Prepared in cooperation with the Virginia Department of Environmental Quality

Rating Stability, and Frequency and Magnitude of Shifts,

for Streamgages in Virginia Through Water Year 2013

Scientific Investigations Report 2017–5137

U.S. Department of the Interior

U.S. Geological Survey

Rating Stability, and Frequency and 

Magnitude of Shifts, for Streamgages 

in Virginia Through Water Year 2013

By Terence Messinger and Robert W. Burgholzer

Prepared in cooperation with the Virginia Department of Environmental Quality

Scientific Investigations Report 2017–5137

U.S. Department of the Interior

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

RYAN K. ZINKE, Secretary

U.S. Geological Survey

James F. Reilly II, Director

U.S. Geological Survey, Reston, Virginia: 2018

For more information on the USGS—the Federal source for science about the Earth, its natural and living 

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visit https://store.usgs.gov.

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U.S. Government.

Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials 

as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

Suggested citation:

Messinger, T., and Burgholzer, R.W., 2018, Rating stability, and frequency and magnitude of shifts, for streamgages 

in Virginia through water year 2013: U.S. Geological Survey Scientific Investigations Report 2017–5137, 91 p., https://

doi.org/10.3133/sir20175137. 

ISSN 2328-0328 (online)
iii

Acknowledgments

Many individuals contributed to the successful development of this study and report. Danny 

Daniels of the U.S. Geological Survey (USGS) entered flow measurements into the database 

over a period exceeding 10 years, which made the analysis possible. Thomas Gibson of the Virginia Department of Environmental Quality and Dennis Adams, Jim Duda, Karl Dydak, Mike Eckenwiler, Amanda Groves, Donna Justus, Keith Lambert, Russ Lotspeich, and Carlos Rodriguez, 

all of USGS, participated in interviews regarding the history, and bed and control characteristics, 

of streamgages. Discussions with Julie Kiang, Robert Mason, and John Atkins, all of USGS, 

were helpful in developing the analytical approach for this project. This report was improved by 

technical reviews by Russ Lotspeich and Robert Mason.
iv

Contents

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

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

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

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

Description of the Virginia Streamgage Network ...........................................................................2

Streamgaging Operations.............................................................................................................................2

General Field and Office Procedures ................................................................................................2

Flow Data Computation........................................................................................................................8

Ratings and Shifts for Streamgages in Virginia through 2013..............................................................10

Patterns in the Stability of Stage-Flow Relations...................................................................................16

Development of Long-Term Average Ratings ................................................................................16

Comparison of Smoothing Curves...........................................................................................16

Classification of Rating Families .............................................................................................18

Seasonal Changes to Stage-Flow Relations ..................................................................................22

Long-Term Changes to Stage-Flow Relations................................................................................22

Estimated Provisional Flows (AltFlows) ...................................................................................................23

AltFlow Development .........................................................................................................................25

Rating Availability, Acquisition, and Compilation .................................................................25

Special Conditions Affecting Some AltFlows........................................................................26

Streamgage Datum Changes..........................................................................................26

Moving a Streamgage......................................................................................................26

Suspension of Streamgage Operations ........................................................................27

Estimated and Qualified Daily Flows .............................................................................27

Days of Zero Flow .............................................................................................................29

Previously Undefined Ratings.........................................................................................30

Unusual Sites.....................................................................................................................34

Comparison of Ratings and Measurements as a Check on Rating Compilation.............34

Examples of AltFlow Hydrographs...................................................................................................35

Stability Metrics and Their Relations to Each Other and to Basin Characteristics..........................35

Description of Stability Metrics........................................................................................................35

Stability Class .............................................................................................................................35

Metrics Derived from AltFlows................................................................................................37

Other Metrics..............................................................................................................................39

Relations Among Stability Metrics ..................................................................................................40

Stability Metrics and their Relations to Site and Basin Characteristics ...................................44

Caveats, Limitations, and Suggestions for Further Study .....................................................................44

Summary........................................................................................................................................................46

References Cited..........................................................................................................................................47

Appendix 1. Plots for real-time streamgages in Virginia ...................................................................87

Appendix 2. Computation of Alternative Flow Data............................................................................88

Appendix 3. UNIX shell scripts used to develop AltFlow record......................................................90

Appendix 4. Plots showing daily time series of Qsame and Qprev .........................................................91
v

Plates

1. A, Long-term stage-flow relations at selected streamgages in Virginia with

a generalized additive model smoother, B, seasonal variation of relations

between residual of flow and date with a LOESS smoother, and C, seasonal

variation of relations between residual of flow and Julian date

with a LOESS smoother .................................................................................... available online

2. Patterns of variation in, A, long-term stage-flow relations at selected streamgages

in Virginia, B, residual of flow and date with a LOESS smoother, and C, residual

of flow and Julian date with a LOESS smoother .......................................... available online

3. AltFlow hydrographs for four selected streamgages in Virginia, water years

1991–2013 ............................................................................................................ available online

4. Matrix of proposed stability metrics developed using daily flow, shifted ratings,

and flow measurements for streamgages in Virginia, water years

1991–2013 ............................................................................................................ available online

5. Scatterplot matrixes of stage-flow relation stability metrics in relation to selected

basin characteristics for A, 64 plots and, B, 88 plots, for streamgages in Virginia,

water years 1991–2013...................................................................................... available online

Figures

1. Maps showing elevation, physiographic provinces, streams, and streamgages

active as of September 30, 2013, in Virginia.............................................................................3

2. Graph showing relation between start dates of shifts and dates of final

modification of shifts at streamgages in Virginia, water years 1991−2013 .......................14

3. Boxplot showing number of days between start and final modification of shifts

at streamgages in Virginia, 1990–2013 ....................................................................................15

4. Graphs showing rating curves for stage-flow relations for streamgage 01634000,

North Fork Shenandoah River at Strasburg, VA, with six smoothers applied:

A, linear regression, B, Gaussian LOESS, C, LOESS, symmetric 0.75, D, LOESS

symmetric 0.5, E, LOESS, symmetric 0.25, and F, generalized additive model ..................17

5. Graphs showing streamgage 01668000, Rappahannock River near Fredericksburg,

VA, showing: A, long-term stage-flow relations with a generalized additive model

smoother, B, residual of flow and date with a LOESS smoother, and C, residual

of flow and Julian date with a LOESS smoother ...................................................................19

6. Boxplots showing distribution of variability metrics for stage-flow relations,

by descriptive stability class, for streamgages in Virginia active

on September 30, 2013 ...............................................................................................................22

7. Flowchart of major actions and data sources for computing alternative flow

tables for Virginia streams, water years 1991–2013 .............................................................24

8. Boxplots showing distribution of proposed stage-flow relation stability and

real-time flow reliability metrics by descriptive stability class for streamgages

in Virginia active on September 30, 2013 ................................................................................43
vi

Tables

1. Virginia streamgage numbers, names, drainage areas, locations, and elevations ..........4

2. Earliest dates for base ratings and shifts in the Virginia node of the National Water

Information System database for streamgages active as of September 30, 2013...........49

3. Number of unique shifts recorded in the National Water Information System

at streamgages in Virginia active as of September 30, 2013; includes multiple shifts

begun on the same day..............................................................................................................53

4. Number of base ratings and number of days they were in effect for streamgages

in Virginia, water years 1991–2013, for periods when the ratings were stored

in the National Water Information System.............................................................................58

5. Selected characteristics of daily flows on days that base ratings began

at streamgages in Virginia, water years 1991–2013..............................................................11

6. Selected characteristics of daily flows on days that shifts began at streamgages

in Virginia, water years 1991–2013...........................................................................................12

7. Dates on which shifts began at 30 or more streamgages, and flow characteristics

for that day at the streamgage in question in Virginia, water years 1991–2013...............13

8. Hydrographer descriptions of controls for streamgages in Virginia at which

real-time flow data were collected as of September 30, 2013, and descriptions

of associated features of interest................................................................... available online

9. Rating families, dates they were in effect, variability statistics, and explanations

for their causes for streamgages active in Virginia in October 2013.................................62

10. Locations, magnitudes, and dates of datum changes for streamgages in Virginia,

water years 1990–2013...............................................................................................................26

11. Streamgages that were moved to new gaging pools, and dates of the move,

in Virginia, water years 1991–2013...........................................................................................27

12. Virginia streamgages that were discontinued and reactivated for 30 or more

consecutive days, and the dates they were discontinued and reactivated,

water years 1991–2013...............................................................................................................28

13. Number of days with estimated and qualified flows for streamgages in Virginia,

water years 1991–2013...............................................................................................................69

14. Number of days with zero flow for streamgages in Virginia, water years

1991–2013 .....................................................................................................................................29

15. Number of days when Qsame equaled zero but Qprev did not, and mean

and maximum values of Qprev for those days for streamgages in Virginia,

water years 1991–2013...............................................................................................................30

16. Number of days when Qprev equaled zero but Qsame did not, with mean

and maximum values of Qprev for those days for streamgages in Virginia,

water years 1991–2013...............................................................................................................31

17. Number of times ratings entered ranges that had been undefined in the previous

actual rating and set equal to the defined rating minimum for the purpose

of this analysis, and number of days they were in such ranges for streamgages

in Virginia, water years 1991–2013...........................................................................................32

18. Days of approved flow record less than their respective rating minima for

streamgages in Virginia, water years 1991–2013 ..................................................................33

19. Number of comparisons of directly measured flow to the rating in effect

at the time of measurement relative to divergence thresholds for streamgages

in Virginia, water years 1991–2013...........................................................................................73

20. Summary of selected rating stability metrics for streamgages in Virginia,

water years 1991–2013...................................................................................... available online
vii

21. Number of days of available Qprev record for streamgages in Virginia,

by streamgage and month, and earliest date the records are available,

during water years 1991–2013 ..................................................................................................77

22. Control and rating stability assessments made by senior hydrographers

in the Virginia Water Science Center and Virginia Department of Environmental

Quality for streamgages in Virginia active September 30, 2013..........................................82

23. Instructions to senior hydrographers for answering a control and rating stability

questionnaire, for Virginia streamgages active September 30, 2013.................................36

24. Average of daily percent errors for flow in Virginia streams, by month

and percentile range......................................................................................... available online

25. Root-mean-square error of AltFlows and number of days of record for streamgages

on Virginia streams by month and percentile of monthly flow, water years

1991–2013 ............................................................................................................ available online

26. Proportion of days when the difference between Qprev and Qsame was zero

at streamgages in Virginia, by month, 1990–2013......................................... available online

27. Correlation matrix of Spearman’s rho correlation coefficients for proposed

rating-stability metrics developed from daily flows, shifted ratings, and flow

measurements for streamgages in Virginia, water years 1991–2013 ................................41

28. Correlation matrix of Spearman’s rho correlation coefficients for selected rating

stability metrics and selected basin characteristics for streamgages active

in Virginia, September 30, 2013.................................................................................................45
viii

Conversion Factors

U.S. customary units to International System of Units

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2) 259.0 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2) 

Flow rate

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

Datum

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 

GAM Generalized additive model

NWIS National Water Information System

RMSE Root-mean-square error

USGS U.S. Geological Survey

VDEQ Virginia Department of Environmental Quality
Rating Stability, and Frequency and Magnitude of Shifts, 

for Streamgages in Virginia Through Water Year 2013

Terence Messinger1 and Robert W. Burgholzer2

Abstract

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

Virginia Department of Environmental Quality, has quantified several measures of rating stability and the frequency 

and magnitude of changes to ratings through time for 174 

real-time continuous streamgages active in Virginia as of 

September 30, 2013. Generalized additive models (GAMs) 

were fitted through all available flow measurements for all 

the streamgages in Virginia’s real-time network as of September 30, 2013, with at least 20 flow measurements with positive flow values. For each measurement with a positive flow 

value, residuals from the GAM curve were calculated. Time 

series of these residuals were used to identify major changes 

to the control (the stream feature or features which control 

the relation between stage and flow); the measurements in the 

periods of equilibrium between major changes were assigned 

to rating families. Of the 127 rating families that were 

identified as being distinct at sites, documented explanations 

were found for 67 of them. The most common reasons for 

the control to change enough to warrant a new rating family are moving the streamgage (28 times), floods (26 times), 

and construction activities (13 times). Provisional flow data 

from any streamgage that has recently experienced a major 

flood, regardless of historical stability, are more uncertain 

than usual until post-flood evidence emerges that the rating 

is stable, or if the rating has changed, until it is known to be 

well defined.

A direct comparison between provisional flow data 

(those data originally displayed on the web in near-real time) 

and flow data approved for publication following subsequent 

flow measurements and review could not be made because 

provisional flow data have not been archived. As a substitute, 

alternative flow (AltFlow) tables were constructed for periods 

with complete records of shifts and ratings. Alternate flows 

consist of Qsame, the flow value from the shifted rating table 

used to compute the daily flow value at the time of the most 

1

U.S. Geological Survey

2

Virginia Department of Environmental Quality

recent flow measurement that corresponds to the gage height 

of each day’s daily flow value, and Qprev, the flow value from 

the shifted rating table in effect at the time of the previous 

flow measurement that corresponds to the gage height of each 

day’s daily flow value.

Several metrics that summarize AltFlow tables were 

computed and evaluated; particular importance was given to 

how well the metrics agreed with the descriptive stability class 

developed from interviews with hydrographers. Of these stability metrics, at least four were determined to be meaningful 

and to represent different aspects of control stability that might 

be relevant to water managers: total root mean square error 

between log-transformed Qprev and Qsame, percentage of days 

when the difference between Qprev and Qsame is greater than (>) 

Qsame, the sum of absolute AltFlow error divided by total flow, 

and percentage of days with zero difference between Qprev

and Qsame. 

Three other meaningful metrics of control stability or 

provisional flow-data quality were computed: R2 (coefficient 

of determination) of GAMs from the flow measurements, percentage of total estimated days, and percentage of estimated 

days in the winter. Correlations among metrics varied, indicating they responded to different aspects of control stability. 

Relations among the various stability metrics and quantitative 

basin and site characteristics were weak. Although quantitative 

relations between stability metrics and basin and site characteristics were all weak, some common patterns still emerged. 

Controls and ratings on large streams [>500-square mile (mi2) 

drainage area] and at high elevations (>1,000 feet) were more 

likely to be stable than controls and ratings on small streams 

(less than (<) 100-mi2 drainage area) and at low elevations 

(<500 feet). There were exceptions to both generalizations, 

and streamgages that were intermediate in both characteristics 

varied widely in stability.

Typical timing of record computation changed during 

water years 1991–2013. From 1991 through 2001, the median 

number of days between the start date of the shift and the 

date it was created fluctuated between about 240 and about 

300 days and decreased by about 4 months from 2001 to 2002. 

Only in 2012 and 2013 did one-half of the shifts have a delay 

of about 60 days between start date and final modification. 
2 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

Introduction

The U.S. Geological Survey (USGS) began posting flow 

data on the internet in near real time in 1994, during a time 

when streamgages equipped with satellite telemetry increased 

from 14 percent in 1983 to 64 percent in 1997 (U.S. Geological Survey, 1998). Since then, many emergency responders, 

water managers, anglers, boaters, and others increasingly have 

come to rely on the accuracy of real-time flow data to make 

decisions that affect the safety of life and property. 

Continuous flow typically is not measured directly. 

Instead, it is computed from stage measurements using a “rating curve,” or a curve fitted through points representing the 

direct measurements of stage and flow that are made during 

periodic streamgage inspections. At all streamgages, rating 

curves change through time as a result of changes to “controls,” the bed or channel features that control the water level 

in the gaging pool. The gaging pool is the pool of water where 

stage, or gage height, is measured. The stability of controls 

varies greatly among streamgages. Changes to controls can 

be determined only by inspection or measurement, can be 

quantified only by measurement, and are the reason periodic 

flow measurements are made. Reliability of real-time flow 

data depends primarily on the stability of the control. Other 

factors are also important, however, notably how prone 

the streamgage intake or orifice is to sediment deposition. 

Changes to controls that require several flow measurements to 

define are common. 

The USGS, in cooperation with the Virginia Department 

of Environmental Quality (VDEQ), has quantified several 

measures of rating stability and the frequency and magnitude 

of changes to ratings through time for 174 real-time continuous streamgages active in Virginia as of October 2013. This 

study is intended to help water managers understand how 

much confidence may be placed in preliminary flow data collected at these streamgages.

Purpose and Scope

The purpose of this report is to describe the steps taken to 

quantify the stability of stage-flow ratings for streams in Virginia, to help evaluate the reliability of the ratings to provide 

real-time flow data. Two different analytical approaches are 

employed. (1) Flow measurements are compared to long-term 

average ratings by flow, date, and day-of-year, and (2) mean 

daily flows for water years1 1991–2013 are compared to flows 

that would have been computed from the rating in effect when 

the previous flow measurement was made. Stability metrics 

including root mean square error (RMSE), percent error, and 

days with zero differences are computed for these two sets 

of flows and are presented in total and by month and flow 

1

A water year is the 12-month period from October 1 to September 30. It is 

designated by the year in which it ends. 

percentile. Efforts are made to correlate the stability metrics 

with stream and basin characteristics.

Description of the Virginia Streamgage Network

 One hundred seventy-four real-time streamgages were 

active in Virginia as of September 30, 2013, the end of the 

study period (table 1, fig. 1). At that time, streamgages in Virginia were operated by three field offices, two USGS offices in 

Richmond and Marion, and a VDEQ office in Charlottesville. 

The VDEQ and, before it, the Virginia Water-Control Board, 

has been operating streamgages according to USGS specifications and protocols for decades. Data collected by both organizations are treated as interchangeable and as meeting the same 

quality standards. Streamgages are traded between the two 

organizations on an irregular basis related partly to operational 

considerations, such as funding and staffing, and to differences 

in the missions of the two agencies. No distinction is made 

between data collected by the two organizations in interpretive 

products, such as peak-flow and low-flow regression equations. The USGS opened a new field office in Leetown, West 

Virginia, in 2014, after the end of the study period.

Virginia’s environmental setting has been described 

in detail previously (Hayes, 1989; Nelms and others, 1997; 

Nelms and others, 2003). Aspects of the environmental setting discussed in those reports that are relevant to this study 

include physiography, elevation, land use, and interactions 

among them.

Streamgaging Operations

The USGS collects flow data using a clearly defined 

set of field and office procedures. Although procedures have 

changed through time, they have been documented since the 

1900s (Murphy and others, 1904; Corbett and others, 1943; 

Rantz and others, 1982; Sauer and Turnipseed, 2010; Turnipseed and Sauer, 2010). Development of stage-flow ratings and shifts (temporary ratings) that reflect controls and 

changes to them are a key part of the flow data collection and 

computation procedure. 

General Field and Office Procedures

Streamgaging field procedures have been developed to 

enable the USGS to collect complete and accurate stage data 

and maintain the stage-flow ratings, including documenting 

changes to it through time. This requires that hydrographers, 

the technicians and scientists who collect and compute flow 

data, make flow measurements and maintain streamgages at 

regular intervals.

Stage is recorded continuously using a variety of technologies. The USGS in Virginia measures stage using a variety 

of sensors, including stilling wells with float-driven recorders, 
Streamgaging Operations 3

03531500

03529500

03524000

03490000

03488000

03478400

03471500

03209000 03177710

03176500

03171000

03168000

03165000

02079640

02079241

02077000

02077500 02075045

02073000

02065500

02066000

02061500

02061000

02058400

02056650

02052000 02050000

02047500 02046000

02045500

02042500

02041650

02040000

02039500

02037500

02035000

02034000

02032640

01674500

01674000

01669520

01668000 01667500

01664000

01633000

01632082

03527000

03524500

03475000

03474000

03473000

03208950

03208500

03207800

03175500

03173000

03170500

03170000 03167000

03165500

03164000 02079500

02079490

02076000 02075500

02074500

02072500

02072000

02071900

02071530

02070000 02069700

02064000

02062500 02060500

02059500

02059485

02056900

02056000 02055000 02054530

02054500

02053800

02051500

02051190

02051000

02049500

02047370

02047000

02044500

02041000

02039000

02038850

02037705

02036500

02032250

02031000

02030500

02030000

02029000

01673800

01673550

01673000

01672500 01671100 01671025

01671020 01670400

01669000

01666500

01665500

01663500

01662800

01658500

01660400

01656000 01632900

01632000 01629500

01621050

01656903

01654500

01646305

01644280 01643880

01643700

01643590

01638480

01636690

01636316

01635500

01634500

01631000

01616100

01613900

01654000

01653000

01652545

01652500

01646000

01645762 01645704

01644000

01643805

01638420

01638350

01634000

01615000

0165389205

02055100

02028500

02027500

02027000

02026000

02025500

02024915

02024752

02024750

02024000

02022500

02021500

02020500

02019500

02018500

02018000

02016500

02016000

02015700

02014000

02011800

02011500

02011490

02011470

02011400

01628500

01627500

01626850

01626000

01625000

01620500

02017500

02013100

02013000

02011460

01622000

38°

39°

82°

80°

78°

76°

37°

Base from U.S. Census Bureau 1:500,000-scale digital data, 2015U.S. Geological Survey National Elevation Dataset, 2007National Hydrographic Dataset, 2005

EXPLANATION

5,7300

Elevation, in feet above 

the North American Vertical Datum of 1988

StreamLocation of streamgage 

and identifier

02021500

00

50

50

150 MILES

150 KILOMETERS

100

100

PIEDMONT

COASTAL

PLAIN

BLUE RIDGE

APPALACHIAN

PLATEAUS

VALLEY

AND

RIDGE

PhysiographicProvinces

Figure 1. Elevation, physiographic provinces, streams, and streamgages active as of September 30, 2013, in Virginia.
4 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

Table 1. Virginia streamgage numbers, names, drainage areas, locations, and elevations.

[mi2, square miles; dd, decimal degrees; ft, feet; —, undefined; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name Drainage area(mi2)

Latitude 

(dd)

Longitude 

(dd)

Elevation of gage

(ft)

01613900 Hogue Creek near Hayfield, VA 15.9 39.2145 -78.2881 669

01615000 Opequon Creek near Berryville, VA 58.2 39.1747 -78.0783 503

01616100 Dry Marsh Run near Berryville, VA 11.0 39.1926 -78.0686 501

01620500 North River near Stokesville, VA 17.3 38.335 -79.2392 2,051

01621050 Muddy Creek at Mount Clinton, VA 14.3 38.4868 -78.9603 1,360

01622000 North River near Burketown, VA 376 38.3404 -78.9136 1,103

01625000 Middle River near Grottoes, VA 373 38.2618 -78.8620 1,062

01626000 South River near Waynesboro, VA 127 38.0576 -78.9081 1,296

01626850 South River near Dooms, VA 148 38.0887 -78.8770 1,247

01627500 South River at Harriston, VA 212 38.2187 -78.8367 1,130

01628500 South Fork Shenandoah River near Lynnwood, VA 1,079 38.3226 -78.7547 1,002

01629500 South Fork Shenandoah River near Luray, VA 1,372 38.6462 -78.5347 722

01631000 South Fork Shenandoah River at Front Royal, VA 1,634 38.9140 -78.2108 469

01632000 North Fork Shenandoah River at Cootes Store, VA 210 38.6371 -78.8528 1,051

01632082 Linville Creek at Broadway, VA 45.7 38.6068 -78.8034 1,030

01632900 Smith Creek near New Market, VA 93.6 38.6935 -78.6428 881

01633000 North Fork Shenandoah River at Mount Jackson, VA 508 38.7457 -78.6389 839

01634000 North Fork Shenandoah River near Strasburg, VA 770 38.9768 -78.3361 493

01634500 Cedar Creek near Winchester, VA 102 39.0812 -78.3294 647

01635500 Passage Creek near Buckton, VA 86.5 38.9582 -78.2667 525

01636316 Spout Run at Rt 621 near Millwood, VA 21.4 39.0670 -78.0038 430

01636690 Piney Run near Lovettsville, VA 13.5 39.3108 -77.7185 397

01638350 South Fork Catoctin Creek at Rt 698 near Waterford, VA 31.6 39.1911 -77.6154 336

01638420 North Fork Catoctin Creek at Rt 681 near Waterford, VA 23.1 39.205 -77.6239 325

01638480 Catoctin Creek at Taylorstown, VA 89.5 39.2551 -77.5764 247

01643590 Limestone Branch near Leesburg, VA 7.88 39.1676 -77.5359 220

01643700 Goose Creek near Middleburg, VA 122 38.9865 -77.7967 327

01643805 North Fork Goose Creek at Rt 729 near Lincoln, VA 38.1 39.0723 -77.6839 295

01643880 Beaverdam Creek at Rt 734 near Mountville, VA 47.2 39.0377 -77.7223 307

01644000 Goose Creek near Leesburg, VA 332 39.0196 -77.5775 249

01644280 Broad Run near Leesburg, VA 76.1 39.0464 -77.4324 194

01645704 Difficult Run above Fox Lake near Fairfax, VA 5.49 38.8847 -77.3324 296

01645762 South Fork Little Difficult Run above Mouth near Vienna, VA 2.71 38.9089 -77.3383 274

01646000 Difficult Run near Great Falls, VA 57.8 38.9759 -77.2458 151

01646305 Dead Run at Whann Avenue near Mclean, VA 2.05 38.9598 -77.1757 178

01652500 Fourmile Run at Alexandria, VA 12.6 38.8433 -77.0859 29

01653000 Cameron Run at Alexandria, VA 33.9 38.8065 -77.1097 32

0165389205 Accotink Creek near Ranger Road at Fairfax, VA 3.99 38.8662 -77.2864 296

01654000 Accotink Creek near Annandale, VA 23.9 38.8129 -77.2283 191

01656000 Cedar Run near Catlett, VA 93.4 38.6368 -77.6250 199

01656903 Flatlick Branch above Frog Branch at Chantilly, VA 4.20 38.8824 -77.4319 257

01658500 South Fork Quantico Creek near Independent Hill, VA 7.62 38.5873 -77.4286 238

01660400 Aquia Creek near Garrisonville, VA 35.0 38.4904 -77.4336 120

01662800 Battle Run near Laurel Mills, VA 25.8 38.6557 -78.0739 375

01663500 Hazel River at Rixeyville, VA 285 38.5918 -77.9650 288
Streamgaging Operations 5

Table 1. Virginia streamgage numbers, names, drainage areas, locations, and elevations.—Continued

[mi2, square miles; dd, decimal degrees; ft, feet; —, undefined; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name Drainage area(mi2)

Latitude 

(dd)

Longitude 

(dd)

Elevation of gage

(ft)

01664000 Rappahannock River at Remington, VA 619 38.5307 -77.8136 252

01665500 Rapidan River near Ruckersville, VA 115 38.2807 -78.3400 439

01666500 Robinson River near Locust Dale, VA 179 38.3251 -78.0956 284

01667500 Rapidan River near Culpeper, VA 468 38.3504 -77.9750 241

01668000 Rappahannock River near Fredericksburg, VA 1,595 38.3085 -77.5292 70

01669000 Piscataway Creek near Tappahannock, VA 27.9 37.8771 -76.9005 1

01669520 Dragon Swamp at Mascot, VA 109 37.6338 -76.6963 22

01670400 North Anna River near Partlow, VA 342 38.0129 -77.7011 167

01671020 North Anna River at Hart Corner near Doswell, VA 462 37.8501 -77.4278 43

01671025 North Anna River above Little River near Doswell, VA 467 37.8257 -77.4261 35

01671100 Little River near Doswell, VA 107 37.8726 -77.5130 132

01672500 South Anna River near Ashland, VA 395 37.7968 -77.5489 83

01673000 Pamunkey River near Hanover, VA 1,078 37.7676 -77.3322 14

01673550 Totopotomoy Creek near Studley, VA 25.5 37.6626 -77.2578 38

01673800 Po River near Spotsylvania, VA 77.6 38.1715 -77.5947 184

01674000 Mattaponi River near Bowling Green, VA 256 38.0618 -77.3858 84

01674500 Mattaponi River near Beulahville, VA 603 37.8839 -77.1653 11

02011400 Jackson River near Bacova, VA 157 38.0423 -79.8814 1,639

02011460 Back Creek near Sunrise, VA 60.9 38.2454 -79.7687 2,200

02011470 Back Creek at Sunrise, VA 75.6 38.1904 -79.8117 1,968

02011490 Little Back Creek near Sunrise, VA 4.90 38.2146 -79.8376 2,638

02011500 Back Creek near Mountain Grove, VA 134 38.0696 -79.8970 1,701

02011800 Jackson River below Gathright Dam near Hot Spgs, VA 345 37.9485 -79.9492 1,400

02013000 Dunlap Creek near Covington, VA 162 37.8029 -80.0470 1,294

02013100 Jackson River below Dunlap Creek at Covington, VA 612 37.7887 -80.0006 1,206

02014000 Potts Creek near Covington, VA 153 37.7290 -80.0423 1,273

02015700 Bullpasture River at Williamsville, VA 110 38.1954 -79.5703 1,610

02016000 Cowpasture River near Clifton Forge, VA 461 37.7918 -79.7595 1,007

02016500 James River at Lick Run, VA 1,371 37.7737 -79.7845 978

02017500 Johns Creek at New Castle, VA 105 37.5062 -80.1067 1,254

02018000 Craig Creek at Parr, VA 329 37.6660 -79.9114 992

02018500 Catawba Creek near Catawba, VA 34.3 37.4682 -80.0053 1,300

02019500 James River at Buchanan, VA 2,073 37.5307 -79.6789 802

02020500 Calfpasture River above Mill Creek at Goshen, VA 141 37.9879 -79.4937 1,383

02021500 Maury River at Rockbridge Baths, VA 329 37.9074 -79.4220 1,100

02022500 Kerrs Creek near Lexington, VA 35.1 37.8257 -79.4431 980

02024000 Maury River near Buena Vista, VA 647 37.7626 -79.3914 846

02024752 James River at Blue Ridge Pkwy near Big Island, VA 3,076 37.5554 -79.3673 601

02024915 Pedlar River at Forest Road near Buena Vista, VA 27.1 37.6975 -79.2783 1,135

02025500 James River at Holcomb Rock, VA 3,256 37.5013 -79.2625 548

02026000 James River at Bent Creek, VA 3,649 37.5363 -78.8295 380

02027000 Tye River near Lovingston, VA 93.0 37.7154 -78.9817 575

02027500 Piney River at Piney River, VA 47.7 37.7024 -79.0275 632

02028500 Rockfish River near Greenfield, VA 94.8 37.8696 -78.8234 532

02029000 James River at Scottsville, VA 4,581 37.7974 -78.4914 252
6 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

Table 1. Virginia streamgage numbers, names, drainage areas, locations, and elevations.—Continued

[mi2, square miles; dd, decimal degrees; ft, feet; —, undefined; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name Drainage area(mi2

)

Latitude 

(dd)

Longitude 

(dd)

Elevation of gage

(ft)

02030000 Hardware River below Briery Run near Scottsville, VA 116 37.8126 -78.4553 295

02030500 Slate River near Arvonia, VA 226 37.7029 -78.3775 239

02031000 Mechums River near White Hall, VA 95.3 38.1026 -78.5928 430

02032250 Moormans River near Free Union, VA 77.0 38.1407 -78.5558 403

02032640 North Fork Rivanna River near Earlysville, VA 108 38.1635 -78.4247 365

02034000 Rivanna River at Palmyra, VA 663 37.8579 -78.2658 210

02035000 James River at Cartersville, VA 6,252 37.6710 -78.0858 164

02036500 Fine Creek at Fine Creek Mills, VA 22.4 37.5979 -77.8197 157

02037000 James River And Kanawha Canal near Richmond, VA — 37.5646 -77.5742 106

02037500 James River near Richmond, VA 6,753 37.5632 -77.5469 99

02038850 Holiday Creek near Andersonville, VA 8.54 37.4154 -78.6358 473

02039000 Buffalo Creek near Hampden Sydney, VA 69.6 37.2571 -78.4864 339

02039500 Appomattox River at Farmville, VA 302 37.3071 -78.3886 281

02040000 Appomattox River at Mattoax, VA 725 37.4215 -77.8589 175

02040892 Appomattox River at Route 602 near Mannboro, VA 942 37.3181 -77.8017 161

02041000 Deep Creek near Mannboro, VA 158 37.2832 -77.8697 177

02041650 Appomattox River at Matoaca, VA 1,342 37.2252 -77.4753 68

02042500 Chickahominy River near Providence Forge, VA 251 37.4363 -77.0608 5

02044500 Nottoway River near Rawlings, VA 317 36.9835 -77.7997 185

02045500 Nottoway River near Stony Creek, VA 577 36.9001 -77.3997 58

02046000 Stony Creek near Dinwiddie, VA 113 37.0671 -77.6025 130

02047000 Nottoway River near Sebrell, VA 1,441 36.7704 -77.1661 5

02047500 Blackwater River near Dendron, VA 290 37.0251 -76.8747 0

02049500 Blackwater River near Franklin, VA 613 36.7626 -76.8983 0

02051000 North Meherrin River near Lunenburg, VA 56.0 36.9974 -78.3497 334

02051500 Meherrin River near Lawrenceville, VA 552 36.7168 -77.8317 137

02052000 Meherrin River at Emporia, VA 744 36.6901 -77.5405 67

02053800 South Fork Roanoke River near Shawsville, VA 109 37.1401 -80.2664 1,362

02054500 Roanoke River at Lafayette, VA 254 37.2365 -80.2092 1,174

02054530 Roanoke River at Glenvar, VA 281 37.2679 -80.1395 1,100

02055000 Roanoke River at Roanoke, VA 384 37.2585 -79.9386 906

02055100 Tinker Creek near Daleville, VA 11.7 37.4176 -79.9353 1,212

02056000 Roanoke River at Niagara, VA 509 37.2551 -79.8714 820

02056650 Back Creek near Dundee, VA 55.8 37.2276 -79.8681 823

02056900 Blackwater River near Rocky Mount, VA 115 37.0451 -79.8442 876

02058400 Pigg River near Sandy Level, VA 351 36.9460 -79.5248 616

02059485 Goose Creek at Rt 747 near Bunker Hill, VA 125 37.2664 -79.5878 704

02059500 Goose Creek near Huddleston, VA 188 37.1732 -79.5203 593

02060500 Roanoke River at Altavista, VA 1,782 37.1046 -79.2953 502

02061000 Big Otter River near Bedford, VA 114 37.3640 -79.4192 670

02061500 Big Otter River near Evington, VA 315 37.2085 -79.3036 544

02062500 Roanoke (Staunton) River at Brookneal, VA 2,404 37.0394 -78.9457 351

02064000 Falling River near Naruna, VA 165 37.1268 -78.9597 412

02065500 Cub Creek at Phenix, VA 97.6 37.0793 -78.7636 370

02066000 Roanoke (Staunton) River at Randolph, VA 2,966 36.9151 -78.7408 308
Streamgaging Operations 7

Table 1. Virginia streamgage numbers, names, drainage areas, locations, and elevations.—Continued

[mi2, square miles; dd, decimal degrees; ft, feet; —, undefined; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name Drainage area(mi2)

Latitude 

(dd)

Longitude 

(dd)

Elevation of gage

(ft)

02069700 South Mayo River near Nettleridge, VA 85.5 36.5710 -80.1295 872

02070000 North Mayo River near Spencer, VA 108 36.5682 -79.9873 731

02071530 Smith River at Smith Riv Church near Woolwine, VA 26.3 36.7785 -80.2492 1,210

02072000 Smith River near Philpott, VA 215 36.7807 -80.0248 804

02072500 Smith River at Bassett, VA 259 36.7701 -80.0009 752

02073000 Smith River at Martinsville, VA 379 36.6612 -79.8806 657

02074500 Sandy River near Danville, VA 111 36.6196 -79.5042 460

02075045 Dan River at Stp near Danville, VA 2,116 36.5626 -79.3697 365

02075500 Dan River at Paces, VA 2,587 36.6424 -79.0895 322

02077000 Banister River at Halifax, VA 547 36.7765 -78.9158 316

02077500 Hyco River near Denniston, VA 288 36.5879 -78.8986 315

02079640 Allen Creek near Boydton, VA 53.5 36.6796 -78.3267 217

03164000 New River near Galax, VA 1,141 36.6473 -80.9790 2,208

03165000 Chestnut Creek at Galax, VA 39.4 36.6460 -80.9192 2,344

03165500 New River at Ivanhoe, VA 1,350 36.8348 -80.9526 1,942

03167000 Reed Creek at Grahams Forge, VA 258 36.9390 -80.8873 1,925

03168000 New River at Allisonia, VA 2,212 36.9376 -80.7456 1,848

03170000 Little River at Graysontown, VA 309 37.0376 -80.5567 1,816

03171000 New River at Radford, VA 2,767 37.1418 -80.5692 1,712

03173000 Walker Creek at Bane, VA 299 37.2682 -80.7095 1,666

03175500 Wolf Creek near Narrows, VA 223 37.3057 -80.8498 1,584

03176500 New River at Glen Lyn, VA 3,783 37.3729 -80.8606 1,490

03177710 Bluestone River at Falls Mills, VA 44.3 37.2715 -81.3048 2,310

03207800 Levisa Fork at Big Rock, VA 297 37.3537 -82.1957 866

03208500 Russell Fork at Haysi, VA 286 37.2071 -82.2957 1,238

03208950 Cranes Nest River near Clintwood, VA 66.5 37.1240 -82.4388 1,440

03209000 Pound River below Flannagan Dam, near Haysi, VA 221 37.2371 -82.3432 1,200

03471500 South Fork Holston River at Riverside, near Chilhowie, VA 76.6 36.7604 -81.6312 2,107

03473000 South Fork Holston River near Damascus, VA 303 36.6518 -81.8440 1,792

03474000 Middle Fork Holston River at Seven Mile Ford, VA 132 36.8073 -81.6221 1,960

03475000 Middle Fork Holston River near Meadowview, VA 206 36.7132 -81.8187 1,820

03478400 Beaver Creek at Bristol, VA 26.9 36.6318 -82.1337 1,781

03488000 North Fork Holston River near Saltville, VA 221 36.8968 -81.7462 1,704

03490000 North Fork Holston River near Gate City, VA 671 36.6087 -82.5679 1,198

03524000 Clinch River at Cleveland, VA 533 36.9448 -82.1549 1,925

03524500 Guest River at Coeburn, VA 87.2 36.9293 -82.4563 1,926

03527000 Clinch River at Speers Ferry, VA 1,123 36.6487 -82.7504 1,196

03529500 Powell River at Big Stone Gap, VA 112 36.8690 -82.7754 1,458

03531500 Powell River near Jonesville, VA 319 36.6620 -83.0949 1,259
8 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

bubble gages with submersible and non-submersible pressure 

transducers, and non-contact radar and acoustic sensors (Sauer 

and Turnipseed, 2010). When installed and maintained properly, both stage measurement systems can be used to collect 

stage data accurate to within 0.01 foot or 0.2 percent of the 

effective stage, whichever is greater. In general, a bubble gage 

and transducer may be installed more quickly and for a lower 

cost than a stilling well, but a bubble gage and transducer may 

need to be replaced more frequently during the lifetime of 

the streamgage. 

Flow measurements are made to develop ratings at new 

sites and to document changes to them once established. 

Routine trips are frequent enough to characterize the stageflow relation for low, medium, and moderately high flows. 

Extra visits are made to measure floods, which are infrequent 

and are of particular interest to major national institutional 

stakeholders. Additionally, the relation between flood stage 

and flow typically remains stable for years or decades. Water 

velocity is measured with either a Price-type vertical axis 

mechanical current meter or a hydroacoustic Doppler velocimeter, a class of instrument that includes Acoustic Doppler Current Profilers. In wadeable streams, either type of meter may 

be deployed from a wading rod, which is also used to sound 

depth. At nonwadeable flows, hydroacoustic velocimeters are 

deployed on a custom-made boat that is towed across the river 

from a bridge, cableway, or boat, and depth is measured using 

a sonic sounder incorporated into the meter. If a mechanical 

meter is used, it is deployed with sounding weights from a 

cable lowered from a bridge, cableway, or boat, and the depth 

is read from a dial attached to the cable reel. 

The principal field tasks for streamgaging are measuring 

flow and maintaining stage sensors and related equipment and 

structures. Some tasks are done about annually, such as differential leveling from gage features to benchmarks to ensure 

that instruments or bubble gage orifices have remained physically stable and therefore are capable of recording accurate 

stage data. Other maintenance tasks need to be done more 

frequently; the necessary frequency varies according to site 

conditions, such as sediment load and deposition patterns. A 

routine site visit includes checking the recording gage against 

a non-recording reference gage, flushing intakes at stilling 

wells, repairing or replacing any equipment that has malfunctioned, and a control inspection. 

Documentation of control inspections provides a record 

of changes to the control through time. This documentation is 

critically important for interpreting rating changes. Common 

changes to controls include scour and fill during rises in flow, 

growth and death of macrophytes and algae, and accumulation 

and removal of leaves or large woody debris. Less common 

changes that may be large in magnitude include those caused 

by humans or animals placing material on or removing material from the control; some of the largest rating changes at low 

flow result from dams built by beavers or swimmers. Several 

of these types of changes are clearly temporary. Changes to 

a control related to scour and fill may be either short term or 

long term, and the judgment about how long to expect such a 

change to remain typically is made in light of previous experience with the site and magnitude of the change.

Flow Data Computation

Flow data computation is complex and includes several 

steps that are done manually and involve data interpretation on the part of the hydrographer. Quality assurance of 

stage data is necessary but usually simple. When it is not 

simple, the aspects of the stage record that require the most 

interpretation involve records affected by sediment deposition on intakes or orifices, equipment malfunctions, or errors 

resulting from the movement of stage sensors as discovered 

through differential leveling. Stage sensors move rarely, such 

as during a major flood, but when they do, correcting the 

record requires extensive work. Equipment is much more 

reliable than it was historically but might still malfunction at 

a few sites operated by any specific field office during a year. 

In contrast, sediment deposition is common and unavoidable 

in some streams, particularly low-gradient streams where 

the streambed includes substantial amounts of clay, silt, and 

sand. Correcting stage records affected by deposition requires 

extensive interpretation. 

Development and maintenance of the rating curve is fully 

interpretive. Rating curves are empirical, and curve fitting is 

done graphically. Most streamgages have simple controls, for 

which stage is a simple function of flow; however, for some 

streamgages, control is a function of rate of variable backwater, tide, or some other characteristic. At streamgages with 

simple controls, the rating curve is a graphical depiction of 

the stage-flow relation for a specific hydraulic control, typically a natural feature such as a channel constriction, change 

in streambed slope, or the aggregate characteristics of channel slope and roughness. Where the feature in question is a 

weir or a bedrock ledge, or is formed from bedrock and large 

boulders, the control typically changes infrequently, and office 

work related to the rating may be straightforward. Where the 

feature is formed from small boulders, cobbles, sand, fine 

materials, or a mixture of substrates, the control may change 

frequently and require extensive office work to analyze the 

stage-flow relation. 

Each measurement is evaluated carefully, first in the field, 

where it is initially plotted on the rating curve, and later in 

light of successive measurements. Measurements that plot off 

the curve by more than the expected percentage require a new 

rating, a shift, or an explanation for the error of the measurement. A shift is a temporary rating curve, which is typically 

a modification of the base rating curve for part of its range in 

stage. The decision on whether to respond to a change to a 

control by using a shift or a new rating involves determining 

when the control changed, the nature of the change, and how 

long the change lasted or is expected to last. A new base rating 

is essentially impossible to develop on the basis of a single 

measurement, even in cases such as obvious large changes to 
Streamgaging Operations 9

controls following major floods. However, a rating may be 

developed as the necessary measurements become available, 

and when complete, the rating can be backdated to the time of 

the actual change to the control. In this case, provisional data 

displayed on the web will be processed using a series of shifts, 

but the final “approved data” will be processed using the final 

rating. Often, the provisional data are corrected during review. 

The office procedures the USGS has historically used for 

computing flow data include several steps of review, any of 

which may result in corrections. Substantial changes to initial 

data are common, including to provisional data that previously 

have been posted online and used by the public. 

The development of shifts and ratings are discussed in 

an internal document, the station analysis, which is prepared 

for each streamgage every year and archived permanently. 

The station analysis comprehensively details changes in stage 

datums; the adjustment and correction of stage data, including corrections applied as a result of documented sensor drift; 

the nature and condition of the channel controls, including 

changes in the location, shape, composition, and roughness of 

the control; the shape and historical stability of the resulting 

ratings; the number, quality, and range of the flow measurements and their relation to the rating in terms of coverage of 

stage and time; and the detection of shifts and the adjustment 

of them to account for control changes. The station analysis 

also documents efforts to compare the resulting flow records 

to flow records collected for other locations on the same or 

nearby streams, as well as to other hydrologic or meteorological information (such as rainfall or temperature records). 

Lastly, the station analysis documents the subjective quality 

assessment of the hydrographer who computes the record and 

prepares the station analysis. 

The station analysis and all of the elements of the flow 

record are reviewed by a colleague hydrographer, the office 

chief or supervisor, and often one or more hydrographers 

from another office or other technical specialists. The Virginia 

Water Science Center of the USGS also runs various computer 

scripts that scan the record for outliers and inconsistencies, the 

rating and shifts for unusual or hydraulically unsound shapes 

and changes. All of these steps contribute to the production of 

a reliable and defensible “approved” flow record, but few of 

the steps were applied prior to the automatic posting of “provisional” record.

To help guide individual hydrographers and to instill 

more consistency in local practices, the USGS requires each 

Water Science Center to develop a single, comprehensive 

quality-assurance plan for surface-water activities within the 

center, including its streamgaging operations. The document 

provides guidance on the need for measurements, guidance on 

parameters for measurement frequency and range, and instructions about which control, measurement, and instrumentation 

factors to consider when conducting fieldwork or processing 

records, including rating development and shift applications. 

The document also establishes requirements for training of 

hydrographers and the review of their work.

The quality of the flow record is assessed and recorded in 

Water Year Summaries, which have replaced Site Data Sheets, 

which had previously replaced Annual Water-Data Reports 

(U.S. Geological Survey, 2016a). The assessment reflects the 

judgment of hydrographers from the station analysis. These 

qualitative assessments are among the information that USGS 

publishes to the Water Year Summaries, but the assessments 

are not captured in the National Water Information System or 

related electronic databases. Therefore, the assessments are 

difficult to incorporate in quantification studies.

Although the USGS has made standardizing record 

processing a priority, the processing has retained elements of 

a craft. Individual judgment is part of the process. Different 

analysts may achieve the same results using slightly different methods. For the purposes of this study, these differences 

matter because, by design, criteria for developing a shift 

overlap with criteria for developing a new rating. A shift is to 

be applied when in the hydrographer’s judgment the rating 

change is temporary, in contrast to a new rating, which is to 

be developed when a change to a control is permanent (or has 

reached equilibrium). In practice, hydrographers make judgments differently about whether a measured change is temporary or permanent. Some will develop a new rating as soon as 

enough measurements have been made to define the change, 

whereas others will apply a shift for several years, adjusting 

it as needed, to see whether the control changes back. Some 

hydrographers might apply and adjust shifts for years or even 

decades through a series of bed changes without changing 

the base rating. These analytical differences make little if any 

difference to the published flow data but complicate efforts to 

use the number and frequency of rating changes to compare 

stability among sites and through time. 

The USGS has implemented “continuous records processing,” a procedure in which data are processed immediately 

upon the return of hydrographers to the office from a field trip. 

In 2014, the USGS Office of Surface Water (OSW) issued 

Technical Memorandum 2014–08, which calls for all USGS 

Water Science Centers to correct time-series stage and flow 

data and enter flow measurements into the National Water 

Information System Web (NWIS-Web) database within 2 business days of a field measurement. Computed real-time data on 

NWIS-Web that do not match the flow measurement within 

its rated accuracy are to be corrected or removed from public 

display (Robert Mason, U.S. Geological Survey, written commun., July 14, 2014, https://hydroacoustics.usgs.gov/memos/

OSW2014-08.pdf). Even after continuous records processing 

has been fully implemented, however, uncertainty will remain 

as to the accuracy of provisional flow data. The accuracy of 

provisional flow data depends on several factors, including 

quality and promptness of field and office work, the quality of 

the stage record, and the stability of the rating.

Hydrographers are forced to make judgments about the 

timing of rating changes and shifts. When the change in rating 

can be associated plausibly with a distinct rise in flow, most 

hydrographers attempt to start the new rating to coincide with 
10 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

peak flow. When this is not practical, ratings will begin on 

convenient but arbitrary dates. Some hydrographers prefer to 

change base ratings relatively frequently and attempt to associate the start time with a hydrologic event. Others will change 

base ratings at convenient times and use shifts before and after 

the base-rating change to make a smooth transition. A great 

deal of care is taken to look for a plausible event for the beginning of shifts, regardless of the approach used for the timing 

for base-rating changes. A scour shift typically begins while 

flow rises, and a fill shift begins while flow recedes. This 

practice is based on an extensive body of empirical evidence 

from flow measurements made across rises in flow at many 

streamgages (Rantz and others, 1982).

Monthly field measurements were standard from the 

beginning of continuously recorded stage until telemetry or 

satellite data transmissions became widely used in the 1980s. 

At that time, adoption of the new technology, which enabled 

hydrographers to know whether stage was being recorded, 

coincided with increased budgetary pressures. The USGS did 

a series of studies in most states during the 1980s intended to 

optimize network design. The studies were modeled after work 

done in the Lower Colorado River Basin (U.S. Geological 

Survey, 1998; Moss and Gilroy, 1980). Primary considerations 

were cost effectiveness, minimizing lost record, and characterizing rating changes. An algorithm was developed that allowed 

the tradeoffs between various options to be quantified as their 

contributions to the standard error of mean annual flow. This 

algorithm was applied on a state-by-state basis, and the results 

were aggregated nationally. This led to the determination that 

for most states, the optimal tradeoff between cost and accuracy 

for a typical streamgage was a frequency of 6–8 site visits per 

year. More measurements are made for streamgages where 

beds are extremely unstable, such as those with sand beds, or 

at locations where consequences of error are great, such as the 

Colorado River at the United States–Mexico border (Wahl and 

others, 1995; Anning, 2001).

Ratings and Shifts for Streamgages in 

Virginia through 2013

Availability of ratings and shifts varied by streamgage, 

largely because archival methods varied by field office and 

immediate operational needs (tables 2 and 3, at end of report). 

Although mean daily flow values have been computed in 

NWIS since the adoption of the database, different Water Science Centers and field offices have archived different amounts 

of ancillary data, such as ratings and shifts, throughout the 

1980s, 1990s, and into the 2000s. Archiving of all shifts and 

ratings did not become universal and mandatory until the 2002 

water year. Rating availability exceeded shift availability. 

During the study period, 643 base ratings were available 

in the database (table 4, at end of report). In this report, “the 

database” refers to the Virginia node of the NWIS. Unless 

another state is specified, references to NWIS also refer to the 

Virginia node. 

Base ratings are each stored as a separate file, and all files 

include explanatory comments. Therefore, base ratings are 

straightforward to inventory. Shifts are stored in a more complicated fashion than ratings. All shifts for each site are stored 

together in a table. Each shift is stored as multiple entries with 

varying numbers of fields per shift and varying amounts of 

metadata, depending on when the shift was created and the 

nature of the shift. Because all shifts were associated with 

beginning dates and times, the simplest way to inventory them 

was to filter them by time.

