U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2010–5198

Prepared in cooperation with the Colorado Water Conservation Board, Colorado River Water 

Conservation District, Upper Colorado River Endangered Fish Recovery Program, Colorado 

Division of Water Resources, and City of Craig

Streamflow Gain-Loss Characteristics of Elkhead Creek 

Downstream from Elkhead Reservoir near Craig, Colorado, 

2009
Cover Photographs:

Top left photo: Outlet works at Elkhead Reservoir near Craig, Colorado. Photo taken by Barbara C. Ruddy, U.S. 

Geological Survey, September 5, 2008.

Middle photo: Looking downstream on Elkhead Creek near discontinued streamflow-gaging station 09246400, 

Elkhead Creek below Maynard Gulch near Craig, Colorado. Photo taken by Barbara C. Ruddy, U.S. Geological 

Survey, September 5, 2008.

Bottom right photo: Hydrographer Kevin Murphy making a streamflow measurement at streamflow-gaging 

station 09246500, Elkhead Creek near Craig, Colorado. Photo taken by Barbara C. Ruddy, U.S. Geological Survey, 

September 5, 2008.
Streamflow Gain-Loss Characteristics of 

Elkhead Creek Downstream from Elkhead 

Reservoir near Craig, Colorado, 2009

By Barbara C. Ruddy

Prepared in cooperation with the Colorado Water Conservation Board, Colorado 

River Water Conservation District, Upper Colorado River Endangered Fish 

Recovery Program, Colorado Division of Water Resources, and City of Craig

Scientific Investigations Report 2010–5198

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

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

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Ruddy, B.C., 2010, Streamflow gain-loss characteristics of Elkhead Creek downstream from Elkhead Reservoir near 

Craig, Colorado, 2009: U.S. Geological Survey Scientific Investigations Report 2010–5198, 14 p.
iii

Contents

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

Introduction.....................................................................................................................................................1

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

Description of Study Area ...................................................................................................................3

Methods...........................................................................................................................................................4

Description of Measurement Sites....................................................................................................4

Streamflow data....................................................................................................................................5

Elkhead Reservoir Releases ......................................................................................................5

Streamflow-Gaging Station 09246500.......................................................................................5

Norvell Ditch.................................................................................................................................6

Streamflow Characteristics of Elkhead Creek..........................................................................................6

Instantaneous Measurement Analysis .............................................................................................6

Water Volume Comparisons ...............................................................................................................8

Traveltime.............................................................................................................................................10

Summary........................................................................................................................................................10

Acknowledgments.......................................................................................................................................13

References Cited..........................................................................................................................................13

Figures

1. Map showing location of Elkhead Creek study area and measurement sites 

downstream from Elkhead Reservoir near Craig, Colorado ..........................................................2

2–4. Graphs showing:

 2. Instantaneous streamflow measurements at selected sites, August 5, 

October 3, and November 5, 2009...............................................................................................7

 3. Instantaneous streamflow measurements at selected sites, 

August–September 2009 ..............................................................................................................8

 4. Instantaneous and continuous record of streamflow downstream from 

Elkhead Reservoir, August 1 to October 4, 2009.....................................................................10

Tables

1. Location of streamflow measurement sites downstream from Elkhead 

Reservoir near Craig, Colorado ..................................................................................................5

2. Instantaneous streamflow measurements, August 5–November 5, 2009...........................7

3. Volume of water released from Elkhead Reservoir, August 1 to October 4, 2009..............9

4. Traveltime after a change in flow release from just downstream from the 

dam to station 09246500 Elkhead Creek near Craig, CO, August–September 2009 .........11
iv

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 0.004047 square kilometer (km2)

square mile (mi2) 259.0 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2) 

Volume

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

Flow rate

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

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).

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

ABBREVIATIONS

ADV Acoustic Doppler Velocimeter

CODWR Colorado Department of Water Resources

CWCB Colorado Water Conservation Board

CRWCD Colorado River Water Conservation District

SCADA Supervisory Control and Data Acquisition

USGS U.S. Geological Survey

UCREFRP Upper Colorado River Endangered Fish Recovery Program

WY Water year—A continuous 12-month period representing an annual 

hydrologic cycle selected to present data relative to hydrologic or 

meteorological phenomena. The water year used by the U.S. Geological 

Survey runs from October 1 through September 30 and is designated by 

the year in which it ends.
Abstract

The U.S. Geological Survey (USGS), in cooperation with 

the Colorado Water Conservation Board, the Upper Colorado 

River Endangered Fish Recovery Program (UCREFRP), 

Colorado Division of Water Resources, and City of Craig studied the gain-loss characteristics of Elkhead Creek downstream 

from Elkhead Reservoir to the confluence with the Yampa 

River during August through October 2009. Earlier qualitative 

interpretation of streamflow data downstream from the reservoir indicated that there could be a transit loss of nearly 10 

percent. This potential loss could be a significant portion of 

the releases from Elkhead Reservoir requested by UCREFRP 

during late summer and early fall for improving critical habitat 

for endangered fish downstream in the Yampa River. Information on the gain-loss characteristics was needed for the effective management of the reservoir releases.

In order to determine streamflow gain-loss characteristics 

for Elkhead Creek, eight measurement sets were made at four 

strategic instream sites and at one diversion from August to 

early October 2009. An additional measurement set was made 

after the study period during low-flow conditions in November 

2009. Streamflow measurements were made using an Acoustic 

Doppler Velocimeter to provide high accuracy and consistency, especially at low flows. During this study, streamflow 

ranged from about 5 cubic feet per second up to more than 

90 cubic feet per second with step increments in between. 

Measurements were made at least 24 hours after a change in 

reservoir release (streamflow) during steady-state conditions.

The instantaneous streamflow measurements and the 

streamflow volume comparisons show the reach of Elkhead 

Creek immediately downstream from Elkhead Reservoir to 

the streamflow-gaging station 09246500, Elkhead Creek near 

Craig, CO, is neither a gaining nor losing reach. The instantaneous measurements immediately downstream from the dam 

and the combined measurements of Norvell ditch plus streamflow-gaging station 09246500 are mostly within the plus or 

minus 5-percent measurement error of each other. The variability of data is such that sometimes the streamflow is greater 

upstream than downstream and sometimes the streamflow is 

greater downstream than upstream. Streamflow volumes were 

calculated for multiple time periods as determined by a change 

in release from the reservoir. Streamflow volumes were greater 

downstream than upstream for all but one time period. The 

predominance of greater streamflows downstream is due to 

the difference between the USGS instantaneous measurements 

and record computation with the Supervisory Control and 

Data Acquisition (SCADA) record at the dam. Immediately 

following an increase in streamflow from the reservoir, the 

downstream volume was smaller than the upstream volume, 

but this was an artifact of the traveltime between the two sites 

and possibly small amounts of water entering the streambank. 

