the same period, 

and the increase was statistically significant for all flow 

regimes at site 07105500 (FoCr_Nevada).

Comparison of Loads during Stormflow and 

Base-Flow and Normal-Flow Conditions

Instantaneous loads in this report were computed by 

multiplying concen­tration data by streamflow and an appropriate conversion factor. Instantaneous loads provide an 

estimate of the mass of a constituent transported past a given 

site during a given time and were expressed in pounds per 

day (lb/d). In contrast to concentration data, instantaneous 

load calculations provide a perspective on the mass transport 

of water-quality constituents and are useful in estimating 

the amount of nonpoint and point sources contributing to 

water-quality contamination. However, the instantaneous 

loads presented were based on a small data set and may not 

represent the range in loads that occurred in the watershed.

Loads vary considerably as a result of changes in 

streamflow, constituent concentrations, or both. Large 

constituent loads occur in response to snowmelt and storms. 

Median streamflows associated with stormflow samples that 

were collected generally were between 3 to 5 times larger 

than base-flow and normal-flow streamflows for Fountain 

Creek upstream from Monument Creek, 5 to 6 times larger for 

Monument Creek, and 3 to 5 times larger for Fountain Creek 

downstream from Monument Creek (fig. 3). Instantaneous 

loads for base flows, normal flows, and stormflows were 

computed for nutrients and trace elements to characterize the 

relative quantity of these constituents transported in Fountain 

and Monument Creeks. Also, as described in an earlier section 

of this report, median base flow, normal flow, and stormflow 

generally were smaller at selected main-stem sites during 

1981 through 1997 than 1998 through 2006; therefore, loads 

generally were smaller during 1981 through 1997 than 1998 

through 2006.

Nitrogen and Phosphorus Loads

Main-Stem Nitrogen and Phosphorus Loads

Instantaneous nutrient loads varied considerably from 

site to site during 1998 through 2006, and stormflow loads 

generally were considerably larger than base-flow and 

normal-flow loads (figs. 16 and 17). In Fountain Creek 

upstream from the confluence with Monument Creek at 

site 07103700 (FoCr_Manitou), median dissolved ammonia 

loads ranged from about 0.7 lb/d during normal flow to about 

16 lb/d during stormflow. Median total phosphorus loads 

at the same location ranged from less than 4.0 lb/d during 

normal flow to 275 lb/d during stormflow, almost 70 times 

larger during stormflow. In Monument Creek at site 07103970 

(MoCr_Woodmen), median nitrite plus nitrate loads increased 

from about 90 lb/d during normal flow to more than 250 lb/d 

during stormflow. Median total phosphorus loads increased 

from less than 20 lb/d during normal flow to more than 

260 lb/d during stormflow.

Loads increased downstream from the Fountain–

Monument Creek confluence primarily because of the 

combined flows from both creeks, but also, in some cases, 

because nutrient concentrations were larger in lower Fountain 

Creek, downstream from the confluence, than in upper 

Fountain or Monument Creeks. Large increases in nutrient 

loading were particularly noticeable downstream from the Las 

Vegas Street Wastewater Treatment Plant, at site 07105530 

(FoCr_Janitell). Nutrient loads increased, on average, more 

than 350 percent during stormflow between sites 07105500 

(FoCr_Nevada), upstream from the plant and 07105530 

(FoCr_Janitell), downstream from the plant (fig. 16).

Tributary Nitrogen and Phosphorus Loads

Tributaries contributed a large amount of the total nutrient 

load estimated at main-stem sites on Monument Creek during 

1998 through 2006 (fig. 17). The combined median stormload contributions from sites 07103960 (lower_KeCr) and 

385750104475001 (PiCr) to site 07103970 (MoCr_Woodmen) 

represented almost 30 to 60 percent of the total median load 

34  Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
1998–2006

1981–1997

EXPLANATION

Base flow Normal flow

07103700

0710490507105500

07105530

10

100

DISSOLVED BORON,

 IN MICROGRAMS PER LITER

500

07103700

07104905

07105500

07105530

07103700

0710490507105500

07105530

07103700

07104905

07105500

07105530

1

10

100

TOTAL COPPER, 

IN MICROGRAMS PER LITER

500

07103700

07104905

07105500

07105530

Base flow Normal flow Stormflow

07103700

07104905

07105500

07105530

Base flow

07103700

07104905

07105500

07105530

1

10

100

1,000

TOTAL MANGANESE, 

IN MICROGRAMS PER LITER

Normal flow

07103700

07104905

07105500

07105530

Stormflow

07103700

07104905

07105500

07105530

Stormflow

07103700

07104905

07105500

07105530

0.1

1.0

10

100

1,000

TOTAL LEAD, 

IN MICROGRAMS PER LITER

Base flow

07103700

07104905

07105500

07105530

Normal flow

07103700

07104905

07105500

07105530

Stormflow

Outlier value

Outside value

75th percentile

Median

25th percentile

Smallest value within

1.5 times the IQR

Largest value within

1.5 times the IQR

Figure 14. Variations in boron, copper, lead, and manganese Interquartile Range (IQR)

concentrations between 1981 through 1997 and 1998 through 2006 

at selected sites for base flow, normal flow, and stormflow in the 

Fountain and Monument Creek watersheds.

Water Quality  35
07103700

07104905

07105500

07105530

0

5

10

15

20

25

30

DISSOLVED SELENIUM, 

IN MICROGRAMS PER LITER

07103700

07104905

07105500

07105530

07103700

07104905

07105500

07105530

07103700

07104905

07105500

07105530

0

5

10

15

20

25

30

TOTAL SELENIUM, 

IN MICROGRAMS PER LITER

07103700

07104905

07105500

07105530

07103700

07104905

07105500

07105530

Base flow Normal flow Stormflow

Base flow Normal flow Stormflow

Base flow

07103700

0710490507105500

07105530

0

20

40

60

80

100

TOTAL NICKEL,

 IN MICROGRAMS PER LITER

Normal flow

07103700

0710490507105500

07105530

Stormflow

07103700

0710490507105500

07105530

MAIN-STEM SITE MAIN-STEM SITE MAIN-STEM SITE

07103700

07104905

07105500

07105530

1

10

100

1,000

TOTAL ZINC, 

IN MICROGRAMS PER LITER

Base flow

07103700

07104905

07105500

07105530

Normal flow

07103700

07104905

07105500

07105530

Stormflow

1998–2006

1981–1997

EXPLANATION

Outlier value

Outside value

75th percentile

Median

25th percentile

Smallest value within

1.5 times the IQR

Largest value within

1.5 times the IQR

Figure 15. Variations in nickel, selenium, and zinc concen- Interquartile Range (IQR)

trations between 1981 through 1997 and 1998 through 2006 

at selected main-stem sites for base flow, normal flow, and 

stormflow in the Fountain and Monument Creek watersheds.

36 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Figure 16. Variations in nitrogen and phosphorus loads at main-stem sites for base flow, normal flow, 

and stormflow in the Fountain and Monument Creek watersheds, 1998 through 2006.

07103700

07103707

07103970

07104905

07105500

07105530

07105800

MAIN-STEM SITE

0.1

1.0

10

100

1,000

10,000

100,000

TOTAL PHOSPHORUS LOAD, 

IN POUNDS PER DAY

0.1

1.0

10

100

1,000

DISSOLVED AMMONIA LOAD, 

IN POUNDS PER DAY

6,000

07103700

07103707

07103970

07104905

07105500

07105530

07105800

Upper

Fountain

 Creek

Monument

 Creek

Lower Fountain

 Creek

07103700

07103707

07103970

07104905

07105500

07105530

07105800

1

10

100

1,000

10,000

DISSOLVED NITRITE PLUS NITRATE LOAD, 

IN POUNDS PER DAY

30,000

Upper

Fountain

 Creek

Monument

 Creek

Lower Fountain

 Creek

Base flow

Normal flow 

Stormflow

Outlier value

Outside value

75th percentile

Median

25th percentile

Smallest value within

1.5 times the IQR

Largest value within

1.5 times the IQR

Interquartile

Range (IQR)

EXPLANATION

estimated at site 07103970 (MoCr_Woodmen), depending 

on the selected nutrient. The median streamflow contribution 

during stormflow from sites 07103960 (lower_KeCr) and 

385750104475001 (PiCr) represented about 30 percent of 

the total median flow to site 07103970 (MoCr_Woodmen). 

Similarly, storm-load contributions of dissolved ammonia and 

total phosphorus at site 07103990 (lower_CoCr) represented 

42 and 46 percent, respectively, of the total median loading 

estimated for these nutrients at site 07104905 (MoCr_Bijou).

Median streamflow during stormflow at Sand Creek 

site 07105600 (SaCr) was about 250 ft3/s and ranged from 

5 to 1,000 ft3/s; therefore, the potential nutrient loading to 

downstream Fountain Creek site 07105800 (FoCr_Security) 

could have been substantial. Nutrient loads were larger at 

site 07105800 (FoCr_Security) than at any other main-stem 

site for all flow regimes except for dissolved ammonia, 

which decreased by 50 percent during stormflow between 

sites 07105530 (FoCr_Janitell) and 07105800 (FoCr_Security) 

(fig. 16). The nutrient load increase at site 07105800 

(FoCr_Security) was not surprising because this site is the 

most downstream site in the study area and accumulates loads 

from throughout the watershed.

Water Quality  37
Figure 17. Variations in nitrogen and phosphorus loads at tributary sites for base flow, normal flow, and stormflow in the 

Fountain and Monument Creek watersheds, 1998 through 2006.

Monument Creek

0.01

0.1

1.0

10

100

DISSOLVED AMMONIA LOAD, 

IN POUNDS PER DAY

Lower

Fountain

Creek

0.001

400

07103980

0.001

0.01

0.1

1.0

10

100

1,000

10,000

TOTAL PHOSPHORUS LOAD, 

IN POUNDS PER DAY

30,000

385854104470100 07103960 385750104475001 07103977

07103985 07103990 07104050

385501104483701

385204104510101 385124104501301 07105000

384909104504401 07105600

Monument Creek

0.1

1.0

10

100

1,000

DISSOLVED NITRITE PLUS NITRATE LOAD, 

IN POUNDS PER DAY

0.01

Lower 

Fountain

Creek

TRIBUTARY SITE

Base flow

Normal flow 

Stormflow

Outlier value

Outside value

75th percentile

Median

25th percentile

Smallest value within

1.5 times the IQR

Largest value within

1.5 times the IQR

Interquartile

Range (IQR)

EXPLANATION

38 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
concentration data were not collected during 1998 through 

2006, but load contributions from tributaries could be 

considerable during stormflow and could account for some of 

the loads estimated at site 07104905 (MoCr_Bijou).

Trace-Element Loads in Fountain Creek Downstream from 

Confluence

Loads for most dissolved and total trace elements 

increased at Fountain Creek sites downstream from the 

confluence with Monument Creek (fig. 18). The increase 

corresponded to the increase in streamflow measured at sites 

07105500 (FoCr_Nevada), 07105530 (FoCr_Janitell), and 

07105800 (FoCr_Security). The median base flow and normal 

flow at site 07105530 (FoCr_Janitell) were 2 to 3 times larger 

than at site 07105500 (FoCr_Nevada), and the differences in 

streamflow between the two sites can be attributed to the Las 

Vegas Street Wastewater Treatment Plant. The difference, 

however, in selected trace-element loads was much larger 

than the differences in streamflow between the two sites. 

During normal-flow conditions, the median loads of dissolved 

boron, total copper, and total zinc were about 9 times larger 

at site 07105530 (FoCr_Janitell) than at site 07105500 

(FoCr_Nevada). Median dissolved zinc loads during normal 

flow increased from 0.7 to 19.0 lb/d between the two sites, 

a 2,600-percent increase that cannot be attributed solely to 

the increased streamflow. Zinc commonly is found in urban 

runoff and is directly correlated with street traffic volumes 

(University of Wisconsin–Extension, 1997) and may be contributing to the increase. At site 07105800 (FoCr_Security), 

the most downstream site for purposes of this report, traceelement loads generally were similar to or slightly larger than 

at site 07105530 (FoCr_Janitell) during base flow and normal 

flow. Median storm loads were 2 to 565 times larger than baseflow and normal-flow loads; total lead and total manganese 

increased by factors of 412 and 72, respectively, compared to 

normal flow.

Suspended Sediment

Suspended-sediment discharge is the mass of suspended 

sediment transported over time and, in this report, is expressed 

in tons per day (tons/d). Sediment discharge in a stream is 

the result of erosion and sediment-transport rates that occur 

throughout the watershed. Tributaries may discharge large 

volumes of sediment to a stream, and others may discharge 

small volumes. Additionally, in-channel processes erode 

banks, mobilize (scour) bed sediments, and deposit (fill) 

bed sediments. Eroded sediments can be transported by two 

modes: by rolling, bouncing, and sliding along the bed as 

“bedload,” or by being transported in the water column by 

turbulence as “suspended load.” Total sediment load is the 

sum of bedload and suspended load. Von Guerard (1989b) 

indicated that in Fountain and Monument Creeks, bedload 

represented about 6 to 30 percent of the total sediment load 

Trace-Element Loads

Trace-Element Loads in Upper Fountain Creek

Instantaneous loads for the period 1998 through 2006 

were calculated for dissolved boron, copper, selenium, and 

zinc and total arsenic, copper, lead, manganese, nickel, 

selenium, and zinc (figs. 18 and 19). Trace-element loads 

during base flow and normal flow generally were relatively 

small in Fountain Creek at sites 07103700 (FoCr_Manitou) 

and 07103707 (FoCr_8th), upstream from the confluence 

with Monument Creek. During base flow and normal flow, 

median loads were less than 5 lb/d for dissolved trace 

elements compared to stormflow loads that ranged from 4 

to 12 times larger. The differences in loads are largely due 

to the proportional streamflow increase during periods of 

stormflow. Median base-flow and normal-flow loads of total 

arsenic, copper, lead, nickel, and selenium were less than 

1 lb/d at sites 07103700 (FoCr_Manitou) and 07103707 

(FoCr_8th), and stormflow loads for these constituents 

were 6 to more than 1,400 times larger than base-flow and 

normal-flow loads. Median total manganese and zinc loads at 

site 07103707 (FoCr_8th) were about 2 to 4 times larger than 

at site 07103700 (FoCr_Manitou) during base flow and normal 

flow, but loads at both sites generally were less than 6 lb/d for 

each constituent. Median stormflow loads at site 07103700 

(FoCr_Manitou) for total manganese and zinc were 362 and 

60 lb/d, respectively, and were 112 to 319 times larger during 

stormflow than during base flow and normal flow.

Trace-Element Loads in Monument Creek Upstream from 

Confluence

Instantaneous loads were calculated for Monument 

Creek sites 07103970 (MoCr_Woodmen) and 07104905 

(MoCr_Bijou). Base-flow and normal-flow loads for most 

dissolved constituents were less than 1 lb/d but were 2 to 

8 times larger during stormflow. Median dissolved boron 

loads at site 07103970 (MoCr_Woodmen) ranged from 4.5 to 

6.6 lb/d during base-flow and normal-flow periods and were 

about 2 times larger during stormflow. Loads of total trace 

elements also increased between base flow, normal flow, and 

stormflow, and at site 07104905 (MoCr_Bijou), depending 

on the constituent, were 3 to 1,440 times larger during storm 

periods. At this site, the median storm load of total lead was 

72 lb/d compared to 0.05 lb/d or less during base-flow and 

normal-flow periods.

Loads of most dissolved and total trace elements 

increased between sites 07103970 (MoCr_Woodmen) and 

07104905 (MoCr_Bijou) during base flow, normal flow, and 

stormflow (fig. 18). The load increase generally was between 

2 and 4 times larger at the downstream site 07104905 

(MoCr_Bijou) during base flow and normal flow but was 

larger during stormflow when loads at site 07104905 

(MoCr_Bijou) increased by 1.2 to 18 times over loads at 

site 07103970 (MoCr_Woodmen). Trace-element loads 

were not estimated for Monument Creek tributaries because 

Suspended Sediment  39
Figure 18. Variations in streamflow, arsenic, boron, copper, and lead loads at main-stem sites for base flow, normal flow, and 

stormflow in the Fountain and Monument Creek watersheds, 1998 through 2006.