Many of the shift entries, however, represent the same 

shift entered for multiple beginning times, and there is no 

straightforward way to identify and group them. The number of points needed to define a shift varies. The magnitude 

of an individual shift frequently varies during the course of 

the shift. More than one shift can be in effect simultaneously 

at different parts of the rating. Comments for some entries 

indicate that the shift is continued unchanged when the record 

is being updated. Some shift entries exist solely for transitions 

across the water year (from September 30 to October 1). Some 

hydrographers also follow a practice of creating, entering, and 

implementing shifts of zero value in order to compute flow 

values directly from the base rating, instead of ending the 

previous shift. Had the entire set of shifts included comments, 

repeated shifts probably could have been reliably identified. 

With incomplete explanatory information, however, retrospectively relating shifts with hydrologic events in bulk can be 

done only imprecisely. 

October 1, at the beginning of the water year, was the 

most common date for implementing a rating; 161 ratings 

began on October 1 of one year or another (table 5). Another 

157 ratings were put into effect on the date of a measurement. 

(Twice, a rating started on an October 1 when a measurement 

was made.) Most of these were probably convenient dates to 

convert a shift to a new rating, although 46 of the measurements were made on days with peaks, either floods or highflow pulses, or flow events smaller than floods when flow rose 

but stayed within the channel. Sixty-two ratings were already 

in effect on October 1, 1990. Another two ratings were put 

in effect on a date with no approved daily flow value; these 

were dates before the associated streamgage was activated 

or reactivated. Of beginning dates with approved daily flow 

values, 199 came on peaks, either floods or high-flow pulses, 

and another 23 came on days when flow exceeded the 10-percent duration (D10). The remaining 217 ratings began on dates 

when no measurement was made, flow was less than the D10, 

and no peak was evident in the daily flow record. 

About 23,000 shifts with unique beginning times were 

available for water years 1991–2013 (table 3). This set 

includes shifts that began before water year 1991 or before a 

streamgage was fully active, but the shifts were still in effect 

when the flow data used in this study were collected. Of the 

available shifts, 6,273 began on days when more than one 
Ratings and Shifts for Streamgages in Virginia through 2013 11

Table 5. Selected characteristics of daily flows on days that base ratings began at streamgages 

in Virginia, water years 1991–2013.

[<, less than; >, greater than; D10, flow exceeded or equaled on 10 percent of days; italicized entry is a subcategory 

of the preceding category; Categories are not mutually exclusive, individual ratings may belong to more than one 

category, and columns are not intended to add up to the total]

Category Days shifts began

Number Percentage

Total 643 100

Began on a peak, including high-flow pulses 199 31

In effect on October 1, 1990 62 10

Put in effect during the study period, but before daily value record began 2 0

Began October 1, total 225 35

- No peak on 9/30 or 10/1 223 35

Began on a day with flow >D10, on rise or recession but not peak 23 4

Began on any day when a measurement was made 157 24

- Flow >D10 24 4

- On a peak 46 7

- Not on a peak, and flow <D10 105 16

Other 217 34

shift began. The maximum number of shift entries, 32, came 

on a day when a measurement was made and a beaver dam 

subsequently was removed from a control over a period of 

several hours (October 4, 2005, at 01671100, Little River near 

Doswell, VA). 

Setting aside the multiple shifts made on the same day at 

the same site, there were records for days with 16,853 unique 

shifts beginning at streamgages during water years 1991–2013 

(table 6). Forty-one percent of shifts (6,842) began on days 

when the daily flow record showed a peak. These peaks 

included floods and high-flow pulses. For this analysis, a fairly 

liberal definition of a high-flow pulse was used: flow on a day 

that was greater than flow on either of the two preceding days 

or the subsequent day. Additionally, the days following rises in 

flow were identified and tallied separately, and generally represent days when a peak was receding; 7 percent of days when 

shifts began (1,144) were the days following peaks. 

Because shifts were developed using unit flow values, not 

daily flow values, flagging flow events using daily values can 

result in some errors related to time resolution. For instance, 

comments associated with shifts indicated that many began 

on a rise that peaked during the evening or night when the 

daily value for the following date was greater than the daily 

value on the date of the peak. More than a thousand shifts 

began on days of high flow although not on the peak. Seven 

percent of shifts began on such days when flow exceeded the 

D10 (1,135), and about 1 percent of those (168) began on days 

when flow exceeded the 1-percent duration flow (D1). These 

shifts were not necessarily intended to begin on the peak. 

Scour shifts often begin at the start of the rise and are in full 

effect at the peak, whereas fill shifts begin on the peak and are 

prorated through the recession.

Not all shift beginnings were clearly associated with an 

event. October 1, the first day of the water year, was ordinarily 

a convenient but arbitrary day to begin a shift. It was a common begin date for a set of shifts filtered to one per day; 5 percent (797) of the 16,853 shifts began on October 1 (table 6). 

Many shifts began the day that a measurement and streamgage 

inspection was made; 34 percent (5,681) of shifts began on 

these days. However, many of the measurements were made 

on days of peaks and high flows; 602 of the measurements 

were made on days when flow exceeded the D10, and 1,365 

began either on the day of a peak or the day following a peak. 

There was overlap between days of peaks and days of high 

flows, but the upshot is that 24 percent of shifts began on days 

when a measurement was made, not on a peak or the day after 

a peak, and when flow was less than the D10. Shifts begun 

on days of medium or low flow and without peaks were not 
12 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

Table 6. Selected characteristics of daily flows on days that shifts began at streamgages in 

Virginia, water years 1991–2013.

[<, less than; >, greater than; D1, flow exceeded or equalled on 1 percent of days; D10, flow exceeded or equalled 

on 10 percent of days; italicized entry is a subcategory of the preceding category; Categories are not mutually exclusive, individual shifts may belong to more than one category, and columns are not intended to add up to the total]

Category Days shifts began

Number Percentage

Total 16,853 100

Began on a peak, including high-flow pulses 6,842 41

Began the day after a peak 1,144 7

Began October 1, total 797 5

- No peak on 9/30 or 10/1 572 3

Began on a day with flow >D1, on rise or recession but not peak 168 1

Began on a day with flow <D1 but >D10, on rise or recession but not peak 967 6

Began on any day when a measurement was made 5,681 34

- Flow >D10 602 4

- On a peak 831 5

- Day after a peak 534 3

- Not on a peak, and flow <D10 4,024 24

Other 3,136 19

necessarily arbitrarily associated with the measurement date. 

Controls are sometimes cleaned during streamgage inspections, which in turn results in one or more shift entries showing a return to the base rating. In the case of scour or fill shifts, 

it would be common (if not universal) practice to make a shift 

entry the day of the measurement for an existing shift, even 

when the shift was carried without change. 

Frequently, shifts began at multiple streamgages on the 

same date, which also demonstrates the effort made to associate shifts with hydrologic events (table 7). The maximum 

number of streamgages with shifts beginning on the same 

date was 87, on October 1, 2010, a day when, in addition to 

being the beginning of the water year, 52 streamgages had a 

high-flow pulse, 38 had flow between the D10 and D1, and 9 

had flow exceeding the D1. On 41 days, shifts began at 30 or 

more streamgages. Of those days, 11 were October 1 of one 

year or another, including several years when flow was high 

at several streamgages on October 1. The greatest number 

of streamgages with shifts beginning on a different date, 63, 

came on January 31, 2013. 

Determining the precise number of days on which shifts 

are in effect was impractical because of the complexity of 

the shift dataset in combination with an incomplete set of 

explanatory comments. The shift dataset includes shifts of 0 

feet that were created and put in place for the convenience 

of hydrographers at a particular site, some of which include 

comments to the effect that the rating was used directly for 

the designated period. Additionally, more than one shift could 

be in effect at different points on the rating at the same time. 

Unraveling the shift process might have been done with more 

complete electronic documentation.

Timing of record working changed markedly during 

1991–2013 (figs. 2 and 3). The relation of the start dates of 

shifts to dates of the final modification gives an approximate 

idea of when the record was worked and represents the best 

means available to estimate, in general, when the various 

shifted ratings used in this study were likely to have been 

developed and implemented. 

During the early 1990s, record working was done 

primarily on an annual basis during a distinct office season, 

winter and spring (fig. 2). Few records were worked during the summer and fall when streamgage maintenance was 

done. From 1991 through 2001, the median number of days 

between the start date of the shift, the first date of data for 

which it was intended to modify, and the date it was created 

in the office by a hydrographer, fluctuated between about 240 

and about 300 days. The 75th percentile of days between start 

date and creation date of shifts was more than 365 for every 

year during that period. Beginning in 2002, in recognition of 

the growing importance of near-real-time flow data to data 
Ratings and Shifts for Streamgages in Virginia through 2013 13

Table 7. Dates on which shifts began at 30 or more streamgages, and flow characteristics for that day at the 

streamgage in question in Virginia, water years 1991–2013.

[<, less than; >, greater than; D10, 10-percent flow equalled or exceeded 10 percent of the time; D1, flow equalled or exceeded 1 percent 

of the time; DV, daily value or mean daily flow]

Date

Flow characteristic on the given date Total number 

of streamgages 

for date <D10 D10<DV<D1 >D1 Peak or 

high-flow pulse

One day 

after peak

10/1/2010 40 38 9 52 2 87

10/1/2007 83 0 0 2 6 83

1/31/2013 22 9 32 25 2 63

10/1/2006 58 1 0 11 32 59

10/1/2009 58 0 0 0 2 58

6/28/2006 4 23 30 45 2 57

10/27/2007 33 18 2 34 2 53

10/1/2002 53 0 0 0 1 53

10/1/2008 49 0 0 2 5 49

11/20/2003 1 17 30 33 0 48

9/19/2012 32 15 0 32 1 47

11/30/2005 9 19 19 29 0 47

12/8/2011 3 20 23 28 0 46

5/8/2013 9 16 20 25 1 45

12/1/2010 8 22 14 38 0 44

7/8/2005 15 14 15 35 0 44

2/23/2003 0 2 42 30 1 44

12/12/2008 17 21 3 25 0 41

5/7/2013 20 11 7 9 0 38

10/1/1997 38 0 0 6 16 38

1/15/2013 35 2 0 0 0 37

9/27/2009 28 7 1 24 0 36

10/30/2012 10 5 20 25 0 35

10/1/2001 35 0 0 2 2 35

4/23/2006 11 20 3 22 0 34

4/16/2007 1 20 13 27 0 34

1/16/2013 16 10 7 14 2 33

12/2/2010 5 24 4 24 0 33

10/9/2005 8 9 16 30 0 33

2/7/2004 2 20 11 18 0 33

12/27/2012 11 18 2 23 0 31

3/29/2005 0 16 15 19 2 31

9/29/2004 0 0 31 29 0 31

10/1/2004 9 20 2 3 13 31

4/14/2004 0 22 9 22 0 31

10/15/2001 30 1 0 17 0 31

10/1/1994 31 0 0 1 0 31

3/1/2012 7 18 5 20 0 30

10/1/2003 27 3 0 0 1 30

11/13/2002 3 26 1 25 1 30

10/1/1999 14 7 9 22 2 30

Subtotals 835 494 395 828 96 1,724

Totals for all dates 

at all sites

11,085 3,691 2,002 6,842 1,144 16,853
14 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

users, a greater effort was made to work records continuously. The median delay between the start date of a shift and 

its final modification decreased by about 4 months from 2001 

to 2002 (fig. 3). Even so, many records required review and 

revision after more data had been collected, and one-quarter 

or more of shifts had delays of 3 months or more through 

2013. During water years 1991–2013, one-half of the shifts 

had a delay between start date and final modification of about 

60 days only in 2012 and 2013. Because 60 days is close to 

the 8-week interval between routine streamgage visits, these 

2 years represent the first time when the expanded shifted 

rating saved in the database was more likely than not to be the 

one used to generate provisional data served to the internet. 

Even in those years, though, more than one-quarter of shifts 

were modified 90 days or more after the shift’s beginning 

date. Because defining a shift that affects the stage-flow 

relation through a range of flows requires multiple measurements made during multiple trips, there will be limits to how 

quickly shifts can be completed, even with the most diligent 

efforts possible to work records continuously.

Vertical and horizontal banding is evident in the plot of 

shift start dates relative to final modification dates (fig. 2). 

Horizontal bands represent days when large numbers of shifts 

were put into effect on the same day; these might be days 

when many shifts were approved but are artifacts of data computation. Vertical bands are more interesting. Because they 

represent days when many shifts began, vertical bands signify 

the days when hydrographers identified a hydrologic event 

likely to have altered the control and caused a shift at multiple 

streamgages. Vertical gaps represent periods when hydrographers judged that no events took place at any streamgages that 

changed controls and required a shift.

10/01/1989

10/01/1994

10/01/1999

10/01/2004

10/01/2009

10/01/2014

10/01/1989 10/01/1994 10/01/1999 10/01/2004 10/01/2009 10/01/2014

Shift start date

Date of final shift modification

Figure 2. Relation between start dates of shifts and dates of 

final modification of shifts at streamgages in Virginia, water years 

1991−2013.
Ratings and Shifts for Streamgages in Virginia through 2013 15

30 days

90 days

180 days

1 year

2 years

3 years

Days between shift start date and shift final modification

Shift start date, grouped by calendar year

1990 1995 2000 2005 2010 2013

0

100

200

300

400

500

600

700

800

900

1,000

1,100

1,200

EXPLANATION

75th percentile

25th percentile

Median

The largest value that does not exceed the 75th percentile

plus 1.5 times the interquartile range

Outlier

The smallest value that is no less than the 25th percentile

minus 1.5 times the interquartile range

Figure 3. Number of days between start and final modification of shifts at streamgages in Virginia, 1990–2013.
16 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

Patterns in the Stability of Stage-Flow 

Relations

Ratings change through time as hydraulic controls 

change. Minor changes are common and are the principal 

reason for repeated flow measurements made at a streamgage. 

Major changes are caused by disruptive events, such as major 

floods; human activities, such as channel reconfiguration or 

bridge construction that change streambeds and banks; or even 

deliberate events such as moving the streamgage or building 

or removing a weir. Some disruptive events are random. Some 

may be nonrandom but difficult to anticipate or avoid when 

streamgage locations are selected.

Patterns of streamgage ratings through time may be 

thought of as punctuated equilibria. Disruptive events and 

resulting major changes are relatively rare. Streamgage ratings 

commonly remain at equilibrium for years or decades between 

the disruptive events. The length of periods of equilibrium, 

and routine departures from them, are of primary interest in 

this discussion of rating stability and the manner in which it 

relates to the reliability of streamgages during routine periods.

This analysis was done in an iterative manner. The following sections discuss major parts of this analysis. Flow 

measurements were plotted and curves were fitted through 

them. Residuals from the curves (the difference between 

the observed and predicted value of the dependent variable) 

were plotted as a time series. Patterns in the time series were 

compared to patterns in the scatter plots, and major changes 

were noted. These major changes were used to define “rating 

families” or series of ratings and shifted ratings representing 

periods of equilibrium. Curves were then fitted through the 

rating families, and time series of the residuals were used to 

check their identification and refine their designations.

Ratings and shifts are depictions of the stage-flow relation and are developed from flow measurements. Much of the 

analysis in this section was done using flow measurements. 

Flow measurements are the only available method to quantify the shiftiness of controls, although certain types of shifts 

can be developed in the absence of flow measurements. Leaf 

shifts, for instance, are needed for streams flowing through 

deciduous forests when autumn leaves fall from the trees into 

the stream and accumulate into a leaf mat on a streamgage 

control. These leaf mats typically remain in place until a highor moderately high-flow episode washes them off the control. 

They can be detected on real-time hydrographs in the absence 

of flow measurements, as a gradual, multiday rise in stage in 

the absence of precipitation, in Virginia, during October or 

November. Leaf mats form during a season when flows are at 

or near annual lows.

In an iterative process, a LOESS curve was fit through 

all available flow measurements for all the streamgages in 

Virginia’s real-time network as of September 30, 2013, with 

at least 20 flow measurements with positive flow values. This 

curve served as an average long-term rating. For each measurement with a positive flow value, residuals from the curve 

were calculated. Measurements with negative or zero flow values were not considered as part of this analysis because these 

values do not exhibit consistent stage-flow relations.

A set of plots was developed showing three plots for each 

streamgage: (1) gage height and flow for all the measurements 

and the LOESS curve, (2) the residuals plotted by date, and 

(3) the residuals plotted by Julian date (appendix 1). Curves 

were fit and plotted using R, ggplot2, and plyr (R Core Team, 

2014; Wickham, 2009; Wickham, 2011). Residuals by date 

were used to explore long-term trends, and residuals by Julian 

date were used to explore seasonal trends. Printouts of the 

plots grouped by major river basin or by field office assignment were taken to the three streamgaging field offices active 

in Virginia: the USGS field offices in Richmond and Marion 

and the VDEQ field office in Charlottesville. Hydrographers 

were interviewed about the streamgages with which they were 

familiar, and notes and sketches were made on the printouts 

to describe the rating characteristics, measurement quality, 

streamgage history, and other factors that the hydrographers 

considered important about the streamgages. The interview 

information was compiled and merged with descriptive 

information available from USGS databases (table 8, available 

online). These plots and statistics were also used to identify 

and explain major outliers.

Development of Long-Term Average Ratings

To evaluate long-term stage-flow relations, curves were 

fitted through points representing all available flow measurements. Different curves were compared. Periods when the 

relation changed little were determined, and curves were then 

fitted through points representing flow measurements from 

these periods.

Comparison of Smoothing Curves

The LOESS curves that initially were fitted through the 

measurements fitted poorly and resulted in time-series plots 

that in some cases were dominated by obvious artifacts of 

fitting. Different smoothers were then compared to achieve a 

better fit (fig. 4): (1) linear regression in logarithmic space, (2) 

Gaussian LOESS with span=0.5, (3) symmetric LOESS with 

span=0.5, (4) symmetric LOESS with span=0.75, (5) symmetric LOESS with span=0.25, and (6) generalized additive model 

(GAM).This comparison was done for all rating families in 

the study, although a single representative site, 01634000, 

North Fork Shenandoah River at Strasburg, was chosen to 

illustrate the differences in smoothers (fig. 3). In general, small 

changes in span made small differences to the pattern and fit 

of the curves, and the settings used in these plots were broadly 

representative of ranges of span. The differences between the 

two families of LOESS curves were not great. The “symmetric” family tended to fit these data slightly better than the 

“Gaussian” family, but in general, both families had many of 

the same weaknesses. 
Patterns in the Stability of Stage-Flow Relations 17

A. Linear regression B. LOESS, gaussian, span = 0.5

C. LOESS, symmetric, span = 0.75 D. LOESS, symmetric, span = 0.5

E. LOESS, symmetric, span = 0.25 F. Generalized additive model (GAM)

1

5

10

20

35

Gage height, in feet

1

5

10

20

35

Gage height, in feet

1

5

10

20

35

Gage height, in feet

Flow, in cubic feet per second Flow, in cubic feet per second

20 100 1,000 10,000 100,000 20 100 1,000 10,000 100,000

Figure 4. Rating curves for stage-flow relations for streamgage 01634000, North Fork Shenandoah River 

at Strasburg, VA, with six smoothers applied: A, linear regression, B, Gaussian LOESS, C, LOESS, 

symmetric 0.75, D, LOESS symmetric 0.5, E, LOESS, symmetric 0.25, and F, generalized additive model. 

Shading represents 99-percent confidence interval.
18 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

The span of a LOESS curve is a measure of how localized the curve is. A small value of span represents a highly 

localized curve, which uses relatively few of the points in the 

plot and only those closest to that section of the data. Values 

of span less than 1 correspond to the proportion of points that 

is used for computing the regression. At a span of 1, all the 

points in the plot are used, although they are weighted. With 

an infinite span, all points are used without weights so that it is 

functionally a linear regression. A GAM is a generalized linear 

model in which the linear predictor is given by a user-specified 

sum of smooth functions of the covariates plus a conventional 

parametric component of the linear predictor; models are fitted 

by penalized likelihood maximization, in which the model 

likelihood is modified by the addition of a penalty for each 

smooth function (Wood, 2011, 2014).

The fit of the LOESS curves to these data varies, but 

many are poor. Fit through the high measurements was 

systematically poor with, as an example, the various LOESS 

fits for streamgage 01634000, North Fork Shenandoah River 

at Strasburg, VA, showing typical problems (fig. 4). Actual 

ratings are carefully drawn (or fitted) through the highest 

measurements, those made when stage is controlled by a channel feature instead of a bed feature. Frequently, LOESS curves 

missed these points, and these points had large residuals. 

Although rating families could be separated using the residuals 

from these curves, these residuals were problematic for further 

statistical analysis. In contrast, the GAM curve fitted the high 

measurements neatly. 

In some cases, decreasing the span of the LOESS 

curve improved the fit of the high end, but this often came 

at the expense of causing the fit through the bulk of points 

to be eccentric or erratic. Residuals from these curves plotted against date were challenging to interpret because of the 

prevalence of artifacts. 

This pattern is general, not universal. A substantial 

number of the GAM curves have a worse fit through the data 

than one or several of the LOESS curves, even at the high 

end of the plot. A tally was made of which of the five types 

of smoothers used in the rating family plots had the best fit. 

Criteria for best fit include, in order of priority, splitting the 

difference cleanly when plots appeared to show multiple 

populations; handling changes in data density, particularly 

handling changes in the pattern of high measurements likely to 

represent the break onto the flood plain; insensitivity to small 

groups of outliers near a dense cloud of points; and smoothness of the curve.

The GAM curves have the best fit for 214 of the 331 sets 

of plots; this comparison included 30 rating families from 

partial-record and crest-stage sites that were ultimately not 

included in this report. In cases where the fit was not appreciably better for one type of curve than for another, the curve 

was counted with the family that less frequently had the best 

fit. For many of the sets of plots, several of the smoothers fitted well; for many of them, none fitted particularly well. The 

GAM curves seemed to excel at dealing with changes in data 

density. Often, the LOESS curves appeared to be affected by a 

dense cloud of data from a different range of values. Although 

no attempt was made to quantify which of the smoothers had 

the worst fit, the GAM plots generally had poor fits only if all 

the curves had poor fits. In contrast, LOESS curves with low 

span values (0.25 and 0.5) in some cases showed the best fit 

(40 and 20 times, respectively) but often fitted the data erratically and would have produced residuals that would have been 

difficult to interpret. 

Classification of Rating Families

Rating families were classified graphically in an iterative process. Plots were developed that included points of all 

the flow measurements that were stored in NWIS for each 

streamgage active in the real-time network as of November 

2013. Measurements with negative or zero flow values were 

removed from the dataset. Negative flows were clear indicators that streamgages did not have a simple relation between 

stage and flow. Observations of zero flow, similarly, could 

not be conclusively associated with their corresponding gage 

height in a meaningful way because, when the gage height of 

zero flow for a particular cross section is reached, stage could 

continue to drop. Once these measurements were removed 

from the local database, all streamgages with 20 or more measurements were retained for analysis. 

Curves were fitted through plots of gage height and 

flow. An initial series of plots was developed with a curve 

fit through all the points for each site, and a time series of 

residuals from these curves was plotted alongside the first plot 

(fig. 5; appendix 1). This process produced many artifacts and 

erratic patterns in the time series, but major changes could 

be identified. The gage height–flow plots were examined for 

clustering, but to lead to a classification as a rating family, a 

cluster had to correspond to a change in time that was evident 

in the time series plot. Types of changes in the time series 

plots used to classify rating families were, in order of priority, 

(1) abrupt steps upward or downward, (2) sloped transitions 

between flat steps, (3) major increases or decreases in variability, and (4) breaks in record greater than 2 years coinciding 

with differences, even ambiguous differences, in the appearance of plots. 

The major changes identified in the initial set of plots 

were discussed in the hydrographer interviews. Notes from 

these interviews, in combination with station records from the 

Site Information Management System (SIMS), field observations recorded on measurement forms, and in some cases, 

office records contemporaneous with the rating changes were 

used to explain the rating changes.

Once major changes had been identified and confirmed, 

measurements were designated as belonging to rating families. Both gage height and flow were log10 transformed. A new 

series of curves was fitted through the data, by major rating 
Patterns in the Stability of Stage-Flow Relations 19

6543210654321054321

Flow, in log units

-0.5-1.0

0

0.5

-0.2-0.4

0

0.40.2

-0.5-1.0

0

0.5

Residual of flow, in log units

-0.5-1.0

0

0.5

-0.2-0.4

0

0.40.2

-0.5-1.0

0

0.5

Residual of flow, in log units

-0.2 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

-0.2 0 0.2 0.4 0.6 0.8 1.0

0 0.2 0.4 0.6 0.8 1.0

1.2

1.2

1.4 1.6

0 100 200 300 400

0 100 200 300 400

0 100 200 300 400

Julian date

Date

RF2, R2 = 0.955

RF1, R2 = 0.9899

All measurements, R2 = 0.9700

All measurementsRF1RF2

All measurementsRF1RF2

Gage height, in log units

01/01/2000

01/01/2002

01/01/2004

01/01/2006

01/01/2008

01/01/2010

01/01/202

01/01/2014

01/01/1900

01/01/1920

01/01/1940

01/01/1960

01/01/1980

01/01/2000

01/01/2020

01/01/1900

01/01/1920

01/01/1940

01/01/1960

01/01/1980

01/01/2000

01/01/2020

EXPLANATION

A. Long-term stage-flow relations with a generalized additive model smoother

B. Residual of flow and date with a LOESS smoother

C. Residual of flow and Julian date with a LOESS smoother

Measurement date, 

by year

201320001975195019251907

Measurement date,

by month

DecemberSeptemberJuneMarchJanuary

Smoother—Shaded area represents 

99-percent confidence interval

(A and C) (B)

Figure 5. Streamgage 01668000, Rappahannock River near Fredericksburg, VA, showing: 

A, long-term stage-flow relations with a generalized additive model smoother, 

B, residual of flow and date with a LOESS smoother, and 

C, residual of flow and Julian date with a LOESS smoother. (R2, coefficient of determination)
20 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

family, and residuals again were captured and plotted as a time 

series. Rating family classifications were checked graphically, 

and further subdivisions became evident at this time. Rating 

family designations in the database were updated, and a set of 

plots was developed that displayed, by site, a complete time 

series of residuals from the rating family curves. Transitions 

between rating families were checked and where necessary 

corrected, but no new rating families were designated in this 

iteration. These plots are included in Appendix 1. 

Rating families were identified from the measurement 

plots. If clusters in the gage height flow plots could be related 

to major step trends or changes in variability in the residual 

time series, these sets of measurements were considered candidates for a rating family. Attempts were made to relate the 

events that changed the control to the observed differences in 

the plots. At the 174 sites, 301 rating families were identified 

(table 9, at end of report). At 107 sites, all measurements fit a 

single rating family. 

As an example of the classification process, the plots for 

01668000, Rappahannock River near Fredericksburg, VA, 

showed two rating families (fig. 5). Measurements from the 

establishment of the streamgage until 2000 generally clustered 

together on the plot of flow relative to gage height. The timeseries plots of residuals show occasional scatter and outliers 

but no obvious trend, whether stepped or gradual. In 2000, 

however, the relation between gage height and flow changed. 

Points on the gage height–flow plot that represent later measurements have a different slope than the previous points. This 

is seen in the residual of flow time series as greatly increased 

scatter beginning in 2000. Site records indicate that the 

streamgage was moved in October 2000. Measurements made 

before October 2000 are designated as belonging to Rating 

Family (RF) 1 and subsequent measurements as belonging 

to RF2. Curves are then fit separately to each rating family; 

residuals were captured from the curves and plotted as time 

series and by Julian date for each rating family. The new curve 

for RF2 fits those points better than the original curve fit all 

points. The coefficient of determination (R2) for RF1 is higher 

than that for the entire set of measurements (0.989 as compared to 0.9700); R2

 for RF2 is lower (0.9550). The time series 

indicates that since 2000, residuals have been negative or that 

less flow is associated with a given gage height. This may be 

the result of a long-term increase in deposition on the control 

or possibly some seasonal increase in macrophyte growth. If 

macrophyte growth were the likely cause, it might show up 

as large, negative residuals during summer and fall. This is 

in fact reflected in the time-series plot, although most of the 

recent winter measurements are lower than any measurements 

made before 2003. The plots of residuals and Julian date show 

little seasonal change for RF1, although variability was generally greater for the second half of the year. For RF2, overall 

variability is greater than for RF1, but the LOESS curve 

dips during summer when macrophyte growth is generally at 

its maximum.

At 67 sites, two or more rating families were identified. 

The maximum number of rating families was 7 at Chestnut 

Creek at Galax, for a total of 127 rating families that were 

delineated as separate. Of these 127 rating families, documented explanations were found for 67. The most common 

reasons for the control to change enough to represent a new 

rating family were moving the streamgage (28 times); floods 

(26 times); and construction activities, including bridge 

construction and removal, weir and control construction and 

removal, and channel or bed modifications (13 times). Sixteen 

of the rating families were classified at the end of a period of 

no data, including hiatuses in operation and periods when the 

streamgage was operated but measurements were not entered 

to the database. Forty-two rating families were identified from 

graphical appearance of the plots; eight of these had inconclusive or ambiguous documentation of stream channel changes.

Rating family changes related to floods represent a type 

of major change which real-time flow-data users might be 

able to anticipate. Of the 25 new rating families that were 

created by floods, most (18) were caused by major floods that 

changed ratings at more than one streamgage. The November 1985 flood caused by Hurricane Juan caused 9 of these 

changes, the June 1972 flood caused by Hurricane Agnes 

caused 3, and 2 each were caused by the August 1969 flood 

(Hurricane Camille), the January 1996 flood, and the September 1996 flood (Hurricane Fran). A major flood may cause a 

substantial rating change in any stream. Floods caused major 

rating changes in mountain streams with highly stable bedrock, or bedrock and boulder channels, although other nearby 

streams that also experienced major floods from the same 

storm showed small or no changes. Provisional flow data from 

any streamgage that has recently experienced a major flood, 

regardless of historical stability, is more uncertain than usual 

until post-flood evidence emerges that the rating remained 

stable or has again been well defined.

In many cases, clusters of several consecutive measurements temporarily departed from the time series; these were 

included for analysis but checked for explanations. Often, the 

departure was caused by human activities, such as a construction of a temporary dam used to facilitate bridge construction. Sometimes the departure was caused by beaver activity. 

Construction that subsequently affects the stage-flow relation 

at a streamgage typically will be reported to USGS in advance, 

and the information is likely to be made available to waterdata users. Beaver activity is difficult to anticipate but highly 

persistent. The presence of active beaver populations can be 

regarded as a characteristic of a site, as well as a strong predictor of degraded quality of flow records. 

Flow measurements made when the stream is at or near 

flood stage are typically included in rating analysis for years 

or decades, and ratings are carefully fitted through them. 

Although changes are sometimes observed in the high end 

of ratings and repeated flood measurements must be made 

whenever possible, the practice of including historical highflow measurements in ratings has been supported by repeated 

observations at many sites. Because these measurements are 

used to develop currently active ratings, the measurements are 

commonly included in NWIS, even if low-flow measurements 
Patterns in the Stability of Stage-Flow Relations 21

that were made during the same years have never been entered 

into the database. The high-flow measurements often show 

up as outliers on the time-series plots, however, because 

GAM curves developed for this study and fit to the full set of 

measurements sometimes miss these points and because these 

measurements are isolated in time. The high-flow measurements were included, even when they appeared to be outliers 

through an artifact of curve fitting, and represent one of the 

sources of error in the R2 of the GAM models.

Measurements made since the full implementation of 

NWIS in 1988 are intended to include information on whether 

or not the measurement was known to be in error and therefore 

excluded from the rating study during the year it was made. 

Common reasons for not being used include equipment failure 

or interference caused by flowing debris. Measurements made 

prior to the development of NWIS that were subsequently 

entered did not necessarily include this information. Measurements were screened as outliers both visually, from the plots, 

and by a check of divergence of four standard deviations from 

a running average of residuals in the time series. Greater effort 

was made to confirm visual outliers that indicated unusually 

high flow for a given gage height than was made for the opposite. Outliers indicating unusually high flow, when they result 

from accurate measurements, indicate temporary scour in 

the control. Temporary scour is less common than temporary 

backwater. When field or office notes indicated that outliers 

were considered to be unreliable measurements when they 

were made, they were excluded from analysis.

One of the limitations of the rating family classification 

is that, because classification was done graphically, it was subjective. Two alternate approaches were explored in an attempt 

to address this limitation. First, broken-stick regression and 

change-point analysis were explored but rejected as potential objective methods for classifying rating families. When 

applied to data from sites with clearly identified rating family 

changes that corresponded to well-documented causes, neither 

correctly identified the rating families. Second, the existing 

rating families were examined on an expanded scale. Rating families were further subdivided, and explanations were 

sought for the 108 new candidate rating families that were 

identified. Few of the new candidate rating families could be 

matched with explanatory events; only 1 of 108 candidates 

could be matched with remarks in the database or with measurement front sheets. Although base ratings were available 

for some of these candidate rating families, the base ratings 

generally changed at different times than this group of rating 

families. Because of the lack of corroborating evidence, this 

entire set of rating families was considered generally invalid 

and was abandoned. 

During iterations of the curve fitting, GAM curves 

that modeled gage height as a smoothing function of flow 

(GAMGH) and that modeled flow as a smoothing function 

of gage height (GAMQ) were developed and compared. 

The former curves follow the same convention as USGS 

streamgage ratings. Gage height is on the y-axis of a plot, 

and like actual stream rises and recessions, shows up as a 

vertical change. The latter curves, flow modeled as a function 

of gage height, seem superficially to mimic flow computation that might be done in a situation where gage height was 

known and flow is computed from an equation; however, for 

actual streamgages, flow is more commonly determined from 

gage height using database operations and matching a lookup 

table than computed from an equation. Both of these formats 

had advantages. When gage height is used on the y-axis as 

the dependent variable, stream filling and downcutting are 

portrayed in the same direction as they move in the physical 

world. When flow is used as the dependent variable, it facilitates comparison among sites for some purposes, although the 

relative importance of an arbitrary unit of flow is greater in a 

small creek than a large river.

The two sets of GAM models were compared graphically. For most sites, both models fit the available data 

equally well (215 of 301 rating families). The GAMGH models 

showed a better visual fit about twice as often as the GAMQ

models (56 and 23 rating families, respectively). For the other 

seven rating families, neither model was judged to fit well. 

Error terms for the two sets of GAM models, as well as 

Spearman’s rho correlation coefficients for gage height and 

flow within each rating family, were compared to the stability 

classes on the basis of expert judgement. Setting the classes 

Excellent, Good, Fair, and Poor equal to, 4, 3, 2, and 1, 

respectively, and performing correlation analysis resulted in 

Spearman’s rho correlation coefficients among rating families of 0.3790 for R2

 for GAMQ, -0.4687 for Spearman’s rho 

within each rating family, and 0.2982 for R2 for GAMGH. 

Boxplots of these two error terms showed slightly more 

separation among classes for the R2 of GAMQ than the other 

two terms (fig. 6). The better correlation among sites between 

stability classes for the R2 of GAMQ than for R2 of GAMGH

was contrary to the visual inspection of plots. Plots for those 

sites with a relatively high R2 for GAMQ and a relatively low 

R2 for GAMGH indicate that those sites predominantly had 

insensitive controls or controls where, at the low end of the 

rating, the change in flow was large relative to the change 

in stage. 

Owing to the iterative nature of the analysis in this study, 

several stability metrics that have not yet been discussed in 

this report were important to the final line of evidence used to 

select GAMQ over GAMGH as the preferred model for fitting 

measurements. The section “Relations Among Stability Metrics” farther on describes the manner in which the proposed 

metrics that were determined to be meaningful showed stronger correlations among sites with R2

 for GAMQ than among 

sites with R2 for GAMGH. 
22 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

EXPLANATION

75th percentile

25th percentile

Median

The largest value that does not exceed the 75th

percentile plus 1.5 times the interquartile range

The smallest value that is no less than the 25th

percentile minus 1.5 times the interquartile range

Outlier

0.2

0.4

0.6

0.8

1.0

1.2

R2 of GAM model of

gage height as a

function of flow

0.2

0.4

0.6

0.8

1.0

1.2

R2 of GAM model of

flow as a

function of gage height

Poor Fair Good Excellent

Descriptive stability class

Figure 6. Distribution of variability metrics for stage-flow relations, by descriptive stability class, for streamgages in Virginia 

active on September 30, 2013. (GAM, generalized additive model; R2, coefficient of determination)

Seasonal Changes to Stage-Flow Relations

Residuals from the fitted stage-flow curves, plotted by 

Julian date, show differences in rating stability throughout the 

year (appendix 1). Ratings can be grouped into three general 

classes. The first class, which is represented by 03173000, 

Walker Creek at Bane, VA, generally has been stable through 

time and at all times of the year (plate 1). At these sites, 

established ratings change rarely, if ever, and temporary shifts 

are also rare. At Walker Creek, the R2 of the GAMQ model is 

0.9966, and all available measurements fit a single rating family. A handful of low outliers, representing backwater conditions, have been observed. Most of these outliers were in the 

winter, and they were likely caused by ice. 

The second class, which is represented by 01631000, 

South Fork Shenandoah River at Front Royal, VA, is generally 

stable through time and consistent during winter and spring 

but usually shifts in the summer or fall. At these sites, the bed 

is typically stable, but seasonal plant growth or leaf accumulation on the control is routine. Although routine, the magnitude, duration, and timing of these shifts are different every 

year, and preliminary flow data at these sites might or might 

not need to be corrected. At South Fork Shenandoah River at 

Front Royal, all measurements fit a single rating family, the 

trend line for the long-term time series is generally flat, and 

R2 of GAMQ is 0.9694. There have been two periods when 

macrophyte or leaf shifts were unusually large, in the 1950s 

and since about 1988. Most of the low outliers were between 

Julian dates 200 and 300, or July through October. The control 

description (table 8) discusses shifting caused by aquatic 

growth and leaf fall; subsequent accumulation of leaves in 

streams rarely begins before September, so the largest shifts 

likely were caused by macrophyte growth.

The third class, which is represented by 01658500, South 

Fork Quantico Creek near Independent Hill, VA, especially 

RF1, is somewhat unstable at all times of the year. Rating 

instability at these sites is likely to be the result of a shifting, 

unstable bed. As at South Fork Quantico Creek, these sites are 

commonly subject to seasonal shifting as well. Although shifts 

are frequent at this site, they are not huge and scour is usually 

followed by fill. An exception was a flood in 1990 that caused 

a new rating family, but neither rating family had extreme 

variance; R2 was 0.9160 for RF1 and 0.9372 for RF2.

A banding pattern similar to that in the plot of residuals 

by Julian date for 02030500, Slate River near Arvonia, VA, is 

seen for some of the sites (plate 1). This pattern was investigated to determine whether it was an artifact of Julian date 

computation or was some other type of artifact. It was real. It 

shows up at sites operated by field offices that maintained the 

same field trip schedule consistently throughout the period of 

record. At these sites, measurements were consistently made 

the same weeks of each year. 

Long-Term Changes to Stage-Flow Relations

Patterns in rating residuals plotted as a time series show 

that ratings tend to reach equilibria of varying stability punctuated by disruptive events. Disruptive events, as demonstrated 

by the explanations for rating families (table 9), include major 

floods and human construction activities. The equilibria, 

generally, reflect conditions when a stable or relatively stable 

feature has formed or been built and that feature serves as 

the control. The time to equilibrium varies depending on the 

nature of the stream channel and the disruptive event. Disruptive events, such as weir construction, led to almost immediate 
Estimated Provisional Flows (AltFlows) 23

equilibria, but some floods caused changes that took extended 

periods to reach new equilibria.

Two examples of sites at which controls were changed by 

floods, but different amounts of time were needed to become 

stable, are 02021500, Maury River at Rockbridge Baths, VA, 

and 03207800, Levisa Fork at Big Rock, VA (plate 2). At the 

Maury River streamgage, where the channel is composed of 

bedrock and large boulders, the January 1996 flood altered the 

control so that flow at a given gage height increased. Because 

it increased throughout the range of stage, as shown by nearly 

all points that fall above the GAM curve on the stage-flow 

plot representing recent measurements, the control alteration 

might have been a large boulder moved downstream by the 

flood. Despite this change, all the measurements at this site 

were designated as belonging to a single rating family, with 

an R2 of 0.9935. At the Levisa Fork streamgage, where the 

control is cobble and boulder, the April 1978 flood destabilized the control. Prior to this flood, the control exhibited 

regular but relatively minor seasonal shifting. After the flood, 

variability increased, and the channel began to downcut. Following a major but undocumented change in 1988, variability 

decreased, but downcutting continued until about 2005. In 

1978, a flow measurement of 57.9 cubic feet per second (ft3/s) 

was made at a gage height of 4.12 ft; in 2013, a flow measurement of 61.1 ft3

/s was made at a gage height of 2.58 ft. The 

downcutting is further corroborated by hydrographer observations that water levels in the pool decreased enough that 

the stilling-well intakes were above the water and required 

modification. All of the downcutting cannot be attributed to 

channel response to the 1978 flood, as opposed to land use and 

other possible activities, but that flood clearly was a disruptive event that marked the beginning of a period of change for 

the control.

Two other types of long-term changes to controls 

are illustrated in plate 2. Scour-fill changes are shown for 

02065500, Cub Creek at Phenix, VA. At this streamgage, the 

control is sand and gravel, and it was affected by large woody 

debris. The earliest available data show that the stream was 

scouring the control until the late 1980s. It then filled over the 

next 10 to 12 years, while variability increased. In the early 

2000s, the stream began to scour again and has continued 

through 2013. 

At 02040000, Appomattox River at Mattoax, VA, the 

low-water control is thought to be a channel constriction, but 

shifting is caused by accumulation of sand and gravel in the 

streambed. Measurements have not been continuously available since the establishment of this streamgage. The earliest available data show little variation. The second block of 

available data, from the 1920s through the late 1950s, shows 

decreasing flow at a given gage height, which indicates channel aggradation, filling, or possibly, if the low-water control 

is in fact a channel constriction, increased constriction. Data 

are available beginning in 1988. During the period when data 

were unavailable, the channel downcut or widened. Since 

1988, however, the channel has been filling or constricting 

again, a pattern that increased about 2002. This site also exhibits seasonal shifting and, occasionally, a low measurement in 

the winter that might be affected by ice.

Estimated Provisional Flows (AltFlows)

Despite their limitations, provisional real-time flow data 

are indispensable for water managers. For some purposes, 

especially those related to flood warning and response, or 

for those for which precision is less important than relative 

change or timing, provisional data are likely to meet users’ 

needs. Provisional low flows, however, are likely to be revised 

before they become final for three reasons. (1) Low flows are 

sensitive to small changes in the control. (2) Low flows are 

common during summer and fall, and coincide with algae and 

macrophyte growth and leaf accumulation. (3) Low flows can 

be technically challenging to measure accurately, especially in 

rough stream channels, leading to more erratic ratings in such 

streams. Low stage is also technically challenging to measure in response to sediment deposition and where controls 

are insensitive. For users of provisional flows, especially low 

flows, quantifying differences between provisional and final 

flows would provide valuable insight into the reliability of 

provisional flows. 

A long-term comparison of provisional data against final 

data would provide a simple, direct measure of the changes 

that the data undergo through USGS processing and indicate 

the reliability of the provisional data for user decision making. Indeed, if provisional data were archived for the period 

of interest, a comparison between provisional and final data 

would be straightforward. However, provisional data are not 

archived. The USGS flow time-series database Automated 

Data Processing System (ADAPS) was developed in a time 

when data storage was much more expensive than it is now. 

Storing all preliminary and intermediate data was impractical 

until the late 1990s or early 2000s, and reworking the database 

to do so was not a high priority for data managers and software developers. For most sites, the storage of final, corrected 

unit values for gage height and flow began in the late 1990s 

or early 2000s. Paper tapes and data collection platform files 

were archived, but reconstructing a complete provisional time 

series from them would require several staff years of effort 

and was beyond the scope of this study. New software with a 

planned release date in 2017 is designed to include preservation of provisional data, as well as associated comments and 

computations that document and attribute each change in the 

data through time.

As a substitute for provisional flow data, an alternative series of daily flows (AltFlows; fig. 7) was developed 

(Messinger and Burgholzer, 2017). The primary steps were to 

acquire and compile ratings and daily flows for periods when 

ratings were available. Periods with complete records of shifts 

and ratings were identified. Daily flows were acquired for 
24 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

Determine station number

Determine date and time

Find rating number (RATNO) 

in effect

Find data descriptor (DD) 

in effect

Compile one-line commands

Retrieve individual 

expanded shifted ratings

Compile ratings into tables

Verify retrievals

Perform lookups

Compute AltFlows

START

END

Table of stations 

active as of 

September 30, 2013

Dates and times 

of flow measurements

Available from retrieval 

of base ratings

Available from retrieval 

of base ratings

Examine outliers and unexpected 

patterns in computed values

Do ratings need 

to be corrected?

Y

N

Figure 7. Major actions and data sources for computing alternative flow 

(AltFlow) tables for Virginia streams, water years 1991–2013.
Estimated Provisional Flows (AltFlows) 25

these periods. Expanded shifted ratings were acquired for days 

during these periods when flow measurements were made. 

Gage heights corresponding to mean daily flows were back 

calculated and identified as belonging to measurement-tomeasurement periods. These gage heights were then evaluated 

against two sets of ratings, those in effect when the measurement-to-measurement period began (Qsame) and those in effect 

when the previous measurement-to-measurement period began 

(Qprev). Qsame was used instead of the published daily values to 

avoid rounding errors. Daily mean flows were computed by 

averaging the unit values for each day but often failed to correspond to the flow increments in rating tables (fig. 7).

Several important sources of error in provisional flow 

data that are corrected in final flow data are missed by this 

process. Most important and common are errors that are 

not caused by changes to the control, and therefore are not 

corrected by changing ratings or shifts. These errors include 

ice-affected flows or missing records, which generally are 

estimated by hydrographic comparison to other streamgages. 

Errors in the stage record itself are relatively common for 

some sites, especially those with substantial sediment loads. 

These errors might be corrected or at least adjusted, or daily 

flows might be estimated for the period that was in error. 

Another difference between provisional and approved 

data not accounted for by this procedure is that expanded 

shifted ratings were selected as snapshots at the times when 

flow was measured, and the tens of thousands of other rating 

changes were ignored. Days when measurements were made 

have no particular relevance to the beginning or ending of 

shifts and rating changes. About one-third (7,346 of 23,126) 

of shift entries began on days when flow was measured, and 

of these, 2,679 were apparently procedural entries for shifts 

that were implemented in multiple steps throughout the day. 

Forty-one percent of unique shifts (6,842 of 16,853) began on 

days of peaks, either floods or high-flow pulses, and another 7 

percent (1,144 of 16,853) began the day after a peak; many of 

the shifts that began on days when measurements were made 

came on days of peaks and high-flow pulses. Prorating certain 

types of shifts through time is routine; the AltFlow procedure does not account for these changed shifts. As a result, 

the AltFlow time series is unlikely to have much relation to 

provisional data as they initially appeared on the web. It does, 

however, provide information on changes in the shifted rating 

from site visit to site visit and information on how the shifted 

rating changed throughout the range of observed flows.

AltFlow Development

AltFlow development involved inventory and assessment of ratings and shifts, acquisition of ratings and daily flow 

values, computation of Qsame and Qprev, and validation of these 

computations through a series of checks.

Rating Availability, Acquisition, and Compilation

Availability of ratings and shifts varied by streamgage 

(tables 3 and 4). Although daily flow values have been computed in NWIS since the adoption of the database, different 

centers and field offices archived different amounts of ancillary data, such as ratings and shifts, throughout the 1980s, 

1990s, and into the 2000s. Electronic archiving of all shifts 

and ratings did not become universal and mandatory until the 

2002 water year. Rating availability exceeded shift availability. All ratings and shifts were stored with their effective 

dates. Although a base rating may have been archived at a 

relatively late date, if it had been in effect previously, it was 

stored in association with its earliest available date. In some 

cases, the effective date preceded the development of NWIS. 

In these cases, however, there was no reason to go back and 

enter previous shifts, so they were never entered. However, 

there was no reasonable way to retrospectively tell the difference between cases when a base rating was entered after it had 

initially been developed and cases when a base rating without 

need for shifting was entered and used to compute flow values. 

Therefore, the beginning dates for potentially valid AltFlows 

data were set at the first date for each streamgage for which 

both a base rating and a shift were available. This procedure 

incorporates the assumption that all ratings and shifts that had 

been used were continuously available once they were initially 

available, which was impossible to check without site-by-site, 

year-by-year comparison of available data to printed station 

analyses. However, on review of a summary of the number of 

base ratings and shifts available by year (tables 3 and 4), the 

assumption seemed plausible.

As discussed previously, preferred approaches to dealing 

with rating changes may vary by analyst and field office. It 

was, however, straightforward to avoid arbitrary differences 

between ratings and shifts by using expanded shifted rating 

tables, the final rating tables used in the database to compute flow. As discussed previously, ratings and shifts change 

frequently, sometimes abruptly and sometimes gradually; they 

may be implemented at once, prorated over a few hours during 

a rise or recession, or prorated over several weeks when weeds 

are thought to have been growing or leaves are thought to have 

been accumulating. To make the task at hand less impractical, expanded shifted ratings were retrieved only for the times 

when flow measurements were made. 

Retrievals of shifted ratings were made for the precise date and time of the measurement. On days when stage 

changes, the measurement checks only the segment of the 

rating near that same range of stage; stated another way, an 

instantaneous flow measurement provides a reliable check for 

a published daily value for a day when flow did not change. 

Accounting for measurement timing on the retrieval was 

particularly important because extra effort was made to catch 
26 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

high measurements, nearly all of which were made on days 

when flow changed. 

Archived expanded shifted ratings were not readily available to the public, and retrievals required direct access to the 

command line of the Virginia Water Science Center NWIS 

server. The ratings that originally were not readily available 

to the public have been published (Messinger and Burgholzer, 

2017). The tools and actions used to compute AltFlows are 

described in appendixes 2 and 3. 

Special Conditions Affecting Some AltFlows

During the process of validating the AltFlow data, several 

extreme values were identified and investigated to determine 

whether they reflected (1) artifacts of the AltFlow development process, (2) special conditions related to the flow data 

collection and processing, or (3) exceptionally unstable 

controls. The extreme values that were identified as artifacts of 

the AltFlow development process were corrected. All the artifacts that were identified resulted from errors in the expanded 

shifted rating retrieval that in turn resulted from complications 

in the manner in which ratings were coded and stored. Special 

conditions related to flow data collection and processing that 

affected some AltFlows are discussed below. Other special 

conditions that resulted in modest rather than dramatic effects 

to AltFlows may have gone unnoticed. 

Streamgage Datum Changes

On occasion, generally in response to scour at the 

streamgage control, the datum of the streamgage is changed. 

Often the change is made in order to avoid a zero or negative 

gage height, which would be undefined on log-scale plots; 

datum changes are always or nearly always positive because 

there is no practical reason to make a negative datum change. 

Datum changes are typically made in increments of one or 

more feet. Large datum changes (3 feet or more) would typically be made if continued scour was anticipated. Because the 

datum is arbitrary in the first place, these datum changes are 

made for the convenience of the hydrographers. The datum 

change itself is inconvenient, so datums are changed rarely.

Datum changes were made six times at streamgages for 

which valid AltFlows could have been computed (table 10). 

The sets of ratings for these six sites were adjusted for datum 

corrections. They are the only sites in the study to which a 

datum correction was applied during a period when valid 

AltFlows could have been computed. For each of the sites in 

table 10, the appropriate number of rows (200 for the three 

sites with 2.00-foot datum corrections, 300 for the sites with 

the 3.00-foot datum correction, and 3,099 for the sites with 

the 30.99-foot datum correction) was inserted into the columns representing expanded shifted ratings for all dates prior 

to the datum correction. All stage measurements in the rating 

tables now represent the same datum for each site. No manual 

change had to be made for the flow table; once the ratings 

were adjusted, the lookup functions were able to find the corrected gage heights without any further modification.

