U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 03–4147

Low-Flow Characteristics and Profiles for the 

Rocky River in the Yadkin-Pee Dee River Basin, 

North Carolina, through 2002

By J. Curtis Weaver and Jason M. Fine

Raleigh, North Carolina

2003

Prepared in cooperation with the 

Water and Sewer Authority of Cabarrus County,

Charlotte-Mecklenburg Utilities, and

Union County
U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

CHARLES G. GROAT, Director

For additional information write to: Copies of this report can be purchased from:

District Chief U.S. Geological Survey

U.S. Geological Survey Branch of Information Services

3916 Sunset Ridge Road Box 25286, Federal Center

Raleigh, NC 27607 Denver, CO 80225

email: dc_nc@usgs.gov 1-888-ASK-USGS (275-8747)

Information about U.S. Geological Survey programs in North Carolina can be obtained on the World Wide Web at 

http://nc.water.usgs.gov.

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

does not constitute endorsement by the U.S. Government.
Contents III

CONTENTS

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

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

Purpose and scope ....................................................................................................................................................... 3

Previous low-flow studies ........................................................................................................................................... 4

Acknowledgments....................................................................................................................................................... 5

Description of the Rocky River basin ................................................................................................................................... 5

Drainage system .......................................................................................................................................................... 6

Major rivers and tributaries ............................................................................................................................... 6

Major flow modifications.................................................................................................................................. 6

Impoundments......................................................................................................................................... 6

Diversions................................................................................................................................................ 9

Climate ........................................................................................................................................................................ 12

Geology and soils........................................................................................................................................................ 12

Land Use ..................................................................................................................................................................... 14

Low-flow characteristics in the Rocky River basin............................................................................................................... 16

Continuous-record stations.......................................................................................................................................... 16

Partial-record sites....................................................................................................................................................... 20

Occurrence of zero or minimal 7Q10 discharges........................................................................................................ 26

Low-flow discharge profiles for the Rocky River................................................................................................................. 27

Summary ............................................................................................................................................................................... 36

Selected references................................................................................................................................................................ 38

Glossary............................................................................................................................................................Inside front cover

PLATES

1. Map showing continuous-record gaging stations and partial-record measuring sites, profiled reach 

of the Rocky River, and generalized area of zero or minimal 7Q10 discharges in the Rocky River basin, 

North Carolina ................................................................................................................................................... In pocket

FIGURES

1–3. Maps showing:

1. Locations of major river basins, the Rocky River basin, and physiographic provinces 

in North Carolina ........................................................................................................................................... 2

2. Hydrologic areas of similar potential to sustain low flows in North Carolina................................................. 6

3. Hydrogeologic units in the Rocky River basin, North Carolina ...................................................................... 15

4–10. Graphs showing:

4. Low-flow frequency curve of annual minimum 7-day average discharges using log-Pearson 

Type III frequency distribution at Rocky River near Norwood, North Carolina (site 169) ........................... 18

5. Correlation of concurrent discharge at the partial-record site at Clarke Creek near 

Harrisburg (site 12) and at the index station at Long Creek near Paw Creek (Catawba River basin) ........... 24

6. Relation of river miles to drainage area for the Rocky River in North Carolina ............................................. 28

7. Relation of river miles to annual 7-day, 10-year (7Q10) low-flow discharge for the Rocky River 

in North Carolina ........................................................................................................................................... 29

8. Relation of river miles to annual 30-day, 2-year (30Q2) low-flow discharge for the Rocky River 

in North Carolina ........................................................................................................................................... 30

9. Relation of river miles to winter 7-day, 10-year (W7Q10) low-flow discharge for the Rocky River 

in North Carolina ........................................................................................................................................... 31

10. Relation of river miles to annual 7-day, 2-year (7Q2) low-flow discharge for the Rocky River 

in North Carolina ........................................................................................................................................... 32

11. Relation of river miles to synoptic discharge measurements made on November 7–8, 2001, 

at selected sites on the Rocky River, North Carolina ............................................................................................ 33
Contents IV

TABLES

1. Summary of selected impoundments and minimum-flow releases in the Rocky River basin 

in North Carolina................................................................................................................................................... 8

2. Summary of selected surface-water withdrawals and return point-source discharges to streams in

the Rocky River basin, North Carolina, 2001 ....................................................................................................... 10

3. Land use in the Rocky River basin in North Carolina ............................................................................................. 14

4. Summary of continuous-record gaging stations and partial-record sites in the Rocky River basin in 

North Carolina where records of gage height and streamflow were collected ..................................................... 41

5. Magnitude and frequency of annual low-flow characteristics at selected continuous-record gaging 1

stations in the Rocky River basin in North Carolina............................................................................................. 17

6. Magnitude and frequency of annual low-flow characteristics at selected partial-record measuring 

sites in the Rocky River basin in North Carolina.................................................................................................. 21

7. Low-flow characteristics for selected partial-record measuring sites and regional equations 

in hydrologic area 9 (HA9) in the Rocky River basin in North Carolina ............................................................. 25

8. Summary of synoptic discharge measurements obtained at selected sites in the Rocky River 

basin in North Carolina, November 7–8, 2001..................................................................................................... 34
Contents V

CONVERSION FACTORS, TEMPERATURE, DATUMS, AND ACRONYMS

Temperature: In this report, temperature is given in degrees Fahrenheit (°F), which can be converted to degrees 

Celsius (°C) by using the following equation:

°C = 5 / 9 (°F – 32)

Vertical coordinates: Vertical coordinates in this report are referenced to the North American Vertical Datum of 

1988 (NAVD 88).

Horizontal coordinates: Unless otherwise specified, horizontal (latitude and longitude) coordinates in this report 

are referenced to the North American Datum of 1927 (NAD 27).

Acronyms:

7Q2 7-day, 2-year low-flow discharge

7Q10 7-day, 10-year low-flow discharge

W7Q10 winter 7-day, 10-year low-flow discharge

30Q2 30-day, 2-year low-flow discharge

DWQ North Carolina Division of Water Quality

GIS geographic information system

HA hydrologic area

MOVE.1 Maintenance of Variance Extension

NAD 27 North American Datum of 1927

NAVD 88 North American Vertical Datum of 1988

NOAA National Oceanic and Atmospheric Administration

NPDES National Pollutant Discharge Elimination System

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey

WTP water-treatment plant

WWTP wastewater-treatment plant

Multiply By To obtain

Length

inch (in.) 25.4 millimeter

foot (ft) 0.3048 meter

mile (mi) 1.609 kilometer

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

Area

acre 4,047 square meter

acre 0.4047 hectare

square mile (mi2) 2.590 square kilometer

Flow

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

million gallons per day (Mgal/d) 0.04381 cubic meter per second

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

cubic foot per second per square mile

[(ft3

/s)/mi2] 0.01093 cubic meter per second per square kilometer

Volume per time

inch per year (in/yr) 2.54 centimeters per year
Abstract 1

Low-Flow Characteristics and Profiles for the 

Rocky River in the Yadkin-Pee Dee River Basin, 

North Carolina, through 2002

By J. Curtis Weaver and Jason M. Fine

ABSTRACT

An understanding of the magnitude and 

frequency of low-flow discharges is an important part 

of protecting surface-water resources and planning for 

municipal and industrial economic expansion. Lowflow characteristics are summarized for 12 continuousrecord gaging stations and 44 partial-record measuring 

sites in the Rocky River basin in North Carolina. 

Records of discharge collected through the 2002 water 

year at continuous-record gaging stations and through 

the 2001 water year at partial-record measuring sites 

were used. Flow characteristics included in the 

summary are (1) average annual unit flow; (2) 7Q10 

low-flow discharge, the minimum average discharge 

for a 7-consecutive-day period occurring, on average, 

once in 10 years; (3) 30Q2 low-flow discharge; 

(4) W7Q10 low-flow discharge, which is similar to 

7Q10 discharge but is based only on flow during the 

winter months of November through March; and 

(5) 7Q2 low-flow discharge.

The Rocky River basin drains 1,413 square miles 

(mi2

) of the southern Piedmont Province in North 

Carolina. The Rocky River is about 91 miles long and 

merges with the Yadkin River in eastern Stanly County 

to form the Pee Dee River, which discharges into the 

Atlantic Ocean in South Carolina. Low-flow 

characteristics compiled for selected sites in the Rocky 

River basin indicated that the potential for sustained 

base flows in the upper half of the basin is relatively 

higher than for streams in the lower half of the basin. 

The upper half of the basin is underlain by the Charlotte 

Belt, where streams have been identified as having 

moderate potentials for sustained base flows. In the 

lower half of the basin, many streams were noted as 

having little to no potential for sustained base flows. 

Much of the decrease in base-flow potential is 

attributed to the underlying rock types of the Carolina 

Slate Belt. Of the 19 sites in the basin having minimal 

(defined as less than 0.05 cubic foot per second) or zero 

7Q10 discharges, 18 sites are located in the lower half 

of the basin underlain by the Carolina Slate Belt. 

Assessment of these 18 sites indicates that streams that 

have drainage areas less than about 25 square miles are 

likely to have minimal or zero 7Q10 discharges. No 

drainage-area threshold for minimal or zero 7Q10 

discharges was identified for the upper half of the 

basin, which is underlain by the Charlotte Belt.

Tributaries to the Rocky River include the 

West Branch Rocky River (22.8 mi2), Clarke Creek 

(28.2 mi2

), Mallard Creek (41.2 mi2), Coddle Creek 

(78.8 mi2

), Reedy Creek (43.0 mi2), Irish Buffalo/

Coldwater Creeks (110 mi2), Dutch Buffalo Creek 

(99 mi2), Long Creek (200 mi2

), Richardson Creek 

(234 mi2

), and Lanes Creek (135 mi2). In the 20-mile 

reach upstream from the mouth (about 22 percent of the 

river length), the drainage area increases by 648 mi2

, or 

about 46 percent of the total drainage area as a result of 

the confluences with Long Creek, Richardson Creek, 

and Lanes Creek.

Low-flow discharge profiles for the Rocky River 

include 7Q10, 30Q2, W7Q10, and 7Q2 discharges in a 

continuous profile with contributions from major 

tributaries included. At the gaging stations above Irish 

Buffalo Creek and near Stanfield, the 7Q10 discharges 

are 25.2 and 42.3 cubic feet per second, corresponding 

to 0.09 and 0.07 cubic feet per second per square mile, 

respectively. At the gaging station near Norwood, the 

7Q10 discharge is 45.8 cubic feet per second, 

equivalent to 0.03 cubic foot per second per square 
2 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002

Figure 1. Locations of major river basins, the Rocky River basin (shown in white), and physiographic provinces in North Carolina.

mile. Low-flow discharge profiles reflect the presence 

of several major flow diversions in the reaches 

upstream from Stanfield and an apparent losing reach 

between the continuous-record gaging stations near 

Stanfield and Norwood, North Carolina.

INTRODUCTION

The need for a better understanding of low-flow 

hydrology and for improved techniques in determining 

low-flow characteristics of streams has become more 

critical as demands for sustained, high-quality water 

supplies and effective waste assimilation have 

increased. The simultaneous occurrence of increasing 

water demands and recent droughts in North Carolina 

have heightened the importance of determining lowflow characteristics.

Low flow, also referred to as base flow or 

sustained fair-weather flow, is composed largely of 

ground-water discharge from aquifers to streams. 

Ground-water discharges have large spatial and 

temporal variations that are highly dependent on 

topographic, geologic, and climatic conditions. The 

high variability of such conditions across North 

Carolina, and sometimes even within a drainage 

basin or along the same stream, results in complex lowflow hydrology. Moreover, the characterization of 

low-flow hydrology is further complicated by 

withdrawals, point-source discharges, impoundments, 

and land use within the drainage basin. Low flows in 

North Carolina typically occur at the conclusion of the 

growing season in late summer and early autumn as a 

result of evaporation from surface-water bodies and use 

of ground water (by way of soil moisture) by crops and 

other vegetation. In addition, the higher temperatures 

of summer and early autumn encourage increased 

water use, which causes a higher demand for 

withdrawals from streams, reservoirs, and groundwater wells. An understanding of low-flow 

characteristics is crucial in evaluating water-supply 

potential and reservoir-release requirements, 

determining and regulating wastewater discharges to 

streams, and maintaining aquatic habitats in streams.

In 1991, the Division of Water Quality (DWQ, 

formerly the Division of Environmental Management) 

of the North Carolina Department of Environment and 

Natural Resources, began using a basinwide approach 

in assessing and managing water quality and, in 

particular, in permitting point-source discharges. This 

approach has been applied to each of the 17 major river 

basins in the State (fig. 1) so that all point-source 

discharges in a basin are permitted simultaneously. The 

process is repeated in each basin at 5-year intervals. In 

conjunction with the basinwide approach, the U.S. 

Geological Survey (USGS), in cooperation with the 

DWQ, has conducted studies to define low-flow 

characteristics and develop discharge profiles for 

selected streams in several river basins (Weaver, 1996, 

1997, 1998; Weaver and Pope, 2001). This basinwide 

investigation of the low-flow characteristics in the 

Rocky River basin was conducted in cooperation with 
Introduction 3

the Water and Sewer Authority of Cabarrus County, 

Charlotte-Mecklenburg Utilities, and Union County.

Where sufficient discharge records are available 

at continuous- and partial-record sites, application of 

statistical techniques, such as those described by Riggs 

(1972), form the basis for determining low-flow 

characteristics. The number of sites with sufficient 

record to determine low-flow characteristics, however, 

is far outnumbered by locations with little or no record 

for developing low-flow estimates.

Low-flow characteristics are defined by a set of 

discharges that are statistically derived values having 

associated duration (expressed as days) and recurrence 

intervals (also referred to as return period and 

expressed in years). The recurrence interval represents 

the average period of time between occurrences of a 

specified low-flow or high-flow hydrologic event 

(see definition in Glossary for more information). An 

example of a widely used low-flow statistic is the 

7-day, 10-year low-flow discharge (hereafter referred 

to as 7Q10 discharge). The annual minimum average 

streamflow for a 7-consecutive-day period will be at or 

below the 7Q10 discharge, on average, one time in 

10 years. If the 7Q10 discharge is 5 cubic feet per 

second (ft3

/s), then the annual minimum average 

streamflow for a 7-consecutive-day period would be 

5 ft3

/s or lower, on average, 1 time in 10 years, 5 times 

in 50 years, or 10 times in 100 years. A recurrence 

interval of 10 years implies that the annual minimum 

average streamflow for a 7-consecutive-day period will 

exceed the 7Q10 discharge, on average, in 9 of 10 

years. Stated another way, the probability is 10 percent 

(the inverse of the recurrence interval) that the lowest 

average 7-consecutive-day flow in any given year will 

be less than the 7Q10 discharge (Giese and Mason, 

1993).

In North Carolina, other low-flow statistics used 

by State regulatory agencies in determining permitting 

limits for withdrawals from and discharges to streams 

include the 30-day, 2-year (30Q2) low-flow discharge; 

winter 7-day, 10-year (W7Q10) low-flow discharge; 

and 7-day, 2-year (7Q2) low-flow discharge. The 

W7Q10 discharge, or winter 7Q10, is defined in a 

similar manner as the 7Q10 discharge except that only 

flows during the months of November through March 

are considered in the analysis.

In addition to providing information to the DWQ 

and other agencies and interested organizations on lowflow characteristics for streams in the Rocky River 

basin and other river basins, the determination of lowflow characteristics provides an expanded knowledge 

of low-flow hydrology and the factors that affect low 

flows in one region as compared to another. As many 

factors become better understood through improved 

and detailed mapping applications, a potential future 

product of this expanded knowledge is the development 

of statistical relations using explanatory variables 

obtained from map products to estimate low-flow 

discharges at ungaged sites.

Purpose and Scope

This report presents low-flow characteristics for 

selected streams in the Rocky River basin of North 

Carolina. Low-flow statistics at streamgaging stations 

are summarized, and drainage-area and low-flow 

discharge profiles for the Rocky River are presented. 

The discharge profiles show the relation of 7Q10, 

30Q2, W7Q10, and 7Q2 discharges to river miles for 

the Rocky River. Descriptions of selected basin 

characteristics include impoundments, flow diversions 

(water-supply withdrawals and return point-source 

discharges), climate, geology, soils, and land use. The 

report also contains an inventory of sites in the study 

area where records of discharge and(or) stage have 

been collected through the 2002 water year for 

continuous-record gaging stations and as of the 2001 

water year for partial-record measuring sites; selected 

site attributes also are listed for each site.

Low-flow statistics are summarized for 

12 continuous-record gaging stations and for 

44 partial-record measuring sites including the average 

annual unit flow and the 7Q10, 30Q2, W7Q10, and 

7Q2 discharges. The number of zero-flow days for 

continuous-record sites and zero-flow discharge 

measurements for partial-record sites also are included. 

Although the period of record varies from site to site, 

records of discharge collected through the 2002 water 

year for continuous-record gaging stations and through 

the 2001 water year for partial-record measuring sites 

were used in the analyses for this report. The records 

of discharge available through the 2002 water year 

for continuous-record sites were included in the 

analyses to account for low flows recorded during the 

1998–2002 drought that affected streams in the Rocky 

River basin and other river basins in North Carolina.

Although low-flow characteristics are presented 

for many sites in the Rocky River basin, no techniques 

similar to those presented by Giese and Mason (1993) 
4 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002

are presented here for estimating low-flow discharges 

at ungaged locations in the study area. Information 

presented in this report is not intended to supersede the 

use of regional relations (Giese and Mason, 1993), 

particularly in the upper parts of the basin where such 

relations are available, but is intended to add to the 

overall means of estimating low-flow discharges in the 

Rocky River basin. Low-flow discharges at ungaged 

locations can also be estimated by examining the unit 

low flows at nearby gaged sites for which low-flow 

characteristics are presented in this report. To the extent 

possible, nearby sites were selected for use as index 

sites based on similarities in basin characteristics of the 

ungaged and index sites. For the upper parts of the 

basin, comparing low-flow discharges estimated by 

using nearby unit low flows to those estimated by using 

regional relations (Giese and Mason, 1993) can provide 

a basis for better understanding the range in values that 

may be applicable to an ungaged site.

Previous Low-Flow Studies

Prior to World War II, low-flow characteristics of 

North Carolina streams were determined only for 

continuous-record gaging stations. Following World 

War II and the subsequent economic expansion, there 

was an increasing need for hydrologic information at 

sites where no data previously had been collected 

(Yonts, 1971). Thus, the USGS expanded its datacollection program in the late 1940’s to include partialrecord measuring sites where discharge measurements 

were made on a periodic basis. Discharge 

measurements made under base-flow conditions along 

with observations of zero flow became the foundation 

of data used in the initial assessments of low-flow 

characteristics of streams in North Carolina. With data 

available from the network of partial-record measuring 

sites, the USGS began to respond to requests for lowflow characteristics on a site-specific basis, including 

those for ungaged sites.

Several studies have been conducted to 

investigate low flows for streams in North Carolina. 

Goddard (1963) presented low-flow characteristics for 

many continuous-record gaging stations in North 

Carolina, along with drainage area and 7Q10 discharge 

profiles developed for selected main-stem rivers. Yonts 

(1971) reported base-flow measurements made at over 

2,200 continuous-record gaging stations and partialrecord measuring sites throughout the State.

Giese and Mason (1993) evaluated low-flow 

characteristics at 122 continuous-record gaging 

stations and 396 partial-record measuring sites with 

drainage areas ranging from 1 to 400 mi2 and 

streamflows unaffected by regulation or diversions. 

Sites were characterized on the basis of similarity in 

their ranges of low-flow discharges and potential to 

sustain base flow. Ten hydrologic areas (HA’s) were 

delineated, and regression equations, which related 

low-flow characteristics to basin characteristics, were 

derived for ungaged sites. Equations for only 4 of the 

10 hydrologic areas—HA10, representing the 

mountains and western Piedmont; HA3, the Sand Hills; 

and HA’s 5 and 9, the eastern and central Piedmont, 

respectively—had standard errors that were considered 

small enough to permit use of the equations in 

estimating low-flow characteristics at the ungaged 

sites.

Evett (1994) investigated the effects of 

urbanization and land-use changes on low flows. 

Trends of decreasing low flows with increasing 

urbanization were detected in data from selected 

continuous-record gaging stations in the Asheville, 

Charlotte, Greensboro, and Raleigh metropolitan areas 

(fig. 1) and at gaging stations in nearby rural areas. 

Because of the decreasing trends noted at both urban 

and rural gaging stations used in the analyses, Evett 

described the results as being statistically inconclusive.

Weaver (1996) conducted a study of low-flow 

characteristics in the Roanoke River basin as part of the 

DWQ’s program of basinwide assessment and 

management of water quality in major river basins of 

North Carolina. Low-flow characteristics were 

summarized for 82 streamflow sites—79 sites in North 

Carolina and 3 sites in Virginia—and profiles of 

drainage area and low-flow discharge were developed 

for 10 selected streams. Total drainage areas for the 

profiled streams range from 22 mi2

 to about 9,700 mi2. 

Low-flow discharges for each stream include 7Q10, 

30Q2, W7Q10, and 7Q2 discharges in a continuous 

profile, and contributions from major tributaries also 

were included.

Weaver (1997) also investigated low-flow 

characteristics in the Deep River basin in the central 

Piedmont Province of North Carolina. The Deep River 

is tributary to the Cape Fear River and drains slightly 

over 1,440 mi2

 in parts of Guilford, Randolph, Moore, 

and Chatham Counties. Low-flow characteristics were 

summarized for 7 continuous-record gaging stations 

and 23 partial-record measuring sites. Drainage-area 
Description of the Rocky River Basin 5

and low-flow discharge profiles were developed for the 

Deep River and were presented in a similar manner as 

those for the Roanoke River basin (Weaver, 1996).