Traveltimes were shorter at higher streamflows and when 

streamflow was increasing. 

Introduction

Elkhead Reservoir, northeast of Craig, Colo. (fig. 1), 

provides supplemental streamflow to the Yampa River to support increased water-supply needs including cooling water for 

a power-generating station at Craig, maintenance of minimum 

streamflows within critical habitat reaches for endangered fish, 

and diversion and withdrawal of streamflow for agricultural, 

domestic, and municipal uses.

Elkhead Reservoir, which was constructed in 1974, was 

enlarged in 2006 to provide water for the endangered fishes in 

the Yampa River and future water needs in the Yampa River 

basin (Colorado River Water Conservation District, 2010). 

Water storage resumed in November 2007. The Colorado 

Water Conservation Board (CWCB) acquired 5,000 acre-ft 

of storage to be used for the Upper Colorado River Endangered Fish Recovery Program (UCREFRP) to augment base 

flows through critical habitat reaches for endangered fish. The 

storage needs to be managed effectively to ensure that the 

reservoir releases are adequate to meet the downstream needs 

and are delivered at the proper time. Information on transit 

loss and traveltime for reservoir releases is needed to effectively manage the river for the endangered fish recovery and 

management and to address the needs of all river users. 

Streamflow Gain-Loss Characteristics of Elkhead Creek 

Downstream from Elkhead Reservoir near Craig, Colorado, 

2009

By Barbara C. Ruddy
2 Streamflow Gain-Loss Characteristics of Elkhead Creek Downstream from Elkhead Reservoir near Craig, Colorado

09244490

09246500

Smith ditch

Norvell ditch

Frentress pump 1 ID 1962

Starr irrigation ditch ID 770

Starr irrigation ditch Alt Pt ID 1188

Frentress pump 1 Ap ID 803

Vaughan pump

107°26'W 107°25'W 107°24'W 107°23'W

40°33'N

40°32'N

40°31'N

Base from U.S. Geological Survey digital data, 2007

09246400

Elkhead

Reservoir

Yampa River

0

0

0.5 1 MILE

0.5 1 KILOMETER

Craig

Pueblo

DENVER

Grand Junction

COLORADO

Measurement site immediately 

 downstream from dam

Measurement site at 

 confluence with Yampa

Study area

2

1

3

4

5

Elkhead River Ranch 

pump diversion

Elkhead

Creek

Maynard Gulch

09244490

2 Measurement site number

EXPLANATION

Perennial streams

Intermittent streams

Streamflow-gaging station and number

Diversion location and name

40

Figure 1. Location of Elkhead Creek study area and measurement sites downstream from Elkhead Reservoir near Craig, 

Colorado.
Introduction 3

The U.S. Geological Survey (USGS), in cooperation with 

the Colorado Water Conservation Board, the Upper Colorado 

River Endangered Fish Recovery Program (UCREFRP), 

Colorado Division of Water Resources, and City of Craig studied the gain-loss characteristics of Elkhead Creek downstream 

from Elkhead Reservoir to the confluence with the Yampa 

River during August through October 2009. Earlier qualitative interpretation of streamflow data downstream from the 

reservoir indicated that there could be a transit loss of nearly 

10 percent (Ray Tenney, Colorado River Water Conservation 

District, oral commun., 2007). This potential loss could be 

a significant portion of the releases from Elkhead Reservoir 

requested by UCREFRP during late summer and early fall for 

improving critical habitat for endangered fish downstream in 

the Yampa River.

Purpose and Scope

This report describes the streamflow gain-loss characteristics of Elkhead Creek near Craig, Colorado. The methodology, data, and the results of a streamflow gain-loss study and 

time of travel determination for Elkhead Creek downstream 

from Elkhead Reservoir to its confluence with the Yampa 

River are presented. Additionally, the report describes instantaneous streamflow data collected during August 5 through 

October 1, 2009, the analysis of streamflow record from 

August 1–October 4, 2009, and the comparative analysis of 

the discharge records from the reservoir and the streamflowgaging station 09246500, near the crossing of U.S. Highway 

40.

Description of Study Area

Elkhead Creek is a large, perennial tributary of the Yampa 

River upstream from Craig in northwestern Colorado. The 

study area is the approximate 9-mi reach of Elkhead Creek 

downstream from Elkhead Reservoir to the confluence with 

the Yampa River (fig. 1). The Elkhead watershed has an area 

of about 223 mi2. The headwaters originate in the Elkhead 

Mountains at an elevation of about 10,500 ft (not shown in 

figure 1 but approximately 3–10 mi north of the study area) 

(Kuhn and others, 2003). Mean basin slope is 18.6 percent 

(U.S. Geological Survey, 2010b). Creek elevations range from 

6,298 ft from just downstream from the dam to 6,220 ft at the 

confluence of the Yampa River. 

Downstream from the reservoir, Elkhead Creek is a 

meandering stream that flows over shales and sandstones of 

the Upper Cretaceous Lance Formation (Tweto, 1976) and 

Holocene alluvium. There are oxbow ponds and highly incised 

meanders with adjacent cottonwood groves. The streambed 

is composed of gravel and cobbles with some sandy streambanks and point bars. Valley-fill material is exposed in some 

cut banks where the gravel and sand strata are overlain by 

loamy deposits. The adjacent valley floor has been used for 

grazing and hay production since the late 19th century (Elliott 

and Gyetvai, 1999). Cottonwood trees, willows, other woody 

shrubs, and native grasses dominate the riparian vegetation.

Annual precipitation in the study area is about 15–17 

inches, but increases to more than 35 inches in the Elkhead 

Mountains (DiLuzio, 2007). The mean annual precipitation for 

the entire basin is 26 inches based on the 30-year average from 

1971 to 2000 (U.S. Geological Survey, 2010b). Most winter 

precipitation is in the form of snow in the Elkhead Mountains, 

and most Elkhead Creek streamflow is from snowmelt runoff. 