Moving a Streamgage

Sometimes it is necessary to move a streamgage. Reasons 

include, but are not limited to, stream channel migration away 

from the streamgage location, frequent deposition of sediment on the intake or orifice, demolition of a bridge or other 

structure to which the streamgage is attached, construction 

of a bridge or other structure that interferes with streamgage 

operation, structural damage to a gaging structure, and determination that a control is unstable and better record could be 

obtained elsewhere on the same stream.

Streamgages are sometimes moved from one location 

to another within the same gaging pool. Under these circumstances, when the new streamgage location uses the same 

control, little if any change to the rating is to be expected. 

Otherwise, changes to the rating after the move are unsurprising, and comparing ratings from before and after the move 

provides no information on rating stability. Not only that, 

but when a streamgage is moved somewhere with a different 

control, standard procedure is to stop publishing preliminary 

flow data to the web until the new rating has been established, 

which generally takes several months. 

Three streamgages were moved to new gaging pools 

during water years 2013 (table 11). Two of these moves, for 

Table 10. Locations, magnitudes, and dates of datum changes for 

streamgages in Virginia, water years 1990–2013.

[VA, Virginia]

Streamgage 

number Streamgage name

Magnitude of 

datum change, 

in feet

Date of 

datum 

change

02011460 Back Creek near Sunrise, VA 2.00 10/28/2008

02027000 Tye River near Lovingston, VA 2.00 9/3/2004

02027500 Piney River at Piney River, VA 3.00 11/3/2009

02061500 Big Otter River near Evington, VA 2.00 6/9/2005

02077000 Banister River at Halifax, VA 3.00 9/24/2002

02047500 Blackwater River near Dendron, VA 30.99 11/28/2012
Estimated Provisional Flows (AltFlows) 27

01615000, Opequon Creek near Berryville, and 01662800, 

Battle Run near Laurel Mills, coincided with discontinuation of the streamgage. The third, 01668000, Rappahannock 

River near Fredericksburg, was moved to a new gaging pool 

in March 2001 owing to safety and access concerns. Values 

of Qsame were deleted for the period between the streamgage 

move and the next flow measurement, and values of Qprev were 

deleted until the subsequent flow measurement. 

Suspension of Streamgage Operations

When streamgages are discontinued but later reactivated, 

the old rating remains in the database and might be used as a 

temporary rating to generate provisional data while measurements are being made either to verify it or to generate a new 

rating. These provisional data would not ordinarily be published to the web before the rating was verified, so a comparison between the old rating and the updated rating would 

ordinarily not be useful.

Eighteen streamgages were discontinued for 30 days 

or longer, but were later reactivated, during water years 

1991–2013 (table 12). For eight of these streamgages, the 

hiatus came before the earliest valid AltFlow date (varying 

by site; the earliest date at which two flow measurements 

had been made after shifts and ratings began to be stored in 

the database).

For the 10 streamgages for which the hiatus came during 

a period with potentially valid AltFlows, the AltFlow daily 

values were not computed using the pre-hiatus rating. Qprev

values were resumed once two flow measurements had been 

made following the hiatus.

Estimated and Qualified Daily Flows

As discussed previously, at times when stage record is 

missing or in error, daily values are estimated. Errors in stage 

record may be caused by instrument failure, sediment deposition on the intake or orifice, or ice effect. Estimates may be 

based on partial record at the streamgage being estimated or 

on hydrographic comparison with nearby streamgages known 

to be correlated with the streamgage being estimated. Weather 

records are checked for rain or freezing temperatures. 

A critical issue for purposes of this study is that 

daily flow values may be estimated without any use of the 

streamgage’s rating. Nearly as important, if flow is to be estimated for a small amount of record and limited to part of the 

hydrograph where a shift might be needed if flow were to be 

computed, the need for a shift is moot. These factors represent 

limitations of the AltFlow approach, and AltFlows have little 

relevance for periods of estimated records.

The total percentage of estimated days at a streamgage 

may be a reasonable surrogate for quality of the stage record. 

For days when AltFlow record was developed, 4 percent of the 

overall record combined from all streamgages was estimated. 

Ten percent or more of the overall record was estimated for 

seven sites (01643805, North Fork Goose Creek at Route 729 

near Lincoln; 02032250, Moormans River near Free Union; 

02079640, Allen Creek near Boydton; 01660400, Aquia Creek 

near Garrisonville; 01616100, Dry Marsh Run near Berryville; 

01654000, Accotink Creek near Annandale; and 02040000, 

Appomattox River at Mattoax; table 13, at end of report). 

The number of estimated days during the winter may be 

a fair surrogate for the amount of ice effect at a streamgage, 

in particular for streams where little record is estimated during other seasons (table 13). For the entire network during 

water years 1991–2013, 7 percent of the overall winter record 

(December, January, and February) was estimated. January 

was the month with the greatest rate of estimated record, and 

28 percent of the overall estimated days were during January. 

At 5 streamgages, 20 percent or more of winter record was 

estimated; 10 percent or more of winter record was estimated 

at 54 streamgages. Most streamgages with a high rate of 

estimated record during the winter were at high elevations or 

had small drainage areas. At 26 streamgages, 1 percent or less 

of winter record was estimated; at 14 of those, 0 percent of 

winter record was estimated. Most of these streamgages were 

on large rivers, directly downstream from dams, or had a short 

period of record.

At one site (02077000, Banister River at Halifax, VA) 

daily flows were estimated on 230 days from 1999 through 

2002 because valid stage measurements were not available. 

Estimates were based on hydrographic comparison with 

other streamgages. This happened on days when the gage 

height was missing because stage was low enough that the 

stilling-well intake was out of the water. These days also 

lack a value for Qprev, even though apparently valid previous 

ratings exist. Because the original stage record was missing, 

Table 11. Streamgages that were moved to new gaging pools, and dates 

of the move, in Virginia, water years 1991–2013.

[Gages that were moved to new locations in the same gaging pool with the same control 

are not included; VA, Virginia]

Streamgage 

number Streamgage name Date the gage was moved

01615000 Opequon Creek near Berryville, VA 10/15/2002

01662800 Battle Run near Laurel Mills, VA 10/3/1997

01668000 Rappahannock River near Fredericksburg, VA 3/6/2001
28 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

Table 12. Virginia streamgages that were discontinued and reactivated for 30 or more consecutive days, and the dates they were 

discontinued and reactivated, water years 1991–2013.

[AltFlow, alternative flow tables; VA, Virginia]

Streamgage 

number Streamgage name Date discontinued

Date 

reactivated Date AltFlow resumed

01615000 Opequon Creek near Berryville, VA 10/19/1997 10/1/2002 12/10/2002

01626850 South River near Dooms, VA 12/10/1996 7/21/2005 10/14/2005

01643700 Goose Creek near Middleburg, VA 1/28/1997 6/28/2001 No lost AltFlow record; 

no valid AltFlows from before hiatus

01660400 Aquia Creek near Garrisonville, VA 10/15/1997 11/4/1999 No lost AltFlow record; 

no valid AltFlows from before hiatus

01662800 Battle Run near Laurel Mills, VA 7/10/1995 10/1/1997 10/30/1997

01663500 Hazel River at Rixeyville, VA 10/12/1992 10/1/2001 No lost AltFlow record; 

no valid AltFlows from before hiatus

01665500 Rapidan River near Ruckersville, VA 6/30/1995 10/1/1998 No lost AltFlow record; 

no valid AltFlows from before hiatus

01670400 North Anna River near Partlow, VA 9/30/1995 3/27/2007 5/1/2007

01671100 Little River near Doswell, VA 9/30/1999 9/22/2000 No lost AltFlow record; 

no valid AltFlows from before hiatus

01672500 South Anna River near Ashland, VA 9/30/1997 6/28/2003 7/17/2003

02020500 Calfpasture River above Mill Creek at Goshen, VA 9/30/1996 10/1/1998 No lost AltFlow record; 

no valid AltFlows from before hiatus

02030000 Hardware River below Briery Run near Scottsville, VA 10/10/1995 10/1/1996 No lost AltFlow record; 

no valid AltFlows from before hiatus

02030500 Slate River near Arvonia, VA 10/15/1995 6/23/2005 8/2/2005

02032250 Moormans River near Free Union, VA 9/30/1997 7/7/2005 No lost AltFlow record; 

no valid AltFlows from before hiatus

02077000 Banister River at Halifax, VA 11/10/2011 3/1/2012 3/25/2012

02079640 Allen Creek near Boydton, VA 10/20/1996 10/1/2000 11/29/2000

03175500 Wolf Creek near Narrows, VA 9/30/1995 10/1/1996 11/12/1996

03177710 Bluestone River at Falls Mills, VA 4/27/1997 9/22/2004 12/8/2004
Estimated Provisional Flows (AltFlows) 29

the hydrographer had no practical reason to develop a rating 

for that range of stage, and therefore there was no defined gage 

height that corresponded to the daily flows for those days. This 

ended in September 2002, when the stilling well was replaced 

with a bubbler system that could measure lower stage values, 

and the datum was changed.

Retrievals of daily flow values include, by default, a 

column of qualifiers. The qualifier for estimated flows (A:e) 

is one of these. Two other qualifiers were common. The first 

and by far the most common is A, for approved, indicating 

that flows were computed in the usual way. The second is A:1, 

which is described in comment fields as indicating that daily 

flow values are write-protected without any remark code to be 

printed. What this typically means in practice is that for some 

reason, the stage recorder collected a partial day of record 

while flow was stable, and the mean daily flow computed 

from available values was judged to characterize the day. 

Unit values would have been recorded under a different data 

descriptor (DD), and particularly early in the 1990s, they may 

have been processed under that DD and entered manually into 

the daily flow table. In such cases, these values might potentially have been developed from a different rating than the one 

used for the development of AltFlows. These values represent less than one-half a percent of the total record for which 

AltFlows were developed.

Days of Zero Flow

An observation of zero flow can be associated with more 

than one gage height; once flow decreases to zero, the stage of 

the gaging pool can continue to decrease as flow remains zero. 

On days when AltFlows were calculated, Qmeas was observed a 

total of 2,620 days at 26 streamgages (table 14). At four sites, 

zero flow was observed 100 or more times, with a maximum 

Table 14. Number of days with zero flow for streamgages in Virginia, water 

years 1991–2013.

[VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name Days of zero flow

01638350 South Fork Catoctin Creek at Rt 698 near Waterford, VA 28

01638420 North Fork Catoctin Creek at Rt 681 near Waterford, VA 110

01643700 Goose Creek near Middleburg, VA 52

01643880 Beaverdam Creek at Rt 734 near Mountville, VA 196

01645704 Difficult Run above Fox Lake near Fairfax, VA 6

01654000 Accotink Creek near Annandale, VA 14

01656000 Cedar Run near Catlett, VA 4

01658500 South Fork Quantico Creek near Independent Hill, VA 51

01660400 Aquia Creek near Garrisonville, VA 1

01662800 Battle Run near Laurel Mills, VA 1

01669000 Piscataway Creek near Tappahannock, VA 24

01669520 Dragon Swamp at Mascot, VA 56

01673550 Totopotomoy Creek near Studley, VA 35

01673800 Po River near Spotsylvania, VA 8

01674000 Mattaponi River near Bowling Green, VA 72

02030000 Hardware River below Briery Run near Scottsville, VA 1

02031000 Mechums River near White Hall, VA 26

02032250 Moormans River near Free Union, VA 5

02037000 James River And Kanawha Canal near Richmond, VA 775

02041000 Deep Creek near Mannboro, VA 4

02046000 Stony Creek near Dinwiddie, VA 3

02047500 Blackwater River near Dendron, VA 972

02049500 Blackwater River near Franklin, VA 12

02051000 North Meherrin River near Lunenburg, VA 5

02065500 Cub Creek at Phenix, VA 1

02079640 Allen Creek near Boydton, VA 158

Total 2,620
30 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

of 972 days of zero flow at 02047500, Blackwater River 

near Dendron. 

Because an observation of zero flow is of particular concern to water managers interested in knowing the reliability of 

provisional flow during low-flow periods, these observations 

were all retained, and Qsame and Qprev were computed for them, 

despite some ambiguity in back calculating their gage heights.

Qsame and Qprev were not always zero on the same dates. 

Values of zero flow for Qsame were computed on 697 days when 

Qprev had flows at 13 sites (table 15). At these sites, mean values of Qprev ranged from 0.01 ft3

/s to 136 ft3/s. Values of zero 

flow for Qprev were computed on 1,023 days when Qsame had 

flows at 19 sites (table 16). At these sites, mean values of Qprev

ranged from 0.01 ft3/s to 87.6 ft3/s. For both of these characteristics, the same site (02037000, James River and Kanawha 

Canal near Richmond, VA) had the maximum value when a 

zero value was observed for the other characteristic.

Previously Undefined Ratings

One of the circumstances for which Qprev could not be 

computed when a valid previous rating was available was 

when stage entered a range where it was undefined in the 

previous rating. This happened for two different reasons, 

either (1) scour to the control, which resulted in ordinary 

flows becoming associated with unprecedented low stage, 

or (2) flows were higher or lower than had previously 

been measured. 

One fairly common scenario concerning undefined 

ratings was where the control scoured to an elevation lower 

than previously defined in the rating. When this happens, the 

streamgage’s real-time page displays a clearly labeled red line 

showing the minimum plausible limit of the rating as designated by the field office. Preliminary flow data lower than this 

threshold are not published to the web, and an explanation is 

provided on the real-time page. In this retrospective analysis, 

however, these scour events resulted in periods during which a 

valid previous rating had been in effect but Qprev was missing. 

While not necessarily more problematic than any other 

undefined ratings for real-time flow data users, ratings for 

which zero flow was undefined were a complication for 

computing Qprev. If the previous rating included a gage height 

at which flow was zero, flow remained zero for all lower 

gage heights, so that strictly speaking, the value of these gage 

heights was defined. If the minimum defined flow was greater 

than zero, then Qprev represented a non-detect. The lowest 

defined flow represented a detection limit, and flows lower 

than that were known only to be lower than the detection limit. 

Water-quality analysts frequently work with concentration 

data that represent quantification at less than a detection limit 

and do so using a variety of approaches, all of which have 

some advantages but none of which is completely satisfactory for all purposes (Helsel and Hirsch, 2002). For purposes 

of this analysis, the Qprev values that were less than a nonzero 

threshold were arbitrarily set equal to the minimum flow value 

defined in the relevant rating—the detection limit—because 

VDEQ water managers determined the most likely guidance 

that they would give holders of withdrawal permits who asked 

about missing values in this circumstance would be to assume 

flow was equal to the last posted value until new flow values 

Table 15. Number of days when Qsame equaled zero but Qprev did not, and mean and maximum values of Qprev for those days for 

streamgages in Virginia, water years 1991–2013.

[Qprev, the flow value from the shifted rating table in effect at the time of the previous flow measurement that corresponds to the gage height of each day’s 

daily flow value; Qsame, the flow value from the shifted rating table used to compute the daily flow value at the time of the most recent flow measurement that 

corresponds to the gage height of each day’s daily flow value; ft3/s, cubic feet per second; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name

Number of days 

when Qsame = 0, 

but Qprev did not

Mean of Qprev

on those days 

(ft3/s)

Maximum of Qprev

on those days 

(ft3/s)

01638420 North Fork Catoctin Creek at Rt 681 near Waterford, VA 69 0.04 0.21

01643700 Goose Creek near Middleburg, VA 52 3.90 3.90

01643880 Beaverdam Creek at Rt 734 near Mountville, VA 63 16.9 19.0

01654000 Accotink Creek near Annandale, VA 2 0.01 0.01

01656000 Cedar Run near Catlett, VA 7 0.05 0.05

01658500 South Fork Quantico Creek near Independent Hill, VA 17 0.16 0.27

01660400 Aquia Creek near Garrisonville, VA 2 0.14 0.14

01669000 Piscataway Creek near Tappahannock, VA 24 2.50 2.50

01669520 Dragon Swamp at Mascot, VA 11 0.64 0.64

02037000 James River And Kanawha Canal near Richmond, VA 291 136 643

02047500 Blackwater River near Dendron, VA 143 0.36 0.83

02051000 North Meherrin River near Lunenburg, VA 3 0.08 0.08

02079640 Allen Creek near Boydton, VA 13 2.48 9.50
Estimated Provisional Flows (AltFlows) 31

Table 16. Number of days when Qprev equaled zero but Qsame did not, with mean and maximum values of Qprev for those days for 

streamgages in Virginia, water years 1991–2013.

[Qprev, the flow value from the shifted rating table in effect at the time of the previous flow measurement that corresponds to the gage height of each day’s daily 

flow value; Qsame, the flow value from the shifted rating table used to compute the daily flow value at the time of the most recent flow measurement that corresponds to the gage height of each day’s daily flow value; =, equals; ft3

/s, cubic feet per second; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name

Number of days 

when Qsame = 0, 

but Qprev did not

Mean of Qprev

on those days 

(ft3/s)

Maximum of Qprev

on those days 

(ft3/s)

01620500 North River near Stokesville, VA 43 16.3 43.0

01632900 Smith Creek near New Market, VA 37 16.4 38.0

01638420 North Fork Catoctin Creek at Rt 681 near Waterford, VA 5 0.38 0.58

01643880 Beaverdam Creek at Rt 734 near Mountville, VA 87 0.98 2.70

01645704 Difficult Run above Fox Lake near Fairfax, VA 7 0.44 0.50

01654000 Accotink Creek near Annandale, VA 16 3.79 6.70

01658500 South Fork Quantico Creek near Independent Hill, VA 135 2.10 5.30

01669000 Piscataway Creek near Tappahannock, VA 4 0.56 0.64

01673800 Po River near Spotsylvania, VA 19 0.03 0.08

01674000 Mattaponi River near Bowling Green, VA 231 13.8 55.0

02030000 Hardware River below Briery Run near Scottsville, VA 8 0.01 0.01

02032250 Moormans River near Free Union, VA 6 0.02 0.02

02036500 Fine Creek at Fine Creek Mills, VA 12 0.13 0.49

02037000 James River And Kanawha Canal near Richmond, VA 90 87.6 114

02038850 Holiday Creek near Andersonville, VA 6 0.04 0.06

02046000 Stony Creek near Dinwiddie, VA 44 1.72 4.9

02047500 Blackwater River near Dendron, VA 45 29.2 73.0

02051000 North Meherrin River near Lunenburg, VA 6 0.11 0.15

02079640 Allen Creek near Boydton, VA 222 3.38 28.0

appear on the web (Scott Kudlas, Virginia Department of 

Environmental Quality, oral commun., October 2015). During water years 1991–2013, there were 1,330 days of record 

with undefined Qprev values but with a valid previous rating; 

these occurred for 57 sites and include 220 discrete incidents 

(table 17). 

A different scenario of an undefined range of a valid 

previous rating that also resulted in a missing Qprev was when 

flows were first measured that were either higher or lower 

than any previous flow. Flows higher than the maximum flow 

defined in previous ratings were rare and affected only 6 days 

of AltFlow records. One day each at three sites (01644280, 

Broad Run near Leesburg; 02040892, Appomattox River at 

Route 602 near Mannboro; and 02049500, Blackwater River 

near Franklin) and 3 days at another site (02047500, Blackwater River near Dendron, estimated values in a flood during 

September 1999) were adjusted to account for flows higher 

than previously encountered. New low flows of record were 

more common during the study period and affected more 

AltFlow record. When flows reached new lows, they typically remained low for several days. Undefined ratings caused 

by scour represent an important type of instability, whereas 

undefined ratings caused by higher or lower flows than had 

previously been encountered are (1) less likely to recur and (2) 

don’t represent instability at all, just the first time a particular 

set of hydrologic conditions were recorded at a streamgage. 

There were 37 days of record at 15 sites with undefined ratings, on which flows were lower than they had been since 

October 1, 1990, the beginning of the study period (table 17). 

These seem likely to represent cases when the rating was 

undefined because flows reached new lows, rather than 

because the control scoured. 

A different scenario involving undefined ratings is that, 

for a few sites, approved daily values were less than the 

minimum flow defined in the expanded shifted rating presumably used to compute the flow value (table 18). This happened 

on 249 days at nine sites. Nine of these 249 values were 

estimated, so these values may have been computed through 

hydrographic comparison. The other 240 values possibly were 

computed using stage measurements from a backup recorder 

outside the default DD for flow using a rating for that DD, 

then written as unit flow values. In any case, the 240 values do 

not correspond to any rating available for analysis, and their 

presence resulted in an error in Microsoft Excel. For all 249, 

Qprev and Qsame were deleted from their respective rows, and 

comments were added explaining the deletion.
32 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

Table 17. Number of times ratings entered ranges that had been undefined in the previous actual rating and set equal to the 

defined rating minimum for the purpose of this analysis, and number of days they were in such ranges for streamgages in Virginia, 

water years 1991–2013.—Continued

[AltFlow, alternative flow tables; Qprev, the flow value from the shifted rating table in effect at the time of the previous flow measurement that corresponds to 

the gage height of each day’s daily flow value; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name

Days of AltFlow 

record based 

on previously 

undefined ratings

Number of discrete 

incidents when 

Qprev could not be 

computed because 

the previous rating 

was undefined

Number of days 

with undefined 

previous ratings that 

were new record 

low flows since 

October 1, 1990

01613900 Hogue Creek near Hayfield, VA 18 2

01615000 Opequon Creek near Berryville, VA 5 5 2

01621050 Muddy Creek at Mount Clinton, VA 117 10

01626850 South River near Dooms, VA 67 7

01628500 South Fork Shenandoah River near Lynnwood, VA 6 1 3

01632000 North Fork Shenandoah River at Cootes Store, VA 21 5

01643700 Goose Creek near Middleburg, VA 2 1

01643805 North Fork Goose Creek at Rt 729 near Lincoln, VA 24 4

01643880 Beaverdam Creek at Rt 734 near Mountville, VA 25 3

01644280 Broad Run near Leesburg, VA 1 1

01645762 South Fork Little Difficult Run above Mouth near Vienna, VA 9 2

01646305 Dead Run at Whann Avenue near Mclean, VA 1 1

01652500 Fourmile Run at Alexandria, VA 3 3

01653000 Cameron Run at Alexandria, VA 93 27 3

01656903 Flatlick Branch above Frog Branch at Chantilly, VA 36 10

01658500 South Fork Quantico Creek near Independent Hill, VA 70 9

01660400 Aquia Creek near Garrisonville, VA 22 1

01662800 Battle Run near Laurel Mills, VA 43 5

01663500 Hazel River at Rixeyville, VA 4 2

01664000 Rappahannock River at Remington, VA 29 4

01666500 Robinson River near Locust Dale, VA 42 5 3

01667500 Rapidan River near Culpeper, VA 1 1 1

01668000 Rappahannock River near Fredericksburg, VA 13 1

01671025 North Anna River above Little River near Doswell, VA 9 9

01673550 Totopotomoy Creek near Studley, VA 16 2

01673800 Po River near Spotsylvania, VA 38 7

01674000 Mattaponi River near Bowling Green, VA 82 9 5

01674500 Mattaponi River near Beulahville, VA 11 2 8

02011460 Back Creek near Sunrise, VA 2 1

02013000 Dunlap Creek near Covington, VA 42 3

02014000 Potts Creek near Covington, VA 10 2

02022500 Kerrs Creek near Lexington, VA 58 4

02024915 Pedlar River at Forest Road near Buena Vista, VA 11 3 1

02032250 Moormans River near Free Union, VA 1 1 1

02032640 North Fork Rivanna River near Earlysville, VA 7 1

02040892 Appomattox River at Route 602 near Mannboro, VA 1 1

02041000 Deep Creek near Mannboro, VA 1 1

02041650 Appomattox River at Matoaca, VA 7 1 0

02042500 Chickahominy River near Providence Forge, VA 26 9 0

02045500 Nottoway River near Stony Creek, VA 10 2 3
Estimated Provisional Flows (AltFlows) 33

Table 17. Number of times ratings entered ranges that had been undefined in the previous actual rating and set equal to the 

defined rating minimum for the purpose of this analysis, and number of days they were in such ranges for streamgages in Virginia, 

water years 1991–2013.—Continued

[AltFlow, alternative flow tables; Qprev, the flow value from the shifted rating table in effect at the time of the previous flow measurement that corresponds to 

the gage height of each day’s daily flow value; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name

Days of AltFlow 

record based 

on previously 

undefined ratings

Number of discrete 

incidents when 

Qprev could not be 

computed because 

the previous rating 

was undefined

Number of days 

with undefined 

previous ratings that 

were new record 

low flows since 

October 1, 1990

02046000 Stony Creek near Dinwiddie, VA 31 7 0

02047500 Blackwater River near Dendron, VA 41 4 0

02052000 Meherrin River at Emporia, VA 18 1 0

02061000 Big Otter River near Bedford, VA 10 1 1

02062500 Roanoke (Staunton) River at Brookneal, VA 69 3 0

02077000 Banister River at Halifax, VA 9 8 0

02077500 Hyco River near Denniston, VA 2 1 2

02079640 Allen Creek near Boydton, VA 1 1 0

03170000 Little River at Graysontown, VA 10 1 0

03173000 Walker Creek at Bane, VA 2 1 0

03176500 New River at Glen Lyn, VA 1 1 0

03177710 Bluestone River at Falls Mills, VA 7 2 2

03207800 Levisa Fork at Big Rock, VA 1 1 0

03208950 Cranes Nest River near Clintwood, VA 45 6 0

03473000 South Fork Holston River near Damascus, VA 27 7 1

03478400 Beaver Creek at Bristol, VA 66 6 1

03531500 Powell River near Jonesville, VA 6 1 0

Total 1,330 220 37

Table 18. Days of approved flow record less than their respective rating minima for streamgages 

in Virginia, water years 1991–2013.

[VA, Virginia]

Streamgage 

number Streamgage name Dayscomputed

Days

estimated

Total 

days

02031000 Mechums River near White Hall, VA 52 6 58

02041000 Deep Creek near Mannboro, VA 1 0 1

02041650 Appomattox River at Matoaca, VA 4 0 4

02042500 Chickahominy River near Providence Forge, VA 18 0 18

02047000 Nottoway River near Sebrell, VA 0 3 3

02047500 Blackwater River near Dendron, VA 156 0 156

01643700 Goose Creek near Middleburg, VA 5 0 5

01656000 Cedar Run near Catlett, VA 1 0 1

03473000 South Fork Holston River near Damascus, VA 3 0 3

Total 240 9 249
34 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

Unusual Sites

 At streamgage 02037000, James River and Kanawha 

Canal near Richmond, VA, flow is challenging to measure 

using ordinary methods. The accuracy of flow records from 

the canal is questionable, especially low-flow records. It has 

a low gradient and extreme rating changes. The manuscript 

in Annual Water-Data Reports and Water-Year Summaries 

for this site includes the qualifying statement “Canal diverts 

from James River 1,200 ft upstream from Bosher Dam and 

discharges into river at several points downstream from gaging 

station near Richmond. Beginning with the 1969 water year, 

the descriptive statement that above 2,540 ft3/s, gage height, 

14.5 ft, there is interchange of flow with the James River and 

that discharge above 2,540 ft3/s is included in discharge for the 

James River near Richmond (streamgage 02037500) has been 

used. Daily discharges in excess of 2,540 ft3/s for water years 

1937–68 should be used with caution until historical records 

of canal construction and modifications can be reviewed. 

Figures given show flow in canal only” (U.S. Geological 

Survey, 2017).

The site 02047500, Blackwater River at Dendron, VA, 

is a problematic site. It is affected by variable backwater, and 

hydrographers described this site as subject to frequent beaver 

activity. Issues were exhibited through all the lines of evidence 

examined in this study. Measurements plotted far to the left of 

their ratings at irregular but recurrent intervals, indicating the 

effect of some type of backwater. These backwater-affected 

measurements generally lined up with each other as a second 

ghost line on the long-term rating plot. Ratings also shifted by 

several feet from time to time, resulting in AltFlows computed 

from previous ratings that were undefined on the low end one 

time and on the high end the next. The ratings and measurements for this site were reviewed for some sort of processing 

artifact during the course of this study; the review found that 

the ratings and measurements accurately reflected the values 

stored in NWIS. 

The site 01671025, North Anna River above Little River 

near Doswell, VA, is a continuous partial-record site. At this 

site, flow is not computed when stage is above 12.0 feet. This 

results in many short gaps in the flow record and limits the 

number of flow statistics that can be computed from this site’s 

record. Although this site was included in most analyses in this 

study, the partial nature of its record prevented it from being 

included in others.

Comparison of Ratings and Measurements as a 

Check on Rating Compilation

Comparing flow measurements to expanded shifted 

ratings retrieved for the time of the measurement shows how 

often hydrographers develop ratings within the stated guidelines (Rantz and others, 1982). For a measurement rated Good 

by the hydrographer, a shift or rating is to be developed within 

5 percent of the measurement. For a measurement rated Fair, 

the rating is to be within 8 percent, and only if a measurement 

is rated Poor is the rating to be left with a greater than 8 percent difference. Hydrographers may also decide in the field or 

the office that a measurement was faulty; such a measurement 

may be disregarded (not used in working the record) or, in 

a less extreme case, effectively downgraded to Fair or Poor 

in the office (not given full weight). In such cases, however, 

appropriate remarks are to be entered into the database.

Expanded shifted ratings and the flow measurements 

from which they were developed were compared to each other 

and to the criteria used for determining whether to develop a 

shift (table 19, at end of report). Overall, 20,380 measurementrating pairs were compared. Measurements with negative 

flows were not included in this analysis, although measurements with zero flow were. For 2,482 of these, the measurement was more than 5 percent but less than 8 percent different 

from the rating, and for 1,063 of these, the measurement was 

8 percent or greater different from the rating. The criteria of 

5 and 8 percent are thresholds mandated in USGS methods 

manuals at which flow measurements are rated as Poor and 

Fair, respectively; if measurements are rated Good, the rating 

is to be developed or shifted to within 5 percent of the flow, 

if the measurement is rated Fair, the rating is to be within 

8 percent, and only if a measurement is rated Poor is the rating 

allowed to diverge more than 8 percent from the measurement 

(Rantz and others, 1982; Turnipseed and Sauer, 2010). 

Measurement quality assessments have always accounted 

for factors including flow distribution in the section, turbulence, bed roughness, changes in flow during the measurement, and equipment malfunctions. The hydrographer has 

always been expected to determine the departure between 

the measurement and the rating in the field immediately after 

the measurement, and to explain and document it relative to 

control conditions, flow measurement quality, and less frequently, stage measurement quality. In practice, problems with 

measurements are sometimes discovered in the office; when 

this happens, the database is to be updated to include remarks 

describing the problem.

The overall rate of unexplained measurement-rating 

divergence was 3.6 percent. To be counted as divergent, a 

measurement rated Good diverged more than 5 percent from 

the shifted rating or a measurement rated Fair diverged more 

than 8 percent from the shifted rating; measurements rated 

Poor were not counted. However, at seven sites, the rate of 

unexplained divergence was greater than 10 percent, and the 

maximum rate was 18 percent. For these sites, the retrievals of 

both ratings and measurements were checked and verified. 

The percentage of unexplained measurement-rating divergence was essentially uncorrelated among sites with other 

stability metrics. However, several of the sites with the lowest 

rates of unexplained divergence were among the most stable 

sites as shown by R2 of GAMs or any of the AltFlow error 

terms (table 20, available online). One potential explanation 

for high rates of unexplained measurement-rating divergence 

at some sites could be that, if the stage record was poor at the 

site and large amounts of record would have to be estimated, 

there would be little practical reason to develop shifts at the 
Stability Metrics and Their Relations to Each Other and to Basin Characteristics 35

site. However, it was particularly poorly correlated with percentage of estimated days (R2

 = 0.0085), which does not support this idea. Another possible explanation is that, at some of 

these sites, the daily value record itself was judged to be Fair 

or Poor in the qualitative assessments that are published in 

Annual Water-Data Report remarks for each streamgage (U.S. 

Geological Survey, 2016b). Although hydrographers often 

consider these assessments to be a major part of working a 

flow record, the assessments are not captured in NWIS.

Examples of AltFlow Hydrographs

All AltFlows are plotted in a series of hydrographs 

for the period of record in appendix 4. In total, more than 

2,620 streamgage years of AltFlow record were developed at 

the 174 streamgages in the study (table 21, at end of report). 

Total length of AltFlow record ranged from 71 days through 

8,387 days.

Hydrographs for four selected streamgages in the 

Shenandoah River Basin are shown as examples of several 

patterns that appear in these hydrographs (plate 3). First, 

although the period of record differs among streamgages, one 

site (01628500, South Fork Shenandoah River near Lynnwood, VA) has a nearly complete record owing to the availability of historical shifts and ratings since the 1991 water 

year. For the other three streamgages (01620500, North River 

near Stokesville; 01629500, South Fork Shenandoah River 

near Luray; and 01631000, South Fork Shenandoah River at 

Front Royal) AltFlow periods of record began in 2002, even 

though flow daily values are available continuously throughout the entire study period. All hydrographs are shown on 

the same time scale to simplify comparison among sites for 

simultaneous events. Values of Qsame and Qprev are shown in 

units of log10 of flow in ft3/s; negative values on the plots 

reflect values of flow between 0 and 1 ft3/s. Values of zero 

flow are undefinable on these plots and are shown as lines that 

drop to the bottom of the scale.

At all sites, Qsame becomes available before Qprev. Differences in Qsame and Qprev are straightforward to identify as the 

parts of the plot where the two lines separate. At most sites, 

differences are greatest and most common at low or mediumlow flows. At all sites, differences are more pronounced in 

some years than others. At one of the sites (01620500, North 

River near Stokesville), Qprev went to zero, although Qsame did 

not, indicating a fairly large change that was probably the 

result of scour. This same site also showed differences in Qsame

and Qprev at medium and high flows, which are unlikely without scour and fill on the control. In contrast, at the sites where 

differences appear only at low flows, the shifts and rating 

changes could be the result of algae and macrophyte growth 

or leaf accumulation. These observations are consistent with 

site descriptions (table 8). 

Dates of measurements are shown as green dots plotted at the minimum observed value of Qsame (plate 3). These 

are the dates when Qsame and Qprev diverge from each other, 

or when the lines representing them cross on the plot. The 

AltFlow changes represent snapshots on the dates of flow 

measurements. Large changes, particularly at low flows 

at sites where shifting is caused by algae and macrophyte 

growth, were not necessarily as abrupt as they are depicted 

in these plots and were probably prorated through time from 

magnitudes of zero to the value that was in effect when the 

measurement was made. Likewise, at sites where shifting is 

done to account for plant growth, measurements may or may 

not have been made when shifts were at their maxima, and 

there is no particular reason to think that the AltFlows and the 

hydrographs derived from them capture maximum shifts very 

often.

Stability Metrics and Their 

Relations to Each Other and to Basin 

Characteristics

The set of AltFlow data was large and complex enough 

that no single metric summarized it completely. Several different summary metrics were computed, and they describe 

different aspects of rating stability. Additionally, other metrics 

of rating stability were considered, including average number 

of days that base ratings remained in effect, R2 from the GAM 

models of flow measurements, percentages of winter and total 

days estimated, and percentage of measurements at a site with 

unexplained divergence from the expanded shifted rating in 

effect when the measurement was made. These metrics have 

different strengths and weaknesses. Some of them are clearly 

meaningful, whereas others appear not to be. The latter group 

is discussed to show that the metrics were, in fact, considered 

and examined. Because different aspects of rating stability 

could be relevant to management and planning actions, overall 

totals of these stability metrics are compiled into a colorcoded, sortable table (table 20). 

Description of Stability Metrics

Fifteen stability metrics were considered. One was 

derived from hydrographer stability ratings, 7 were computed 

from AltFlows, and 7 were computed from other data.

Stability Class

1. Stability class, as described by hydrographers, was 

metric 1 (table 22, at end of report); it was used for 

verification and as a basis of comparison for all the other 

metrics. Senior hydrographers participated in interviews, 

and later were presented with questionnaires and asked 

to rate the control stability for all the streamgages they 

personally were familiar with as Excellent, Good, Fair, 

or Poor. (Instructions for the questionnaire are given 
36 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

in table 23.) The descriptive evaluations were converted to numeric values of 4, 3, 2, and 1, respectively, 

and averaged. Ten senior hydrographers answered 

the questionnaire. 

A total of 397 assessments were received. Considering all 

assessments for all sites, 32 were Excellent, 220 were Good, 

109 were Fair, and 36 were Poor. Average scores for sites 

ranged from 1 to 4. Most (112) sites were assessed by 2 different hydrographers; 13 sites were assessed by only 1 hydrographer, 31 were assessed by 3 hydrographers, 13 sites were 

assessed by 4 hydrographers, and 3 sites were assessed by 5 

hydrographers. Of the 47 sites with 3 or more assessments, 

hydrographers came to a consensus on stability for 16 of them. 

Of the 112 sites with two assessments, the two hydrographers 

agreed for 47 of them. At 15 sites, hydrographers differed 

in their assessments by a full stability class, meaning that at 

least one hydrographer considered the site in question Excellent, and at least one other hydrographer considered it Fair, or 

one considered the site Good, and another considered it Poor. 

There were no sites that one hydrographer considered Excellent but another one considered Poor.

Hydrographers who independently evaluated the same 

streamgages gave them different scores and ranked them differently. Some hydrographers had more positive or negative 

assessments overall than others; some individuals considered 

Table 23. Instructions to senior hydrographers for answering a control and rating stability questionnaire, for Virginia streamgages 

active September 30, 2013. 

[Assessments made on the basis of these responses are given in table 22. Descriptions of control and rating stability classes are in bold type.]

The answers for this questionnaire are to be used to classify selected streamgages in Virginia on the basis of overall control stability and 

rating quality, particularly with respect to how reliable provisional data are in real time and how likely provisional data are to match final 

data at each site. Please consider factors including frequency of shifting, magnitude of shifts or rating changes needed, predictability of 

changes, duration of stable periods, quality of the measuring section, site characteristics that affect the completeness and quality of stage 

data, or anything else that affects the likelihood of changes from provisional data to final data. 

Please provide an answer for each streamgage that you’re familiar with, and skip streamgages you’re not familiar with. Because several 

stream characteristics of interest are related to location, some field offices will have many good or excellent sites and few fair or poor 

sites, while other field offices will have many fair or poor sites and few good or excellent sites. There is no particular reason that the 

overall network would be divided equally into excellent, good, fair, and poor sites, so don’t worry about having more in one category than 

another. Different people have different expectations for excellent, good, fair, and poor sites, but because common criteria are desirable 

for this questionnaire, please consider the following criteria.

An excellent site is one where the base rating is 

well defined, may remain stable for years, and is only 

likely to change in response to a major event. Shifts 

are small and are made in response to predictable 

seasonal factors. Scour and fill on the control is rare or 

minor. Some record may be affected by ice, but if so, it 

is easy to identify in real time.

A good site is one where the base rating is well 

defined, but it may change every few years. It might be 

subject to regular seasonal shifting because of weeds, 

algae, or leaves, but the shifts are moderate, predictable, and practical to define. Alternately, it might have 

occasional or moderate scour-fill shifting.

A fair site is one where the rating changes fairly 

frequently. The control may have fairly large weed or 

leaf shifts, which may sometimes be difficult to characterize throughout the full range of stage. It may have 

substantial scour-fill shifting, or scour and fill of the 

control occasionally may be large. The stream bank 

may only be moderately stable, and occasionally a tree 

or other obstruction may catch on the control. Beavers 

may occasionally be present, but they do not tend to 

build dams on the gage control very often.

A poor site may be one where the control changes 

constantly. The base rating may not be practical to 

define because of frequent changes to the control. 

Alternately, the control may not change extraordinarily often, but the changes are large and unpredictable. The control may scour and fill multiple times 

between visits. Banks may be highly unstable, and this 

may result in logs catching on the control frequently 

and washing off between visits. The timing of these 

events may be difficult to determine after the fact. 

Beavers may build dams on the control frequently.
Stability Metrics and Their Relations to Each Other and to Basin Characteristics 37

most of the controls to be Fair or Poor and few to be Excellent, 

whereas others considered many of their controls to be Good 

or Fair and few to be Poor. 

Some of the inconsistency of evaluations was likely the 

result of changes to streams through time; individuals who 

worked at the same streamgages at different times experienced 

different conditions and were left with different impressions. Another cause of inconsistent evaluations was lack of 

a common frame of reference. No individual hydrographer 

in Virginia claimed to be familiar with every streamgage in 

the network. Of the 174 streamgages included in this study, 

the most that any individual evaluated was 100. However, as 

shown by the lack of agreement on stability of controls rated 

by more than one hydrographer, different individuals, even 

experts, are prone to make subjective assessments differently. 

Despite these weaknesses, this metric alone might be 

acceptable for certain applications, such as internal allocation 

of workload within a field office. It was used as verification 

for the quantitative metrics discussed below. Consistency 

in subjective assessments of the stability of controls is not 

essential to consistent computation of flow data, which instead 

requires consistent responses to measured changes regardless 

of whether or not a particular streambed is stable.

Metrics Derived from AltFlows

The AltFlow tables are summarized using seven different 

stability metrics.

2. The average of daily percent errors, or

Q Q

Q

n

i

n prev same

same

  . (1)

This method for computing percent error works well for 

datasets with small error terms. However, it is problematic when error as a percentage of Qsame is relatively 

large. Error terms have larger magnitudes when Qsame

is greater than (>) Qprev than when Qprev > Qsame. This 

is because the magnitude of error as a percentage of 

Qsame is asymptotic as it approaches 100 percent when 

Qsame > Qprev but unlimited when Qprev > Qsame. When the 

difference between Qprev and Qsame exceeds the magnitude 

of flow, daily percent error is wildly different, depending on whether Qprev > Qsame or Qsame > Qprev. When these 

values are averaged together, values for days when 

Qsame > Qprev dominate values when Qprev > Qsame. Rating changes that exceed the magnitude of flow are not 

especially common overall (they represent 1.3 percent of 

observations in the overall dataset), but they are common 

at some sites (table 20). At streamgage 02037000, James 

River and Kanawha Canal near Richmond, VA, the 

absolute value of Qprev – Qsame exceeded that day’s Qsame

on 21.5 percent of days, and at streamgage 01646305, 

Dead Run at Whann Avenue near McLean, VA, the 

absolute value of Qprev – Qsame exceeded that day’s Qsame

on 19.5 percent of days. Three more sites had differences 

exceeding Qsame more than 10 percent of the time, and 

11 sites had differences exceeding Qsame between 5 and 

10 percent of the time. Similar but nonidentical patterns 

were present when error was compared to Qprev. The 

same two sites (02037000 and 01646305) had the highest 

percentages of difference exceeding flow and had more 

than 10 percent of days when difference exceeded flow. 

Nine instead of 11 sites had between 5 and 10 percent of 

days when differences exceeded Qprev. 

Another, albeit smaller, problem with the average of 

daily errors as a metric is that, when the value of Qsame

is zero but flow is indicated for Qprev, values for error 

expressed as a percent of Qsame are undefined. This happened at 13 sites in the network and affected 697 days of 

record (table 15). Forty-two percent of these days came 

at one site, 02037000, James River and Kanawha Canal 

near Richmond, VA. The largest of these non-zero values 

of Qprev on days with Qsame of 0.00 were also observed 

at this site; mean and maximum were 136 and 643 ft3/s, 

respectively. At the other sites on days with Qsame of 

0.00 but non-zero values of Qprev, mean values of Qprev

by site ranged from 0.01 to 16.9 ft3/s, and maximums 

ranged from 0.01 to 19 ft3/s. For purposes of computing mean percentage error, these values were excluded, 

but as these values all, by definition, came at low flow, 

their exclusion removed valuable information from 

the analysis.

Problems with computation aside, this metric (average 

of daily percent errors) is highly sensitive to changes in 

ratings that affect low flows, especially the lowest flows. 

Differences in the lowest flows tend to be small in magnitude but high in percentage. Depending on the users’ 

priorities and needs, this sensitivity could be useful or 

problematic. It is presented by month and flow percentile 

in table 24 (available online) and in total for each site in 

table 20.

3. Σ Error / ΣQ

This is a flow-weighted average of error. Positive and 

negative errors cancel each other out when added 

together so that cyclic or fluctuating rating changes, 

such as those caused by algae or macrophyte growth 

and death, leaf accumulation and removal, or scour and 

fill, tend to cancel each other out. To the extent that such 

changes are predictable, then, this metric might filter 

them out and quantify unpredictable rating changes. 

This tendency may be more meaningful for periods of 1 

or 2 years than for the entire period of record. Over the 

entire period of record, the metric is potentially useful 

for determining whether a rating has changed more in 

one direction than another, as in the case of a stream 
38 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

that has been downcutting or aggrading at a control; 

however, this type of change is more readily identifiable 

through the time-series plots of measurement residuals. 

It is presented in total for each site (table 20), but a more 

detailed table of this metric is not presented.

4. Σ |Error| / ΣQ

This is a flow-weighted average of absolute error. One 

bias is that cyclic or fluctuating rating changes, such as 

those caused by algae or macrophyte growth and death, 

leaf accumulation and removal, or scour and fill, are 

counted (1) when they form and (2) when they dissipate. 

It is also sensitive to rating changes that affect high flows 

and therefore result in large changes in flow magnitude. 

It is presented in total for each site (table 20), but a 

detailed table of this metric is not presented. 

5. RMSE on log-transformed flow values

When flow data are log-transformed and RMSE is computed on the transformed data, the result is an error term 

that weighs errors throughout the range of flows more 

equally than one computed on untransformed data. One 

shortcoming of this is that values of zero flow, whether 

for Qprev or Qsame, are undefinable for log-transformation. 

When both Qprev and Qsame were equal to zero, the error 

term was manually set equal to zero, and the day’s 

record was included in summary tables. RMSE is presented by month and flow percentile (table 25, available 

online), and in total for each site (table 20).

6. Percentage of days with zero difference between Qsame

and Qprev

A day with no difference in flow between Qsame and Qprev

represents a point on the rating that remained the same 

from one visit to the next. Unlike the other stability metrics that reflect magnitude of rating change, a percentage 

of zero difference treats all rating changes the same. This 

metric therefore is not affected by whether the rating 

changed at high or low flow. Unlike the metrics that 

incorporate flow magnitude, it is not unduly affected by 

infrequent large changes such as those resulting from 

beaver dams, swimmers’ dams, or human activity at 

otherwise stable sites; these are changes that in practice 

would be noticed quickly by hydrographers and waterdata users. 

Total percentage of zero-difference days ranged from 

about15 percent (0165389205, Accotink Creek near 

Ranger Road at Fairfax, which has since been discontinued) to about 89 percent (02011800, Jackson River 

below Gathright Dam near Hot Springs, and 02011490, 

Little Back Creek near Sunrise; table 20). All the sites 

with low percentages of zero-difference days (<40 percent) were on small streams (<100-mi2

 drainage area) 

in northern Virginia or in other parts of Virginia with 

elevation less than 500 feet, or both. Of the 31 sites 

with less than 40 percent of zero difference days, only 

6 sites drained more than 100 mi2, and only 3 sites were 

at elevations above 500 ft. In contrast, of the 30 sites 

where more than two-thirds of the days had zero difference, all but 4 sites were on large streams (>500 mi2

drainage area) or at elevations of more than 1,000 ft, 

or both; 1 of the 4 sites has a bedrock control. There 

were many small, high-elevation sites and several large, 

low-elevation sites with low or medium percentages of 

zero difference.

The percentage of AltFlows with zero difference between 

Qprev and Qsame for each streamgage in the study is shown, 

by month, in table 26 (available online). When zoomed 

out so that the entire table is visible, it displays the entire 

AltFlow dataset. By default, sites (rows) are sorted by 

downstream order number, so that they are grouped by 

basin. Each column represents a month. Green cells 

signify no or few nonzero differences between Qprev and 

Qsame; stated differently, they signify little or no change 

in the rating from measurement to measurement. Red 

cells signify many nonzero differences between Qprev and 

Qsame or that the rating changed between the most recent 

measurement and the previous measurement. While fully 

zoomed out, of course, dates, site identifiers, and values 

are illegible; the table is intended to be used interactively 

onscreen, zooming out to see broad patterns and zooming in to see detail.

7. Percentage of days when the difference between Qsame

and Qprev exceeded Qsame

Essentially the opposite of the percentage of days with 

zero difference, this metric considers only large rating 

changes, those resulting in flow differences of 100 percent or more (table 20). Such changes existed at 90 of 

the sites. At 84 of the sites, this never happened, and at 

another 37 of the sites, it happened less than 1 percent 

of the time. 

In order for the difference between Qprev and Qsame to 

exceed Qsame, Qprev must exceed Qsame. This is caused by 

changes to the control that increase backwater, such as 

fill, macrophyte and algae growth, leaf accumulation, 

and deposition of logs and other woody debris. These 

changes are much more common at low flow than high 

flow; almost one-half of these were days when Qsame was 

less than the D90 (90 percent duration flow; 5,693 days 

of 12,794), and about 93 percent of them were days 

when Qsame was less than the D50 (50 percent duration 

flow; 11,913 days of 12,794). Beaver dams, swimmers’ 

dams, or large logs on the control are among the likeliest types of obstructions that might cause backwater 

at medium or high flows. At low flow, small absolute 

changes to the control can result in large relative changes 
Stability Metrics and Their Relations to Each Other and to Basin Characteristics 39

to the rating, and the majority of the days when the difference between Qprev and Qsame exceeded Qsame were during the time when medium to low flow is typical. Among 

all sites, 10,280 days of 12,794 were during July through 

December, and September was the month with the largest 

number of these days (2,084).

At 30 of the sites where the difference between Qprev and 

Qsame exceeded Qsame, the difference between Qsame and 

Qprev exceeded Qsame more than 2.5 percent of the time, 

or about 9 days per year. These 30 sites with the highest rates of large changes are predominantly either (1) 

small in area—the largest drainage area among them 

is 332 mi2, (2) low in elevation—only 4 of them are at 

elevations greater than 1,000 ft, or (3) both. Seven of the 

sites drain more than 100 mi2, and 6 of them are at elevations below 500 ft. Three of the 4 sites above 1,000 ft 

drain less than 20 mi2. One site (01632000, North Fork 

Shenandoah River at Cootes Store) is neither low nor 

especially small; it is at an elevation of 1,051 ft and 

drains 210 mi2. There, the difference between Qprev and 

Qsame exceeded Qsame 2.8 percent of the time. This site 

was an outlier in several other stability metrics.

Of the 84 sites where the difference between Qprev and 

Qsame never exceeded Qsame, most are on large streams 

or at high elevations. Forty-three sites are at elevations 

greater than 1,000 ft, and 29 drain more than 500 mi2. 

Only 4 are at elevations less than 500 ft and drain less 

than 200 mi2; 1 of the 4 had only 2 years of record, 

which may or may not have been representative of longterm conditions. 

8. Percentage of days when the difference between Qsame

and Qprev exceeded Qprev

At 94 streamgages, the difference between Qsame and 

Qprev exceeded Qprev at least one time; at the other 80, this 

never happened (table 20). Patterns between this metric 

and metric 6 were generally similar. Sixty of the sites 

had non-zero values for both, whereas at 73 sites, the 

difference between Qsame and Qprev never exceeded either 

Qsame or Qprev. 