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

0.1

1.0

10

100

1,000

STREAMFLOW,

IN CUBIC FEET PER SECOND

5,000

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

0.01

0.1

1.0

10

100

1,000

TOTAL ARSENIC LOAD, 

IN POUNDS PER DAY

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

0.1

1.0

10

100

1,000

DISSOLVED BORON LOAD, 

IN POUNDS PER DAY

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

0.01

0.1

1.0

10

DISSOLVED COPPER LOAD, 

IN POUNDS PER DAY

60

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

MAIN-STEM SITE

0.01

0.1

1.0

10

100

1,000

TOTAL COPPER LOAD, 

IN POUNDS PER DAY

4,000

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

MAIN-STEM SITE

0.001

0.01

0.1

1.0

10

100

1,000

TOTAL LEAD LOAD, 

IN POUNDS PER DAY

6,000

Upper

Fountain

Creek

Lower

Fountain

Creek

Monument

Creek

Upper

Fountain

Creek

Lower

Fountain

Creek

Monument

Creek

Base flow

Normal flow 

Stormflow

Outlier value

Outside value

75th percentile

Median

25th percentile

Smallest value within

1.5 times the IQR

Largest value within

1.5 times the IQR

Interquartile

Range (IQR)

EXPLANATION

40 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Figure 19. Variations in manganese, nickel, selenium, and zinc loads at main-stem sites for base flow, normal flow, and stormflow in 

the Fountain and Monument Creek watersheds, 1998 through 2006.

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

0.1

1.0

10

100

1,000

10,000

100,000

TOTAL MANGANESE LOAD, 

IN POUNDS PER DAY

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

0.01

0.1

1.0

10

100

1,000

TOTAL NICKEL LOAD, 

IN POUNDS PER DAY

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

0.01

0.1

1.0

10

100

TOTAL SELENIUM LOAD, 

IN POUNDS PER DAY

300

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

0.01

0.1

1.0

10

100

DISSOLVED SELENIUM LOAD, 

IN POUNDS PER DAY

300

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

MAIN-STEM SITE

0.1

1.0

10

100

1,000

10,000

TOTAL ZINC LOAD, 

IN POUNDS PER DAY

MAIN-STEM SITE

07103700

07103707

07103970

07104905

07105500

07105530

07105600

07105800

0.1

1.0

10

100

1,000

10,000

DISSOLVED ZINC LOAD, 

IN POUNDS PER DAY

Upper

Fountain

Creek

Lower

Fountain

Creek

Monument

Creek

Upper

Fountain

Creek

Lower

Fountain

Creek

Monument

Creek

Base flow

Normal flow 

Stormflow

Outlier value

Outside value

75th percentile

Median

25th percentile

Smallest value within

1.5 times the IQR

Largest value within

1.5 times the IQR

Interquartile

Range (IQR)

EXPLANATION

Suspended Sediment  41
during stormflow. This report discusses results of 

suspended-sediment sampling from 1998 through 2005. 

Daily suspended-sediment yield was computed by dividing 

the daily suspended-sediment discharge by the drainage 

area and, in this report, is expressed in tons per day per 

square mile (tons/d/mi2). Von Guerard (1989a) indicated that 

the areas producing the largest suspended-sediment yields 

tended to be in streams on the readily erodible Colorado 

Piedmont. Between 1998 and 2001, daily suspended-sediment 

concentrations were measured, and suspended-sediment 

discharges were computed from April through September 

at six sites (table 1). Three sites in the Cottonwood Creek 

watershed and one site on Fountain Creek were discontinued 

after 2002: sites 07103977 (upper_CoCr), 07103980 

(middle_CoCr), 07103985 (TbCo), and 07103700 

(FoCr_Manitou). Daily suspended-sediment concentrations 

were measured and discharges were computed at two 

additional sites: 07104905 (MoCr_Bijou) on Monument 

Creek and 07105600 (SaCr) on Sand Creek, from 2003 to 

2006. Suspended-sediment concentration data were collected 

from April 1 through September 30 during 2003 through 

2006 because those months generally encompass the period 

that usually has appreciable stormflow. Data for all sites are 

published in Crowfoot and others (water years 1998–2005).

The base-flow separation program described earlier 

was used to identify daily suspended-sediment data as being 

associated either as base flow, normal flow, or as stormflow. 

These data were used to characterize suspended-sediment 

concentrations, suspended-sediment discharges, and 

suspended-sediment yields for base-flow, normal-flow, and 

stormflow conditions, which were then used to evaluate annual 

variations in suspended-sediment concentrations, suspendedsediment discharges, and suspended-sediment yields for 

base-flow, normal-flow, and stormflow conditions. Spatial 

variations in suspended-sediment concentrations, suspendedsediment discharges, and suspended-sediment yields also were 

evaluated.

A Mann-Whitney test of suspended-sediment concentrations, suspended-sediment discharges, and suspendedsediment yields evaluated statistical differences between 

adjacent sites during base flow, normal flow, and stormflow. 

Differences between tributaries during base flow, normal flow, 

and stormflow also were evaluated.

An evaluation of annual variations in suspendedsediment concentrations, suspended-sediment discharges, 

and suspended-sediment yields for base-flow, normal-flow, 

and stormflow conditions indicated that annual variations 

in suspended-sediment concentrations, suspended-sediment 

discharges, and suspended-sediment yields coincided with 

variations in the number of stormflow days. Suspendedsediment concentrations, discharges, and yields at sites in the 

Fountain Creek watershed were larger during wet years than 

during dry years. If the number of stormflow days during a 

year was greater than the average number of stormflow days 

per year plus one-half standard deviation, then the year was 

wet. If the number of stormflow days during a year was less 

than the average number of stormflow days per year minus 

one-half standard deviation, the year was considered dry.

Spatial Variations in Suspended-Sediment 

Concentrations

Base Flow

Spatial variations in suspended-sediment concentrations 

were observed between sites in the Monument Creek 

watershed during base flow (fig. 20A). Suspendedsediment concentrations increased between sites 07103970 

(MoCr_Woodmen) and 07104905 (MoCr_Bijou). The increase 

in suspended-sediment concentrations between site 07103970 

(MoCr_Woodmen) and site 07104905 (MoCr_Bijou) is 

likely the result of contributions of suspended sediment 

from intervening tributaries such as Cottonwood Creek, 

site 07103990 (lower_CoCr). Median suspended-sediment 

concentrations at site 07103990 (lower_CoCr) were 

significantly larger than median suspended-sediment 

concentrations at site 07103970 (MoCr_Woodmen) and 

site 07104905 (MoCr_Bijou) (table 5). Spatial variations 

in suspended-sediment concentrations between sites 

07104905 (MoCr_Bijou) and 07105500 (FoCr_Nevada) and 

sites 07105500 (FoCr_Nevada) and 07105800 (FoCr_Security) 

showed no significant differences during base flow (fig. 20A, 

table 5).

Normal Flow

Spatial variations of suspended-sediment concentrations 

in the Fountain and Monument Creek watersheds indicated 

that during normal flow, site 07103970 (MoCr_Woodmen) 

had the smallest suspended-sediment concentrations and 

site 07103990 (lower_CoCr) had the largest suspendedsediment concentrations (fig. 20A). Median suspendedsediment concentrations during normal flow tended to 

increase in a downstream direction and varied significantly 

between most sites (fig. 20A, table 5). Median suspendedsediment concentrations decreased significantly between sites 

07103990 (lower_CoCr) and 07104905 (MoCr_Bijou), and 

sites 07105600 (SaCr) and 07105800 (FoCr_Security) did not 

have significantly different median concentrations (fig. 20A, 

table 5) from one another. Site 07103990 (lower_CoCr) had 

significantly larger median suspended-sediment concentrations 

than site 07105600 (SaCr).

Stormflow

Spatial differences in suspended-sediment concentrations 

were observed between most sites in the Fountain and 

Monument Creek watersheds during stormflow (fig. 20A). 

On Monument Creek, suspended-sediment concentrations 

tended to increase in a downstream direction. Site 07103990 

(lower_CoCr) had the largest concentrations. Spatial variations 

42 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Figure 20. Variations in (A) suspended-sediment concentration, (B) suspended-sediment discharge, and (C) suspended-sediment yield 

for base flow, normal flow, and stormflow at selected main-stem and tributary sites in Fountain and Monument Creek watersheds, 1998 

through 2005.

07103970

07103990

07104905

07105500

07105600

07105800

Monument Creek Lower Fountain Creek

1

10

100

1,000

10,000

SUSPENDED-SEDIMENT CONCENTRATION,

 IN MILLIGRAMS PER LITER

SITE

0.1

1.0

10

100

1,000

10,000

100,000

SUSPENDED-SEDIMENT DISCHARGE,

 IN TONS PER DAY

(Note: 17 values less than 0.1 ton 

per day are not shown)

0.001

0.01

0.10

1

10

100

1,000

SUSPENDED-SEDIMENT YIELD, IN TONS

 PER DAY PER SQUARE MILE

0.0001

A

B

C

Base flow

Normal flow 

Stormflow

Outlier value

Outside value

75th percentile

Median

25th percentile

Smallest value within

1.5 times the IQR

Largest value within

1.5 times the IQR

Interquartile

Range

(IQR)

EXPLANATION

Suspended Sediment  43
Table 5. Median suspended-sediment concentration during base flow, normal flow, and stormflow in the Fountain and Monument 

Creek watersheds, and p-values of Mann-Whitney test of significance of spatial variations in suspended-sediment concentrations.

[Shaded cells indicate test is significant]

Site number

Median suspendedsediment 

concentration, 

in milligrams per liter

Median 

rank

Mann-Whitney test p-values of significance of spatial variation between sites

07103990 07104905 07105500 07105600 07105800

Base flow

07103970 196 1 0 0.0284

07103990 571 6 .0001 0.0792

07104905 245 4 0.7562

07105500 230 3 0.4781

07105600 310 5 .7640

07105800 225 2

Normal flow

07103970 42.0 1 0 0

07103990 357 6 0 0

07104905 119 2 0.0023

07105500 151 3 0.0198

07105600 186 5 .6845

07105800 159 4

Stormflow

07103970 505 1 0 0.0040

07103990 1,370 6 0 0

07104905 642 3 0.2345

07105500 786 4 0.0001

07105600 523 2 .0001

07105800 1,080 5

44  Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
07105500 (FoCr_Nevada) showed no significant differences 

during base flow (fig. 20B, table 6). Suspended-sediment 

discharges increased significantly between sites 07105500 

(FoCr_Nevada) and 07105800 (FoCr_Security) and between 

sites 07105600 (SaCr) and 07105800 (FoCr_Security) during 

base flow.

Normal Flow

Spatial differences in suspended-sediment discharge were 

observed between most sites in the Fountain Creek watershed 

during normal flow (fig. 20B). Median suspended-sediment 

discharges were significantly (p<0.05) different between 

several sites. Sites ranked from smallest to largest median 

suspended-sediment discharges during normal flow (table 6) 

were 07103970 (MoCr_Woodmen), 07105600 (SaCr), 

07103990 (lower_CoCr), 07104905 (MoCr_Bijou), 07105500 

(FoCr_Nevada), and 07105800 (FoCr_Security). Suspendedsediment discharge increased in a downstream direction as 

streamflow increased for the Fountain and Monument Creek 

sites (fig. 20B). All sites, except 07103990 (lower_CoCr) and 

07104905 (MoCr_Bijou), were significantly different from 

one another (table 6).

During normal flow, site 07103990 (lower_CoCr), a site 

with the smallest drainage area (18.7 mi2) and second smallest 

streamflow, had suspended-sediment discharges comparable 

or larger than sites with drainage areas 3 to 10 times larger. 

Suspended-sediment discharges at site 07103990 

(lower_CoCr) generally ranged from 3 to 10 tons/d (fig. 20B). 

Suspended-sediment discharges at site 07103970 

(MoCr_Woodmen), with a drainage area of 180 mi2 and 

located 0.5 mi upstream from Cottonwood Creek, generally 

ranged from 0.5 to 10 tons/d. Suspended-sediment discharges 

at site 07104905 (MoCr_Bijou), with drainage area of 

228 mi2 and located 0.7 mi upstream from the confluence 

with Fountain Creek, generally ranged from about 2 to more 

than 20 tons/d during normal flow. Suspended-sediment 

discharges at site 07105500 (FoCr_Nevada), drainage 

area 384 mi2 and located 1.3 mi downstream from the 

confluence with Monument Creek, generally ranged from 7 to 

80 tons/d during normal flow. Suspended-sediment discharges 

at site 07105600 (SaCr), with a drainage area of 52.6 mi2

and upstream from site 07105800 (FoCr_Security), generally 

ranged from about 1.5 to 6 tons/d during normal flow. The 

largest suspended-sediment discharges during normal flow 

occurred at site 07105800 (FoCr_Security), which had the 

largest drainage area (499 mi2) and largest streamflows; 

suspended-sediment discharge usually was larger than about 

80 tons/d and generally ranged from about 25 to 180 tons/

d. A Mann-Whitney test indicated significant differences 

in median suspended-sediment discharges between most 

sites. Differences in median suspended-sediment discharges 

between sites 07103990 (lower_CoCr) and 07104905 

(MoCr_Bijou) were not significant, indicating that sediment 

discharge from Cottonwood Creek may represent a significant 

fraction of sediment discharge at site 07104905 (MoCr_Bijou) 

in median suspended-sediment concentrations between sites 

07104905 (MoCr_Bijou) and 07105500 (FoCr_Nevada) 

showed no significant differences during stormflow (table 5). 

Suspended-sediment concentrations in lower Fountain Creek 

between sites 07105500 (FoCr_Nevada) and 07105800 

(FoCr_Security) showed a significant increase (table 5), 

indicating a substantial source of suspended sediments exists 

between these two sites. Suspended-sediment concentrations 

in Sand Creek, site 07105600 (SaCr), were significantly 

less than concentrations at site 07105800 (FoCr_Security) 

during stormflow. USGS personnel believe the Sand Creek 

watershed to be a major source area of suspended sediment 

to Fountain Creek and partly explains significant increases in 

stormflow suspended-sediment concentrations between sites 

07105500 (FoCr_Nevada) and 07105800 (FoCr_Security). 

An evaluation of differences between suspended-sediment 

concentrations of Cottonwood Creek and Sand Creek indicated 

that Cottonwood Creek tended to have larger suspendedsediment concentrations. Concentrations at site 07103970 

(MoCr_Woodmen) during stormflow generally were between 

about 200 and about 1,000 mg/L. Suspended-sediment 

concentrations at site 07103990 (lower_CoCr) generally 

ranged from 750 to 2,300 mg/L. At the two sites on Fountain 

Creek downstream from the confluence with Monument 

Creek (sites 07105500 [FoCr_Nevada] and 07105800 

[FoCr_Security]), suspended-sediment concentrations 

generally ranged between about 500 mg/L and 1,700 mg/L 

during stormflow. The largest suspended-sediment concentrations during stormflow were measured on Cottonwood 

Creek.

Spatial Variations in Suspended-Sediment 

Discharges

Base Flow

Spatial variations in suspended-sediment discharges were 

observed between sites 07103970 (MoCr_Woodmen) and 

07103990 (lower_CoCr) and between sites 07103990 

(lower_CoCr) and 07104905 (MoCr_Bijou) in the 

Monument Creek watershed during base flow (fig. 20B). 

Suspended-sediment discharges between sites 07103970 

(MoCr_Woodmen) and 07104905 (MoCr_Bijou) showed 

no significant differences during base flow (fig. 20, table 6). 