The highest streamflows usually occur during late April to 

late May during snowmelt runoff. At streamflow-gaging station 09246400 Elkhead Creek below Maynard Gulch near 

Craig, CO (discontinued), located 5.7 mi upstream from the 

confluence with the Yampa River, the streamflow peak was 

measured at 2,510 ft3/s on May 20, 2008. At streamflowgaging stations 09246500, Elkhead Creek near Craig, CO, and 

located 0.81 mi upstream from the confluence with the Yampa 

River, the streamflow peak was measured at 1,610 ft3/s on 

May 8, 2009. The 09246500 gage records runoff from nearly 

all of the watershed (U.S. Geological Survey, 2010b). Summer thunderstorms occur but are scattered and provide little 

runoff. Streamflow in the study area is regulated by releases 

from Elkhead Reservoir and is affected by multiple irrigation diversions (Kathy Bower, Colorado Department of Water 

Resources, written commun., 2010). During May through 

June, there may be as many as five active diversions. From 

June through early November, only the Norvell ditch, with 

senior water rights, diverts water from the creek. 

Elkhead Reservoir was constructed in 1974 by the 

Colorado Division of Wildlife (Colorado River Water Conservation District, 2010). Originally, it was designed with an 

embankment height of 80 ft to hold 13,700 acre-ft of water. 

Most of the water (8,310 acre-ft) was allocated as cooling 

water for the Craig coal-fired powerplant and the remaining 5,390 acre-ft was allocated as a recreation pool. In 2007, 

Elkhead Reservoir was enlarged to store and release water for 

the endangered fishes in the Yampa River during low flows in 

late summer and for future water needs in the Yampa River 

basin. The dam height was increased to 105 ft to provide 

an additional 11,750 acre-ft of reservoir storage (Colorado 

River Water Conservation District, 2010). The UCREFRP 

funded 5,000 acre-ft of the increase for the endangered fishes 

in the Yampa River. These fishes include the Colorado pike 

minnow, bonytail, razorback sucker, and humpback chub. 

Colorado River Water Conservation District (CRWCD) funded 

the additional 6,750 acre-ft for future water needs including 

2,000 acre-ft to be leased to the UCREFRP as more water for 

fish flows (Colorado River Water Conservation District, 2010).

The reservoir releases are monitored by CRWCD but the 

actual releases are made by the City of Craig (Ray Tenney, 

Colorado River Water Conservation District, oral commun., 

2010). Operationally, the reservoir is kept near maximum 

capacity; the outflow is kept similar to the gaged inflow at 

station 09246200 Elkhead Creek above Long Gulch near 

Hayden, CO (“flow-through” operation) (not shown in figure 1 

but about 10.6 mi upstream from Elkhead Dam). Operations 
4 Streamflow Gain-Loss Characteristics of Elkhead Creek Downstream from Elkhead Reservoir near Craig, Colorado

during spring runoff may be varied to make most use of the 

outlet works which is screened to prevent escape of non-native 

gamefish. Operations also may reduce the duration of some 

peak flows downstream. Both of these operational directives are constrained by the need to maintain reservoir pool 

targets to protect wetland mitigation area development in the 

upstream end of the reservoir, and by the sheer volume of 

runoff from Elkhead Creek compared to the volume of the reservoir and capacity of the outlet works. At full use, the outlet 

works can pass about 590 ft3/s and inflows frequently exceed 

1,000 ft3/s for days. During any time of the year, but mostly 

during low flows from July through October, owners of Elkhead Reservoir water may request the release of their water. 

The City of Craig will release the requested flows after notification to the Division Engineer of Colorado Water Division 

#6. After these requested releases, subsequent releases may be 

less than the upstream inflow in order to refill the reservoir.

Methods

Historically, streamflow entering the Yampa River from 

Elkhead Creek was measured at streamflow-gaging station 

09246400 Elkhead Creek below Maynard Gulch near Craig, 

CO (hereinafter called station 09246400). Station 09246400 

was discontinued and a new streamflow-gaging station, 

09246500 Elkhead Creek near Craig, CO (hereinafter called 

station 09246500), was installed (July 2008) upstream from 

the U.S. Highway 40 bridge about 0.81 mi upstream from the 

confluence with the Yampa River. The new gage location is 

downstream from all of the diversions and closer to the confluence with the Yampa River than the previous location, which 

permits better transit estimates to be made over a longer reach 

of Elkhead Creek. Streamflow measurements were determined 

to be plus or minus 5 percent. This is based on most measurement sections having less than 5 percent of the total streamflow and the hydrographer’s assessment of the measurement 

section. 

Description of Measurement Sites

Streamflow was measured at four sites downstream from 

Elkhead Reservoir on Elkhead Creek and at one diversion, 

Norvell ditch (table 1). These sites were selected based on 

having good measurement sections (uniform cross section and 

consistent flow) that were located along the reach from the 

reservoir to the confluence with the Yampa River.

The first site was located immediately downstream 

from the dam in order to verify the releases. Releases from 

the reservoir are set by a SCADA (Supervisory Control and 

Data Acquisition) system, and reported by magnetic flow 

meters, which is considered a very accurate way to monitor 

the reservoir releases (Ray Tenney, Colorado River Water 

Conservation District, oral commun., 2010). The site was 

400 to 500 ft downstream from the dam in a slightly pooled 

area upstream from a riffle and a sandbar in the stream. The 

stream bottom consisted of sand and small cobbles. The flow 

was uniform and fairly even across the cross section, creating 

good measurement conditions. Algal growth was minimal. 

The stream depths ranged from 0.16 to 1.40 ft during times of 

measurements.

The second site was located at the discontinued (period 

of record 1995–2008) streamflow-gaging station, 09246400 

Elkhead Creek below Maynard Gulch near Craig, CO. This 

site was selected because of the long-term streamflow-gaging 

station that had been located there. The stream bottom consisted of sand and small cobbles. The streamflow was uniform 

and fairly even across the cross section, creating good measurement conditions. Algal growth was variable from minimal 

to substantial. Vegetation on the banks grew to the water’s 

edge. The stream depths ranged from 0.24 to 1.72 ft during 

times of measurements. The August 5 measurement was made 

15 ft upstream from the discontinued gage shelter and bridge. 

All other measurements were made 75 ft downstream from 

the discontinued gage shelter and bridge. The bridge structure 

is a control at very high flows. At medium and low flows, the 

control is a cobble and gravel riffle about 20 ft downstream 

from the bridge.