In order for the difference between Qprev and Qsame to 

exceed Qprev, Qsame must exceed Qprev. This is caused by 

scour and other changes to the control that increase flow 

relative to stage, such as removal of macrophytes and 

algae or the washing away of leaves, logs, and other 

woody debris. The changes to the control are likely to 

result from peaks or high flow pulses but are more likely 

to affect low flows than high flows. About one-fourth 

of the days with Qprev – Qsame > Qprev came when Qsame

was less than the D90 (3,241 days of 12,394), and about 

three-fourths of them came when Qsame exceeded the D50 

(9,616 days of 12,394). Seasonality was less pronounced 

than it was for metric 7. Days when Qprev – Qsame > Qprev

were somewhat less frequent in spring than other seasons 

(2,938 days of 12,394 during March through June), 

but those days were generally fairly evenly distributed 

throughout the year.

Although the overall patterns were similar, this metric 

did not correlate as strongly with metric 7 as one might 

expect; rho was only 0.8772. This metric may be different because at some sites, scour is abrupt and fill is 

gradual, and at others, vice versa. Another possibility is 

that at some sites, algae and macrophyte growth or leaf 

accumulation are gradual, but dissipation is abrupt and 

often accompanied by scour. It is also possible that the 

two metrics are showing more or less the same thing. 

The correlation between them might be low despite the 

metrics showing the same thing because of the large 

number of near-zero observations from each metric that 

correspond with a zero observation for the other. Most 

likely, the two metrics are showing the same thing, but 

the metrics are affected principally by infrequent events 

and are therefore insensitive and imprecise.

Other Metrics

Seven additional metrics, 9–15, were considered. 

9. Proportion of daily values that were estimated

This was one of the simplest metrics to compute and was 

determined from the series of daily values (Qmeas) itself; 

it was just the number of days per site with a remark 

code of “A:e” (table 13) divided by total days of record, 

computed for the period when AltFlows were available 

for each site (table 20). Total estimated daily values are 

most affected by issues with the stage record, including recurring problems with sedimentation related to 

the location of the stilling-well intake or bubbler orifice, 

isolated problems with equipment failure, and in winter, 

ice effect. At one site, the stream downcut at the control 

and left the stilling-well intakes out of the water for several days. Strictly speaking, this metric was not thought 

to be directly related to rating stability. This relation 

was investigated because sediment deposition is related 

to scour-and-fill shifting and to many problems with 

stilling-well intakes and bubble-gage orifices.

10. Proportion of daily values in winter that were estimated

The three months with the highest rates of estimated 

record were, in order, January, February, and December. 

Although intakes and orifices may be plugged during 

winter, and equipment failure is more common during 

winter than the rest of the year, the great majority of 

estimated days in winter are likely caused by ice effects. 

Ice effects may take the form of anchor ice accumulating 

on the control, a total freeze over of a stream, and less 
40 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

commonly, ice jams. All of these can result in backwater 

in the gaging pool, which makes the stage-flow relation invalid until the ice melts or washes out. Since flow 

cannot be computed with the rating during these periods, 

it is estimated as mean daily flow. Like total estimated 

daily values, winter estimates should not, strictly speaking, be related to control and rating stability. This metric 

is presented in total by site in table 20.

11. Average days that base ratings were in effect

The average number of days that base ratings were in 

effect at each site might seem to be a useful stability 

metric. However, it was almost completely uncorrelated 

with other metrics (R2 = 0.0069 with percent zero difference and 0.0451 with total RMSE for AltFlows), highly 

affected by differences among field offices and individual hydrographer’s preference, and affected by length 

of record at the streamgages. This metric is presented by 

site in table 20.

12. R2 of most recent GAMQ model

Many of the sites had multiple rating families, as 

described in previous sections of this report. Only the 

most recent rating family was included and is presented 

by site (table 20). GAM models were fit to gage height 

and flow from flow measurements; this was one of the 

three error terms from these models that was considered 

to be a candidate stability metric.

13. R2 of most recent GAMGH model

This is the second of three potential stability metrics 

derived from the analysis of variability of flow measurements; it was derived from GAM models that fit gage 

height as a smoothing function of flow. It was considered 

but rejected as a candidate stability metric. Its correlation 

with the other metrics was investigated. It is presented by 

site for the most recent rating family (table 20).

14. Spearman’s rho of the most recent rating family

This was the third of three potential stability metrics 

derived from analysis of variability of flow measurements subset by rating family. Unlike the other two, it 

had nothing to do with the GAM models, and as a rankbased statistic, it would be exactly the same regardless 

of which variable was considered to be dependent. It was 

considered but rejected as a candidate stability metric. Its 

correlation with the other metrics was investigated. It is 

presented, by site, for all rating families (table 13).

15. Percentages of measurements with unexplained divergence from the rating

Described previously, the rate of unexplained divergence 

from the rating was lowest at some sites described as 

having stable ratings and excellent stage record. It was 

considered but rejected as a candidate stability metric. 

Its correlation with the other metrics was investigated. 

It is presented by site, for the most recent rating family 

(table 20).

Relations Among Stability Metrics

Relations among stability metrics were investigated using 

three types of analysis. Spearman’s rho correlation coefficients 

were determined among sites for all pairs of metrics and are 

presented in table 27, sorted by strength of correlation with 

stability class. Spearman’s rho was chosen because the stability metrics had different frequency distributions and a rankbased statistic eliminated the need to transform them. The stability classes were assigned numeric values of 1, 2, 3, and 4, 

corresponding to Poor, Fair, Good, and Excellent, respectively, 

for purposes of computing the correlations. The correlations 

between stability class and the quantitative metrics were weak. 

No correlation had an absolute value greater than 0.5. The 

six metrics most strongly correlated with stability class were 

all derived from AltFlows; these were AltFlow absolute error 

divided by flow, difference > Qsame, RMSE, difference > Qprev, 

percentage of average daily error, and percentage of zero 

difference of AltFlows. The R2 of GAMQ was next; no other 

metric had a rho with an absolute value greater than 0.3. These 

correlations are illustrated using a scatterplot matrix (plate 4).

Correlations among most of the error terms derived 

from AltFlows were generally the strongest of the entire set. 

As an example, the magnitude of Spearman’s rho between 

AltFlow RMSE and 5 of the other 6 such terms ranged from 

0.75 to 0.90. 

The percentage of AltFlow daily error averaged was 

surprisingly strongly correlated with stability class (-0.4248) 

and some other metrics (|rho| > 0.6 for four other metrics), 

considering the problematic nature of its computation as 

discussed in its description (section “Metrics Derived from 

AltFlows”). Percentage of daily error averaged seems to be 

sensitive to relatively large differences in low flows, and if no 

other metrics sensitive to differences at low flow were available, it might be worth retaining despite problematic computation. However, AltFlow RMSE is only moderately affected 

by large-magnitude rating changes because it is computed 

and reported in log space. Percentage of zero-difference days 

is indifferent to flow magnitude, but the two metrics, based 

on differences exceeding magnitude of flow, are dominated 

by rating changes at low flow. In light of this, percentage of 

daily error averaged is probably too problematic a metric to 

consider as meaningful, although it is retained in this report 

for the purposes of documenting how it was considered.

Another candidate metric derived from AltFlows that 

is not clearly meaningful is the sum of error divided by the 

sum of flow. Its strongest correlation with any other proposed 

stability metric was -0.3248 with percentage of daily error 
Stability Metrics and Their Relations to Each Other and to Basin Characteristics 41

Table 27. Correlation matrix of Spearman’s rho correlation coefficients for proposed rating-stability metrics developed from daily flows, shifted ratings, and flow measurements for streamgages in Virginia, water years 1991–2013.[summary.numeric, Stability class, where 4 = excellent, 3 = good, 2 = fair, and 1 = poor.; RMSE, Root-mean-square error of AltFlows, in log units; diff.gt.Qsame, Proportion of days when Qprev – Qsame > Qsame; abs.error.Q, For AltFlows, sum of absolute values of error divided by sum of flow; pct.error.avgd, Daily percent error, averaged; diff.gt.Qprev, Proportion of days when Qprev – Qsame > Qprev; gamQ.R2, R2 of GAM models of flow as a function of gage height from flow measurements, for the most recent rating family; pct.zero.diff, Proportion of days of AltFlow record when Qprev = Qsame; RatFam.rho, Spearman’s rho for gage height and flow from flow measurements, for the most recent rating family; gamGH.R2, R2 of GAM models of gage height as a function of flow from flow measurements, for the most recent rating family; pct.est, Percentage of daily values that were estimated; days.per.rat, Average time base ratings were in effect, in days; pct.est.winter, Percentage of daily values in winter that were estimated; pct.unexp.dev, Percentage of flow measurements that deviated from ratings by more than specified by Rantz and others, 1982; error.Q, For AltFlows, sum of error divided by sum of flow; >, greater than; AltFlow, alternative flow; GAM, generalized additive model; R2, coefficient of determination; 

Qprev, the flow value from the shifted rating table in effect at the time 

of the previous flow measurement that corresponds to the gage height of each day’s daily flow value; 

Qsame, the flow value from the shifted rating table used to compute the daily flow value at the time of 

the most recent flow measurement that corresponds to the gage height of each day’s daily flow value]

Parameter summary. numeric abs. error.Q diff.gt. Qsame RMSE diff.gt. Qprev pct.error. avgd pct.zero. diff gamQ. R2 gamGH. R2 pct.est RatFam. rho days.per. rat pct.est. winter error.Q pct.unexp. dev

summary.

numeric 1.0000 -0.4969 -0.4762 -0.4732 -0.4381 -0.4248 0.3944 0.3790 0.2982 -0.2982 0.2686 0.1939 -0.1676 -0.1182 -0.0903

abs.

error.Q -0.4969 1.0000 0.7296 0.8523 0.7436 -0.6747 -0.8508 -0.6535 -0.5737 0.4827 -0.6106 -0.2265 0.3326 0.1903 0.1937

diff.gt.

Qsame -0.4762 0.7296 1.0000 0.8640 0.8772 -0.7969 -0.5846 -0.6224 -0.5074 0.4634 -0.4728 -0.2445 0.3151 0.1236 0.2748

RMSE -0.4732 0.8523 0.8640 1.0000 0.8979 -0.7584 -0.7525 -0.6960 -0.5597 0.5200 -0.5589 -0.2553 0.3548 0.0911 0.2278

diff.gt.

Qprev -0.4381 0.7436 0.8772 0.8979 1.0000 -0.6754 -0.6226 -0.6589 -0.5335 0.4575 -0.5077 -0.2809 0.3182 0.0641 0.2491

pct.error.

avgd -0.4248 -0.6747 -0.7969 -0.7584 -0.6754 1.0000 0.5936 0.5760 0.4676 -0.4948 0.4264 0.1487 -0.3982 -0.3248 -0.2000

pct.zero.

diff 0.3944 -0.8508 -0.5846 -0.7525 -0.6226 0.5936 1.0000 0.5760 0.4913 -0.4273 0.5510 0.0936 -0.3157 -0.0951 -0.1038

gamQ.

R2 0.3790 -0.6535 -0.6224 -0.6960 -0.6589 0.5760 0.5760 1.0000 0.9020 -0.4077 0.7931 0.2131 -0.3577 -0.0430 -0.1437

gamGH.

R2 0.2982 -0.5737 -0.5074 -0.5597 -0.5335 0.4676 0.4913 0.9020 1.0000 -0.3147 0.7518 0.1684 -0.2778 -0.0728 -0.1246

pct.est -0.2982 0.4827 0.4634 0.5200 0.4575 -0.4948 -0.4273 -0.4077 -0.3147 1.0000 -0.3170 -0.1197 0.8584 0.0912 0.1347

RatFam.

rho 0.2686 -0.6106 -0.4728 -0.5589 -0.5077 0.4264 0.5510 0.7931 0.7518 -0.3170 1.0000 0.2053 -0.2353 -0.0883 -0.1696

days.per.

rat 0.1939 -0.2265 -0.2445 -0.2553 -0.2809 0.1487 0.0936 0.2131 0.1684 -0.1197 0.2053 1.0000 0.0116 0.1081 -0.1512

pct.est.

winter -0.1676 0.3326 0.3151 0.3548 0.3182 -0.3982 -0.3157 -0.3577 -0.2778 0.8584 -0.2353 0.0116 1.0000 0.0685 0.0515

error.Q -0.1182 0.1903 0.1236 0.0911 0.0641 -0.3248 -0.0951 -0.0430 -0.0728 0.0912 -0.0883 0.1081 0.0685 1.0000 0.1334

pct.unexp.

dev -0.0903 0.1937 0.2748 0.2278 0.2491 -0.2000 -0.1038 -0.1437 -0.1246 0.1347 -0.1696 -0.1512 0.0515 0.1334 1.0000
42 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

averaged. The weakness of correlation between this metric and 

the others is likely due to positive and negative errors canceling each other out. 

Two other proposed stability metrics that correlated only 

weakly with any other metric, including stability class, were 

percentage of flow measurements with unexplained deviation 

from the rating and length of time that base ratings were in 

effect. The length of time for base ratings to remain in effect 

would at first seem to be an obvious metric for rating stability, 

if not the most obvious imaginable. That it is at most weakly 

correlated with other stability metrics is a result of the role of 

hydrographer preference in achieving the same final expanded 

shifted rating tables through different combinations of ratings 

and shifts. The percentage of measurements with unexplained 

deviation from the rating is not such an obvious candidate for 

a stability metric. It emerged as a candidate metric during data 

exploration and seemed promising enough to include for this 

level of screening; it is apparently fairly arbitrary.

The two candidate metrics based on percentages of estimates were strongly correlated to each other (rho = 0.8584). 

This is reasonable because a disproportionate amount of 

estimated daily flow values comes in the winter. Both metrics 

were weakly correlated with stability class, -0.2982 for total 

estimates and -0.1676 for winter estimates. Total estimates 

were moderately correlated with R2 of GAMQ and several of 

the AltFlow-derived metrics, with the absolute value of rho 

as high as 0.5200 for RMSE and greater than 0.4 for six of 

the other metrics. Winter estimates had a weaker correlation 

with each of the other candidate metrics than did total estimates. Although these two candidate metrics are, as expected, 

weakly correlated with measures that are truly reflective of a 

streamgage’s stage-flow relation, they still provide valuable 

information on the reliability of a streamgage in real time and 

are retained for further analysis. 

The comparisons among rating-stability metrics included 

comparisons of error terms for different GAM models that 

were used to select the R2 of GAMQ as the preferred model 

for fitting flow and gage height from measurements. Of these 

error terms, the R2 of GAMQ is the most strongly correlated 

of the rating family metrics not only to stability class, but to 

all except two of the other proposed metrics. Those two were 

metrics that have already been rejected as not being meaningful are the percentage of unexplained deviation between measurements and ratings and the sum of AltFlow error divided by 

sum of flow. Considering the strength of its relations to other 

metrics, R2 of GAMQ was judged to be the strongest of the 

three rating family metrics under consideration. 

Other stability metrics could have been developed 

from the set of data derived from measurements alone if the 

AltFlows had not been available. For instance, the residuals 

could have been sorted by time, and the number of them that 

exceeded or failed to exceed meaningful thresholds could 

have been counted either in total or in series. Change from 

measurement to measurement could also have been computed. 

Such metrics were not explored in this study, although they 

may have been meaningful, because AltFlows were available. 

Change from measurement to measurement and residuals 

would be considerably easier to compute because data acquisition and management would have been much simpler.

Another type of analysis of these candidate metrics is a 

series of boxplots for each metric, by stability class (fig. 8). 

Boxplots serve as a summary and check on the correlation analysis. They show strong separation between classes, 

defined as the 75th percentile exceeding the median from class 

to class and the median exceeding the 25th percentile from 

class to class, for only one candidate metric, sum of absolute 

error divided by sum of flow. Little or no separation between 

classes is visible for total estimates, winter estimates, AltFlow 

sum of error divided by sum of flow, base rating length, and 

percentage of unexplained deviation between measurements 

and ratings. Boxplots of the remaining metrics all show the 

expected patterns among classes but moderate or mixed separation among classes.

Qprev – Qsame > Qsame shows a stronger correlation with 

stability class than does Qprev – Qsame > Qprev, and the boxplots 

of the former show a greater separation by stability class 

than those of the latter. The two metrics are strongly, if not 

perfectly, correlated with each other (rho = 0.8772), and they 

are likely to be providing largely the same information in 

an imprecise way. Of the two metrics, Qprev – Qsame > Qsame

was selected as the metric that provided a greater separation 

of values.

On the basis of this comparison, seven stability metrics 

were considered to be meaningful and were retained for comparison to site and basin characteristics. Total RMSE between 

log-transformed Qprev and Qsame is affected by the magnitude 

and frequency of rating changes, and the transformation 

weights change throughout the range of flows so that none 

of high, medium, or low flows dominate the statistic. Days 

when Qprev – Qsame > Qsame is a measure of relatively large rating 

changes, most of which come at low flow. The sum of absolute 

AltFlow error divided by total flow is a flow-weighted statistic 

that is strongly affected by large-magnitude rating changes, 

which are predominantly at the high end of the rating; this 

metric is useful in evaluating rating stability relative to total 

volume of water during a period of time. The R2 of GAMQ is 

computed from flow measurements, not rating changes, and 

as such, was fast and easy to compute. Because most of the 

scatter on the GAM graphs is at the low end, R2 of GAMQ is 

most sensitive to variability at the low end of ratings. Unlike 

the various AltFlow metrics, R2 of GAMQ is independent of 

time, and unlike most of them, its magnitude is independent 

of the flow magnitude of the individual error. Percentage of 

days with zero difference between Qprev and Qsame is a measure 

of the frequency of rating change. Percentage of total estimated days and percentage of estimated days in the winter are 

weakly related to control stability, if they are related to it at 

all, but provide information on the overall quality of the flow 

record and on the historical likelihood that winter record was 

affected by ice.
Stability Metrics and Their Relations to Each Other and to Basin Characteristics 43

0

0.05

0.10

0.15

Proportion

of estimated

daily values

-0.05

0

0.05

0.10

0.15

0.20

0.25

Proportion

of estimated

daily values, winter

0.0

0.2

0.4

0.6

0.8

Sum of |Error| /

sum of flow

-0.1

0

0.1

0.2

0.3

Sum of error /

Sum of flow

0

0.2

0.4

0.6

0.8

RMSE of AltFlows,

in log units

0

0.3

0.6

0.9

Proportion of days with 

no difference between 

Q

same

 and 

Q

prev

-0.05

0.05

0.15

0.25

0

0.10

0.20

Proportion of

days when

Q

prev

– Q

same

 > 

Q

same

-0.05

0

0.05

0.10

0.15

0.20

Proportion of

days when

Q

prev

– Q

same

 > 

Q

prev

0.2

0.4

0.6

0.8

1.0

1.2

R2 of GAM model

of flow as a function

of gage height

0.2

0.4

0.6

0.8

1.0

1.2

R2 of GAM model

of flow as a function

of gage height

Daily error, averaged

0

2,000

4,000

6,000

8,000

10,000

Average base rating

length, in days

-0.05

0

0.05

0.10

0.15

0.20

Proportion of

unexplained deviation

0.2

0.4

0.6

0.8

1.0

Spearman's rho for

measurements used

in GAM model

Poor Fair Good Excellent Poor Fair Good Excellent

EXPLANATION

75th percentile

25th percentile

Median

The largest value that does not 

exceed the 75th percentile plus 

1.5 times the interquartile range 

Outlier

The smallest value that does not 

exceed the 25th percentile minus 

1.5 times the interquartile range 

-1.2

0.2

-1.0

-0.8

-0.6

-0.4

-0.2

0

Stability class Stability class

Figure 8. Distribution of proposed stage-flow relation stability and real-time flow reliability metrics by descriptive stability class for 

streamgages in Virginia active on September 30, 2013. (GAM, generalized additive model; R2, coefficient of determination; Qprev, the flow 

value from the shifted rating table in effect at the time of the previous flow measurement that corresponds to the gage height of each 

day’s daily flow value; Qsame, the flow value from the shifted rating table used to compute the daily flow value at the time of the most 

recent flow measurement that corresponds to the gage height of each day’s daily flow value)
44 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

Stability Metrics and their Relations to Site and 

Basin Characteristics

Stepwise multiple regression analysis was done to determine whether relations among the various stability metrics and 

quantitative basin and site characteristics could be determined. 

These relations are weak, and the results of the regression 

models were not meaningful. The basin characteristics are 

those used in Virginia’s most recent low-flow frequency report 

(Austin and others, 2011; https://pubs.usgs.gov/sir/2011/5143/

tables/Table_09.xlsx). For four stability metrics (percentage of 

zero difference days, total site AltFlow RMSE, R2 of the GAM 

models for the most recent rating family at each site, and days 

when Qprev – Qsame > Qsame), regression models developed using 

stepwise regression had low multiple R2 values, ranging from 

0.3599 to 0.5542, even though the models included between 7 

and 16 independent variables. Stepwise regression is controversial and is criticized when it is used to develop overfitted 

models that by coincidence have good error terms but prove 

not to be reproducible. In this case, however, the error terms 

were poor, indicating weak relations between stability metrics 

and basin characteristics, which is not a commonly criticized 

outcome for stepwise regression. Variables representing basin 

size, elevation, location (latitude and longitude), multiple 

physiography terms, and multiple impervious surface terms 

were identified as being weakly related to more than one 

stability term. 

Review of scatterplot and correlation matrices also 

indicated few strong correlations between stability terms and 

basin characteristics (plate 5; table 28). The strongest correlation (Spearman’s rho) between any stability metric and basin 

characteristic was -0.6655, between percentage of days when 

Qsame – Qprev > Qsame and longitude; in this case, large rating 

changes were common in eastern Virginia and rare or nonexistent in western Virginia. Weak correlations are to be expected 

with a dataset characterized by threshold effects and where 

many of the metrics under analysis include a high proportion 

of values that are similar. Highly local conditions, the configuration and composition of the streambed at a single cross section, are of the greatest importance to control and rating stability. Favorable local conditions may be found in isolation even 

in areas where stream conditions are generally unfavorable for 

streamgaging. Because only a single favorable cross section 

is needed for each streamgage, favorable conditions may be 

found or created in most streams where data are needed.

Relations between channel characteristics at high, 

medium, and low flows and stability metrics were explored. 

Cross-sectional area, stream depth, width, and velocity were 

determined for D1, D50, and D90 for the sites in the study 

from relations between these characteristics and flow in the 

flow measurement dataset. These values were then used to 

generate power curves against drainage area, and residuals for 

all these power curves were captured and included in exploratory analysis. Width-to-depth ratios were also determined 

for D1, D50, and D90. Scatterplot matrices were constructed, 

and Spearman’s rho correlation coefficients were determined 

among all the stability metrics and channel characteristics. The 

strongest relations were slightly stronger than those between 

stability metrics and basin characteristics but were still too 

weak to use for screening candidate streamgage locations 

or other actions. The maximum magnitudes of Spearman’s 

rho in the matrix were about –0.72 between stream width 

at D90 and three metrics—RMSE, Qsame – Qprev > Qsame, and 

Qsame – Qprev > Qprev. For all three, stability increased as width 

increased. As this was still a weak correlation, it was not pursued further during this study. 

Caveats, Limitations, and Suggestions 

for Further Study

Several important sources of error in provisional flow 

data that are corrected in final flow data are missed by the 

process used to develop AltFlows. Most important and common are errors that are not caused by changes to the control 

and therefore are not corrected by changing ratings or shifts. 

These include ice-affected flows or missing records, which 

generally are estimated by hydrographic comparison to other 

streamgages. These errors might be corrected or at least 

adjusted, or daily flows might be estimated for the period that 

was in error. 

Reliability of the stage record is equal in importance with 

rating stability in their effects on the reliability of a site’s flow 

data in real time. The likelihood of plugged intakes or buried 

or exposed orifices is a function of the frequency of sediment deposition at a given point in a stream and, as such, is a 

characteristic of a given site. A streamgage may have a stable 

control but still be prone to recurring problems with the stage 

record that result in unreliable provisional data. The method 

developed to estimate Qprev in this study does not account for 

problematic stage records.

Another difference between provisional and approved 

data not accounted for by the AltFlow procedure is that 

expanded shifted ratings were selected as snapshots at the 

times when flow was measured and the tens of thousands of 

other rating changes were ignored. Days when measurements 

were made have no particular relevance to the beginning 

or ending of shifts and rating changes. As discussed previously, about one-third (7,346 of 23,126) of shift entries began 

on days when flow was measured, and of these, 2,679 were 

apparently procedural entries for shifts that were implemented 

in multiple steps throughout the day. Forty-one percent of 

unique shifts (6,842 of 16,853) began on days of peaks, either 

floods or high-flow pulses, and another 7 percent (1,144 of 

16,853) began the day after a peak. Many of the shifts that 

began on days when measurements were made began on 

days of peaks and high-flow pulses. Prorating certain types of 

shifts through time is routine; the AltFlow procedure does not 

account for these changed shifts. As a result, the AltFlow time 

series is unlikely to have much relation to provisional data as 

they initially appeared on the web, with the possible exception 
Caveats, Limitations, and Suggestions for Further Study 45

Table 28. Correlation matrix of Spearman’s rho correlation coefficients for selected rating stability metrics and selected basin characteristics for streamgages active in Virginia, September 30, 2013.[avg.stability.score, Average of perceived stability class, where 4 = excellent, 3 = good, 2 = fair, and 1 = poor.; RMSE, Root-mean-square error of AltFlows, in log units; diff.gt.Qsame, Proportion of days when Qprev – Qsame > Qsame; abs.error.Q, for AltFlows, sum of absolute values of error divided by sum of flow; pct.error.avgd, Daily percent error, averaged; diff.gt.Qprev, Proportion of days when Qprev – Qsame > Qprev; gamQR2, R2 of GAM models of flow as a function of gage height from flow measurements, for the most recent rating family; pct.zero.diff, Proportion of days of AltFlow record when Qprev = Qsame; pct.est, Percentage of daily values that were estimated; pct.est.winter, Percentage of daily values in winter that were estimated; >, greater than; GAM, generalized additive model; AltFlows, alternative flows; Qprev, the flow value from the shifted rating table in effect at the time of the previous flow measurement that corresponds to the gage height of each day’s daily flow value; Qsame, the flow value from the shifted rating table used to compute the daily flow value at the time of the most recent flow measurement that corresponds to the gage height of each day’s daily flow value]

Basin 

characteristic avg.stability.score abs.error.Q diff.gt.Qsame RMSE diff.gt.Qprev pct.error.avgd pct.zero.diff gamQ.R2 pct.est pct.est.winter

DRNAREA 0.2732 -0.5721 -0.5117 -0.5312 -0.5606 0.4745 0.4573 0.5522 -0.4283 -0.4753

LOGDA 0.2732 -0.5721 -0.5117 -0.5312 -0.5606 0.4745 0.4573 0.5522 -0.4283 -0.4753

ELEV 0.4617 -0.5464 -0.6221 -0.5927 -0.5522 0.5414 0.5099 0.3917 -0.4742 -0.2771

BSLOPE 0.3818 -0.5313 -0.5112 -0.5139 -0.4586 0.4446 0.5041 0.3447 -0.4019 -0.2150

BASINPERIM 0.2843 -0.5967 -0.5321 -0.5650 -0.5848 0.4932 0.5029 0.5557 -0.4710 -0.5030

LAT_CENT -0.0411 0.3544 0.4318 0.4756 0.4378 -0.3961 -0.3320 -0.4004 0.4648 0.5061

LONG_CENT 0.3857 -0.5477 -0.6655 -0.6514 -0.6111 0.5792 0.4758 0.4530 -0.5539 -0.4132

ELEV_PPT 0.3704 -0.3309 -0.4792 -0.4457 -0.4028 0.3861 0.3102 0.2147 -0.3735 -0.1630

PIEDMONT -0.1195 0.0344 0.0451 0.0283 -0.0026 -0.0111 -0.0715 0.1309 0.0622 -0.1540

BLUERIDGE 0.0551 -0.1789 -0.2198 -0.1866 -0.1942 0.3202 0.1752 0.2323 -0.0821 -0.0768

V.R 0.4943 -0.4990 -0.5035 -0.5010 -0.4630 0.4164 0.4267 0.3007 -0.4307 -0.3273

APP_PLAT -0.0200 -0.1941 -0.1496 -0.1693 -0.1549 0.1379 0.1384 0.0127 -0.2308 -0.2121

MESOZOIC 0.0313 -0.0271 -0.0106 -0.0150 -0.0547 0.1111 0.0204 0.1885 0.0782 0.0087

WINTER_PRECIP -0.0527 -0.2824 -0.2924 -0.3764 -0.3083 0.3059 0.3208 0.3128 -0.3284 -0.3943

INTENS_2Y24 -0.2347 0.0649 0.0315 0.0501 0.0376 0.0754 0.0082 0.0899 0.1524 0.0157

IMPERV_0 0.0230 -0.0399 0.0657 0.0161 0.0545 -0.1838 0.0361 0.0515 0.0277 0.0009

IMPERV_1.5 0.0442 0.0081 -0.0669 -0.0635 -0.0618 0.1808 0.0356 0.0097 0.0713 0.1480

IMPERV_6.10 -0.0979 0.1072 0.0176 0.0727 0.0125 0.1114 -0.1217 -0.1011 0.0127 -0.0072

IMPERV_26.50 -0.0773 0.0341 -0.0227 0.0222 -0.0186 0.1342 -0.0499 -0.0889 -0.1318 -0.1651
46 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

of the end of the study period. AltFlows do, however, provide 

information on changes in the shifted rating from site visit to 

site visit, and it provides information on how that shifted rating changed throughout the range of observed flows.

All of the stability metrics that were developed and 

proposed through the course of this study are difficult to verify 

externally because there is no previous, widely accepted external definition of rating stability. To the extent that descriptive 

stability classes are valid, they serve as an external check on 

the other metrics. Since the metrics all compared imprecisely 

to the descriptive stability classes, which themselves were 

imprecise, they all are imprecise measurements of rating 

stability or flow record reliability. Other than that comparison, the metrics were selected in terms of correlation to each 

other, and those correlations were generally fairly weak. These 

stability metrics are probably appropriate to use to separate 

streamgages into general classes of Excellent, Good, Fair, and 

Poor, but small differences in a metric are unlikely to mean 

very much.

Descriptions from hydrographer interviews were essential for interpreting quantitative analyses. The survey in 

which hydrographers were asked to grade control stability on 

a numeric scale was weakened by differences in individual 

impressions about stability. The stability scores provided by 

the individual hydrographer who was familiar with the most 

streamgages were correlated more strongly with quantitative 

metrics than were the averaged scores. Inconsistent impressions about stability are unlikely to make a substantial difference in flow data computation but greatly complicate creating 

and interpreting a survey of hydrographers about controls 

conditions. The survey process might have been stronger had 

it been done as a round-table discussion among senior hydrographers and differences in perspective about sites that were 

rated differently by different people had been resolved. 

Future studies might consider attempting to separate 

individual ratings into parts representing section control, channel control, and overbank flow, and treating them separately. 

During the course of this study, exploratory analysis was done 

using dominant particle-size information captured during flow 

measurements. The analysis was less conclusive than seemed 

plausible. Quantitative measures of section control particle 

size might allow more conclusive analysis.

Summary

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

Virginia Department of Environmental Quality, has quantified several measures of rating stability and the frequency and 

magnitude of changes to ratings through time for 174 real-time 

continuous streamgages active in Virginia as of September 30, 

2013. The purpose of this report is to quantify the stability of 

stage-flow ratings in Virginia to help evaluate their reliability 

in providing real-time flow data. Relations between stage and 

flow from all flow measurements available at each site were 

determined. Mean daily flows for water years 1991–2013 

were compared to flows that would have been computed 

from the rating in effect when the previous flow measurement 

was made. 

Flow data computation procedures have changed substantially during water years 1991-2013. Timing of record 

computation is among the most critical of these changes. From 

1991 through 2001, the median number of days between the 

start date of the shift, the first date of data for which it was 

intended to modify, and the date it was created in the office 

by a hydrographer, fluctuated between about 240 and about 

300 days. The 75th percentile of days between start date and 

creation date of shifts was more than 365 for every year during 

that period. Beginning in 2002, in recognition of the growing importance to data users of near-real-time flow on the 

internet, a greater effort began to work records continuously. 

The median period between the start date of a shift and its 

final modification decreased by about 4 months from 2001 to 

2002. Only in 2012 and 2013 did one-half of the shifts have 

a delay between start date and final modification of about 60 

days, which is close to the 8-week interval between routine 

streamgage visits. 

Curves were fit through all available flow measurements 

for all the gages in Virginia’s real-time network as of September 30, 2013, that had at least 20 flow measurements with 

positive flow values. Generalized additive models (GAMs) 

were found to fit measurements better than LOESS curves. 

The GAM curves served as an average long-term rating. For 

each measurement with a positive flow value, residuals from 

the GAM curve were calculated. The residuals were plotted 

as a time series and by Julian date. The time-series plots were 

used to identify major changes to the control, and the measurements in the periods of equilibrium between major changes 

were assigned to rating families. At the 174 sites, 301 rating 

families were identified. At 107 of the sites, all measurements 

fit a single rating family. An additional 127 rating families 

were identified at the 67 sites where there were 2 or more rating families. Documented explanations were found for 67 of 

those 127 rating families. The most common reasons for the 

control to change enough to represent a new rating family are 

moving the gage (28 times), floods (26 times), and construction activities including bridge construction and removal, 

weir and control construction and removal, and channel or 

bed modifications (13 times). Provisional flow data from 

any streamgage that has recently experienced a major flood, 

regardless of historical stability, is more uncertain than usual 

until post-flood evidence emerges that the rating has remained 

stable or, if changed, is again well defined. 

A direct comparison between provisional flow data 

originally displayed on the web in near-real time and flow data 

approved for publication following subsequent flow measurements and review could not be made because provisional flow 

data have not been archived. As a substitute, alternative flow 

(AltFlow) tables were constructed for periods with complete 

records of shifts and ratings. Daily flows were acquired for 

these periods. Expanded shifted ratings were acquired for days 

during these periods when flow measurements were made. 
References Cited 47

Gage heights corresponding to mean daily flows were backcalculated and identified as belonging to measurement-tomeasurement periods. These gage heights were then related to 

two sets of ratings, those in effect when the measurement-tomeasurement period began (Qsame) and those in effect when the 

previous measurement-to-measurement period began (Qprev). 

Qsame was used instead of the actual published daily values to 

avoid rounding errors. Data availability varied by site, even 

for sites with complete flow record throughout water years 

1991–2013 because of differences among field offices in data 

archiving. Many sites with complete records of daily values 

for water years 1991–2013 had AltFlow records that began 

in 2002. 

Several metrics that summarized AltFlow tables were 

computed and evaluated with particular importance being 

given to how well they agreed with descriptive stability 

classes developed from hydrographer interviews. Of these 

stability metrics, four were determined to be meaningful and 

to represent different aspects of control stability that might 

be relevant to water managers. Total root mean square error 

(RMSE) between log-transformed Qprev and Qsame is affected by 

the magnitude and frequency of rating changes and the transformation weight changes throughout the range of flows so 

that high, medium, or low flows do not dominate the statistic. 

The number of days when the difference between Qprev and 

Qsame is freater than Qsame is a measure of relatively large rating 

changes, most of which come at low flow. The sum of absolute 

AltFlow error divided by total flow is a flow-weighted statistic 

that is strongly affected by large-magnitude rating changes, 

which are predominantly at the high end of the rating, and it 

is useful in evaluating rating stability relative to total volume 

of water in a period. Percentage of days with zero difference between Qprev and Qsame is a measure of the frequency of 

rating change. 

Three other meaningful metrics of control stability or 

provisional flow-data quality were computed. The coefficient 

of determination (R2) of GAMQ is computed from flow measurements, not rating changes. Because most of the scatter on 

the GAM models is at the low end of the plot, R2 of GAMQ is 

most sensitive to variability at the low end of ratings. Unlike 

the various AltFlow metrics, it is independent of time, and 

unlike most of them, its magnitude is independent of the flow 

magnitude of the individual error. Percentage of total estimated days and percentage of estimated days in the winter are 

weakly related to control stability, if they are related to it at 

all, but provide information on the overall quality of the flow 

record and on the likelihood that historical winter record was 

affected by ice.

Correlations among metrics varied, indicating they 

responded to different aspects of control stability. Correlations 

among most of the error terms derived from AltFlows were 

generally the strongest of the entire set. As an example, the 

magnitude of Spearman’s rho between AltFlow RMSE and 

5 of the other 6 such terms ranged from 0.75 to 0.90. The R2

of GAMQ was correlated with the four meaningful AltFlow 

stability metrics (Spearman’s rho absolute values ranging from 

0.5760 to 0.6960). 

The two candidate metrics that are based on percentages of estimates were strongly correlated to each other 

(rho = 0.8584). Both these metrics were weakly correlated 

with stability class, –0.2982 for total estimates and –0.1676 for 

winter estimates. Total estimates were moderately correlated 

with R2 of GAMQ and several of the AltFlow-derived metrics; 

the absolute value of rho was as high as 0.5200 with RMSE 

and greater than 0.4 for six of the other metrics. 

Stepwise multiple regression analysis was done to determine whether relations among the various stability metrics and 

quantitative basin and site characteristics could be determined. 

These relations were weak, and the regression models were 

not meaningful. Review of scatterplot and correlation matrices also indicated few strong correlations between stability 

terms and basin characteristics. Although quantitative relations 

between stability metrics and basin and site characteristics 

were all weak, some common patterns emerged. Streamgages 

on large streams (>500-squaremile drainage area) and at 

high elevations (>1,000 feet) were more likely to have stable 

controls and ratings than streamgages on small streams 

(<100-square mile drainage area) and at low elevations 

(<500 feet). Streamgages in western Virginia were more likely 

to have stable controls than were streamgages in northeastern 

Virginia, particularly small streams. There were exceptions to 

all three generalizations, and streamgages that were intermediate in those characteristics varied widely in stability. 

References Cited

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change in reservoir content data from selected stations in 

the lower Colorado River streamflow-gaging station network, 1995–99: U.S. Geological Survey Water-Resources 

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http://pubs.usgs.gov/wri/2001/4240/report.pdf.]

Austin, S.H., Krstolic, J.L., and Wiegand, Ute, 2011, Lowflow characteristics of Virginia streams: U.S. Geological 

Survey Scientific Investigations Report 2011–5143, 122 p., 

+ 9 tables on CD. [Also available at https://pubs.er.usgs.

gov/publication/sir20115143.]

Corbett, D.M., and others, 1943, Stream-gaging procedure—a 

manual describing methods and practices of the Geological 

Survey: U.S. Geological Survey Water-Supply Paper 888, 

245 p. [Also available at https://pubs.er.usgs.gov/publication/wsp888.]

Fenneman, N.M., and Johnson, D.W., 1946, Physical divisions 

of the United States: U.S. Geological Survey Physiography 

Committee Special Map, scale 1:7,000,000.
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Hayes, D.C., 1989, Low-flow characteristics of streams in Virginia: U.S. Geological Survey Water-Supply Paper 2374, 69 

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Helsel, D.R. and Hirsch, R.M. 2002, Statistical methods in 

water resources, USGS Techniques of Water Resources 

Investigations, book 4, chap. A3, 510 p.,accessed June 12, 

2018, http://water.usgs.gov/pubs/twri/twri4a3/.

Messinger, Terence, and Burgholzer, R.W., 2017, Ratings 

and estimated provisional streamflow for streamgages in 

Virginia, water years 1991 through 2013: U.S. Geological 

Survey data release, https://doi.org/10.5066/F72R3PXB.

Moss, M.E., and Gilroy, E.J., 1980, Cost-effective streamgaging strategies for the Lower Colorado River Basin: U.S. 

Geological Survey Open-File Report 80–1048, 111 p. [Also 

available at https://pubs.usgs.gov/of/1980/1048/report.pdf.]

Murphy, E.C., Hoyt, J.C., and Hollister, G.B., 1904, Hydrographic manual of the United States Geological Survey: 

U.S. Geological Survey Water Supply and Irrigation Paper 

94, 76 p. [Also available at https://pubs.usgs.gov/wsp/0094/

report.pdf.]

Nelms, D.L., Harlow, G.E., Jr., Plummer, L.N., and Busenberg, Eurybiades, 2003, Aquifer susceptibility in Virginia, 

1998–2000: U.S. Geological Survey Water-Resources 

Investigations Report 03–4278, 58 p., https://pubs.er.usgs.

gov/publication/wri034278.

Nelms, D.L., Harlow, G.E., Jr., and Hayes, D.C., 1997, Baseflow characteristics of streams in the Valley and Ridge, the 

Blue Ridge, and the Piedmont Physiographic Provinces of 

Virginia: U.S. Geological Survey Water-Supply Paper 2457, 

48 p., 1 pl. [Also available at https://pubs.usgs.gov/wsp/

wsp_2457/.]

R Core Team, 2014, R—a language and environment for 

statistical computing: Vienna, Austria, R Foundation for 

Statistical Computing, accessed September 2, 2016, at 

http://www.R-project.org/.

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

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

Geological Survey Water-Supply Paper 2175, 631 p. [Also 

available at https://pubs.usgs.gov/wsp/wsp2175/.]

Sauer, V.B., and Turnipseed, D.P., 2010, Stage measurement 

at gaging stations: U.S. Geological Survey Techniques and 

Methods book 3, chap. A7, 45 p. [Also available at http://

pubs.usgs.gov/tm/tm3-a7/.]

Turnipseed, D.P., and Sauer, V.B., 2010, Discharge measurements at gaging stations: U.S. Geological Survey Techniques and Methods book 3, chap. A8, 87 p. [Also available 

at http://pubs.usgs.gov/tm/tm3-a8/.]

U.S. Census Bureau, 2015, Cartographic boundary shapefiles—states, accessed November 15, 2017, at https://www.

census.gov/geo/maps-data/data/cbf/cbf_state.html.

U.S. Geological Survey, 1998, A new evaluation of the USGS 

streamgaging network—A report to Congress, 20 p., 

accessed November 15, 2017, at http://water.usgs.gov/

streamgaging/report.pdf. 

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two-million scale, accessed November 15, 2017, at http://

nationalmap.gov/.

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arc-second, accessed September 22, 2017, at http://viewer.

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usa/nwis/rt.

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https://waterdata.usgs.gov/va/nwis/wys_rpt/?site_

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stream-gaging program of the U.S. Geological Survey: U.S. 

Geological Survey Circular 1123, 22 p., accessed December 

22, 2016, at http://pubs.usgs.gov/circ/circ1123/overview.

html.

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generalized linear models: Journal of the Royal Statistical 

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January 7, 2014, at http://cran.r-project.org/web/packages/

mgcv/index.html.
Table 2 49

Streamgage 

number Streamgage name

Earliest date

Base rating Shift

01613900 Hogue Creek near Hayfield, VA 3/17/1999 9/20/2001

01615000 Opequon Creek near Berryville, VA 2/15/1984 11/30/1984

01616100 Dry Marsh Run near Berryville, VA 8/19/2002 8/20/2002

01620500 North River near Stokesville, VA 1/13/1998 8/21/2001

01621050 Muddy Creek at Mount Clinton, VA 9/30/1995 12/1/1996

01622000 North River near Burketown, VA 9/30/1997 8/3/2001

01625000 Middle River near Grottoes, VA 12/17/1982 9/30/1986

01626000 South River near Waynesboro, VA 3/19/1983 9/30/1986

01626850 South River near Dooms, VA 12/16/1982 4/17/1987

01627500 South River at Harriston, VA 1/8/1998 11/26/2000

01628500 South Fork Shenandoah River near Lynnwood, VA 12/17/1982 8/19/1985

01629500 South Fork Shenandoah River near Luray, VA 9/30/1999 8/2/2001

01631000 South Fork Shenandoah River at Front Royal, VA 11/5/1985 8/17/2001

01632000 North Fork Shenandoah River at Cootes Store, VA 9/6/1996 3/3/1997

01632082 Linville Creek at Broadway, VA 8/8/1985 8/23/1985

01632900 Smith Creek near New Market, VA 9/30/1983 8/21/1985

01633000 North Fork Shenandoah River at Mount Jackson, VA 3/18/1999 1/31/2001

01634000 North Fork Shenandoah River near Strasburg, VA 9/30/1984 9/30/1996

01634500 Cedar Creek near Winchester, VA 2/15/1984 9/27/1985

01635500 Passage Creek near Buckton, VA 2/26/1979 4/17/1987

01636316 Spout Run at Rt 621 near Millwood, VA 8/22/2002 9/5/2002

01636690 Piney Run near Lovettsville, VA 7/31/2001 9/27/2001

01638350 South Fork Catoctin Creek at Rt 698 near Waterford, VA 6/27/2001 7/4/2001

01638420 North Fork Catoctin Creek at Rt 681 near Waterford, VA 7/19/2001 7/19/2001

01638480 Catoctin Creek at Taylorstown, VA 11/7/1997 9/24/2001

01643590 Limestone Branch near Leesburg, VA 8/22/2001 8/22/2001

01643700 Goose Creek near Middleburg, VA 3/23/1991 6/15/2001

01643805 North Fork Goose Creek at Rt 729 near Lincoln, VA 7/18/2001 8/11/2001

01643880 Beaverdam Creek at Rt 734 near Mountville, VA 7/17/2001 7/17/2001

01644000 Goose Creek near Leesburg, VA 3/21/1998 11/28/2000

01644280 Broad Run near Leesburg, VA 9/1/2001 1/7/2002

01645704 Difficult Run above Fox Lake near Fairfax, VA 9/20/2007 9/20/2007

01645762 South Fork Little Difficult Run above Mouth near Vienna, VA 9/19/2007 9/19/2007

01646000 Difficult Run near Great Falls, VA 10/23/1983 9/10/1985

01646305 Dead Run at Whann Avenue near Mclean, VA 1/9/2008 1/9/2008

01652500 Fourmile Run at Alexandria, VA 9/30/1985 9/30/1998

01653000 Cameron Run at Alexandria, VA 9/30/1994 9/30/1996

0165389205 Accotink Creek near Ranger Road at Fairfax, VA 10/18/2011 10/29/2011

01654000 Accotink Creek near Annandale, VA 10/25/1997 9/30/2001

01656000 Cedar Run near Catlett, VA 5/4/1984 9/27/1985

01656903 Flatlick Branch above Frog Branch at Chantilly, VA 9/20/2007 9/20/2007

01658500 South Fork Quantico Creek near Independent Hill, VA 9/30/1995 10/19/1996

01660400 Aquia Creek near Garrisonville, VA 1/19/1996 11/3/1999

01662800 Battle Run near Laurel Mills, VA 2/15/1984 10/20/1984

01663500 Hazel River at Rixeyville, VA 9/12/2001 10/19/2001

Table 2. Earliest dates for base ratings and shifts in the Virginia node of the National Water Information System database for 

streamgages active as of September 30, 2013.