Median suspended-sediment discharges at site 07103990 

(lower_CoCr) were significantly larger than median 

suspended-sediment discharges at site 07103970 

(MoCr_Woodmen) and site 07104905 (MoCr_Bijou) (table 6). 

The lack of significant change in suspended-sediment 

discharges between sites 07103970 (MoCr_Woodmen) and 

07104905 (MoCr_Bijou) during base flow indicate that 

tributary inputs of suspended sediment are insignificant and 

(or) tributary inputs are being offset by in-channel storage 

along the reach. Spatial variations in suspended-sediment 

discharges between sites 07104905 (MoCr_Bijou) and 

Suspended Sediment  45
Table 6. Median suspended-sediment discharge during base flow, normal flow, and stormflow in the Fountain and Monument Creek 

watersheds, and p-values of Mann-Whitney test of significance of spatial variations in suspended-sediment discharge.

[Shaded cells indicate test is significant]

Site number

Median 

suspendedsediment 

discharge, 

in tons per day

Median rank

Mann-Whitney test p-values of significance of spatial variation between sites

07103990 07104905 07105500 07105600 07105800

Base flow

07103970 22.0 3 0.0052 0.0899

07103990 7.05 2 .0005 0.0127

07104905 26.0 4 0.0610

07105500 31.0 5 0

07105600 2.95 1 .0007

07105800 83.5 6

Normal flow

07103970 1.60 1 0 0

07103990 5.30 3 .5558 0.0013

07104905 5.70 4 0

07105500 17.0 5 0

07105600 2.95 2 0

07105800 54.0 6

Stormflow

07103970 90.0 1 0.0029 0.0042

07103990 166 3 .8780 0.7759

07104905 176 4 0.0007

07105500 361 5 0

07105600 142 2 0

07105800 1,430 6

46 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
suspended-sediment discharge at site 07103990 (lower_CoCr) 

to downstream sites indicated that if suspended-sediment 

discharge from 07103990 (lower_CoCr) remained in 

suspension along the intervening reach, it represented 

18 to 30 percent of the suspended-sediment discharge at 

site 07104905 (MoCr_Bijou) (table 7). Suspended-sediment 

discharge at site 07103970 (MoCr_Woodmen) can represent 

13 to 18 percent of the suspended-sediment discharge at 

site 07104905 (MoCr_Bijou) (table 7). Cumulative suspendedsediment discharge at site 07103970 (MoCr_Woodmen) 

and 07103990 (lower_CoCr) only accounted for about 

35 to 45 percent of suspended-sediment discharge at 

site 07104905 (MoCr_Bijou), indicating that additional 

sources of suspended-sediment discharge exist between sites 

07103970 (MoCr_Woodmen) and 07103990 (lower_CoCr) 

and site 07104905 (MoCr_Bijou). Cumulative suspendedsediment discharge at site 07104905 (MoCr_Bijou) 

generally was similar to suspended-sediment discharge at 

site 07105500 (FoCr_Nevada), ranging from 60 to 98 percent 

(table 7). Cumulative suspended-sediment discharge at 

site 07105500 (FoCr_Nevada) generally represented about 

70 percent of suspended-sediment discharge at site 07105800 

(FoCr_Security). The addition of site 07105600 (SaCr) to 

the monitoring network in 2003 provided evidence that 

Sand Creek contributed substantially to suspended-sediment 

discharge in Fountain Creek during storm runoff. Relative 

contributions of suspended-sediment discharge from 

site 07105600 (SaCr) to site 07105800 (FoCr_Security) 

ranged from 23 to 37 percent. In-channel storage of suspended 

sediment from gaged sites, suspended-sediment contributions 

from ungaged tributaries, and mobilization of in-channel 

sediments along the intervening reaches would decrease the 

relative contributions of suspended-sediment discharge from 

upstream to downstream sites. Sediment-source tracking 

evaluations are necessary to accurately define relative 

contributions of sediment from one location to another.

Spatial Variations in Suspended-Sediment 

Yields

Suspended-sediment yields normalize suspendedsediment discharges by dividing the sediment discharges by 

the drainage area. Suspended-sediment yields provide a means 

for identifying source-contribution areas.

Base Flow

Spatial variations in suspended-sediment yields were 

observed between sites 07103970 (MoCr_Woodmen) and 

07103990 (lower_CoCr) and between sites 07103990 

(lower_CoCr) and 07104905 (MoCr_Bijou) in the Monument 

Creek watershed during base flow (fig. 20C). Suspendedsediment yields between sites 07103970 (MoCr_Woodmen) 

and 07104905 (MoCr_Bijou) showed no significant 

differences during base flow (fig. 20C, table 8). 

during normal flow. However, in-channel storage of suspended 

sediment from Cottonwood Creek and contributions of 

suspended sediment from other tributaries and in-channel 

sources along the intervening reach also can explain the 

similarities in suspended-sediment discharge between sites 

07103990 (lower_CoCr) and 07104905 (MoCr_Woodmen). 

Median suspended-sediment discharges at 07103990 

(lower_CoCr) were almost 2 times larger than median 

suspended-sediment discharges at site 07105600 (SaCr).

Stormflow

During stormflow, site 07103970 (MoCr_Woodmen) 

generally had the smallest suspended-sediment discharges that 

generally ranged from about 20 to 250 tons/d. Site 07103990 

(lower_CoCr), the site with the smallest drainage area, had 

suspended-sediment discharges that generally ranged from 40 

to about 500 tons/d. Although site 07103990 (lower_CoCr) 

has a drainage area of about 18.7 mi2, almost 90 percent less 

drainage area than site 07103970 (MoCr_Woodmen), the 

median suspended-sediment discharge was almost 2 times 

larger than the median sediment discharge at site 07103970. 

Site 07105800 (FoCr_Security) had the largest suspendedsediment discharges that generally ranged from about 700 

to 4,000 tons/d during stormflow. Suspended-sediment 

discharges at site 07104905 (MoCr_Bijou) generally ranged 

from about 40 to 600 tons/d. Suspended-sediment discharges 

at site 07105500 (FoCr_Nevada), located a few miles 

upstream from site 07105800 (FoCr_Security) and about 

1.3 mi downstream from the confluence with Monument 

Creek, generally ranged from about 100 to 1,500 tons/d during 

stormflow. Suspended-sediment discharge at site 07105600 

(SaCr) generally ranged from about 40 to 500 tons/d, 

confirming earlier studies (Edelmann and others, 2002; 

von Guerard, 1989a) in which Sand Creek was identified as a 

major source of sediment between sites 07105500 

(FoCr_Nevada) and 07105800 (FoCr_Security) during 

stormflow.

Cumulative Suspended-Sediment Discharge

Variations in total cumulative daily suspended-sediment 

discharges from 1998 through 2001 and 2002 through 2005 

are shown in figures 21 and 22 and table 7. The April through 

September cumulative suspended-sediment discharges and 

streamflows were largest in 1999 at all sites, a result of a 

large storm that continued for 6 consecutive days between 

April 29 and May 4, 1999 (Edelmann and others, 2002). 

Total cumulative daily suspended-sediment discharges 

increased from upstream to downstream sites. Suspendedsediment discharges at Cottonwood Creek, site 07103990 

(lower_CoCr), generally were larger than suspended-sediment 

discharges from upper Monument Creek, site 07103970 

(MoCr_Woodmen), in 5 of 8 years, despite the larger drainage 

area at site 07103970. An evaluation of relative contribution of 

Suspended Sediment  47
Figure 21. Cumulative suspended-sediment discharge in the Fountain and Monument Creek watersheds, 1998 through 2001.

0 2.5 5 10 MILES

0 2.5 5 10 KILOMETERS

Bear Creek

Sand Creek

Monument Creek

Cottonwood Creek

Fountain Creek

Bear Creek

Sand Creek

Monument Creek

Cottonwood Creek

Fountain Creek

Bear Creek

Sand Creek

Monument Creek

Cottonwood Creek

Fountain Creek

Bear Creek

Sand Creek

Monument Creek

Cottonwood Creek

Fountain Creek

07105800 (FoCr_Security)

104°51’ 104°42’

38°48’

38°54’

104°51’ 104°42’

38°48’

38°54’

1998 1999

2000 2001

07103990

(lower_CoCr)

07105500

(FoCr_Nevada)

07103970

(MoCr_Woodmen)

07105800 (FoCr_Security)

07103990

(lower_CoCr)

07105500

(FoCr_Nevada)

07103970

(MoCr_Woodmen)

07105800 (FoCr_Security)

07103990

(lower_CoCr)

07105500

(FoCr_Nevada)

07103970

(MoCr_Woodmen) 07103990

(lower_CoCr)

07105500

(FoCr_Nevada)

07103970

(MoCr_Woodmen)

07105800 (FoCr_Security)

EXPLANATION

Military base or reservation

Municipal area

Suspended-sediment discharge,

 in tons, times 1,000

Less than 5

5 to 10

10.01 to 20

20.01 to 50

Greater than 50

Base from U.S. Geological Survey

Albers Equal-Area Conic projection

Standard parallels 37°30’N and 40°30’N

Central meridian 105°00’W

48 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Figure 22. Cumulative suspended-sediment discharge in the Fountain and Monument Creek watersheds, 2002 through 2005.

0 2.5 5 10 MILES

0 2.5 5 10 KILOMETERS

Bear Creek

Sand Creek

Cottonwood Creek

Bear Creek

Sand Creek

Cottonwood Creek

Bear Creek

Sand Creek

Cottonwood Creek

Bear Creek

Sand Creek

Monument Creek

Cottonwood Creek

104°51’ 104°42’

38°48’

38°54’

104°51’ 104°42’

38°48’

38°54’

Base from U.S. Geological Survey

Albers Equal-Area Conic projection

Standard parallels 37°30’N and 40°30’N

Central meridian 105°00’W

EXPLANATION

Military base or reservation

Municipal area

Suspended-sediment discharge,

 in tons, times 1,000

Less than 5

5 to 10

10.01 to 20

20.01 to 50

Greater than 50

Monument Creek

Monument Creek

Monument Creek

Fountain

Creek

Fountain

Creek

Fountain

Creek

Fountain

Creek

07105600 (SaCr)

07104905

(MoCr_Bijou)

07103990

(lower_CoCr)

07105500

(FoCr_Nevada)

07103970

(MoCr_Woodmen)

07105800 (FoCr_Security)

07105600 (SaCr)

07104905

(MoCr_Bijou)

07103990

(lower_CoCr)

07105500

(FoCr_Nevada)

07103970

(MoCr_Woodmen)

07105800 (FoCr_Security)

2002 2003

2004 2005

07103990

(lower_CoCr)

07105500

(FoCr_Nevada)

07103970

(MoCr_Woodmen)

07105800 (FoCr_Security)

07105600 (SaCr)

07104905

(MoCr_Bijou)

07103990

(lower_CoCr)

07105500

(FoCr_Nevada)

07103970

(MoCr_Woodmen)

07105800 (FoCr_Security)

Suspended Sediment  49
Table 7. Cumulative suspended-sediment discharge in the Fountain and Monument Creek watersheds, annually between April 1 and 

September 30, 1998, through 2005.

Site number

Suspendedsediment 

discharge, 

in tons per day

Relative percent 

contribution of suspendedsediment discharge to next 

downstream site

1998

07103970 11,800 17

07103990 9,630 14

07105500 69,400 48

07105800 144,000

1999

07103970 141,000 20

07103990 65,700 9

07105500 715,000 72

07105800 999,000

2000

07103970 3,960 9

07103990 19,700 45

07105500 43,800 70

07105800 62,500

2001

07103970 6,500 7

07103990 23,100 24

07105500 98,000 46

07105800 212,000

2002

07103970 2,890 10

07103990 8,250 28

07105500 29,800 45

07105800 66,400

Site number

Suspendedsediment 

discharge, 

in tons per day

Relative percent 

contribution of suspendedsediment discharge to next 

downstream site

2003

07103970 7,770 18

07103990 7,510 18

07104905 42,300 98

07105500 43,300 77

07105600 12,900 23

07105800 56,500

2004

07103970 6,890 14

07103990 14,800 30

07104905 50,000 60

07105500 83,400 71

07105600 35,000 30

07105800 118,000

2005

07103970 6,400 13

07103990 11,600 24

07104905 48,700 81

07105500 60,200 73

07105600 31,000 37

07105800 82,700

50 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Table 8. Median suspended-sediment yield during base flow, normal flow, and stormflow in the Fountain and Monument Creek 

watersheds, and p-values of Mann-Whitney test of significance of spatial variations in suspended-sediment yields.

[Shaded cells indicate test is significant]

Site number

Median 

suspendedsediment yield, 

in tons per day 

per square mile

Median rank

Mann-Whitney test p-values of significance of spatial variation between sites

07103990 07104905 07105500 07105600 07105800

Base flow

07103970 0.122 4 0 0.3376

07103990 0.377 6 .0001 0.0013

07104905 0.111 3 1.0000

07105500 0.079 2 0.0005

07105600 0.056 1 .0250

07105800 0.169 5

Normal flow

07103970 0.009 1 0 0

07103990 0.283 6 0 0

07104905 0.024 2 0.0002

07105500 0.043 3 0

07105600 0.056 4 .0018

07105800 0.109 5

Stormflow

07103970 0.500 1 0 0.0715

07103990 8.88 6 0 0.0005

07104905 0.749 2 0.2438

07105500 0.920 3 0

07105600 2.71 4 .6202

07105800 2.89 5

Suspended Sediment 51
Median suspended-sediment yields at site 07103990 

(lower_CoCr) were significantly larger than median 

suspended-sediment yields at site 07103970 

(MoCr_Woodmen) and site 07104905 (MoCr_Bijou) 

(table 8). Spatial variations in suspended-sediment yields 

between sites 07104905 (MoCr_Bijou) and 07105500 

(FoCr_Nevada) showed no significant differences during base 

flow (fig. 20C, table 8). Suspended-sediment yields increased 

significantly between sites 07105500 (FoCr_Nevada) and 

07105800 (FoCr_Security) and between sites 07105600 

(SaCr) and 07105800 (FoCr_Security) during base flow.

Normal Flow and Stormflow

During normal flow, the smallest yields were computed 

at site 07103970 (MoCr_Woodmen) (drainage area of 

180 mi2), and the yields ranged from 0.003 to 0.06 ton/d/mi2

(fig. 20C). Site 07103990 (lower_CoCr) (drainage area 

of 18.7 mi2) had the largest suspended-sediment yields, 

0.2 to 0.8 ton/d/mi2. Suspended-sediment yields increased 

progressively from site 07104905 (MoCr_Bijou) to 

site 07105800 (FoCr_Security) along the main-stem of 

Fountain and Monument Creeks. Analysis of the data between 

sites indicated that suspended-sediment yields varied by more 

than an order of magnitude during normal flow but generally 

were small. Although large spatial variations in suspendedsediment yields occurred during normal flow, the suspendedsediment yields that were associated with stormflow generally 

were more than 10 times larger than the suspended-sediment 

yields that occurred during normal flow.

A Mann-Whitney test of differences in median 

suspended-sediment yields between sites indicated significant 

(p<0.05) differences between all sites during normal flow and 

selected sites during stormflow (table 8). Median suspendedsediment yields increased progressively from site 07103970 

(MoCr_Woodmen) to 07105800 (FoCr_Security) along 

the main-stem of Fountain and Monument Creeks during 

normal flow and stormflow (fig. 20C). Median suspendedsediment yields at site 07103990 (lower_CoCr), which drains 

the Colorado Piedmont physiographic region (fig. 1), were 

larger than median yields at all sites during normal flow and 

stormflow, indicating the significance of Cottonwood Creek 

as a sediment source to Monument Creek and, ultimately, 

Fountain Creek (fig. 20C). Differences in median suspendedsediment yields between sites 07105600 (SaCr) and 07105800 

(FoCr_Security) were significant during normal flow but 

insignificant during stormflow (p>0.05) (table 8). The 

insignificant differences in yields during stormflow between 

sites 07105600 (SaCr) and 07105800 (FoCr_Security) indicate 

that yields from Sand Creek (area of 52.6 mi2) are comparable 

to yields at site 07105800 (FoCr_Security) (area of 499 mi2).