Continuing the series of basinwide low-flow 

investigations, Weaver (1998) summarized low-flow 

characteristics for 50 continuous-record gaging 

stations and 113 partial-record measuring sites in the 

Neuse River basin. Drainage-area and low-flow 

discharge profiles were developed for 10 selected 

streams in the basin. Total drainage areas for the 

profiled streams range from 9 to about 5,600 mi2

. The 

low-flow discharges for each stream include 7Q10, 

30Q2, W7Q10, and 7Q2 discharges in a continuous 

profile with contributions from major tributaries.

Weaver and Pope (2001) also compiled low-flow 

characteristics for 67 continuous-record gaging 

stations and 121 partial-record measuring sites in the 

Cape Fear River basin. Drainage-area and low-flow 

discharge profiles were developed for 13 selected 

streams in the basin. Total drainage areas for the 

profiled streams range from about 44 to almost 

9,100 mi2. As with the previous basins, low-flow 

discharges for each stream include 7Q10, 30Q2, 

W7Q10, and 7Q2 discharges in a continuous profile 

with contributions from major tributaries. Because the 

Deep River is part of the Cape Fear River basin, the 

summary of low-flow characteristics at continuousrecord gaging stations and partial-record measuring 

sites in the Deep River basin (Weaver, 1997) was republished in the Cape Fear River report (Weaver and 

Pope, 2001). However, the drainage-area and low-flow 

discharge profiles developed for the Deep River and 

associated discussions of low-flow characteristics were 

not re-published in the Cape Fear River report.

The methods used by Weaver (1996, 1997, 1998) 

and Weaver and Pope (2001) in previous low-flow 

investigations are the same methods used in this study. 

The presentation of results is similar to the presentation 

of results for the Roanoke, Deep, Neuse, and Cape Fear 

River basins.

Acknowledgments

The authors acknowledge the staffs of the Water 

and Sewer Authority of Cabarrus County, CharlotteMecklenburg Utilities, the Town of Mooresville, and 

the North Carolina Divisions of Water Quality and 

Water Resources for their assistance in compiling 

information about point-source discharge permits, 

water withdrawals, and impoundments. Additional 

information provided by many superintendents and 

operators at local water-treatment plants, including 

local and industrial wastewater-treatment facilities in 

the Rocky River basin, was helpful in the assessment of 

flow modifications on low-flow characteristics.

Finally, the authors gratefully acknowledge the 

contributions of Ms. Cara Hamilton, formerly with the 

U.S. Geological Survey, to this investigation of lowflow characteristics in the Rocky River basin. 

Ms. Hamilton’s research and descriptions of the 

geology and soils in the basin are the basis for much of 

the discussion on these topics.

DESCRIPTION OF THE ROCKY RIVER BASIN

The Rocky River basin drains 1,413 mi2 of the 

southern Piedmont Province in North Carolina (fig. 1), 

and the Rocky River merges with the Yadkin River in 

eastern Stanly County to form the Pee Dee River, 

which discharges into the Atlantic Ocean in South 

Carolina. The Rocky River basin occupies about 21 

percent of the Yadkin-Pee Dee River basin and lies 

within parts of seven counties—Iredell, Rowan, 

Mecklenburg, Cabarrus, Stanly, Union, and Anson 

(pl. 1). The Rocky River basin is characterized by 

rolling and hilly topography. Average ground 

elevations in the basin range from about 180 feet (ft) at 

the mouth of the Rocky River to about 920 ft in the 

northernmost areas of the basin in southeastern Iredell 

and southwestern Rowan Counties.

The Rocky River basin lies in parts of 3 of the 

10 hydrologic areas identified by Giese and Mason 

(1993)—the Charlotte Belt and Milton Belt hydrologic 

area (HA9), the Carolina Slate Belt (argillite zone) 

hydrologic area (HA8), and the Triassic Basin 

hydrologic area (HA6; fig. 2). The Charlotte and 

Milton Belts consist predominantly of igneous, 

metaigneous, and metavolcanic rocks, which yield 

more water to wells than rocks in the Carolina Slate 

Belt and Triassic Basin (Daniel, 1989; Giese and 

Mason, 1993). The potential for sustained base flows in 

streams in the Charlotte and Milton Belts is considered 

intermediate (or moderate) relative to the other 

hydrologic areas in the State. Many streams in the 

Carolina Slate Belt and Triassic Basin hydrologic areas 

have 7Q10 discharges close to zero as a result of low 

permeabilities associated with rock types in these 

areas. Thus, streams in the Carolina Slate Belt and 

Triassic Basin have little to no potential for sustained 
6 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002

Figure 2. Hydrologic areas of similar potential to sustain low flows in North Carolina.

base flow relative to the other hydrologic areas in the 

State. As will be discussed in subsequent sections, unit 

low-flow discharges (expressed as cubic feet per square 

mile of drainage area) at streams in the Rocky River 

basin were noted to decrease in the downstream 

direction, generally concurrent with changes in the 

underlying geologic characteristics.

Drainage System

Rivers and streams in the Rocky River basin 

constitute one of the units defined in the system of 

hydrologic units in the USGS National Water Data 

Network (Seaber and others, 1987). The unit is 

identified as “03040103 Rocky [River], North 

Carolina” and defines the study area for this report. 

Selected gaging stations and measurements at sites in 

this basin are the basis for the low-flow characteristics 

and profiles presented in this report.

Major Rivers and Tributaries

The Rocky River begins near Mooresville in 

Iredell County and extends nearly 91 miles (mi) from 

the headwaters to the mouth of the river. From the 

headwaters, the Rocky River flows southeast through 

Iredell and Cabarrus Counties, turns south in southeastern Cabarrus County, and then constitutes the 

county boundary between Stanly and Anson Counties 

and Stanly and Union Counties before merging with 

the Yadkin River to form the Pee Dee River (pl. 1).

The drainage area of the Rocky River at its 

mouth is 1,413 mi2. The basin gradually broadens in 

width as the river flows downstream from the 

northwest to the southeast. Major tributaries draining to 

the Rocky River include Clarke Creek (28.2 mi2

) and 

Mallard Creek (41.2 mi2) in Mecklenburg and 

Cabarrus Counties; Coddle Creek (78.8 mi2

) in Iredell 

and Cabarrus Counties; Irish Buffalo/Coldwater Creek 

(110 mi2) and Dutch Buffalo Creek (99 mi2) in Rowan 

and Cabarrus Counties; Long Creek (200 mi2

) in 

Stanly County; and Richardson Creek (234 mi2

) and 

Lanes Creek (135 mi2) in Union and Anson Counties 

(pl. 1).

Major Flow Modifications

Major flow modifications are an important factor 

affecting low-flow characteristics. Flow modifications 

can be classified in two general categories—

impoundments and flow diversions. The ongoing 

addition and, in some instances, removal of these 

modifications results in continual changes in the lowflow characteristics and renders an additional level of 

complexity to the efforts in determining low-flow 

characteristics.

Impoundments

Impoundments are formed when dams are 

constructed on streams to store water for a variety of 

purposes, including water supply, recreation, irrigation, 

and cooling water. The effects of impoundments on 

downstream low-flow characteristics vary. Changes in 
Description of the Rocky River Basin 7

streamflow patterns can occur when water is stored, 

when water is diverted (for supply purposes—a 

common occurrence in impoundments), and to a 

smaller extent, when water evaporates from 

impoundments. Post-impoundment flow durations for 

downstream flows, particularly below major 

impoundments, generally are different from preimpoundment conditions. The most common, and 

usually most obvious, difference is the reduction in 

peak discharges observed in post-impoundment flows. 

Some impoundments also serve to augment 

downstream flows during droughts and, thus, increase 

low flows observed below a dam relative to preimpoundment conditions.

Approximately 175 impoundments with dams 

having structural heights exceeding 15 ft were 

identified in the Rocky River basin (North Carolina 

Department of Environment, Health, and Natural 

Resources, unpub. data, 1993). Many are privately 

owned impoundments having relatively small surface 

areas at the spillway level. These impoundments 

primarily are used as (1) farm ponds, which provide 

water for irrigation and help reduce sediment 

discharges to streams; (2) recreational lakes at 

campgrounds and park facilities; and(or) (3) landscape 

features (ponds) in developed areas.

A number of impoundments in the Rocky River 

basin cause widespread inundation of the river valley 

upstream from the dam. The impoundment having the 

largest surface area is Lake Howell, formerly known as 

Coddle Creek Reservoir (1,300 acres), in Cabarrus 

County (pl. 1; North Carolina Department of 

Environment, Health, and Natural Resources, 1992). 

Completed in 1993, Lake Howell drains approximately 

47 mi2 of Coddle Creek. Other impoundments having 

surface areas greater than 200 acres or serving as watersupply sources for the larger municipalities in the 

Rocky River basin are listed in table 1.

Minimum-flow releases are assigned to some 

dams to ensure that a sustained level of flow occurs 

in the stream reaches below the dams. In North 

Carolina, State agencies that may be involved in 

the determination and assignment of minimum-flow 

releases are the North Carolina Division of Land 

Resources (Dam Safety Program), Division of 

Water Resources, Division of Water Quality, Wildlife 

Resources Commission, and on rare occasions, the 

North Carolina Utilities Commission (James Mead, 

North Carolina Division of Water Resources, oral 

commun., June 13, 2003). Federal agencies that may be 

involved in the determination of minimum-flow 

releases are the Federal Energy Regulatory 

Commission, U.S. Fish and Wildlife Service, U.S. 

Forest Service, U.S. Army Corps of Engineers, and the 

National Marine Fisheries Service. Determinations of 

minimum-flow releases are made to address issues 

concerning available downstream flows and 

maintenance of water quality and aquatic habitats.

Minimum-flow releases can occur in one of two 

forms—a release based on operations that involve the 

opening and closing of gates at the dam to adjust 

magnitudes of discharges, or a release based on the 

structural characteristics of the dam’s flow-release 

system, such as a riser-barrel orifice commonly found 

in smaller impoundments. Only one lake in the Rocky 

River basin has an assigned minimum-flow release. 

Lake Howell presently has a minimum-flow release of 

6.0 ft3

/s (James Mead, North Carolina Division of 

Water Resources, oral commun., June 24, 2002). 

However, minimum releases as low as 2.0 ft3/s from 

the dam to Coddle Creek were allowed during the 

recent (1998–2002) drought conditions observed 

across North Carolina, consisting of 1.0 ft3/s from the 

dam and 1.0 ft3/s from filter backwash associated with 

water-treatment operations downstream from the dam. 

Presently (2003), a tiered set of minimum releases is 

being considered to allow for flexibility in adjusting 

minimum releases during low-flow conditions (James 

Mead, North Carolina Division of Water Resources, 

oral commun., April 9, 2003).

No other lakes were identified as having 

minimum-flow releases in the Rocky River basin 

(James Mead, North Carolina Division of Water 

Resources, oral commun., June 24, 2002). Variations in 

the presence of minimum-flow releases at 

impoundments in the basin apparently reflect the ages 

of dams more than any other factor. Increased 

awareness of environmental concerns in recent decades 

has resulted in revised procedures for maintaining 

downstream flows. The effect of having no minimumflow release at an impoundment would mean that flows 

could potentially decrease to zero flow in the reaches 

immediately downstream from the dam depending on 

the seepage characteristics through the dam. Thus, for 

low-flow characteristics at downstream locations on an 

impounded stream, the effect could be flows that are 

equivalent to those at nearby locations having drainage 

areas equal to the intervening drainage area between 

the dam and a downstream location.
8 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002 Table 1. Summary of selected impoundments and minimum-flow releases in the Rocky River basin in North Carolina [mi2, square miles; ft3/s, cubic feet per second; —, no minimum-flow release specified. Impoundments are listed in general downstream order and have surf

as water-supply sources for the larger municipalities in the Rocky River basin] County Impoundment name Stream Drainage area, (mi2

)

Year of 

completiona

a North Carolina Department of Environment, Health, and Natural Resources, 1992.

Surface 

areaa, 

(acres)

Minimumflow 

releaseb

(ft3/s)

b James Mead, North Carolina Division of Water Resources, oral commun., June 24, 2002.

R

Cabarrus Lake Don T. Howell

(formerly Coddle Creek Reservoir)

Coddle Creek 47c

c Approximate drainage area.

1993 1,300 6.0 Minimum-flow release 

minimum releases to recent drought condilow as 2.0 ft3/s, cons

and 1.0 ft3/s from filtwith water-treatmemdownstream from the tiered set of minimum investigated for this d

d James Mead, North Carolina Division of Water Resources, oral commun., April 9, 2003.

Rowan Kannapolis Lake Irish Buffalo Creek 10.4 1938 289

— Lake is kept full by pu

in adjacent South Ya

Howell in Cabarrus Cowned but serves as the city of Kannapoli

Cabarrus Lake Fisher Coldwater Creek 18.9 1948 277

—

Cabarrus Lake Concord Reedy Branche

e Other stream names for this impoundment have been identified as Patterson Branch (Powell, 1968) and Chambers Branch (North Carolina Departme

Natural Resources, 1992).

4.7c 1926f

f Powell, 1968.

85f —

Union Lake Monroe Little Richardson 

Creek

9.3c 1955 140

—

Union Lake Lee Richardson Creek 51.2 1927 125

—

Union Lake Twitty (formerly Lake 

Stewart)

Stewarts Creek 35.4 1972 82

— Stewarts Creek is tribu
Description of the Rocky River Basin 9

Diversions

Diversions, collectively defined in this report as 

water-supply withdrawals and return point-source 

discharges, have the effect of immediately altering 

downstream low flows by an amount equal to the 

diversion rate. Withdrawals commonly are made by 

municipalities and by some major industries. 

Additionally, some withdrawals are made for 

agricultural and livestock operations. Until 1999, the 

State of North Carolina required registration of all 

withdrawals equal to or exceeding 1 million gallons per 

day (Mgal/d), or approximately 1.5 ft3/s. Changes in 

State legislation, however, now require registration of 

non-agricultural withdrawals equal to or exceeding 

100,000 gallons per day (approximately 0.15 ft3

/s); 

agricultural withdrawals exceeding 1 Mgal/d must be 

registered (Woodrow L. Yonts, North Carolina 

Division of Water Resources, oral commun., 

September 2000). In the Rocky River basin, a total of 

40 registered withdrawals were identified (http://

www.dwr.ehnr.state.nc.us/, maintained by the North 

Carolina Division of Water Resources, accessed April 

11, 2003). Because the State requires that decreased 

flows downstream from withdrawals must be sufficient 

to sustain downstream uses during drought conditions, 

including the assimilation of treated effluent, 

knowledge of low-flow characteristics is important.

Point-source discharges to streams are permitted 

through the issuance of National Pollutant Discharge 

Elimination System (NPDES) permits. In North 

Carolina as well as in other States, permits that set 

limits for discharges of treated effluent are based, in 

part, on the 7Q10 discharge. In a similar manner to 

withdrawals, flows upstream from the discharge point 

must be sufficient to assimilate the treated effluent 

while maintaining other uses of the stream. As of 2002, 

the DWQ issued about 60 NPDES permits for pointsource discharges to more than 55 facilities and 

municipalities in the Rocky River basin (Betsy 

Albright, North Carolina Division of Water Quality, 

unpub. data, February 20, 2002). The number of 

NPDES permits continuously changes as a result of the 

addition and rescission of permitted discharges in the 

basin. Among the NPDES permits in the basin, 

5 permit holders (all municipal) are designated by the 

DWQ as major dischargers. The major dischargers are 

generally defined as facilities discharging more than 

1 Mgal/d or facilities having discharges that include 

high levels of toxicants or metals (Charles Weaver, 

North Carolina Division of Water Quality, oral 

commun., July 2000).

Data describing major withdrawals and pointsource discharges in the study area were obtained from 

the different State agencies that monitor flow 

diversions (North Carolina Department of 

Environment, Health, and Natural Resources, written 

commun., 2001) and from local water-treatment and 

wastewater-treatment operators. For selected facilities, 

average surface-water withdrawals and return pointsource discharges reported for 2001 were compiled into 

a summary that lists the magnitudes of streamflow 

changes in the affected streams (table 2). In some 

instances, point-source discharges were paired with a 

corresponding surface-water withdrawal made by a 

given facility. For each facility, the NPDES permit 

number and permitted flow rate assigned to the permit 

also are listed. Due to changes in growth and 

subsequent demands, the amounts of withdrawals and 

the point-source discharges vary over time. Also, given 

that hydrologic conditions during 2001 (the most 

recent calendar year when the information was 

compiled) were low due to effects of a drought that 

occurred during 1998–2002, the amounts should not be 

considered reflective of normal conditions. 

Nevertheless, the information compiled for 2001 

provides a snapshot of the varying magnitudes of 

diversions that occur in the basin.

The withdrawals and point-source discharges 

occurring in the Rocky River basin are characterized by 

a series of interconnections among many of the 

municipalities. The largest withdrawals in the basin are 

made by the cities of Concord and Kannapolis, which 

obtain water from several nearby reservoirs (table 2). In 

2001, the withdrawals by Concord and Kannapolis 

averaged 9.8 and 6.1 Mgal/d (15.2 and 9.4 ft3

/s), 

respectively. The largest point-source discharge in the 

basin is made by Cabarrus County, which treats 

wastewater for a number of municipalities in the county 

including Concord and Kannapolis. This point-source 

discharge to the Rocky River, which occurs just 

upstream from the confluence with Irish Buffalo Creek, 

averaged 16.3 Mgal/d (25.2 ft3/s) in 2001 (table 2).

Other significant diversions are point-source 

discharges made by the town of Mooresville and by 

Charlotte-Mecklenburg Utilities into tributaries of the 

Rocky River. Mooresville discharges treated 

wastewater, which averaged 2.4 Mgal/d (3.7 ft3/s) in 

2001 (table 2), into Dye Branch just upstream from its 

mouth. Similarly, Charlotte-Mecklenburg Utilities 
10 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002

Table 2. Summary of selected surface-water withdrawals and return point-source discharges to streams in the Rocky River basin, 

North Carolina, 2001

[Mgal/d, million gallons per day (1 Mgal/d is equivalent to approximately 1.5 cubic feet per second); NPDES, National Pollutant Discharge Elimination 

System; N/A, not applicable; N/L, not limited; WTP, water-treatment plant; WWTP, wastewater-treatment plant. Facilities are listed in general downstream 

order in the Rocky River basin. For streams profiled in this report, river miles to the nearest tenth are listed in parentheses beside stream names. For 

municipalities having multiple withdrawals and(or) point-source discharges, the sum of withdrawals should be compared against the sum of point-source 

discharges for more meaningful comparisons. Where point-source discharge(s) is greater than withdrawal amount(s) for some municipalities, these facilities 

treat wastewater for nearby smaller municipalities]

County Municipality

or facility name

Purpose of 

water supply

Source of 

water supply

Average withdrawal 

(Mgal/d)

Destination of

point-source

discharge

Average point-source 

discharge (Mgal/d)

NPDES

permit

number

Permitted NPDES

discharge (Mgal/d)

Iredell Town of 

Mooresville

Public water supply Lake Norman in 

Catawba River basin

3.5 Dye Branch 2.4 NC0046728 5.2

Mecklenburg River Run 

Country Club, 

Inc.