[VA, Virginia; Rt, Route]
50 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

Table 2. Earliest dates for base ratings and shifts in the Virginia node of the National Water Information System database for 

streamgages active as of September 30, 2013.—Continued

[VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name

Earliest date

Base rating Shift

01664000 Rappahannock River at Remington, VA 1/9/1998 9/30/2001

01665500 Rapidan River near Ruckersville, VA 6/27/1995 9/30/1998

01666500 Robinson River near Locust Dale, VA 9/30/1982 9/30/1984

01667500 Rapidan River near Culpeper, VA 3/15/1999 1/26/2001

01668000 Rappahannock River near Fredericksburg, VA 9/30/1980 9/8/1999

01669000 Piscataway Creek near Tappahannock, VA 5/2/2001 9/18/2001

01669520 Dragon Swamp at Mascot, VA 2/4/1998 3/24/2001

01670400 North Anna River near Partlow, VA 9/30/1982 9/30/1984

01671020 North Anna River at Hart Corner near Doswell, VA 3/8/1989 7/29/1998

01671025 North Anna River above Little River near Doswell, VA 6/29/2004 6/29/2004

01671100 Little River near Doswell, VA 2/5/1998 6/8/2001

01672500 South Anna River near Ashland, VA 10/14/1982 11/25/1996

01673000 Pamunkey River near Hanover, VA 11/28/1993 1/28/1997

01673550 Totopotomoy Creek near Studley, VA 3/26/1984 9/28/1985

01673800 Po River near Spotsylvania, VA 3/30/1984 8/21/1985

01674000 Mattaponi River near Bowling Green, VA 10/25/1982 10/16/1984

01674500 Mattaponi River near Beulahville, VA 8/29/1989 8/24/1995

02011400 Jackson River near Bacova, VA 9/30/1991 9/30/1994

02011460 Back Creek near Sunrise, VA 1/8/1998 6/5/2001

02011470 Back Creek at Sunrise, VA 10/23/1984 9/30/1994

02011490 Little Back Creek near Sunrise, VA 9/30/1984 9/30/2002

02011500 Back Creek near Mountain Grove, VA 9/30/1993 9/30/1994

02011800 Jackson River below Gathright Dam near Hot Spgs, VA 1/29/1994 9/30/1994

02013000 Dunlap Creek near Covington, VA 1/20/1988 6/30/1995

02013100 Jackson River below Dunlap Creek at Covington, VA 9/30/1981 6/27/1995

02014000 Potts Creek near Covington, VA 12/5/1993 1/15/1995

02015700 Bullpasture River at Williamsville, VA 1/19/1996 7/21/1998

02016000 Cowpasture River near Clifton Forge, VA 9/30/1992 11/4/1999

02016500 James River at Lick Run, VA 9/30/1992 3/21/1998

02017500 Johns Creek at New Castle, VA 12/5/1993 9/24/2001

02018000 Craig Creek at Parr, VA 12/6/1993 9/30/2001

02018500 Catawba Creek near Catawba, VA 2/17/1998 9/24/2001

02019500 James River at Buchanan, VA 9/30/1995 4/20/1998

02020500 Calfpasture River above Mill Creek at Goshen, VA 9/30/1998 10/15/1998

02021500 Maury River at Rockbridge Baths, VA 9/30/1984 12/2/1996

02022500 Kerrs Creek near Lexington, VA 3/21/2000 3/21/2001

02024000 Maury River near Buena Vista, VA 9/30/1992 9/30/1999

02024752 James River at Blue Ridge Pkwy near Big Island, VA 6/7/2005 9/1/2006

02024915 Pedlar River at Forest Road near Buena Vista, VA 11/5/2002 11/7/2002

02025500 James River at Holcomb Rock, VA 9/30/1990 10/9/1998

02026000 James River at Bent Creek, VA 9/30/1981 7/31/2001

02027000 Tye River near Lovingston, VA 1/8/1998 10/8/1998

02027500 Piney River at Piney River, VA 4/29/1999 3/21/2001

02028500 Rockfish River near Greenfield, VA 12/5/1993 7/16/1998

02029000 James River at Scottsville, VA 9/30/1979 11/10/1996
Table 2 51

Table 2. Earliest dates for base ratings and shifts in the Virginia node of the National Water Information System database for 

streamgages active as of September 30, 2013.—Continued

[VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name

Earliest date

Base rating Shift

02030000 Hardware River below Briery Run near Scottsville, VA 9/30/1989 9/10/1997

02030500 Slate River near Arvonia, VA 9/30/1980 10/29/1984

02031000 Mechums River near White Hall, VA 2/23/1994 9/17/2001

02032250 Moormans River near Free Union, VA 11/3/1985 7/6/2005

02032640 North Fork Rivanna River near Earlysville, VA 9/30/1993 9/30/1993

02034000 Rivanna River at Palmyra, VA 1/24/1999 3/30/2001

02035000 James River at Cartersville, VA 11/6/1985 7/29/1986

02036500 Fine Creek at Fine Creek Mills, VA 11/26/1983 10/2/1984

02037000 James River And Kanawha Canal near Richmond, VA 9/30/1993 3/29/2001

02037500 James River near Richmond, VA 10/9/1996 9/30/1997

02038850 Holiday Creek near Andersonville, VA 9/30/1999 6/5/2001

02039000 Buffalo Creek near Hampden Sydney, VA 12/17/1982 9/30/1984

02039500 Appomattox River at Farmville, VA 9/30/1987 3/22/2001

02040000 Appomattox River at Mattoax, VA 11/7/1985 11/6/1985

02040892 Appomattox River at Route 602 near Mannboro, VA 6/21/2011 6/21/2011

02041000 Deep Creek near Mannboro, VA 11/27/1983 10/2/1984

02041650 Appomattox River at Matoaca, VA 12/3/1993 6/17/2000

02042500 Chickahominy River near Providence Forge, VA 9/30/1993 12/9/1996

02044500 Nottoway River near Rawlings, VA 4/18/2000 6/5/2001

02045500 Nottoway River near Stony Creek, VA 9/30/1984 10/2/1984

02046000 Stony Creek near Dinwiddie, VA 3/22/2001 9/26/2001

02047000 Nottoway River near Sebrell, VA 2/9/1998 9/30/2000

02047500 Blackwater River near Dendron, VA 2/21/1982 10/1/1984

02049500 Blackwater River near Franklin, VA 10/6/1981 5/3/1997

02051000 North Meherrin River near Lunenburg, VA 2/4/1998 2/4/1998

02051500 Meherrin River near Lawrenceville, VA 9/30/1980 10/2/1996

02052000 Meherrin River at Emporia, VA 1/16/1998 6/8/2001

02053800 South Fork Roanoke River near Shawsville, VA 4/11/1983 9/30/1984

02054500 Roanoke River at Lafayette, VA 4/18/2000 1/20/2001

02054530 Roanoke River at Glenvar, VA 12/11/1991 1/4/1992

02055000 Roanoke River at Roanoke, VA 3/29/1994 8/20/2000

02055100 Tinker Creek near Daleville, VA 9/30/1993 9/30/1996

02056000 Roanoke River at Niagara, VA 9/30/1992 1/24/2001

02056650 Back Creek near Dundee, VA 9/30/1999 9/30/2001

02056900 Blackwater River near Rocky Mount, VA 1/15/1995 3/30/2001

02058400 Pigg River near Sandy Level, VA 9/7/1987 9/8/1997

02059485 Goose Creek at Rt 747 near Bunker Hill, VA 9/29/2006 9/15/2007

02059500 Goose Creek near Huddleston, VA 9/30/1995 10/14/2001

02060500 Roanoke River at Altavista, VA 11/5/1985 9/26/1988

02061000 Big Otter River near Bedford, VA 12/10/2006 8/5/2007

02061500 Big Otter River near Evington, VA 12/5/1993 6/6/2001

02062500 Roanoke (Staunton) River at Brookneal, VA 9/30/1992 10/3/1995

02064000 Falling River near Naruna, VA 2/15/1984 5/25/1985

02065500 Cub Creek at Phenix, VA 11/28/1993 10/8/1998

02066000 Roanoke (Staunton) River at Randolph, VA 8/18/1985 6/24/1995
52 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

Table 2. Earliest dates for base ratings and shifts in the Virginia node of the National Water Information System database for 

streamgages active as of September 30, 2013.—Continued

[VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name

Earliest date

Base rating Shift

02069700 South Mayo River near Nettleridge, VA 3/20/2000 3/20/2001

02070000 North Mayo River near Spencer, VA 12/5/1993 9/25/2001

02071530 Smith River at Smith Riv Church near Woolwine, VA 10/20/1994 7/29/1997

02072000 Smith River near Philpott, VA 6/10/1981 10/7/1997

02072500 Smith River at Bassett, VA 9/30/1985 9/30/1995

02073000 Smith River at Martinsville, VA 3/28/1994 12/6/2001

02074500 Sandy River near Danville, VA 1/5/1982 6/29/1985

02075045 Dan River at Stp near Danville, VA 9/30/1993 10/7/1996

02075500 Dan River at Paces, VA 11/2/1981 10/3/1995

02077000 Banister River at Halifax, VA 10/18/1981 1/4/1985

02077500 Hyco River near Denniston, VA 9/30/1984 10/5/1996

02079640 Allen Creek near Boydton, VA 3/7/1984 5/25/1985

03164000 New River near Galax, VA 9/30/1991 8/25/1994

03165000 Chestnut Creek at Galax, VA 9/30/1985 9/30/1996

03165500 New River at Ivanhoe, VA 12/2/1996 9/30/1997

03167000 Reed Creek at Grahams Forge, VA 6/5/1992 1/20/2001

03168000 New River at Allisonia, VA 11/24/1992 9/30/1994

03170000 Little River at Graysontown, VA 9/30/1991 9/30/2000

03171000 New River at Radford, VA 9/30/1989 9/30/1994

03173000 Walker Creek at Bane, VA 3/25/1993 9/30/1994

03175500 Wolf Creek near Narrows, VA 11/5/1985 9/30/1994

03176500 New River at Glen Lyn, VA 3/25/1993 9/30/1994

03177710 Bluestone River at Falls Mills, VA 3/24/1993 8/25/1993

03207800 Levisa Fork at Big Rock, VA 1/25/1984 9/30/1994

03208500 Russell Fork at Haysi, VA 2/1/1985 9/30/1994

03208950 Cranes Nest River near Clintwood, VA 4/4/1977 9/30/1988

03209000 Pound River below Flannagan Dam, near Haysi, VA 12/2/1985 9/30/1994

03471500 South Fork Holston River at Riverside, near Chilhowie, VA 12/24/1992 9/30/1996

03473000 South Fork Holston River near Damascus, VA 2/11/1994 9/30/1996

03474000 Middle Fork Holston River at Seven Mile Ford, VA 10/9/1976 9/30/1996

03475000 Middle Fork Holston River near Meadowview, VA 1/4/1992 9/30/1996

03478400 Beaver Creek at Bristol, VA 9/30/1991 9/30/1996

03488000 North Fork Holston River near Saltville, VA 1/13/1989 9/30/1996

03490000 North Fork Holston River near Gate City, VA 3/31/2012 12/27/2012

03524000 Clinch River at Cleveland, VA 12/24/1992 10/2/1995

03524500 Guest River at Coeburn, VA 8/1/2012 4/20/2013

03527000 Clinch River at Speers Ferry, VA 9/30/2001 10/3/2001

03529500 Powell River at Big Stone Gap, VA 9/30/2001 10/3/2001

03531500 Powell River near Jonesville, VA 9/30/1994 9/30/1995
Table 3 53

Table 3. Number of unique shifts recorded in the National Water Information System at streamgages in Virginia active as of September 30, 2013; includes multiple shifts begun on the same day.[--, no shifts because data are unavailable for the period; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name

Number of unique shifts

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

Total

01613900 Hogue Creek near Hayfield, VA -- -- -- -- -- -- -- -- -- -- -- 14 16 9 20 6 3 10 6 24 5 2 18 14 14701615000 Opequon Creek near Berryville, VA 5 14 21 5 12 13 8 19 - - - - - 1 6 6 3 8 12 5 16 17 16 11 19801616100 Dry Marsh Run near Berryville, VA -- -- -- -- -- -- -- -- -- -- -- -- 3 6 5 7 10 6 10 12 10 12 9 11 10101620500 North River near Stokesville, VA -- -- -- -- -- -- -- -- -- -- -- 4 2 6 5 12 5 7 10 9 7 16 18 16 11701621050 Muddy Creek at Mount Clinton, VA -- -- -- -- -- -- 2 11 9 8 15 15 18 6 6 5 8 9 9 14 10 11 10 13 17901622000 North River near Burketown, VA -- -- -- -- -- -- -- -- -- -- -- 5 13 4 6 3 2 12 8 6 5 1 9 8 8201625000 Middle River near Grottoes, VA 6 10 7 9 7 10 7 7 10 10 9 11 13 6 8 3 4 4 10 3 2 2 9 5 17201626000 South River near Waynesboro, VA 7 6 9 8 12 3 9 5 13 24 17 11 10 4 5 3 2 13 9 7 2 1 14 7 20101626850 South River near Dooms, VA 4 6 4 5 0 4 4 1 - - - - - - - 3 4 13 29 10 5 2 21 11 12601627500 South River at Harriston, VA -- -- -- -- -- -- -- -- -- -- 1 15 14 6 12 5 1 9 13 5 3 3 9 12 10801628500 South Fork Shenandoah River near Lynnwood, VA 4 9 8 10 5 15 9 7 12 18 10 11 13 3 16 7 6 7 8 3 5 1 9 7 20301629500 South Fork Shenandoah River near Luray, VA -- -- -- -- -- -- -- -- -- -- -- 4 13 8 12 6 0 6 9 3 9 0 11 5 8601631000 South Fork Shenandoah River at Front Royal, VA -- -- -- -- -- -- -- -- -- -- -- 5 10 5 4 7 5 6 9 9 13 7 15 12 10701632000 North Fork Shenandoah River at Cootes Store, VA -- -- -- -- -- -- -- 2 3 1 6 6 4 7 11 14 6 11 8 12 11 8 7 7 12401632082 Linville Creek at Broadway, VA 8 14 14 12 18 24 11 13 5 9 11 22 7 14 6 2 6 9 11 7 5 5 10 9 25201632900 Smith Creek near New Market, VA 2 8 10 13 5 16 13 12 12 13 13 7 27 16 6 7 16 8 12 11 26 13 16 11 29301633000 North Fork Shenandoah River at Mount Jackson, VA -- -- -- -- -- -- -- -- -- -- -- 18 16 6 4 6 3 3 9 9 2 3 11 10 10001634000 North Fork Shenandoah River near Strasburg, VA -- -- -- -- -- -- 1 4 9 10 9 9 7 0 9 6 6 5 12 9 13 12 14 8 14301634500 Cedar Creek near Winchester, VA 8 33 9 19 17 20 10 13 19 11 19 6 6 6 6 10 4 6 13 6 12 2 11 8 27401635500 Passage Creek near Buckton, VA 3 14 8 9 2 4 8 6 8 8 12 4 6 12 8 3 3 6 4 2 1 2 10 6 14901636316 Spout Run at Rt 621 near Millwood, VA -- -- -- -- -- -- -- -- -- -- -- -- 3 4 9 9 6 5 12 11 11 9 7 10 9601636690 Piney Run near Lovettsville, VA -- -- -- -- -- -- -- -- -- -- -- 4 7 8 5 9 3 8 6 13 9 14 19 13 11801638350 South Fork Catoctin Creek at Rt 698 near Waterford, VA -- -- -- -- -- -- -- -- -- -- -- 4 4 11 3 6 9 2 14 16 12 14 14 6 11501638420 North Fork Catoctin Creek at Rt 681 near Waterford, VA -- -- -- -- -- -- -- -- -- -- -- 12 6 7 3 6 4 7 12 15 13 11 12 18 12601638480 Catoctin Creek at Taylorstown, VA -- -- -- -- -- -- -- -- -- -- -- 4 11 7 10 10 10 21 19 3 1 3 11 10 12001643590 Limestone Branch near Leesburg, VA -- -- -- -- -- -- -- -- -- -- -- 1 4 8 3 6 8 9 11 13 9 12 18 31 13301643700 Goose Creek near Middleburg, VA -- -- -- -- -- -- -- -- -- -- -- 6 5 3 2 10 8 3 14 13 10 17 13 11 11501643805 North Fork Goose Creek at Rt 729 near Lincoln, VA -- -- -- -- -- -- -- -- -- -- -- 4 14 10 7 6 5 5 10 14 21 14 15 13 13801643880 Beaverdam Creek at Rt 734 near Mountville, VA -- -- -- -- -- -- -- -- -- -- -- 6 5 13 7 5 5 7 17 13 15 13 23 14 14301644000 Goose Creek near Leesburg, VA -- -- -- -- -- -- -- -- -- -- 1 33 24 5 8 6 17 31 14 10 3 8 13 6 17901644280 Broad Run near Leesburg, VA -- -- -- -- -- -- -- -- -- -- -- -- 5 0 3 4 6 7 11 12 9 14 14 7 9201645704 Difficult Run above Fox Lake near Fairfax, VA -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 3 13 10 6 12 8 11 6301645762 South Fork Little Difficult Run above Mouth near Vienna, VA -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 7 15 13 17 17 30 14 11301646000 Difficult Run near Great Falls, VA 12 8 10 19 14 22 3 15 30 12 12 18 4 6 4 9 1 13 2 3 3 6 10 10 24601646305 Dead Run at Whann Avenue near Mclean, VA -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 11 17 21 18 55 33 15501652500 Fourmile Run at Alexandria, VA -- -- -- -- -- -- -- -- 5 10 18 17 8 10 7 9 10 8 9 16 13 10 18 14 18201653000 Cameron Run at Alexandria, VA -- -- -- -- -- -- 1 2 4 10 16 15 9 16 8 8 11 2 7 11 6 14 18 9 167

0165389205 Accotink Creek near Ranger Road at Fairfax, VA -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 4 37 20 61

01654000 Accotink Creek near Annandale, VA -- -- -- -- -- -- -- -- -- -- -- 8 32 8 6 11 3 7 18 8 17 8 19 7 15201656000 Cedar Run near Catlett, VA 5 15 11 21 17 15 12 21 27 20 9 12 8 10 4 3 2 15 7 8 7 4 10 7 270
54 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013 Table 3. Number of unique shifts recorded in the National Water Information System at streamgages in Virginia active as of September 30, 2013; includes multiple shifts begun on the same day.—Continued [--, no shifts because data are unavailable for the period; VA, Virginia; Rt, Route] Streamgage number Streamgage name Number of unique shifts

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

Total

01656903 Flatlick Branch above Frog Branch at Chantilly, VA -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 9 10 14 10 15 31 18 10701658500 South Fork Quantico Creek near Independent Hill, VA -- -- -- -- -- -- 6 23 8 15 17 21 10 10 28 8 11 19 6 13 15 22 50 20 30201660400 Aquia Creek near Garrisonville, VA -- -- -- -- -- -- -- -- -- 3 11 17 7 9 10 6 13 8 7 9 14 18 9 12 15301662800 Battle Run near Laurel Mills, VA 6 27 14 28 16 25 - 2 13 5 9 11 11 10 12 5 6 15 5 12 4 4 11 8 25901663500 Hazel River at Rixeyville, VA -- -- -- -- -- -- -- -- -- -- -- 8 11 2 1 8 3 11 14 8 9 6 14 6 10101664000 Rappahannock River at Remington, VA -- -- -- -- -- -- -- -- -- -- -- 4 7 3 0 3 3 20 12 5 11 13 16 8 10501665500 Rapidan River near Ruckersville, VA -- -- -- -- -- -- -- -- 3 6 5 9 8 12 12 14 0 20 9 7 4 4 15 10 13801666500 Robinson River near Locust Dale, VA 9 11 14 14 3 17 11 7 18 12 6 10 6 14 6 19 8 9 12 7 9 6 15 15 25801667500 Rapidan River near Culpeper, VA -- -- -- -- -- -- -- -- -- -- -- 15 15 14 4 10 4 11 6 6 6 3 13 11 11801668000 Rappahannock River near Fredericksburg, VA -- -- -- -- -- -- -- -- -- 1 8 2 6 3 6 5 2 8 7 10 8 16 14 9 10501669000 Piscataway Creek near Tappahannock, VA -- -- -- -- -- -- -- -- -- -- -- 4 18 12 12 11 5 5 12 10 8 7 14 11 12901669520 Dragon Swamp at Mascot, VA -- -- -- -- -- -- -- -- -- -- -- 8 13 7 1 7 5 8 10 6 7 6 9 5 9201670400 North Anna River near Partlow, VA 10 104 37 10 8 7 - - - - - - - - - - - 7 9 5 7 13 15 9 24101671020 North Anna River at Hart Corner near Doswell, VA -- -- -- -- -- -- -- -- 5 4 10 5 8 14 7 7 5 9 9 7 6 4 14 7 12101671025 North Anna River above Little River near Doswell, VA -- -- -- -- -- -- -- -- -- -- -- -- -- -- 1 6 5 4 11 10 10 10 33 12 102

01671100 Little River near Doswell, VA -- -- -- -- -- -- -- -- -- -- -- 22 18 11 4 44 4 10 7 5 5 9 12 6 157

01672500 South Anna River near Ashland, VA -- -- -- -- -- -- 3 4 - - - - - 3 1 1 2 3 5 11 13 11 13 9 7901673000 Pamunkey River near Hanover, VA -- -- -- -- -- -- -- 8 12 12 6 9 4 10 4 3 9 3 8 5 13 7 14 5 13201673550 Totopotomoy Creek near Studley, VA 3 9 -- 12 11 5 12 9 14 13 8 10 15 8 6 13 21 10 6 3 10 8 13 8 22701673800 Po River near Spotsylvania, VA 6 10 11 17 11 18 13 13 17 16 10 53 15 8 5 12 6 17 2 8 7 4 15 9 30301674000 Mattaponi River near Bowling Green, VA 12 13 11 18 10 12 8 20 19 18 13 17 8 10 12 24 1 6 5 4 3 3 17 9 27301674500 Mattaponi River near Beulahville, VA -- -- -- -- -- 3 9 8 7 15 11 8 11 6 6 5 5 5 2 6 8 12 13 6 146

02011400 Jackson River near Bacova, VA -- -- -- -- 1 4 6 5 6 9 6 10 7 0 2 5 2 3 6 6 2 4 4 1 8902011460 Back Creek near Sunrise, VA -- -- -- -- -- -- -- -- -- -- -- 4 6 3 3 5 4 7 9 5 7 11 6 7 7702011470 Back Creek at Sunrise, VA -- -- -- -- 1 3 16 8 0 0 8 5 1 1 0 4 1 2 5 6 5 8 8 6 8802011490 Little Back Creek near Sunrise, VA -- -- -- -- -- -- -- -- -- -- -- -- 1 0 1 0 0 3 3 0 3 3 0 0 1402011500 Back Creek near Mountain Grove, VA -- -- -- -- 1 7 12 8 28 14 10 5 4 4 2 4 2 6 6 8 9 9 12 4 15502011800 Jackson River below Gathright Dam near Hot Spgs, VA -- -- -- -- 1 3 6 6 2 0 0 2 3 0 0 0 0 1 0 1 0 7 4 2 38

02013000 Dunlap Creek near Covington, VA -- -- -- -- -- 3 15 7 13 12 8 18 16 7 2 6 5 8 7 8 7 10 15 6 17302013100 Jackson River below Dunlap Creek at Covington, VA -- -- -- -- -- 3 0 0 4 15 7 7 9 4 4 8 4 5 5 4 6 7 10 0 10202014000 Potts Creek near Covington, VA -- -- -- -- -- 3 10 4 9 10 10 11 7 5 4 6 5 7 6 8 9 12 12 4 14202015700 Bullpasture River at Williamsville, VA -- -- -- -- -- -- -- -- 8 16 8 3 9 2 8 6 4 4 1 2 3 3 5 5 8702016000 Cowpasture River near Clifton Forge, VA -- -- -- -- -- -- -- -- -- 2 1 8 8 1 3 1 0 4 5 2 6 4 0 2 4702016500 James River at Lick Run, VA -- -- -- -- -- -- -- -- 2 6 4 5 9 4 2 4 2 5 1 3 6 3 5 4 6502017500 Johns Creek at New Castle, VA -- -- -- -- -- -- -- -- -- -- -- 6 11 7 9 8 6 3 3 4 2 2 13 10 8402018000 Craig Creek at Parr, VA -- -- -- -- -- -- -- -- -- -- -- 5 3 2 7 6 3 7 8 8 7 11 0 4 7102018500 Catawba Creek near Catawba, VA -- -- -- -- -- -- -- -- -- -- -- 12 26 13 15 8 8 10 14 9 3 4 11 10 14302019500 James River at Buchanan, VA -- -- -- -- -- -- -- -- 2 4 14 0 10 0 0 0 0 0 0 4 3 0 11 1 4902020500 Calfpasture River above Mill Creek at Goshen, VA -- -- -- -- -- -- -- -- 2 13 0 6 10 4 7 5 8 8 5 10 4 5 12 7 10602021500 Maury River at Rockbridge Baths, VA -- -- -- -- -- -- 2 2 4 12 6 7 2 7 2 3 4 3 6 9 9 9 11 4 102
Table 3 55

Table 3. Number of unique shifts recorded in the National Water Information System at streamgages in Virginia active as of September 30, 2013; includes multiple shifts begun on the same day.—Continued[--, no shifts because data are unavailable for the period; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name

Number of unique shifts

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

Total

02022500 Kerrs Creek near Lexington, VA -- -- -- -- -- -- -- -- -- -- -- 34 14 6 8 9 8 7 6 5 5 2 15 11 13002024000 Maury River near Buena Vista, VA -- -- -- -- -- -- -- -- -- 1 5 9 6 3 2 2 6 2 6 2 7 10 5 2 6802024752 James River at Blue Ridge Pkwy near Big Island, VA -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 5 7 7 5 3 1 8 10 4602024915 Pedlar River at Forest Road near Buena Vista, VA -- -- -- -- -- -- -- -- -- -- -- -- 3 0 3 4 5 15 4 2 3 2 16 8 6502025500 James River at Holcomb Rock, VA -- -- -- -- -- -- -- -- 1 4 2 4 3 2 2 10 3 7 10 7 9 6 9 10 8902026000 James River at Bent Creek, VA -- -- -- -- -- -- -- -- -- -- -- 5 4 1 2 6 2 5 7 9 9 4 7 11 7202027000 Tye River near Lovingston, VA -- -- -- -- -- -- -- -- 3 4 14 4 11 3 4 4 3 6 6 3 2 3 14 7 9102027500 Piney River at Piney River, VA -- -- -- -- -- -- -- -- -- -- -- 11 10 6 8 4 7 13 4 2 5 6 15 9 10002028500 Rockfish River near Greenfield, VA -- -- -- -- -- -- -- -- 5 6 7 18 8 12 6 2 6 15 4 6 2 4 12 10 12302029000 James River at Scottsville, VA -- -- -- -- -- -- 2 4 4 6 4 7 3 0 2 5 6 6 9 5 6 10 14 5 9802030000 Hardware River below Briery Run near Scottsville, VA -- -- -- -- -- -- -- 6 6 8 13 16 48 28 10 8 4 9 2 2 6 6 11 7 19002030500 Slate River near Arvonia, VA 12 19 14 14 8 14 - - - - - - - - - 1 6 12 13 6 2 4 16 7 14802031000 Mechums River near White Hall, VA -- -- -- -- -- -- -- -- -- -- -- 8 22 6 14 9 7 20 7 9 5 4 12 6 12902032250 Moormans River near Free Union, VA -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 7 6 19 6 3 10 5 13 13 8202032640 North Fork Rivanna River near Earlysville, VA -- -- -- 1 11 19 9 2 2 25 10 17 11 9 10 6 6 11 30 8 14 6 17 8 23202034000 Rivanna River at Palmyra, VA -- -- -- -- -- -- -- -- -- -- -- 10 9 5 6 8 9 5 9 6 9 2 13 10 10102035000 James River at Cartersville, VA 2 2 -- 6 4 4 -- 1 -- -- -- 5 10 6 1 3 4 6 11 5 10 10 16 9 11502036500 Fine Creek at Fine Creek Mills, VA 14 27 21 24 17 13 12 20 14 27 18 20 31 10 8 26 15 14 15 16 10 8 19 5 40402037000 James River And Kanawha Canal near Richmond, VA -- -- -- -- -- -- -- -- -- -- -- 31 24 49 16 50 21 11 21 14 13 8 11 19 28802037500 James River near Richmond, VA -- -- -- -- -- -- -- 1 -- 4 4 0 8 0 2 8 3 4 4 3 5 2 6 2 5602038850 Holiday Creek near Andersonville, VA -- -- -- -- -- -- -- -- -- -- -- 8 9 3 5 6 11 8 9 14 10 13 11 13 12002039000 Buffalo Creek near Hampden Sydney, VA 7 31 15 23 16 14 16 13 12 8 9 18 8 11 15 12 9 7 9 4 4 1 16 9 28702039500 Appomattox River at Farmville, VA -- -- -- -- -- -- -- -- -- -- -- 24 27 6 8 10 9 5 5 5 5 4 14 10 13202040000 Appomattox River at Mattoax, VA 4 12 20 8 3 21 -- 11 14 10 21 10 8 12 6 7 4 4 4 4 3 4 18 8 21602040892 Appomattox River at Route 602 near Mannboro, VA -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 12 19 9 4002041000 Deep Creek near Mannboro, VA 21 33 21 18 6 13 21 10 13 13 15 9 11 5 8 6 5 9 7 6 3 3 12 5 27302041650 Appomattox River at Matoaca, VA -- -- -- -- -- -- -- -- -- -- 8 8 17 3 0 10 8 12 12 7 5 3 6 8 10702042500 Chickahominy River near Providence Forge, VA -- -- -- -- -- -- 1 19 8 12 8 27 8 3 1 3 9 2 6 4 10 9 11 7 14802044500 Nottoway River near Rawlings, VA -- -- -- -- -- -- -- -- -- -- -- 21 44 2 8 9 3 18 13 4 11 10 14 10 16702045500 Nottoway River near Stony Creek, VA 4 18 12 10 11 18 12 16 17 4 14 9 16 14 19 14 6 11 3 4 4 8 15 8 26702046000 Stony Creek near Dinwiddie, VA -- -- -- -- -- -- -- -- -- -- -- 13 34 8 10 30 15 18 14 16 11 2 15 9 19502047000 Nottoway River near Sebrell, VA -- -- -- -- -- -- -- -- -- -- 1 3 12 10 2 4 2 2 8 7 6 10 10 11 8802047500 Blackwater River near Dendron, VA 6 14 12 8 7 11 10 4 8 20 14 5 12 8 8 8 8 6 3 10 2 7 9 7 20702049500 Blackwater River near Franklin, VA -- -- -- -- -- -- -- 1 10 14 12 5 4 6 4 1 2 2 2 8 6 10 14 13 11402051000 North Meherrin River near Lunenburg, VA -- -- -- -- -- -- -- -- 8 8 14 27 12 10 4 7 6 19 6 2 7 5 16 5 15602051500 Meherrin River near Lawrenceville, VA -- -- -- -- -- -- 2 5 4 8 6 8 4 5 3 3 2 6 7 10 8 12 12 6 11102052000 Meherrin River at Emporia, VA -- -- -- -- -- -- -- -- -- -- -- 8 16 14 10 11 6 3 1 4 1 1 12 5 9202053800 South Fork Roanoke River near Shawsville, VA 8 10 9 27 9 14 5 18 22 3 9 9 10 12 9 9 9 10 4 5 2 2 12 10 23702054500 Roanoke River at Lafayette, VA -- -- -- -- -- -- -- -- -- -- -- 12 6 6 6 8 11 9 5 2 6 4 14 11 10002054530 Roanoke River at Glenvar, VA -- -- 4 4 9 2 6 11 5 8 6 8 4 8 11 5 4 6 2 4 3 1 8 12 131
56 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013 Table 3. Number of unique shifts recorded in the National Water Information System at streamgages in Virginia active as of September 30, 2013; includes multiple shifts begun on the same day.—Continued [--, no shifts because data are unavailable for the period; VA, Virginia; Rt, Route] Streamgage number Streamgage name Number of unique shifts

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

Total

02055000 Roanoke River at Roanoke, VA -- -- -- -- -- -- -- -- -- -- 3 7 13 0 3 1 2 6 7 3 12 10 5 2 7402055100 Tinker Creek near Daleville, VA -- -- -- -- -- -- 1 5 15 20 10 15 14 9 7 10 6 9 9 7 9 8 6 1 16102056000 Roanoke River at Niagara, VA -- -- -- -- -- -- -- -- -- -- -- 5 11 1 3 3 0 7 2 1 0 1 0 0 3402056650 Back Creek near Dundee, VA -- -- -- -- -- -- -- -- -- -- -- 6 4 0 4 4 1 15 15 4 5 5 14 9 8602056900 Blackwater River near Rocky Mount, VA -- -- -- -- -- -- -- -- -- -- -- 12 17 0 4 11 3 7 4 2 1 1 9 9 8002058400 Pigg River near Sandy Level, VA -- -- -- -- -- -- -- 3 -- 4 12 6 4 4 2 6 5 6 6 10 12 11 10 13 11402059485 Goose Creek at Rt 747 near Bunker Hill, VA -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 2 6 13 1 9 15 5 5102059500 Goose Creek near Huddleston, VA -- -- -- -- -- -- -- -- -- -- -- 3 9 9 8 6 13 11 22 9 6 3 13 8 12002060500 Roanoke River at Altavista, VA -- -- -- -- -- 1 7 6 5 3 5 8 2 1 1 7 2 3 1 4 5 7 8 13 8902061000 Big Otter River near Bedford, VA -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 7 2 4 4 12 10 8 4702061500 Big Otter River near Evington, VA -- -- -- -- -- -- -- -- -- -- -- 15 15 6 4 8 13 9 7 4 5 4 11 10 11102062500 Roanoke (Staunton) River at Brookneal, VA -- -- -- -- -- 3 8 1 6 18 8 12 13 3 3 5 6 2 6 5 6 11 12 7 13502064000 Falling River near Naruna, VA 16 6 18 6 7 12 24 11 19 12 17 28 18 6 10 16 8 6 6 6 5 4 14 10 28502065500 Cub Creek at Phenix, VA -- -- -- -- -- -- -- -- 2 10 12 11 15 8 6 13 10 12 12 12 8 8 12 10 16102066000 Roanoke (Staunton) River at Randolph, VA -- -- -- -- -- 3 9 4 5 5 9 12 8 0 3 2 4 1 7 5 8 7 10 7 10902069700 South Mayo River near Nettleridge, VA -- -- -- -- -- -- -- -- -- -- -- 8 9 10 4 11 4 2 1 2 1 2 8 6 6802070000 North Mayo River near Spencer, VA -- -- -- -- -- -- -- -- -- -- -- 9 9 0 4 4 8 1 1 2 3 2 12 7 6202071530 Smith River at Smith Riv Church near Woolwine, VA -- -- -- -- -- -- -- 5 6 6 9 16 11 5 8 17 8 3 5 4 2 4 9 9 12702072000 Smith River near Philpott, VA -- -- -- -- -- -- -- 1 3 4 5 15 14 3 3 1 3 7 7 8 5 2 14 5 10002072500 Smith River at Bassett, VA -- -- -- -- -- 3 2 2 5 2 4 9 2 1 1 5 2 6 8 7 3 6 15 5 8802073000 Smith River at Martinsville, VA -- -- -- -- -- -- -- -- -- -- -- 1 8 11 12 6 7 6 8 6 8 4 7 4 8802074500 Sandy River near Danville, VA 3 30 12 19 12 27 9 13 4 8 9 9 15 8 4 12 6 4 5 9 5 5 15 14 25702075045 Dan River at Stp near Danville, VA -- -- -- -- -- -- 1 0 5 6 6 5 2 5 3 8 2 3 8 5 10 10 6 8 9302075500 Dan River at Paces, VA -- -- -- -- -- 5 4 3 3 4 7 8 4 6 1 5 3 5 3 6 6 7 6 7 9302077000 Banister River at Halifax, VA -- -- 7 1 6 7 5 1 0 0 1 6 4 2 0 4 3 1 3 5 4 4 13 14 9102077500 Hyco River near Denniston, VA -- -- -- -- -- -- 1 9 8 20 20 15 10 5 1 6 7 9 2 7 6 9 10 13 15802079640 Allen Creek near Boydton, VA 7 26 21 13 19 28 20 - - 2 8 16 12 12 6 19 15 16 14 10 19 18 17 18 33603164000 New River near Galax, VA -- -- -- -- 2 17 5 11 7 12 13 8 7 4 3 4 2 6 6 5 5 3 11 4 13503165000 Chestnut Creek at Galax, VA -- -- -- -- -- -- 5 10 15 13 8 12 6 5 5 3 4 9 14 8 8 7 5 2 13903165500 New River at Ivanhoe, VA -- -- -- -- -- -- -- 1 3 6 6 8 15 4 4 4 6 10 6 7 6 2 6 3 9703167000 Reed Creek at Grahams Forge, VA -- -- -- -- -- -- -- -- -- -- -- 7 9 5 5 3 2 6 7 5 5 6 6 0 6603168000 New River at Allisonia, VA -- -- -- -- 3 0 4 0 0 0 5 9 4 1 0 0 3 6 3 4 3 4 6 1 5603170000 Little River at Graysontown, VA -- -- -- -- -- -- -- -- -- -- 1 4 14 7 10 7 6 10 9 5 2 3 9 4 9103171000 New River at Radford, VA -- -- -- -- 1 4 0 2 7 9 9 12 10 4 2 2 1 7 3 2 1 0 0 5 8103173000 Walker Creek at Bane, VA -- -- -- -- 1 0 5 9 4 9 12 11 11 7 4 4 2 5 7 6 5 4 7 7 12003175500 Wolf Creek near Narrows, VA -- -- -- -- 4 18 5 7 19 20 15 12 13 4 4 7 5 6 4 5 3 5 7 3 16603176500 New River at Glen Lyn, VA -- -- -- -- 1 11 14 5 18 8 4 0 6 0 1 0 3 7 1 5 9 3 5 5 10603177710 Bluestone River at Falls Mills, VA -- -- -- 8 4 7 10 5 - - - - - - 4 16 0 9 6 8 7 9 6 2 10103207800 Levisa Fork at Big Rock, VA -- -- -- -- 1 9 12 6 5 4 4 13 11 5 6 6 6 5 6 5 7 10 10 3 13403208500 Russell Fork at Haysi, VA -- -- -- -- 3 16 10 6 10 8 10 12 9 6 6 3 8 4 8 3 7 3 3 5 140
Table 3 57

Table 3. Number of unique shifts recorded in the National Water Information System at streamgages in Virginia active as of September 30, 2013; includes multiple shifts begun on the same day.—Continued[--, no shifts because data are unavailable for the period; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name

Number of unique shifts

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

Total

03208950 Cranes Nest River near Clintwood, VA -- -- -- -- 4 16 8 9 12 9 54 14 16 6 5 6 2 8 11 8 15 14 17 5 23903209000 Pound River below Flannagan Dam, near Haysi, VA -- -- -- -- 1 6 -- 10 7 10 9 9 12 2 1 6 9 7 6 6 5 6 5 5 12203471500 South Fork Holston River at Riverside, near Chilhowie, VA -- -- -- -- -- -- 1 6 8 13 6 3 11 7 3 9 6 6 9 13 10 4 2 3 12003473000 South Fork Holston River near Damascus, VA -- -- -- -- -- -- 1 3 9 8 10 13 7 6 3 2 4 4 3 3 1 5 4 5 9103474000 Middle Fork Holston River at Seven Mile Ford, VA -- -- -- -- -- -- 1 8 10 4 11 11 14 4 5 8 5 3 6 7 8 8 8 1 12203475000 Middle Fork Holston River near Meadowview, VA -- -- -- -- -- -- 3 8 8 13 12 9 10 5 5 6 2 5 7 2 5 6 5 1 11203478400 Beaver Creek at Bristol, VA -- -- -- -- -- -- 3 4 15 12 9 15 8 6 5 4 4 5 9 5 6 4 18 4 13603488000 North Fork Holston River near Saltville, VA -- -- -- -- -- -- 1 4 12 15 11 9 6 11 2 9 3 6 9 6 9 7 10 4 13403490000 North Fork Holston River near Gate City, VA -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 1 1 203524000 Clinch River at Cleveland, VA -- -- -- -- -- 3 8 3 0 12 11 7 7 0 3 4 5 6 10 3 10 7 8 5 11203524500 Guest River at Coeburn, VA -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 3 303527000 Clinch River at Speers Ferry, VA -- -- -- -- -- -- -- -- -- -- -- 2 4 0 4 7 3 3 4 3 1 3 1 5 4003529500 Powell River at Big Stone Gap, VA -- -- -- -- -- -- -- -- -- -- -- 2 11 5 6 4 5 7 9 6 10 7 8 7 8703531500 Powell River near Jonesville, VA -- -- -- -- -- 1 10 10 10 14 6 11 4 4 4 6 1 6 7 5 2 7 5 2 115

Total 214 539 384 419 342 599 520 605 783 913 959 1,559 1,635 996 899 1,183 880 1,294 1,345 1,186 1,194 1,190 2,081 1,407 23,126
58 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

Table 4. Number of base ratings and number of days they were in effect for streamgages in Virginia, water years 1991–2013, for 

periods when the ratings were stored in the National Water Information System.

[VA, Virginia; Rt, Route]

Streamgage

number Streamgage name Number of base ratings available

Number of days 

those ratings 

were in effect

Average days 

per rating

01613900 Hogue Creek near Hayfield, VA 2 5,312 2,656

01615000 Opequon Creek near Berryville, VA 9 6,594 733

01616100 Dry Marsh Run near Berryville, VA 1 4,061 4,061

01620500 North River near Stokesville, VA 6 5,741 957

01621050 Muddy Creek at Mount Clinton, VA 4 6,576 1,644

01622000 North River near Burketown, VA 1 5,845 5,845

01625000 Middle River near Grottoes, VA 3 8,402 2,801

01626000 South River near Waynesboro, VA 2 8,402 4,201

01626850 South River near Dooms, VA 6 5,257 876

01627500 South River at Harriston, VA 2 5,745 2,873

01628500 South Fork Shenandoah River near Lynnwood, VA 2 8,402 4,201

01629500 South Fork Shenandoah River near Luray, VA 4 5,115 1,279

01631000 South Fork Shenandoah River at Front Royal, VA 3 8,402 2,801

01632000 North Fork Shenandoah River at Cootes Store, VA 7 6,234 891

01632082 Linville Creek at Broadway, VA 4 8,402 2,101

01632900 Smith Creek near New Market, VA 6 8,402 1,400

01633000 North Fork Shenandoah River at Mount Jackson, VA 1 5,312 5,312

01634000 North Fork Shenandoah River near Strasburg, VA 4 8,402 2,101

01634500 Cedar Creek near Winchester, VA 3 8,402 2,801

01635500 Passage Creek near Buckton, VA 2 8,402 4,201

01636316 Spout Run at Rt 621 near Millwood, VA 2 4,059 2,029

01636690 Piney Run near Lovettsville, VA 4 4,445 1,111

01638350 South Fork Catoctin Creek at Rt 698 near Waterford, VA 4 4,480 1,120

01638420 North Fork Catoctin Creek at Rt 681 near Waterford, VA 4 4,457 1,114

01638480 Catoctin Creek at Taylorstown, VA 2 5,807 2,904

01643590 Limestone Branch near Leesburg, VA 4 4,424 1,106

01643700 Goose Creek near Middleburg, VA 8 6,616 827

01643805 North Fork Goose Creek at Rt 729 near Lincoln, VA 6 4,458 743

01643880 Beaverdam Creek at Rt 734 near Mountville, VA 9 4,460 496

01644000 Goose Creek near Leesburg, VA 2 5,673 2,837

01644280 Broad Run near Leesburg, VA 6 4,414 736

01645704 Difficult Run above Fox Lake near Fairfax, VA 4 2,203 551

01645762 South Fork Little Difficult Run above Mouth near Vienna, VA 5 2,204 441

01646000 Difficult Run near Great Falls, VA 6 8,402 1,400

01646305 Dead Run at Whann Avenue near Mclean, VA 3 2,092 697

01652500 Fourmile Run at Alexandria, VA 4 8,402 2,101

01653000 Cameron Run at Alexandria, VA 5 6,941 1,388

0165389205 Accotink Creek near Ranger Road at Fairfax, VA 2 714 357

01654000 Accotink Creek near Annandale, VA 4 5,821 1,455

01656000 Cedar Run near Catlett, VA 5 8,402 1,680

01656903 Flatlick Branch above Frog Branch at Chantilly, VA 5 2,204 441

01658500 South Fork Quantico Creek near Independent Hill, VA 4 6,576 1,644

01660400 Aquia Creek near Garrisonville, VA 4 5,716 1,429

01662800 Battle Run near Laurel Mills, VA 7 7,588 1,084

01663500 Hazel River at Rixeyville, VA 6 4,402 734
Table 4 59

Table 4. Number of base ratings and number of days they were in effect for streamgages in Virginia, water years 1991–2013, for 

periods when the ratings were stored in the National Water Information System.—Continued

[VA, Virginia; Rt, Route]

Streamgage

number Streamgage name Number of base ratings available

Number of days 

those ratings 

were in effect

Average days 

per rating

01664000 Rappahannock River at Remington, VA 3 5,745 1,915

01665500 Rapidan River near Ruckersville, VA 4 5,483 1,371

01666500 Robinson River near Locust Dale, VA 2 8,402 4,201

01667500 Rapidan River near Culpeper, VA 1 5,314 5,314

01668000 Rappahannock River near Fredericksburg, VA 5 8,402 1,680

01669000 Piscataway Creek near Tappahannock, VA 2 4,536 2,268

01669520 Dragon Swamp at Mascot, VA 2 5,718 2,859

01670400 North Anna River near Partlow, VA 5 4,206 841

01671020 North Anna River at Hart Corner near Doswell, VA 5 8,402 1,680

01671025 North Anna River above Little River near Doswell, VA 2 3,381 1,691

01671100 Little River near Doswell, VA 1 5,359 5,359

01672500 South Anna River near Ashland, VA 4 6,305 1,576

01673000 Pamunkey River near Hanover, VA 6 7,248 1,208

01673550 Totopotomoy Creek near Studley, VA 8 8,402 1,050

01673800 Po River near Spotsylvania, VA 5 8,402 1,680

01674000 Mattaponi River near Bowling Green, VA 4 8,402 2,101

01674500 Mattaponi River near Beulahville, VA 4 8,402 2,101

02011400 Jackson River near Bacova, VA 2 8,037 4,019

02011460 Back Creek near Sunrise, VA 6 5,746 958

02011470 Back Creek at Sunrise, VA 8 8,402 1,050

02011490 Little Back Creek near Sunrise, VA 4 8,402 2,101

02011500 Back Creek near Mountain Grove, VA 3 7,306 2,435

02011800 Jackson River below Gathright Dam near Hot Spgs, VA 4 7,185 1,796

02013000 Dunlap Creek near Covington, VA 4 8,402 2,101

02013100 Jackson River below Dunlap Creek at Covington, VA 4 8,402 2,101

02014000 Potts Creek near Covington, VA 4 7,241 1,810

02015700 Bullpasture River at Williamsville, VA 2 6,466 3,233

02016000 Cowpasture River near Clifton Forge, VA 5 7,671 1,534

02016500 James River at Lick Run, VA 2 7,671 3,836

02017500 Johns Creek at New Castle, VA 1 7,241 7,241

02018000 Craig Creek at Parr, VA 3 7,240 2,413

02018500 Catawba Creek near Catawba, VA 2 5,706 2,853

02019500 James River at Buchanan, VA 2 6,576 3,288

02020500 Calfpasture River above Mill Creek at Goshen, VA 4 5,480 1,370

02021500 Maury River at Rockbridge Baths, VA 3 8,402 2,801

02022500 Kerrs Creek near Lexington, VA 1 4,943 4,943

02024000 Maury River near Buena Vista, VA 3 7,671 2,557

02024752 James River at Blue Ridge Pkwy near Big Island, VA 3 3,038 1,013

02024915 Pedlar River at Forest Road near Buena Vista, VA 5 3,984 797

02025500 James River at Holcomb Rock, VA 4 8,402 2,101

02026000 James River at Bent Creek, VA 5 8,402 1,680

02027000 Tye River near Lovingston, VA 5 5,746 1,149

02027500 Piney River at Piney River, VA 3 5,270 1,757

02028500 Rockfish River near Greenfield, VA 3 7,241 2,414

02029000 James River at Scottsville, VA 3 8,402 2,801
60 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

Table 4. Number of base ratings and number of days they were in effect for streamgages in Virginia, water years 1991–2013, for 

periods when the ratings were stored in the National Water Information System.—Continued

[VA, Virginia; Rt, Route]

Streamgage

number Streamgage name Number of base ratings available

Number of days 

those ratings 

were in effect

Average days 

per rating

02030000 Hardware River below Briery Run near Scottsville, VA 3 8,045 2,682

02030500 Slate River near Arvonia, VA 2 4,863 2,432

02031000 Mechums River near White Hall, VA 2 7,160 3,580

02032250 Moormans River near Free Union, VA 5 5,565 1,113

02032640 North Fork Rivanna River near Earlysville, VA 4 7,306 1,827

02034000 Rivanna River at Palmyra, VA 2 5,364 2,682

02035000 James River at Cartersville, VA 2 8,402 4,201

02036500 Fine Creek at Fine Creek Mills, VA 5 8,402 1,680

02037000 James River And Kanawha Canal near Richmond, VA 3 7,306 2,435

02037500 James River near Richmond, VA 4 6,202 1,550

02038850 Holiday Creek near Andersonville, VA 3 5,115 1,705

02039000 Buffalo Creek near Hampden Sydney, VA 4 8,402 2,101

02039500 Appomattox River at Farmville, VA 1 4,384 4,384

02040000 Appomattox River at Mattoax, VA 4 8,402 2,101

02040892 Appomattox River at Route 602 near Mannboro, VA 2 833 417

02041000 Deep Creek near Mannboro, VA 6 8,402 1,400

02041650 Appomattox River at Matoaca, VA 3 7,243 2,414

02042500 Chickahominy River near Providence Forge, VA 8 7,306 913

02044500 Nottoway River near Rawlings, VA 1 4,915 4,915

02045500 Nottoway River near Stony Creek, VA 7 7,569 1,081

02046000 Stony Creek near Dinwiddie, VA 2 4,577 2,288

02047000 Nottoway River near Sebrell, VA 6 5,714 952

02047500 Blackwater River near Dendron, VA 6 8,402 1,400

02049500 Blackwater River near Franklin, VA 9 8,402 934

02051000 North Meherrin River near Lunenburg, VA 3 5,719 1,906

02051500 Meherrin River near Lawrenceville, VA 3 8,402 2,801

02052000 Meherrin River at Emporia, VA 3 5,738 1,913

02053800 South Fork Roanoke River near Shawsville, VA 7 8,402 1,200

02054500 Roanoke River at Lafayette, VA 2 4,915 2,457

02054530 Roanoke River at Glenvar, VA 2 7,965 3,983

02055000 Roanoke River at Roanoke, VA 3 7,127 2,376

02055100 Tinker Creek near Daleville, VA 2 7,306 3,653

02056000 Roanoke River at Niagara, VA 2 7,671 3,836

02056650 Back Creek near Dundee, VA 3 5,115 1,705

02056900 Blackwater River near Rocky Mount, VA 2 6,835 3,417

02058400 Pigg River near Sandy Level, VA 4 8,402 2,101

02059485 Goose Creek at Rt 747 near Bunker Hill, VA 4 2,559 640

02059500 Goose Creek near Huddleston, VA 2 6,576 3,288

02060500 Roanoke River at Altavista, VA 3 8,402 2,801

02061000 Big Otter River near Bedford, VA 3 2,488 829

02061500 Big Otter River near Evington, VA 2 7,240 3,620

02062500 Roanoke (Staunton) River at Brookneal, VA 4 7,671 1,918

02064000 Falling River near Naruna, VA 5 8,402 1,680

02065500 Cub Creek at Phenix, VA 1 7,247 7,247

02066000 Roanoke (Staunton) River at Randolph, VA 2 8,402 4,201
Table 4 61

Table 4. Number of base ratings and number of days they were in effect for streamgages in Virginia, water years 1991–2013, for 

periods when the ratings were stored in the National Water Information System.—Continued

[VA, Virginia; Rt, Route]

Streamgage

number Streamgage name Number of base ratings available

Number of days 

those ratings 

were in effect

Average days 

per rating

02069700 South Mayo River near Nettleridge, VA 1 4,943 4,943

02070000 North Mayo River near Spencer, VA 1 7,241 7,241

02071530 Smith River at Smith Riv Church near Woolwine, VA 6 6,922 1,154

02072000 Smith River near Philpott, VA 4 8,402 2,101

02072500 Smith River at Bassett, VA 6 8,402 1,400

02073000 Smith River at Martinsville, VA 2 7,128 3,564

02074500 Sandy River near Danville, VA 2 8,402 4,201

02075045 Dan River at Stp near Danville, VA 5 7,306 1,461

02075500 Dan River at Paces, VA 1 2,876 2,876

02077000 Banister River at Halifax, VA 5 8,290 1,658

02077500 Hyco River near Denniston, VA 5 5,840 1,168

02079640 Allen Creek near Boydton, VA 5 6,960 1,392

03164000 New River near Galax, VA 4 8,037 2,009

03165000 Chestnut Creek at Galax, VA 3 8,402 2,801

03165500 New River at Ivanhoe, VA 5 6,148 1,230

03167000 Reed Creek at Grahams Forge, VA 2 7,789 3,894

03168000 New River at Allisonia, VA 2 7,617 3,808

03170000 Little River at Graysontown, VA 4 8,037 2,009

03171000 New River at Radford, VA 2 8,402 4,201

03173000 Walker Creek at Bane, VA 6 7,496 1,249

03175500 Wolf Creek near Narrows, VA 3 8,035 2,678

03176500 New River at Glen Lyn, VA 4 7,496 1,874

03177710 Bluestone River at Falls Mills, VA 5 4,792 958

03207800 Levisa Fork at Big Rock, VA 6 8,402 1,400

03208500 Russell Fork at Haysi, VA 4 8,402 2,101

03208950 Cranes Nest River near Clintwood, VA 5 8,402 1,680

03209000 Pound River below Flannagan Dam, near Haysi, VA 4 8,402 2,101

03471500 South Fork Holston River at Riverside, near Chilhowie, VA 3 7,587 2,529

03473000 South Fork Holston River near Damascus, VA 5 7,173 1,435

03474000 Middle Fork Holston River at Seven Mile Ford, VA 1 8,402 8,402

03475000 Middle Fork Holston River near Meadowview, VA 2 7,942 3,971

03478400 Beaver Creek at Bristol, VA 5 8,037 1,607

03488000 North Fork Holston River near Saltville, VA 3 8,402 2,801

03490000 North Fork Holston River near Gate City, VA 1 549 549

03524000 Clinch River at Cleveland, VA 3 7,587 2,529

03524500 Guest River at Coeburn, VA 2 427 214

03527000 Clinch River at Speers Ferry, VA 6 4,384 731

03529500 Powell River at Big Stone Gap, VA 3 4,384 1,461

03531500 Powell River near Jonesville, VA 3 6,941 2,314

Total 643 1,140,402 1,774
62 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013 Table 9. Rating families, dates they were in effect, variability statistics, and explanations for their causes for streamgages active in Virginia in October 2013.—Continued [GAM, generalized additive model; R2, coefficient of determination; RatFam, rating family; VA, Virginia; Rt, Route; Italicized text represents rating families that ended before the primary study period, water years 1991–2013] Streamgage number Streamgage name Rating family Used in multisite analysis? First measurement Final or most recent measurement Number of measurements Spearman’s rho

R2 of GAM 

of gage 

height as a 

function of 

flow

R2 of GAM 

of flow as 

a function 

of gage 

height

Explanation

01613900 Hogue Creek near Hayfield, VA 01613900_RF1 No 10/6/1980 4/14/2009 185 0.8426 0.8581 0.8575 First RatFam at site

01613900_RF2 Yes 6/2/2009 9/4/2013 29 0.7824 0.7881 0.7949 Backwater from rock pile

01615000 Opequon Creek near Berryville, VA 01615000_RF1 No 10/16/1940 12/2/1997 525 0.8069 0.8768 0.7990 First RatFam at site

01615000_RF2 Yes 10/15/2002 10/22/2013 86 0.9094 0.3266 0.8446 Moved gage

01616100 Dry Marsh Run near Berryville, VA 01616100_RF1 Yes 8/21/2002 10/21/2013 83 0.9267 0.9080 0.9009 First RatFam at site01620500 North River near Stokesville, VA 01620500_RF1 No 12/4/1945 5/14/1958 163 0.7013 0.5888 0.6009 First RatFam at site

01620500_RF2 No 6/10/1958 10/24/1985 268 0.9278 0.7488 0.7725 Moved gage and changed datum01620500_RF3 No 11/5/1985 4/18/1996 83 0.8386 0.5657 0.6338 Moved gage and changed datum01620500_RF4 Yes 6/3/1996 10/24/2013 133 0.5819 0.2853 0.2875 Moved gage and changed datum

01621050 Muddy Creek at Mount Clinton, VA 01621050_RF1 Yes 1/28/1993 10/24/2013 204 0.9295 0.9622 0.8750 First RatFam at site01622000 North River near Burketown, VA 01622000_RF1 No 6/1/1926 8/24/1938 48 0.9971 0.9983 0.9956 First RatFam at site

01622000_RF2 Yes 10/26/1938 9/3/2013 567 0.9763 0.9886 0.9760 Moved gage

01625000 Middle River near Grottoes, VA 01625000_RF1 No 2/18/1925 1/18/1966 330 0.9888 0.9938 0.9902 First RatFam at site

01625000_RF2 Yes 5/24/1966 9/18/2013 370 0.8753 0.8948 0.8422 Graphical appearance

01626000 South River near Waynesboro, VA 01626000_RF1 Yes 11/17/1981 9/18/2013 227 0.9825 0.9943 0.9819 First RatFam at site01626850 South River near Dooms, VA 01626850_RF1 No 4/17/1974 9/30/1985 122 0.9372 0.9682 0.9564 First RatFam at site

01626850_RF2 No 1/10/1986 10/11/1996 90 0.9509 0.9896 0.9706 Control changed by November 1985 flood01626850_RF3 Yes 7/20/2005 9/18/2013 73 0.9197 0.9669 0.9390 Data gap

01627500 South River at Harriston, VA 01627500_RF1 Yes 2/16/1925 9/18/2013 442 0.7833 0.8581 0.8174 First RatFam at site01628500 South Fork Shenandoah River near Lynnwood, VA 01628500_RF1 Yes 9/18/1930 10/24/2013 616 0.9891 0.9938 0.9862 First RatFam at site01629500 South Fork Shenandoah River near Luray, VA 01629500_RF1 Yes 4/26/1925 10/22/2013 393 0.9460 0.9607 0.9436 First RatFam at site01631000 South Fork Shenandoah River at Front Royal, VA 01631000_RF1 Yes 7/12/1930 10/22/2013 665 0.9697 0.9785 0.9697 First RatFam at site01632000 North Fork Shenandoah River at Cootes Store, VA 01632000_RF1 No 2/28/1925 2/6/1942 81 0.9605 0.9750 0.9155 First RatFam at site

01632000_RF2 No 3/13/1942 7/30/1946 63 0.8557 0.8676 0.8236 Apparent attempt to build a rock dam/control01632000_RF3 No 8/8/1946 2/25/1960 136 0.9579 0.9420 0.9202 Concrete weir installed01632000_RF4 No 4/5/1960 10/25/1985 207 0.9979 0.9970 0.9946 Graphical appearance01632000_RF5 No 2/3/1986 7/31/1996 78 0.9685 0.9613 0.9145 Control changed by November 1985 flood01632000_RF6 Yes 9/6/1996 10/23/2013 119 0.9165 0.9578 0.8601 Control changed by September 1996 flood

01632082 Linville Creek at Broadway, VA 01632082_RF1 No 8/9/1985 1/17/1996 100 0.8740 0.9482 0.9055 First RatFam at site

01632082_RF2 Yes 1/19/1996 9/3/2013 136 0.9459 0.9842 0.9631 Control changed by January 1996 flood

01632900 Smith Creek near New Market, VA 01632900_RF1 No 8/19/1960 7/8/1963 47 0.9602 0.9784 0.9717 First RatFam at site

01632900_RF2 Yes 8/2/1963 10/23/2013 413 0.8754 0.9359 0.8589 Moved gage

01633000 North Fork Shenandoah River at Mount Jackson, VA 01633000_RF1 Yes 1/11/1989 10/22/2013 180 0.9932 0.9964 0.9895 First RatFam at site01634000 North Fork Shenandoah River near Strasburg, VA 01634000_RF1 No 3/6/1925 10/17/1942 93 0.9925 0.9985 0.9945 First RatFam at site

01634000_RF2 Yes 11/5/1942 10/23/2013 580 0.9854 0.9916 0.9822 Control changed by October 1942 flood

01634500 Cedar Creek near Winchester, VA 01634500_RF1 Yes 10/15/1942 10/22/2013 198 0.9691 0.9895 0.9696 First RatFam at site01635500 Passage Creek near Buckton, VA 01635500_RF1 Yes 10/15/1942 10/22/2013 173 0.9873 0.9895 0.9844 First RatFam at site01636316 Spout Run at Rt 621 near Millwood, VA 01636316_RF1 Yes 8/22/2002 10/21/2013 84 0.8416 0.9267 0.8619 First RatFam at site01636690 Piney Run near Lovettsville, VA 01636690_RF1 Yes 8/2/2001 11/6/2013 89 0.9242 0.9204 0.8676 First RatFam at site01638350 South Fork Catoctin Creek at Rt 698 near Waterford, VA 01638350_RF1 Yes 8/2/2001 11/6/2013 92 0.9217 0.9433 0.8937 First RatFam at site01638420 North Fork Catoctin Creek at Rt 681 near Waterford, VA 01638420_RF1 Yes 8/2/2001 11/6/2013 88 0.9750 0.9837 0.9473 First RatFam at site01638480 Catoctin Creek at Taylorstown, VA 01638480_RF1 No 8/4/1971 9/27/1983 120 0.9643 0.9710 0.9565 First RatFam at site

01638480_RF2 Yes 11/3/1983 8/21/2013 251 0.9290 0.9658 0.8529 Moved gage and changed datum

01643590 Limestone Branch near Leesburg, VA 01643590_RF1 Yes 9/6/2001 11/6/2013 94 0.9721 0.9889 0.9761 First RatFam at site01643700 Goose Creek near Middleburg, VA 01643700_RF1 Yes 2/2/1970 11/7/2013 176 0.9793 0.9873 0.9407 First RatFam at site01643805 North Fork Goose Creek at Rt 729 near Lincoln, VA 01643805_RF1 Yes 8/2/2001 11/7/2013 95 0.9438 0.9717 0.8952 First RatFam at site01643880 Beaverdam Creek at Rt 734 near Mountville, VA 01643880_RF1 Yes 8/2/2001 11/7/2013 90 0.9358 0.9495 0.8339 First RatFam at site
Table 9 63

Table 9. Rating families, dates they were in effect, variability statistics, and explanations for their causes for streamgages active in Virginia in October 2013.—Continued[GAM, generalized additive model; R2, coefficient of determination; RatFam, rating family; VA, Virginia; Rt, Route; Italicized text represents rating families that ended before the primary study period, water years 1991–2013]

Streamgage 

number Streamgage name Rating family

Used in 

multisite 

analysis?