The only active diversion during the study was the 

Norvell ditch located about 0.95 mi upstream from the 

streamflow-gaging station 09246500. There is a Parshall flume 

in the Norvell ditch about 100 ft downstream from the headgate on Elkhead Creek. The streamflow measurements for this 

study were made in the flume. The flume is metal with vertical 

walls, and there was some algae growth. The amount of water 

diverted from the creek was directly related to the stream 

depth and the resultant depth in the ditch. The depths in the 

flume ranged from 0.16 to 0.26 ft during the study. Vegetation 

grew along the ditchbank down to the water’s edge. Diversion 

to Norvell ditch was discontinued for the season on October 3, 

2009.

The third in-stream measurement site was located at 

streamflow-gaging station 09246500 Elkhead Creek near 

Craig, CO (period of record 2008–present). The gage is 

located 25 ft upstream from the U.S. Highway 40 bridge on 

the west side. The stream bottom consisted of sand and small 

cobbles. Vegetation on the banks grew to the water’s edge and 

sometimes into the water. There are stream meanders immediately upstream from the site. The stream depths ranged from 

0.18 to 1.80 ft during times of measurements. The bottom 

conditions were variable and inconsistent, making it difficult 

to get accurate depth measurements and creating only fair 

measurement conditions. Algal growth varied from minimal to 

substantial. The higher releases helped flush the algal growth. 

The bridge structure is a control, and the measurements were 

made 200 ft upstream from the gage and 225 ft upstream from 

the bridge. Due to the variability within the sections, measurement conditions were considered “fair.” 

The fourth measurement site was located 50 to 75 ft 

upstream from the confluence with the Yampa River. The 

stream channel consisted of sand and small cobbles. Sandbars 
Methods 5

were located on both streambanks where Elkhead Creek 

flowed into the Yampa River with a much larger sandbar on 

the upstream Yampa side. The Elkhead velocities were higher 

at the confluence than they were farther upstream, and the 

stream had riffles forming a natural control right at the confluence. Flow was uniform and algae growth was minimal, creating good measurement conditions. The stream depths ranged 

from 0.08 to 1.40 ft during times of measurements.

Streamflow Data

Instantaneous measurements of streamflow were made 

at each of the five measurement sites each time there was a 

change in release from Elkhead Reservoir. Measurements 

were made at least 24 hours after a change in reservoir release 

(streamflow) during steady-state conditions. Instantaneous 

measurements were made 8 times during the study period. 

An additional set of measurements also was made during 

November after reservoir releases had returned to a constant 

5 ft3/s and when the Norvell ditch had not been diverting water 

for about a month. Comparisons were made between all of the 

instantaneous streamflow measurements.

Streamflow was measured using a Flowtracker, an 

Acoustic Doppler Velocimeter (ADV) (http://www.sontek.com/

flowtracker.php; Simpson, 2001; and U.S. Geological Survey 

Office of Surface Water, 2004). ADVs can be used to measure 

streamflow with similar or greater accuracy, efficiency, and 

resolution than conventional mechanical current meter measurements (Oberg and Mueller, 2007). ADVs also can measure 

extreme low flow (for example, velocities as low as 0.003 ft/s 

can be accurately measured) that would be difficult to measure 

using conventional methods (Gotvald and Oberg, 2009). 

Comparisons were made between the volume of water 

released from Elkhead Reservoir (using the SCADA data) and 

the volume of water that flowed past station 09246500 plus the 

volume of water that was diverted to Norvell ditch. By comparing the volume of water released from the reservoir and 

the volume of water at station 09246500 and Norvell ditch, it 

could be determined if Elkhead Creek was gaining or losing 

between the reservoir and station 09246500, and the volume 

could be quantified. The records were compiled on an hourly 

basis for use in the analysis.

Each time there was a change in release at the reservoir, 

the traveltime for the change in streamflow to reach and be 

stable at station 09246500 was calculated. The leading edge 

was noted by the first hourly change in streamflow at station 

09246500, and stable streamflow was noted by consistent 

streamflow at station 09246500 that was equivalent to the 

upstream streamflow.

Elkhead Reservoir Releases

Release records for Elkhead Reservoir were obtained 

from CRWCD (Don Meyer, written commun., 2009). The onthe-hour discharge rate was provided in cubic feet per second 

with the volume of released water in acre-feet. Data were not 

available in shorter time increments, so these data determined 

the time step used in the analysis. For this report, measurement 

error for reservoir releases was considered to be the same as 

for streamflow gaging measurements.

Streamflow-Gaging Station 09246500

The record at station 09246500 (Elkhead Creek near 

Craig, CO) usually is recorded on a 15-minute interval. 

Because the reservoir release records were on a one-hour 

interval, the record was compiled using the usual 15-minute 

interval following the procedures described by Rantz and 

others (1982 a, b). The 15-minute data were then averaged to 

hourly data for comparison to reservoir release data. Fifteenminute interval data were averaged instead of using the 

on-the-hour values, because it would account for streamflow 

variation during that hour. This was especially important when 

the reservoir releases were changing.

Table 1. Location of streamflow measurement sites downstream from Elkhead Reservoir near Craig, Colorado.

[09246400 Elkhead Creek below Maynard Gulch near Craig, CO (discontinued); 09246500 Elkhead Creek near Craig, CO]

Site 

number

Measurement 

site1

Latitude (degrees, 

minutes, seconds)

Longitude (degrees, 

minutes, seconds)

Distance upstream from 

confluence with Yampa 

River (miles)

1 Immediately downstream from dam 40°33'26.01" N. 107°23'11.62" W. 9.65

2 Old gage 09246400 40°32'40.68" N. 107°23'52.95" W. 6.08

3 Norvell ditch 40°32'11.00" N. 107°25'47.00" W. 1.76

4 New gage 09246500 40°31'51.77" N. 107°26'10.11" W. 0.81

5 Confluence with Yampa River 40°31'18.41" N. 107°26'13.40" W. 0.01

1

Measurement site locations are North American datum 1983.
6 Streamflow Gain-Loss Characteristics of Elkhead Creek Downstream from Elkhead Reservoir near Craig, Colorado

Norvell Ditch

The Colorado Department of Water Resources (CODWR) 

collected gage-height data on Norvell ditch. Periodically, when 

the ditch was diverting streamflow, a CODWR employee 

measured the gage height on the Norvell ditch flume and 

used the standard Parshall flume rating table to compute the 

streamflow. The gage height and streamflow were measured 

each time the USGS measured the Elkhead streamflow after a 

change in release from the dam. The Norvell ditch was diverting water from Elkhead Creek during the entire study period, 

and the diversion stopped for the season on October 3, 2009.