Public water supply Supplied by CharlotteMecklenburg 

Utilities

N/A West Branch 

Rocky River

0.13 NC0067920 0.30

Mecklenburg CharlotteMecklenburg 

Utilities

Public water supply Mountain Island 

Lakea

 in Catawba 

River basin

98.3 Mallard Creeka 6.0 NC0030210 6.0

Cabarrus City of Concord Public water supplyb Lake Don T. Howell

(formerly Coddle 

Creek Reservoir)

Lake Concord

Lake Fisher

4.6

2.0

3.2

Coddle Creekc 0.55 NC0083119 0.60

Cabarrus Cabarrus Woods 

Community

Public water supply Ground-water wells 0.40 Reedy Creek 0.30 NC0035033 0.45

Cabarrus Bradfield Farms 

Community

Public water supply Ground-water wells 0.24 McKee Creek 0.15 NC0064734 0.46

Cabarrus City of 

Kannapolis

Public water supply Kannapolis Laked 6.1 Irish Buffalo 

Creekc 0.58 NC0006220 N/L

Cabarrus Water and 

Sewer 

Authority of 

Cabarrus 

County

Public water supply No withdrawale N/A Rocky River

(river mile 

56.8)

16.3 NC0036269 24.0

Cabarrus City of Mount 

Pleasant

Public water supply Dutch Buffalo Creekf

Ground-water wells

0.28

0.04

N/Ac N/A N/A N/A

Union Hemby Acres 

Community

Public water supply Supplied by Union 

County

N/A North Fork 

Crooked 

Creek

0.10 NC0035041 0.30

Union Country Wood 

Community

Public water supply Supplied by Union 

County

N/A Goose Creek 0.09 NC0065684 0.09
Description of the Rocky River Basin 11

Union Union County 

Public Works 

Department

Public water supply Supplied by Catawba 

River WTP in Yadkin 

River basin

Supplied by Anson 

County Water 

System in Yadkin 

River basin

N/A

N/A

South Fork 

Crooked 

Creek

Clear Creek

Goose Creek

1.1

0.02

0.14

NC0069841

NC0069523

NC0072508

1.9

0.05

 

0.231

Stanly City of 

Albemarle

Public water supply Narrows (Badin) 

Resevior in Yadkin 

River basin

Tuckerton Resevoir in 

Yadkin River basin

4.0

3.3

Long Creek 9.6 NC0024244 16.0

Stanly Town of 

Oakboro

Public water supply Supplied by the Stanly 

County Utility 

Department

Ground-water wells

N/A

0.06

Long Creek 0.28 NC0043532 0.50

Union City of Monroe Public water supply Lake Twittyg 7.5 Richardson 

Creek 

Stewarts Creek

7.2

0.30

NC0024333

NC0080381

9.0

N/L

Stanly Town of 

Norwood

Public water supply Lake Tillery in Yadkin 

River basin

0.41 Rocky River

(river mile 

4.3)

0.50 NC0021628 0.75

a

 Charlotte-Mecklenburg Utilities also obtains water from Lake Norman in the Catawba River basin. Water from the two lakes is distributed throughout 

Mecklenburg County, which lies within the two basins (Catawba, 75 percent; Rocky, 25 percent). No information is known concerning the percentage of the 

water supply used in Mecklenburg County that drains to the Rocky River. In addition to the Mallard Creek WWTP, the utility has other facilities for the 

discharge of treated wastewater into streams throughout Mecklenburg County in the Catawba River basin. Based on information submitted to the North 

Carolina Division of Water Resources under the 1997 Local Water Supply Plan program, the permitted discharge from the Mallard Creek WWTP represented 

about 7 percent of the total permitted discharges made by the utility (online database http://www.dwr.ehnr.state.nc.us/, maintained by the North Carolina 

Division of Water Resources, accessed April 9, 2003). b

The city of Concord obtains water supply from three sources. Water from Lake Howell is treated at the Coddle Creek Treatment Plant, and water from 

Lake Concord and Lake Fisher is treated at the Hillgrove Water Treatment Plant (Jeff Isley, City of Concord, oral commun., April 24, 2003). c

The cities of Concord, Kannapolis, and Mount Pleasant rely on the Water and Sewer Authority of Cabarrus County to treat and discharge most or all of 

their wastewater. dWater supply in Kannapolis Lake is supplemented by two other sources: Lake Howell in Cabarrus County and Second Creek in the adjacent South 

Yadkin River basin. In 2001, all water withdrawn from Kannapolis Lake came from Lake Howell (1.8 Mgal/d) and Second Creek (4.3 Mgal/d). e

The Water and Sewer Authority of Cabarrus County withdraws no water. The facility treats and discharges wastewater for the cities of Concord, 

Kannapolis, and Mount Pleasant. f

Based on information submitted to the North Carolina Division of Water Resources under the 1997 Local Water Supply Plan program, Mount Pleasant 

is also able to withdraw water from Black Run Creek Reservoir during emergencies (online database http://www.dwr.ehnr.state.nc.us/, maintained by the North 

Carolina Division of Water Resources, accessed April 9, 2003). g

The city of Monroe pumps an unmetered amount of water from Lakes Monroe and Lee into Lake Twitty for water-supply use.

Table 2. Summary of selected surface-water withdrawals and return point-source discharges to streams in the Rocky River basin, 

North Carolina, 2001 — Continued

[Mgal/d, million gallons per day (1 Mgal/d is equivalent to approximately 1.5 cubic feet per second); NPDES, National Pollutant Discharge Elimination 

System; N/A, not applicable; N/L, not limited; WTP, water-treatment plant; WWTP, wastewater-treatment plant. Facilities are listed in general downstream 

order in the Rocky River basin. For streams profiled in this report, river miles to the nearest tenth are listed in parentheses beside stream names. For 

municipalities having multiple withdrawals and(or) point-source discharges, the sum of withdrawals should be compared against the sum of point-source 

discharges for more meaningful comparisons. Where point-source discharge(s) is greater than withdrawal amount(s) for some municipalities, these facilities 

treat wastewater for nearby smaller municipalities]

County Municipality

or facility name

Purpose of 

water supply

Source of 

water supply

Average withdrawal 

(Mgal/d)

Destination of

point-source

discharge

Average point-source 

discharge (Mgal/d)

NPDES

permit

number

Permitted NPDES

discharge (Mgal/d)
12 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002

discharged an average of 6.0 Mgal/d (9.3 ft3/s) of 

treated wastewater during 2001 into Mallard Creek. 

These municipalities obtain their water supply from 

Mountain Island Lake and Lake Norman, respectively, 

in the adjacent Catawba River basin, indicating the 

presence of interbasin transfers to the Rocky River 

basin. The city of Monroe withdrew an average of 

7.5 Mgal/d (11.6 ft3/s) from Lake Twitty, an 

impoundment of Stewarts Creek, and returned a 

combined 7.5 Mgal/d (11.6 ft3

/s) to Richardson Creek 

in 2001 (table 2). Other smaller municipalities in the 

eastern part of the Rocky River basin obtain their water 

supply from impoundments of the Yadkin River

located east of the study area. The city of Albemarle

withdrew a combined average of 7.3 Mgal/d 

(11.3 ft3

/s) from Narrows and Tuckertown Reservoirs 

and returned 9.6 Mgal/d (14.9 ft3/s) to Long Creek, a 

tributary to the Rocky River (table 2). Water-supply 

withdrawals by the town of Norwood averaged about 

0.4 Mgal/d (about 0.6 ft3

/s) from Lake Tillery, and 

return discharges averaged about 0.5 Mgal/d (about 

0.8 ft3/s) to the Rocky River in 2001 (table 2).

Climate

The climate in the Rocky River basin, as 

throughout most of North Carolina, consists of long, 

hot, humid summers and short, mild winters with 

periods of more moderate conditions during the spring 

and autumn seasons. The average annual temperature 

(1961–90) in the study area is about 60 degrees 

Fahrenheit (° F) and ranges, on a monthly basis, from 

about 40 ° F in January to about 79 ° F in July (National 

Oceanic and Atmospheric Administration, 2001). In all 

areas of the Rocky River basin, temperature extremes 

in the summer reach levels exceeding 90 ° F for long 

periods of consecutive days.

Average annual precipitation (1961–90) in the 

study area ranges from nearly 46 inches (in.) at the 

Concord reporting station to about 48 in. at the Monroe 

and Albemarle reporting stations (National Oceanic 

and Atmospheric Administration, 2001). On a monthly 

basis, the highest amounts of rainfall occur during July 

and August, and the lowest monthly rainfall generally 

occurs during April. Most rainfall during the warmer 

months comes from isolated, convective-type storms 

that occur in the late afternoons and evenings as a result 

of daytime heating. Rainfall during cooler months is 

commonly from more organized frontal storms that 

cover broad areas of the region.

Since 1900, major droughts have occurred in 

North Carolina resulting in low flows throughout the 

Rocky River basin. The drought of longest duration 

affecting streams in the Rocky River basin occurred 

during 1950–57 (Zembrzuski and others, 1991). At 

Rocky River near Norwood (site 169, pl. 1) in Stanly 

County, the lowest annual 7-day minimum discharge 

(26 ft3

/s on October 7) and instantaneous discharge 

(17 ft3

/s on October 8) for the period of record 

(1929–2002) occurred during the fall of 1954 (Ragland 

and others, 2003).

While the 1950–57 drought was the longest in 

duration, the drought having the most intense effects on 

streamflow occurred during 1998–2002. At Rocky 

River near Norwood (site 169), no record low 7-day 

minimum or instantaneous discharge was set, but the 

lowest annual mean discharge of 406 ft3/s occurred 

during the 2002 water year, compared to nearly 

1,340 ft3

/s for the period of record (Ragland and others, 

2003). The lowest annual mean discharge for the period 

of record also occurred during the 2002 water year for 

nearby sites in the Rocky and Catawba River 

basins—Big Bear Creek near Richfield (site 113), 

Long Creek near Paw Creek (USGS station 0214290 in 

western Mecklenburg County in the Catawba River 

basin), McAlpine Creek at Sardis Road near Charlotte 

(USGS station 02146600 in southeastern Mecklenburg 

County in the Catawba River basin), and Twelve Mile 

Creek near Waxhaw (USGS station 02146900 in 

southwestern Union County in the Catawba River 

basin). 

Analysis of monthly rainfall data from the 

National Oceanic and Atmospheric Administration 

(NOAA) rain gages in Concord, Albemarle, and 

Monroe indicates that cumulative departures from 

spring 1998 through early fall 2002 ranged from 30 to 

45 in. (Ryan Boyles, State Climate Office of North 

Carolina, written commun., April 14, 2003). 

Considering that average annual rainfall for these 

locations ranges from 46 to 48 in., the cumulative 

departures are equivalent to a range of between 9 and 

12 months of rainfall that did not occur during the 

1998–2002 period.

Geology and Soils

An understanding of the geology and soils in the 

study area may provide some insight into the low-flow 

characteristics for streams in the Rocky River basin. 

Although these factors should be considered in any 
Description of the Rocky River Basin 13

analysis of low flows, identification of an underlying 

geologic unit or soil cannot be used solely to determine 

the potential for sustaining base flow during drought 

conditions.

The Rocky River basin spans two of the major 

geologic belts in North Carolina—the Charlotte Belt 

and the Carolina Slate Belt. The Charlotte Belt region 

underlies the upper half of the basin in the counties of 

Iredell, Rowan, Mecklenburg, and Cabarrus. The 

Charlotte Belt consists largely of intrusive igneous 

rocks, both felsic and mafic, that range in age from 

300 to 500 million years and include granite, diorite, 

and gabbro (North Carolina Geological Survey, 1991). 

The Rocky River flows through the middle of the 

Concord ring dike, which consists of a ring of syenite 

surrounding a gabbro pluton, before exiting the 

Charlotte Belt region and flowing into the Carolina 

Slate Belt.

The portion of the Rocky River basin that is 

underlain by the Carolina Slate Belt includes Stanly, 

Union, and Anson Counties. The Carolina Slate Belt is 

composed of the remnants of a former chain of volcanic 

islands (North Carolina Geological Survey, 1991). 

Thus, the rocks in this part of the basin are primarily 

metamorphic and have sedimentary and volcanic 

origins. The rocks of the Carolina Slate Belt range in 

age from 550 to 650 million years (North Carolina 

Geological Survey, 1991). Specific rock types found in 

this portion of the basin include metamorphosed 

mudstone, argillite, and graywacke, and metavolcanic 

flows and tuffs (North Carolina Geological Survey, 

1985).

Twelve major soil series are present directly 

adjacent to the Rocky River and its tributaries. As with 

the geology, the soils of the Rocky River basin can be 

divided into three general categories: (1) piedmont 

upland, (2) lowland and intermediate, and (3) flood 

plain. The soils generally reflect the underlying 

geologic parent material with a mixture of soils derived 

from crystalline rock and soils derived from finegrained Carolina Slate rock present throughout the 

basin. The dominant soil texture among the 12 soil 

series is loam with a high occurrence of loam 

combination textures, including sandy loam, silt loam, 

and clay loam. The silt loam is the most common 

series, and 2 of the 12 series are clay soils. In general, 

all of the soils are considered moderately permeable 

(0.6 to 2 in. per hour).

Piedmont upland soils (Badin, Goldston, Enon, 

and Poindexter series) include soils present on slopes 

and knolls that generally are well drained with slopes 

ranging from 2 to 45 percent (U.S. Department of 

Agriculture, 1996). Soil textures range from clay to 

sandy loam. The Badin and Goldston series are by far 

the most prevalent upland soils, present along almost 

the entire reach of the Rocky River. Both Enon and 

Poindexter soils are found on gentle to steep slopes. 

The Badin series consists of clayey soils weathered 

from fine-grained Carolina Slate graywacke and 

argillite and is found on gentle to steep upland slopes 

(U.S. Department of Agriculture, 1996). The Goldston 

series, which has a silt loam texture, also is weathered 

from the Carolina Slate rocks and found on slopes and 

knolls; however, the Goldston series tends to be 

shallower than the Badin series. The Enon series 

consists of a sandy loam soil, and the Poindexter series 

consists of loam (U.S. Department of Agriculture, 

1988).

The lowland and intermediate soils (Coronaca, 

Cullen, Kirksey, and Misenheimer series) are found on 

flood plains, broad ridges, depressions, and heads of 

drainageways (U.S. Department of Agriculture, 1988). 

These soils range from well drained to poorly drained, 

and their slopes range from 0 to 15 percent (U.S. 

Department of Agriculture, 1988). The Coronaca and 

Cullen series are clay loams with slopes ranging from 

2 to 15 percent; both series are weathered from 

crystalline rocks that include gneiss, gabbro, and 

diorite (U.S. Department of Agriculture, 1988). The 

Misenheimer and Kirksey series are moderately well 

drained, have slopes ranging from 0 to 4 percent, and 

are silt loams weathered from argillites and graywacke 

sandstones (U.S. Department of Agriculture, 1988).

Flood-plain soils of the Rocky River basin have 

slopes that range from 0 to 2 percent and include the 

Chewacla, Congaree, Oakboro, and Wehadkee series 

(U.S. Department of Agriculture, 1988, 1989). The 

Chewacla and Wehadkee series are the most prevalent 

flood-plain series and are poorly drained alluvium 

weathered from crystalline rocks such as schist, gneiss, 

and granite (U.S. Department of Agriculture, 1988). 

The Oakboro series is a silt loam alluvium that is well 

drained and weathered from various Carolina Slate 

rocks such as slate, siltstone, and tuff (U.S. Department 

of Agriculture, 1989). The fourth flood-plain series, the 

Congaree, is a fine sandy loam alluvium that is well 

drained, like the Oakboro series, but is formed from 
14 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002

crystalline rock (U.S. Department of Agriculture, 

1989).

While low-flow characteristics cannot be 

described solely on the basis of knowing the geology 

and soils of a given area, average well yields 

determined for different hydrogeologic units in the 

Piedmont and Blue Ridge Provinces of North Carolina 

provide yet another indicator of the potential for 

sustained base flow. Daniel (1989) identified 18 

hydrogeologic units in the Blue Ridge and Piedmont 

Provinces of North Carolina and determined an average 

well yield for each unit. The average well yield for all 

18 of the hydrogeologic units was 18.2 gallons per 

minute (gal/min), equivalent to 0.040 ft3

/s. In the 

Rocky River basin, 12 of the 18 hydrogeologic units 

were identified. Seven of the 12 units, composing 

nearly 64 percent of the Rocky River basin (Daniel and 

Payne, 1990; fig. 3), have well yields less than this 

average. Six of the seven units having less-thanaverage well yields are derived from igneous and 

metavolcanic rocks, and among this group is the unit 

characterized by argillite rocks (ARG unit, fig. 3), 

which covers nearly 48 percent of the basin. The 

average well yield of argillite rocks is 14.6 gal/min (or 

0.032 ft3/s), which is significantly below the average of 

18.2 gal/min as determined by Daniel (1989). The 

seventh unit, which covers less than 1 percent of the 

Rocky River basin, is characterized by Triassic rocks 

(TRI unit, fig. 3) and has the lowest average well yield 

(14.6 gal/min, or 0.025 ft3/s) of all the hydrogeologic 

units studied by Daniel (1989).

Land Use

Land-use information for the study area was 

obtained from the Multi-Resolution Land 

Characteristics data set, a product of the Ecological 

Monitoring and Assessment Program of the U.S. 

Environmental Protection Agency (USEPA) and other 

agencies, including the U.S. Forest Service, NOAA, 

and the USGS (Eimers and others, 1999). The USEPA 

land-cover information was collected by the Landsat 

Thematic Mapper sensor using remote-sensing 

techniques (Vogelmann and others, 1998) and 

compiled from aerial photographs taken primarily 

during the spring seasons of 1991–93. Information was 

processed into 15 land-use classes established for the 

development of a consistent and generalized land-cover 

data base for all of the United States (Vogelmann and 

others, 1998). In the Rocky River basin, 6 general 

categories were identified from the 15 land-use classes 

in the study area (table 3).

Overall, most of the land use in the Rocky River 

basin is rural with forested and agricultural land uses 

occupying about 91 percent of the basin. Urban land 

uses (low- and high-density residential, high-density 

commercial, industrial, and transportation uses) 

compose 7.3 percent of the basin. Concord and 

Kannapolis in Cabarrus and Rowan Counties, 

respectively, compose the greatest extent of urban land 

use in the basin. A large extent of urban land use also 

occurs on the western border of the basin near 

Charlotte and its suburbs. Other municipalities in the 

basin include Mooresville in Iredell County, Albemarle 

in Stanly County, and Monroe in Union County (pl. 1).

Changes in land use and effects on low flows in 

North Carolina generally have not been investigated 

extensively. Only two continuous-record gaging 

stations with long-term records of discharge (sites 113 

and 169) are located in the Rocky River basin; however, 

land use in the basins upstream from these sites is 

generally rural, thereby precluding any insight into the 

effects of land-use changes on low-flow characteristics. 

As previously discussed, Evett (1994) investigated the 

effects of urbanization and land-use changes on low 

flows. While the conclusions from that investigation 

tended to support the hypothesis of decreasing low 

flows with increasing urbanization, Evett (1994) 

described the results as being statistically inconclusive. 

Table 3. Land use in the Rocky River basin

in North Carolina

Land-use category

Percent of study area 

covered by 

land-use 

categorya

a

 From U.S. Environmental Protection Agency LandCover Data Set (Vogelmann and others, 1998).

Developed (includes urban 

areas)

7.3

Agricultural 40.4

Forested 50.3

Water 0.5

Wetlands 1.0

Barren (includes quarries, 

gravel pits, and transitional 

areas such as clear-cut areas)

0.5

Totals 100.0
Description of the Rocky River Basin 15

Figure 3. Hydrogeologic units in the Rocky River basin, North Carolina.
16 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002

Nevertheless, speculation among hydrologists has been 

that increasing urbanization results in decreased low 

flows due to less infiltration of water to shallow 

aquifers. In other words, the runoff from impervious 

areas is directed toward stream channels for immediate 

removal; thus, little or no storage of water occurs in the 

soils for later release during periods of low flow. As 

developed areas in North Carolina’s larger 

municipalities continue to expand, additional 

investigations may aid in the understanding of land-use 

effects on low-flow hydrology.

LOW-FLOW CHARACTERISTICS IN THE ROCKY 

RIVER BASIN

Low-flow characteristics were determined for 

selected streamflow sites in the Rocky River basin 

study area in North Carolina. Available records of 

streamflow collected through the 2002 water year for 

continuous-record gaging stations and through the 

2001 water year for partial-record measuring sites were 

compiled for 173 sites (table 4, p. 41–50; pl. 1) and 

evaluated to identify sites where low-flow 

characteristics could be determined. The period of 

record varies from site to site. Of the 173 sites, 8 are 

continuous-record gaging stations, 161 are partialrecord sites, and 4 are sites having a combination of 

continuous- and partial-record discharges. The lowflow characteristics for selected sites in the Rocky 

River basin are presented in this section.

Continuous-Record Stations

Low-flow characteristics based on continuous 

records of discharge were developed for 12 sites—

8 continuous-record gaging stations and 4 sites that 

have both continuous- and partial-record discharges. 

Available records of discharge collected through the 

2002 water year were used in the analyses. The 

magnitude and frequency of low flows for the 

continuous-record gaging stations are given in table 5.

Estimates of low-flow discharges for two 

continuous-record sites (113, 169) having more than 

10 years of record were developed by using frequency 

curves (Riggs, 1972; fig. 4). The curves depict the 

relation between recurrence interval and the lowest 

average annual discharge for a specified number of 

days at a gaging station. Using available periods of 

record, frequency curves of measured annual (climatic 

year) 7-day and 30-day lowest average discharges and 

winter (November through March) 7-day lowest 

average discharge were developed; then a log-Pearson 

Type III frequency distribution was fitted to the 

measured values. The computed log-Pearson 

distribution generally corresponds closely to the 

distribution of annual low flows for sites having longterm periods of record (fig. 4). The method of analysis 

for these sites is denoted as “LP” in table 5.

The remaining 10 gaging stations have periods of 

record less than 10 years (and usually less than 5 years) 

and were treated as partial-record measuring sites by 

using the methods of correlation described in the 

subsequent section Partial-Record Sites. The method of 

analysis for these sites is denoted as “C” in table 5. The 

period of analysis for these sites is denoted as “PR” 

representing application of methods used at partialrecord sites, and the available period of record listed in 

table 4 was included in the analyses.

In the determination of low-flow characteristics 

for continuous-record gaging stations, the available 

periods of record were used in the analyses. Due to the 

short and varying periods of records at most 

continuous-record sites, no common period of record 

could be identified for use in the analyses. Doing so 

would have removed some sites from the compilation 

of low-flow characteristics or limited the amount of 

data available for inclusion in the analyses.

The last year of data collection for a discontinued 

site on Richardson Creek was 1944 (site 146, table 5), 

and low-flow characteristics (table 5) for this site 

cannot necessarily be interpreted as reflecting low-flow 

characteristics that would be calculated if the gage 

were still in operation. Changes in basin 

characteristics, such as development, artificial 

drainage, and(or) flow modifications, could result in 

changes in low-flow characteristics. Thus, when 

examining the low-flow characteristics for any 

discontinued site, the period of record should be 

considered, particularly in basins that have experienced 

major changes. More recent data are needed to provide 

a better understanding of the current low-flow 

characteristics.