Variations in Instantaneous Streamflow, 

Suspended-Sediment Concentration, 

Suspended-Sediment Discharge, and 

Suspended-Sediment Yield at Selected 

Tributaries in the Fountain and Monument Creek 

Watersheds

Instantaneous suspended-sediment samples were 

collected at selected ungaged tributaries to better characterize 

the spatial variability of suspended sediment in the Fountain 

and Monument Creek watersheds. An ungaged site does not 

contain stream-stage recording equipment and was visited less 

frequently than the gaged sites, usually twice per year during 

normal flow and once per year during stormflow, to measure 

streamflow and collect water-quality and suspended-sediment 

samples. Due to the scope of sample collection at ungaged 

tributaries and the relatively short sampling period (2003 

through 2005), the number of samples collected and statistical 

tests available to analyze results were limited. Ungaged sites 

included previously gaged sites in the Cottonwood Creek 

watershed (sites 07103977, 07103980, and 07103985), Kettle 

Creek watershed (site 07103960), and nine additional sites 

on eight other tributaries that were added to the monitoring 

network prior to April 2003 (fig. 1). Tributaries varied in total 

area, physiographic region, and surficial geology.

Due to the relatively small drainage areas of the ungaged 

tributaries and the relatively small geographic extent of 

summertime convectional storms, storm runoff was very 

flashy, rising and falling rapidly. Measured streamflow at 

ungaged sites during normal flow was variable from site to 

site and generally was less than 10 ft3/s. Streamflow measured 

during stormflow ranged from about 0.8 ft3/s to about 

1,000 ft3/s. Stormflow duration information is limited for the 

ungaged tributaries; however, anecdotal evidence from field 

personnel collecting water-quality and suspended-sediment 

samples suggests that stormflow durations generally are less 

than 30 minutes to an hour at most sites for most convective 

storms.

Suspended-Sediment Concentrations at 

Selected Tributaries in the Fountain and 

Monument Creek Watersheds during Normal 

Flow and Stormflow

Suspended-sediment concentrations during normal flow 

varied considerably at individual sites and spatially between 

sites with median concentrations varying between 1 mg/L 

to greater than 1,000 mg/L (fig. 23). The largest range in 

suspended-sediment concentrations during normal flow was at 

52 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
site 07103980 (middle_CoCr). Site 07103980 (middle_CoCr) 

drains approximately 10.2 mi2 in the Colorado Piedmont 

physiographic region. Sites in the Colorado Piedmont and 

draining to Fountain and Monument Creeks from the east 

generally had the largest suspended-sediment concentrations. 

Sites in the Colorado Piedmont and Southern Rocky 

Mountains physiographic regions and draining to Fountain 

and Monument Creeks from the west generally had smaller 

suspended-sediment concentrations.

Suspended-sediment concentrations measured during 

stormflow varied at individual sites and spatially between 

sites with median concentrations ranging from 10 to more 

than 10,000 mg/L (fig. 23). The largest concentrations were 

measured in Kettle Creek, Cottonwood Creek, and Sand 

Creek, which drain the Colorado Piedmont from the east of 

Fountain and Monument Creeks, and North Rockrimmon 

Creek, which drain the Colorado Piedmont from the west of 

Monument Creek. Suspended-sediment concentrations during 

stormflow at sites draining the Colorado Piedmont ranged 

from about 800 to about 60,000 mg/L. Suspended-sediment 

concentrations at sites draining the Southern Rocky Mountains 

physiographic province (Bear Creek sites 07105000 and 

384909104504401) ranged from about 10 to about 1,000 mg/L 

(fig. 23); however, these data are based on a small number 

of storm samples from sites draining the Southern Rocky 

Mountains physiographic province.

Suspended-Sediment Discharges at Selected 

Tributaries in the Fountain and Monument Creek 

Watersheds during Normal Flow and Stormflow

Suspended-sediment discharge varied between sites 

during normal flow (fig. 24). Streamflows at sites with 

suspended-sediment discharges larger than 1 ton/d generally 

was larger than 1 ft3/s during normal flow. Streamflow during 

normal flow at sites with suspended-sediment discharge less 

than 1 ton/d generally was less than 1 ft3/s. Suspendedsediment discharge during normal flow was less than 

1 ton/d at sites on Kettle, Pine, Mesa, and Bear Creeks and 

unnamed tributaries to Monument and Cottonwood Creeks. 

Suspended-sediment discharge at sites on Cottonwood, North 

Rockrimmon, and Sand Creeks were larger than 1 ton/d 

(fig. 24). Drainage areas of sites with suspended-sediment 

discharges larger than 1 ton/d varied considerably. North 

Rockrimmon Creek at site 07104050 (NRCr) has a drainage 

area of about 1.8 mi2, Cottonwood Creek at site 07103990 

(lower_CoCr) has a drainage area of about 18.7 mi2, and Sand 

Creek at site 07105600 (SaCr) has a drainage area of about 

52.6 mi2. At site 07103985 (TbCo), suspended-sediment 

discharge during normal flow was smaller than 1 ton/d and it 

has a drainage area of 2.8 mi2.

Suspended-sediment discharge during stormflow varied 

spatially (fig. 24). Suspended-sediment discharge generally 

was larger than 100 tons/d at the ungaged tributaries and 

varied considerably between sites in the Colorado Piedmont 

and sites in the Front Range of the Colorado Rocky Mountains 

physiographic regions. Suspended-sediment discharge at 

sites in the Colorado Piedmont—Cottonwood Creek, Kettle 

Creek, and Sand Creek—ranged from about 1,000 to about 

10,000 tons/d. Suspended-sediment discharge at sites draining 

from the west in or near the Front Range of the Colorado 

Rocky Mountains physiographic province generally were less 

than 10 tons/d.

Suspended-Sediment Yields at Selected 

Tributaries in the Fountain and Monument Creek 

Watersheds during Normal Flow and Stormflow

The analysis of suspended-sediment yields during normal 

flow revealed that small tributaries such as North Rockrimmon 

Creek, which has an area of 1.82 mi2, contributed as much 

or more sediment per unit area as larger tributaries, such 

as Cottonwood Creek with a drainage area of 18.7 mi2. 

Median suspended-sediment yields during normal flow 

generally were less than 0.1 ton/d/mi2 (fig. 25) at most sites. 

Site 385501104483701 (TbMo), an unnamed tributary to 

Monument Creek near Pulpit Rock with a drainage area of 

0.691 mi2, had the smallest median suspended-sediment 

yields, less than 0.001 ton/d/mi2. Sites 07104050 (RkCr), with 

a drainage area of 1.82 mi2, and 07103980 (middle_CoCr), 

with a drainage area of 10.2 mi2, had the largest median 

suspended-sediment yields, larger than 1 ton/d/mi2. The largest 

tributary sites, 07103990 (lower_CoCr), with a drainage area 

of 18.7 mi2, and 07105600 (SaCr), with a drainage area of 

52.6 mi2, had median suspended-sediment yields of 0.1 to 

1 ton/d/mi2 and 0.01 to 0.1 ton/d/mi2, respectively. Spatially, 

sites draining from the east (Colorado Piedmont) generally had 

larger median suspended-sediment yields than sites draining 

from the west.

There was less spatial variation of median suspendedsediment yields of the ungaged tributaries during stormflow 

(fig. 25). Suspended-sediment yields during stormflow 

at sites 07103980 (middle_CoCr), 07103985 (TbCo), 

385750104475001 (PiCr), and 07104050 (RkCr) ranged 

between 10 and 100 tons/d/mi2 of drainage area. Suspendedsediment yields in Sand Creek (drainage area of 52.6 mi2

) 

were larger than 100 tons/d/mi2 during stormflow. Based on 

the few available data, suspended-sediment yields during 

stormflow at sites on Kettle, Pine, North Rockrimmon, and 

Mesa Creeks are comparable to Cottonwood and Sand Creeks.

Stream Morphology

Stream channels naturally change over time in response 

to streamflow characteristics and sediment delivery from the 

surrounding watershed. Change in streamflow characteristics 

and (or) sediment delivery from the surrounding watershed 

will in turn initiate a series of responses as the channel adjusts 

Stream Morphology 53
North Rockrimmon Creek

North Rockrimmon Creek

Mesa Creek

Mesa Creek

Kettle Creek

Kettle Creek

Sand Creek

Monument Creek

Bear Creek

Pine Creek

Fountain Creek

Sand Creek

Monument Creek

Bear Creek

Fountain Creek

Cottonwood

Creek

Cottonwood

Creek

Pine Creek

07105600 (SaCr)

07103985 (TbCo)

07103977 (upper_CoCr)

07103980 (middle_CoCr)

385750104475001 (PiCr)

385501104483701 (TbMo)

385854104470100 (upper_KeCr)

385204104510101 (upper_MeCr)

385124104501301 (lower_MeCr)

384909104504401

(lower_BeCr)

07104050 (RkCr)

07105000 (upper_BeCr)

07103990

(lower_CoCr)

07103960 (lower_KeCr)

07105600 (SaCr)

07103985 (TbCo)

07103977 (upper_CoCr)

07103980 (middle_CoCr)

385750104475001 (PiCr)

385501104483701 (TbMo)

385854104470100 (upper_KeCr)

385204104510101 (upper_MeCr)

385124104501301 (lower_MeCr)

384909104504401

(lower_BeCr)

07104050 (RkCr)

07105000 (upper_BeCr)

07103990

(lower_CoCr)

07103960 (lower_KeCr)

104°51’ 104°42’

38°48’

38°54’

38°48’

38°54’

Normal flow

Stormflow

0 1.25 2.5 MILES

0 1.25 2.5 KILOMETERS

EXPLANATION

Military base or reservation

Municipal area

Median

Less than 1

1.00 to 10

10.01 to 100

100.01 to 1,000

1,000.01 to 10,000

Greater than 10,000

Suspended-sediment

 concentration, in 

 milligrams per liter

Site with less than

 three storm samples

Base from U.S. Geological Survey

Albers Equal-Area Conic projection

Standard parallels 37°30’N and 40°30’N

Central meridian 105°00’W

Figure 23. Variations in suspended-sediment concentration during normal flow and stormflow at selected tributaries in the Fountain 

and Monument Creek watersheds.

54  Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
North Rockrimmon Creek

North Rockrimmon Creek

Mesa Creek

Mesa Creek

Kettle Creek

Kettle Creek

Sand Creek

Monument Creek

Bear Creek

Creek

Fountain Creek

Sand Creek

Monument Creek

Bear Creek

Pine

Fountain Creek

Cottonwood

Creek

Cottonwood

Creek

Pine Creek

Less than 0.01

0.01 to 0.1

0.11 to 1.0

1.01 to 10

10.01 to 100

100.01 to 1,000

Greater than 1,000

Site with less than 

 three storm samples

EXPLANATION

Military base or reservation

Municipal area

Median

Suspended-sediment

 concentration, in 

 tons per day

07105600 (SaCr)

07103985 (TbCo)

07103977 (upper_CoCr)

07103980 (middle_CoCr)

385750104475001 (PiCr)

385501104483701 (TbMo)

385854104470100 (upper_KeCr)

385204104510101 (upper_MeCr)

385124104501301 (lower_MeCr)

384909104504401

(lower_BeCr)

07104050 (RkCr)

07105000 (upper_BeCr)

07103990

(lower_CoCr)

07103960 (lower_KeCr)

07105600 (SaCr)

07103985 (TbCo)

07103977 (upper_CoCr)

07103980 (middle_CoCr)

385750104475001 (PiCr)

385501104483701 (TbMo)

385854104470100 (upper_KeCr)

385204104510101 (upper_MeCr)

385124104501301 (lower_MeCr)

384909104504401

(lower_BeCr)

07104050 (RkCr)

07105000 (upper_BeCr)

07103990

(lower_CoCr)

07103960 (lower_KeCr)

104°51’ 104°42’

38°48’

38°54’

38°48’

38°54’

Normal flow

Stormflow

0 1.25 2.5 MILES

0 1.25 2.5 KILOMETERS

Base from U.S. Geological Survey

Albers Equal-Area Conic projection

Standard parallels 37°30’N and 40°30’N

Central meridian 105°00’W

Figure 24. Variations in suspended-sediment discharge during normal flow and stormflow at selected tributaries in the Fountain and 

Monument Creek watersheds.

Stream Morphology 55
Figure 25. Variations in suspended-sediment yield during normal flow and stormflow at selected tributaries in Fountain and Monument 

Creek watersheds.

Pine Creek

Pine Creek

North Rockrimmon Creek

North Rockrimmon Creek

Mesa Creek

Mesa Creek

Kettle Creek

Kettle Creek

Sand Creek

Monument Creek

Bear Creek

Creek

Fountain Creek

Sand Creek

Monument Creek

Bear Creek

Fountain Creek

Cottonwood

Creek

Cottonwood

Less than 0.01

0.01 to 0.1

0.11 to 1.0

1.01 to 10

10.01 to 100

100.01 to 1,000

Greater than 1,000

Site with less than 

 three storm samples

EXPLANATION

Military base or reservation

Municipal area

Median

Suspended-sediment

 concentration, in 

 tons per day

07105600 (SaCr)

07103985 (TbCo)

07103977 (upper_CoCr)

07103980 (middle_CoCr)

385750104475001 (PiCr)

385501104483701 (TbMo)

385854104470100 (upper_KeCr)

385204104510101 (upper_MeCr)

385124104501301 (lower_MeCr)

384909104504401

(lower_BeCr)

07104050 (RkCr)

07105000 (upper_BeCr)

07103990

(lower_CoCr)

07103960 (lower_KeCr)

07105600 (SaCr)

07103985 (TbCo)

07103977 (upper_CoCr)

07103980 (middle_CoCr)

385750104475001 (PiCr)

385501104483701 (TbMo)

385854104470100 (upper_KeCr)

385204104510101 (upper_MeCr)

385124104501301 (lower_MeCr)

384909104504401

(lower_BeCr)

07104050 (RkCr)

07105000 (upper_BeCr)

07103990

(lower_CoCr)

07103960 (lower_KeCr)

104°51’ 104°42’

38°48’

38°54’

38°48’

38°54’

Normal flow

Stormflow

0 1.25 2.5 MILES

0 1.25 2.5 KILOMETERS

Base from U.S. Geological Survey

Albers Equal-Area Conic projection

Standard parallels 37°30’N and 40°30’N

Central meridian 105°00’W

56 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
to those changes (Leopold and others, 1964; Schumm, 1977; 

Karlinger and others, 1983).

Sediment-Transport Capacity

The ability of streamflow to transport sediment (transport 

capacity) can be described by using the Shields dimensionless 

shear-stress relation for estimating the particle size of bed 

material at the threshold of movement (von Guerard, 1989b). 

Maximum particle sizes of bed material transportable at 

various streamflows were estimated by using the following 

equation (von Guerard, 1989b; Elliott and others, 1984):

d DS c

s

w c

= 



 



 − 

































 



1 

*

(304.8) (1)

where

dc is particle size of bed material, at threshold of 

movement, in millimeters;

D is mean channel depth, in feet;

S is water-surface slope, dimensionless;





s

w

is ratio of specific weights of sediment and 

water (2.65), dimensionless;

 c

* is critical shear stress—the critical shear stress 

necessary for movement of bed material, 

dimensionless; and

304.8 is a unit conversion constant, in millimeters 

per foot.

Values of τ*

c of 0.030 and 0.045 were used as the upper and 

lower limits for the transport of coarse materials in Fountain 

Creek.