Gage height and streamflow were estimated for the time 

between measurements. The gage height in the ditch is controlled by the diversion headgate and also is partially related 

to the stream stage of Elkhead Creek. The greater the stream 

depth and streamflow in Elkhead Creek, the more water that 

is available for diversion. Generally, estimated gage heights 

in the ditch were constant until there was a change in streamflow in the creek. As the streamflow and stage increased, the 

estimated gage heights were increased to parallel the change. 

Sometimes the observed gage height and streamflow in the 

ditch changed even though the creek stage was constant. When 

this occurred, the change in the diversion gage height was prorated over time. This was the best estimate available because 

there was no continuous record of diversion gage height.

Streamflow Characteristics of Elkhead 

Creek

Instantaneous streamflow measurements were compared 

for the different streamflow releases from Elkhead Reservoir. 

Additionally, volumes of water released from the reservoir 

were compared to the combined volumes of water at station 

(09246500 Elkhead Creek near Craig, CO), and the Norvell 

ditch.

Instantaneous Measurement Analysis

Eight instantaneous measurement sets were made from 

August 5 to October 1, 2009, and are presented in table 2 and 

figures 2 and 3. (The additional measurement set made on 

November 5, 2009, was not included in the analysis because 

it was after the flow-augmentation period.) The data are 

presented in two separate figures because of the wide range 

in streamflows from about 5 ft3/s to almost 100 ft3/s. Figure 2 

shows the measurement sets when the streamflow was less 

than 10 ft3/s, and figure 3 shows the measurement sets when 

the streamflows were between 40 and 100 ft3/s. The measured 

streamflow downstream from the dam is usually smaller than 

the combined measured streamflows of station 09246500 

plus Norvell ditch, and the metered flow from the reservoir is 

always smaller than the combined measured streamflows of 

station 09246500 plus Norvell ditch. The measurement error 

of the combined measured streamflows of station 09246500 

plus Norvell ditch are within the measurement error of the 

instantaneous measurement immediately downstream from the 

dam except for October 1 and November 5. Figures 2 and 3 

show the overlap of the plus or minus 5-percent measurement 

error between the sites. The measured streamflow immediately 

downstream from the dam is less than that at station 09246500 

gage plus Norvell ditch except for August 13, August 24, 

and September 3. For August 13 and the September 3, 8, 14, 

and 21 measurements, the combined streamflow at station 

09246500 gage plus Norvell ditch was within the measurement error of the measured instantaneous streamflow at the 

dam. On August 24, the combined streamflow at station 

09246500 plus Norvell ditch was about 1 ft3/s less than the 

measurement error of the measured instantaneous streamflow 

at the dam. On August 5, October 1, and November 5, the 

combined streamflow at station 09246500 plus Norvell ditch 

was greater than the measured streamflow at the dam.

The instantaneous streamflow measurements immediately 

downstream from the dam and the metered flow from the reservoir are within measurement error of each other. For most of 

the measurements, the USGS measurement was slightly higher 

than the metered flow. The predominance of greater streamflows downstream likely is due to the difference between the 

USGS instantaneous measurements and record computation 

with the Supervisory Control and Data Acquisition (SCADA) 

record at the dam. Neither value can be considered more 

accurate than the other; therefore, no adjustments were made 

to the data.

It was determined that the more nearly accurate measurement of Elkhead Creek streamflow into the Yampa was the 

combined streamflow of the station 09246500 gage plus Norvell Ditch as opposed to the combined measured streamflow 

of Norvell ditch plus the confluence. This is likely because 

once Elkhead Creek flows into the most downstream section 

below station 09246500, the creek is flowing in the alluvial 

plain of the Yampa River, and it is difficult to determine 

whether water flowing in this section of Elkhead Creek originated upstream as “Elkhead” water or from the Yampa River 

contributions to the alluvium. Comparisons are still presented 

for data collected at the confluence, but a better estimate of 

Elkhead Creek streamflow is at the streamflow-gaging station 

09246500. 

An additional measurement set was made on November 

5, 2009. Streamflows were still low, but November is outside 

of the time period when UCREFRP would be requesting flowaugmentation releases to the river. Generally, the instantaneous measured streamflow is less downstream from the dam 

than at station 09246500. The data (table 2) show consistent 

increase in streamflow in a downstream direction. The increase 

is small but greater than the 5-percent measurement error. 

This increase is different than that observed earlier in the year 

during low streamflow when there were some slight decreases 

also. This may be due to the contribution from long-term bank 

storage and no evapotranspiration in November compared to 

the summer months.
Streamflow Characteristics of Elkhead Creek 7

Table 2. Instantaneous streamflow measurements, August 5–November 5, 2009.

[09246400 Elkhead Creek below Maynard Gulch near Craig, CO (discontinued); 09246500 Elkhead Creek near Craig, CO; ft3/s, cubic feet per 

second; locations shown in figure 1]

Date

Metered 

flow from 

reservoir

(ft3/s)

Immediately 

downstream 

from dam

(ft3/s)

09246400

(ft3/s)

Norvell 

ditch

(ft3/s)

09246500

(ft3/s)

09246500 

plus Norvell 

ditch

(ft3/s)

Confluence 

with Yampa 

River

(ft3/s)

Confluence plus 

Norvell ditch

(ft3/s)

08/05/2009 5.00 4.67 4.69 0.676 4.72 5.40 4.45 5.13

08/13/2009 49.5 53.2 50.9 0.596 50.3 50.9 50.5 51.1

08/24/2009 84.3 92.9 88.2 1.62 85.6 87.2 87.9 89.5

09/03/2009 50.3 54.0 51.8 0.921 51.6 52.5 52 52.9

09/08/2009 49.2 52.1 52.8 0.911 52.2 53.1 51.2 52.1

09/14/2009 59.6 62.6 64.5 1.27 63.5 64.8 61.5 62.8

09/21/2009 45.2 47.0 48.1 1.24 47.5 48.7 44.7 45.9

10/01/2009 4.97 4.82 6.36 1.08 6.26 7.34 6.52 7.60

11/05/2009 4.97 4.99 5.23 0.00 5.58 5.58 5.64 5.64

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

9.0

07/26/09 08/15/09 09/04/09 09/24/09 10/14/09 11/03/09 11/23/09

Streamflo

w, in cubic feet per second

Date

Immediately downstream from dam

Station 09246500 plus Norvell ditch

Confluence plus Norvell ditch

Plus or minus 5-percent measurement error bars,

 colored to match color of measurement location

Streamflow conditions not steady state on 10/01/2009

EXPLANATION

Figure 2. Instantaneous streamflow measurements at selected sites, August 5, October 3, and November 5, 2009.
8 Streamflow Gain-Loss Characteristics of Elkhead Creek Downstream from Elkhead Reservoir near Craig, Colorado