Streamflows on the Rocky River, particularly in 

the reaches upstream from Stanfield (pl. 1), are affected 

by major flow diversions in the form of NPDES pointsource discharges. The low-flow characteristics 

determined for the continuous-record gaging stations 

near Rocky River, Stanfield, and Norwood (sites 40, 

85, and 169, respectively; table 5) reflect, to varying 

degrees, the effects of these major diversions, all of 
Low-Flow Characteristics in the Rocky River Basin 17

Table 5. Magnitude and frequency of annual low-flow characteristics at selected continuous-record gaging stations in the Rocky River 

basin in North Carolina

[USGS, U.S. Geological Survey; mi2, square miles; (ft3/s)/mi2, cubic feet per second per square mile; ft3/s, cubic feet per second; 7Q10, 7-day, 10-year low 

flow; 30Q2, 30-day, 2-year low flow; W7Q10, winter 7-day, 10-year low flow; 7Q2, 7-day, 2-year low flow. Flow regulation: U, unregulated flow; R, regulated flow. Method of analysis: C, estimates based on correlation techniques; LP, estimates based on log-Pearson frequency distribution. PR, gaging station 

having less than 10 years record of daily mean discharge, treated as a partial-record site where low-flow characteristics were developed by using correlation 

techniques; <, less than; NPDES, National Pollutant Discharge Elimination System. For each continuous-record site using the period of analysis (usually the 

available period of record), the number of daily discharges equal to zero or less than or equal to the indicated 7Q10 discharge are provided for informational 

purposes] Site index no. (pl. 1)

USGS downstream 

order number

Station name

Drainage area

(mi2

)

Period of analysis

Number of

 observed days 

of flow

Average annual unit 

flow [(ft3/s)/mi2

]

Low-flow characteristics

(ft3

/s)

Flow regulation

Equal to 

Method of analysis

zero flow

Less than or 

equal to 7Q10

7Q1030Q2

W7Q10

7Q2

21 02124149 Mallard Creek below Stony 

Creek near Harrisburg

34.6 PR 0 20 1.0 1.4 4.4 3.6 2.9 U C

40 0212433550 Rocky River above Irish 

Buffalo Creek near Rocky 

Rivera

a

 Includes effects of major NPDES discharge(s) upstream from gaging station.

278 PR 0 72 1.0 25.2 40.6 35.2 33.4 R C

68 02124471 Dutch Buffalo Creek at NC 49 

near Mount Pleasant

45.1 PR 15 47 1.0 0.7b

b

 Low-flow characteristics determined at other sites (65, 69, and 73) on Dutch Buffalo Creek suggest the existence of a losing reach in the downstream 

reaches.

3.3 2.2 1.9 U C

80 02124692 Goose Creek at Fairviewc

c

 Low-flow characteristics previously published in Giese and Mason (1993); where different, estimates in this report supersede previous estimates.

24.0 PR 0 15 1.0 0.3 1.4 1.0 0.8 U C

85 02124742 Rocky River near Stanfielda 628 PR 0 117 1.0 42.3 103 87.3 80.5 R C

113 02125000 Big Bear Creek near Richfieldc 55.6 Apr 1954–

Mar 2002

686 686 1.0 0 0.4 0.2 0.2 U LP

146 02125500 Richardson Creek near 

Marshville

163 PR 37 60 0.9 0.5d

d

 Low-flow characteristics reflect flow conditions prior to the opening of the water-treatment plant on Stewarts Creek just upstream from Richardson 

Creek in 1972 and the wastewater-treatment plant on Richardson Creek in 1965. See low-flow characteristics for other locations on Richardson Creek (sites 

124, 132, 139, 145, and 154 in table 6). Low-flow characteristics for this site (and any discontinued sites) cannot be interpreted as reflective of current lowflow characteristics in the absence of more recent data. In basins where significant land-use changes have occurred, available low-flow characteristics may be 

useful in the understanding of natural-flow conditions during periods of low flows prior to changes in the basin.

3.0 1.6 1.6 U C

152 02125557 Gourdvine Creek near Olive 

Branch

8.75 PR 121 121 0.9 0 0 0 0 U C

157 02125696 Lanes Creek near Trinity 4.92 PR 557 557 0.9 0 0 0 0 U C

159 02125699 Wicker Branch near Trinity 5.83 PR 4 4 0.9 0 < 0.05 < 0.05 0 U C

165 02125816 Lanes Creek near Marshville 87.7 PR 67 67 0.9 0e

e

 Low-flow characteristics for this site suggest the existence of a losing reach on Lanes Creek (see low-flow characteristics for site 157 in this table and 

site 161 in table 6).

0.3 0.05 < 0.05 U C

169 02126000 Rocky River near Norwooda 1,372 Apr 1930–

Mar 2002

0 152 1.0 45.8 113 77.6 78.2 R LP
18 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002

Figure 4. Low-flow frequency curve of annual minimum 7-day average discharges using log-Pearson Type III frequency 

distribution at Rocky River near Norwood, North Carolina (site 169).
Low-Flow Characteristics in the Rocky River Basin 19

which began in the late 1970’s and early 1980’s. At site 

40 near Rocky River, the drainage area is 278 mi2

. The 

combined drainage areas at the two major point-source 

discharge locations on Dye Branch and Mallard Creek 

(table 2) is nearly 43 mi2 (equivalent to about 15 

percent of the drainage area at site 40). In other words, 

the intervening drainage area, where the flows are not 

known to be affected by any other major diversions or 

regulation, between site 40 and the locations of the two 

NPDES discharge points is 85 percent of the total area 

upstream from site 40. However, during the period 

April 2000 through September 2002, the combined 

point-source discharges at these two locations averaged 

about 26 percent of the flows at site 40.

Similarly, the drainage area at site 85 near 

Stanfield is 628 mi2

. The combined drainage areas 

upstream from the three major point-source discharges 

on Dye Branch, Mallard Creek, and Rocky River 

(discharges by Cabarrus County, table 2) is 321 mi2

, or 

about 51 percent of the drainage area at site 85. During 

the period April 2000 through September 2002, 

however, the combined point-source discharges 

averaged about 34 percent of the flows at site 85.

The drainage area between the gaging stations 

near Stanfield (site 85) and near Norwood (site 169) 

increases from 628 to 1,372 mi2, a 118 percent 

increase. In this same reach, the 7Q10 discharge 

between the gaging stations increases from 42.3 to 

45.8 ft3/s, an 8.3 percent increase. However, the unit 

7Q10 discharge between Stanfield and Norwood 

decreases by about 50 percent in this same reach. The 

reach of the river and its tributaries between these two 

locations is underlain by the Carolina Slate Belt, a 

geologic region that is characterized by streams having 

very little to no potential for sustained base flow. 

At the gaging station near Norwood (site 169), 

the combined drainage areas upstream from the three 

major point-source discharges is about 23 percent of 

the drainage area at the gaging station, and the 

combined discharges averaged about 22 percent of the 

streamflows at the gaging station during April 2000 

through September 2002. The actual effects of the 

diversions on the flows at the gaging station near 

Norwood (site 169) are more difficult to ascertain 

because of the added effect of a possible losing reach 

downstream from the gaging station near Stanfield 

(site 85).

A losing reach occurs when streamflow in a 

channel discharges to the ground. During low-flow 

periods, streams are sustained by base flows, meaning 

the water table is higher than the channel bottom 

allowing ground water to discharge from the adjacent 

banks to the stream. However, if the water table is 

below the channel bottom, streamflow in the channel 

discharges to the water table, resulting in a stream with 

declining flows. Most streams in North Carolina are 

recognized as gaining reaches meaning that groundwater discharge to the stream aids the accumulation of 

flow in the downstream direction. Although a losing 

reach is characterized by declining flows, it is not 

characterized by decreasing unit low-flow discharges 

in the downstream direction. Where the unit flows 

between two points on a stream decrease by a 

substantial percentage, however, it is possible that the 

stream could be a losing reach if there are no major 

water-supply diversions between the two points. 

Conversely, the presence of a major water-supply 

withdrawal between two sites on the same stream 

requires caution in assessing the existence of a losing 

reach.

During the investigation, efforts were made to 

estimate low-flow characteristics at the Rocky River 

(site 40) and Stanfield (site 85) gaging stations that 

would be considered reflective of natural-flow 

conditions (that is, without the presence of the major 

NPDES discharges upstream from the site). Records of 

daily discharge for the period April 2000 through 

September 2002 were adjusted to account for the 

upstream point-source discharges to Dye Branch, 

Mallard Creek, and Rocky River (table 2). At site 40, 

the estimated 7Q10 discharge based on streamflows 

unaffected by the two upstream point-source 

discharges was 10.5 ft3/s, or about 0.04 (ft3

/s)/mi2. At 

site 85, the 7Q10 discharge based on streamflows 

unaffected by the three point-source discharges was 

estimated to be 23 ft3/s, or likewise about 0.04 (ft3/s)/

mi2. The natural-flow estimates (in terms of unit 

discharges) are about 40 to 50 percent of the estimated 

7Q10 discharges based on the presence of the pointsource discharges (table 5). These comparisons 

highlight the effect of these major flow diversions in 

the basin.

The estimated 7Q10 discharge (10.5 ft3

/s) at site 

40 based on unaffected streamflows is 25 percent lower 

than a previous 7Q10 discharge of 14 ft3/s determined 

for site 39, a discontinued partial-record measuring site 

located almost immediately upstream from site 40. 

Considering that two independent sets of streamflow 

records from differing periods of record were used to 

determine these 7Q10 discharges, these values could be 
20 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002

regarded as fairly comparable. Thus it is likely that the 

natural-flow 7Q10 discharge for the Rocky River above 

Irish Buffalo Creek may be about 10 to 15 ft3/s. 

Because the short period of record used in the analysis 

for site 40 reflects drought conditions, it is also possible 

that subsequent estimates of the natural-flow 7Q10 

discharge may increase if additional periods of data 

collection reflect normal conditions.

Partial-Record Sites

Using the techniques discussed by Riggs (1972), 

low-flow characteristics were determined for 44 of the 

161 partial-record sites in the Rocky River basin 

(table 6). In general, sites having 10 or more discharge 

measurements were included in the analysis. 

Exceptions included sites where low-flow 

characteristics previously have been published. Sites 

on the Rocky River for which low-flow discharges 

were necessary to develop discharge profiles also were 

included in the analysis of low-flow characteristics.

Among the 161 partial-record sites having 10 or 

more measurements, low-flow characteristics were not 

determined for 18 sites: (1) sites 10, 17, and 140 had 

mostly crest-gage (peak flood) partial-record 

measurements, (2) site 23 is immediately downstream 

from a major NPDES point-source discharge, 

(3) site 39 is adjacent to a continuous-record station, 

(4) sites 114 and 153 had discharge records that were 

combined with those at an adjacent site for subsequent 

analysis, and (5) sites 1, 42, 44–50, 79, and 106 had 

uncharacteristically high unit low-flow discharges 

either because of fairly high discharge records or 

apparent upstream diversions.

The periods of record (and correspondingly, the 

number of discharge measurements) varied among the 

partial-record measuring sites, ranging from as little as 

a few years to more than several decades. Due to the 

varying periods of records, no common period of 

record could be identified for use in the analysis. Doing 

so would have removed some sites from the 

compilation of low-flow characteristics or limited the 

amount of data available for inclusion in the analyses. 

Thus data based on the available period of record 

through the 2001 water year were included in the 

analyses for partial-record measuring sites. Exceptions 

to this occurred in the analyses for two sites (3 and 60) 

on the Rocky River where only data for periods since 

the start of major upstream NPDES point-source 

discharges were used.

Discharge measurements at the partial-record 

sites were correlated with concurrent flows at nearby 

index sites (typically continuous-record gaging 

stations) where low-flow characteristics had been 

determined (fig. 5). Index sites used in the correlation 

analysis of concurrent flows were, to the extent 

possible, selected based on proximity of the partialrecord and index sites, and similarity of relevant basin 

characteristics such as drainage area, topography, soils, 

and hydrogeology, which may include sites outside of 

the Rocky River basin.

Defining the relation between concurrent flows 

usually is accomplished with either statistical 

techniques or graphical interpretation based on a 

visually fitted line drawn through the concurrent flows 

(Riggs, 1972; U.S. Geological Survey, 1985). In this 

investigation, graphical interpretation was used to 

establish the relation between the concurrent flows for 

many of the sites.

At most partial-record sites, correlations of the 

discharge measurements with concurrent flows at 

multiple index sites yielded several relations from 

which estimates of low-flow discharges could be 

determined. Overall estimates of low-flow discharges 

(7Q10, 30Q2, W7Q10, and 7Q2) for each partialrecord site were determined as the average of the 

individual estimates derived from each correlation.

However, individually derived estimates from 

correlations that could not be satisfactorily defined 

(generally due to substantial scatter of observations) 

were not included in the average for overall estimates.

Low-flow characteristics for the partial-record 

measuring sites generally reflect unregulated 

conditions in the study area. However, discharge 

measurements at some sites on the Rocky River reflect 

effects of flow diversions made by several major 

upstream point-source discharges. In addition, some 

tributary streams, such as Mallard Creek, Long Creek, 

and Richardson Creek, also are affected by flow 

diversions on these streams (pl. 1). With the exception 

of sites 3 and 60 on the Rocky River where only 

measurements made since the start of major pointsource discharges were used, the presence of regulation 

and(or) minor flow diversions was not quantified and 

adjusted for in the records of discharge measurements 

at the partial-record measuring sites (table 6).

In addition to the losing reach on the Rocky 

River downstream from the gaging station near 

Stanfield (site 85), the compilation of low-flow 

characteristics also indicates the possibility of losing 
Low-Flow Characteristics in the Rocky River Basin 21

Table 6. Magnitude and frequency of annual low-flow characteristics at selected partial-record measuring sites in the Rocky River basin 

in North Carolina

[USGS, U.S. Geological Survey; mi2, square miles; water year, the annual period from October 1 to September 30 and identified by the year in which the 

period ends; (ft3/s)/mi2, cubic feet per second per square mile; ft3/s, cubic feet per second; 7Q10, 7-day, 10-year low flow; 30Q2, 30-day, 2-year low flow; 

W7Q10, winter 7-day, 10-year low flow; 7Q2, 7-day, 2-year low flow; SR, secondary road; <, less than; N/A, not available; NPDES, National Pollutant 

Discharge Elimination System. Unless otherwise noted, low-flow characteristics typically reflect flow conditions unaffected by major diversions and(or) 

regulation] Site index no. (pl. 1)

USGS downstream 

order number

Station name

Drainage area

(mi2

)

Period of analysis

water years) (

Number of

measurements

Average annual unit 

flow [(ft3/s)/mi2

]

Low-flow characteristics

(ft3

/s)

Flow

Zero flow

7Q1030Q2

W7Q10

7Q2

3 02123881 Rocky River near Davidson 13.4 1982–99, 2000, 2002 100a 0 1.05 4.6 7.6 6.9 6.4

5 02123932 South Prong West Branch Rocky 

River near Cornelius

4.98 1969–71, 1973–74 11 0 1.1 0.5 1.1 0.9 0.9

6 02123953 Rocky River near Caldwellb 39.0 1948, 1952-53, 

1961-62, 1971, 

1973–74

16c 0 1.1 6.1 11.1 9.3 9.1

9 02124050 South Prong Clarke Creek near 

Huntersville

5.75 1969–71, 1973, 1975 12 0 1.1 0.6 0.9 0.8 0.7

12 02124080 Clarke Creek near Harrisburgd 21.9 1951–71, 1988 45 0 1.1 1.0 3.0 2.3 2.1

15 02124110 Rocky River near Roberta Millb 87.2 1952–58, 1961–62, 

1967, 1973–74, 

1979, 2002

27 0 1.1 6.6 16.2 11.7 11.8

18 02124140 Toby Creek near Newell 3.6 1969–71, 1973, 1975 12 0 1.1 0.1 0.4 0.3 0.3

20 0212414860 Stony Creek at U.S. Highway 29 

near Harrisburg

6.71 1969–71, 1973, 1975 10 0 1.1 0 0.1 < 0.05 < 0.05

24 0212418255 Rocky River at SR 1304 near 

Harrisburgb 134 1956, 1961–62, 

1970–73, 1975, 

2002

12e 0 1.1 9.0 25.5 18.3 17.9

28 02124230 Coddle Creek near Concordf 57.9 1949–58, 1961–63 22 0 1.05 5.6 12.7 9.0 9.2

34 0212430295 Reedy Creek at SR 2804 near 

Wilgroved 12.7 1969–71, 1973, 1975 12 0 1.05 1.3 2.9 2.2 2.1

36 0212430645 McKee Creek at SR 2808 near 

Wilgroved 4.08 1969–71, 1973, 1975 11 0 1.05 0.2 0.7 0.4 0.4

37 02124320 Reedy Creek at Rocky Riverd 30.9 1955–63, 2002 26 0 1.05 1.6 3.8 3.0 3.0

51 02124374 Irish Buffalo Creek near 

Faggarts Crossroads

45.5 1974–84, 1986–99, 

2000, 2002

87 0 1.05 3.1 9.8 8.2 7.1

60 02124401 Rocky River near Flows Store 392 1980-99, 2000, 2002 54g 0 1.05 34.9 84.4 68.2 63.2

65 02124460 Dutch Buffalo Creek near 

Rimerd 33.8 1964–71, 1988 18 0 1.05 0.6 2.6 1.6 1.6

69 02124500 Dutch Buffalo Creek at Mount 

Pleasant

65.4 1953, 1955, 1961–

62, 1970–71, 1973, 

1975

10 0 1.05 1.1 4.7 2.9 2.8

73 02124596 Dutch Buffalo Creek at 

Georgeville

98.2 1948, 1952–53, 

1961–62, 1986–96, 

2002

33 0 1.0 N/Ah 4.4 3.0 2.3

86 02124745 North Fork Crooked Creek near 

Fairviewd 16 1961–62, 1965–69, 

1971

16 1 1.0 0 0.5 0.2 0.1

92 02124776 Rock Hole Creek at Stanfield 7.55 1970–71, 1973–75 10 0 0.95 0 0.1 < 0.05 < 0.05
22 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002

94 02124781 Rocky River at State Highway 

200 near Stanfieldb 708 1971, 1973–77, 2002 22 0 0.95 47.8 96.4 77.8 70.8

97 02124798 Rocky River at State Highway 

205 near Oakborob 744 1971, 1973-74 5 0 0.95 N/Ai 95.0 64.0 62.0

98 02124813 Rocky River near Oakborob 763 1961-62, 1970-71, 

1973-74, 2002

13 0 0.95 46.0 91.7 68.0 66.7

99 02124823 Long Creek at SR 1454 near 

Richfield

5.29 1974–84 54 7 1.0 0 < 0.05 < 0.05 < 0.05

101 02124835 Long Creek near Plylerd 27.5 1955-56, 1961-62, 

1964-67

10 0 1.0 0.2 1.3 0.7 0.7

102 02124841 Long Creek at Albemarle 33.1 1970–71, 1973–75 10 1 1.0 0.05j 0.7 0.3 0.2

104 02124869 Little Long Creek at SR 1903 

near Albemarle

29 1970–71, 1973–75 10 0 1.0 0.4 1.7 1.1 1.0

108 02124944 Little Bear Creek at Saint 

Martind 12.4 1961–62, 1970–71, 

1973, 1975

11 0 0.95 0 0.5 0.3 0.2

115 02125023 Big Bear Creek near Saint 

Martind 73.9 1949–54, 1961–62, 

1964, 1967–69, 

1975–77

63k 0 0.95 0.06 1.3 0.5 0.4

118 02125091 Stony Run tributary at SR 1975 

near Oakboro

1.6 1970–71, 1973–75 11 0 0.95 < 0.05 0.1 0.07 0.06

121 02125126 Long Creek near Oakboro 198 1970–71, 1973–77, 

1979–99, 2000, 

2002

88 0 0.95 2.6 14.1 9.6 8.4

123 02125139 Rocky River near Aquadaleb 973 1971, 1973 3 0 0.95 44.7 130.3 86.0 84.8

124 0212514705 Richardson Creek at SR 2139 

near Waxhaw

3.22 1974–77 19 0 0.9 0 < 0.05 < 0.05 < 0.05

132 02125223 Richardson Creek at SR 1751 

near Monroe

54.6 1970–73, 1975 13 0 0.9 0.3 0.7 0.5 0.5

139 02125310 Richardson Creek near Wingate 89 1953–54, 1956–59, 

1970–74, 1976–77

25 0 0.9 0.9 3.9 2.3 2.1

142 02125462 Meadow Branch at Wingate 4.62 1970–73, 1975 8 3 0.9 0l N/Al N/Al N/Al

144 02125464 Meadow Branch near Wingate 6.70 1970–73, 1975–77 16 1 0.9 0 0.1 0.06 < 0.05

145 02125482 Richardson Creek near Fairfield 153 1961-62, 1981-84, 

1986-99, 2000, 

2002

70 0 0.9 4.2m 8.7 6.8 6.4

147 02125538 6DOHP Creek at U.S.Highway 74

 near Marshville

1.44 1954, 1961, 1970-74 9 7 0.9 0n 0n 0n 0n

150 02125546 6DOHPCreek at SR 1002 

near Hamilton Crossroads

15.0 1953–54, 1957–58, 

1970–75

13 0 0.9 0 0.2 < 0.05 < 0.05

151 02125549 6DOHP Creek near Fairfield 23.6 1961–62, 1970–77 18 2 0.9 0 0.2 0.05 < 0.05

Table 6. Magnitude and frequency of annual low-flow characteristics at selected partial-record measuring sites in the Rocky River basin

in North Carolina — Continued

[USGS, U.S. Geological Survey; mi2, square miles; water year, the annual period from October 1 to September 30 and identified by the year in which the 

period ends; (ft3/s)/mi2, cubic feet per second per square mile; ft3/s, cubic feet per second; 7Q10, 7-day, 10-year low flow; 30Q2, 30-day, 2-year low flow; 

W7Q10, winter 7-day, 10-year low flow; 7Q2, 7-day, 2-year low flow; SR, secondary road; <, less than; N/A, not available; NPDES, National Pollutant 

Discharge Elimination System. Unless otherwise noted, low-flow characteristics typically reflect flow conditions unaffected by major diversions and(or) 

regulation] Site index no. (pl. 1)

USGS downstream 

order number

Station name

Drainage area

(mi2

)

Period of analysis

(water years)

Number of

measurements

Average annual unit 

flow [(ft3/s)/mi2

]

Low-flow characteristics

(ft3

/s)

Flow

Zero flow

7Q1030Q2

W7Q10

7Q2
Low-Flow Characteristics in the Rocky River Basin 23

154 02125591 Richardson Creek near 

Cottonville

234 1967, 1974–75, 

1981, 1982–84, 

2002

23o 0 0.9 0.8 6.6 3.9 3.2

161 02125720 Lanes Creek at Sturdivants 56.9 1961, 1964–69 13 0 0.9 0p 0.5 0.1 0.09

162 02125771 Beaverdam Creek near 

Marshville

14.9 1953, 1961-62, 1971 6 5 0.9 0n 0n 0n 0n

a

 Low-flow characteristics reflect NPDES discharges from the city of Mooreville wastewater-treatment plant, operated since 1981 on Dye Branch just 

upstream from its mouth where it empties into the Rocky River. Records of discharge prior to 1981 were not included in low-flow analyses for this site. b Low-flow characteristics for this site were not used in the low-flow discharge profiles presented in this report. The low-flow characteristics are based 

on records of discharge collected prior the late 1970’s and early 1980’s when NPDES discharges from three wastewater-treatment plants began (town of 

Mooresville, Charlotte-Mecklenburg Utilities, and Cabarrus County; see table 2). c

 Based on combined discharge records at partial-record measuring sites 02123953 (site 6), 02123989 (site 7), and 02123994 (site 8). Sixteen 

measurements were available in the combined record of discharges; discharges at sites 7 and 8 were adjusted by drainage area prior to analysis. d

 Low-flow characteristics previously published in Giese and Mason (1993); where different, estimates in this report supersede previous estimates. e

 Low-flow characteristics are based on combined discharge records at partial-record measuring sites 0212418255 (site 24) and 02124183 (site 25). 