Streamflow (data from NWIS) and channel morphology 

data at sites on Cottonwood (07103980 (middle_CoCr), 

07103985 (Tb_Co), and 07103990 (lower_CoCr)); Kettle 

(07103960); Bear (07105000); Monument (07103970 

(MoCr_Woodmen) and 07104905 (MoCr_Bijou)); 

and Fountain (07103700 (FoCr_Manitou), 07105500 

(FoCr_Nevada), 07105530 (FoCr_Janitell), and 07105800 

(FoCr_Security)) Creeks were used to evaluate the capacity 

of streamflows to transport coarse sand and gravel of 1- to 

32-mm-size fractions, the predominant size fraction in 

Fountain, Monument, and Cottonwood Creeks (table 9) 

(Harrelson and others, 1994; Wolman, 1954). Analyses 

indicate that minimum measured streamflows at all sites have 

the capacity (table 10) to transport coarse to very coarse sands 

of 1 to 2 mm (τ*

c = 0.045). The transport of bed material of 

the coarse gravel of 16- to 32-mm-size fractions is possible 

(τ*

c

= 0.045) as streamflows approach and exceed 20 ft3/s to 

30 ft3/s at sites in the Cottonwood Creek watershed, 07103980 

(middle_CoCr), 07103985 (TbCo), and 07103990 

(lower_CoCr); and 130 ft3/s to 150 ft3/s at site 07103970 

(MoCr_Woodmen), 130 ft3/s to 250 ft3/s at site 07104905 

(MoCr_Bijou) in Monument Creek; 5 ft3/s to 10 ft3/s at 

site 07103700 (FoCr_Manitou), 50 ft3/s to 120 ft3/s at 

site 07105500 (FoCr_Nevada), 100 ft3/s to 200 ft3/s at 

site 07105530 (FoCr_Janitell), and 130 ft3/s to 600 ft3/s 

at site 07105800 (FoCr_Security) in Fountain Creek. The 

maximum measured streamflows at sites 07103700 

(FoCr_Manitou), 07103990 (lower_CoCr), 07105000 

(upper_BeCr), and 07105500 (FoCr_Nevada) also have 

sufficient energy to initiate movement of bed material in the 

cobble-size fraction (64 to 256 mm) (τ*

c

 = 0.045).

Descriptive Assessment of Changes in Channel 

Morphology

Substantial changes in channel morphology are most 

often associated with infrequent or catastrophic floods that 

may cause rapid changes in channel shape and (or) location 

and capture the attention of area residents. However, more 

common streamflow conditions associated with bankfull 

streamflow, while less catastrophic, are considered the 

dominant force in development and maintenance of channel 

morphology (Leopold and others, 1964; Wolman and Miller, 

1960). Changes in channel morphology for one reach of 

Monument Creek near site 07103970 (MoCr_Woodmen), 

two reaches of Fountain Creek near sites 07103700 

(FoCr_Manitou) and 07105800 (FoCr_Security), four reaches 

of Cottonwood Creek near sites 07103977 (upper_CoCr), 

07103980 (middle_CoCr), 07103985 (TbCo), and 07103990 

(lower_CoCr), and one reach of Sand Creek (07105600) 

are described using periodic cross-section surveys made 

by Colorado Springs City Engineering employees from 

1999 through 2005 (Joel Mackey, Colorado Springs City 

Engineering, unpub. data, 2006). In addition to surveys of 

selected reaches conducted by City of Colorado Springs City 

Engineering employees, individual cross sections at or near 

sites 07104000 (MoCr_Pikeview), 07104905 (MoCr_Bijou), 

and 07105530 (FoCr_Janitell) were surveyed (Kennedy, 1990) 

periodically by USGS employees. Cross-section surveys 

documented channel downcutting, channel aggradation or 

infilling, and bank scour that have occurred between 1999 and 

2005.

Bulk density of bed materials in Fountain and Monument 

Creeks was not determined as part of this investigation. 

Sediment deposits analogous to the sand and gravel composition of the beds of Fountain and Monument Creeks 

and their tributaries would undoubtedly vary considerably 

depending on horizontal and vertical particle-size distribution 

and other factors such as compaction. Anderson (1973) and 

Meade (1985) suggest that bulk densities of sand and gravel 

mixtures range from 60 to 100 lb/ft3.

For the purpose of this report, cross-section area refers 

to the cross-section sediment area (fig. 26) above an arbitrary 

datum within the surveyed cross section. Sediment volume 

Stream Morphology 57
Table 9. Particle-size distribution for bed material at sites in the Fountain and Monument Creek watersheds based on pebble counts 

measured between 1998 and 2005.

[<, less than; >, greater than; percentages may not equal 100 because of rounding]

Site number

Size class (Wentworth)2

Silt/Clay Sand Gravel Cobble Boulder3 Bedrock3

Range in particle size, in millimeters

<0.0625 0.0625 – 2 2 – 64 64 – 256 256 – 4,096 >4,096

in percent

Tributaries

385854104470100, upper_KeCr 33 45 22 0 0 0

07103960, lower_KeCr 34 40 24 1 0 1

385750104475001, PiCr 32 46 19 1 0 3

071039761 8 45 46 0 0 0

071039781 24 52 21 0 0 3

07103980, middle_CoCr 10 44 28 0 2 15

07103985, TbCo 11 57 24 4 4 0

07103990, lower_CoCr 7 32 21 1 5 34

385501104483701, TbMo 29 42 21 2 6 1

385204104510101, upper_MeCr 60 6 25 3 1 5

385124104501301, lower_MeCr 71 8 16 4 0 0

07105000, upper_BeCr 21 16 44 6 13 0

Main stem

07103700, FoCr_Manitou 13 27 40 13 8 0

07103707, FoCr_8th 13 45 32 5 6 0

07103970, MoCr_Woodmen 13 36 46 3 1 2

07104905, MoCr_Bijou 7 54 38 0 1 1

07105500, FoCr_Nevada 8 42 39 2 9 0

07105530, FoCr_Janitell 8 31 29 8 19 5

07105800, FoCr_Security 8 33 42 3 4 9

1

Site numbers 07103976 and 07103978 are unofficial site numbers and represent sites located immediately upstream and downstream from site 07103977 

(upper_CoCr).

2

Dunne, Thomas, and Leopold, L.B., 1978, Water in environmental planning: New York, W.H. Freeman and Company, 818 p.; and 

Gordon, Nancy D., McMahon, Thomas A., Finlayson, Brian L., Gippel, Christopher J., and Nathan, Rory J., 2004, Stream hydrology, an introduction for

ecologists: West Sussex, John Wiley and Sons, Ltd., 429 p. 

3

Modified size classes for this report.

58 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Table 10. Range in particle size of bed material, in millimeters, at threshold of movement for upper and lower limits of transport of 

coarse materials based on minimum and maximum measured streamflow in the Fountain and Monument Creek watersheds.

[τ*

c

, critical shear stress necessary to initiate movement of bed material, dimensionless; 0.030, upper limit of τ*

c

; 0.045 lower limit of τ*

c

; mm, millimeters ]

Site number Channel 

slope

τ*

c

0.030 0.045

Minimum 

particle 

size 

(mm)

Maximum particle

size 

(mm)

Minimum 

particle 

size 

(mm)

Maximum 

particle 

size 

(mm)

Tributaries

07103960, lower_KeCr 0.014 5.75 29.2 3.83 19.4

07103980, middle_CoCr .012 8.31 32.5 5.54 21.7

07103985, TbCo .008 7.09 46.8 4.73 31.2

07103990, lower_CoCr .020 15.9 131 10.6 87.6

07105000, upper_BeCr .062 42.0 175 28.0 116

Main stem

07103700, FoCr_Manitou 0.013 19.2 326 12.8 217

07103970, MoCr_Woodmen .005 7.02 90.3 4.68 60.2

07104905, MoCr_Bijou .004 4.67 37.8 3.12 25.2

07105500, FoCr_Nevada .006 9.33 191 6.22 128

07105530, FoCr_Janitell .005 11.1 66.8 7.36 44.5

07105800, FoCr_Security .004 8.55 93.0 5.70 62.0

Stream Morphology 59
Figure 26. Computation of cross-section sediment area and reach sediment volume.

Cross-section sediment area

survey monument survey point along cross section 

w

 h

computed sediment area

Sediment area = 31 surveyed height of sediment (h) * subsection width (w) n

subsection width (w) = 3 1⁄2 distance between survey points (see above diagram)

Reach sediment volume

Cross section #1 (XS1)

subreach 1 length (L1) = distance between XS1 and XS2

Cross section #2 (XS2)

subreach 2 length (L2) = distance between XS2 and XS3

Cross section #3 (XS3)

 subreach 3 length (L3) = distance between XS3 and XS4

Cross section #4 (XS4)

 subreach 4 length (L4) = distance between XS4 and XS5

Cross section #5 (XS5)

Sediment volume = area XS1 * 1⁄2 L1 + area XS2 * 1⁄2 L1 + area XS2 * 1⁄2 L2 + area XS3 * 1⁄2 L2 + area XS3 * 1⁄2 L3

+ area XS4 * 1⁄2 L3+ area XS4 * 1⁄2 L4 + area XS5 * 1⁄2 L4

60 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
refers to the estimated volume of sediment within the surveyed 

reach (fig. 26). Data presented with regard to volume of 

channel downcutting or infilling do not represent total bedload 

transport for a given period at a given site, only net change in 

channel volume from one survey period to the next. Therefore, 

the gains and (or) losses in volume of bed and bank material 

cannot be used as a surrogate for bedload in conjunction with 

suspended-sediment data to compute total sediment load for a 

site.

Cottonwood Creek

Bed material in the Cottonwood Creek channel 

ranges from primarily sand and gravel in its upper reaches 

(site 07103977 [upper_CoCr], referred to as sites 07103976 

and 07103978 in table 9) to bedrock and sand at its confluence with Monument Creek (site 07103990 [lower_CoCr]) 

(table 9). Channel morphology in the upper reach of Cottonwood Creek (07103977 [upper_CoCr]) changed between 1999 

and 2005. Surveys of five cross sections along a 219-ft reach 

indicate channel aggradation and widening and (or) lateral 

migration. Cross sections aggraded 0.36 to 1.39 ft between 

October 1999 and October 2005 (fig. 27, table 11). Channel 

migration is apparent at the upper three cross sections as one 

bank is aggrading while the opposite bank is eroding. The 

slope of the channel has increased 0.00165 from 0.02081 

to 0.02246. Increases in the slope of the channel affect 

sediment-transport characteristics and result in increased 

transport capacity without an increase in streamflow. The 

volume of bed and bank material decreased between October 

1999 and October 2005 (fig. 28). Bank erosion generally has 

exceeded channel aggradation with an estimated net loss of 

about 2,200 ft3 from the reach at site 07103977 (upper_CoCr) 

during October 1999 to October 2005 (table 12). Based on 

the probable range in bulk density of sand and gravel deposits 

and the net change in reach volume, 65.6 to 109 tons has been 

removed from this reach (table 12) between October 1999 and 

October 2005.

Changes in channel morphology in the central reach 

(07103980 [middle_CoCr]) are dominated by channel 

widening and downcutting. The four most-upstream cross 

sections indicate widening and channel downcutting while 

the most-downstream cross section indicates that the channel 

is widening and infilling. The minimum bed altitude at the 

four upstream cross sections degraded by 0.55 to 1.37 ft, and 

the downstream cross section aggraded 0.32 ft (table 11), 

resulting in a 0.00533 decrease in slope through the reach. 

During the period from October 1999 through October 2005, 

annual changes in sediment volume have included increases 

in sediment volume as material was deposited within the 

reach and decreases as materials were scoured from the reach 

(fig. 28). As of October 2005, sediment volume within this 

reach had decreased 9,700 ft3 (fig. 28) (table 12), primarily 

due to bed and bank erosion in the upstream portion of the 

reach and bank erosion in the downstream portion. Based on 

the possible range in bulk density of sand and gravel deposits 

and the net change in sediment volume, 290 to 480 tons 

(table 12) of sand and gravel was removed from this reach.

One tributary to Cottonwood Creek (07103985 [TbCo]) 

also was surveyed to evaluate changes in channel morphology. 

Cross-section surveys indicate downcutting as the dominant 

in-channel process; degradation ranged from 0.3 to 1.65 ft 

(table 11) along the reach. However, flood-plain deposition 

exceeded in-channel downcutting as the area at one cross 

section decreased 10.9 ft2 and areas at four cross sections 

increased by 37.8 to 263 ft2, and sediment volume increased 

22,200 ft3 (table 12) between October 2000 and October 

2005 (fig. 28). The slope of the reach decreased 0.00472 

as a result of downcutting. Based on the probable range in 

bulk density of sand and gravel deposits and the net change 

in sediment volume, 670 to 1,100 tons (table 12) has been 

deposited mainly in the overbank areas of this reach. Changes 

measured within this reach may be attributable to the rapid 

changes in land use within the watershed. Impervious area 

within the watershed increased 15 percent between 1997 and 

2005, or about 2 percent per year (table 2). Increases in storm 

runoff generally coincides with increases in imperviousness. 

Increases in storm runoff likely increases the transport 

capacity and competence of streamflow. Larger streamflows 

might explain the downcutting of the bed and likely would 

result in more frequent overbank flows. Coarse material 

transported by the larger streamflows would settle out of the 

water column as velocities decrease in the area of overbank 

flows because streamflows are generally shallower and slower 

as resistance to the flow increases due to bank vegetation. 

The pattern of downcutting and bank deposition is likely to 

continue until the channel establishes a quasi-equilibrium with 

the current flow regime and sediment inputs.

Changes in morphology of the lower reach of 

Cottonwood Creek (07103990 (lower_CoCr)) generally 

were smaller than changes in the upstream reaches due to the 

increasingly common incidence of shale bedrock. Historically, 

however, changes in channel morphology in regions of 

bedrock outcroppings also have been substantial. Streamflow 

can slowly erode bedrock along fractures, at times developing 

subsurface channels capable of conveying most if not all 

streamflow during periods of low streamflow. Over time and 

during selected periods of high streamflow, the undermined 

shale is subsequently removed in small to large sheets in 

relatively short periods of time (Jim Bruce, U.S. Geological 

Survey, oral commun., 2001). Between October 1999 and 

October 2005, bank erosion resulting in channel widening was 

the dominant process altering the morphology of this reach. 

Channel degradation ranged from 0.28 to 0.79 ft as a result 

of downcutting, and cross-sectional sediment areas decreased 

31.4 to 225 ft2 due to bank erosion. Slope change was 

negligible, 0.00001, as downcutting was not a major process 

in this reach. Sediment volume decreased 24,100 ft3 (table 12) 

between October 1999 and October 2005 as a result of bank 

erosion. Based on the probable range in bulk density of sand 

and gravel deposits and the net change in sediment volume, 

approximately 723 to 1,200 tons (table 12) has been removed 

from this reach.

Stream Morphology 61
Figure 27. Change in minimum streambed altitude at cross sections along selected reaches of Cottonwood Creek near 

sites 07103977 (upper_CoCr), 07103980 (middle_CoCr), 07103985 (TbCo), and 07103990 (lower_CoCr), October 1999 through 

October 2005.