Water Volume Comparisons 

One way of determining whether a stream reach is 

gaining or losing is to compare volumes of water moving 

past specific locations within the reach for a specified time 

period. For this study, comparisons were made between the 

volume of water released from Elkhead Reservoir as determined by the hourly SCADA-system data and the volume 

of water that flowed past station 09246500 (Elkhead near 

Craig, CO) as determined by the hourly averaged station data 

plus the estimated volume of water that was diverted to the 

Norvell ditch. Time periods for volume comparison were 

determined for periods when there was a change in release 

from the reservoir, allowing for stabilization of streamflows 

downstream. The volume of water accounted for downstream 

generally was larger than the volume of flow released from 

the reservoir as recorded by the SCADA system on the dam 

and may be an artifact of the SCADA-system metered flow 

being slightly less than most of the instantaneous measurements immediately downstream from the dam and at station 09246500. The difference between the SCADA-system 

metered flow and the instantaneous measured streamflow may 

be due to groundwater contribution to the creek between the 

dam and measurement section. For all time periods except for 

August 19 to September 2, the volume of water was greater 

downstream than upstream (table 3). During this time period, 

the relative percent difference between the volume of water 

released from Elkhead Reservoir as determined from the reservoir hourly release data and the volume of water that flowed 

past station 09246500 (Elkhead near Craig, CO) plus the 

volume of water that was diverted to Norvell ditch typically 

was less than or near 5 percent (table 3) except for August 19 

(fig. 4). An increase in reservoir release occurred on August 19 

(table 4). It took 10 hours for the full increase in streamflow to 

reach the downstream measurement site.

Given the 5-percent measurement error, the data indicate 

that, overall, the stream reach from Elkhead Reservoir to station 09246500 and ultimately to the Yampa River from August 

10, 2009, through October 4, 2009, is neither gaining nor 

losing. The percent differences for calculated volumes were 

generally less than 5 percent except when the release rate from 

the reservoir was changing. Streamflow that was accounted 

for upstream at the site downstream from the dam was not yet 

Streamflo

w, in cubic feet per second

08/10/09 08/15/09 08/20/09 08/25/09 08/30/09 09/04/09 09/09/09 09/14/09 09/19/09

40

70

80

90

100

Date

Immediately downstream from dam

Station 09246500 plus Norvell ditch

Confluence plus Norvell ditch

Plus or minus 5-percent measurement error bars,

 colored to match color of measurement location

09/24/09

50

60

EXPLANATION

Figure 3. Instantaneous streamflow measurements at selected sites, August–September 2009.
Streamflow Characteristics of Elkhead Creek 9

Table 3. Volume of water released from Elkhead Reservoir, August 1 to October 4, 2009.

[ft3/s, cubic feet per second]

Date Time

Total volume of 

water released 

from reservoir, 

in acre-feet1

Total volume of 

water at station 

09246500 plus 

Norvell ditch, in 

acre-feet2

Upstream 

volume minus 

downstream 

volume, in 

acre-feet

Reservoir 

releases

Percent 

difference3 Reach conditions

08/01/2009

08/10/2009

0:00:00

11:00:00 93.94 99.82

–5.88

prior to any 

release 

changes

6.07

more streamflow 

downstream

08/10/2009

08/19/2009

12:00:00

3:00:00 833.32 844.24

–10.92

increased 

from 

about 5 

to 50 ft3/s 1.30

more streamflow 

downstream

08/19/2009

09/02/2009

4:00:00

12:00:00 2,378.54 2,295.91

82.63

increased 

from 

about 50 

to 85 ft3/s 3.54

less streamflow 

upstream

09/02/2009

09/10/2009

13:00:00

5:00:00 775.02 817.22

–42.20

decreased 

from 

about 85 

to 50 ft3/s 5.30

more streamflow 

downstream

09/10/2009

09/16/2009

6:00:00

7:00:00 715.43 728.77

–13.34

increased 

from 

about 50 

to 60 ft3/s 1.85

more streamflow 

downstream

09/16/2009

09/30/2009

8:00:00

13:00:00 1,253.78 1,323.11

–69.33

decreased 

from 

about 60 

to 45 ft3/s 5.38

more streamflow 

downstream

09/30/2009

10/02/2009

14:00:00

18:00:00 21.68 59.86

–38.18

decreased 

from 

about 45 

to 5 ft3/s 93.65

more streamflow 

downstream

10/02/2009

10/04/2009

19:00:00

23:00:00 21.72 22.95

–1.23

decreased 

to about 

5 ft3/s 5.51

more streamflow 

downstream

more streamflow 

Total 6,093.43 6,191.88 –98.45 1.60 downstream

1

Determined using the hourly Supervisory Control and Data Acquisition system data.

2

Determined using the averaged hourly station data.

3

Percent difference = |(Total volume of water released from reservoir–Total volume of water at station 09246500 plus Norvell Ditch)/((Total 

 volume of water released from reservoir+Total volume of water at station 09246500 plus Norvell Ditch)/2)|×100.
10 Streamflow Gain-Loss Characteristics of Elkhead Creek Downstream from Elkhead Reservoir near Craig, Colorado

Streamflow released from reservoir from Supervisory Control

 and Data Acquisition record

Streamflow at station 09246500

Combined streamflow of station 09246500 plus Norvell ditch

Instantaneous measurement made immediately downstream from dam

Instantaneous measurement made at station 09246500

Instantaneous measurement made at confluence with the Yampa River

Instantaneous measurement made at Norvell ditch

0

10

20

30

40

50

60

70

80

90

100

Streamflow, in cubic feet per second

Date and time

08/1/2009 08/8/2009 08/15/2009 08/22/2009 08/29/2009 09/5/2009 09/12/2009 09/19/2009 09/26/2009 10/3/2009

EXPLANATION

Figure 4. Instantaneous and continuous record of streamflow downstream from Elkhead Reservoir, August 1 to October 4, 2009.

accounted for downstream at station 09246500 because of the 

traveltime between the two sites. 

Traveltime

Traveltimes between the reservoir and station 09246500 

were estimated using the hourly release data from the dam and 

hourly unit values at the streamflow-gaging station. Hourly 

data were used because the most frequently recorded available 

information from the dam was hourly, and it was decided to 

use the same time step at the gaging station. Table 4 shows the 

various traveltimes when there was a change in flow release 

at the dam. The time when the leading edge of the streamflow 

change arrived was determined by the time the initial change 

in streamflow occurred downstream. Streamflow was determined to be stable when the streamflow at station 09246500 

was similar to the streamflow released from the reservoir. 