Twelve measurements were available in the combined record of discharges; discharges at site 25 were adjusted by drainage area prior to analysis. f

This site is downstream from Lake Howell (formerly Coddle Creek Reservoir), which was completed in 1993. Records of discharge available for this 

site reflect flow conditions prior to completion of the lake. However, Coddle Creek was used as a source of water supply for Concord prior to the lake, and 

low-flow characteristics for this site reflect the effects of the water-supply diversions. At present, the effects of the Lake Howell on downstream low-flow 

characteristics cannot be assessed because no additional records of discharge have been collected at site 28 since the opening of the lake, which has a drainage area of approximately 47 mi2, or about 81 percent of the drainage area at site 28. g Low-flow characteristics reflect NPDES discharges from Cabarrus County wastewater-treatment plant, operated since 1979. Records of discharge 

prior to 1980 were not included in low-flow analyses for this site. h Low-flow characteristics for this site suggest the existence of a losing reach on Dutch Buffalo Creek (see other low-flow characteristics for sites 65, 

68, and 69). However, part of the reduction in low-flow yields between sites 65 and 69 may be a reflection of a water-supply withdrawal from Dutch Buffalo 

Creek by the town of Mount Pleasant. Estimate of 7Q10 discharge at site 73 could not be determined with reasonable level of certainty, but is likely in the 

range of 0.5 to 1.0 ft3

/s. i

 Estimate of 7Q10 discharge could not be determined with reasonable level of certainty.

j

 Site is just downstream from Long Lake west of Albemarle. The decrease in low-flow characteristics from partial-record measuring site 02124135 

(site 101) to this site apparently is affected by the lake. Low-flow characteristics for this site are presented as an example of the change in low-flow 

characteristics caused by an impoundment and should not be regarded as reflective of the entire drainage basin upstream from the site. k Based on combined discharge records at partial-record measuring sites 02125020 (site 114) and 02125023 (site 115). Sixty-three measurements were 

available in the combined record of discharges; discharges at site 114 were adjusted by drainage area prior to analysis. l

 Estimates for all low-flow characteristics cannot be determined based on available data; however, multiple observations of zero flow at site and(or) 

zero flow 7Q10 discharge at downstream site allow estimate of zero flow 7Q10 discharge at indicated site. m Low-flow characteristics for site location on Richardson Creek are relatively high (in terms of low-flow yields) compared to other locations on 

Richardson Creek (sites 124, 132, 139, and 154 in this table; site 146 in table 5). These characteristics reflect flow conditions since the opening of the watertreatment plant on Stewarts Creek just upstream from Richardson Creek in 1972 and the wastewater-treatment plant on Richardson Creek in 1965. n Due to multiple zero-flow discharge measurements at this site, low-flow characteristics are likely zero flow for the indicated statistic. o Based on combined discharge records at partial-record measuring sites 02125588 (site 153) and 02125591 (site 154). Twenty-three measurements 

were available in the combined record of discharges. Both sites have identical drainage areas (233 mi2

). Low-flow 

characteristics for this site suggest the existence of a losing reach on Richardson Creek (see other low-flow characteristics for site 145). p Low-flow characteristics for this site suggest the existence of a losing reach on Lanes Creek (see other low-flow characteristics for sites 157 and 165 

in table 5).

Table 6. Magnitude and frequency of annual low-flow characteristics at selected partial-record measuring sites in the Rocky River basin

in North Carolina — Continued

[USGS, U.S. Geological Survey; mi2, square miles; water year, the annual period from October 1 to September 30 and identified by the year in which the 

period ends; (ft3/s)/mi2, cubic feet per second per square mile; ft3/s, cubic feet per second; 7Q10, 7-day, 10-year low flow; 30Q2, 30-day, 2-year low flow; 

W7Q10, winter 7-day, 10-year low flow; 7Q2, 7-day, 2-year low flow; SR, secondary road; <, less than; N/A, not available; NPDES, National Pollutant 

Discharge Elimination System. Unless otherwise noted, low-flow characteristics typically reflect flow conditions unaffected by major diversions and(or) 

regulation] Site index no. (pl. 1)

USGS downstream 

order number

Station name

Drainage area

(mi2

)

Period of analysis

(water years)

Number of

measurements

Average annual unit 

flow [(ft3/s)/mi2

]

Low-flow characteristics

(ft3

/s)

Flow

Zero flow

7Q1030Q2

W7Q10

7Q2
24 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002

Figure 5. Correlation of concurrent discharge at the partial-record site at Clarke Creek near Harrisburg (site 12) and at the 

index station at Long Creek near Paw Creek (Catawba River basin).

reaches on several tributaries to the main stem. One 

such stream is Dutch Buffalo Creek (sites 65, 68, 69, 

and 73; tables 5 and 6), which is located primarily in 

northeastern Cabarrus County (pl. 1). Unit low-flow 

discharges at the three upstream sites (65, 68, and 69) 

are comparable. However, between sites 69 and 73, the 

unit low-flow discharges decrease by an average of 

about 37 percent (based on 30Q2, W7Q10, and 7Q2 

discharges; table 6). The basin drained by Dutch 

Buffalo Creek is mainly in the Charlotte Belt. However, 

it is possible that close proximity of the downstream 

reaches to the Carolina Slate Belt could result in the 

decreased unit low-flow discharges. The presence of a 

water-supply withdrawal from Dutch Buffalo Creek by 

the town of Mount Pleasant between sites 65 and 68 

was initially considered as a possible explanation for 

the decrease in unit low-flow discharges. However, the 

presence of comparable unit low-flow discharges at the 

three upstream sites (65, 68, and 69) indicates that such 

a decrease is apparently not the result of a diversion. 

Because the last discharge measurement at site 69 was 

made in 1975 as opposed to more current data (1980’s 

through 1990’s) collected at site 73, further explanation 

of this possible losing reach cannot be determined 

without additional data, including data at other 

locations between sites 69 and 73.

Other possible losing reaches were noted on 

Richardson Creek and Lanes Creek in Union and 

Anson Counties, respectively. These streams are 

located well within the Carolina Slate Belt geologic 

region and have a number of sites—some with 

drainage areas over 50 mi2—with zero-flow 7Q10 

discharges.

The possibility of a losing reach in Richardson 

Creek is recognized through the low-flow discharges at 

site 146 (table 5), which was operated for a brief period 

in the early 1940’s. The low-flow discharges for three 

upstream sites (132, 139, and 145; table 6) on 

Richardson Creek are based on periods of record that 

reflect streamflows affected by diversions in the 

vicinity of Monroe. However, a number of tributaries to 

Richardson Creek indicate zero 7Q10 discharges, 
Low-Flow Characteristics in the Rocky River Basin 25

which suggest the possibility of losing reaches in 

streams downstream from Stewart Creek (a tributary to 

Richardson Creek).

On Lanes Creek, the low-flow discharges at 

site 165 (table 5) identify this stream has having losing 

reaches, particularly in the upper part of the basin 

where a number of sites having zero 7Q10 discharges 

were noted (tables 5, 6). Insufficient data are available 

to assess low-flow discharges downstream from 

site 165; therefore, the possibility of a losing reach 

cannot be assessed.

A comparison was made of low-flow 

characteristics based on regional equations presented 

by Giese and Mason (1993) at five sites in HA9 in the 

Rocky River basin (table 7) with those based on 

analysis of streamflow data as previously outlined 

(tables 5 and 6). The five sites presented in table 7 were 

part of those used by Giese and Mason (1993) to 

develop the regional equations for estimating low-flow 

characteristics at ungaged sites. Percentage differences 

between the regional equation estimates and data 

estimates vary among the sites. Four of the five sites 

(12, 36, 37, and 65; table 7) have regional estimates that 

are higher than the data estimates, with percentage 

differences ranging from zero percent (7Q10 discharge 

at site 12) to 175 percent (winter 7Q10 at site 65). At 

site 34, the regional estimates are lower than the data 

estimates with percentage differences ranging from 

-42.3 percent (7Q10 discharge) to -9.1 percent (winter 

7Q10 discharge; table 7). For most sites, differences 

between the low-flow characteristics can be attributed 

to the general nature of residual errors associated with 

the use of a statistical regression to compute estimates. 

Still, the regional equations provided by Giese and 

Mason (1993) are useful for computing estimates at 

locations where no other data are available to assess 

low-flow characteristics. Given the standard errors 

identified for the HA9 regional equations (ranging 

from 49 to 92 percent; Giese and Mason, 1993), it is 

possible the data estimates (table 7) occur within the 

ranges specified by the standard errors.

Among the 44 partial-record measuring sites for 

which low-flow characteristics were compiled 

(table 6), the varying lengths of records along with the 

differing periods during which the measurements were 

obtained must be considered when assessing the 

reliability of the characteristics determined for each 

site. The length of record is expressed by the number of 

water years in which measurements were obtained for 

a given site. Among these 44 sites, the length of record 

ranged from 2 to 30 years (sites 123 and 121 with 3 and 

88 measurements, respectively) with a median equal to 

Table 7. Low-flow characteristics for selected partial-record measuring sites and regional equations in hydrologic area 9 (HA9) in the 

Rocky River basin in North Carolina 

[USGS, U.S. Geological Survey; mi2, square miles; water year, the annual period from October 1 to September 30 and identified by the year in which the 

period ends; ft3/s, cubic feet per second; 7Q10, 7-day, 10-year low flow; 30Q2, 30-day, 2-year low flow; W7Q10, winter 7-day, 10-year low flow; 7Q2, 7-day, 

2-year low flow; SR, secondary road; First line of low-flow characteristics (denoted Data under Method column) are those based on analysis of discharge 

records available for site and listed in table 7 (site type 1) or 8 (site type 2) depending on site type. The second line of low-flow characteristics are based on the 

regional equations (computed to two significant figures, denoted by hydrologic area under Method column) presented for HA9 in Giese and Mason (1993)] Site index no. (pl. 1) USGS downstream order number

Station name

Drainage area

(mi2

)

Period of

record

(water years)

Low-flow characteristics

(ft3

/s)

Site type

Method

7Q1030Q2

W7Q10

7Q2

12 02124080 Clarke Creek near Harrisburg 21.9 1951–71, 1988 1.0 3.0 2.3 2.1 2 Data

1.0 4.1 3.1 2.8 HA9

34 0212430295 Reedy Creek at SR 2804 near 

Wilgrove

12.7 1969–71, 1973, 1975 1.3 2.9 2.2 2.1 2 Data

0.75 2.6 2.0 1.8 HA9

36 0212430645 McKee Creek at SR 2808 near 

Wilgrove

4.08 1969–71, 1973, 1975 0.2 0.7 0.4 0.4 2 Data

0.41 1.0 0.82 0.76 HA9

37 02124320 Reedy Creek at Rocky River 30.9 1955–63, 2002 1.6 3.8 3.0 3.0 2 Data

1.2 5.4 4.1 3.7 HA9

65 02124460 Dutch Buffalo Creek near Rimer 33.8 1964–71, 1988 0.6 2.6 1.6 1.6 2 Data

1.3 5.9 4.4 3.9 HA9
26 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002

about 8 years. Previous discussion indicated that 10 or 

more measurements are generally needed to develop 

low-flow characteristics for a partial-record site. More 

importantly, such measurements should be sought 

during base-flow periods that are independent of each 

other (e.g., during the late summer and early fall of 

each year). Thus in the collection of discharge 

measurements at partial-record sites, a minimum of 2 

or 3 years of record are sought to improve the overall 

strength of the data available for analysis.

Measurements were obtained between 1948 and 

2002 with the highest numbers of sites measured in a 

given year occurring between 1961 and 1975. The 

years during which greater than 15 sites were measured 

were 1961–62, 1970–71, and 1973–75. At the gaging 

station near Norwood (site 169), the annual mean unit 

flow during these 7 years ranged from 0.58 to 

1.82 (ft3

/s)/mi2 (1970 and 1975, respectively) with an 

average of 1.14 (ft3/s)/mi2

. By comparison, the annual 

mean unit flow during the period of record (1930–

2001water years) ranged from 0.32 to 1.82 (ft3/s)/mi2

(2001 and 1975, respectively) with an average annual 

unit flow of 0.97 (ft3

/s)/mi2 for the period of record. 

Therefore, during 6 of the 7 years during which greater 

than 15 sites were measured, streamflow conditions at 

the gaging station near Norwood were normal or wetter 

than normal.

These considerations raise the possibility that 

some of the low-flow characteristics compiled for the 

partial-record sites (table 6) may be higher than true 

low-flow characteristics. However, in the absence of 

additional data collection at these and other sites, no 

means is available to re-assess the low-flow 

characteristics that would be regarded as more 

reflective of actual low-flow conditions. While steps 

can be taken to limit the inclusion of discharge 

measurements to those reflective of low-flow 

conditions, such steps would result in the removal of 

some sites from the overall analyses because of too few 

measurements and(or) would decrease the overall 

confidence in low-flow characteristics determined 

from a smaller number of measurements for a given 

site.

No ranges of statistical accuracy are provided for 

the low-flow characteristics presented in tables 5 and 6. 

While ranges of accuracy (e.g., 95-percent confidence 

intervals, standards errors) can be determined for 

results based on statistical techniques such as the 

MOVE.1 relation, the low-flow characteristics for 

many of the partial-record measuring sites and shortterm, continuous-record sites are based in part on 

correlation analyses using the graphical fit. The 

statistical accuracy of discharges determined from 

graphical correlations cannot be assessed. However, an 

alternate means of assessing the possible range in lowflow characteristics is to examine the unit low-flow 

discharges at nearby sites. Knowledge of the range in 

unit low-flow discharges can be used with the drainage 

area for an ungaged site to compute a range in the 

estimated low-flow discharges.

Occurrence of Zero or Minimal 7Q10 Discharges

Estimated 7Q10 discharges at 18 of the 56 sites 

(12 continuous-record and 44 partial-record, tables 5 

and 6) in the study area were determined to be zero, and 

one site had a 7Q10 discharge estimated to be less than 

0.05 ft3

/s. In previously published reports on the lowflow characteristics in the Roanoke River basin and the 

Deep River basin (tributary to the Cape Fear River), 

Weaver (1996, 1997) defined minimal 7Q10 discharges 

as those reported to be less than 0.1 ft3/s, a threshold 

used by Giese and Mason (1993) in reporting low-flow 

characteristics for streams across North Carolina. In the 

reports on low-flow characteristics in the Neuse River 

basin (Weaver, 1998) and Cape Fear River basin 

(Weaver and Pope, 2001), minimal 7Q10 discharges 

were re-defined to a lower threshold of 0.05 ft3/s, the 

minimum flow allowed by the DWQ in its evaluation of 

NPDES permits for point-source discharges. In this 

report, minimal 7Q10 discharges continue to be 

defined as those reported to be less than 0.05 ft3/s.

The 19 sites in the Rocky River basin having zero 

or minimal 7Q10 discharges were plotted on a map to 

determine which factors could account for the low 

potential to sustain base flow. Initial examination of the 

map indicated that 18 of the 19 sites were in the lower 

half of the basin downstream from the gaging station 

near Stanfield (site 85). Although common factors can 

be identified to explain the occurrence of zero or 

minimal 7Q10 discharges, all the factors that result in 

zero or minimal flows at one site may not be the same 

factors that cause zero or minimal flows at other sites. 

Thus, it is difficult to establish absolute thresholds of 

drainage areas at or below which 7Q10 discharges are 

assured of having zero or minimal flows. The 

determination of such drainage-area thresholds are 

subjective, requiring some interpretation and judgment. 

Although no drainage-area thresholds could be 

determined in the upper part of the basin (pl. 1), it does 
Low-Flow Discharge Profiles for the Rocky River 27

not mean that zero or minimal 7Q10 discharges do not 

occur on some streams in the area. Rather, only one 

occurrence of zero 7Q10 discharge in this area was 

identified from the data used in this analysis; thus, no 

drainage-area thresholds could be specified. Based on 

an assessment of 38 sites, Giese and Mason (1993) 

specified a drainage-area threshold of 1 mi2 for HA9, 

which covers much of the upper Rocky River basin 

(fig. 2; pl. 1).

The area of the Rocky River basin where 18 of 

the 19 occurrences of zero or minimal 7Q10 discharges 

were noted is underlain by the geologic rock units of 

the Carolina Slate Belt. Rocks in this area include 

metamorphosed mudstone, argillite, and graywacke, 

and metavolcanic flows and tuffs. All sites in the basin 

downstream from the gaging station near Stanfield 

(site 85) were arranged in ascending order by drainage 

area to determine if there was a maximum drainage 

area below which 7Q10 discharges generally are zero. 

Within this area, drainage areas for sites having zero or 

minimal 7Q10 discharges ranged from 1.44 (site 147) 

to 87.7 mi2

 (site 165). Of the 18 sites in this area, 15 

had drainage areas less than or equal to 23.6 mi2

(site 151), suggesting that ungaged sites in the Carolina 

Slate Belt having drainage areas less than about 25 mi2

likely will have zero or minimal 7Q10 discharges. 

Aside from site 165, other sites in the Carolina 

Slate Belt having larger drainage areas where zero or 

minimal 7Q10 discharges were noted are Big Bear 

Creek (site 113, drainage area 55.6 mi2

, tributary to 

Long Creek) and Lanes Creek (site 161, drainage area 

56.9 mi2). Well yields estimated by Daniel (1989) in 

this part of the study area were determined to be among 

the lowest for the hydrogeologic units in the Piedmont 

and Blue Ridge Provinces. Soils in this area typically 

are thin and have little water-storage capacity to sustain 

streams during base-flow periods (Charles Daniel, U.S. 

Geological Survey, oral commun., September 2000). 

The drainage-area threshold of 25 mi2 is higher than 

that identified by Giese and Mason (1993) for HA8 

(fig. 2), which covers most of the lower half of the 

Rocky River basin. Based on their investigation of nine 

sites in HA8 (argillite zone), they established a 

drainage-area threshold of 12 mi2

. The sites used in 

their investigation were not known to be affected by 

significant regulation and(or) diversions upstream from 

the sites (Giese and Mason, 1993).

LOW-FLOW DISCHARGE PROFILES FOR THE 

ROCKY RIVER

Discharge profiles of low flows were developed 

for the Rocky River to depict changes in low-flow 

discharges along most of its length. A drainage-area 

profile also was developed to document the relation 

between basin size and river miles. River miles shown 

on the profiles were determined by using the USEPA’s 

River Reach files, which are geographic information 

system (GIS) coverages of rivers and streams, digitized 

from 1:100,000-scale USGS topographic maps. River 

miles computed for the Rocky River begin at zero at the 

mouth and increase upstream.

The drainage-area profile for the Rocky River 

(fig. 6) reflects the shape of the entire river basin (pl. 1). 