0 50 100 150 200 250 300

70

71

72

73

74

75

76

0 50 100 150 200 250

82

83

84

85

86

87

88

07103977 (upper_CoCr)

0 50 100 150 200

ALTITUDE ABOVE AN ARBITRARY DATUM, IN FEET

82

83

84

85

86

87

88

89

October 1999

October 2000

October 2001

October 2002

October 2003

October 2004

October 2005

07103990 (lower_CoCr)

DISTANCE DOWNSTREAM, IN FEET FROM FIRST CROSS SECTION

0 50 100 150 200 250 300

71

72

73

74

75

76

77

78

ALTITUDE ABOVE AN ARBITRARY DATUM, IN FEET

DISTANCE DOWNSTREAM, IN FEET FROM FIRST CROSS SECTION

07103980 (middle_CoCr)

07103985 (TbCo)

October 2000

October 2001

October 2002

October 2003

October 2004

October 2005

October 2000

October 2001

October 2002

October 2003

October 2004

October 2005

October 1999

October 2000

October 2001

October 2002

October 2003

October 2004

October 2005

62 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Table 11. Change in minimum bed altitude, cross-section sediment area, and estimated mass of sediment eroded or deposited at 

selected cross sections in the Fountain and Monument Creek watersheds, 1999 through 2005.—Continued

[ID, identifier; ft, feet; ft2, square feet; lb/ft3, pounds per cubic foot]

Site number1

Crosssection 

ID2

Change

in minimum 

bed altitude 

(ft)

Change in 

cross-section 

sediment area

(ft2)

Mass of sediments 

eroded (–) or deposited,

 in tons

Bulk density, 

in lb/ft3

60 100

Main stem

07103700 (FoCr_Manitou) 10-9 –0.86 –20.2 –0.60 –1.01

8-7 .86 7.33 .22 .36

6-5 .73 18.8 .56 .94

4-3 .09 10.0 .30 .50

2-1 .46 6.04 .18 .30

07103970 (MoCr_Woodmen) 4-9 –.65 –24.4 –.73 –1.22

2-7 –.52 –22.4 –.67 –1.12

2-5 .09 41.8 1.25 2.09

2-3 .25 –39.9 –1.20 –1.99

2-1 .66 68.6 2.06 3.43

07104000 (MoCr_Pikeview) a –.58 –60.3 –1.81 –3.02

b –1.67 –55.1 –1.65 –2.76

07104905 (MoCr_Bijou) –.76 –52.6 –1.63 –2.63

07105530 (MoCr_Janitell) –1.28 –24.0 –.72 –1.20

07105800 (FoCr_Security) 10-9 –.26 –114 –3.42 –5.70

8-7 –.26 –191 –5.70 –9.55

6-5 –.11 –135 –4.05 –6.75

4-3 –.53 –45.0 –1.35 –2.25

2-1 –.85 4.84 .14 .24

Stream Morphology 63
Table 11. Change in minimum bed altitude, cross-section sediment area, and estimated mass of sediment eroded or deposited at 

selected cross sections in the Fountain and Monument Creek watersheds, 1999 through 2005.—Continued

[ID, identifier; ft, feet; ft2, square feet; lb/ft3, pounds per cubic foot]

Site number1

Crosssection 

ID2

Change

in minimum 

bed altitude 

(ft)

Change in 

cross-section 

sediment area

(ft2)

Mass of sediments 

eroded (–) or deposited,

 in tons

Bulk density, 

in lb/ft3

60 100

Tributary

07103977 (upper_CoCr) 8-7 1.16 –3.04 –0.09 –0.15

6-7 .80 17.8 .53 .89

4-5 1.39 15.5 .46 .78

2-3 .36 –77.0 –2.31 –3.85

2-1 .79 –6.98 –.0001 –.34

07103980 (middle_CoCr) 10-9 –1.37 –40.5 –1.22 –2.02

8-7 –.98 –54.6 –1.64 –2.73

6-5 –.93 31.6 .94 1.58

4-3 –.55 –23.2 –.70 –1.16

2-1 .32 –114 –3.42 –5.70

07103985 (TbCo) 6-7 –1.65 37.8 1.13 1.89

4-7 –.30 73.2 2.20 3.66

2-5 –.99 –10.9 –.32 –.54

2-3 –.51 146 4.28 7.30

2-1 –.41 263 7.89 13.2

07103990 (lower_CoCr) 7-8 –.29 –225 –6.00 –11.2

5-8 –.77 –145 –4.35 –7.25

3-6 –.53 –31.4 –.94 –1.57

3-4 –.79 .58 .02 .29

1-2 –.28 –59.4 –1.78 –2.97

07105600 (SaCr) 10-9 .17 –38.6 –1.16 –1.93

8-7 1.81 201 6.00 10.0

6-5 1.05 204 6.10 10.2

4-3 .99 165 4.95 8.25

2-1 .38 –28.1 –.84 –1.40

1

See figure 1.

2

Colorado Springs City Engineering.

64  Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Figure 28. Cumulative change in volume of sediments of selected reaches of Cottonwood Creek near sites 07103977 (upper_CoCr), 

07103980 (middle_CoCr), 07103985 (TbCo), and 07103990 (lower_CoCr), 1999 through 2005.

1999 2000 2001 2002 2003 2004 2005 2006 1999 2000 2001 2002 2003 2004 2005 2006

CUMULATIVE CHANGE IN SEDIMENT VOLUME, IN CUBIC FEET CUMULATIVE CHANGE IN SEDIMENT VOLUME, IN CUBIC FEET

DATE DATE

1999 2000 2001 2002 2003 2004 2005 2006

0

1999 2000 2001 2002 2003 2004 2005 2006

-15,000

-10,000

-5,000

0

5,000

10,000

15,000

20,000

25,000

–12,000

–10,000

–8,000

–6,000

–4,000

–2,000

0

-30,000

-25,000

-20,000

-15,000

-10,000

-5,000

5,000

10,000

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

07103977 (upper_CoCr)

07103990 (lower_CoCr)

07103980 (middle_CoCr)

07103985 (TbCo)

Monument Creek

Bed material of Monument Creek at site 07103970 

(MoCr_Woodmen) is primarily sand and gravel (table 9). 

Surveys of cross sections along this reach since the 1999 

flood have documented episodes of channel degradation 

and aggradation. Channel geometry as defined by the 

most recent series of cross-section surveys, October 2005, 

indicates that banks are generally stable and little lateral 

movement of banks has occurred in this reach. Episodes of 

aggradation and degradation appear to be limited to the bed. 

Between October 2000 and October 2005, the upper cross 

sections of this surveyed reach have tended to downcut, and 

degradation ranged from 0.65 to 0.52 ft (fig. 29, table 11). 

The down-stream cross sections of the reach have tended to 

infill, aggrading 0.09 ft to 0.66 ft. Between October 2000 and 

October 2005, the cross-sectional sediment area in the middle 

cross section of the reach increased, aggrading 41.8 ft2, and the 

cross-sectional sediment area in the most-downstream cross 

section increased, aggrading 68.6 ft2.Cross-sectional sediment 

areas of the remaining three cross sections decreased, 

degrading 22.4 to 39.9 ft2 (table 11). The slope of the reach 

has decreased 0.00356 ft/ft as a result of downcutting in the 

upstream sections of the reach, and sediment volume has 

decreased 4,800 ft3 (fig. 30, table 12). Based on the probable 

range in bulk density of sand and gravel deposits and the net 

change in sediment volume, approximately 145 to 242 tons 

(table 12) has been removed from this reach.

Cross-section surveys near site 07104000 (MoCr_Pikeview) (07104000a and 07104000b) document gradual 

downcutting of the channel. At the upstream cross section, 

07104000a, changes in channel cross section varied from one 

survey to the next; degradation ranged from 0.1 to 0.4 ft, and 

aggradation ranged from 0.1 to 0.5 ft. Between July 2003 

and July 2006, maximum channel degradation was 1.1 ft. 

Stream Morphology 65
Table 12. Estimated mass of sediment eroded or deposited from selected reaches of Fountain, Monument, Cottonwood, and Sand 

Creeks, 1999 through 2005.

[ft3, cubic foot; lb, pound; lb/ft3, pound per cubic foot]

Site number and 

abbreviation

Net change in 

sediment volume

(ft3)

Mass of material eroded (–) or deposited

(lb)

Mass of material eroded (–) or deposited

(tons)

Bulk density Bulk density

60 lb/ft3 100 lb/ft3 60 lb/ft3 100 lb/ft3

07103700, FoCr_Manitou 2,200 130,000 216,000 64.9 108

07103970, MoCr_Woodmen –4,800 –291,000 –485,000 –145 –242

07103977, upper_CoCr –2,200 –131,000 –219,000 –65.6 –109

07103980, middle_CoCr –9,700 –581,000 –968,000 –290 –480

07103985, TbCo 22,200 1,340,000 2,230,000 670 1,100

07103990, lower_CoCr –24,100 –1,450,000 –2,410,000 –723 –1,200

07104000, MoCr_Pikeview –3,270,000 –19,600,000 –32,600,000 –9,800 –16,300

07105600, SaCr 112,000 6,710,000 11,200,000 3,360 5,600

07105800, FoCr_Security –124,000 –7,460,000 –12,000,000 –3,730 –6,210

Subsequent channel infilling reduced the net downcutting 

to 0.58 ft (table 11). In addition to the channel degradation, 

the cross-sectional sediment area decreased as channel 

downcutting along the entire cross section exceeded infilling. 

From July 2003 through July 2006, the cross-sectional 

sediment area decreased by 60.3 ft2, an average of about 20 ft2

per year, as the bed altitude was lowered. Based on the range 

in bulk density of sand and gravel samples, an estimated 

1.81 to 3.02 tons of bed sediments was removed from the 

cross section during the period July 2003 through July 2006 

(table 11).

At downstream site 07104000b, variations in channel 

morphology between one cross section and the next were 

larger than variations at upstream site 07104000a; channel 

degradation ranged from 0.0 to 2.25 ft, and channel 

aggradation varied from 0.0 to 1.3 ft. The cross-sectional 

sediment area at site 07104000b has decreased by 55.1 ft2

(table 11) as a result of downcutting between July 2003 and 

July 2006, an average of about 18 ft2 per year. Based on the 

range in bulk density of sand and gravel samples, an estimated 

1.65 to 2.76 tons (table 11) of bed sediments has been 

removed from the cross section during the period July 2003 

through July 2006.

If net change in cross-sectional sediment area along the 

1.1-mi-long reach between site 07104000a and 07104000b 

is similar to changes in cross-section area at sites 07104000a 

and 07104000b, then about 3,270,000 ft3 of sand and gravel 

has been removed and transported downstream. This is an 

average of about 1,090,000 ft3 of material per year between 

July 2003 and July 2006. Based on the range in bulk density, 

an estimated 9,800 to 16,300 tons (an average of 3,200 to 

5,400 tons per year) of sand and gravel has been eroded 

from the bed of Monument Creek within the reach near 

site 07104000 (table 12).

Bed material of Monument Creek at site 07104905 

(MoCr_Bijou) also is primarily sand and gravel (table 9). 

Surveys of cross sections since 2003 have documented 

episodes of channel downcutting and infilling. Channel 

downcutting has ranged from 0.04 to 1.2 ft, and channel 

infilling has ranged from 0.16 to 1.3 ft. As of July 2006, the 

channel has degraded about 0.76 ft, and the cross-sectional 

sediment area has decreased 52.6 ft2 (table 11). Based on the 

range in bulk density of sand and gravel samples, an estimated 

1.63 to 2.63 tons (table 11) of bed sediments has been 

removed from the cross section during the period July 2003 

through July 2006, an average of 0.5 to 0.9 ton per year.

Fountain Creek

Bed and bank material of Fountain Creek at sites 

07103700 (FoCr_Manitou), 07105530 (FoCr_Janitell) , and 

07105800 (FoCr_Security) consists primarily of sand and 

gravel (table 9). Surveys of cross sections at these sites since 

1999 have documented episodes of channel degradation and 

aggradation.

Cross-section surveys between October 1999 and 

October 2005 at site 07103700 (FoCr_Manitou) indicate that 

the channel has degraded 0.86 ft at the most-upstream cross 

section due to downcutting, and the channel has aggraded 0.09 

to 0.86 ft (fig. 31, table 11) at cross sections downstream due 

to infilling. Cross-section area decreased 20.2 ft2 at the most 

upstream cross section and increased 6.04 to 18.8 ft2 (table 11) 

at the cross sections downstream. The slope of the channel 

decreased 0.00685, and the sediment volume increased 

66 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Figure 29. Change in minimum streambed altitude at cross sections along a reach of Monument Creek near 

site 07103970 (MoCr_Woodmen), October 2000 through October 2005.

Figure 30. Cumulative change in volume of sediments of a reach of Monument Creek near 

site 07103970 (MoCr_Woodmen), 2000 through 2005.

October 2000

October 2001

October 2002

October 2003

October 2004

October 2005

DISTANCE DOWNSTREAM, IN FEET FROM FIRST CROSS SECTION

0 100 200 300 400 500

ALTITUDE ABOVE AN ARBITRARY DATUM, IN FEET

86.0

86.5

87.0

87.5

88.0

88.5

89.0

89.5

90.0

DATE

2000 2001 2002 2003 2004 2005 2006

CUMULATIVE CHANGE IN SEDIMENT VOLUME, IN CUBIC FEET –6,000

–4,000

–2,000

0

2,000

4,000

6,000

Stream Morphology 67
Figure 31. Change in minimum streambed altitude at cross sections along selected reaches of 

Fountain Creek near sites 07103700 (FoCr_Manitou) and 07105800 (FoCr_Security), October 1999 

through October 2005.

07103700 (FoCr_Manitou)

0 100 200 300

93

94

95

96

97

98

99

100

DISTANCE DOWNSTREAM, IN FEET FROM FIRST CROSS SECTION

0 200 400 600 800 1,000 1,200

612

614

616

618

620

622

624

07105800 (FoCr_Security)

ALTITUDE ABOVE AN ARBITRARY DATUM, IN FEET ALTITUDE ABOVE AN ARBITRARY DATUM, IN FEET

October 1999

October 2000

October 2001

October 2002

October 2003

October 2004

October 2005

October 1999

October 2000

October 2001

October 2002

October 2003

October 2004

October 2005

68 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Figure 32. Cumulative change in volume of sediments of selected reaches of Fountain Creek near 

site 07103700 (FoCr_Manitou) and 07105800 (FoCr_Security), 1999 through 2005.

07103700 (FoCr_Manitou)

07105800 (FoCr_Security)

1999 2000 2001 2002 2003 2004 2005 2006

CUMULATIVE CHANGE IN REACH VOLUME, IN CUBIC FEET

0

2,000

4,000

6,000

8,000

10,000

12,000

DATE

1999 2000 2001 2002 2003 2004 2005 2006

CUMULATIVE CHANGE IN REACH VOLUME, IN CUBIC FEET –50,0000

–40,0000

–30,0000

–20,0000

–10,0000

0

Stream Morphology 69
2,200 ft3

 (fig. 32, table 12). Based on the probable range in 

bulk density of sand and gravel deposits and the net change in 

reach volume, 64.9 to 108 tons (table 12) has been deposited 

in this reach.

Surveys of the cross section at site 07105530 

(FoCr_Janitell) between July 2003 and July 2006 indicate 

downcutting as the dominant channel-forming process. 

Channel degradation ranged from 0.2 to 0.7 ft, and channel 

aggradation ranged from 0.1 to 0.25 ft. Between July 2003 

and July 2006, net channel downcutting was 1.28 ft. Between 

July 2003 and July 2006, cross-section area decreased 24.0 ft 

(table 11) as a result of downcutting. Based on the probable 

range in bulk density of sand and gravel deposits and the net 

change in cross-section area, approximately 0.72 to 1.2 tons 

(table 11) has been eroded from this cross section as a result of 

downcutting.

Cross-section surveys between October 1999 and 

October 2005 at site 07105800 (FoCr_Security) indicate 

downcutting as the dominant process at the three upstream 

cross sections and downcutting and channel widening as the 

dominant process at the two most downstream cross sections. 

Degradation at cross sections ranged from 0.11 to 0.85 ft 

(table 11). Between October 1999 and October 2005, net 

change in cross-section area ranged from 4.84 to –191 ft2

(table 11). Estimates of the net mass of material removed from 

the channel between October 1999 and October 2005 ranged 

from about 3,730 to 6,210 tons (table 12).

To evaluate the effects of wastewater treatment-plant 

effluent discharges on channel morphology, the MannWhitney test was used to evaluate changes in normal flow and 

particle-size distribution of bed material between the upstream 

site, 07105500 (FoCr_Nevada), and the downstream sites, 

07105530 (FoCr_Janitell) and 07105800 (FoCr_Security), 

of the Las Vegas Street Wastewater Treatment Plant. The 

Mann-Whitney test indicated a significant increase in median 

normal flow between site 07105500 (FoCr_Nevada) (34 ft3/s) 

and site 07105530 (FoCr_Janitell) (88 ft3/s). The MannWhitney test also indicated a significant difference in median 

particle size between the two sites: 4 mm at site 07105500 

(FoCr_Nevada) and 12 mm at site 07105530 (FoCr_Janitell). 