Traveltime ranged from 7 hours at the mid-flow increasing streamflows up to 23 hours for the low-flow decreasing 

streamflows. The instantaneous measurements generally 

were rated “fair,” plus or minus 8 percent or “good,” plus or 

minus 5 percent (Rantz and others, 1982b). The streamflow 

record was rated “good” (U.S. Geological Survey, 2010a). 

Traveltimes are shorter at higher streamflows than at lower 

streamflows because of higher stream velocities. When there 

is an abrupt increase in streamflow, such as an increase in 

release from the reservoir, initially there is a more distinct 

front to the water traveling downstream. The frontal wave of 

water disperses longitudinally in the stream channel so that the 

increase in streamflow becomes more gradual downstream as 

it moves farther downstream. When there is an abrupt decrease 

in streamflow, such as when there is a decrease in release from 

the reservoir, the longitudinal dispersion occurs over a longer 

period of time. Table 4 shows that the traveltime from the 

streamflow on August 10 increases from about 4.91 ft3/s at the 

dam to about 50 ft3/s at station 09246500, with the streamflow 

stabilizing in about 11 hours. When streamflow decreased on 

September 30 from about 45 ft3/s at the dam to about 6 ft3/s at 

station 09246500, the streamflow stabilized in about 23 hours.

Summary

From August through early October 2009, the USGS, 

in cooperation with the Colorado Water Conservation Board, 

the Upper Colorado River Endangered Fish Recovery Program, the Colorado Division of Water Resources, and City of 

Craig, studied the gain-loss characteristics of Elkhead Creek 

downstream from Elkhead Reservoir to its confluence with the 

Yampa River. Earlier qualitative interpretation of streamflow 
Summary 11

Table 4. Traveltime after a change in flow release from just downstream from the dam to station 09246500 Elkhead 

Creek near Craig, CO, August–September 2009.

[SCADA, Supervisory Control and Data Acquisition; ft3/s, cubic feet per second]

Date Time

SCADA 

measured 

streamflow 

at the dam

(ft3/s)

Date Time

Streamflow 

at station 

09246500

(ft3/s)

Description 

of streamflow change 

at station 

09246500

Traveltime

(hours)

08/10/2009 16:00:00 4.91

08/10/2009 17:00:00 49.72

08/11/2009 0:00:00 4.30 8

08/11/2009 1:00:00 10.13 Leading edge 9

08/11/2009 2:00:00 42.50 10

08/11/2009 3:00:00 49.75 Stable 11

08/11/2009 4:00:00 51.00 12

08/11/2009 5:00:00 51.00 13

08/11/2009 6:00:00 51.00 14

08/19/2009 8:00:00 51.08

08/19/2009 9:00:00 84.99

08/19/2009 14:00:00 54.25 5

08/19/2009 15:00:00 64.75 Leading edge 6

08/19/2009 16:00:00 63.25 7

08/19/2009 17:00:00 57.50 8

08/19/2009 18:00:00 70.25 9

08/19/2009 19:00:00 79.50 Stable 10

08/19/2009 20:00:00 80.00 11

08/19/2009 21:00:00 80.00 12

08/19/2009 22:00:00 80.00 13

09/02/2009 17:00:00 83.74

09/02/2009 18:00:00 49.98

09/02/2009 22:00:00 78.50

09/02/2009 23:00:00 69.50 Leading edge 5

09/03/2009 0:00:00 58.50 6

09/03/2009 1:00:00 53.50 7

09/03/2009 2:00:00 52.25 Stable 8

09/03/2009 3:00:00 52.00 9

09/03/2009 4:00:00 52.00 10

09/03/2009 5:00:00 51.75 11

09/10/2009 10:00:00 49.69

09/10/2009 11:00:00 59.9

09/10/2009 15:00:00 52.00

09/10/2009 16:00:00 53.50 Leading edge 5

09/10/2009 17:00:00 57.50 6

09/10/2009 18:00:00 60.00 Stable 7

09/10/2009 19:00:00 60.00 8
12 Streamflow Gain-Loss Characteristics of Elkhead Creek Downstream from Elkhead Reservoir near Craig, Colorado

Table 4. Traveltime after a change in flow release from just downstream from the dam to station 09246500 Elkhead 

Creek near Craig, CO, August–September 2009.—Continued

[SCADA, Supervisory Control and Data Acquisition; ft3/s, cubic feet per second]

Date Time

SCADA 

measured 

streamflow 

at the dam

(ft3/s)

Date Time

Streamflow 

at station 

09246500

(ft3/s)

Description 

of streamflow change 

at station 

09246500

Traveltime

(hours)

09/10/2009 20:00:00 60.00 9

09/16/2009 13:00:00 59.45

09/16/2009 14:00:00 45.47

09/16/2009 17:00:00 59.50 3

09/16/2009 18:00:00 57.75 Leading edge 4

09/16/2009 19:00:00 55.00 5

09/16/2009 20:00:00 50.25 6

09/16/2009 21:00:00 48.00 7

09/16/2009 22:00:00 47.00 Stable 8

09/16/2009 23:00:00 47.25 9

09/17/2009 0:00:00 47.00 10

09/30/2009 13:00:00 44.94

09/30/2009 14:00:00 4.91

09/30/2009 18:00:00 46.25

09/30/2009 19:00:00 43.25 Leading edge 5

09/30/2009 20:00:00 37.25 6

09/30/2009 21:00:00 29.75 7

09/30/2009 22:00:00 23.25 8

09/30/2009 23:00:00 18.50 9

10/01/2009 0:00:00 15.25 10

10/01/2009 1:00:00 13.00 11

10/01/2009 2:00:00 10.75 12

10/01/2009 3:00:00 9.68 12

10/01/2009 4:00:00 8.70 14

10/01/2009 5:00:00 8.13 15

10/01/2009 6:00:00 7.60 16

10/01/2009 7:00:00 7.50 17

10/01/2009 8:00:00 7.30 18

10/01/2009 9:00:00 7.20 19

10/01/2009 10:00:00 7.20 20

10/01/2009 11:00:00 7.00 21

10/01/2009 12:00:00 6.60 22

10/01/2009 13:00:00 6.00 Stable 23

10/01/2009 14:00:00 6.00 24

10/01/2009 15:00:00 6.00 25
References Cited 13

data downstream from the reservoir indicated that there could 

be a transit loss of nearly 10 percent. This potential loss could 

be a significant portion of the releases from Elkhead Reservoir 

requested by Upper Colorado River Endangered Fish Recovery Program during late summer and early fall for improving 

critical habitat for endangered fish downstream in the Yampa 

River. Information on the gain-loss characteristics was needed 

for effective management of the reservoir releases requested 

by Upper Colorado River Endangered Fish Recovery Program 

during late summer and early fall for improving critical habitat 

for endangered fish downstream in the Yampa River. Eight 

sets of streamflow measurements were made at four strategic instream sites and at one diversion downstream from the 

reservoir. An additional measurement set was made after the 

study period during low-flow conditions in November 2009. 