Between the river’s initial reaches near Mooresville in 

Iredell County and Reedy Creek (tributary to the main 

stem) in Cabarrus County, the distance is about 31 mi, 

or about 33 percent of the river’s length. However, the 

accumulated drainage area in this reach is about 

234 mi2

, or about 17 percent of the total drainage area 

at the mouth of the Rocky River. In this reach between 

the headwaters and Reedy Creek, drainage-area 

contributions from tributary streams generally are less 

than 80 mi2 and include West Branch Rocky River 

(22.8 mi2), Clarke Creek (28.2 mi2), Mallard Creek 

(41.2 mi2

), Coddle Creek (78.8 mi2), and Reedy Creek 

(43.0 mi2

). In the reach between Reedy Creek and the 

mouth of the Rocky River, drainage-area increases are 

larger as a result of some of the major tributaries that 

drain to the Rocky River, which include Irish Buffalo/

Coldwater Creeks (110 mi2), Dutch Buffalo Creek 

(99 mi2), Long Creek (200 mi2

), Richardson Creek 

(234 mi2

), and Lanes Creek (135 mi2). Between the 

partial-record site near Oakboro (site 98, river 

mile 22.4, or about 25 percent of the river length) and 

the mouth of the Rocky River, the drainage area 

increases by 650 mi2, or 46 percent of the total 

drainage area. The Long Creek, Richardson Creek, and 

Lanes Creek tributaries drain to the Rocky River in this 

lowest reach.

Discharge profiles are presented for the 7Q10, 

30Q2, W7Q10, and 7Q2 discharges (figs. 7–10) for the 

segment of the Rocky River between a partial-record 

site near Davidson (site 3, river mile 85.8) and the longterm continuous-record gaging station near Norwood 

(site 169, river mile approximately 11.8). Low-flow 

characteristics at three continuous-record gaging 

stations (sites 40, 85, and 169; table 5) and two partialrecord sites (sites 3 and 60, table 6) on the Rocky River 
28 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002

Figure 6. Relation of river miles to drainage area for the Rocky River in North Carolina.

served as “anchor” points in the discharge profiles for 

estimating low-flow discharges at upstream and 

downstream locations. Low-flow discharges at the 

ungaged sites in the profile were estimated by using unit 

flows prorated on the basis of drainage areas for nearby 

upstream or downstream anchor points. Contributions 

of low flows from tributaries to the Rocky River were 

estimated when the drainage area from a tributary was 

5 percent or greater than the drainage area of the main 

stem directly upstream from the tributary, with the 

exception of Coddle Creek, as discussed below.

The low-flow characteristics for the sites used as 

anchor points in the profiles reflect flow conditions 

since the start of three major NPDES point-source 

discharges in the upper half of the basin in the late 

1970’s and early 1980’s (Dye Branch, Mallard Creek, 

and Rocky River discharge by Cabarrus County; 

table 2). Low-flow characteristics for seven partialrecord sites (6, 15, 24, 94, 97, 98, and 123; table 6) were 

not used in the profiles because discharge records 

available at these sites reflect streamflow conditions 

prior to start of the three major point-source discharges. 

During the investigation, attempts were made to 

develop profiles showing estimated low-flow 

discharges based on flow conditions not affected by the 

major NPDES point-source discharges. Records of 

discharge at the gaging stations above Irish Buffalo 

Creek (site 40) and near Stanfield (site 85) were 

adjusted to remove the effects of the major diversions; 

however, the variations in unit low-flow discharges at 

these sites precluded the development of reliable 

profiles for assessing the low-flow characteristics based 

on minor diversions.
Low-Flow Discharge Profiles for the Rocky River 29

Figure 7. Relation of river miles to annual 7-day, 10-year (7Q10) low-flow discharge for the Rocky River in North Carolina.

Low-flow discharge profiles for the Rocky River 

suggest different potentials for sustained base flow. 

Between sites 3 and 40, the 7Q10 discharge increases 

from 4.6 to 25.2 ft3/s (tables 5 and 6). Expressed in 

terms of the unit 7Q10 discharge (as cubic feet per 

second per square mile drainage area), this corresponds 

to a decrease from 0.34 to 0.09 (ft3/s)/mi2. At site 3, the 

unit 7Q10 discharge of 0.34 (ft3

/s)/mi2 reflects the 

point-source discharge on Dye Branch (table 2) and is 

not reflective of natural-flow characteristics. Previous 

low-flow investigations in North Carolina have shown 

that 7Q10 discharges having unit flows in the range of 

0.3 (ft3/s)/mi2 or higher typically occur in the Sand 

Hills region in the Coastal Plain (HA3, fig. 2) or in the 

higher elevations of the mountains region (HA10, 

fig. 2).

Downstream from site 40, the 7Q10 discharge 

increases to 42.3 and 45.8 ft3

/s at the gaging stations 

near Stanfield (site 85) and Norwood (site 169), 

respectively (table 5). Expressed as unit 7Q10 

discharges, this corresponds to a further decrease to 

about 0.07 and 0.03 (ft3/s)/mi2

, respectively, at these 

sites. The 30Q2, W7Q10, and 7Q2 discharges (as well 

as the corresponding unit low-flow discharges) 

exhibited similar trends between these sites (table 5).

Because low-flow discharges at locations 

between the anchor points are estimated by using the 

unit flows at these points along with estimates of 

tributary contributions, the development of discharge 

profiles for two particular reaches were identified as 

having a higher level of uncertainty than the other 

reaches (indicated by the dashed lines in figs. 7–10). 

The first reach is between Mallard Creek and Reedy 
30 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002

Figure 8. Relation of river miles to annual 30-day, 2-year (30Q2) low-flow discharge for the Rocky River in North Carolina.

Creek, and includes the area drained by Coddle Creek 

(fig. 7). The development of the profile is made difficult 

by the presence of the three major point-source 

discharges (table 2) on the Rocky River since the late 

1970’s. In addition, the effects of Lake Howell on lowflow characteristics in Coddle Creek downstream from 

the lake cannot be quantified because discharge records 

are unavailable for locations between the dam and the 

mouth of the stream since the opening of the lake in 

1993. Hence, the low-flow discharge profiles do not 

show any tributary contributions from Coddle Creek 

and are depicted with a dashed line to designate a reach 

where changes in low-flow characteristics are regarded 

as being more uncertain than other locations on the 

profiles. Despite the uncertainty associated with lowflow characteristics in the reach upstream and 

downstream from Coddle Creek, continual increases 

occur in the estimated low-flow discharges overall 

between Davidson and Stanfield, partly attributed to the 

three major point-source discharges.

The second reach where changes in low-flow 

profiles are considered uncertain is between gaging 

stations near Stanfield (site 85) and Norwood (site 169, 

fig. 7). Results of profile development indicate the 

presence of a possible losing reach, and support of this 

observation is available from three lines of evidence.

The first line of evidence is based on changes in 

the unit low-flow discharges. As previously stated, the 

7Q10 discharge increases from 42.3 to 45.8 ft3/s 

between the gaging stations near Stanfield and 

Norwood (sites 85 and 169, table 5). However, because 

the drainage area between these two sites increases 

from 628 to 1,372 mi2

, the unit 7Q10 discharge results 

in a 57-percent decrease (from 0.07 to 0.03 (ft3/s)/mi2

). 
Low-Flow Discharge Profiles for the Rocky River 31

Figure 9. Relation of river miles to winter 7-day, 10-year (W7Q10) low-flow discharge for the Rocky River in North Carolina.

Likewise, the 30Q2 discharge increases from 103 to 

113 ft3/s between the gaging stations (sites 85 and 169, 

table 5), representing a decrease in the unit 30Q2 

discharge from 0.16 to 0.08 (ft3

/s)/mi2, or a 50-percent 

decrease between the two sites. While decreasing unit 

flows alone are not indicators of a losing reach, the 

magnitude of the decrease in unit low flows between 

Stanfield and Norwood provides support in the 

identification of the losing reach. Upstream from 

Stanfield, most of the basin is underlain by the Charlotte 

Belt, the geologic unit within which streams have been 

observed to have moderate potential for sustained base 

flows. The transition from the Charlotte Belt is depicted 

as being rather sudden (North Carolina Geological 

Survey; 1985, 1991), meaning that much of the Rocky 

River basin between Stanfield and Norwood is 

underlain by the Carolina Slate Belt. Thus, the decrease 

in the unit low-flow discharges is primarily attributed to 

the underlying Carolina Slate Belt, a geologic unit 

within which streams have been observed as having 

little to no potential for sustained base flows.

The second line of evidence is based on the 

spatial distribution of sites having 7Q10 discharges less 

than minimal flow (defined as being 0.05 ft3

/s or less) 

or zero flow (tables 5 and 6). Of the 19 sites having 

7Q10 discharges less than minimal flow or zero flow, 18 

sites are on tributaries draining to the Rocky River in the 

reaches downstream from Stanfield, particularly in the 

basins drained by Long Creek, Richardson Creek, and 

Lanes Creek, which contribute a combined 40 percent 

of the total drainage area for the Rocky River. 

Compilations of the low-flow characteristics (tables 5 

and 6) indicated that losing reaches may exist in several 

tributaries to the Rocky River, including Richardson 
32 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002

Figure 10. Relation of river miles to annual 7-day, 2-year (7Q2) low-flow discharge for the Rocky River in North Carolina.

and Lanes Creeks (see discussion in preceding section 

Low-Flow Characteristics in the Rocky River Basin).

A third line of evidence to support a losing reach 

in the Rocky River downstream from Stanfield is found 

in the results of synoptic discharge measurements that 

were made at selected locations in the Rocky River 

basin during November 7–8, 2001 (fig. 11; table 8). 

On November 7, the range of discharges recorded at 

site 169 and the measured discharge at site 173 were 

lower than the measured discharge at the partial-record 

measuring site near Stanfield (site 94). Likewise on 

November 8, measurements made at two sites (85, 98) 

were lower than the discharge measured at a partialrecord site near Midland (site 75), indicating the losing 

reach may possibly extend upstream from Stanfield to 

Midland (fig. 11). In addition, while the discharge 

measured at the gaging station near Norwood (site 169) 

was higher in value, the unit flow of 0.06 (ft3

/s)/mi2

at this location was less than half of the unit flow of 

0.13 (ft3/s)/mi2 at the site near Midland (site 75, 

table 8).

Hydrographs of the discharges and stages at the 

three gaging stations (sites 40, 85, and 169) were 

checked to see if variations in measured flows could be 

accounted for by a wave of higher flow moving down 

the river during the 2-day period. No high flows were 

noted during the measurement period. The only 

variations noted in the hydrographs were daily 

fluctuations that apparently were reflective of the 

upstream point-source discharges. However, the 

magnitudes of the fluctuations did not account for the 

decreases in the measured discharges.

Given the three lines of evidence to support the 

possibility of a losing reach in the Rocky River, an 
Low-Flow Discharge Profiles for the Rocky River 33

Figure 11. Relation of river miles to synoptic discharge measurements made on November 7 – 8, 2001, at selected sites on the 

Rocky River, North Carolina.

assessment of the diversions in the lower half of the 

basin was necessary to determine if the losing reach 

might be the result of a major water-supply withdrawal. 

Downstream from Stanfield, no major water-supply 

withdrawals occur on the Rocky River. The only major 

withdrawal is made by the city of Monroe, which 

withdrew an average of 7.5 Mgal/d (11.6 ft3/s) in 

2001 (table 2) and returned a combined 7.5 Mgal/d 

(11.6 ft3/s) to Richardson Creek during the same period 

resulting in no overall change to flows in the stream. 

Another major diversion occurs in the form of a return 

point-source discharge to Long Creek by the city of 

Albemarle, which discharged an average of 9.6 Mgal/d 

(14.9 ft3

/s) in 2001 (table 2). This diversion, however, 

occurs upstream from the partial-record site near 

Bloomington (site 105; table 4) where the drainage area 

is approximately 66 mi2

 (the drainage area at the mouth 

of Long Creek is 200 mi2

). Given no other major 

diversions, particularly water-supply withdrawals, on 

the Rocky River downstream from Stanfield, the 

presence of a losing reach can be attributed to natural 

factors instead of human-induced effects to the river.

The estimated low-flow discharges depicted in 

the profiles for the reach between Stanfield and 

Norwood are shown by two dashed lines (figs. 7–10). 

The orange dashed line depicts the estimated 

discharges with tributary contributions from Long 

Creek, Richardson Creek, and Lanes Creek. Estimated 

contributions from Lanes Creek are zero flow for 7Q10 

discharge and minimal flows for the 30Q2, W7Q10, 

and 7Q2 discharges and, thus, are not visible on the 

profiles. The black dashed line depicts straight-line 

interpretation between the low-flow characteristics at 

Stanfield (site 85) and Norwood (site 169). Because of 

the uncertainty associated with the estimated low-flow 

discharges in this reach with tributary contributions, 

estimated discharges based on the black line may serve 

as the more reasonable estimates in the absence of 

additional data and(or) analyses that would further 

clarify the variations of low-flow characteristics in this 

reach.
34 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002 Table 8. Summary of synoptic discharge measurements obtained at selected sites in the Rocky River basin in North Carolina, Novem

[USGS, U.S. Geological Survey; mi2, square miles; ft3/s, cubic feet per second; (ft3/s)/mi2, cubic feet per second per square mile; SR, secondary road; N/A, not appl

tributary to the Rocky River]

Site index no.

(pl. 1)USGS down- stream order 

number

Station name Latitude Longitude

Drainage

area

(mi2

)

Discharge

(ft3/s)

Unit

discharge

[(ft3/s)/mi2

]

Time of measurement

(2400 hour time) 

November 7

3 02123881 Rocky River near Davidson 35° 28'29" 80° 46'48" 13.4 3.63 0.2709 10:00 – 10:30

7 02123989 Rocky River near Kannapolis 35° 26'31" 80° 45'08" 40.9 5.62 0.1374 11:47 – 12:22

13 02124091 Clarke Creek at Pleasant Grove 35° 23'12" 80° 43'46" 28.2 0.38 0.0135 13:27 – 13:4314 02124101 Rocky River near Pleasant Grove 35° 22'59" 80° 43'18" 76.8 6.72 0.0875 14:19 – 14:52

15 02124110 Rocky River near Roberta Mill 35° 21'33" 80° 40'31" 87.2 6.28 0.0720 15:52 – 16:22

23 02124160 Mallard Creek at Harrisburg 35° 20'02" 80° 40'05" 41.1 12.8 0.3114 17:04 – 17:3540 0212433550 Rocky River above Irish Buffalo 

Creek near Rocky River 

35° 19'22" 80° 32'17" 278 30 0.1079 N/A Estimated dail

discharge rec

84 0212471905 Goose Creek at SR 1547 near 

Faiview

35° 10'33" 80° 30'40" 41.4 0.6 0.0145 14:45 – 15:40

85 02124742 Rocky River near Stanfield 35° 10'10" 80° 28'24" 628 63 0.1003 N/A Estimated dail

discharge re

89 0212476710 Crooked Creek at SR 1547 near 

Fairview

35° 08'41" 80° 28'18" 47.3 3.06 0.0647 13:40 – 14:24

94 02124781 Rocky River at State Highway 

200 near Stanfield

35° 09'55" 80° 23'51" 708 84.7 0.1196 11:00 – 13:00

154 02125591 Richardson Creek near 

Cottonville

35° 09'27" 80° 14'07" 234 7.52 0.0321 15:41 – 16:20

169 02126000 Rocky River near Norwood 35° 08'54" 80° 10'33" 1,372 78 0.0569 N/A Estimated dail

discharge re

173 02126201 Rocky River at U.S. Highway 52 

near Norwood

35° 11'39" 80° 06'49" 1,403 79.7 0.0568 12:53 – 13:23
Low-Flow Discharge Profiles for the Rocky River 35

November 8

24 0212418255 Rocky River at SR 1304 near 

Harrisburg 

35° 20'06" 80° 37'41" 134a 18.5 0.1381 07:52 – 08:21

29 02124237 Coddle Creek near Harrisburg 35° 20'32" 80° 36'45" 74.3 5.89 0.0793 09:21 – 09:5833 02124277 Rocky River at Rocky River 35° 18'59" 80° 35'43" 231 27.9 0.1208 11:55 – 12:4537 02124320 Reedy Creek at Rocky River 35° 18'12" 80° 35'41" 30.9 2.21 0.0715 10:45 – 11:1740 0212433550 Rocky River above Irish Buffalo 

Creek near Rocky River 

35° 19'22" 80° 32'17" 278 30.3 0.1090 14:42 – 15:19

51 02124374 Irish Buffalo Creek near 

Faggarts Crossroads

35° 20'50" 80° 32'52" 45.5 5.15 0.1132 13:36 – 14:00 Irish Buffalo C

to the conflu

59 02124394 Coldwater Creek near Concord 35° 20'41" 80° 31'41" 63.4 2.2 0.0347 14:37 – 15:08 Irish Buffalo C

to the conflu

60 02124401 Rocky River near Flows Store 35° 19'26" 80° 30'59" 392 63.3 0.1615 13:58 – 16:00

73 02124596 Dutch Buffalo Creek at 

Georgeville

35° 18'51" 80° 27'52" 98.2 1.76 0.0179 16:50 – 17:40

75 02124644 Rocky River near Midland 35° 15'16" 80° 28'22" 536 71.3 0.1330 11:30 – 12:4577 02124668 Clear Creek at Brief 35° 11'40" 80° 31'46" 22.5 0.56 0.0249 08:45 – 10:30 Sum of two m

Clear Creek

85 02124742 Rocky River near Stanfield 35° 10'10" 80° 28'24" 628 62.5 0.0995 11:49 – 13:00

98 02124813 Rocky River near Oakboro 35° 11'42" 80° 16'48" 763 56.4 0.0739 10:28 – 11:03

121 02125126 Long Creek near Oakboro 35° 13'05" 80° 15'28" 198 13.8 0.0697 08:49 – 09:20145 02125482 Richardson Creek near 

Fairfield

35° 04'16" 80° 24'25" 153 8.9 0.0582 15:04 – 15:36

169 02126000 Rocky River near Norwood 35° 08'54" 80° 10'33" 1,372 77.5 0.0565 11:00 – 11:54

aApproximate drainage area.

Table 8. Summary of synoptic discharge measurements obtained at selected sites in the Rocky River basin in North Carolina, Novem[USGS, U.S. Geological Survey; mi2, square miles; ft3/s, cubic feet per second; (ft3/s)/mi2, cubic feet per second per square mile; SR, secondary road; N/A, not appl

tributary to the Rocky River]

Site index no.

(pl. 1)USGS down- stream order number Station name Latitude Longitude Drainage area (mi2) Discharge (ft3/s) Unit discharge [(ft3/s)/mi2] Time of measurement (2400 hour time) 
36 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002

The Rocky River exemplifies the difficulty in 

understanding and quantifying the factors that affect 

low-flow discharges. Topographic, geologic, and 

climatic factors usually can be understood more readily 

because, within a given region, the effects of these 

factors on low-flow discharges generally do not 

change, other than in areas of rapid development where 

topographic changes may occur in conjunction with 

land-use changes. Likewise, climate characteristics for 

a given area are fairly well understood with the 

availability of historic climatological records. 

However, human-induced flow modifications resulting 

from impoundments and flow diversions—

withdrawals and point-source discharges—and the 

absence of long-term streamflow records throughout 

the basin complicate the quantification of low-flow 

characteristics. In particular, the extent to which flow 

diversions affect low-flow characteristics can be 

difficult to quantify; in some instances, the presence of 

flow diversions upstream from a given location can 

only be acknowledged. Because of the complexity 

associated with the flow modifications as well as the 

losing reaches identified in the lower half of the basin, 

the opportunities for increased understanding of the 

low-flow characteristics in the Rocky River basin can 

best be achieved with the addition of streamflow 

monitoring sites, preferably for long-term periods.

SUMMARY

This report describes low-flow characteristics for 

the Rocky River basin in North Carolina. Low-flow 

characteristics were compiled for selected continuousrecord gaging stations and partial-record measuring 

sites in the study area, and drainage-area and low-flow 

discharge profiles were developed for the Rocky River. 

The low-flow characteristics and profiles in this report 

were developed in cooperation with the Water and 

Sewer Authority of Cabarrus County, CharlotteMecklenburg Utilities, and Union County.

In 1991, the North Carolina Department of 

Environment and Natural Resources began using a 

basinwide approach in its assessment of water-quality 

conditions in North Carolina; part of the assessment 

includes the simultaneous evaluation of National 

Pollution Discharge Elimination System (NPDES) 

permits for point-source discharges into streams in the 

basin. This report was prepared using the basinwide 

approach to compile low-flow characteristics for 

selected sites in the Rocky River basin and to develop 

drainage-area and low-flow discharge profiles for the 

Rocky River.

The Rocky River basin has a drainage area of 

1,413 mi2

 and merges with the Yadkin River in eastern 

Stanly County to form the Pee Dee River. Located in 

south-central North Carolina, the entire basin lies 

within the Piedmont Physiographic Province and is 

characterized by rolling and hilly topography. The 

Rocky River is nearly 91 mi long from the headwaters 

to the mouth of the river. The Rocky River begins near 

the town of Mooresville in Iredell County and flows 

southeast through Iredell and Cabarrus Counties, 

turning south in southeastern Cabarrus County, and 

then constitutes the county boundary between Stanly 

and Anson Counties and Stanly and Union Counties 

before draining into the Yadkin-Pee Dee River. Overall, 

land use in the Rocky River basin is rural; about 91 

percent of the basin is covered by forested and 

agricultural areas. Urban land uses occupy about 

7 percent of the basin.