The increased streamflow, due to wastewater treatment-plant 

discharges downstream from site 07105500 (FoCr_Nevada), 

has increased the sediment transport capacity at site 07105530 

(FoCr_Janitell) (table 10) immediately downstream from 

the treatment plant. The increased transport capacity at 

site 07105530 (FoCr_Janitell) has resulted in greater transport 

of finer sediments and a shift in the median particle size of 

bed material from fine to medium gravel. The increase in 

transport capacity at site 07105530 (FoCr_Janitell) during 

normal flow appears to be limited to an undefined reach 

downstream from site 07105530 (FoCr_Janitell) and upstream 

from site 07105800 (FoCr_Security). This increase is because 

median particle sizes of bed material at site 07105500 

(FoCr_Nevada) and site 07105800 (FoCr_Security) both 

equal 4 mm, and the transport capacity based on the Shields 

equation at site 07105800 (FoCr_Security) is less than the 

transport competence at site 07105500 (FoCr_Nevada) 

(table 10).

Sand Creek

Channel morphology of Sand Creek (07105600) (SaCr) 

has only been monitored since October 2003. Cross-section 

surveys indicate channel infilling as the dominant process, 

with the channel aggrading 0.17 to 1.81 ft (fig. 33, table 11). 

Changes in cross-sectional sediment area ranged from 

–38.6 ft2 to –28.1 ft2 at the cross sections at the ends of the 

reach, and 165 ft2 to 204 ft2 at the inner three cross sections. 

The slope of the channel has decreased 0.00025, and the 

sediment volume increased 112,000 ft3 (table 12). Based on 

the probable range in bulk density of sand and gravel deposits 

and the net change in sediment volume, 3,360 to 5,600 tons 

(table 12) has been deposited in this reach.

Summary

In 1998, the U.S. Geological Survey, in cooperation 

with Colorado Springs City Engineering, began a study of the 

Fountain and Monument Creek watersheds to characterize 

water quality and suspended-sediment conditions in the 

watershed for different flow regimes, with an emphasis on 

characterizing water quality during storm runoff. Waterquality and suspended-sediment data collected from 1981 

through 2006 were used in the study. Water-quality data were 

collected at 11 sites between 1981 and 2001, and 14 tributary 

sites were added in 2003. Stream-water and sediment-quality 

samples were collected by the U.S. Geological Survey in 

the Fountain and Monument Creek watersheds from 1981 

through 2006 to evaluate the effects of stormflow. The mean 

annual precipitation from 1981 through 2001 was 18.5 

inches. The mean annual precipitation for the period 2001 

through 2006 decreased to 13.5 inches, primarily due to the 

2002 drought conditions; but even when 2002 was removed 

from the calculation of the mean, the Colorado Springs area 

received on average 14.5 inches of precipitation during the 

most recent period, similar to the recorded mean precipitation 

from 1949 through 1980. Between 1998 and 2006, the annual 

precipitation ranged from 7.8 inches in 2002 to 27.6 inches in 

1999, which represent the minimum and the maximum annual 

precipitation for the 52-year period of record.

Stormflow concentrations from 1998 through 2006 were 

compared to Colorado acute instream standards and, with the 

exception of a few isolated cases, did not exceed water-quality 

standards for inorganic constituents that were analyzed. In 

many cases water quality varied according to flow regime. The 

largest specific-conductance values occurred during base flow 

and, as a result of dilution, were smaller during stormflow. The 

largest increases in specific conductance occurred during base 

flow and normal flow between Fountain Creek sites 07103700 

(FoCr_Manitou) and 07103707 (FoCr_8th), upstream from 

70 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Figure 33. Change in minimum streambed altitude at cross sections along a reach of Sand Creek near site 07105600 

(SaCr), October 2003 through October 2005.

DISTANCE DOWNSTREAM, IN FEET FROM FIRST CROSS SECTION

0 200 400 600 800 1,000

ALTITUDE ABOVE AN ARBITRARY DATUM, IN FEET 76

78

80

82

84

86

88

90

October 2003

October 2004

October 2005

concentrations of E. coli were detected during periods of 

base flow and were largest during periods of stormflow. 

Median E. coli concentrations at main-stem sites during 

base flow were less than 100 col/100 mL, whereas median 

concentrations of E. coli during normal and stormflow 

conditions were much larger, ranging between 80 and 660 

col/100 mL during normal-flow conditions and 1,300 to 

17,000 col/100 mL during stormflow conditions.

Elevated concentrations of nitrite plus nitrate were 

measured at two sites on Cottonwood Creek, a tributary to 

Monument Creek: 07103985 (TbCo) and 07103990 

(lower_CoCr). During base-flow and normal-flow conditions, 

the median concentrations of nitrite plus nitrate ranged 

from 5.1 to 6.1 mg/L and were 4 to 7 times larger than 

concentrations at the nearest upstream site on Monument 

Creek, site 07103970. Median concentrations of total 

phosphorus in Fountain Creek upstream from the Monument 

Creek confluence tended to be larger during stormflow and 

smaller during base-flow and normal-flow conditions. 

Median total phosphorus concentrations at sites 07103970 

(MoCr_Woodmen) and 07104905 (MoCr_Bijou) during 

stormflow were 2.4 to 5.6 times larger than concentrations 

during base-flow and normal-flow conditions, respectively. 

the confluence with Monument Creek, which indicates a 

source of relatively large dissolved solids. Spatially, specific 

conductance tends to increase in a downstream direction. 

Specific conductance in Monument Creek and the tributaries 

draining to it ranged from less than 100 to more than 2,000 

μS/cm, during base-flow and normal-flow conditions. Median 

specific-conductance concentrations generally ranged from 

400 to 700 μS/cm.

Concentrations of biochemical oxygen demand 

measured over a 5-day period (BOD5) at all main-stem sites 

during 1998 through 2006 generally were larger during 

stormflow than during base flow and normal flow. Median 

BOD5 concentrations during stormflow ranged from 1.0 to 

10.3 milligrams per liter (mg/L) compared with a range of 

1.0 to 5.9 mg/L during base flow. Fecal coliform bacteria 

concentrations, during the period 1998 through 2006, were 

highly variable, generally ranging by more than a factor 

of 10 between flow regimes at each site. Fecal coliform 

concentrations tended to be largest during stormflow and 

smallest during base flow. Generally, median fecal coliform 

concentrations on Monument Creek along the main-stem 

were larger than 200 colonies per 100 milliliters (col/100 mL) 

during periods of normal flow and stormflow. The smallest 

Summary  71
Between sites 07105500 (FoCr_Nevada) and 07105530 

(FoCr_Janitell), during 1998 through 2006, median 

concentrations of dissolved nitrite plus nitrate, dissolved 

ammonia, and total phosphorus increased significantly 

downstream from the Las Vegas Street Wastewater Treatment 

Plant effluent outfall. The upstream to downstream increase 

was most pronounced during base-flow and normal-flow 

conditions but also was evident during stormflow conditions 

for all nutrients analyzed.

Large differences in median base-flow concentration in 

several trace elements were apparent between Fountain Creek 

sites 07103700 (FoCr_Manitou) and 07103707 (FoCr_8th), 

upstream from the confluence with Monument Creek. 

Concentrations of dissolved and total copper, total manganese, 

total nickel, dissolved and total selenium, and dissolved and 

total zinc ranged from 3 to 27 times larger at site 07103707 

(FoCr_8th) than at site 07103700 (FoCr_Manitou) during 

base flow, indicating a large source of trace elements between 

these two sites. The likely source area is Gold Hill Mesa, a 

former tailings pile for a gold refinery located just upstream 

from the confluence with Monument Creek, and upstream 

from site 07103707 (FoCr_8th). Median total selenium concentrations during base flow and normal flow increased from 

1.0 to 6.8 micrograms per liter (μg/L) and 0.50 to 4.0 μg/L, 

respectively, between sites 07103700 (FoCr_Manitou) and 

07103707 (FoCr_8th). Farther downstream in Fountain Creek, 

stormflow concentrations for total copper, lead, manganese, 

nickel, and zinc were larger at site 07105800 (FoCr_Security) 

than at site 07105530 (FoCr_Janitell), compared with other 

main-stem sites, and indicate a relatively large source of 

these metals between the two sites. Similar patterns for 

total copper, lead, nickel, and zinc were observed during the 

previous permit period, 1998 through 2002, indicating that the 

source area is still contributing trace metals downstream from 

site 07105530 (FoCr_Janitell), although in some cases median 

stormflow concentrations have declined slightly since 1998.

Instantaneous nutrient loads varied considerably 

from site to site during the period 1998 through 2006, and 

stormflow loads generally were considerably larger than 

during base-flow and normal-flow conditions. Loads increased 

downstream from the Fountain–Monument Creek confluence 

because of the combined flows from both creeks, but also, in 

some cases, because nutrient concentrations were larger in 

lower Fountain Creek than in upper Fountain or Monument 

Creeks. Large increases in nutrient loading were particularly 

noticeable downstream from the Nevada Street Wastewater 

Treatment Plant at site 07105530 (FoCr_Janitell). Nutrient 

loads increased between sites 07105500 (FoCr_Nevada) and 

07105530 (FoCr_Janitell), on average, more than 350 percent 

during stormflow conditions.

Loads of most dissolved and total trace elements 

increased between sites 07103970 (MoCr_Woodmen) and 

07104905 (MoCr_Bijou) during base-flow, normal-flow, 

and stormflow conditions. The load increase generally was 

between 2 and 4 times larger at the downstream site 07104905 

(MoCr_Bijou) during base-flow and normal-flow conditions 

but was larger during stormflow conditions when loads 

increased by 1.2 to 18 times.

Suspended-sediment concentrations, discharges, and 

yields associated with stormflow were significantly larger than 

those during normal flow. Significant temporal differences 

in median suspended-sediment concentration, discharge, and 

yield at a site generally coincided with a significant increase or 

decrease in median streamflow.

During normal flow, the uppermost location on 

Monument Creek, site 07103970 (MoCr_Woodmen), had the 

smallest median suspended-sediment concentrations. Cottonwood Creek had the largest median suspended-sediment 

concentrations during normal flow. Suspended-sediment 

concentrations during normal flow at sites downstream from 

Cottonwood Creek were not significantly different from one 

another. Suspended-sediment concentrations during stormflow 

generally increased in a downstream order for main-stem sites 

on Fountain and Monument Creeks. The largest suspendedsediment concentrations during stormflow were measured on 

Cottonwood Creek.

Suspended-sediment discharge during normal flow varied 

by site, generally increasing from upstream to downstream 

as streamflow increased. Suspended-sediment discharge of 

Cottonwood Creek at site 07103990 (lower_CoCr) ranged 

from 3 to 10 tons per day (tons/d) and represented a significant 

fraction of the suspended-sediment discharge of Monument 

Creek at site 07104905 (MoCr_Bijou) during normal flow. 

Suspended-sediment discharge ranged from 0.5 to 10 tons/d 

at the most upstream site on Monument Creek (07103970, 

MoCr_Woodmen) and ranged from 25 to 180 tons/d at the 

most downstream site on Fountain Creek (07105800, 

FoCr_Security).

During stormflow, suspended-sediment discharge increased in a downstream order, ranging from 20 to 250 tons/d 

at the most upstream site (07103970, MoCr_Woodmen) and 

ranging from 700 to 4,000 tons/d at the most downstream 

site (07105800, FoCr_Security). Suspended-sediment 

discharge during stormflow did not always increase as 

drainage area increased. Suspended-sediment discharge at 

Cottonwood Creek, with a drainage area of about 18.7 mi2, 

was almost 2 times larger than suspended-sediment discharge 

at site 07103970 (MoCr_Woodmen), with a drainage area of 

about 180 mi2. Suspended-sediment discharge of Cottonwood 

Creek during stormflow generally was larger than suspendedsediment discharge of Sand Creek.

Total cumulative daily suspended-sediment discharges 

increased from upstream to downstream sites and varied from 

year to year, largest in 1999 and smallest in 2002. Suspendedsediment discharges of Cottonwood Creek, site 07103990 

(lower_CoCr), were generally larger than suspended-sediment 

discharges at site 07103970 (MoCr_Woodmen), despite the 

larger drainage area at site 07103970. An evaluation of relative 

contribution of suspended-sediment discharge at site 07103990 

(lower_CoCr) to downstream sites indicated that suspendedsediment discharge from 07103990 (lower_CoCr) represented 

18 to 30 percent of suspended-sediment discharge at 

72 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
site 07104905 (MoCr_Bijou). Suspended-sediment discharge 

at site 07103970 (MoCr_Woodmen) represented 13 to 

18 percent of suspended-sediment discharge at site 07104905 

(MoCr_Bijou). Suspended-sediment discharge at 

site 07103970 (MoCr_Woodmen) and 07103990 (lower_CoCr) 

accounted for only about 35 to 45 percent of suspendedsediment discharge at site 07104905 (MoCr_Bijou), indicating 

that additional sources of suspended-sediment discharge 

exist between sites 07103970 (MoCr_Woodmen), 07103990 

(lower_CoCr) and 07104905 (MoCr_Bijou). Suspendedsediment discharge at site 07104905 (MoCr_Bijou) 

generally was similar to suspended-sediment discharges at 

site 07105500 (FoCr_Nevada). The relative contribution of 

suspended-sediment discharge at site 07104905 (MoCr_Bijou) 

to suspended-sediment discharge at site 07105500 

(FoCr_Nevada) ranged from 68 to 98 percent. Suspendedsediment discharge at site 07105500 (FoCr_Nevada) generally 

represented about 70 percent of suspended-sediment discharge 

at site 07105800 (FoCr_Security). Relative contributions of 

suspended-sediment discharge from site 07105600 (SaCr) to 

site 07105800 (FoCr_Security) ranged from 23 to 37 percent.

Suspended-sediment yields provide a means for 

identifying source contribution areas. The smallest yields 

were computed at site 07103970 (MoCr_Woodmen) (drainage 

area of 180 mi2). Site 07103990 (lower_CoCr) (drainage 

area of 18.7 mi2) had the largest suspended-sediment 

yields. Suspended-sediment yields increased progressively 

from site 07103970 (MoCr_Woodmen) to site 07105800 

(FoCr_Security) during normal flow and stormflow as 

drainage area increased. Suspended-sediment yields vary 

by more than an order of magnitude during normal flow 

but generally are small. Although large spatial variations in 

suspended-sediment yields occurred during normal flows, 

the suspended-sediment yields that were associated with 

stormflow generally were more than 10 times larger than the 

suspended-sediment yields that occurred during normal flow.

Instantaneous suspended-sediment concentration samples 

were collected at selected ungaged tributaries to better 

characterize the spatial variability of suspended sediment in 

the Fountain and Monument Creek watersheds. Suspendedsediment concentrations during normal flow and stormflow 

varied considerably at individual sites and spatially between 

sites. Sites on streams in the Colorado Piedmont and draining 

to Fountain and Monument Creeks from the east generally 

had larger suspended-sediment concentrations than sites on 

streams in the Colorado Piedmont and Southern Colorado 

Rocky Mountains physiographic regions and draining to 

Fountain and Monument Creeks from the west. The largest 

concentrations were measured in Kettle Creek, Cottonwood 

Creek, and Sand Creek, which drain the Colorado Piedmont 

from the east of Fountain and Monument Creeks, and 

North Rockrimmon Creek, which drains the Colorado 

Piedmont from the west of Monument Creek. Suspendedsediment concentrations during stormflow at sites that drain 

the Colorado Piedmont ranged from about 800 to about 

60,000 mg/L. Suspended-sediment concentrations during 

stormflow at sites that drain the Southern Rocky Mountains 

physiographic province (Bear Creek sites 07105000 

and 384909104504401) ranged from about 10 to about 

1,000 mg/L. Suspended-sediment discharge ranged from 

less than 10 tons/d at sites on streams that drain to Fountain 

and Monument Creeks from the west and ranged from 1,000 

and 10,000 tons/d at sites on streams that drain to Fountain 

and Monument Creeks from the east. Suspended-sediment 

yields varied less spatially, generally ranging from 10 to 

100 tons/d/mi2.