First 

measurement

Final or 

most recent 

measurement

Number of 

measurements

Spearman’s 

rho

R2 of GAM 

of gage 

height as a 

function of 

flow

R2 of GAM 

of flow as 

a function 

of gage 

height

Explanation

01644000 Goose Creek near Leesburg, VA 01644000_RF1 No 1/21/1930 9/15/1938 42 0.9767 0.9927 0.9764 First RatFam at site

01644000_RF2 No 2/4/1939 8/3/1970 350 0.9787 0.9665 0.9385 Moved gage and changed datum01644000_RF3 No 9/12/1977 10/5/1982 47 0.9537 0.9863 0.9408 Data gap01644000_RF4 Yes 11/16/1988 10/22/2013 198 0.9892 0.9781 0.9480 Data gap

01644280 Broad Run near Leesburg, VA 01644280_RF1 Yes 11/30/2001 11/5/2013 87 0.9507 0.9295 0.9421 First RatFam at site01645704 Difficult Run above Fox Lake near Fairfax, VA 01645704_RF1 Yes 9/27/2007 9/17/2013 61 0.9334 0.9843 0.9530 First RatFam at site01645762 South Fork Little Difficult Run above Mouth near Vienna, 

VA

01645762_RF1 No 9/27/2007 8/30/2011 41 0.8447 0.8906 0.8599 First RatFam at site01645762_RF2 Yes 9/12/2011 9/18/2013 19 0.9377 0.9771 0.9932 Control changed by flood

01646000 Difficult Run near Great Falls, VA 01646000_RF1 Yes 2/12/1935 9/17/2013 714 0.9827 0.9839 0.9729 First RatFam at site01646305 Dead Run at Whann Avenue near Mclean, VA 01646305_RF1 Yes 1/9/2008 9/17/2013 56 0.7886 0.9232 0.8711 First RatFam at site01652500 Fourmile Run at Alexandria, VA 01652500_RF1 No 6/6/1951 8/20/1973 130 0.7795 0.8480 0.8947 First RatFam at site

01652500_RF2 Yes 10/29/1990 9/16/2013 125 0.7080 0.3223 0.8181 Moved gage

01653000 Cameron Run at Alexandria, VA 01653000_RF1 No 6/24/1955 11/4/1975 324 0.4209 0.5222 0.5683 First RatFam at site

01653000_RF2 No 11/9/1976 3/7/1979 27 0.8102 0.1581 0.9233 Moved gage01653000_RF3 No 11/8/1979 6/21/1983 30 0.8272 0.2117 0.8418 Moved gage back to original location and changed 

datum

01653000_RF4 No 1/3/1984 2/27/1986 22 0.3524 0.1458 0.4205 Graphical appearance01653000_RF5 Yes 3/27/1986 9/16/2013 251 0.6614 0.6311 0.6664 Data gap

0165389205Accotink Creek near Ranger Road at Fairfax, VA 0165389205_

RF1

Yes 10/19/2011 9/17/2013 23 0.9842 0.9960 0.9924 First RatFam at site

01654000 Accotink Creek near Annandale, VA 01654000_RF1 No 11/25/1943 4/29/1970 283 0.8504 0.9478 0.8690 First RatFam at site

01654000_RF2 No 6/4/1970 7/3/1975 60 0.9298 0.9862 0.9601 Moved gage01654000_RF3 No 8/7/1975 12/12/1977 25 0.9906 0.9993 0.9908 Graphical appearance01654000_RF4 Yes 1/30/1978 9/16/2013 297 0.7315 0.8313 0.6026 Graphical appearance

01656000 Cedar Run near Catlett, VA 01656000_RF1 Yes 12/4/1950 9/5/2013 196 0.9754 0.9887 0.9374 First RatFam at site01656903 Flatlick Branch above Frog Branch at Chantilly, VA 01656903_RF1 Yes 9/27/2007 9/18/2013 63 0.9857 0.9964 0.9872 First RatFam at site01658500 South Fork Quantico Creek near Independent Hill, VA 01658500_RF1 No 5/1/1951 10/26/1988 372 0.8521 0.9160 0.7401 First RatFam at site

01658500_RF2 Yes 1/24/1990 11/5/2013 219 0.8986 0.9372 0.8486 Control changed by flood

01660400 Aquia Creek near Garrisonville, VA 01660400_RF1 No 8/30/1971 10/16/1997 235 0.6973 0.6948 0.5426 First RatFam at site

01660400_RF2 Yes 12/1/1997 11/5/2013 124 0.9236 0.5582 0.4969 Data gap/hiatus

01662800 Battle Run near Laurel Mills, VA 01662800_RF1 No 9/2/1958 6/12/1995 406 0.7945 0.8302 0.7207 First RatFam at site

01662800_RF2 Yes 10/3/1997 9/19/2013 117 0.9893 0.5851 0.6708 Moved gage

01663500 Hazel River at Rixeyville, VA 01663500_RF1 Yes 7/27/1942 11/4/2013 543 0.9797 0.9786 0.9180 First RatFam at site01664000 Rappahannock River at Remington, VA 01664000_RF1 Yes 12/15/1942 11/4/2013 601 0.9869 0.9905 0.9626 First RatFam at site01665500 Rapidan River near Ruckersville, VA 01665500_RF1 No 8/31/1989 5/24/1995 55 0.7228 0.8717 0.6584 First RatFam at site

01665500_RF2 Yes 9/2/1998 10/30/2013 127 0.9868 0.9837 0.9549 Moved gage

01666500 Robinson River near Locust Dale, VA 01666500_RF1 Yes 6/8/1984 9/19/2013 208 0.9764 0.9551 0.9470 First RatFam at site01667500 Rapidan River near Culpeper, VA 01667500_RF1 Yes 10/16/1942 9/19/2013 201 0.9920 0.9819 0.9864 First RatFam at site01668000 Rappahannock River near Fredericksburg, VA 01668000_RF1 No 9/12/1907 10/24/2000 557 0.9937 0.9926 0.9901 First RatFam at site

01668000_RF2 Yes 12/18/2000 10/22/2013 81 0.9741 0.9761 0.9568 Moved gage

01669000 Piscataway Creek near Tappahannock, VA 01669000_RF1 No 6/8/1951 4/7/1999 407 0.7667 0.5727 0.5808 First RatFam at site

01669000_RF2 No 6/11/1999 2/1/2005 50 0.8205 0.5075 0.5657 Control changed by flood01669000_RF3 Yes 4/5/2005 9/16/2013 60 0.9564 0.7694 0.7292 Graphical appearance

01669520 Dragon Swamp at Mascot, VA 01669520_RF1 Yes 4/7/1981 8/14/2013 227 0.9559 0.9133 0.8895 First RatFam at site
64 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013 Table 9. Rating families, dates they were in effect, variability statistics, and explanations for their causes for streamgages active in Virginia in October 2013.—Continued [GAM, generalized additive model; R2, coefficient of determination; RatFam, rating family; VA, Virginia; Rt, Route; Italicized text represents rating families that ended before the primary study period, water years 1991–2013] Streamgage number Streamgage name Rating family Used in multisite analysis? First measurement Final or most recent measurement Number of measurements Spearman’s rho

R2 of GAM 

of gage 

height as a 

function of 

flow

R2 of GAM 

of flow as 

a function 

of gage 

height

Explanation

01670400 North Anna River near Partlow, VA 01670400_RF1 No 1/18/1972 8/3/1972 20 0.9830 0.9049 0.9978 First RatFam at site

01670400_RF2 No 5/28/1975 9/17/1984 82 0.7659 0.9819 0.9493 Graphical appearance, but apparent change in measurement frequency prior to establish-ment as a continuous gage01670400_RF3 Yes 10/25/1984 10/22/2013 139 0.8692 0.9387 0.8926 Moved gage

01671020 North Anna River at Hart Corner near Doswell, VA 01671020_RF1 Yes 10/24/1979 10/16/2013 321 0.9691 0.9897 0.9829 First RatFam at site01671025 North Anna River above Little River near Doswell, VA 01671025_RF1 Yes 10/8/2004 10/29/2013 76 0.9767 0.9726 0.9767 First RatFam at site

01671100 Little River near Doswell, VA 01671100_RF1 Yes 11/9/1988 9/16/2013 164 0.9922 0.9821 0.9677 First RatFam at site

01672500 South Anna River near Ashland, VA 01672500_RF1 Yes 10/18/1930 10/29/2013 629 0.9889 0.9891 0.9832 First RatFam at site01673000 Pamunkey River near Hanover, VA 01673000_RF1 Yes 10/23/1941 10/29/2013 696 0.9887 0.9803 0.9753 First RatFam at site01673550 Totopotomoy Creek near Studley, VA 01673550_RF1 No 11/3/1977 8/10/1987 88 0.9374 0.9480 0.8830 First RatFam at site

01673550_RF2 Yes 11/15/1988 9/17/2013 209 0.9493 0.9473 0.8690 Data gap/hiatus

01673800 Po River near Spotsylvania, VA 01673800_RF1 Yes 9/24/1962 9/16/2013 454 0.9654 0.9450 0.8917 First RatFam at site01674000 Mattaponi River near Bowling Green, VA 01674000_RF1 Yes 1/19/1961 10/21/2013 457 0.9911 0.9802 0.9063 First RatFam at site01674500 Mattaponi River near Beulahville, VA 01674500_RF1 Yes 9/19/1941 10/29/2013 649 0.9951 0.9899 0.9886 First RatFam at site

02011400 Jackson River near Bacova, VA 02011400_RF1 No 6/21/1972 11/4/1985 89 0.9823 0.9929 0.9850 First RatFam at site

02011400_RF2 Yes 11/21/1985 10/30/2013 216 0.9713 0.9653 0.9595 Control changed by November 1985 flood

02011460 Back Creek near Sunrise, VA 02011460_RF1 No 5/7/1974 12/14/1977 40 0.9806 0.9946 0.9912 First RatFam at site

02011460_RF2 No 1/31/1978 11/6/1985 65 0.9918 0.9894 0.9856 Control changed by flood02011460_RF3 No 4/9/1986 2/10/2004 157 0.9735 0.9535 0.9549 Control changed by November 1985 flood, and only 

stabilized in April 1986

02011460_RF4 No 4/6/2004 10/7/2008 37 0.9970 0.9152 0.9084 Graphical appearance02011460_RF5 Yes 11/13/2008 10/30/2013 38 0.9915 0.9847 0.9839 Graphical appearance

02011470 Back Creek at Sunrise, VA 02011470_RF1 Yes 9/21/1984 10/30/2013 272 0.9820 0.9407 0.9698 First RatFam at site02011490 Little Back Creek near Sunrise, VA 02011490_RF1 Yes 9/19/1984 10/30/2013 68 0.9227 0.9858 0.9874 First RatFam at site02011500 Back Creek near Mountain Grove, VA 02011500_RF1 No 9/26/1951 12/4/1973 259 0.9449 0.9510 0.9079 First RatFam at site

02011500_RF2 Yes 1/4/1974 10/30/2013 333 0.9515 0.9524 0.9344 Control changed by flood

02011800 Jackson River below Gathright Dam near Hot Spgs, VA 02011800_RF1 Yes 10/19/1973 10/30/2013 378 0.9863 0.9938 0.9871 First RatFam at site

02013000 Dunlap Creek near Covington, VA 02013000_RF1 No 12/14/1928 8/18/1969 353 0.9734 0.9778 0.9735 First RatFam at site

02013000_RF2 No 8/20/1969 2/14/1973 33 0.9106 0.9740 0.9384 Control changed by 1969 flood02013000_RF3 No 4/3/1973 1/9/1986 102 0.9783 0.9676 0.9641 Control changed by June 1972 flood from Hurricane 

Agnes and only stabilized in April 1973

02013000_RF4 Yes 2/21/1986 10/29/2013 228 0.9536 0.9556 0.9447 Control changed by November 1985 flood, and only 

stabilized in February 1986

02013100 Jackson River below Dunlap Creek at Covington, VA 02013100_RF1 Yes 9/20/1974 10/29/2013 338 0.9630 0.9942 0.9783 First RatFam at site02014000 Potts Creek near Covington, VA 02014000_RF1 No 12/14/1928 9/9/1953 192 0.9937 0.9939 0.9919 First RatFam at site

02014000_RF2 No 10/6/1953 10/17/1956 41 0.9762 0.9971 0.9951 Established as a continuous gage02014000_RF3 No 9/8/1965 6/7/1972 82 0.9385 0.9336 0.9094 Moved gage02014000_RF4 No 6/21/1972 10/8/1985 122 0.8990 0.9305 0.8929 Control changed by June 1972 flood from Hurricane 

Agnes

02014000_RF5 No 11/14/1985 1/6/1995 62 0.8796 0.9071 0.8835 Control changed by November 1985 flood02014000_RF6 Yes 2/16/1995 10/31/2013 152 0.9506 0.9587 0.9430 Control changed by January 1996 flood

02015700 Bullpasture River at Williamsville, VA 02015700_RF1 No 8/2/1960 6/10/1974 171 0.8200 0.4591 0.8097 First RatFam at site

02015700_RF2 No 7/12/1974 5/22/1979 50 0.9810 0.1971 0.7949 Moved gage02015700_RF3 No 7/12/1979 11/4/1985 50 0.9948 0.9917 0.9870 Graphical appearance02015700_RF4 Yes 11/22/1985 9/3/2013 199 0.9844 0.9889 0.9861 Control changed by November 1985 flood

02016000 Cowpasture River near Clifton Forge, VA 02016000_RF1 Yes 3/26/1925 10/30/2013 663 0.9610 0.9659 0.9616 First RatFam at site02016500 James River at Lick Run, VA 02016500_RF1 Yes 4/4/1925 10/29/2013 617 0.9937 0.9947 0.9937 First RatFam at site
Table 9 65

Table 9. Rating families, dates they were in effect, variability statistics, and explanations for their causes for streamgages active in Virginia in October 2013.—Continued[GAM, generalized additive model; R2, coefficient of determination; RatFam, rating family; VA, Virginia; Rt, Route; Italicized text represents rating families that ended before the primary study period, water years 1991–2013]

Streamgage 

number Streamgage name Rating family

Used in 

multisite 

analysis?

First 

measurement

Final or 

most recent 

measurement

Number of 

measurements

Spearman’s 

rho

R2 of GAM 

of gage 

height as a 

function of 

flow

R2 of GAM 

of flow as 

a function 

of gage 

height

Explanation

02017500 Johns Creek at New Castle, VA 02017500_RF1 Yes 12/29/1926 9/10/2013 200 0.9846 0.9866 0.9801 First RatFam at site02018000 Craig Creek at Parr, VA 02018000_RF1 Yes 4/5/1925 10/30/2013 716 0.9901 0.9926 0.9878 First RatFam at site02018500 Catawba Creek near Catawba, VA 02018500_RF1 No 9/13/1943 7/8/1953 121 0.9908 0.9861 0.9885 First RatFam at site

02018500_RF2 No 7/31/1953 3/29/1982 257 0.9606 0.9638 0.9500 Moved gage02018500_RF3 No 11/4/1985 8/2/1994 45 0.9300 0.9640 0.9434 Data gap02018500_RF4 Yes 10/4/1994 10/22/2013 138 0.8344 0.9585 0.9050 Graphical appearance

02019500 James River at Buchanan, VA 02019500_RF1 Yes 3/30/1900 10/29/2013 708 0.9924 0.9900 0.9895 First RatFam at site02020500 Calfpasture River above Mill Creek at Goshen, VA 02020500_RF1 No 1/30/1939 5/3/1965 296 0.9717 0.9716 0.9537 First RatFam at site

02020500_RF2 No 11/21/1988 10/8/1996 70 0.9429 0.9610 0.9202 Concrete control damaged in floods while gage was 

discontinued

02020500_RF3 No 10/25/1996 8/23/1999 27 0.3516 0.5186 0.5445 Last parts of the control were removed by landowner02020500_RF4 Yes 10/5/1999 9/3/2013 101 0.9978 0.9970 0.9954 Graphical appearance, but graphical app-earance of stabilization following control removal and 1996 floods

02021500 Maury River at Rockbridge Baths, VA 02021500_RF1 Yes 12/18/1928 10/29/2013 659 0.9960 0.9946 0.9936 First RatFam at site02022500 Kerrs Creek near Lexington, VA 02022500_RF1 No 11/22/1988 12/5/1997 71 0.9897 0.9983 0.9967 First RatFam at site

02022500_RF2 Yes 2/11/1998 8/22/2013 115 0.9049 0.9398 0.8923 Graphical appearance

02024000 Maury River near Buena Vista, VA 02024000_RF1 No 3/14/1939 8/14/1969 299 0.9981 0.9978 0.9972 First RatFam at site

02024000_RF2 Yes 9/15/1969 10/29/2013 302 0.9813 0.9813 0.9739 Control changed by 1969 flood

02024752 James River at Blue Ridge Pkwy near Big Island, VA 02024752_RF1 Yes 6/8/2005 11/4/2013 51 0.9882 0.9971 0.9928 First RatFam at site02024915 Pedlar River at Forest Road near Buena Vista, VA 02024915_RF1 Yes 11/6/2002 9/17/2013 75 0.9911 0.9946 0.9897 First RatFam at site02025500 James River at Holcomb Rock, VA 02025500_RF1 Yes 9/20/1931 9/25/2013 438 0.9931 0.9949 0.9919 First RatFam at site02026000 James River at Bent Creek, VA 02026000_RF1 Yes 3/21/1925 9/26/2013 449 0.9903 0.9925 0.9883 First RatFam at site02027000 Tye River near Lovingston, VA 02027000_RF1 No 7/12/1938 6/16/1944 62 0.8571 0.9482 0.8469 First RatFam at site

02027000_RF2 No 7/4/1944 9/5/1996 69 0.8962 0.9082 0.8049 Graphical appearance02027000_RF3 No 10/18/1996 7/22/2004 67 0.9958 0.9977 0.9945 Control changed by September 1996 flood02027000_RF4 Yes 9/3/2004 9/23/2013 60 0.9976 0.9972 0.9915 Graphical appearance, but coincided with datum change

02027500 Piney River at Piney River, VA 02027500_RF1 No 9/29/1988 9/6/2000 91 0.9902 0.9826 0.9720 First RatFam at site

02027500_RF2 Yes 10/12/2000 9/23/2013 89 0.9775 0.9624 0.9205 Graphical appearance, but coincided with datum change

02028500 Rockfish River near Greenfield, VA 02028500_RF1 No 10/16/1942 10/9/2009 161 0.9896 0.9944 0.9816 First RatFam at site

02028500_RF2 Yes 12/8/2009 9/23/2013 25 0.9935 0.9886 0.9765 Graphical appearance, but coincided with datum change

02029000 James River at Scottsville, VA 02029000_RF1 Yes 2/24/1925 10/24/2013 573 0.9915 0.9902 0.9887 First RatFam at site02030000 Hardware River below Briery Run near Scottsville, VA 02030000_RF1 Yes 8/20/1969 10/16/2013 182 0.9837 0.9928 0.9812 First RatFam at site02030500 Slate River near Arvonia, VA 02030500_RF1 No 4/7/1926 6/22/1972 417 0.9930 0.9941 0.9935 First RatFam at site

02030500_RF2 Yes 6/28/1972 10/16/2013 339 0.9935 0.9950 0.9935 Control changed by June 1972 flood from Hurricane 

Agnes

02031000 Mechums River near White Hall, VA 02031000_RF1 Yes 4/17/1979 10/29/2013 240 0.9698 0.9834 0.9498 First RatFam at site02032250 Moormans River near Free Union, VA 02032250_RF1 Yes 4/9/1980 10/29/2013 148 0.9676 0.9833 0.9569 First RatFam at site02032640 North Fork Rivanna River near Earlysville, VA 02032640_RF1 Yes 10/4/1993 10/29/2013 169 0.9544 0.9543 0.9284 First RatFam at site02034000 Rivanna River at Palmyra, VA 02034000_RF1 Yes 3/26/1937 10/16/2013 172 0.9919 0.9961 0.9949 First RatFam at site02035000 James River at Cartersville, VA 02035000_RF1 Yes 4/2/1900 10/24/2013 793 0.9925 0.9832 0.9870 First RatFam at site02036500 Fine Creek at Fine Creek Mills, VA 02036500_RF1 Yes 12/29/1958 9/10/2013 186 0.9702 0.9873 0.9324 First RatFam at site02037000 James River And Kanawha Canal near Richmond, VA 02037000_RF1 Yes 10/23/1961 9/17/2013 213 0.3796 0.4690 0.4728 First RatFam at site02037500 James River near Richmond, VA 02037500_RF1 Yes 8/24/1988 11/5/2013 135 0.9961 0.9930 0.9923 First RatFam at site02038850 Holiday Creek near Andersonville, VA 02038850_RF1 Yes 5/2/1966 9/26/2013 401 0.9379 0.9644 0.9413 First RatFam at site02039000 Buffalo Creek near Hampden Sydney, VA 02039000_RF1 No 8/21/1946 7/6/1956 122 0.9669 0.9803 0.9793 First RatFam at site

02039000_RF2 No 8/9/1956 12/6/1978 277 0.9170 0.9167 0.9181 Graphical appearance02039000_RF3 Yes 9/19/1988 9/12/2013 178 0.8797 0.8812 0.8259 Data gap/hiatus

02039500 Appomattox River at Farmville, VA 02039500_RF1 Yes 3/25/1926 9/26/2013 720 0.9802 0.9864 0.9520 First RatFam at site
66 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013 Table 9. Rating families, dates they were in effect, variability statistics, and explanations for their causes for streamgages active in Virginia in October 2013.—Continued [GAM, generalized additive model; R2, coefficient of determination; RatFam, rating family; VA, Virginia; Rt, Route; Italicized text represents rating families that ended before the primary study period, water years 1991–2013] Streamgage number Streamgage name Rating family Used in multisite analysis? First measurement Final or most recent measurement Number of measurements Spearman’s rho

R2 of GAM 

of gage 

height as a 

function of 

flow

R2 of GAM 

of flow as 

a function 

of gage 

height

Explanation

02040000 Appomattox River at Mattoax, VA 02040000_RF1 No 8/25/1900 9/6/1905 28 0.9845 0.9882 0.9925 First RatFam at site

02040000_RF2 No 3/27/1926 10/6/1958 241 0.9905 0.9928 0.9871 Established as a continuous gage02040000_RF3 Yes 9/15/1988 9/10/2013 175 0.9791 0.9799 0.9604 Data gap

02040892 Appomattox River at Route 602 near Mannboro, VA 02040892_RF1 Yes 6/22/2011 10/23/2013 31 0.9972 0.9985 0.9984 First RatFam at site02041000 Deep Creek near Mannboro, VA 02041000_RF1 Yes 9/6/1979 9/10/2013 188 0.9789 0.9579 0.9103 First RatFam at site02041650 Appomattox River at Matoaca, VA 02041650_RF1 Yes 10/30/1969 9/11/2013 375 0.9956 0.9939 0.9926 First RatFam at site02042500 Chickahominy River near Providence Forge, VA 02042500_RF1 Yes 11/7/1941 10/23/2013 647 0.9896 0.9798 0.9216 First RatFam at site02044500 Nottoway River near Rawlings, VA 02044500_RF1 Yes 10/24/1971 9/11/2013 254 0.9928 0.9955 0.9842 First RatFam at site02045500 Nottoway River near Stony Creek, VA 02045500_RF1 Yes 3/21/1930 9/11/2013 760 0.9838 0.9677 0.9552 First RatFam at site02046000 Stony Creek near Dinwiddie, VA 02046000_RF1 Yes 10/6/1972 9/10/2013 256 0.9662 0.9661 0.9110 First RatFam at site02047000 Nottoway River near Sebrell, VA 02047000_RF1 Yes 9/24/1941 11/7/2013 649 0.9969 0.9939 0.9904 First RatFam at site02047500 Blackwater River near Dendron, VA 02047500_RF1 No 1/8/1942 7/13/1976 365 0.9912 0.9839 0.9805 First RatFam at site

02047500_RF2 Yes 10/6/1976 10/17/2012 225 0.9836 0.9518 0.9239 Graphical appearance

02049500 Blackwater River near Franklin, VA 02049500_RF1 No 8/24/1944 8/14/1973 289 0.9953 0.9911 0.9885 First RatFam at site

02049500_RF2 Yes 10/3/1973 11/4/2013 284 0.9847 0.9629 0.9061 Graphical appearance

02051000 North Meherrin River near Lunenburg, VA 02051000_RF1 Yes 10/8/1980 9/12/2013 240 0.9319 0.9401 0.9173 First RatFam at site02051500 Meherrin River near Lawrenceville, VA 02051500_RF1 Yes 12/19/1928 11/6/2013 653 0.9941 0.9931 0.9888 First RatFam at site02052000 Meherrin River at Emporia, VA 02052000_RF1 Yes 10/9/1980 9/11/2013 245 0.9856 0.9772 0.9472 First RatFam at site02053800 South Fork Roanoke River near Shawsville, VA 02053800_RF1 No 10/5/1980 10/1/1985 43 0.9894 0.9928 0.9916 First RatFam at site

02053800_RF2 No 6/18/1986 9/27/1988 20 0.6938 0.8168 0.9163 Control changed by November 1985 flood02053800_RF3 No 11/21/1988 8/20/1996 59 0.9667 0.9545 0.9622 Graphical appearance02053800_RF4 No 1/8/1998 8/24/2004 54 0.9895 0.9906 0.9899 Data gap02053800_RF5 Yes 9/8/2004 10/22/2013 62 0.9062 0.8783 0.9021 Graphical appearance

02054500 Roanoke River at Lafayette, VA 02054500_RF1 Yes 7/4/1948 10/22/2013 248 0.8797 0.9221 0.8966 First RatFam at site02054530 Roanoke River at Glenvar, VA 02054530_RF1 Yes 10/16/1991 10/22/2013 162 0.9974 0.9980 0.9976 First RatFam at site02055000 Roanoke River at Roanoke, VA 02055000_RF1 Yes 3/19/1900 10/29/2013 783 0.9809 0.9734 0.9787 First RatFam at site02055100 Tinker Creek near Daleville, VA 02055100_RF1 Yes 4/27/1956 10/29/2013 490 0.8608 0.9241 0.8496 First RatFam at site02056000 Roanoke River at Niagara, VA 02056000_RF1 Yes 7/11/1926 10/29/2013 588 0.9927 0.9858 0.9868 First RatFam at site02056650 Back Creek near Dundee, VA 02056650_RF1 No 8/15/1974 10/2/1985 95 0.9910 0.9833 0.9899 First RatFam at site

02056650_RF2 Yes 11/25/1985 10/21/2013 215 0.9885 0.9881 0.9718 Control changed by November 1985 flood

02056900 Blackwater River near Rocky Mount, VA 02056900_RF1 Yes 10/26/1976 10/21/2013 275 0.9938 0.9916 0.9792 First RatFam at site02058400 Pigg River near Sandy Level, VA 02058400_RF1 Yes 5/8/1962 9/10/2013 382 0.9862 0.9939 0.9857 First RatFam at site02059485 Goose Creek at Rt 747 near Bunker Hill, VA 02059485_RF1 Yes 12/12/2006 9/25/2013 54 0.9820 0.9862 0.9791 First RatFam at site02059500 Goose Creek near Huddleston, VA 02059500_RF1 Yes 10/6/1980 10/21/2013 254 0.9717 0.9265 0.9470 First RatFam at site02060500 Roanoke River at Altavista, VA 02060500_RF1 No 7/15/1930 4/15/1969 343 0.9850 0.9844 0.9731 First RatFam at site

02060500_RF2 No 6/4/1969 8/25/1988 138 0.9508 0.9849 0.9803 Graphical appearance02060500_RF3 Yes 8/6/1990 11/5/2013 162 0.9668 0.9912 0.9892 Data gap/hiatus

02061000 Big Otter River near Bedford, VA 02061000_RF1 Yes 12/12/2006 9/25/2013 57 0.9770 0.9720 0.9152 First RatFam at site02061500 Big Otter River near Evington, VA 02061500_RF1 No 11/3/1936 10/1/1973 326 0.9930 0.9944 0.9916 First RatFam at site

02061500_RF2 No 5/14/1975 5/23/2005 236 0.9472 0.9610 0.9465 Bridge construction02061500_RF3 Yes 7/25/2005 10/21/2013 58 0.9900 0.9905 0.9839 Graphical appearance but coincided with datum change

02062500 Roanoke (Staunton) River at Brookneal, VA 02062500_RF1 No 4/29/1923 6/5/1941 89 0.9836 0.9884 0.9863 First RatFam at site

02062500_RF2 Yes 7/17/1941 11/4/2013 547 0.9649 0.9721 0.9542 Moved gage

02064000 Falling River near Naruna, VA 02064000_RF1 Yes 7/12/1929 9/12/2013 643 0.9754 0.9924 0.9751 First RatFam at site02065500 Cub Creek at Phenix, VA 02065500_RF1 Yes 7/6/1972 9/12/2013 242 0.9607 0.9761 0.9455 First RatFam at site02066000 Roanoke (Staunton) River at Randolph, VA 02066000_RF1 Yes 4/17/1930 9/9/2013 506 0.9818 0.9874 0.9813 First RatFam at site02069700 South Mayo River near Nettleridge, VA 02069700_RF1 Yes 6/21/1972 10/23/2013 235 0.9847 0.9930 0.9860 First RatFam at site02070000 North Mayo River near Spencer, VA 02070000_RF1 Yes 4/20/1939 10/23/2013 237 0.9941 0.9960 0.9947 First RatFam at site
Table 9 67

Table 9. Rating families, dates they were in effect, variability statistics, and explanations for their causes for streamgages active in Virginia in October 2013.—Continued[GAM, generalized additive model; R2, coefficient of determination; RatFam, rating family; VA, Virginia; Rt, Route; Italicized text represents rating families that ended before the primary study period, water years 1991–2013]

Streamgage 

number Streamgage name Rating family

Used in 

multisite 

analysis?

First 

measurement

Final or 

most recent 

measurement

Number of 

measurements

Spearman’s 

rho

R2 of GAM 

of gage 

height as a 

function of 

flow

R2 of GAM 

of flow as 

a function 

of gage 

height

Explanation

02071530 Smith River at Smith Riv Church near Woolwine, VA 02071530_RF1 No 8/17/1994 10/5/2005 92 0.9217 0.9566 0.9250 First RatFam at site

02071530_RF2 Yes 12/14/2005 10/23/2013 51 0.9844 0.9703 0.9712 Graphical appearance

02072000 Smith River near Philpott, VA 02072000_RF1 No 9/18/1946 10/1/1952 85 0.9929 0.9987 0.9977 First RatFam at site

02072000_RF2 Yes 11/19/1952 9/11/2013 419 0.9623 0.9965 0.9918 Moved gage

02072500 Smith River at Bassett, VA 02072500_RF1 No 4/21/1939 4/10/1956 179 0.9879 0.9944 0.9701 First RatFam at site

02072500_RF2 Yes 7/24/1956 11/6/2013 459 0.9331 0.9900 0.9857 Graphical appearance

02073000 Smith River at Martinsville, VA 02073000_RF1 Yes 10/19/1937 9/11/2013 193 0.9816 0.9913 0.9870 First RatFam at site02074500 Sandy River near Danville, VA 02074500_RF1 Yes 9/28/1983 9/11/2013 176 0.9854 0.9893 0.9849 First RatFam at site02075045 Dan River at Stp near Danville, VA 02075045_RF1 Yes 10/28/1993 11/5/2013 145 0.9860 0.9953 0.9917 First RatFam at site02075500 Dan River at Paces, VA 02075500_RF1 No 11/10/1950 12/14/1971 205 0.9944 0.9953 0.9946 First RatFam at site

02075500_RF2 Yes 2/1/1972 11/6/2013 277 0.9907 0.9886 0.9884 Graphical appearance

02077000 Banister River at Halifax, VA 02077000_RF1 No 1/25/1929 3/20/1946 122 0.9722 0.9724 0.9724 First RatFam at site

02077000_RF2 No 6/6/1946 9/6/1950 51 0.8436 0.9198 0.9897 Graphical appearance02077000_RF3 No 10/6/1950 8/25/1970 183 0.9740 0.7193 0.9458 Moved gage02077000_RF4 No 12/3/1981 8/14/2002 85 0.8665 0.9746 0.9435 Data gap02077000_RF6 Yes 7/7/2005 11/7/2013 50 0.9854 0.9973 0.9935 Graphical appearance, but followed a datum change

02077500 Hyco River near Denniston, VA 02077500_RF1 No 7/11/1929 12/3/1981 317 0.9827 0.9869 0.9466 First RatFam at site

02077500_RF2 No 3/10/1982 1/22/2003 147 0.9780 0.9846 0.9536 Graphical appearance02077500_RF3 Yes 3/12/2003 9/12/2013 66 0.9576 0.9817 0.9705 Graphical appearance

02079640 Allen Creek near Boydton, VA 02079640_RF1 No 9/22/1961 10/21/1996 353 0.9502 0.9631 0.9340 First RatFam at site

02079640_RF2 Yes 9/7/2000 8/22/2013 107 0.7852 0.8382 0.6796 Data gap/hiatus

03164000 New River near Galax, VA 03164000_RF1 Yes 11/24/1929 10/18/2013 636 0.9873 0.9856 0.9847 First RatFam at site03165000 Chestnut Creek at Galax, VA 03165000_RF1 No 8/14/1940 5/6/1948 49 0.9851 0.9953 0.9938 First RatFam at site

03165000_RF2 No 7/8/1948 1/9/1951 31 0.9812 0.9981 0.9975 Established as a continuous gage03165000_RF3 No 2/27/1951 5/11/1953 27 0.9714 0.9682 0.9611 Graphical appearance03165000_RF4 No 6/8/1953 10/10/1968 157 0.9084 0.9019 0.8735 Moved gage03165000_RF5 No 11/21/1968 10/17/1975 60 0.9441 0.9178 0.8293 Graphical appearance03165000_RF6 No 11/26/1975 7/23/1979 27 0.9056 0.8663 0.9420 Graphical appearance03165000_RF7 Yes 8/31/1979 10/18/2013 288 0.9744 0.3989 0.9660 Concrete control built

03165500 New River at Ivanhoe, VA 03165500_RF1 Yes 10/2/1927 10/21/2013 497 0.9886 0.9890 0.9882 First RatFam at site03167000 Reed Creek at Grahams Forge, VA 03167000_RF1 Yes 2/3/1927 10/28/2013 712 0.9947 0.9909 0.9926 First RatFam at site03168000 New River at Allisonia, VA 03168000_RF1 Yes 1/7/1930 10/21/2013 630 0.9926 0.9889 0.9899 First RatFam at site03170000 Little River at Graysontown, VA 03170000_RF1 No 10/30/1928 11/20/1931 28 0.9800 0.9929 0.9720 First RatFam at site

03170000_RF2 No 1/16/1932 7/15/1940 46 0.9672 0.9667 0.9723 Moved gage03170000_RF4 Yes 9/15/1942 10/24/2013 646 0.9790 0.9799 0.9769 Moved gage

03171000 New River at Radford, VA 03171000_RF1 Yes 7/12/1939 10/24/2013 452 0.9947 0.9952 0.9932 First RatFam at site03173000 Walker Creek at Bane, VA 03173000_RF1 Yes 3/31/1938 10/28/2013 668 0.9979 0.9971 0.9966 First RatFam at site03175500 Wolf Creek near Narrows, VA 03175500_RF1 Yes 6/8/1909 10/28/2013 676 0.9615 0.9648 0.9429 First RatFam at site03176500 New River at Glen Lyn, VA 03176500_RF1 No 9/2/1927 1/10/1957 220 0.9972 0.9971 0.9964 First RatFam at site

03176500_RF2 No 3/5/1957 4/17/1987 264 0.9678 0.9522 0.9486 Graphical appearance03176500_RF3 Yes 5/13/1987 10/22/2013 206 0.9963 0.9405 0.9361 Graphical appearance

03177710 Bluestone River at Falls Mills, VA 03177710_RF1 Yes 9/25/1980 10/22/2013 237 0.9553 0.9786 0.9440 First RatFam at site03207800 Levisa Fork at Big Rock, VA 03207800_RF1 No 9/18/1967 2/13/1989 204 0.9032 0.9102 0.8463 First RatFam at site

03207800_RF2 Yes 4/10/1989 10/28/2013 193 0.9807 0.9727 0.9674 Graphical appearance

03208500 Russell Fork at Haysi, VA 03208500_RF1 No 7/19/1926 12/20/1939 45 0.9984 0.9984 0.9976 First RatFam at site

03208500_RF2 Yes 3/6/1940 10/23/2013 715 0.9863 0.9850 0.9771 Moved gage and changed datum 

03208950 Cranes Nest River near Clintwood, VA 03208950_RF1 No 9/27/1963 5/31/2007 393 0.9633 0.9636 0.9435 First RatFam at site
68 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013 Table 9. Rating families, dates they were in effect, variability statistics, and explanations for their causes for streamgages active in Virginia in October 2013.—Continued [GAM, generalized additive model; R2, coefficient of determination; RatFam, rating family; VA, Virginia; Rt, Route; Italicized text represents rating families that ended before the primary study period, water years 1991–2013] Streamgage number Streamgage name Rating family Used in multisite analysis? First measurement Final or most recent measurement Number of measurements Spearman’s rho

R2 of GAM 

of gage 

height as a 

function of 

flow

R2 of GAM 

of flow as 

a function 

of gage 

height

Explanation

03208950_RF2 Yes 7/16/2007 10/23/2013 52 0.8062 0.8578 0.8511 Graphical appearance

03209000 Pound River below Flannagan Dam, near Haysi, VA 03209000_RF1 Yes 12/4/1961 10/23/2013 422 0.9898 0.9968 0.9940 First RatFam at site03471500 South Fork Holston River at Riverside, near Chilhowie, VA 03471500_RF1 No 3/20/1909 12/28/1931 40 0.9039 0.7900 0.8869 First RatFam at site

03471500_RF2 No 7/17/1942 12/5/1956 174 0.9966 0.9976 0.9967 Data gap03471500_RF3 No 1/9/1957 11/6/1977 237 0.9948 0.9944 0.9930 Graphical appearance03471500_RF4 No 11/18/1977 8/18/1989 96 0.9879 0.9912 0.9864 Control changed by flood03471500_RF5 Yes 10/6/1989 10/18/2013 200 0.9869 0.9837 0.9827 Graphical appearance

03473000 South Fork Holston River near Damascus, VA 03473000_RF1 No 11/12/1931 7/26/1951 191 0.9979 0.9976 0.9967 First RatFam at site

03473000_RF2 No 8/14/1951 10/20/2003 478 0.9732 0.9710 0.9637 Bridge construction noted on measurement form03473000_RF3 Yes 12/12/2003 10/17/2013 71 0.9943 0.9886 0.9865 Control change believed due to a piece of construction 

equipment breaking a piece of rock off a ledge and leaving it on the control.

03474000 Middle Fork Holston River at Seven Mile Ford, VA 03474000_RF1 No 7/17/1942 9/8/1953 144 0.9828 0.9908 0.9829 First RatFam at site

03474000_RF2 No 9/14/1953 2/2/1961 94 0.9785 0.9952 0.9849 Concrete control built03474000_RF3 No 3/2/1961 9/11/1962 28 0.6383 0.6268 0.4927 Graphical appearance03474000_RF4 Yes 11/7/1962 10/18/2013 355 0.9949 0.9960 0.9954 New concrete control built

03475000 Middle Fork Holston River near Meadowview, VA 03475000_RF1 Yes 11/6/1931 10/29/2013 529 0.9907 0.9919 0.9882 First RatFam at site03478400 Beaver Creek at Bristol, VA 03478400_RF1 No 7/11/1957 4/6/1972 185 0.9695 0.9751 0.9587 First RatFam at site

03478400_RF2 No 5/2/1972 11/4/2008 307 0.9665 0.9699 0.9514 Graphical appearance; approximate time that Interstate 

81 bridge was built, and subsequent measurement forms discuss fill downstream

03478400_RF3 No 1/6/2009 2/28/2012 36 0.9889 0.9845 0.9920 New control from stream restoration project03478400_RF4 Yes 4/5/2012 10/29/2013 24 0.9821 0.9977 0.9855 Bridge construction

03488000 North Fork Holston River near Saltville, VA 03488000_RF1 No 11/2/1920 4/11/1934 47 0.9630 0.9515 0.9516 First RatFam at site

03488000_RF2 Yes 6/16/1934 10/18/2013 871 0.9864 0.9772 0.9781 Moved gage and changed datum.

03490000 North Fork Holston River near Gate City, VA 03490000_RF1 Yes 10/18/1931 10/17/2013 557 0.9939 0.9934 0.9912 First RatFam at site03524000 Clinch River at Cleveland, VA 03524000_RF1 No 10/9/1920 4/24/1931 40 0.9932 0.9941 0.9925 First RatFam at site

03524000_RF2 Yes 11/9/1931 10/22/2013 706 0.9932 0.9909 0.9892 Moved gage and changed datum.