Approximately 175 impoundments with dams 

having structural heights exceeding 15 ft were 

identified in the Rocky River basin. The vast majority 

of these impoundments have relatively small surface 

areas at the spillway level and are used primarily for 

sources of irrigation, sediment reduction, recreational 

activities, and(or) landscape features. Seven of these 

impoundments were identified as causing widespread 

inundation upstream from the dam. The largest 

impoundment is Lake Don T. Howell (formerly known 

as Coddle Creek Reservoir), which has a surface area of 

1,300 acres in Cabarrus County. This impoundment is 

the only one having a required minimum-flow release, 

which is 6.0 ft3/s. However, releases as low as 2.0 ft3/s 

were permitted to occur during the recent 1998–2002 

drought, and a tiered set of lower minimum-flow 

releases currently (2003) is being investigated for use 

during low-flow periods.

Withdrawals and return discharges were paired 

for 16 municipalities or other entities that use streams 

in the Rocky River as a source for withdrawals and(or) 

as the receiving stream for return point-source 

discharges. The largest withdrawals were made by the 

cities of Concord and Kannapolis, which withdrew an 

average of 9.8 and 6.1 Mgal/d, respectively, in 2001 

from Lake Howell and other smaller impoundments. 

The largest return point-source discharge in the basin is 

made by Cabarrus County, which treated and 

discharged an average of 16.3 Mgal/d in 2001 for 

Concord, Kannapolis, and several other smaller 
Summary 37

municipalities in Cabarrus County. Other substantial 

return discharges in the basin occur on Mallard Creek 

in Mecklenburg County and on Dye Branch in Iredell 

County near the town of Mooresville (6.0 and 

2.4 Mgal/d, respectively, in 2001). Aside from 

withdrawals made by Concord and Kannapolis, 

additional sources of water supply for other 

municipalities in the Rocky River basin are Mountain 

Island Lake (Charlotte-Mecklenburg) and Lake 

Norman (Mooresville) located west of the study area in 

the Catawba River basin, and Tuckertown and Narrows 

Reservoir (Albemarle) and Lake Tillery (Norwood) 

located east of the study area.

Soils and underlying hydrogeologic units in the 

Rocky River basin were examined to determine their 

effects on low flows. The Rocky River basin spans two 

of the major geologic belts in North Carolina—the 

Charlotte Belt in the upper half of the basin and the 

Carolina Slate Belt in much of the lower half. Streams 

in the Charlotte Belt are recognized as having moderate 

potential for sustained base flows, and streams in the 

Carolina Slate Belt are recognized as having little to no 

potential for sustained base flows, patterns that were 

observed in the compilations of low-flow 

characteristics at selected sites in the basin.

Twelve major soil series are present along the 

river’s course and directly adjacent to the Rocky River 

and its tributaries. The soils generally reflect the 

underlying geologic parent material with a mixture of 

soils derived from crystalline rock and soils derived 

from fine-grained Carolina Slate rock present 

throughout the basin. Loam is the dominant soil texture 

throughout the 12 soil series. Loam combination soil 

textures predominate in the basin, including sandy 

loam, silt loam, and clay loam, with silt loam most 

common. Two of the 12 series are clay soils. In general, 

all of the soils are considered to be moderately 

permeable (0.6 to 2 in. per hour). Streams in areas of 

clay soils have little or no source for sustained base 

flow during drought conditions.

The Rocky River basin includes 12 of 

18 hydrogeologic units identified for the Blue Ridge 

and Piedmont Provinces in North Carolina. Of these 

12 hydrogeologic units, 7 have average well yields 

below the mean average yield of 18.2 gal/min for 

hydrogeologic units in the Blue Ridge and Piedmont 

Provinces. When combined, these seven units make up 

nearly 64 percent of the Rocky River basin. The largest 

hydrogeologic unit in the basin is characterized by 

argillite rocks and covers nearly 48 percent of the basin, 

primarily in the lower half of the basin. This same unit 

has an average well yield of 14.6 gal/min, significantly 

below the average well yield for the Blue Ridge and 

Piedmont Provinces.

Records of surface-water data were identified 

and compiled for 173 sites in the study area. Low-flow 

characteristics (7Q10, 30Q2, W7Q10, and 7Q2) were 

determined for 56 sites (12 continuous-record and 

44 partial-record). Discharge records available at the 

continuous-record gaging stations through the 2002 

water year and at the partial-record measuring sites 

through the 2001 water year were used in the analyses 

of low-flow characteristics. At the continuous-record 

sites, the records were extended during the latter stages 

of the investigation to include discharges for the 2002 

water because of the 1998–2002 drought.

Of the 56 sites where low-flow characteristics 

were developed, 19 sites had minimal (defined as 

0.05 ft3/s or less) or zero 7Q10 discharges. The spatial 

distribution of these 19 sites was examined to 

determine if any drainage-area thresholds could be 

established for the basin. Eighteen of the 19 sites were 

present in the part of the basin underlain by the 

Carolina Slate Belt. Drainage areas among the 18 sites 

ranged from 1.44 to 87.7 mi2

 with 15 sites having 

drainage areas less than 23.6 mi2, suggesting that 7Q10 

discharges at ungaged sites in the Carolina Slate Belt 

with drainage areas less than about 25 mi2 likely will 

have zero or minimal discharges. Because only one site 

in the upper part of the basin (underlain by the 

Charlotte and Milton Belts) had a zero 7Q10 discharge, 

no drainage-area thresholds were established for this 

area.

Drainage-area and low-flow discharge profiles 

were developed for the Rocky River. The drainage-area 

profile shows increases in basin size for the entire reach 

of the Rocky River. Major tributaries draining to the 

Rocky River include Clarke Creek (28.2 mi2) and 

Mallard Creek (41.2 mi2

) in Mecklenburg and 

Cabarrus Counties; Coddle Creek (78.8 mi2) in Iredell, 

Rowan, and Cabarrus Counties; Irish Buffalo/

Coldwater Creek (110 mi2

) and Dutch Buffalo Creek 

(99 mi2) in Rowan and Cabarrus Counties; Long Creek 

(200 mi2

) in Stanly County; and Richardson Creek 

(234 mi2

) and Lanes Creek (135 mi2) in Union and 

Anson Counties.

The low-flow discharge profiles depict the 7Q10, 

30Q2, W7Q10, and 7Q2 discharges for the Rocky 
38 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002

River between a partial-record site near Davidson and 

a continuous-record gaging station near Norwood. Five 

sites on the Rocky River (two continuous-record and 

three partial-record sites) were used to estimate the 

low-flow discharges depicted in the profiles. The 

profiles indicate different potentials for sustained base 

flow between the upper and lower reaches of the main 

stem. In the upper reach between Davidson and 

Stanfield, flow profiles show continual increases in 

low-flow characteristics as a result of flow 

contributions from tributaries during base-flow 

conditions as well as several major point-source 

discharges. In the reach downstream from Stanfield, 

the profiles show a substantial decrease in the potential 

for sustained base flow as a result of little to no flow 

contributions from tributaries. Correspondingly, the 

profiles indicate the presence of a losing reach between 

Stanfield and Norwood. The presence of a losing reach 

is attributed to the soils and underlying rock types of 

the Carolina Slate Belt, which do not allow storage in 

surficial aquifers. Many streams in the lower parts of 

the basin have minimal (less than 0.05 ft3

/s) or zero 

7Q10 discharges.

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40 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002

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from Lake Michie, North Carolina 1961–71: U.S. 

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38–73, 27 p.

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selected South Carolina streams through 1987: U.S. 

Geological Survey Water-Resources Investigations 

Report 91–4170, 87 p.

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in National Water Summary 1988–89—Hydrologic 

events and floods and droughts: U.S. Geological Survey 

Water-Supply Paper 2375, p. 425–434.
Low-Flow Discharge Profiles for the Rocky River 41

Table 4. Summary of continuous-record gaging stations and partial-record measuring sites in the Rocky River basin in North Carolina where gag

collected

[mi2, square miles; SR, secondary road; N/A, not applicable; SEO, sewage effluent outfall. Period of record for continuous-record gaging stations (site type 1) is sho

for partial-record sites (site type 2) is shown in water years in which discharge measurements were made. Available records of discharge through the 2002 water yeastations and through the 2001 water year for partial-record measuring sites, except for selected partial-record sites where synoptic discharge measurements were collewater year). Shading indicates the continuous-record gaging stations (red) and partial-record sites (blue) for which low-flow characteristics have been developed]

Site index no. (pl. 1) USGS downstream order number Station name Latitude Longitude County USGS topographic quadrangle Drainage area (mi2) Tributary to Hydrologic unit code

Site type 

1 02123844 Dye Branch near Mooresville 35° 32'14" 80° 47'41" Iredell Mooresville 3.96 Rocky River 03040105 2 19

2 0212384510 Dye Branch at SR 1142 near 

Mooresville

35° 31'29" 80° 46'54" Iredell Mooresville 4.82 Rocky River 03040105 2 19

3 02123881 Rocky River near Davidson 35° 28'29" 80° 46'48" Mecklenburg Cornelius 13.4 Pee Dee River 03040105 2 194 02123917 West Branch Rocky River near 

Cornelius

35° 28'21" 80° 47'33" Mecklenburg Cornelius 13.6 Rocky River 03040105 2 19

5 02123932 South Prong West Branch Rocky 

River near Cornelius

35° 28'23" 80° 49'02" Mecklenburg Cornelius 4.98 West Branch 

Rocky River

03040105 2 19

6 02123953 Rocky River near Caldwell 35° 27'18" 80° 45'43" Cabarrus Cornelius 39.0 Pee Dee River 03040105 2 197 02123989 Rocky River near Kannapolis 35° 26'31" 80° 45'08" Cabarrus Cornelius 40.9 Pee Dee River 03040105 2 198 02123994 Rocky River at SR 1449 near 

Deweese

35° 25'27" 80° 44'28" Cabarrus Kannapolis 44.4 Pee Dee River 03040105 2 19

9 02124050 South Prong Clarke Creek near 

Huntersville

35° 24'21" 80° 48'06" Mecklenburg Cornelius 5.75 Clarke Creek 03040105 2 19

10 02124060 North Prong Clarke Creek near 

Huntersville

35° 25'11" 80° 47'53" Mecklenburg Cornelius 3.63 Clarke Creek 03040105 2 19

11 02124077 Ramah Creek near Huntersville 35° 25'26" 80° 45'56" Mecklenburg Cornelius 6.19 Clarke Creek 03040105 2 19

12 02124080 Clarke Creek near Harrisburg 35° 24'50" 80° 45'08" Cabarrus Cornelius 21.9 Rocky River 03040105 2 1913 02124091 Clarke Creek at Pleasant Grove 35° 23'12" 80° 43'46" Cabarrus Kannapolis 28.2 Rocky River 03040105 2 1914 02124101 Rocky River near Pleasant 

Grove

35° 22'59" 80° 43'18" Cabarrus Kannapolis 76.8 Pee Dee River 03040105 2 19

15 02124110 Rocky River near Roberta Mill 35° 21'33" 80° 40'31" Cabarrus Harrisburg 87.2 Pee Dee River 03040105 2 1916 02124122 Mallard Creek near Derita 35° 19'34" 80° 46'25" Mecklenburg Derita 11.9 Rocky River 03040105 2 1917 02124130 Mallard Creek near Charlotte 35° 19'05" 80° 44'14" Mecklenburg Harrisburg 20.6 Rocky River 03040105 2 1918 02124140 Toby Creek near Newell 35° 17'42" 80° 44'39" Mecklenburg Harrisburg 3.6a Mallard Creek 03040105 2 1919 02124146 Mallard Creek near Newell 35° 19'12" 80° 43'54" Mecklenburg Harrisburg 26.1 Rocky River 03040105 2 19
42 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002 20 0212414860 Stony Creek at U.S. Highway 29 near Harrisburg 35° 20'02" 80° 43'11" Mecklenburg Harrisburg 6.71 Mallard Creek 03040105 2 19

21 02124149 Mallard Creek below Stony Creek near Harrisburg 35° 19'57" 80° 42'58" Mecklenburg Harrisburg 34.6 Rocky River 03040105 1 De22 0212414950 Mallard Creek near Charlotte 35° 20'03" 80° 42'19" Mecklenburg Harisburg 36a Rocky River 03040105 2 1923 02124160 Mallard Creek at Harrisburg 35° 20'02" 80° 40'05" Cabarrus Harrisburg 41.1 Rocky River 03040105 2 1924 0212418255 Rocky River at SR 1304 near Harrisburg 35° 20'06" 80° 37'41" Cabarrus Harrisburg 134a Pee Dee River 03040105 2 1925 02124183 Rocky River at Harrisburg 35° 19'57" 80° 37'42" Cabarrus Harrisburg 136 Pee Dee River 03040105 2 1926 02124194 Coddle Creek near Deweeseb 35° 28'51" 80° 42'58" Cabarrus Kannapolis 32.2 Rocky River 03040105 2 1927 02124206 Coddle Creek at NC 73 near 

Concord

35° 26'12" 80° 41'52" Cabarrus Kannapolis 47.5 Rocky River 03040105 2 19

28 02124230 Coddle Creek near Concord 35° 24'29" 80° 40'29" Cabarrus Kannapolis 57.9 Rocky River 03040105 2 1929 02124237 Coddle Creek near Harrisburg 35° 20'32" 80° 36'45" Cabarrus Concord 74.3 Rocky River 03040105 2 1930 02124269 Back Creek above SEO near 

Harrisburg

35° 18'33" 80° 40'25" Cabarrus Harrisburg 7.45 Rocky River 02040105 2 19

31 02124270 Back Creek below SEO at 

Harrisburg

35° 18'48" 80° 39'10" Cabarrus Harrisburg 9a Rocky River 03040105 2 19

32 02124273 Back Creek near Harrisburg 35° 18'37" 80° 36'17" Cabarrus Concord SE 15.3 Rocky River 03040105 2 1933 02124277 Rocky River at Rocky River 35° 18'59" 80° 35'43" Cabarrus Concord SE 231 Pee Dee River 03040105 2 1934 0212430295 Reedy Creek at SR 2804 near 

Wilgrove

35° 15'32" 80° 39'46" Mecklenburg Harrisburg 12.7 Rocky River 03040105 2 19

35 02124303 Reedy Creek near Harrisburg 35° 16'48" 80° 38'46" Cabarrus Harrisburg 16.0 Rocky River 03040105 2 1936 0212430645 McKee Creek at SR 2808 near 

Wilgrove

35° 14'25" 80° 39'01" Mecklenburg Mint Hill 4.08 Reedy Creek 03040105 2 19

37 02124320 Reedy Creek at Rocky River 35° 18'12" 80° 35'41" Cabarrus Concord SE 30.9 Rocky River 03040105 2 1938 02124327 Caldwell Creek near Rocky 

River

35° 16'06" 80° 35'32" Cabarrus Concord SE 5.38 Reedy Creek 03040105 2 19

39 02124334 Rocky River near Rocky River 35° 19'27" 80° 33'40" Cabarrus Concord SE 277 Pee Dee River 03040105 2 19

Table 4. Summary of continuous-record gaging stations and partial-record measuring sites in the Rocky River basin in North Carolina where gag

collected — Continued

[mi2, square miles; SR, secondary road; N/A, not applicable; SEO, sewage effluent outfall. Period of record for continuous-record gaging stations (site type 1) is sho

for partial-record sites (site type 2) is shown in water years in which discharge measurements were made. Available records of discharge through the 2002 water yea

stations and through the 2001 water year for partial-record measuring sites, except for selected partial-record sites where synoptic discharge measurements were colle

water year). Shading indicates the continuous-record gaging stations (red) and partial-record sites (blue) for which low-flow characteristics have been developed]

Site index no. (pl. 1) USGS downstream order number Station name Latitude Longitude County USGS topographic quadrangle Drainage area (mi2

)

Tributary

to

Hydrologic

unit

code

Site type 
Low-Flow Discharge Profiles for the Rocky River 43

40 0212433550 Rocky River above Irish Buffalo 

Creek near Rocky River 

35° 19'22" 80° 32'17" Cabarrus Concord SE 278 Pee Dee River 03040105 1 Ap

41 02124337 Irish Buffalo Creek near Landis 35° 32'24" 80° 38'32" Rowan Enochville 5.24 Rocky River 03040105 2 1942 0212433839 Irish Buffalo Creek tributary at 

SR 1100 at Kannapolis

35° 30'37" 80° 37'58" Rowan Enochville 1.6a Irish Buffalo 

Creek

03040105 2 19

43 0212433840 Bleachers Creek at SR 1119 near 

Kannapolis

35° 30'26" 80° 38'09" Rowan Enochville 0.1a Boiler Room 

Branch

03040105 2 19

44 0212433843 Irish Buffalo Creek tributary at 

SR 1109 near Kannapolis

35° 30'34" 80° 38'48" Rowan Enochville 2.50 Irish Buffalo 

Creek

03040105 2 19

45 0212433845 Irish Buffalo Creek at SR 1124 

near Kannapolis

35° 30'30" 80° 38'53" Rowan Enochville 14.1 Rocky River 03040105 2 19

46 0212434059 Irish Buffalo Creek at SR 1609 

near Kannapolis

35° 29'16" 80° 39'13" Cabarrus Kannapolis 16a Rocky River 03040105 2 19

47 0212434410 Irish Buffalo Creek near Fisher 

Town

35° 28'23" 80° 39'19" Cabarrus Kannapolis 20.2 Rocky River 03040105 2 19

48 02124357 Irish Buffalo Creek at SR 1394 

near Concord

35° 24'52" 80° 36'46" Cabarrus Concord 32.3 Rocky River 03040105 2 19

49 02124366 Irish Buffalo Creek at NC 49 

near Concord

35° 22'15" 80° 33'50" Cabarrus Concord SE 40.9 Rocky River 03040105 2 19

50 02124368 Irish Buffalo Creek near 

Concord

35° 21'49" 80° 33'25" Cabarrus Concord SE 42.2 Rocky River 03040105 2 19

51 02124374 Irish Buffalo Creek near 

Faggarts Crossroads

35° 20'50" 80° 32'52" Cabarrus Concord SE 45.5 Rocky River 03040105 2 19

52 0212437525 Coldwater Creek tributary near 

China Grove

35° 33'15" 80° 35'00" Rowan China Grove 0.2a Coldwater 

Creek

03040105 2 19

53 02124377 Coldwater Creek near Landis 35° 31'36" 80° 34'27" Rowan China Grove 7.66 Rocky River 03040105 2 1954 02124379 Coldwater Creek tributary at 

Kannapolis

35° 30'58" 80° 34'35" Rowan China Grove 3.99 Coldwater 

Creek

03040105 2 19

55 02124382 Threemile Branch at Kannapolis 35° 27'14" 80° 36'33" Cabarrus Concord 1.76 Coldwater 

Creek

03040105 2 19

56 02124383 Threemile Branch near 

Kannapolis

35° 26'26" 80° 35'30" Cabarrus Concord 2.84 Coldwater 

Creek

03040105 2 19

Table 4. Summary of continuous-record gaging stations and partial-record measuring sites in the Rocky River basin in North Carolina where gag

collected — Continued

[mi2, square miles; SR, secondary road; N/A, not applicable; SEO, sewage effluent outfall. Period of record for continuous-record gaging stations (site type 1) is sho

for partial-record sites (site type 2) is shown in water years in which discharge measurements were made. Available records of discharge through the 2002 water yeastations and through the 2001 water year for partial-record measuring sites, except for selected partial-record sites where synoptic discharge measurements were collewater year). Shading indicates the continuous-record gaging stations (red) and partial-record sites (blue) for which low-flow characteristics have been developed]

Site index no. (pl. 1) USGS downstream order number Station name Latitude Longitude County USGS topographic quadrangle Drainage area (mi2

)

Tributary

to

Hydrologic

unit

code

Site type 
44 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002 57 02124388 Threemile Branch at Concord 35° 24'37" 80° 34'04" Cabarrus Concord 5.30 Coldwater Creek 03040105 2 19

58 02124391 Little Coldwater Creek near 

Concord

35° 23'26" 80° 32'15" Cabarrus Concord 13.5 Coldwater 

Creek

03040105 2 19

59 02124394 Coldwater Creek near Concord 35° 20'41" 80° 31'41" Cabarrus Concord SE 63.4 Irish Buffalo 

Creek

03040105 2 19

60 02124401 Rocky River near Flows Store 35° 19'26" 80° 30'59" Cabarrus Concord SE 392 Pee Dee River 03040105 2 19

2

61 02124408 Hamby Branch near Georgeville 35° 19'29" 80° 30'13" Cabarrus Concord SE 6.94 Rocky River 03040105 2 1962 02124420 Rocky River near Concord 35° 18'50" 80° 28'45" Cabarrus Mount Pleasant 402a Pee Dee River 03040105 2 1963 02124448 Little Buffalo Creek at NC 49 

near Mount Pleasant

35° 26'02" 80° 23'56" Cabarrus Mount Pleasant 15.6 Dutch Buffalo 

Creek

03040105 2 19

64 02124458 Dutch Buffalo Creek near Watts 

Crossroads

35° 26'30" 80° 27'20" Cabarrus Mount Pleasant 24.5 Rocky River 03040105 2 19

65 02124460 Dutch Buffalo Creek near Rimer 35° 26'30" 80° 26'38" Cabarrus Mount Pleasant 33.8 Rocky River 03040105 2 1966 02124468 Black Run Creek near Watts 