Analysis of the sediment transport capacity for Fountain 

and Monument Creeks and Kettle, Cottonwood, and Bear 

Creek tributaries indicated that minimum streamflows at all 

sites generally have the capacity to transport coarse to very 

coarse sands. Higher flows have the capacity to transport 

coarse gravel. Transport of cobble-size bed material is 

possible at the largest measured flows at sites 07103700 

(FoCr_Manitou), 07103990 (lower_CoCr), 07105000 

(upper_BeCr), and 07105500 (FoCr_Nevada). Periodic 

surveys of channel cross-section geometry indicate that 

channel downcutting is the predominant channel-forming 

process in the Fountain Creek watershed. Episodes of channel 

degradation and aggradation have occurred at most sites 

surveyed between 1999 and 2005. Estimates of changes 

in volume of sediments of surveyed reaches ranged from 

–2,200 ft3 at site 07103977 (upper_CoCr) to 124,000 ft3 at 

site 07105800 (FoCr_Security). Estimated mass of eroded 

bed and bank material from surveyed reaches between 

1999 and 2005 varied from 64.9 to 6,210 tons. Wastewater 

treatment-plant discharges increased streamflows and 

resulted in increased sediment transport capacity immediately 

downstream from the wastewater treatment plant. The 

increased sediment transport capacity has resulted in a shift 

in the median particle size of bed material from fine gravel 

upstream from the wastewater treatment plant to medium 

gravel immediately downstream from the wastewater treatment 

plant.

References Cited

Anderson, Keith E., 1973, Water well handbook: St. Louis, 

Missouri Water Well & Pump Contractors Association., 

Inc., Scholin Brothers Printing Company.

Buchanan, T.J., and Somers, W.P., 1968, Stage measurement 

at gaging stations: U.S. Geological Survey Techniques of 

Water-Resources Investigations, book 3, chap. A7, 28 p.

Carter, R.W., and Davidian, Jacob, 1968, General procedure 

for gaging streams: U.S. Geological Survey Techniques of 

Water-Resources Investigations, book 3, chap. A6, 13 p.

References Cited  73
City of Colorado Springs, 1997, Municipal stormwater 

discharge permit, Information available on the Web, 

accessed May 25, 2007, at http://www.springsgov.com/Page.

asp?NavID=139&Print=True

Colorado Department of Public Health and Environment, 

2001a, Standards and methodologies for surface water, 

5 CCR 1002–31: Colorado Department of Public Health 

and Environment, Water Quality Control Commission, 

various pagination.

Colorado Department of Public Health and Environment, 

2001b, Regulation no. 32, Classifications and numeric 

standards for Arkansas River Basin: Colorado Department 

of Public Health and Environment, Water Quality Control 

Commission, various pagination.

Colorado Department of Public Health and Environment, 2003, Voluntary clean-up and redevelopment 

program, Information available on the Web, accessed 

May 1, 2007, at http://198.187.128.12/colorado/1pext.

dll?f=templates&fn=fs-main.htm&2.0.

Colorado Department of Public Health and Environment, 

2006, Water Quality Control Commission Regulations, 

Surface Water Quality Classifications and Standards, Information available on the Web, accessed May 25, 2007, at 

http://www.cdphe.state.co.us/regulations/wqccregs/

Crowfoot, R.M., Bruce, N.L., Unruh, J.W., Ritz, G.F., Steger, 

R.D., and O’Neill, G.B., 1999, Water resources data Colorado, water year 1998, Volume 1. Missouri River Basin, 

Arkansas River Basin, and Rio Grande Basin: U.S. Geological Survey Water-Data Report CO–98–1, 451 p.

Crowfoot, R.M., Unruh, J.W., Ritz, G.F., Steger, R.D., and 

O’Neill, G.B., 2000, Water resources data Colorado, water 

year 1999, Volume 1. Missouri River Basin, Arkansas River 

Basin, and Rio Grande Basin: U.S. Geological Survey 

Water-Data Report CO–99–1, 499 p.

Crowfoot, R.M., Unruh, J.W., Ritz, G.F., Steger, R.D., and 

O’Neill, G.B., 2001, Water resources data Colorado, water 

year 2000, Volume 1. Missouri River Basin, Arkansas River 

Basin, and Rio Grande Basin: U.S. Geological Survey 

Water-Data Report CO–00–1, 498 p.

Crowfoot, R.M., Steger, R.D., Payne, W.F., and O’Neill, G.B., 

2002, Water resources data Colorado, water year 2001, 

Volume 1. Missouri River Basin, Arkansas River Basin, 

and Rio Grande Basin: U.S. Geological Survey Water-Data 

Report CO–01–1, 539 p.

Crowfoot, R.M., Payne, W.F., and O’Neill, G.B., 2003, Water 

resources data Colorado, water year 2002, Volume 1. Missouri River Basin, Arkansas River Basin, and Rio Grande 

Basin: U.S. Geological Survey Water-Data Report 

CO–02–1, 609 p.

Crowfoot, R.M., Payne, W.F., and O’Neill, G.B., 2004, Water 

resources data Colorado, water year 2003, Volume 1. Missouri River Basin, Arkansas River Basin, and Rio Grande 

Basin: U.S. Geological Survey Water-Data Report 

CO–03–1, 577 p.

Crowfoot, R.M., Payne, W.F., O’Neill, G.B., Boulger, R.W., 

and Sullivan, J.R., 2005, Water resources data Colorado, 

water year 2004, Volume 1. Missouri River Basin, Arkansas 

River Basin, and Rio Grande Basin: U.S. Geological Survey 

Water-Data Report CO–04–1, 379 p.

Crowfoot, R.M., Payne, W.F., O’Neill, G.B., and Boulger, 

R.W., 2006, Water resources data Colorado, water year 

2005, Information available on the Web, accessed May 11, 

2007, at http://web10capp.er.usgs.gov/adr_lookup/wdr-co05/index.jsp

Dunne, Thomas, and Leopold, L.B., 1978, Water in environmental planning: New York, W.H. Freeman and Company, 

818 p.

Edelmann, Patrick, Ferguson, S.A., Stogner, R.W., Sr., August, 

M., Payne, W.F., and Bruce, J.F., 2002, Evaluation of water 

quality, suspended sediment, and stream morphology with 

an emphasis on effects of storm flow on Fountain and 

Monument Creek basins, Colorado Springs and vicinity, 

Colorado, 1981 through 2001: U.S. Geological Survey 

Water-Resources Investigations Report 2002–4104, 59 p.

Edwards, T.K., and Glysson, G.D., 1988, Field methods for 

measurement of fluvial sediment: U.S. Geological Survey 

Open-File Report 86–531, 117 p.

Elliott, J.G., Kircher, J.E., and von Guerard, Paul, 1984, Sediment transport in the lower Yampa River, northwestern 

Colorado: U.S. Geological Survey Water-Resources Investigations Report 84–4141, 44 p.

Environmental Systems Research Institute, Inc., 1982–2005, 

Arc/Info version 9.1.

Environmental Systems Research Institute, Inc., 1999–2005, 

Arc/Map version 9.1.

Gordon, Nancy D., McMahon, Thomas A., Finlayson, Brian 

L., Gippel, Christopher J., and Nathan, Rory J., 2004, 

Stream hydrology, an introduction for ecologists: West Sussex, John Wiley and Sons, Ltd., 429 p.

Hansen, W.R., and Crosby, E.J., 1982, Environmental geology 

of the Front Range urban corridor and vicinity, Colorado 

with a specific section on Physical properties and performance characteristics of surficial deposits and rock units in 

the greater Denver area by R.R. Shroba: U.S. Geological 

Survey Professional Paper 1230, 99 p.

74  Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Harrelson, C.C., Rawlins, C.L., and Potyondy, J.P., 1994, 

Stream channel reference sites–An illustrated guide to field 

technique, General Technical Report RM-245: Fort Collins, Colo., U.S. Department of Agriculture, Forest Service, 

Rocky Mountain Forest and Range Experiment Station, 

61 p.

Helsel, D.R., and Hirsch, R.M., 1992 Statistical methods in 

water resources: New York, Elsevier Science Publishing 

Company Inc., 522 p.

Horowitz, A.J., Demas, C.R., Fitzgerald, K.K., Miller, T.L., 

and Rickert, D.A., 1994, U.S. Geological Survey protocol 

for the collection and processing of surface-water samples 

for the subsequent determination of inorganic constituents 

in filtered water: U.S. Geological Survey Open-File Report 

94–539, 57 p.

Karlinger, M.R., Eschner, T.R., Hadley, R.F., and Kircher, J.E., 

1983, Relation of channel-width maintenance to sediment 

transport and river morphology—Platte River, south-central Nebraska: U.S. Geological Survey Professional Paper 

1277–E, 19 p.

Kennedy, E.J., 1983, Computation of continuous records of 

streamflow: U.S. Geological Survey Techniques of WaterResources Investigations, book 3, chap. A13, 53 p.

Kennedy, E.J., 1984, Discharge ratings at gaging stations: U.S. 

Geological Survey Techniques of Water-Resources Investigations, book 3, chap. A10, 59 p.

Kennedy, E.J., 1990, Levels at streamflow gaging stations: 

U.S. Geological Survey Techniques of Water-Resources 

Investigations, book 3, chap. A19, 27 p.

Koltun, G.F., Eberle, M., Gray, J.R., Glysson, G.D., 2006, 

User’s manual for the Graphical Constituent Loading Analysis System (GCLAS): U.S. Geological Survey Techniques 

and Methods 4–C1, 51 p.

Koltun, G.F., Gray, J.R., and McElhone, T.J., 1994, Users 

manual for DECALC, a computer program for computation 

of suspended-sediment discharge: U.S. Geological Survey 

Open-File Report 94–459, 46 p.

Larsen, L.S., 1981, Soil survey of El Paso County area, Colorado: Washington D.C., U.S. Department of Agriculture, 

Soil Conservation Service, 212 p.

Leopold, L.B., Wolman, M.G., and Miller, J.P., 1964, Fluvial 

processes in geomorphology: New York, Dover Publications, Inc., 522 p.

Meade, Robert H., 1985, Wavelike movement of bedload sediment, East Fork River, Wyoming: Environmental Geology, 

v. 7, no. 4, p. 215–225.

National Water Information System, 2007, Information 

available on the Web, accessed April 12, 2007, at http://

waterdata.usgs.gov/co/nwis

Pikes Peak Area Council of Governments, 2005, Fountain 

Creek Watershed, Impervious surface area and watershed 

health analysis, accessed April 8, 2007, at http://www.

fountain-crk.org/Reports/impervious%20surface%20report.

htm

Rowland, R.C., Stephens, D.W., Waddell, B., and Naftz, D.L., 

2003, Selenium contamination and remediation at Stewart Lake Waterfowl Management Area and Ashley Creek, 

Middle Green River Basin, Utah: U.S. Geological Survey 

Fact Sheet 031–03, 6 p.

Schumm, S.A., 1977, The effluvial system: New York, John 

Wiley and Sons, 338 p.

Seiler, R.L., Skorupa, J.P., and Peltz, L.A., 1999, Areas susceptible to irrigation-induced selenium contamination of 

water and biota in the western United States: U.S. Geological Survey Circular 1180, 36 p.

Shelton, Theodore, 1991, Interpreting drinking water quality 

analysis—What do the numbers mean?: New Brunswick, 

N.J., Rutgers Cooperative Extension, 58 p.

Stogner, R.W., Sr., 2000, Trends in precipitation and streamflow and changes in stream morphology in the Fountain 

Creek watershed, Colorado, 1939–99: U.S. Geological 

Survey Water-Resources Investigations Report 2000–4130, 

43 p.

Sylvester, M.A., Kister, L.R., and Garrett, W.B., eds., 1990, 

Guidelines for the collection, treatment, and analysis of 

water samples, U.S. Geological Survey Western Region 

field manual: Unpublished report on file in the Pueblo, 

Colo., Water Resources Discipline Office of the U.S. Geological Survey, 144 p.

The Gazette, Colorado Springs, 2006, Colorado Springs in 

perspective: Information available on the Web, accessed 

March 27, 2007, at http://www2.gazette.com/advertise/

market.html

University of Wisconsin–Extension, 1997, Polluted urban 

runoff—A source of concern: Information available on the 

Web, accessed March 12, 2007, at http://clean-water.uwex.

edu/pubs/pdf/storm.urban.pdf

U.S. Census Bureau, 2007, Population Finder, Information 

available on the Web, accessed May 3, 2007, at http://

factfinder.census.gov/servlet/SAFFPopulation?_

event=Search&_name=el+paso&_state=04000US08&_

county=el+paso&_cityTown=el+paso&_zip=&_sse=on&_

lang=en&pctxt=fph

References Cited  75
U.S. Environmental Protection Agency, 1986, Ambient water 

quality criteria for bacteria, 1986: Washington, D.C., U.S. 

Environmental Protection Agency, Office of Water Regulations and Standards, EPA/440/5–84–002. Office of Water 

Regulations and Standards.

U.S. Environmental Protection Agency, 1992, Guidance 

manual for the preparation of part 1 of the NPDES permit 

applications for discharges from municipal separate storm 

sewer systems: U.S. Environmental Protection Agency, 

Office of Water, EPA 505/8–91–003A, various pagination.

U.S. Environmental Protection Agency, 2004, Monitoring and 

assessing water quality, chapter 5.11, fecal bacteria: Information available on the Web, accessed March 12, 2007, at 

http://www.epa.gov/OWOW/monitoring/volunteer/stream/

vms511.html

U.S. Geological Survey, 1977, National handbook of recommended methods for water-data acquisition: Reston, Va.: 

U.S. Geological Survey monograph, Office of Water Data 

Coordination, various pagination.

von Guerard, Paul, 1989a, Suspended sediment and sedimentsource areas in the Fountain Creek drainage basin upstream 

from Widefield, southeastern Colorado: U.S. Geological 

Survey Water-Resources Investigations Report 88–4136, 

36 p.

von Guerard, Paul, 1989b, Sediment-transport characteristics 

and effects of sediment transport on benthic invertebrates in 

the Fountain Creek drainage basin upstream from Widefield, southeastern Colorado 1985–88: U.S. Geological Survey Water-Resources Investigations Report 88–4161, 133 p.

Wahl, K.L., and Wahl, T.L., 1995, Determining the flow of 

Comal Springs at new Braunfels, Texas: Texas Water 95, 

American Society of Civil Engineers, August 16–17, 1995, 

San Antonio, Texas, p. 77–86.

Wilde, F.D., Radtke, D.B., Gibs, J., and Iwatsubo, R.T., eds., 

1998, National field manual for collection of water-quality data: U.S. Geological Survey Techniques of WaterResources Investigations, book 9, chap. A6, various pagination.

Wolman, M.G., 1954, A method of sampling coarse river-bed 

material: Transactions of the American Geophysical Union, 

v. 35, no. 6, p. 951–956.

Wolman, M.G., and Miller, J.P., 1960, Magnitude and frequency of forces in geomorphic process: Journal of Geology, v 68, no. 1, p.54–74.

World Health Organization, 1996, Trace elements in human 

nutrition and health: World Health Organization, Geneva, 

Switzerland, 361 p.

76 Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006
Prepared by the Helena Publishing Service Center

For additional information contact:

Director, Colorado Water Science Center

U.S. Geological Survey

Box 25046, MS 415

Denver Federal Center

Lakewood, Colorado 80225

(303) 236-5900

http://co.water.usgs.gov/
Mau and others—Stormflows and Wastewater Treatment-Plant Effluent Discharges, Colorado Springs, Colorado, 1981–2006—SIR 2007–5104

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