03524500 Guest River at Coeburn, VA 03524500_RF1 Yes 6/7/1949 10/22/2013 185 0.9759 0.9861 0.9651 First RatFam at site03527000 Clinch River at Speers Ferry, VA 03527000_RF1 Yes 1/4/1927 10/17/2013 641 0.9920 0.9892 0.9874 First RatFam at site03529500 Powell River at Big Stone Gap, VA 03529500_RF1 No 10/27/1944 4/5/1977 180 0.9939 0.9929 0.9876 First RatFam at site

03529500_RF2 No 4/5/1978 10/5/1981 34 0.9357 0.9709 0.9594 Data gap/hiatus03529500_RF3 Yes 9/19/2001 10/21/2013 112 0.9496 0.7520 0.7925 Data gap/hiatus

03531500 Powell River near Jonesville, VA 03531500_RF1 Yes 11/8/1931 10/21/2013 800 0.9928 0.9904 0.9880 First RatFam at site
Table 13 69

Table 13. Number of days with estimated and qualified flows for streamgages in Virginia, water years 1991–2013.—Continued[A:e, National Water Information System (NWIS) remark code indicating that a daily flow value was estimated; A:1, NWIS remark code indicating that a daily flow value was write-protected without a remark code; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name

Estimated (A:e) Write-protected (A:1)

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

Percentage 

estimated 

overall

Percentage 

estimated 

during winter

Total Total daily values

01613900 Hogue Creek near Hayfield, VA 105 69 8 2 3 0 2 5 8 35 23 37 297 0.07 0.19 20 4,38101615000 Opequon Creek near Berryville, VA 128 65 0 1 1 0 2 2 30 52 44 52 377 0.06 0.15 17 6,58501616100 Dry Marsh Run near Berryville, VA 39 33 31 34 40 51 27 33 32 42 33 33 428 0.11 0.10 27 4,05701620500 North River near Stokesville, VA 42 57 15 2 14 13 18 9 15 35 26 6 252 0.06 0.10 46 4,41001621050 Muddy Creek at Mount Clinton, VA 72 41 21 26 9 2 16 0 26 10 11 62 296 0.05 0.12 37 6,13801622000 North River near Burketown, VA 17 3 6 0 0 10 5 5 24 4 0 1 75 0.02 0.02 5 4,44201625000 Middle River near Grottoes, VA 128 45 5 0 0 0 4 0 14 42 30 41 309 0.04 0.10 5 8,40001626000 South River near Waynesboro, VA 55 27 7 13 12 0 4 0 21 26 4 10 179 0.02 0.04 9 8,40001626850 South River near Dooms, VA 22 13 0 1 1 0 4 0 24 6 16 4 91 0.02 0.03 4 5,25601627500 South River at Harriston, VA 23 8 2 0 1 0 0 0 6 1 5 7 53 0.01 0.03 8 4,68101628500 South Fork Shenandoah River near Lynnwood, VA 51 43 0 0 0 5 0 0 1 0 0 5 105 0.01 0.05 12 8,40001629500 South Fork Shenandoah River near Luray, VA 21 9 15 24 16 15 34 6 25 1 2 0 168 0.04 0.03 23 4,44301631000 South Fork Shenandoah River at Front Royal, VA 63 14 3 0 8 7 21 15 4 3 7 14 159 0.04 0.08 50 4,42801632000 North Fork Shenandoah River at Cootes Store, VA 93 50 8 0 12 7 58 113 85 69 40 24 559 0.09 0.11 56 6,04601632082 Linville Creek at Broadway, VA 130 49 12 1 11 15 1 26 70 49 60 46 470 0.06 0.11 16 8,39901632900 Smith Creek near New Market, VA 160 66 1 2 2 11 6 40 52 58 39 57 494 0.06 0.14 11 8,39901633000 North Fork Shenandoah River at Mount Jackson, VA 38 13 0 0 1 0 0 0 0 8 5 3 68 0.01 0.05 10 4,57701634000 North Fork Shenandoah River near Strasburg, VA 112 44 0 0 0 8 32 14 2 13 2 20 247 0.04 0.11 96 6,20701634500 Cedar Creek near Winchester, VA 234 106 23 10 26 26 26 18 20 74 54 71 688 0.08 0.20 14 8,39201635500 Passage Creek near Buckton, VA 249 163 8 1 24 4 0 5 0 6 4 77 541 0.06 0.24 6 8,39001636316 Spout Run at Rt 621 near Millwood, VA 33 32 31 21 37 33 12 4 16 52 30 34 335 0.08 0.10 43 4,04401636690 Piney Run near Lovettsville, VA 68 70 39 11 3 0 0 0 0 0 0 20 211 0.05 0.15 9 4,36801638350 South Fork Catoctin Creek at Rt 698 near Waterford, VA 82 42 2 0 4 0 17 21 4 0 0 19 191 0.04 0.13 41 4,44301638420 North Fork Catoctin Creek at Rt 681 near Waterford, VA 73 36 5 0 0 0 5 2 19 6 1 31 178 0.04 0.13 31 4,44301638480 Catoctin Creek at Taylorstown, VA 88 65 26 12 21 27 6 11 7 29 6 28 326 0.07 0.17 23 4,38201643590 Limestone Branch near Leesburg, VA 16 8 0 0 2 0 1 0 0 0 12 10 49 0.01 0.03 32 4,40801643700 Goose Creek near Middleburg, VA 63 73 11 2 2 10 18 11 8 1 8 35 242 0.05 0.16 49 4,44201643805 North Fork Goose Creek at Rt 729 near Lincoln, VA 111 78 37 58 43 51 41 54 47 31 36 48 635 0.14 0.22 10 4,40801643880 Beaverdam Creek at Rt 734 near Mountville, VA 37 39 2 0 0 0 3 24 14 3 0 38 160 0.04 0.10 38 4,44301644000 Goose Creek near Leesburg, VA 80 55 1 1 15 10 2 10 47 25 13 12 271 0.06 0.13 11 4,63401644280 Broad Run near Leesburg, VA 32 30 6 0 1 27 10 13 0 18 21 32 190 0.04 0.09 28 4,24001645704 Difficult Run above Fox Lake near Fairfax, VA 0 0 0 0 5 31 13 3 2 4 13 1 72 0.03 0.00 9 2,19601645762 South Fork Little Difficult Run above Mouth near Vienna, VA 5 1 0 9 10 7 8 1 0 21 23 7 92 0.04 0.02 36 2,19601646000 Difficult Run near Great Falls, VA 165 82 8 6 4 2 2 9 17 105 78 57 535 0.06 0.15 10 8,39301646305 Dead Run at Whann Avenue near Mclean, VA 2 3 0 0 1 10 5 0 0 0 1 0 22 0.01 0.01 10 2,05001652500 Fourmile Run at Alexandria, VA 58 71 34 16 15 7 25 7 23 11 27 26 320 0.06 0.11 62 5,47301653000 Cameron Run at Alexandria, VA 64 27 29 56 19 35 1 2 12 20 1 10 276 0.04 0.07 11 6,20801654000 Accotink Creek near Annandale, VA 110 66 3 7 7 8 46 24 41 40 62 42 456 0.10 0.20 11 4,3830165389205 Accotink Creek near Ranger Road at Fairfax, VA 0 1 5 2 0 0 0 0 0 0 1 0 9 0.01 0.01 22 70101656000 Cedar Run near Catlett, VA 170 121 44 18 26 2 6 4 33 3 12 63 502 0.06 0.17 18 8,39301656903 Flatlick Branch above Frog Branch at Chantilly, VA 0 2 0 0 0 12 23 27 24 6 1 1 96 0.04 0.01 8 2,19601658500 South Fork Quantico Creek near Independent Hill, VA 34 12 3 1 0 7 30 37 6 58 10 14 212 0.03 0.04 34 6,18101660400 Aquia Creek near Garrisonville, VA 112 49 18 0 29 30 86 96 57 19 14 79 589 0.12 0.19 13 5,06801662800 Battle Run near Laurel Mills, VA 164 82 6 7 17 33 4 35 32 67 43 41 531 0.07 0.15 5 7,58401663500 Hazel River at Rixeyville, VA 73 27 6 4 24 16 20 2 19 15 0 18 224 0.05 0.11 52 4,365
70 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013 Table 13. Number of days with estimated and qualified flows for streamgages in Virginia, water years 1991–2013.—Continued [A:e, National Water Information System (NWIS) remark code indicating that a daily flow value was estimated; A:1, NWIS remark code indicating that a daily flow value was write-protected without a remark code; VA, Virginia; Rt, Route] Streamgage number Streamgage name Estimated (A:e) Write-protected (A:1) Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Total Percentage estimated overall Percentage estimated during winter Total Total daily values 01664000 Rappahannock River at Remington, VA 39 7 2 2 4 0 20 34 10 3 0 10 131 0.03 0.05 28 4,381 01665500 Rapidan River near Ruckersville, VA 109 45 21 2 0 0 13 9 9 4 17 72 301 0.06 0.17 1 5,464 01666500 Robinson River near Locust Dale, VA 168 77 47 12 36 16 14 14 42 4 0 30 460 0.05 0.13 5 8,398 01667500 Rapidan River near Culpeper, VA 50 40 20 38 4 15 4 4 6 11 0 2 194 0.04 0.08 4 4,631 01668000 Rappahannock River near Fredericksburg, VA 69 12 3 0 0 12 15 1 4 6 5 38 165 0.03 0.10 32 4,725 01669000 Piscataway Creek near Tappahannock, VA 73 29 12 1 1 0 15 4 9 39 52 13 248 0.06 0.11 4 4,396 01669520 Dragon Swamp at Mascot, VA 59 19 4 0 2 0 2 27 2 11 6 8 140 0.03 0.08 2 4,562 01670400 North Anna River near Partlow, VA 0 0 0 0 0 3 11 11 3 30 30 0 88 0.02 0.00 9 4,198 01671020 North Anna River at Hart Corner near Doswell, VA 69 43 14 9 24 27 14 38 32 18 5 31 324 0.06 0.10 6 5,537 01671025 North Anna River above Little River near Doswell, VA 10 1 4 5 30 10 11 8 0 8 19 10 116 0.04 0.03 11 3,189 01671100 Little River near Doswell, VA 31 19 13 0 2 0 2 5 14 33 0 6 125 0.03 0.05 3 4,436 01672500 South Anna River near Ashland, VA 36 23 2 0 0 13 24 18 21 2 0 5 144 0.04 0.07 30 3,880 01673000 Pamunkey River near Hanover, VA 34 11 13 0 2 22 11 2 9 6 13 21 144 0.02 0.04 33 6,060 01673550 Totopotomoy Creek near Studley, VA 131 29 20 23 40 21 42 78 84 47 50 51 616 0.07 0.10 3 8,400 01673800 Po River near Spotsylvania, VA 84 45 0 29 34 9 15 26 102 136 101 29 610 0.07 0.08 7 8,393 01674000 Mattaponi River near Bowling Green, VA 91 47 0 7 0 4 22 10 40 122 122 56 521 0.06 0.09 8 8,392 01674500 Mattaponi River near Beulahville, VA 56 15 4 0 0 3 4 14 36 6 1 17 156 0.02 0.05 50 6,613 02011400 Jackson River near Bacova, VA 130 29 0 0 0 0 1 0 0 0 7 47 214 0.03 0.12 30 6,937 02011460 Back Creek near Sunrise, VA 73 15 0 0 0 0 0 0 0 0 3 10 101 0.02 0.09 15 4,465 02011470 Back Creek at Sunrise, VA 0 1 0 0 5 0 4 3 0 0 0 0 13 0.00 0.00 32 6,937 02011490 Little Back Creek near Sunrise, VA 35 20 2 3 3 1 1 0 1 0 0 6 72 0.02 0.06 88 4,017 02011500 Back Creek near Mountain Grove, VA 36 34 2 2 0 5 0 1 0 2 0 8 90 0.01 0.05 27 6,937 02011800 Jackson River below Gathright Dam near Hot Spgs, VA 0 0 0 0 5 0 4 1 0 9 0 0 19 0.00 0.00 72 6,936 02013000 Dunlap Creek near Covington, VA 68 17 2 0 5 0 6 3 25 0 0 29 155 0.02 0.07 37 6,607 02013100 Jackson River below Dunlap Creek at Covington, VA 15 0 2 1 1 0 0 0 0 0 8 10 37 0.01 0.02 28 6,671 02014000 Potts Creek near Covington, VA 73 11 1 1 0 0 0 2 0 0 0 21 109 0.02 0.06 34 6,802 02015700 Bullpasture River at Williamsville, VA 107 80 30 1 2 0 11 0 3 1 30 49 314 0.06 0.17 5 5,502 02016000 Cowpasture River near Clifton Forge, VA 57 6 0 0 0 4 0 0 0 0 0 11 78 0.02 0.06 18 5,067 02016500 James River at Lick Run, VA 24 3 4 0 0 0 2 2 0 0 0 6 41 0.01 0.02 24 5,669 02017500 Johns Creek at New Castle, VA 52 30 3 1 7 5 13 5 5 3 4 21 149 0.03 0.10 14 4,382 02018000 Craig Creek at Parr, VA 29 4 0 0 0 2 11 3 5 2 0 4 60 0.01 0.03 67 4,383 02018500 Catawba Creek near Catawba, VA 40 12 1 1 2 0 0 0 7 16 24 12 115 0.03 0.06 4 4,382 02019500 James River at Buchanan, VA 18 2 4 4 6 6 0 0 0 0 0 5 45 0.01 0.02 21 5,621 02020500 Calfpasture River above Mill Creek at Goshen, VA 152 62 40 17 0 7 6 0 7 19 34 84 428 0.08 0.22 5 5,465 02021500 Maury River at Rockbridge Baths, VA 110 38 0 0 0 1 8 13 10 0 25 27 232 0.04 0.12 11 6,139 02022500 Kerrs Creek near Lexington, VA 41 14 3 0 2 0 0 11 4 5 6 14 100 0.02 0.06 21 4,569

02024000 Maury River near Buena Vista, VA 66 22 0 0 15 24 20 3 0 8 14 20 192 0.04 0.09 10 5,10902024752 James River at Blue Ridge Pkwy near Big Island, VA 19 0 0 0 5 0 0 0 0 4 0 2 30 0.01 0.03 27 2,55402024915 Pedlar River at Forest Road near Buena Vista, VA 79 24 2 0 1 0 10 9 18 4 8 29 184 0.05 0.13 85 3,97502025500 James River at Holcomb Rock, VA 32 20 28 11 14 9 0 24 30 9 0 13 190 0.04 0.05 23 5,36602026000 James River at Bent Creek, VA 2 0 5 4 7 11 1 0 3 18 7 1 59 0.01 0.00 81 4,36702027000 Tye River near Lovingston, VA 109 22 50 2 16 32 26 54 21 46 25 89 492 0.09 0.16 23 5,46702027500 Piney River at Piney River, VA 51 11 21 5 8 0 0 1 5 11 16 18 147 0.03 0.07 6 4,56902028500 Rockfish River near Greenfield, VA 93 26 5 2 24 0 9 5 6 28 47 26 271 0.05 0.11 17 5,54402029000 James River at Scottsville, VA 11 6 2 12 2 16 26 0 1 0 11 1 88 0.01 0.01 19 6,154
Table 13 71

Table 13. Number of days with estimated and qualified flows for streamgages in Virginia, water years 1991–2013.—Continued[A:e, National Water Information System (NWIS) remark code indicating that a daily flow value was estimated; A:1, NWIS remark code indicating that a daily flow value was write-protected without a remark code; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name

Estimated (A:e) Write-protected (A:1)

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

Percentage 

estimated 

overall

Percentage 

estimated 

during winter

Total Total daily values

02030000 Hardware River below Briery Run near Scottsville, VA 102 23 3 8 14 8 17 3 7 18 4 41 248 0.04 0.11 10 5,84202030500 Slate River near Arvonia, VA 42 13 1 30 0 0 0 2 0 0 0 18 106 0.02 0.06 7 4,83402031000 Mechums River near White Hall, VA 72 19 7 2 9 3 10 10 0 40 15 21 208 0.05 0.10 6 4,36902032250 Moormans River near Free Union, VA 47 28 43 15 70 20 6 4 0 32 64 42 371 0.12 0.16 5 3,00802032640 North Fork Rivanna River near Earlysville, VA 153 55 41 23 17 9 58 47 47 30 17 37 534 0.07 0.14 4 7,30202034000 Rivanna River at Palmyra, VA 33 3 1 2 1 1 0 8 19 6 2 2 78 0.02 0.03 8 4,52102035000 James River at Cartersville, VA 12 34 15 32 8 58 61 35 18 4 6 7 290 0.03 0.03 31 8,37202036500 Fine Creek at Fine Creek Mills, VA 101 18 0 6 11 55 37 59 79 65 30 32 493 0.06 0.07 4 8,39302037000 James River And Kanawha Canal near Richmond, VA 0 0 1 1 0 3 1 0 0 0 0 0 6 0.00 0.00 17 4,56902037500 James River near Richmond, VA 11 2 11 9 4 6 12 5 6 6 3 5 80 0.01 0.01 5 5,81602038850 Holiday Creek near Andersonville, VA 82 72 31 47 0 0 0 7 40 54 15 29 377 0.08 0.17 45 4,48102039000 Buffalo Creek near Hampden Sydney, VA 102 25 39 28 57 25 16 12 12 4 1 31 352 0.04 0.08 5 8,39802039500 Appomattox River at Farmville, VA 41 18 2 10 19 0 3 14 5 0 0 4 116 0.03 0.06 37 4,57502040000 Appomattox River at Mattoax, VA 177 53 4 14 37 65 65 66 81 61 109 107 839 0.10 0.16 9 8,39302040892 Appomattox River at Route 602 near Mannboro, VA 0 0 0 0 0 0 0 0 0 0 0 0 0 0.00 0.00 3 81502041000 Deep Creek near Mannboro, VA 80 18 2 0 12 2 0 6 20 20 30 31 221 0.03 0.06 2 8,39302041650 Appomattox River at Matoaca, VA 25 0 0 0 7 0 0 1 4 11 0 8 56 0.01 0.03 4 4,84502042500 Chickahominy River near Providence Forge, VA 42 9 2 0 8 0 0 2 4 1 0 8 76 0.01 0.04 14 6,09402044500 Nottoway River near Rawlings, VA 22 7 5 6 14 10 8 12 5 4 0 0 93 0.02 0.03 6 4,47802045500 Nottoway River near Stony Creek, VA 70 12 5 14 22 44 59 75 31 36 36 38 442 0.05 0.06 16 8,39202046000 Stony Creek near Dinwiddie, VA 30 2 10 0 1 28 18 11 17 36 2 6 161 0.04 0.04 40 4,37402047000 Nottoway River near Sebrell, VA 5 2 14 3 3 25 19 10 7 0 0 0 88 0.02 0.01 11 4,72602047500 Blackwater River near Dendron, VA 32 24 16 0 2 4 3 1 6 6 12 20 126 0.02 0.04 7 8,39802049500 Blackwater River near Franklin, VA 0 2 0 2 0 3 1 5 39 19 8 0 79 0.01 0.00 108 5,99102051000 North Meherrin River near Lunenburg, VA 64 13 0 15 21 0 6 0 15 36 38 29 237 0.04 0.08 44 5,71802051500 Meherrin River near Lawrenceville, VA 89 46 16 33 17 40 42 8 30 1 8 33 363 0.06 0.11 24 6,20802052000 Meherrin River at Emporia, VA 8 0 0 0 13 0 27 2 0 2 0 16 68 0.02 0.02 4 4,47802053800 South Fork Roanoke River near Shawsville, VA 100 47 11 2 5 0 0 5 7 15 1 48 241 0.03 0.09 9 8,40002054500 Roanoke River at Lafayette, VA 34 13 0 0 0 1 0 1 4 0 1 14 68 0.01 0.05 11 4,63402054530 Roanoke River at Glenvar, VA 71 19 16 2 8 27 2 1 0 0 0 30 176 0.02 0.06 14 7,91102055000 Roanoke River at Roanoke, VA 5 16 0 0 0 0 0 6 5 0 4 14 50 0.01 0.03 10 4,74602055100 Tinker Creek near Daleville, VA 35 1 0 7 0 2 2 10 8 50 21 3 139 0.02 0.03 21 6,19302056000 Roanoke River at Niagara, VA 0 2 0 5 2 0 0 0 6 6 0 0 21 0.00 0.00 19 4,61302056650 Back Creek near Dundee, VA 63 19 1 0 0 0 4 2 3 18 6 16 132 0.03 0.09 30 4,38202056900 Blackwater River near Rocky Mount, VA 67 21 2 2 9 0 6 1 15 2 0 16 141 0.03 0.09 4 4,52802058400 Pigg River near Sandy Level, VA 73 10 5 2 0 15 6 0 1 2 11 24 149 0.03 0.07 10 5,83702059485 Goose Creek at Rt 747 near Bunker Hill, VA 37 2 0 0 24 30 16 0 0 22 8 13 152 0.07 0.10 19 2,18102059500 Goose Creek near Huddleston, VA 68 22 6 2 9 6 15 29 5 2 2 32 198 0.05 0.11 37 4,32002060500 Roanoke River at Altavista, VA 8 0 0 0 11 3 19 2 2 0 0 0 45 0.01 0.00 16 8,39002061000 Big Otter River near Bedford, VA 28 2 0 0 0 2 0 13 26 30 0 9 110 0.05 0.07 21 2,23802061500 Big Otter River near Evington, VA 60 20 3 5 11 16 10 23 18 13 5 25 209 0.05 0.09 5 4,48502062500 Roanoke (Staunton) River at Brookneal, VA 66 34 35 23 19 41 58 21 11 6 23 25 362 0.06 0.08 87 6,57302064000 Falling River near Naruna, VA 105 55 39 11 44 35 18 39 10 34 19 68 477 0.06 0.11 13 8,39902065500 Cub Creek at Phenix, VA 93 10 1 12 31 30 30 5 25 1 0 16 254 0.05 0.09 8 5,41602066000 Roanoke (Staunton) River at Randolph, VA 15 9 2 2 2 2 10 3 8 1 6 5 65 0.01 0.02 36 6,657
72 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013 Table 13. Number of days with estimated and qualified flows for streamgages in Virginia, water years 1991–2013.—Continued [A:e, National Water Information System (NWIS) remark code indicating that a daily flow value was estimated; A:1, NWIS remark code indicating that a daily flow value was write-protected without a remark code; VA, Virginia; Rt, Route] Streamgage number Streamgage name Estimated (A:e) Write-protected (A:1) Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Total Percentage estimated overall Percentage estimated during winter Total Total daily values 02069700 South Mayo River near Nettleridge, VA 67 13 5 5 6 30 56 2 10 2 2 15 213 0.05 0.08 7 4,577 02070000 North Mayo River near Spencer, VA 57 9 1 1 0 0 2 2 5 2 0 12 91 0.02 0.07 4 4,381 02071530 Smith River at Smith Riv Church near Woolwine, VA 58 5 0 0 0 0 10 0 21 17 14 14 139 0.02 0.05 28 5,893 02072000 Smith River near Philpott, VA 3 1 8 0 2 6 2 2 8 9 0 6 47 0.01 0.01 18 5,838 02072500 Smith River at Bassett, VA 0 12 6 26 28 20 5 5 0 2 0 1 105 0.02 0.01 41 6,559 02073000 Smith River at Martinsville, VA 0 0 1 0 1 1 5 1 1 2 0 0 12 0.00 0.00 7 4,262 02074500 Sandy River near Danville, VA 106 26 21 30 14 3 29 32 7 35 31 51 385 0.05 0.09 7 8,399 02075045 Dan River at Stp near Danville, VA 45 16 6 1 5 5 20 24 1 11 0 7 141 0.02 0.05 47 6,102 02075500 Dan River at Paces, VA 2 6 0 8 18 9 0 3 2 3 2 2 55 0.01 0.01 32 6,573 02077000 Banister River at Halifax, VA 73 29 8 9 25 64 92 118 107 83 68 57 733 0.09 0.08 38 8,009 02077500 Hyco River near Denniston, VA 28 17 12 21 11 13 0 0 3 15 3 22 145 0.02 0.04 38 6,202 02079640 Allen Creek near Boydton, VA 81 15 2 45 41 98 82 54 68 100 167 63 816 0.12 0.09 9 6,951 03164000 New River near Galax, VA 157 37 16 9 2 10 33 17 6 0 2 52 341 0.05 0.14 9 6,934 03165000 Chestnut Creek at Galax, VA 106 20 0 0 0 2 4 7 17 0 0 31 187 0.03 0.10 61 6,209 03165500 New River at Ivanhoe, VA 18 11 0 5 31 20 31 16 0 3 4 7 146 0.03 0.02 16 5,828 03167000 Reed Creek at Grahams Forge, VA 26 5 4 2 0 1 2 8 10 1 0 13 72 0.02 0.04 27 4,633 03168000 New River at Allisonia, VA 46 12 3 4 0 9 9 3 0 3 3 6 98 0.01 0.04 28 6,938 03170000 Little River at Graysontown, VA 52 12 0 0 0 5 0 0 0 0 0 31 100 0.02 0.08 5 4,745 03171000 New River at Radford, VA 3 3 0 0 0 0 1 0 2 0 7 3 19 0.00 0.01 33 6,929 03173000 Walker Creek at Bane, VA 59 12 0 5 0 2 1 0 0 0 0 23 102 0.01 0.05 12 6,936 03175500 Wolf Creek near Narrows, VA 43 10 0 0 0 0 0 17 9 7 0 19 105 0.02 0.04 12 6,570 03176500 New River at Glen Lyn, VA 6 0 0 2 6 2 7 3 3 0 0 0 29 0.00 0.00 13 6,936 03177710 Bluestone River at Falls Mills, VA 18 13 8 2 3 1 4 0 0 0 3 12 64 0.01 0.04 11 4,637 03207800 Levisa Fork at Big Rock, VA 43 9 5 0 9 0 26 21 19 9 0 27 168 0.02 0.05 42 6,938 03208500 Russell Fork at Haysi, VA 69 24 0 0 16 3 4 5 1 0 0 28 150 0.02 0.07 143 6,937 03208950 Cranes Nest River near Clintwood, VA 60 29 4 6 0 0 2 4 56 48 42 55 306 0.04 0.07 130 8,400 03209000 Pound River below Flannagan Dam, near Haysi, VA 0 0 0 0 0 0 0 11 5 0 0 0 16 0.00 0.00 12 6,937 03471500 South Fork Holston River at Riverside, near Chilhowie, VA 25 0 0 0 0 0 0 0 3 0 0 14 42 0.01 0.03 19 6,203 03473000 South Fork Holston River near Damascus, VA 46 5 0 0 0 5 2 1 3 2 0 16 80 0.01 0.04 38 6,203 03474000 Middle Fork Holston River at Seven Mile Ford, VA 16 5 0 2 0 0 0 1 2 0 0 5 31 0.01 0.02 40 6,187 03475000 Middle Fork Holston River near Meadowview, VA 49 14 2 0 8 3 3 0 2 0 0 19 100 0.02 0.05 57 6,203 03478400 Beaver Creek at Bristol, VA 7 6 0 0 0 0 0 0 0 2 1 0 16 0.00 0.01 43 6,203 03488000 North Fork Holston River near Saltville, VA 54 13 0 0 2 5 0 5 2 0 0 22 103 0.02 0.06 74 6,209 03490000 North Fork Holston River near Gate City, VA 0 0 0 0 0 0 0 0 0 0 0 0 0 0.00 0.00 3 264 03524000 Clinch River at Cleveland, VA 58 9 3 8 6 4 11 0 9 3 3 16 130 0.02 0.05 87 6,574 03524500 Guest River at Coeburn, VA 0 0 0 0 0 0 0 0 0 0 0 0 0 0.00 0.00 119

03527000 Clinch River at Speers Ferry, VA 15 0 0 0 0 0 2 0 26 9 1 3 56 0.01 0.02 48 4,38103529500 Powell River at Big Stone Gap, VA 9 0 1 0 0 0 0 0 2 3 5 5 25 0.01 0.01 62 4,38103531500 Powell River near Jonesville, VA 25 1 0 2 0 0 0 4 1 3 0 7 43 0.01 0.02 83 6,572

Total 9,953 4,160 1,373 1,111 1,551 1,750 2,152 2,063 2,518 2,807 2,373 3,785 35,596 0.04 0.07 4,398 969,759
Table 19 73

Table 19. Number of comparisons of directly measured flow to the rating in effect at the time of measurement relative to 

divergence thresholds for streamgages in Virginia, water years 1991–2013.—Continued

[∆Q, incidents of difference in flow; %, percent; >, greater than; <, less than; unexplained, lacking an explanation or description of measurement quality in 

National Water Information System; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name

Number of 

measurementrating 

comparisons

Number, 

∆Q > 8%

Number, 

∆Q > 8%, 

unexplained

Number, 

5% > ∆Q < 8%

Number, 

5% > ∆Q < 8%, 

unexplained

Percentage of 

unexplained 

∆Qs

01613900 Hogue Creek near Hayfield, VA 85 2 0 10 1 0.01

01615000 Opequon Creek near Berryville, VA 145 9 2 19 2 0.03

01616100 Dry Marsh Run near Berryville, VA 82 6 3 19 0 0.04

01620500 North River near Stokesville, VA 95 10 4 23 0 0.04

01621050 Muddy Creek at Mount Clinton, VA 123 10 4 30 2 0.05

01622000 North River near Burketown, VA 79 1 1 3 1 0.03

01625000 Middle River near Grottoes, VA 160 2 1 6 0 0.01

01626000 South River near Waynesboro, VA 166 1 0 10 1 0.01

01626850 South River near Dooms, VA 120 3 0 6 0 0.00

01627500 South River at Harriston, VA 98 2 0 6 0 0.00

01628500 South Fork Shenandoah River near Lynnwood, VA 155 2 0 8 1 0.01

01629500 South Fork Shenandoah River near Luray, VA 86 1 0 9 0 0.00

01631000 South Fork Shenandoah River at Front Royal, VA 93 5 0 20 1 0.01

01632000 North Fork Shenandoah River at Cootes Store, VA 119 9 1 28 1 0.02

01632082 Linville Creek at Broadway, VA 190 7 0 16 3 0.02

01632900 Smith Creek near New Market, VA 190 1 0 7 0 0.00

01633000 North Fork Shenandoah River at Mount Jackson, VA 88 1 1 3 2 0.03

01634000 North Fork Shenandoah River near Strasburg, VA 137 6 2 17 1 0.02

01634500 Cedar Creek near Winchester, VA 178 9 0 19 3 0.02

01635500 Passage Creek near Buckton, VA 155 9 2 26 2 0.03

01636316 Spout Run at Rt 621 near Millwood, VA 82 2 1 10 0 0.01

01636690 Piney Run near Lovettsville, VA 86 11 5 18 2 0.08

01638350 South Fork Catoctin Creek at Rt 698 near Waterford, VA 92 7 1 23 0 0.01

01638420 North Fork Catoctin Creek at Rt 681 near Waterford, VA 88 6 2 13 1 0.03

01638480 Catoctin Creek at Taylorstown, VA 99 7 3 10 2 0.05

01643590 Limestone Branch near Leesburg, VA 93 5 2 16 1 0.03

01643700 Goose Creek near Middleburg, VA 89 8 3 16 1 0.04

01643805 North Fork Goose Creek at Rt 729 near Lincoln, VA 93 5 0 17 1 0.01

01643880 Beaverdam Creek at Rt 734 near Mountville, VA 89 8 0 17 4 0.04

01644000 Goose Creek near Leesburg, VA 98 4 1 10 0 0.01

01644280 Broad Run near Leesburg, VA 83 9 4 18 0 0.05

01645704 Difficult Run above Fox Lake near Fairfax, VA 61 9 1 13 0 0.02

01645762 South Fork Little Difficult Run above Mouth near Vienna, VA 60 9 2 14 0 0.03

01646000 Difficult Run near Great Falls, VA 181 10 4 20 2 0.03

01646305 Dead Run at Whann Avenue near Mclean, VA 56 14 3 18 0 0.05

01652500 Fourmile Run at Alexandria, VA 120 8 2 16 1 0.03

01653000 Cameron Run at Alexandria, VA 136 10 6 21 6 0.09

01654000 Accotink Creek near Annandale, VA 95 5 2 19 3 0.05

01656000 Cedar Run near Catlett, VA 171 9 2 16 1 0.02

01656903 Flatlick Branch above Frog Branch at Chantilly, VA 63 12 2 15 1 0.05

01658500 South Fork Quantico Creek near Independent Hill, VA 158 25 5 44 4 0.06

01660400 Aquia Creek near Garrisonville, VA 122 16 2 32 5 0.06

01662800 Battle Run near Laurel Mills, VA 163 6 3 17 4 0.04

01663500 Hazel River at Rixeyville, VA 95 1 1 17 0 0.01

01664000 Rappahannock River at Remington, VA 90 6 2 19 0 0.02

01665500 Rapidan River near Ruckersville, VA 124 0 0 7 2 0.02

01666500 Robinson River near Locust Dale, VA 198 2 1 7 0 0.01

01667500 Rapidan River near Culpeper, VA 94 3 1 7 1 0.02

01668000 Rappahannock River near Fredericksburg, VA 81 11 4 19 0 0.05

01669000 Piscataway Creek near Tappahannock, VA 87 2 1 7 1 0.02
74 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

Table 19. Number of comparisons of directly measured flow to the rating in effect at the time of measurement relative to 

divergence thresholds for streamgages in Virginia, water years 1991–2013.—Continued

[∆Q, incidents of difference in flow; %, percent; >, greater than; <, less than; unexplained, lacking an explanation or description of measurement quality in 

National Water Information System; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name

Number of 

measurementrating 

comparisons

Number, 

∆Q > 8%

Number, 

∆Q > 8%, 

unexplained

Number, 

5% > ∆Q < 8%

Number, 

5% > ∆Q < 8%, 

unexplained

Percentage of 

unexplained 

∆Qs

01669520 Dragon Swamp at Mascot, VA 83 2 0 3 0 0.00

01670400 North Anna River near Partlow, VA 96 5 1 16 2 0.03

01671020 North Anna River at Hart Corner near Doswell, VA 137 3 1 12 5 0.04

01671025 North Anna River above Little River near Doswell, VA 75 8 5 34 3 0.11

01671100 Little River near Doswell, VA 84 1 1 5 0 0.01

01672500 South Anna River near Ashland, VA 88 5 2 16 0 0.02

01673000 Pamunkey River near Hanover, VA 134 5 3 24 0 0.02

01673550 Totopotomoy Creek near Studley, VA 195 10 2 22 10 0.06

01673800 Po River near Spotsylvania, VA 169 7 6 19 2 0.05

01674000 Mattaponi River near Bowling Green, VA 163 27 19 32 0 0.12

01674500 Mattaponi River near Beulahville, VA 139 6 3 17 0 0.02

02011400 Jackson River near Bacova, VA 148 4 3 6 1 0.03

02011460 Back Creek near Sunrise, VA 97 3 1 8 1 0.02

02011470 Back Creek at Sunrise, VA 176 10 6 25 6 0.07

02011490 Little Back Creek near Sunrise, VA 31 6 4 7 0 0.13

02011500 Back Creek near Mountain Grove, VA 161 8 3 16 2 0.03

02011800 Jackson River below Gathright Dam near Hot Spgs, VA 205 21 12 45 4 0.08

02013000 Dunlap Creek near Covington, VA 155 3 2 14 1 0.02

02013100 Jackson River below Dunlap Creek at Covington, VA 151 2 1 12 5 0.04

02014000 Potts Creek near Covington, VA 151 5 4 12 1 0.03

02015700 Bullpasture River at Williamsville, VA 101 1 0 4 2 0.02

02016000 Cowpasture River near Clifton Forge, VA 108 3 1 8 1 0.02

02016500 James River at Lick Run, VA 124 2 1 5 2 0.02

02017500 Johns Creek at New Castle, VA 82 3 0 6 1 0.01

02018000 Craig Creek at Parr, VA 102 0 0 4 0 0.00

02018500 Catawba Creek near Catawba, VA 83 4 2 10 0 0.02

02019500 James River at Buchanan, VA 119 0 0 2 0 0.00

02020500 Calfpasture River above Mill Creek at Goshen, VA 108 1 0 5 0 0.00

02021500 Maury River at Rockbridge Baths, VA 111 3 1 27 5 0.05

02022500 Kerrs Creek near Lexington, VA 92 4 3 12 3 0.07

02024000 Maury River near Buena Vista, VA 91 1 1 13 0 0.01

02024752 James River at Blue Ridge Pkwy near Big Island, VA 42 1 1 8 0 0.02

02024915 Pedlar River at Forest Road near Buena Vista, VA 74 0 0 8 1 0.01

02025500 James River at Holcomb Rock, VA 83 10 6 18 0 0.07

02026000 James River at Bent Creek, VA 57 3 1 10 0 0.02

02027000 Tye River near Lovingston, VA 106 2 2 5 2 0.04

02027500 Piney River at Piney River, VA 86 1 1 3 2 0.03

02028500 Rockfish River near Greenfield, VA 109 1 1 9 2 0.03

02029000 James River at Scottsville, VA 96 1 0 15 0 0.00

02030000 Hardware River below Briery Run near Scottsville, VA 127 2 2 15 5 0.06

02030500 Slate River near Arvonia, VA 119 1 0 7 1 0.01

02031000 Mechums River near White Hall, VA 97 3 1 8 1 0.02

02032250 Moormans River near Free Union, VA 73 5 2 9 1 0.04

02032640 North Fork Rivanna River near Earlysville, VA 168 11 8 21 5 0.08

02034000 Rivanna River at Palmyra, VA 90 3 1 8 3 0.04

02035000 James River at Cartersville, VA 178 29 19 45 4 0.13

02036500 Fine Creek at Fine Creek Mills, VA 165 10 7 25 2 0.05

02037000 James River And Kanawha Canal near Richmond, VA 117 6 0 8 1 0.01

02037500 James River near Richmond, VA 110 5 0 11 1 0.01

02038850 Holiday Creek near Andersonville, VA 94 6 3 26 0 0.03
Table 19 75

Table 19. Number of comparisons of directly measured flow to the rating in effect at the time of measurement relative to 

divergence thresholds for streamgages in Virginia, water years 1991–2013.—Continued

[∆Q, incidents of difference in flow; %, percent; >, greater than; <, less than; unexplained, lacking an explanation or description of measurement quality in 

National Water Information System; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name

Number of 

measurementrating 

comparisons

Number, 

∆Q > 8%

Number, 

∆Q > 8%, 

unexplained

Number, 

5% > ∆Q < 8%

Number, 

5% > ∆Q < 8%, 

unexplained

Percentage of 

unexplained 

∆Qs

02039000 Buffalo Creek near Hampden Sydney, VA 164 3 1 4 1 0.01

02039500 Appomattox River at Farmville, VA 89 1 1 8 1 0.02

02040000 Appomattox River at Mattoax, VA 160 2 1 17 3 0.03

02040892 Appomattox River at Route 602 near Mannboro, VA 30 2 0 3 0 0.00

02041000 Deep Creek near Mannboro, VA 170 6 3 14 3 0.04

02041650 Appomattox River at Matoaca, VA 95 5 3 19 0 0.03

02042500 Chickahominy River near Providence Forge, VA 145 12 6 32 1 0.05

02044500 Nottoway River near Rawlings, VA 94 2 0 11 1 0.01

02045500 Nottoway River near Stony Creek, VA 175 3 2 11 3 0.03

02046000 Stony Creek near Dinwiddie, VA 88 2 2 8 2 0.05

02047000 Nottoway River near Sebrell, VA 94 4 2 18 0 0.02

02047500 Blackwater River near Dendron, VA 166 31 2 38 3 0.03

02049500 Blackwater River near Franklin, VA 136 29 3 40 0 0.02

02051000 North Meherrin River near Lunenburg, VA 122 8 4 17 4 0.07

02051500 Meherrin River near Lawrenceville, VA 129 9 1 21 4 0.04

02052000 Meherrin River at Emporia, VA 88 7 2 9 1 0.03

02053800 South Fork Roanoke River near Shawsville, VA 169 6 3 12 2 0.03

02054500 Roanoke River at Lafayette, VA 89 1 0 9 4 0.04

02054530 Roanoke River at Glenvar, VA 160 2 1 8 5 0.04

02055000 Roanoke River at Roanoke, VA 103 5 5 7 1 0.06

02055100 Tinker Creek near Daleville, VA 135 7 5 13 2 0.05

02056000 Roanoke River at Niagara, VA 89 2 1 3 1 0.02

02056650 Back Creek near Dundee, VA 88 0 0 8 4 0.05

02056900 Blackwater River near Rocky Mount, VA 83 2 1 5 1 0.02

02058400 Pigg River near Sandy Level, VA 114 3 2 17 1 0.03

02059485 Goose Creek at Rt 747 near Bunker Hill, VA 47 0 0 1 1 0.02

02059500 Goose Creek near Huddleston, VA 88 2 0 7 1 0.01

02060500 Roanoke River at Altavista, VA 160 3 3 23 4 0.04

02061000 Big Otter River near Bedford, VA 51 5 4 8 1 0.10

02061500 Big Otter River near Evington, VA 95 1 0 4 1 0.01

02062500 Roanoke (Staunton) River at Brookneal, VA 134 8 1 19 1 0.01

02064000 Falling River near Naruna, VA 161 3 1 8 1 0.01

02065500 Cub Creek at Phenix, VA 110 6 2 7 1 0.03

02066000 Roanoke (Staunton) River at Randolph, VA 138 12 5 26 2 0.05

02069700 South Mayo River near Nettleridge, VA 84 2 1 6 2 0.04

02070000 North Mayo River near Spencer, VA 78 2 1 6 2 0.04

02071530 Smith River at Smith Riv Church near Woolwine, VA 117 4 1 13 8 0.08

02072000 Smith River near Philpott, VA 116 4 1 13 3 0.03

02072500 Smith River at Bassett, VA 140 3 1 17 1 0.01

02073000 Smith River at Martinsville, VA 71 2 1 5 0 0.01

02074500 Sandy River near Danville, VA 158 2 1 7 0 0.01

02075045 Dan River at Stp near Danville, VA 122 10 1 24 0 0.01

02075500 Dan River at Paces, VA 132 14 3 21 0 0.02

02077000 Banister River at Halifax, VA 102 20 9 32 1 0.10

02077500 Hyco River near Denniston, VA 122 5 0 13 0 0.00

02079640 Allen Creek near Boydton, VA 153 8 4 20 1 0.03

03164000 New River near Galax, VA 143 2 1 6 1 0.01

03165000 Chestnut Creek at Galax, VA 134 5 4 9 1 0.04

03165500 New River at Ivanhoe, VA 123 3 3 8 2 0.04

03167000 Reed Creek at Grahams Forge, VA 102 0 0 0 0 0.00
76 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

Table 19. Number of comparisons of directly measured flow to the rating in effect at the time of measurement relative to 

divergence thresholds for streamgages in Virginia, water years 1991–2013.—Continued

[∆Q, incidents of difference in flow; %, percent; >, greater than; <, less than; unexplained, lacking an explanation or description of measurement quality in 

National Water Information System; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name

Number of 

measurementrating 

comparisons

Number, 

∆Q > 8%

Number, 

∆Q > 8%, 

unexplained

Number, 

5% > ∆Q < 8%

Number, 

5% > ∆Q < 8%, 

unexplained

Percentage of 

unexplained 

∆Qs

03168000 New River at Allisonia, VA 134 1 1 9 4 0.04

03170000 Little River at Graysontown, VA 110 2 0 6 1 0.01

03171000 New River at Radford, VA 128 3 1 10 1 0.02

03173000 Walker Creek at Bane, VA 155 6 1 17 5 0.04

03175500 Wolf Creek near Narrows, VA 146 3 1 9 2 0.02

03176500 New River at Glen Lyn, VA 149 3 1 9 0 0.01

03177710 Bluestone River at Falls Mills, VA 129 10 9 29 14 0.18

03207800 Levisa Fork at Big Rock, VA 151 0 0 7 3 0.02

03208500 Russell Fork at Haysi, VA 151 3 1 9 0 0.01

03208950 Cranes Nest River near Clintwood, VA 186 21 11 29 2 0.07

03209000 Pound River below Flannagan Dam, near Haysi, VA 140 5 2 9 1 0.02

03471500 South Fork Holston River at Riverside, near Chilhowie, VA 142 5 3 7 0 0.02

03473000 South Fork Holston River near Damascus, VA 126 2 1 10 3 0.03

03474000 Middle Fork Holston River at Seven Mile Ford, VA 135 6 3 18 0 0.02

03475000 Middle Fork Holston River near Meadowview, VA 140 2 1 9 2 0.02

03478400 Beaver Creek at Bristol, VA 163 4 4 16 8 0.07

03488000 North Fork Holston River near Saltville, VA 144 3 0 4 0 0.00

03490000 North Fork Holston River near Gate City, VA 5 1 0 1 0 0.00

03524000 Clinch River at Cleveland, VA 149 1 1 4 1 0.01

03524500 Guest River at Coeburn, VA 2 0 0 0 0 0.00

03527000 Clinch River at Speers Ferry, VA 101 0 0 7 2 0.02

03529500 Powell River at Big Stone Gap, VA 109 3 2 7 1 0.03

03531500 Powell River near Jonesville, VA 138 1 1 4 0 0.01

0165389205 Accotink Creek near Ranger Road at Fairfax, VA 20 2 1 6 0 0.05

Total 20,380 1,063 451 2,482 287 0.04
Table 21 77

Table 21. Number of days of available Qprev record for streamgages in Virginia, by streamgage and month, and earliest date the records are available, during water years 1991–2013.—Continued[Qprev, the flow value from the shifted rating table in effect at the time of the previous flow measurement that corresponds to the gage height of each day’s daily flow value; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name Earliest date Number of daily observations of Qprev , by month Total daily observations Total, in years Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

01613900 Hogue Creek near Hayfield, VA 11/27/2001 372 339 372 360 372 360 372 372 360 341 334 372 4,326 11.801615000 Opequon Creek near Berryville, VA 11/28/1990 558 509 558 540 558 540 558 558 540 515 483 549 6,466 17.701616100 Dry Marsh Run near Berryville, VA 9/5/2002 341 311 341 330 341 330 341 341 356 341 330 341 4,044 11.101620500 North River near Stokesville, VA 10/3/2001 372 339 372 360 372 360 372 372 360 370 360 372 4,381 12.001621050 Muddy Creek at Mount Clinton, VA 1/28/1997 500 480 527 510 527 510 527 527 510 496 480 496 6,090 16.701622000 North River near Burketown, VA 10/5/2001 372 339 372 360 372 360 372 372 360 368 360 372 4,379 12.001625000 Middle River near Grottoes, VA 12/3/1990 713 650 713 690 713 690 713 713 690 682 660 711 8,338 22.801626000 South River near Waynesboro, VA 12/3/1990 713 650 713 690 713 690 713 713 690 682 660 711 8,338 22.801626850 South River near Dooms, VA 12/3/1990 434 396 434 420 434 420 434 434 420 421 420 442 5,109 14.001627500 South River at Harriston, VA 2/2/2001 372 366 403 390 403 390 403 403 390 372 360 372 4,624 12.701628500 South Fork Shenandoah River near Lynnwood, VA 12/3/1990 713 650 713 690 713 690 713 713 690 682 660 711 8,338 22.801629500 South Fork Shenandoah River near Luray, VA 10/12/2001 372 339 372 360 372 360 372 372 360 361 360 372 4,372 12.001631000 South Fork Shenandoah River at Front Royal, VA 10/5/2001 372 339 372 360 372 360 372 372 360 368 360 372 4,379 12.001632000 North Fork Shenandoah River at Cootes Store, VA 4/22/1997 496 452 496 489 527 510 527 527 510 496 480 496 6,006 16.401632082 Linville Creek at Broadway, VA 11/29/1990 713 650 713 690 713 690 713 713 690 682 662 713 8,342 22.801632900 Smith Creek near New Market, VA 11/29/1990 713 650 713 690 713 690 713 713 690 682 662 713 8,342 22.801633000 North Fork Shenandoah River at Mount Jackson, VA 5/9/2001 372 339 372 360 395 390 403 403 390 372 360 372 4,528 12.401634000 North Fork Shenandoah River near Strasburg, VA 12/12/1996 527 480 527 510 527 510 527 527 510 496 480 516 6,137 16.801634500 Cedar Creek near Winchester, VA 11/29/1990 713 650 713 690 713 690 713 713 690 682 662 713 8,342 22.801635500 Passage Creek near Buckton, VA 11/29/1990 713 650 713 690 713 690 713 713 690 682 662 713 8,342 22.801636316 Spout Run at Rt 621 near Millwood, VA 10/18/2002 341 311 341 330 341 330 341 341 330 324 330 341 4,001 11.001636690 Piney Run near Lovettsville, VA 11/28/2001 372 339 372 360 372 360 372 372 360 341 333 372 4,325 11.801638350 South Fork Catoctin Creek at Rt 698 near Waterford, VA 9/6/2001 372 339 372 360 372 360 372 372 385 372 360 372 4,408 12.101638420 North Fork Catoctin Creek at Rt 681 near Waterford, VA 9/6/2001 372 339 372 360 372 360 372 372 385 372 360 372 4,408 12.101638480 Catoctin Creek at Taylorstown, VA 11/5/2001 372 339 372 360 372 360 372 372 360 341 356 372 4,348 11.901643590 Limestone Branch near Leesburg, VA 9/21/2001 372 339 372 360 372 360 372 372 370 372 360 372 4,393 12.001643700 Goose Creek near Middleburg, VA 9/7/2001 372 339 372 360 372 360 372 372 384 367 360 372 4,402 12.101643805 North Fork Goose Creek at Rt 729 near Lincoln, VA 10/9/2001 372 339 372 360 372 360 372 372 360 364 360 372 4,375 12.001643880 Beaverdam Creek at Rt 734 near Mountville, VA 9/6/2001 372 339 372 360 372 360 372 372 385 372 360 372 4,408 12.101644000 Goose Creek near Leesburg, VA 3/19/2001 372 339 385 390 403 390 403 403 390 372 360 372 4,579 12.501644280 Broad Run near Leesburg, VA 4/10/2002 341 311 341 351 372 360 372 372 360 341 330 341 4,192 11.501645704 Difficult Run above Fox Lake near Fairfax, VA 10/25/2007 186 170 186 180 186 180 186 186 180 162 180 186 2,168 5.901645762 South Fork Little Difficult Run above Mouth near Vienna, VA 10/25/2007 186 170 186 180 186 180 186 186 180 162 180 186 2,168 5.901646000 Difficult Run near Great Falls, VA 11/27/1990 713 650 713 690 713 690 713 713 690 682 664 713 8,344 22.801646305 Dead Run at Whann Avenue near Mclean, VA 3/7/2008 155 141 180 180 186 180 186 186 180 155 150 155 2,034 5.601652500 Fourmile Run at Alexandria, VA 10/16/1998 465 424 465 450 465 450 465 465 450 450 450 465 5,464 15.001653000 Cameron Run at Alexandria, VA 12/16/1996 527 480 527 510 527 510 527 527 510 496 480 512 6,133 16.80165389205 Accotink Creek near Ranger Road at Fairfax, VA 2/9/2012 31 49 62 60 62 60 62 62 60 31 30 31 600 1.601654000 Accotink Creek near Annandale, VA 11/26/2001 372 339 372 360 372 360 372 372 360 341 335 372 4,327 11.801656000 Cedar Run near Catlett, VA 11/27/1990 713 650 713 690 713 690 713 713 689 682 664 713 8,343 22.8
78 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013 Table 21. Number of days of available 

Q

prev record for streamgages in Virginia, by streamgage and month, and earliest date the records are available, during water years 

1991–2013.—Continued[Qprev, the flow value from the shifted rating table in effect at the time of the previous flow measurement that corresponds to the gage height of each day’s daily flow value; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name Earliest date Number of daily observations of Qprev , by month Total daily observations Total, in years Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