Streamflow measurements were made using an Acoustic Doppler Velocimeter to provide high accuracy and consistency, 

especially at low flows. During this study, streamflow ranged 

from about 5 ft3

/s to almost 100 ft3/s with step increments in 

between. Measurements were made at least 24 hours after a 

change in reservoir release (streamflow) during steady-state 

conditions.

The instantaneous streamflow measurements and the 

streamflow volume comparisons show the reach of Elkhead 

Creek immediately downstream from Elkhead Reservoir to 

the streamflow-gaging station 09246500 Elkhead Creek near 

Craig, CO, is neither a gaining nor losing reach. The instantaneous measurements immediately downstream from the dam 

and the combined measurements of Norvell ditch plus station 

09246500 generally are within the 5 percent measurement 

error of each other. The variability of data is such that sometimes the streamflow is greater upstream and sometimes the 

streamflow is greater downstream, concluding in a net gainloss volume of near zero. Streamflow volumes were calculated 

for multiple time periods, as determined by a change in release 

from the reservoir. Streamflow volumes were greater downstream than upstream for all but one time period. Groundwater may be contributing to the creek between the dam 

and measurement sections causing the USGS instantaneous 

measurements and record computation to be slightly larger 

than the Supervisory Control and Data Acquisition record at 

the dam. Immediately following an increase in streamflow, the 

downstream volume was smaller, but this was an artifact of 

the traveltime between the two sites. Traveltimes varied from 

7 to 23 hours and were shorter at higher streamflows, when 

streamflow was increasing, than at lower streamflows when 

the streamflow was decreasing. 

Acknowledgments

The author gratefully acknowledges the contributions of 

USGS employees, cooperators, and landowners, which made 

this study possible. Fieldwork was done by Kevin Murphy and 

Kyle Davis (USGS). Field assistance/consultation was provided by Kathy Bower (COWDR) and John Elliott (USGS). 

Elkhead Reservoir operation information was provided by Ray 

Tenney and Don Meyers (CRWCD). Landowner Raymond 

Earle provided access to the Elkhead Creek confluence with 

the Yampa River, and landowner Winfield Pankey provided 

access to Norvell ditch. Technical reviews of the report were 

provided by David Brown and Kenneth Odom (USGS).

References Cited

Colorado River Water Conservation District, 2010, Elkhead 

Reservoir Enlargement, accessed February 26, 2010, 

http://www.crwcd.org/media/uploads/Elkhead_fact_

sheet_9_06.pdf. 

DiLuzio, Mario, 2007, Seamless daily precipitation for the 

conterminous United States, 1960–2001: Data available 

from the U.S. Department of Agriculture Geospatial Data 

Gateway, accessed June 11, 2008, http://datagateway.nrcs.

usda.gov/NextPage.aspx.

Elliott, J.G., and Gyetvai, Stevan, 1999, Channel-pattern 

adjustments and geomorphic characteristics of Elkhead 

Creek, Colorado, 1937-97: U.S. Geological Survey 

Water-Resources Investigations Report 99–4098, 39 p.

Gotvald, A.J., and Oberg, K.A., 2009, Acoustic Doppler 

profiler applications used in rivers and estuaries by the 

U.S. Geological Survey: U.S. Geological Survey Fact sheet 

2008–3096, 4 p.

Kuhn, Gerhard, Stevens, M.R., and Elliott, J.G., 2003, 

Hydrology and water quality of Elkhead Creek and Elkhead 

Reservoir near Craig, Colorado, July 1995–September 

2001: U.S. Geological Survey Water-Resources Investigations Report 2003–4220, 71 p.

Oberg, K.A., and Mueller, D.S., 2007, Validation of streamflow measurements made with Acoustic Doppler Current 

Profilers: Journal of Hydraulic Engineering, v. 133, no. 12, 

p. 1421–1432. 

Rantz, S.E., and others, 1982a, Measurement and computation of streamflow—Volume 1. Measurement of stage and 

discharge: U.S. Geological Survey Water-Supply Paper 

2175, 313 p.

Rantz, S.E., and others, 1982b, Measurement and computation 

of streamflow—Volume 2. Computation of discharge: U.S. 

Geological Survey Water-Supply Paper 2175, 373 p.

Simpson, M.R., 2001, Discharge measurements using a broadband acoustic Doppler current profiler: U.S. Geological 

Survey Open-File Report 2001–01, 123 p.

Tweto, Ogden, 1976, Geologic map of the Craig 1°×2° quadrangle, northwestern Colorado: U.S. Geological Survey 

Miscellaneous Investigations Series Map I–972.
14 Streamflow Gain-Loss Characteristics of Elkhead Creek Downstream from Elkhead Reservoir near Craig, Colorado

U.S. Geological Survey, 2010a, Records management system, 

station analysis for station 09246500, accessed March 22, 

2010, http://tx.cr.usgs.gov/field/sqlsims/start.asp?office_

id=8&district_cd=08 .

U.S. Geological Survey, 2010b, Streamstats—A water 

resources web application, accessed January 27, 2010, 

http://streamstatsags.cr.usgs.gov/co_ss/default.aspx?stabbr

=co&dt=1264627864639.

U.S. Geological Survey Office of Surface Water, 2004, Policy 

on the use of the FlowTracker for discharge measurements: 

Office of Surface Water Technical Memo 2004.04, 9 p., 

http://hydroacoustics.usgs.gov/memos/OSW2004-04.pdf .

Publishing support provided by: 

Denver Publishing Service Center

For more information concerning this publication, contact:

Director, USGS Colorado Water Science Center

Box 25046, Mail Stop 415

Denver, CO 80225

(303) 236-4882

Or visit the Colorado Water Science Center Web site at:

http://co.water.usgs.gov/