01656903 Flatlick Branch above Frog Branch at Chantilly, VA 10/24/2007 186 170 186 180 186 180 186 186 180 163 180 186 2,169 5.901658500 South Fork Quantico Creek near Independent Hill, VA 11/25/1996 527 480 527 510 527 510 527 527 510 496 486 527 6,154 16.801660400 Aquia Creek near Garrisonville, VA 1/19/2000 416 396 434 420 434 420 434 434 420 403 390 403 5,004 13.701662800 Battle Run near Laurel Mills, VA 10/11/1990 651 593 651 630 651 630 630 620 600 614 630 651 7,551 20.701663500 Hazel River at Rixeyville, VA 11/1/2001 372 339 372 360 372 360 372 372 360 341 360 372 4,352 11.901664000 Rappahannock River at Remington, VA 11/1/2001 372 339 372 360 372 360 372 372 360 341 360 372 4,352 11.901665500 Rapidan River near Ruckersville, VA 12/9/1998 465 424 465 450 465 450 465 465 450 434 420 457 5,410 14.801666500 Robinson River near Locust Dale, VA 10/15/1990 713 650 713 690 713 690 713 713 690 699 690 713 8,387 23.001667500 Rapidan River near Culpeper, VA 3/23/2001 372 339 381 390 403 390 403 403 390 372 360 372 4,575 12.501668000 Rappahannock River near Fredericksburg, VA 12/18/2000 403 367 403 390 403 390 403 403 390 372 360 386 4,670 12.801669000 Piscataway Creek near Tappahannock, VA 10/2/2001 372 339 372 360 372 360 372 372 360 371 360 372 4,382 12.001669520 Dragon Swamp at Mascot, VA 6/11/2001 372 339 372 360 372 380 403 403 390 372 360 372 4,495 12.301670400 North Anna River near Partlow, VA 11/26/1990 341 311 346 360 372 360 372 372 360 310 305 341 4,150 11.401671020 North Anna River at Hart Corner near Doswell, VA 10/1/1998 465 424 465 450 465 450 465 465 450 465 450 465 5,479 15.001671025 North Anna River above Little River near Doswell, VA 11/10/2004 272 252 260 266 267 260 279 279 265 247 250 259 3,156 8.601671100 Little River near Doswell, VA 9/17/2001 372 339 372 360 372 360 372 372 374 372 360 372 4,397 12.001672500 South Anna River near Ashland, VA 6/10/1997 310 283 310 300 310 321 356 372 360 310 300 310 3,842 10.501673000 Pamunkey River near Hanover, VA 5/7/1997 496 452 496 480 521 510 527 527 510 496 480 496 5,991 16.401673550 Totopotomoy Creek near Studley, VA 11/26/1990 713 650 713 690 713 690 713 713 690 682 665 713 8,345 22.801673800 Po River near Spotsylvania, VA 11/27/1990 713 650 713 690 713 690 713 713 690 682 664 713 8,344 22.801674000 Mattaponi River near Bowling Green, VA 11/26/1990 713 650 713 690 713 690 713 713 690 682 665 713 8,345 22.801674500 Mattaponi River near Beulahville, VA 10/4/1995 559 509 558 540 558 540 558 558 539 555 540 558 6,572 18.002011400 Jackson River near Bacova, VA 11/15/1994 589 537 589 570 589 570 589 589 570 558 556 589 6,895 18.902011460 Back Creek near Sunrise, VA 8/14/2001 372 339 372 360 372 360 372 390 390 372 360 372 4,431 12.102011470 Back Creek at Sunrise, VA 11/15/1994 589 537 589 570 589 570 589 589 570 558 556 589 6,895 18.902011490 Little Back Creek near Sunrise, VA 10/23/2003 310 283 310 300 310 300 310 310 300 288 300 310 3,631 9.902011500 Back Creek near Mountain Grove, VA 11/15/1994 589 537 589 570 589 570 589 589 570 558 556 589 6,895 18.902011800 Jackson River below Gathright Dam near Hot Spgs, VA 11/16/1994 589 537 589 570 589 570 589 589 570 558 555 589 6,894 18.902013000 Dunlap Creek near Covington, VA 10/5/1995 558 509 558 540 558 540 558 558 540 554 540 558 6,571 18.002013100 Jackson River below Dunlap Creek at Covington, VA 8/30/1995 558 509 558 540 558 540 558 560 570 558 540 558 6,607 18.102014000 Potts Creek near Covington, VA 4/6/1995 558 509 558 565 589 570 589 589 570 558 540 558 6,753 18.502015700 Bullpasture River at Williamsville, VA 10/15/1998 465 424 465 450 465 450 465 465 450 451 450 465 5,465 15.002016000 Cowpasture River near Clifton Forge, VA 3/23/2000 403 367 412 420 434 420 434 434 420 403 390 403 4,940 13.502016500 James River at Lick Run, VA 5/18/1998 465 424 465 450 479 480 496 496 480 465 450 465 5,615 15.402017500 Johns Creek at New Castle, VA 12/4/2001 372 339 372 360 372 360 372 372 360 341 330 369 4,319 11.802018000 Craig Creek at Parr, VA 11/5/2001 372 339 372 360 372 360 372 372 360 341 356 372 4,348 11.902018500 Catawba Creek near Catawba, VA 12/4/2001 372 339 372 360 372 360 372 372 360 341 330 369 4,319 11.802019500 James River at Buchanan, VA 7/15/1998 465 424 465 450 465 450 482 496 480 465 450 465 5,557 15.202020500 Calfpasture River above Mill Creek at Goshen, VA 12/8/1998 465 424 465 450 465 450 465 465 450 434 420 458 5,411 14.802021500 Maury River at Rockbridge Baths, VA 1/21/1997 507 480 527 510 527 510 527 527 510 496 480 496 6,097 16.7
Table 21 79

Table 21. Number of days of available Qprev record for streamgages in Virginia, by streamgage and month, and earliest date the records are available, during water years 1991–2013.—Continued[Qprev, the flow value from the shifted rating table in effect at the time of the previous flow measurement that corresponds to the gage height of each day’s daily flow value; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name Earliest date Number of daily observations of Qprev , by month Total daily observations Total, in years Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

02022500 Kerrs Creek near Lexington, VA 5/15/2001 372 339 372 360 389 390 403 403 390 372 360 372 4,522 12.402024000 Maury River near Buena Vista, VA 11/18/1999 434 396 434 420 434 420 434 434 420 403 403 434 5,066 13.902024752 James River at Blue Ridge Pkwy near Big Island, VA 11/17/2006 217 198 217 210 217 210 217 217 210 186 194 217 2,510 6.902024915 Pedlar River at Forest Road near Buena Vista, VA 12/2/2002 341 311 341 330 341 330 341 341 324 296 300 340 3,936 10.802025500 James River at Holcomb Rock, VA 3/30/1999 434 396 436 450 465 450 465 465 450 434 420 434 5,299 14.502026000 James River at Bent Creek, VA 9/19/2003 310 283 310 300 310 300 310 310 312 310 300 310 3,665 10.002027000 Tye River near Lovingston, VA 12/14/1998 465 424 465 450 465 450 465 465 450 434 420 452 5,405 14.802027500 Piney River at Piney River, VA 5/15/2001 372 339 372 360 389 390 403 403 390 372 360 372 4,522 12.402028500 Rockfish River near Greenfield, VA 9/9/1998 465 424 465 450 465 450 465 465 472 465 450 465 5,501 15.102029000 James River at Scottsville, VA 1/14/1997 514 480 527 510 527 510 527 527 510 496 480 496 6,104 16.702030000 Hardware River below Briery Run near Scottsville, VA 11/6/1997 496 452 496 480 496 480 496 496 480 465 475 496 5,808 15.902030500 Slate River near Arvonia, VA 11/27/1990 403 367 403 390 403 390 403 433 420 387 364 403 4,766 13.002031000 Mechums River near White Hall, VA 11/27/2001 372 339 372 360 372 360 372 352 330 333 334 372 4,268 11.702032250 Moormans River near Free Union, VA 7/8/2005 248 226 248 240 248 240 272 279 270 248 240 248 3,007 8.202032640 North Fork Rivanna River near Earlysville, VA 12/10/1993 620 565 620 600 620 600 620 620 600 589 570 611 7,235 19.802034000 Rivanna River at Palmyra, VA 6/29/2001 372 339 372 360 372 362 403 403 390 372 360 372 4,477 12.302035000 James River at Cartersville, VA 11/29/1990 713 650 713 690 713 690 713 713 690 682 662 713 8,342 22.802036500 Fine Creek at Fine Creek Mills, VA 12/3/1990 713 650 713 690 713 690 713 713 690 682 660 711 8,338 22.802037000 James River And Kanawha Canal near Richmond, VA 5/3/2001 372 339 372 360 401 390 403 403 390 372 360 372 4,534 12.402037500 James River near Richmond, VA 1/6/1998 491 452 496 480 496 480 496 496 480 465 450 465 5,747 15.702038850 Holiday Creek near Andersonville, VA 8/10/2001 372 339 372 360 372 360 372 394 390 372 360 372 4,435 12.102039000 Buffalo Creek near Hampden Sydney, VA 12/5/1990 713 650 713 690 713 690 713 713 690 682 660 709 8,336 22.802039500 Appomattox River at Farmville, VA 5/18/2001 372 339 372 360 386 390 403 403 390 372 360 372 4,519 12.402040000 Appomattox River at Mattoax, VA 12/3/1990 713 650 713 690 713 690 713 713 690 682 660 711 8,338 22.802040892 Appomattox River at Route 602 near Mannboro, VA 9/27/2011 62 57 62 60 62 60 62 62 64 62 60 62 735 2.002041000 Deep Creek near Mannboro, VA 12/3/1990 713 650 713 690 713 690 713 712 690 682 660 711 8,337 22.802041650 Appomattox River at Matoaca, VA 7/26/2000 403 367 403 390 403 390 409 430 420 403 390 403 4,811 13.202042500 Chickahominy River near Providence Forge, VA 2/26/1997 496 455 527 510 527 510 515 521 510 496 480 496 6,043 16.502044500 Nottoway River near Rawlings, VA 8/7/2001 372 339 372 360 372 360 372 397 390 372 360 372 4,438 12.202045500 Nottoway River near Stony Creek, VA 12/4/1990 713 650 713 690 713 690 713 713 690 682 660 710 8,337 22.802046000 Stony Creek near Dinwiddie, VA 12/11/2001 372 339 372 360 372 360 372 372 360 341 330 362 4,312 11.802047000 Nottoway River near Sebrell, VA 12/13/2000 403 367 403 390 403 390 403 403 387 372 360 391 4,672 12.802047500 Blackwater River near Dendron, VA 11/28/1990 709 650 713 690 713 667 687 713 686 636 633 690 8,187 22.402049500 Blackwater River near Franklin, VA 6/10/1997 496 452 496 480 496 501 527 527 510 496 480 496 5,957 16.302051000 North Meherrin River near Lunenburg, VA 2/12/1998 465 441 496 480 496 480 496 496 480 465 450 465 5,710 15.602051500 Meherrin River near Lawrenceville, VA 3/6/1997 496 452 522 510 527 510 527 527 510 496 480 496 6,053 16.602052000 Meherrin River at Emporia, VA 8/7/2001 372 339 372 360 372 360 372 397 390 372 360 372 4,438 12.202053800 South Fork Roanoke River near Shawsville, VA 10/23/1990 713 650 713 690 713 690 713 713 690 691 690 713 8,379 22.902054500 Roanoke River at Lafayette, VA 3/20/2001 372 339 384 390 403 390 403 403 390 372 360 372 4,578 12.502054530 Roanoke River at Glenvar, VA 4/21/1992 651 593 651 640 682 660 682 682 660 651 630 651 7,833 21.4
80 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013 Table 21. Number of days of available 

Q

prev record for streamgages in Virginia, by streamgage and month, and earliest date the records are available, during water years 

1991–2013.—Continued[Qprev, the flow value from the shifted rating table in effect at the time of the previous flow measurement that corresponds to the gage height of each day’s daily flow value; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name Earliest date Number of daily observations of Qprev , by month Total daily observations Total, in years Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

02055000 Roanoke River at Roanoke, VA 11/20/2000 403 367 403 390 403 390 403 403 390 372 371 403 4,698 12.902055100 Tinker Creek near Daleville, VA 11/13/1996 527 480 527 510 527 510 527 527 510 496 498 527 6,166 16.902056000 Roanoke River at Niagara, VA 4/10/2001 372 339 372 381 403 390 403 403 390 372 360 372 4,557 12.502056650 Back Creek near Dundee, VA 11/7/2001 372 339 372 360 372 360 372 372 360 341 354 372 4,346 11.902056900 Blackwater River near Rocky Mount, VA 6/20/2001 372 339 372 360 372 371 403 403 390 372 360 372 4,486 12.302058400 Pigg River near Sandy Level, VA 11/7/1997 496 452 496 480 496 480 496 496 480 465 474 496 5,807 15.902059485 Goose Creek at Rt 747 near Bunker Hill, VA 11/28/2007 186 170 186 180 186 180 186 186 180 155 153 186 2,134 5.802059500 Goose Creek near Huddleston, VA 1/28/2002 345 339 372 360 372 360 372 372 360 341 330 341 4,264 11.702060500 Roanoke River at Altavista, VA 11/15/1990 713 650 713 690 713 690 713 713 690 682 676 713 8,356 22.902061000 Big Otter River near Bedford, VA 10/11/2007 186 170 186 180 186 180 186 186 180 176 180 186 2,182 6.002061500 Big Otter River near Evington, VA 8/2/2001 372 339 372 360 372 360 372 402 390 372 360 372 4,443 12.202062500 Roanoke (Staunton) River at Brookneal, VA 11/7/1995 558 509 558 540 558 540 558 558 540 527 534 558 6,538 17.902064000 Falling River near Naruna, VA 11/29/1990 713 650 713 690 713 690 713 713 690 682 662 713 8,342 22.802065500 Cub Creek at Phenix, VA 1/28/1999 438 424 465 450 465 450 465 465 450 434 420 434 5,360 14.702066000 Roanoke (Staunton) River at Randolph, VA 8/30/1995 558 509 558 540 558 540 558 560 570 558 540 558 6,607 18.102069700 South Mayo River near Nettleridge, VA 5/8/2001 372 339 372 360 396 390 403 403 390 372 360 372 4,529 12.402070000 North Mayo River near Spencer, VA 12/5/2001 372 339 372 360 372 360 372 372 360 341 330 368 4,318 11.802071530 Smith River at Smith Riv Church near Woolwine, VA 10/7/1997 496 452 496 480 496 480 496 496 480 490 480 496 5,838 16.002072000 Smith River near Philpott, VA 4/28/1998 465 424 465 453 496 480 496 496 480 465 450 465 5,635 15.402072500 Smith River at Bassett, VA 1/3/1996 556 509 558 540 558 540 558 558 540 527 510 527 6,481 17.702073000 Smith River at Martinsville, VA 3/20/2002 341 311 353 360 372 360 372 372 360 341 330 341 4,213 11.502074500 Sandy River near Danville, VA 11/29/1990 713 650 713 690 713 690 713 713 690 682 662 713 8,342 22.802075045 Dan River at Stp near Danville, VA 3/10/1997 496 452 518 510 527 510 527 527 510 496 480 496 6,049 16.602075500 Dan River at Paces, VA 11/6/1995 558 509 558 540 558 540 558 558 540 527 535 558 6,539 17.902077000 Banister River at Halifax, VA 8/22/1991 651 593 657 660 682 645 635 621 636 655 627 648 7,710 21.102077500 Hyco River near Denniston, VA 11/13/1996 527 480 527 510 527 510 527 527 510 496 498 527 6,166 16.902079640 Allen Creek near Boydton, VA 12/5/1990 589 537 589 570 589 570 589 589 570 547 512 585 6,836 18.703164000 New River near Galax, VA 11/18/1994 589 537 589 570 589 570 589 589 570 558 553 589 6,892 18.903165000 Chestnut Creek at Galax, VA 11/22/1996 527 480 527 510 527 510 527 527 510 496 489 527 6,157 16.903165500 New River at Ivanhoe, VA 12/19/1997 496 452 496 480 496 480 496 496 480 465 450 478 5,765 15.803167000 Reed Creek at Grahams Forge, VA 3/21/2001 372 339 383 390 403 390 403 403 390 372 360 372 4,577 12.503168000 New River at Allisonia, VA 11/14/1994 589 537 589 570 589 570 589 589 570 558 557 589 6,896 18.903170000 Little River at Graysontown, VA 11/14/2000 403 367 403 390 403 390 403 403 390 372 377 403 4,704 12.903171000 New River at Radford, VA 12/29/1994 589 537 589 570 589 570 589 589 570 558 540 561 6,851 18.803173000 Walker Creek at Bane, VA 11/16/1994 589 537 589 570 589 570 589 589 570 558 555 589 6,894 18.903175500 Wolf Creek near Narrows, VA 11/16/1994 558 508 558 540 558 540 558 558 540 496 514 558 6,486 17.803176500 New River at Glen Lyn, VA 11/16/1994 589 537 589 570 589 570 589 589 570 558 555 589 6,894 18.903177710 Bluestone River at Falls Mills, VA 10/7/1993 403 367 403 387 372 360 372 372 360 366 360 396 4,518 12.403207800 Levisa Fork at Big Rock, VA 11/14/1994 589 537 589 570 589 570 589 589 570 558 557 589 6,896 18.903208500 Russell Fork at Haysi, VA 11/15/1994 589 537 589 570 589 570 589 589 570 558 556 589 6,895 18.9
Table 21 81

Table 21. Number of days of available Qprev record for streamgages in Virginia, by streamgage and month, and earliest date the records are available, during water years 1991–2013.—Continued[Qprev, the flow value from the shifted rating table in effect at the time of the previous flow measurement that corresponds to the gage height of each day’s daily flow value; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name Earliest date Number of daily observations of Qprev , by month Total daily observations Total, in years Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

03208950 Cranes Nest River near Clintwood, VA 11/20/1990 713 650 713 690 713 690 713 713 690 682 671 713 8,351 22.903209000 Pound River below Flannagan Dam, near Haysi, VA 11/15/1994 589 537 589 570 589 570 589 589 570 558 556 589 6,895 18.903471500 South Fork Holston River at Riverside, near Chilhowie, VA 11/18/1996 527 480 527 510 527 510 527 527 510 496 493 527 6,161 16.903473000 South Fork Holston River near Damascus, VA 11/18/1996 527 480 527 510 527 510 527 527 510 493 493 527 6,158 16.903474000 Middle Fork Holston River at Seven Mile Ford, VA 12/2/1996 527 480 527 510 527 510 527 527 510 496 480 526 6,147 16.803475000 Middle Fork Holston River near Meadowview, VA 11/18/1996 527 480 527 510 527 510 527 527 510 496 493 527 6,161 16.903478400 Beaver Creek at Bristol, VA 11/14/1996 527 480 527 510 527 510 527 527 510 496 497 527 6,165 16.903488000 North Fork Holston River near Saltville, VA 11/1/1996 527 480 527 510 527 510 527 527 510 496 510 527 6,178 16.903490000 North Fork Holston River near Gate City, VA 1/17/2013 15 28 31 30 31 30 31 31 30 257 0.703524000 Clinch River at Cleveland, VA 11/13/1995 558 509 558 540 558 540 558 558 540 527 528 558 6,532 17.903524500 Guest River at Coeburn, VA 7/22/2013 10 31 30 71 0.203527000 Clinch River at Speers Ferry, VA 11/7/2001 372 339 372 360 372 360 372 372 360 341 354 372 4,346 11.903529500 Powell River at Big Stone Gap, VA 11/6/2001 372 339 372 360 372 360 372 372 360 341 355 372 4,347 11.903531500 Powell River near Jonesville, VA 11/29/1995 558 509 558 540 558 540 558 558 540 527 512 558 6,516 17.8
82 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

Table 22. Control and rating stability assessments made by senior hydrographers in the Virginia Water Science Center and Virginia 

Department of Environmental Quality for streamgages in Virginia active September 30, 2013.—Continued

[–, no response; E, excellent; G, good; F, fair; P, poor. Averages were computed by assigning numeric equivalents of 4 for excellent, 3 for good, 2 for fair, and 1 

for poor. Italicized sites were not characterized by any hydrographer in response to questionnaires and were assigned scores by the authors from other descriptions. Individual hydrographers are identified by number, chronologically in the order that questionnaires were received; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name

Hydrographer Number 

of 

replies

Average 

stability 

score

1 2 3 4 5 6 7 8 9 10

01613900 Hogue Creek near Hayfield, VA F – – G – – – – – – 2 2.5

01615000 Opequon Creek near Berryville, VA – – – G – – – G – – 2 3.0

01616100 Dry Marsh Run near Berryville, VA – – E F – – – F – – 3 2.7

01620500 North River near Stokesville, VA – – F G – – – – G – 3 2.7

01621050 Muddy Creek at Mount Clinton, VA – – G G – – – – G – 3 3.0

01622000 North River near Burketown, VA F – – G – – – – – – 2 2.5

01625000 Middle River near Grottoes, VA F – – G – – – – – – 2 2.5

01626000 South River near Waynesboro, VA F – – G – – – – – – 2 2.5

01626850 South River near Dooms, VA F – – G – – – – – – 2 2.5

01627500 South River at Harriston, VA F – – G – – – – – – 2 2.5

01628500 South Fork Shenandoah River near Lynnwood, VA – – G E – – – – – – 2 3.5

01629500 South Fork Shenandoah River near Luray, VA F – – G – – – – – – 2 2.5

01631000 South Fork Shenandoah River at Front Royal, VA – – G G – – – G – – 3 3.0

01632000 North Fork Shenandoah River at Cootes Store, VA – – F G – – – G G – 4 2.8

01632082 Linville Creek at Broadway, VA F – – G – – – – – – 2 2.5

01632900 Smith Creek near New Market, VA – – – F – – – G – – 2 2.5

01633000 North Fork Shenandoah River at Mount Jackson, VA F – – G – – – – – – 2 2.5

01634000 North Fork Shenandoah River near Strasburg, VA – – E G – – – G – – 3 3.3

01634500 Cedar Creek near Winchester, VA G – – G – – – – – – 2 3.0

01635500 Passage Creek near Buckton, VA G – – G – – – – – – 2 3.0

01636316 Spout Run at Rt 621 near Millwood, VA – – E – – – – G – – 2 3.5

01636690 Piney Run near Lovettsville, VA – – G – – – – P – – 2 2.0

01638350 South Fork Catoctin Creek at Rt 698 near Waterford, VA – – G – – – – P – – 2 2.0

01638420 North Fork Catoctin Creek at Rt 681 near Waterford, VA – – G – – – – G – – 2 3.0

01638480 Catoctin Creek at Taylorstown, VA P – – P – – – – – – 2 1.0

01643590 Limestone Branch near Leesburg, VA – – F – – – – G – – 2 2.5

01643700 Goose Creek near Middleburg, VA – – G – – – – F – – 2 2.5

01643805 North Fork Goose Creek at Rt 729 near Lincoln, VA – – P – – – – F – – 2 1.5

01643880 Beaverdam Creek at Rt 734 near Mountville, VA – – F – – – – G – – 2 2.5

01644000 Goose Creek near Leesburg, VA F – – F – – – – – – 2 2.0

01644280 Broad Run near Leesburg, VA – G F – – – – – – – 2 2.5

01645704 Difficult Run above Fox Lake near Fairfax, VA – F P – – G – – – – 3 2.0

01645762 South Fork Little Difficult Run above Mouth near Vienna, VA – F P – – P – – – – 3 1.3

01646000 Difficult Run near Great Falls, VA – G G G – F – – – – 4 2.8

01646305 Dead Run at Whann Avenue near Mclean, VA – F P – – P – – – – 3 1.3

01652500 Fourmile Run at Alexandria, VA – F F – – P – – – – 3 1.7

01653000 Cameron Run at Alexandria, VA – F F – – P – – – – 3 1.7

0165389205 Accotink Creek near Ranger Road at Fairfax, VA – – G – – – – – – – 1 3.0

01654000 Accotink Creek near Annandale, VA – P P P – P – – – – 4 1.0

01656000 Cedar Run near Catlett, VA F – – G – – – – – – 2 2.5

01656903 Flatlick Branch above Frog Branch at Chantilly, VA – F F – – G – – – – 3 2.3

01658500 South Fork Quantico Creek near Independent Hill, VA – – F – – F – – – – 2 2.0

01660400 Aquia Creek near Garrisonville, VA – – F – – G – – G – 3 2.7

01662800 Battle Run near Laurel Mills, VA F – – F – – – – – – 2 2.0

01663500 Hazel River at Rixeyville, VA – – G – – G – – G – 3 3.0
Table 22 83

Table 22. Control and rating stability assessments made by senior hydrographers in the Virginia Water Science Center and Virginia 

Department of Environmental Quality for streamgages in Virginia active September 30, 2013.—Continued

[–, no response; E, excellent; G, good; F, fair; P, poor. Averages were computed by assigning numeric equivalents of 4 for excellent, 3 for good, 2 for fair, and 1 

for poor. Italicized sites were not characterized by any hydrographer in response to questionnaires and were assigned scores by the authors from other descriptions. Individual hydrographers are identified by number, chronologically in the order that questionnaires were received; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name

Hydrographer Number 

of 

replies

Average 

stability 

score

1 2 3 4 5 6 7 8 9 10

01664000 Rappahannock River at Remington, VA – – G – – G – – G – 3 3.0

01665500 Rapidan River near Ruckersville, VA F – – G – – – – – – 2 2.5

01666500 Robinson River near Locust Dale, VA F – – F – – – – – – 2 2.0

01667500 Rapidan River near Culpeper, VA F – – E – – – – – – 2 3.0

01668000 Rappahannock River near Fredericksburg, VA – – F – – G – – G – 3 2.7

01669000 Piscataway Creek near Tappahannock, VA P – – P – – – – – – 2 1.0

01669520 Dragon Swamp at Mascot, VA P – – – – – – – – – 1 1.0

01670400 North Anna River near Partlow, VA – – G – – G G – – – 3 3.0

01671020 North Anna River at Hart Corner near Doswell, VA – – – F – – – – – – 1 2.0

01671025 North Anna River above Little River near Doswell, VA P – F – – F G – F – 5 2.0

01671100 Little River near Doswell, VA F – – F – – – – – – 2 2.0

01672500 South Anna River near Ashland, VA – – G – – G G – G – 4 3.0

01673000 Pamunkey River near Hanover, VA – – G – – G F – G – 4 2.8

01673550 Totopotomoy Creek near Studley, VA P – – P – – – – – – 2 1.0

01673800 Po River near Spotsylvania, VA P – – G – – – – – – 2 2.0

01674000 Mattaponi River near Bowling Green, VA – – G G – G – – G – 4 3.0

01674500 Mattaponi River near Beulahville, VA – – G – – G – – G – 3 3.0

02011400 Jackson River near Bacova, VA – – G E – – – – – – 2 3.5

02011460 Back Creek near Sunrise, VA – – – E – – – – – – 1 4.0

02011470 Back Creek at Sunrise, VA – – – E – – – – – – 1 4.0

02011490 Little Back Creek near Sunrise, VA – – – E – – – – – – 1 4.0

02011500 Back Creek near Mountain Grove, VA – – – E – – – – – – 1 4.0

02011800 Jackson River below Gathright Dam near Hot Spgs, VA – – – E – – – – – – 1 4.0

02013000 Dunlap Creek near Covington, VA – – – G – – – – – – 1 3.0

02013100 Jackson River below Dunlap Creek at Covington, VA – – – G – – – – – – 1 3.0

02014000 Potts Creek near Covington, VA – – – G – – – – – – 1 3.0

02015700 Bullpasture River at Williamsville, VA F – – G – – – – – – 2 2.5

02016000 Cowpasture River near Clifton Forge, VA – G – E – – – – – – 2 3.5

02016500 James River at Lick Run, VA – G – E – – – – – – 2 3.5

02017500 Johns Creek at New Castle, VA F – – G – – – – – – 2 2.5

02018000 Craig Creek at Parr, VA – G – G – – – – – – 2 3.0

02018500 Catawba Creek near Catawba, VA F – – G – – – – – – 2 2.5

02019500 James River at Buchanan, VA – G – E – – – – – – 2 3.5

02020500 Calfpasture River above Mill Creek at Goshen, VA F – – G – – – – – – 2 2.5

02021500 Maury River at Rockbridge Baths, VA – G G E – – – – G – 4 3.3

02022500 Kerrs Creek near Lexington, VA G – – G – – – – – – 2 3.0

02024000 Maury River near Buena Vista, VA – G F G – – – – G – 4 2.8

02024752 James River at Blue Ridge Pkwy near Big Island, VA G – P G – – – – – – 3 2.3

02024915 Pedlar River at Forest Road near Buena Vista, VA F – – G – – – – – – 2 2.5

02025500 James River at Holcomb Rock, VA – F F E – – – – G – 4 2.8

02026000 James River at Bent Creek, VA – F G E – – – – G – 4 3.0

02027000 Tye River near Lovingston, VA F – – G – – – – – – 2 2.5

02027500 Piney River at Piney River, VA F – – G – – – – – – 2 2.5

02028500 Rockfish River near Greenfield, VA F – – G – – – – – – 2 2.5

02029000 James River at Scottsville, VA – – G E – E G – G – 5 3.4
84 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

Table 22. Control and rating stability assessments made by senior hydrographers in the Virginia Water Science Center and Virginia 

Department of Environmental Quality for streamgages in Virginia active September 30, 2013.—Continued

[–, no response; E, excellent; G, good; F, fair; P, poor. Averages were computed by assigning numeric equivalents of 4 for excellent, 3 for good, 2 for fair, and 1 

for poor. Italicized sites were not characterized by any hydrographer in response to questionnaires and were assigned scores by the authors from other descriptions. Individual hydrographers are identified by number, chronologically in the order that questionnaires were received; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name

Hydrographer Number 

of 

replies

Average 

stability 

score

1 2 3 4 5 6 7 8 9 10

02030000 Hardware River below Briery Run near Scottsville, VA P – – G – – – – – – 2 2.0

02030500 Slate River near Arvonia, VA F – – G – – – – – – 2 2.5

02031000 Mechums River near White Hall, VA F – – G – – – – – – 2 2.5

02032250 Moormans River near Free Union, VA F – – G – – – – – – 2 2.5

02032640 North Fork Rivanna River near Earlysville, VA F – – G – – – – – – 2 2.5

02034000 Rivanna River at Palmyra, VA F – – G – – – – – – 2 2.5

02035000 James River at Cartersville, VA – – G – – E G – E – 4 3.5

02036500 Fine Creek at Fine Creek Mills, VA F – – E – – – – – – 2 3.0

02037000 James River And Kanawha Canal near Richmond, VA P – – G – – – – – – 2 2.0

02037500 James River near Richmond, VA G – – E – – – – – – 2 3.5

02038850 Holiday Creek near Andersonville, VA – – F – – – G – G – 3 2.7

02039000 Buffalo Creek near Hampden Sydney, VA F – – F – – – – – – 2 2.0

02039500 Appomattox River at Farmville, VA – – G G – G G – G – 5 3.0

02040000 Appomattox River at Mattoax, VA P – – F – – – – – – 2 1.5

02040892 Appomattox River at Route 602 near Mannboro, VA – – G – – G G – G – 4 3.0

02041000 Deep Creek near Mannboro, VA P – – F – – – – – – 2 1.5

02041650 Appomattox River at Matoaca, VA F – – G – – – – – – 2 2.5

02042500 Chickahominy River near Providence Forge, VA – – E – – G G – G – 4 3.3

02044500 Nottoway River near Rawlings, VA F – – G – – – – – – 2 2.5

02045500 Nottoway River near Stony Creek, VA F – – G – – – – – – 2 2.5

02046000 Stony Creek near Dinwiddie, VA F – – G – – – – – – 2 2.5

02047000 Nottoway River near Sebrell, VA – – F – – G – – G – 3 2.7

02047500 Blackwater River near Dendron, VA P – – – – – – – – – 1 1.0

02049500 Blackwater River near Franklin, VA – – P – – P – – F – 3 1.3

02051000 North Meherrin River near Lunenburg, VA F – – G – – – – – – 2 2.5

02051500 Meherrin River near Lawrenceville, VA – – G – – G – – F – 3 2.7

02052000 Meherrin River at Emporia, VA P – – F – – – – – – 2 1.5

02053800 South Fork Roanoke River near Shawsville, VA F – – G – – – – – – 2 2.5

02054500 Roanoke River at Lafayette, VA F – – G – – – – – – 2 2.5

02054530 Roanoke River at Glenvar, VA F – – G – – – – – – 2 2.5

02055000 Roanoke River at Roanoke, VA – G – G – – – – – – 2 3.0

02055100 Tinker Creek near Daleville, VA – – – G – – – – – – 1 3.0

02056000 Roanoke River at Niagara, VA – G – G – – – – – – 2 3.0

02056650 Back Creek near Dundee, VA F – – G – – – – – – 2 2.5

02056900 Blackwater River near Rocky Mount, VA G – – G – – – – – – 2 3.0

02058400 Pigg River near Sandy Level, VA – – P – – F – – G – 3 2.0

02059485 Goose Creek at Rt 747 near Bunker Hill, VA – – – – – – – – – – 0 3.0

02059500 Goose Creek near Huddleston, VA G – – G – – – – – – 2 3.0

02060500 Roanoke River at Altavista, VA – – G – – G – – G – 3 3.0

02061000 Big Otter River near Bedford, VA – – – – – – – – – – 0 3.0

02061500 Big Otter River near Evington, VA F – – G – – – – – – 2 2.5

02062500 Roanoke (Staunton) River at Brookneal, VA – – G – – G – – G – 3 3.0

02064000 Falling River near Naruna, VA G – – G – – – – – – 2 3.0

02065500 Cub Creek at Phenix, VA F – – F – – – – – – 2 2.0

02066000 Roanoke (Staunton) River at Randolph, VA – – F – – G – – G – 3 2.7
Table 22 85

Table 22. Control and rating stability assessments made by senior hydrographers in the Virginia Water Science Center and Virginia 

Department of Environmental Quality for streamgages in Virginia active September 30, 2013.—Continued

[–, no response; E, excellent; G, good; F, fair; P, poor. Averages were computed by assigning numeric equivalents of 4 for excellent, 3 for good, 2 for fair, and 1 

for poor. Italicized sites were not characterized by any hydrographer in response to questionnaires and were assigned scores by the authors from other descriptions. Individual hydrographers are identified by number, chronologically in the order that questionnaires were received; VA, Virginia; Rt, Route]

Streamgage 

number Streamgage name

Hydrographer Number 

of 

replies

Average 

stability 

score

1 2 3 4 5 6 7 8 9 10

02069700 South Mayo River near Nettleridge, VA F – – F – – – – – – 2 2.0

02070000 North Mayo River near Spencer, VA F – – G – – – – – – 2 2.5

02071530 Smith River at Smith Riv Church near Woolwine, VA F – – F – – – – – – 2 2.0

02072000 Smith River near Philpott, VA – – G – – E – – G – 3 3.3

02072500 Smith River at Bassett, VA – – G – – E – – G – 3 3.3

02073000 Smith River at Martinsville, VA P – – G – – – – – – 2 2.0

02074500 Sandy River near Danville, VA G – – G – – – – – – 2 3.0

02075045 Dan River at Stp near Danville, VA – – G – – G – – G – 3 3.0

02075500 Dan River at Paces, VA – – F – – F – – F – 3 2.0

02077000 Banister River at Halifax, VA – – G – – G – – G – 3 3.0

02077500 Hyco River near Denniston, VA – – P – – – – – G – 2 2.0

02079640 Allen Creek near Boydton, VA F – – F – – – – – – 2 2.0

03164000 New River near Galax, VA – – – – G – – – – G 2 3.0

03165000 Chestnut Creek at Galax, VA – – – – E – – – – E 2 4.0

03165500 New River at Ivanhoe, VA – – – – G – – – – F 2 2.5

03167000 Reed Creek at Grahams Forge, VA – – – – G – – – – G 2 3.0

03168000 New River at Allisonia, VA – – – – E – – – – E 2 4.0

03170000 Little River at Graysontown, VA – – – – G – – – – G 2 3.0

03171000 New River at Radford, VA – – – – G – – – – G 2 3.0

03173000 Walker Creek at Bane, VA – – – – G – – – – G 2 3.0

03175500 Wolf Creek near Narrows, VA – – – – G – – – – G 2 3.0

03176500 New River at Glen Lyn, VA – – – – G – – – – G 2 3.0

03177710 Bluestone River at Falls Mills, VA – – – – F – – – – G 2 2.5

03207800 Levisa Fork at Big Rock, VA – – – – G – – – – G 2 3.0

03208500 Russell Fork at Haysi, VA – – – – G – – – – G 2 3.0

03208950 Cranes Nest River near Clintwood, VA – – – – P – – – – F 2 1.5

03209000 Pound River below Flannagan Dam, near Haysi, VA – – – – G – – – – G 2 3.0

03471500 South Fork Holston River at Riverside, near Chilhowie, VA – – – – G – – – – G 2 3.0

03473000 South Fork Holston River near Damascus, VA – – – – G – – – – G 2 3.0

03474000 Middle Fork Holston River at Seven Mile Ford, VA – – – – E – – – – E 2 4.0

03475000 Middle Fork Holston River near Meadowview, VA – – – – G – – – – G 2 3.0

03478400 Beaver Creek at Bristol, VA – – – – G – – – – G 2 3.0

03488000 North Fork Holston River near Saltville, VA – – – – G – – – – G 2 3.0

03490000 North Fork Holston River near Gate City, VA – – – – F – – – – F 2 2.0

03524000 Clinch River at Cleveland, VA – – – – G – – – – G 2 3.0

03524500 Guest River at Coeburn, VA – – – – F – – – – G 2 2.5

03527000 Clinch River at Speers Ferry, VA – – – – F – – – – G 2 2.5

03529500 Powell River at Big Stone Gap, VA – – – – F – – – – F 2 2.0

03531500 Powell River near Jonesville, VA – – – – G – – – – G 2 3.0

Totals: 174 69 19 61 100 27 36 10 14 35 27 398 2.6

Appendix 1. Plots for real-time streamgages in Virginia 87

Appendix 1. Plots for real-time streamgages in Virginia

A. All available measurements

Three columns of plots for all real-time streamgages in Virginia active on September 30, 2013, with 20 or more flow

measurements with positive flow values, organized by major river basin, with all available measurements for each site color 

coded by rating family showing (1) stage, flow, and a generalized additive model (GAM) curve. Appendix 1A depicts all 

available measurements for each plot, unlike appendix 1B, which groups measurements at each site by rating families. Rating 

families represent a series of measurements made during a period when a streamgage control was at relative equilibrium. For 

streamgages where more than one rating family was identified, they were numbered sequentially in chronological order as RF1, 

RF2, ... RFn; non-sequential rating family numbers result from situations in which a rating family was omitted because its 

period of equilibrium did not last long enough for a sufficient number of measurements to be made to allow a meaningful GAM 

to be developed. The coefficient of determination for the GAM curve, R2, is a measure of the amount of variation in the stagestreamflow relation explained by the GAM; (2) residuals from the GAM curve by date (times series scale of graphs vary), with 

a LOESS smoother; and (3) residuals from the GAM curve by Julian date, with a LOESS smoother. Shaded areas represent the 

99-percent confidence interval of the relevant curve.

B. Measurements grouped by rating families

Three columns of plots for all real-time streamgages in Virginia active on September 30, 2013, with 20 or more flow measurements with positive flow values organized by major river basin, with all available measurements for each site, showing (1) 

stage, flow, and a generalized additive model (GAM) curve. Unlike appendix 1A, which depicts all available measurements for 

each plot, appendix 1B groups measurements at each site by rating families. Rating families represent a series of measurements 

made during a period when a streamgage control was at relative equilibrium. For streamgages where more than one rating family was identified, they were numbered sequentially in chronological order as RF1, RF2, ... RFn; non-sequential rating family 

numbers result from situations in which a rating family was omitted because its period of equilibrium did not last long enough 

for a sufficient number of measurements to be made to allow a meaningful GAM to be developed. The coefficient of determination for the GAM curve, R2

, is a measure of the amount of variation in the stage-streamflow relation explained by the GAM; 

(2) residuals from the GAM curve by date, and (3) residuals from the GAM curve by Julian date. Shaded areas represent the

99-percent confidence interval of the relevant curve.

Appendix 1 is available online at https://doi.org/10.3133/sir20175137
88 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

Appendix 2. Computation of Alternative Flow (AltFlow) Data

Two primary datasets were used to develop the AltFlow 

tables, (1) daily flow values for 1990–2013 and (2) the 

compiled tables of expanded shifted ratings (Messinger and 

Burgholzer, 2017). Two ancillary datasets also were used. A 

table containing all flow measurements was retrieved from 

NWIS-Web (National Water Information System-Web) and 

used to identify dates on which those flow measurements were 

made. Daily flows (Qmeas) were retrieved from NWIS-Web. 

A table of all shifts was retrieved from the NWIS commandline interface and manually processed to identify the earliest 

dates for each streamgage for which shifts were stored in the 

database (table 2).

Columns in the AltFlow table that originated in the 

retrieval of daily flow values included station number 

(site_no), date, flow in cubic feet per second, and qualifier 

(Messinger and Burgholzer, 2017). Because dates in other 

files were formatted in multiple ways, date in the original 

MM/DD/YYYY format (month as a two-digit number, date 

as a two-digit number, and year as a four-digit number, with 

the three sets of numbers separated by slashes) was retained. 

Another column was created and populated with date in the 

YYYYMMDD format (year as a four-digit number, month as 

a two-digit number, and date as a two-digit number, with no 

separators of any type between the three sets of numbers). 

For each streamgage, the earliest date when AltFlows 

could be computed was determined (“Valid Start Date”). This 

date was the earliest date for which both base ratings and 

shifts were available. Both shifts and ratings were assumed 

to be continuously available following this date. These dates 

were identified in a table developed from retrievals of ratings 

and shifts, and imported to this table using the Microsoft Excel 

VLOOKUP command with the site_no used for the lookup 

value. Once analysis and verification related to that table was 

final, the formulas were converted to values in order to reduce 

file size. All dates with values of Qmeas were compared to 

Valid Start Date for the relevant streamgage and flagged as to 

whether or not valid values for Qprev and Qsame could potentially 

be computed for that date. 

The column “Lookup” contains a unique identifier for 

streamgage-date combinations. It is of the format Q.site_

no.yyyymmdd, where site_no is the 8- or 10-digit station 

number and yyyymmdd is the date. The column was populated 

by concatenating the letter “Q” and the two other values; the 

letter “Q” was used as the first character in order to prevent 

Excel, R, and other software from truncating the leading zero 

from the station number. Lookup was used in conjunction with 

the VLOOKUP and INDEX/MATCH commands to populate 

several columns in this table by importing values from other 

tables.

The column “Expanded rating code” contains the value 

from the Lookup column for the dates when a retrieval of 

the expanded shifted rating table was desired. These represent dates when a flow measurement was made. This column 

was developed in order to simplify filtering the table for 

verification checks and to reduce the complexity of IF statements used elsewhere in the table. It was populated by using 

the VLOOKUP command to retrieve the same code from a 

table of flow measurements; for dates not represented in the 

other table, an error code was returned. This table of flow 

measurements was obtained from NWIS-Web, and the only 

manual processing step that needed to be done in order to use 

it to develop the column “Expanded rating code” was to concatenate the letter “Q” with the values for station numbers and 

dates into a new column. To prevent unintended changes to 

this column and to reduce file size, the column was converted 

to values, and the error codes were deleted. 

The column “NewSite” describes whether each row 

represents the first row for a new site when the table is sorted 

by station number then by date. The column was developed 

in order to make the table simpler to filter and troubleshoot. 

This statement is dependent on the sort order of the table and 

requires that the table be sorted first by site_no and then by 

date in chronological order.

The column “Rating lookup code, Qsame” contains the 

lookup code for the appropriate expanded shifted rating to 

compute Qsame. It was populated using an IF statement that 

checks the previous two columns. If the column “Expanded 

rating code” contains a non-blank value, the statement returns 

that value. If the column “NewSite” indicates the site is new, it 

returns the value “No rating available” until the first rating is 

available. Otherwise, the statement copies the previous value 

in this column. Like the statement in the column “NewSite,” 

this statement is dependent on the sort order of the table and 

requires that the table be sorted first by site_no, then chronologically. The statement was written to allow the inclusion of 

values from the period before valid expanded shifted ratings 

were available because of the iterative fashion in which this 

dataset was developed and to accommodate the possibility that 

the initial retrieval was incomplete and additional valid shifts 

might be located. 

The column “Stage” contains a derived value for stage. 

It is the stage value corresponding to the flow value closest 

to Qmeas in the relevant expanded shifted rating. The column 

was populated through a reverse lookup from the rating tables 

using the INDEX, MATCH, and OFFSET commands. The 

value from “Rating lookup code, Qsame” was used to find the 

appropriate column in the table of ratings; then the stage value 

matching the closest discharge value to Qmeas from that column 

was returned. Although all possible values of stage appear 

in rating tables, not all possible values of flow appear. Daily 

mean flow is computed by averaging the unit values for flow 

observed on a particular day, so the value of Qmeas may be a 

number that does not appear on a rating table. If flow values 

and ratings are added to those in the files, the addresses in the 

INDEX-MATCH-OFFSET statement must be modified to 

accommodate them.

This issue of rounding and of rating tables lacking many 

possible values for Qmeas was the reason the column “Qsame” 
Appendix 2. Computation of Alternative Flow (AltFlow) Data 89

was developed. The column “Qsame” gives the flow value 

corresponding to the Stage value in the relevant rating table. 

This was done to remove one source of error when comparing the changes in rating tables in effect from the time of one 

flow measurement to the next. A direct comparison between 

Qmeas and Qprev often included differences in flow for the same 

value of Stage, even if the rating was unchanged. The column 

was populated through a lookup from the rating tables using 

the INDEX and MATCH commands. The value from “Rating 

lookup code, Qsame” was used to find the appropriate column 

in the table of ratings, then the flow value from that column 

on the row matching the value for Stage was returned. If flow 

values and ratings are added to those in the files, the addresses 

in the INDEX-MATCH-OFFSET statement must be modified 

to accommodate them.

The column “Rating lookup code, Qprev” contains the 

lookup code for the appropriate expanded shifted rating to 

compute Qprev, the flow value that would have been obtained 

had the expanded shifted rating in effect at the time of the previous flow measurement remained in effect. It was populated 

using an IF statement that checks “Expanded rating code” and 

“Rating Lookup Code, Qsame.” If the column “Rating Lookup 

Code, Qsame” contains the value “No rating available,” the 

statement returns that value. For values in that column that are 

not equal to values in the previous cell in that same column, it 

returns the value from that previous cell. Otherwise, the statement copies the value in this previous cell of its own column. 

Like the statements in the columns “NewSite” and “Rating 

Lookup Code, Qsame,” this statement is dependent on the sort 

order of the table and requires that the table be sorted first by 

site_no, then chronologically. 

The column “DifferenceQsame” gives the difference 

between Qmeas and Qsame. It was obtained by subtracting Qsame

from Qmeas. This column was developed for troubleshooting.

The column “Qprev” gives the flow value that would have 

been obtained from the expanded shifted rating in effect at the 

time of the previous flow measurement, had it remained in 

effect. The column was populated through a lookup from the 

rating tables using the INDEX and MATCH commands. The 

value from “Rating lookup code, Qprev” was used to find the 

appropriate column in the table of ratings, then the flow value 

from that column on the row matching the value for Stage 

was returned. Valid values for Qprev became available once two 

flow measurements were made after the base ratings and shifts 

began to be stored in the database. For the period between the 

first and second flow measurements subsequent to shifts being 

stored in the database, values of Qsame are available, but values 

of Qprev are not. If flow values and ratings are added to those in 

the files, the addresses in the INDEX-MATCH-OFFSET statement must be modified to accommodate them.

The column “DifferenceQprev” gives the difference 

between Qmeas and Qprev. It was obtained by subtracting Qprev

from Qmeas. This column was developed for troubleshooting.

The column “Check for hiatus” checks for a hiatus in 

record. It was populated using an IF statement that, within the 

records for a given streamgage, checks whether successive 

values in the “Date” column are more than one day in magnitude; when they are, the row in question is flagged as representing a hiatus in record. For such records, the ratings in 

effect before the hiatus were judged to be unrepresentative 

of variation typical from one normally scheduled site visit 

to the next, and values of Qprev were deleted for the period 

before two post-hiatus site visits had been made. One site, 

01671025, North Anna River above Little River near Doswell, 

is a continuous station with a limited discharge computation 

range, and as a result, it had numerous breaks in record of one 

to several days that resulted in false positives for this IF statement. The column “Comments” contains comments, principally relating to a hiatus in record or other reason for values to 

have been deleted.

If a user of this spreadsheet wishes to update the AltFlow 

record as new data become available, that may be accomplished by using the following procedure.

1. Open the desired file and determine whether available 

computers will process the files in an acceptable manner. 

If not, consider editing historical ratings and daily values 

out of the files to speed processing times.

2. Retrieve the desired daily values from NWIS-Web and 

paste them to the bottom of the table that contains daily 

values from the same streamgages. Sort each table so that 

data are grouped first by site, and then chronologically.

3. Retrieve a table of flow measurements for the same period 

from NWIS-Web. Extract the station numbers and dates 

for each site visit.

4. Follow the procedure described above to obtain and format all the necessary expanded, shifted ratings. Append 

the additional ratings to the tables which contain ratings 

from the same streamgages. 

5. Modify the INDEX-MATCH and INDEX-MATCH-OFFSET commands in the flow tables so that they include the 

entire updated range of values in the rating tables.

6. Copy the formulas in the flow tables to the blank cells in 

the rows that have been added. Compute the AltFlows. 

7. If desired, copy the AltFlows as values to a separate, 

smaller file for further analysis.

References Cited

Messinger, Terence, and Burgholzer, R.W., 2017, Ratings 

and estimated provisional streamflow for streamgages in 

Virginia, water years 1991 through 2013: U.S. Geological 

Survey data release, https://doi.org/10.5066/F72R3PXB.
90 Rating Stability, and Frequency and Magnitude of Shifts, for Streamgages in Virginia through 2013

Appendix 3. UNIX shell scripts used to develop AltFlow record

This software has been approved for release by the U.S. Geological Survey (USGS). Although the software has been 

subjected to rigorous review, the USGS reserves the right to update the software as needed pursuant to further analysis 

and review. No warranty, expressed or implied, is made by the USGS or the U.S. Government as to the functionality of 

the software and related material nor shall the fact of release constitute any such warranty. Furthermore, the software 

is released on condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting 

from its authorized or unauthorized use.

Appendix 3 is a spreadsheet with multiple tabs/worksheets, which contain short UNIX scripts, or Excel formulas that may 

be used to produce one-line UNIX scripts, to perform some of the data manipulation involved in converting expanded, shifted 

ratings retrieved from the National Water Information System as separate files to a joined table of the type in appendix 2, with 

gage height in the left column and one column for each expanded, shifted rating. They have been tested in the ksh shell under 

Solaris Unix version SunOS 5.10. Although these scripts may work on computers running other shells or under other UNIX and 

UNIX-like operating systems, they have not been tested in other environments.

Appendix 3 is available online at https://doi.org/10.3133/sir20175137
Appendix 4. Plots showing daily time series of Qsame and Qprev 91

Appendix 4. Plots showing daily time series of Q

same

 and Q

prev

A. For the North Atlantic Slope Basins

Plots showing daily time series of Qsame (the flow value from the shifted rating table used to compute the daily flow value

at the time of the most recent flow measurement that corresponds to the gage height of each day’s daily flow value) and Qprev

(the flow value from the shifted rating table in effect at the time of the previous flow measurement that corresponds to the gage 

height of each day’s daily flow value) and dates when flow measurements were made for all real-time streamgages in Virginia 

active on September 30, 2013, with 20 or more flow measurements with positive flow values, for the North Atlantic Slope 

Basins. Flows are shown as log10 of the actual flows, and negative values reflect daily flows that were less than 1 cubic foot per 

second. Erratic and abrupt changes in Qprev result from relatively large, sudden changes in ratings.

B. For the South Atlantic Slope Basins

Plots showing daily time series of Qsame (the flow value from the shifted rating table used to compute the daily flow value

at the time of the most recent flow measurement that corresponds to the gage height of each day’s daily flow value) and Qprev

(the flow value from the shifted rating table in effect at the time of the previous flow measurement that corresponds to the gage 

height of each day’s daily flow value) and dates when flow measurements were made for all real-time streamgages in Virginia 

active on September 30, 2013, with 20 or more flow measurements with positive flow values, for the South Atlantic Slope 

Basins. Flows are shown as log10 of the actual flows, and negative values reflect daily flows that were less than 1 cubic foot per 

second. Erratic and abrupt changes in Qprev result from relatively large, sudden changes in ratings.

C. For the Ohio River Basin

Plots showing daily time series of Qsame (the flow value from the shifted rating table used to compute the daily flow value

at the time of the most recent flow measurement that corresponds to the gage height of each day’s daily flow value) and Qprev

(the flow value from the shifted rating table in effect at the time of the previous flow measurement that corresponds to the gage 

height of each day’s daily flow value) and dates when flow measurements were made for all real-time streamgages in Virginia 

active on September 30, 2013, with 20 or more flow measurements with positive flow values, for the Ohio River Basin. Flows 

are shown as log10 of the streamflow in cubic feet per second, and negative values result from daily flows that were less than 

1 cubic foot per second. Erratic and abrupt changes in Qprev reflect relatively large, sudden changes in ratings.

Appendix 4 is available online at https://doi.org/10.3133/sir20175137

For more information concerning the research in this report, contact:

Director, Virginia Water Science Center

U.S. Geological Survey

1730 East Parham Road

Richmond, Virginia 23228

http://va.water.usgs.gov/

Publishing support provided by the 

West Trenton Publishing Service Center 
Messinger and Burgholzer—Rating Stability, and Freqquency and Magnitude of Shifts, for Streamgages in Virginia Through Water Year 2013—Scientific Investigations Report 2017–5137

ISSN 2328-0328 (online)

https://doi.org/10.3133/sir20175137