Crossroads

35° 26'23" 80° 26'18" Cabarrus Mount Pleasant 6.71 Dutch Buffalo 

Creek

03040105 2 19

67 0212446990 Dutch Buffalo Creek above NC 

49 near Mount Pleasant

35° 25'59" 80° 25'11" Cabarrus Mount Pleasant 43a Rocky River 03040105 2 19

68 02124471 Dutch Buffalo Creek at NC 49 

near Mount Pleasant

35° 25'37" 80° 24'40" Cabarrus Mount Pleasant 45.1 Rocky River 03040105 1 M

69 02124500 Dutch Buffalo Creek at Mount 

Pleasant

35° 23'45" 80° 25'00" Cabarrus Mount Pleasant 65.4 Rocky River 03040105 2 19

70 02124524 Dutch Buffalo Creek near Mount 

Pleasant

35° 23'20" 80° 25'28" Cabarrus Mount Pleasant 66.2 Rocky River 03040105 2 19

71 02124548 Adams Creek at Mount Pleasant 35° 23'13" 80° 26'17" Cabarrus Mount Pleasant 15.6 Dutch Buffalo 

Creek

03040105 2 19

72 02124572 Dutch Buffalo Creek near 

Barriers Mill

35° 20'17" 80° 26'46" Cabarrus Mount Pleasant 94.4 Rocky River 03040105 2 19

73 02124596 Dutch Buffalo Creek at 

Georgeville

35° 18'51" 80° 27'52" Cabarrus Locust 98.2 Rocky River 03040105 2 19

6

74 02124621 Anderson Creek near Cabarrus 35° 16'00" 80° 30'08" Cabarrus Concord SE 11.4 Rocky River 03040105 2 19

Table 4. Summary of continuous-record gaging stations and partial-record measuring sites in the Rocky River basin in North Carolina where gag

collected — Continued

[mi2, square miles; SR, secondary road; N/A, not applicable; SEO, sewage effluent outfall. Period of record for continuous-record gaging stations (site type 1) is sho

for partial-record sites (site type 2) is shown in water years in which discharge measurements were made. Available records of discharge through the 2002 water yea

stations and through the 2001 water year for partial-record measuring sites, except for selected partial-record sites where synoptic discharge measurements were colle

water year). Shading indicates the continuous-record gaging stations (red) and partial-record sites (blue) for which low-flow characteristics have been developed]

Site index no. (pl. 1) USGS downstream order number Station name Latitude Longitude County USGS topographic quadrangle Drainage area (mi2

)

Tributary

to

Hydrologic

unit

code

Site type 
Low-Flow Discharge Profiles for the Rocky River 45

75 02124644 Rocky River near Midland 35° 15'16" 80° 28'22" Cabarrus Mount Pleasant 536 Pee Dee River 03040105 2 1976 02124660 Clear Creek at SR 3181 near 

Mint Hill

35° 12'29" 80° 34'48" Mecklenburg Midland 12.6 Rocky River 03040105 2 19

77 02124668 Clear Creek at Brief 35° 11'40" 80° 31'46" Union Midland 22.5 Rocky River 03040105 2 1978 0212466825 Clear Creek Tributary at Brief 35° 11'38" 80° 31'29" Union Midland 0.82 Clear Creek 03040105 2 2079 02124675 Goose Creek at SR 1524 near 

Mint Hill

35° 07'48" 80° 37'51" Union Midland 8.6a Rocky River 03040105 2 19

80 02124692 Goose Creek at Fairview 35° 09'14" 80° 32'09" Union Midland 24.0 Rocky River 03040105 1 No

2 19

81 0212471765 Duck Creek tributary at NC 218 

near Brief

35° 09'50" 80° 35'13" Union Midland 2.80 Yadkin River 03040105 2 19

82 0212471785 Duck Creek tributary at NC 218 

near Fairview

35° 09'45" 80° 34'26" Union Midland 0.81 Yadkin River 03040105 2 19

83 02124718 Duck Creek at Brief 35° 10'52" 80° 32'28" Union Midland 12.1 Goose Creek 03040105 2 1984 0212471905 Goose Creek at SR 1547 near 

Faiview

35° 10'33" 80° 30'40" Union Midland 41.4 Rocky River 03040105 2 20

85 02124742 Rocky River near Stanfield 35° 10'10" 80° 28'24" Stanly Stanfield 628 Pee Dee River 03040105 1 Ap

2 19

86 02124745 North Fork Crooked Creek near 

Fairview

35° 06'32" 80° 33'43" Union Bakers 16a Crooked Creek 03040105 2 19

87 02124761 South Fork Crooked Creek near 

Unionville

35° 06'26" 80° 32'56" Union Bakers 18.4 Crooked Creek 03040105 2 19

88 02124766 Crooked Creek at Fairview 35° 07'44" 80° 32'14" Union Midland 36.9 Rocky River 03040105 2 1989 0212476710 Crooked Creek at SR 1547 near 

Fairview

35° 08'41" 80° 28'18" Union Stanfield 47.3 Rocky River 03040105 2 20

90 02124772 Grassy Creek near Fairview 35° 07'53" 80° 26'34" Union Stanfield 4.50 Rocky River 03040105 2 1991 02124773 Rock Hole Creek at SR 1147 

near Stanfield

35° 12'58" 80° 26'34" Stanly Stanfield 4.27 Rocky River 03040105 2 19

92 02124776 Rock Hole Creek at Stanfield 35° 12'14" 80° 25'58" Stanly Stanfield 7.55 Rocky River 03040105 2 1993 02124778 Rock Hole Creek near Stanfield 35° 10'39" 80° 24'37" Stanly Stanfield 11.7 Rocky River 03040105 2 19

Table 4. Summary of continuous-record gaging stations and partial-record measuring sites in the Rocky River basin in North Carolina where gag

collected — Continued

[mi2, square miles; SR, secondary road; N/A, not applicable; SEO, sewage effluent outfall. Period of record for continuous-record gaging stations (site type 1) is sho

for partial-record sites (site type 2) is shown in water years in which discharge measurements were made. Available records of discharge through the 2002 water yeastations and through the 2001 water year for partial-record measuring sites, except for selected partial-record sites where synoptic discharge measurements were collewater year). Shading indicates the continuous-record gaging stations (red) and partial-record sites (blue) for which low-flow characteristics have been developed]

Site index no. (pl. 1) USGS downstream order number Station name Latitude Longitude County USGS topographic quadrangle Drainage area (mi2) Tributary to Hydrologic unit code

Site type 
46 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002 94 02124781 Rocky River at State Highway 200 near Stanfield 35° 09'55" 80° 23'51" Stanly Stanfield 708 Pee Dee River 03040105 2 19

95 02124789 Island Creek near Locust 35° 15'38" 80° 24'06" Stanly Mount Pleasant 3.10 Rocky River 03040105 2 1996 02124794 Island Creek near Stanfield 35° 11'51" 80° 22'28" Stanly Oakboro 19.2 Rocky River 03040105 2 1997 02124798 Rocky River at State Highway 205 near Oakboro 35° 10'09" 80° 20'44" Stanly Oakboro 744 Pee Dee River 03040105 2 1998 02124813 Rocky River near Oakboro 35° 11'42" 80° 16'48" Stanly Oakboro 763 Pee Dee River 03040105 2 1999 02124823 Long Creek at SR 1454 near Richfield 35° 28'21" 80° 17'37" Stanly Mount Pleasant 5.29 Rocky River 03040105 2 19

100 02124827 Long Creek near Richfield 35° 26'24" 80° 16'28" Stanly Mount Pleasant 12.6 Rocky River 03040105 2 19101 02124835 Long Creek near Plyler 35° 22'51" 80° 14'48" Stanly New London 27.5 Rocky River 03040105 2 19102 02124841 Long Creek at Albemarle 35° 19'55" 80° 12'45" Stanly Albemarle 33.1 Rocky River 03040105 2 19103 02124861 Little Long Creek at Albemarle 35° 21'39" 80° 12'15" Stanly Albemarle 20.5 Long Creek 03040105 2 19

6

104 02124869 Little Long Creek at NC 24/27 

near Albemarle

35° 20'13" 80° 12'38" Stanly Albemarle 29a Long Creek 03040105 2 19

105 0212488455 Long Creek near Bloomington 35° 18'25" 80° 13'48" Stanly Albemarle 66a Rocky River 03040105 2 19106 02124908 Long Creek near Hills 35° 16'57" 80° 14'52" Stanly Albemarle 72.4 Rocky River 03040105 2 19107 02124941 Little Bear Creek near Hills 35° 18'20" 80° 16'25" Stanly Mount Pleasant 6.99 Long Creek 03040105 2 19108 02124944 Little Bear Creek at Saint Martin 35° 16'02" 80° 16'04" Stanly Mount Pleasant 12.4 Long Creek 03040105 2 19109 02124948 Long Creek tributary near Saint 

Martin

35° 15'00" 80° 15'00" Stanly Oakboro 10.6 Long Creek 03040105 2 19

110 02124958 Big Bear Creek near Finger 35° 21'56" 80° 20'55" Stanly Mount Pleasant 20.3 Long Creek 03040105 2 19111 02124981 Little Bear Creek near Finger 35° 23'05" 80° 22'18" Stanly Mount Pleasant 10.9 Big Bear Creek 03040105 2 19112 02124998 Little Creek near Bloomington 35° 20'10" 80° 20'10" Stanly Mount Pleasant 7.10 Big Bear Creek 03040105 2 19113 02125000 Big Bear Creek near Richfield 35° 20'02" 80° 20'09" Stanly Frog Pond 55.6 Rocky River 03040105 1 M114 02125020 Big Bear Creek near Albemarle 35° 16'49" 80° 18'10" Stanly Frog Pond 70.5 Long Creek 03040105 2 19

Table 4. Summary of continuous-record gaging stations and partial-record measuring sites in the Rocky River basin in North Carolina where gag

collected — Continued

[mi2, square miles; SR, secondary road; N/A, not applicable; SEO, sewage effluent outfall. Period of record for continuous-record gaging stations (site type 1) is sho

for partial-record sites (site type 2) is shown in water years in which discharge measurements were made. Available records of discharge through the 2002 water yea

stations and through the 2001 water year for partial-record measuring sites, except for selected partial-record sites where synoptic discharge measurements were colle

water year). Shading indicates the continuous-record gaging stations (red) and partial-record sites (blue) for which low-flow characteristics have been developed]

Site index no. (pl. 1) USGS downstream order number Station name Latitude Longitude County USGS topographic quadrangle Drainage area (mi2

)

Tributary

to

Hydrologic

unit

code

Site type 
Low-Flow Discharge Profiles for the Rocky River 47

115 02125023 Big Bear Creek near Saint 

Martin

35° 15'23" 80° 17'15" Stanly Frog Pond 73.9 Long Creek 03040105 2 19

116 02125052 Stony Run at Red Cross 35° 17'06" 80° 20'53" Stanly Mount Pleasant 8.28 Big Bear Creek 03040105 2 19117 02125084 Stony Run near Red Cross 35° 16'21" 80° 19'27" Stanly Mount Pleasant 10.2 Big Bear Creek 03040105 2 19118 02125091 Stony Run tributary at SR 1975 

near Oakboro

35° 14'54" 80° 18'45" Stanly Oakboro 1.6a Stony Run 03040105 2 19

119 02125116 Stony Run near Saint Martin 35° 14'53" 80° 17'34" Stanly Oakboro 19.7 Big Bear Creek 03040105 2 19120 02125122 Big Bear Creek near Aquadale 35° 15'18" 80° 16'27" Stanly Oakboro 95.5 Long Creek 03040105 2 19121 02125126 Long Creek near Oakboro 35° 13'05" 80° 15'28" Stanly Oakboro 198 Rocky River 03040105 2 19122 02125132 Long Creek tributary No. 2 near 

Aquadale

35° 13'00" 80° 15'00" Stanly Oakboro 2.0a Long Creek 03040105 2 19

123 02125139 Rocky River near Aquadale 35° 10'19" 80° 14'16" Stanly Aquadale 973 Pee Dee River 03040105 2 19124 0212514705 Richardson Creek at SR 2139 

near Waxhaw

34° 54'40" 80° 35'38" Union Monroe 3.22 Rocky River 03040105 2 19

125 02125148 Richardson Creek at NC 207 

near Monroe

34° 57'14" 80° 32'42" Union Monroe 32.6 Rocky River 03040105 2 19

126 02125181 Richardson Creek at Monroe 34° 57'37" 80° 31'23" Union Monroe 34a Rocky River 03040105 2 19127 02125183 Richardson Creek above water 

intake near Monroe

34° 57'50" 80° 30'49" Union Monroe 50a Rocky River 03040105 2 19

128 02125199 Little Richardson Creek near 

Altan

34° 55'30" 80° 31'11" Union Monroe 7.01 Richardson 

Creek

03040105 2 19

129 02125201 Little Richardson Creek 

tributary No.2 near Altan

34° 56'00" 80° 31'00" Union Monroe 0.9a Little Richardson Creek 03040105 2 19

130 02125204 Little Richardson Creek 

tributary near Monroe

34° 56'02" 80° 30'26" Union Monroe 3.26 Richardson 

Creek

03040105 2 19

131 02125212 Richardson Creek near Monroe 34° 58'26" 80° 30'37" Union Monroe 52.2 Rocky River 03040105 2 19132 02125223 Richardson Creek at SR 1751 

near Monroe

34° 59'24" 80° 30'36" Union Monroe 54.6 Rocky River 03040105 2 19

133 0212522625 Bearskin Creek at SR 1007 near 

Bakers

35° 00'10" 80° 36'34" Union Bakers 1.9a Richardson 

Creek

03040105 2 19

Table 4. Summary of continuous-record gaging stations and partial-record measuring sites in the Rocky River basin in North Carolina where gag

collected — Continued

[mi2, square miles; SR, secondary road; N/A, not applicable; SEO, sewage effluent outfall. Period of record for continuous-record gaging stations (site type 1) is sho

for partial-record sites (site type 2) is shown in water years in which discharge measurements were made. Available records of discharge through the 2002 water yeastations and through the 2001 water year for partial-record measuring sites, except for selected partial-record sites where synoptic discharge measurements were collewater year). Shading indicates the continuous-record gaging stations (red) and partial-record sites (blue) for which low-flow characteristics have been developed]

Site index no. (pl. 1) USGS downstream order number Station name Latitude Longitude County USGS topographic quadrangle Drainage area (mi2

)

Tributary

to

Hydrologic

unit

code

Site type 
48 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002 134 02125228 Bearskin Creek near Bakers 34° 59'00" 80° 34'00" Union Monroe 16a Richardson Creek 03040105 2 19

135 0212523050 Bearskin Creek at Hayne Street at Monroe 34° 59'24" 80° 32'57" Union Monroe 19a Richardson Creek 03040105 2 19136 02125244 Bearskin Creek at Monroe 34° 59'46" 80° 31'24" Union Monroe 14.3 Richardson Creek 03040105 2 19137 02125246 Bearskin Creek near Monroe 34° 59'24" 80° 30'37" Union Monroe 15.0 Richardson Creek 03040105 2 19138 02125276 Flag Branch near Wingate 34° 59'00" 80° 28'00" Union Wingate 12.8 Richardson Creek 03040105 2 19139 02125310 Richardson Creek near Wingate 35° 01'58" 80° 28'20" Union Watson 89a Rocky River 03040105 2 19140 02125410 Chinkapin Creek near Monroe 35° 02'48" 80° 29'33" Union Watson 8.5a Richardson Creek 03040105 2 19141 02125456 Stewarts Creek near Monroe 35° 02'15" 80° 28'34" Union Watson 35.4 Richardson Creek 03040105 2 19

7

142 02125462 Meadow Branch at Wingate 35° 00'20" 80° 26'51" Union Watson 4.62 Richardson Creek 03040105 2 19143 0212546245 Meadow Branch tributary at SR 1631 near Wingate 35° 00'44" 80° 26'29" Union Watson 0.3a Meadow Branch 03040105 2 19144 02125464 Meadow Branch near Wingate 35° 01'53" 80° 27'07" Union Watson 6.70 Richardson Creek 03040105 2 19145 02125482 Richardson Creek near Fairfield 35° 04'16" 80° 24'25" Union Watson 153 Rocky River 03040105 2 19146 02125500 Richardson Creek near Marshville 35° 05'53" 80° 23'03" Union Watson 163 Rocky River 03040105 1 Ap147 02125538 6DOHPCreek at U.S. Highway 74 near Marshville 34° 59'05" 80° 24'05" Union Wingate 1.44 Richardson Creek 03040105 2 19148 0212553855 6DOHPCreek at SR 1751 

near Marshville

34° 59'44" 80° 23'29" Union Wingate 3.25 Richardson 

Creek

03040105 2 19

149 02125543 6DOHP Creek at NC 205 

near Marshville

35° 00'46" 80° 22'39" Union Watson 7.68 Richardson 

Creek

03040105 2 19

Table 4. Summary of continuous-record gaging stations and partial-record measuring sites in the Rocky River basin in North Carolina where gag

collected — Continued

[mi2, square miles; SR, secondary road; N/A, not applicable; SEO, sewage effluent outfall. Period of record for continuous-record gaging stations (site type 1) is sho

for partial-record sites (site type 2) is shown in water years in which discharge measurements were made. Available records of discharge through the 2002 water yea

stations and through the 2001 water year for partial-record measuring sites, except for selected partial-record sites where synoptic discharge measurements were colle

water year). Shading indicates the continuous-record gaging stations (red) and partial-record sites (blue) for which low-flow characteristics have been developed]

Site index no. (pl. 1) USGS downstream order number Station name Latitude Longitude County USGS topographic quadrangle Drainage area (mi2

)

Tributary

to

Hydrologic

unit

code

Site type 
Low-Flow Discharge Profiles for the Rocky River 49

150 02125546 6DOHP Creek at SR 1002 

near Hamilton Crossroads

35° 02'37" 80° 21'56" Union Olive Branch 15.0 Richardson 

Creek

03040105 2 19

151 02125549 Salem Creek near Fairfield 35° 04'30" 80° 22'07" Union Olive Branch 23.6 Richardson 

Creek

03040105 2 19

152 02125557 Gourdvine Creek near Olive 

Branch

35° 06'02" 80° 20'11" Union Olive Branch 8.75 Richardson 

Creek

03040105 1 Ju

2 19

153 02125588 Richardson Creek near Kikers 35° 09'11" 80° 14'50" Anson Aquadale 233 Rocky River 03040105 2 19154 02125591 Richardson Creek near 

Cottonville

35° 09'27" 80° 14'07" Anson Aquadale 234 Rocky River 03040105 2 19

155 02125636 Cribs Creek near Burnsville 35° 07'55" 80° 12'17" Anson Aquadale 14.0 Rocky River 03040105 2 19156 02125650 Rocky River at SR 1943 near 

Aquadale

35° 09'52" 80° 12'22" Stanly Aquadale 1,232 Peedee River 03040105 2 20

157 02125696 Lanes Creek near Trinity 34° 50'39" 80° 28'49" Union Pageland, 

SC-NC

4.92 Rocky River 03040105 1 Ju

158 02125698 Lanes Creek near Monroe 34° 50'42" 80° 26'02" Union Pageland, 

SC-NC

12.7 Rocky River 03040105 2 19

159 02125699 Wicker Branch near Trinity 34° 52'54" 80° 26'24" Union Wingate 5.83 Lanes Creek 03040105 1 Ju160 02125712 Lanes Creek near Sturdivants 34° 53'53" 80° 23'03" Union Wingate 43.9 Rocky River 03040105 2 19161 02125720 Lanes Creek at Sturdivants 34° 55'26" 80° 20'32" Union Marshville 56.9 Rocky River 03040105 2 19162 02125771 Beaverdam Creek near 

Marshville

34° 57'14" 80° 21'07" Union Marshville 14.9 Lanes Creek 03040105 2 19

163 02125812 Lanes Creek at SR 1900 near 

Marshville

34° 58'08" 80° 18'44" Union Marshville 81a Rocky River 03040105 2 19

164 02125813 Lick Branch below SEO near 

Marshville

34° 58'52" 80° 19'53" Union Marshville 3.03 Lanes Creek 03040105 2 19

165 02125816 Lanes Creek near Marshville 34° 58'31" 80° 18'14" Union Marshville 87.7 Rocky River 03040105 1 M

2 19

166 02125861 Lanes Creek tributary near 

Peachland

34° 59'24" 80° 17'10" Union Marshville 1.08 Lanes Creek 03040105 2 19

167 02125906 Lanes Creek near Polkton 35° 01'33" 80° 13'51" Union Polkton 110a Rocky River 03040105 2 19168 02125951 Lanes Creek near Ansonville 35° 07'49" 80° 11'18" Union Aquadale 133 Rocky River 03040105 2 20

Table 4. Summary of continuous-record gaging stations and partial-record measuring sites in the Rocky River basin in North Carolina where gag

collected — Continued

[mi2, square miles; SR, secondary road; N/A, not applicable; SEO, sewage effluent outfall. Period of record for continuous-record gaging stations (site type 1) is sho

for partial-record sites (site type 2) is shown in water years in which discharge measurements were made. Available records of discharge through the 2002 water yeastations and through the 2001 water year for partial-record measuring sites, except for selected partial-record sites where synoptic discharge measurements were collewater year). Shading indicates the continuous-record gaging stations (red) and partial-record sites (blue) for which low-flow characteristics have been developed]

Site index no. (pl. 1) USGS downstream order number Station name Latitude Longitude County USGS topographic quadrangle Drainage area (mi2

)

Tributary

to

Hydrologic

unit

code

Site type 
50 Low-Flow Characteristics and Profiles for the Rocky River in the Yadkin-Pee Dee River Basin, North Carolina, through 2002 169 02126000 Rocky River near Norwood 35° 08'54" 80° 10'33" Stanly Aquadale 1,372 Pee Dee River 03040105 1 Oc

170 02126088 Hardy Creek tributary above SEO near Aquadale 35° 12'53" 80° 12'27" Stanly Aquadale 0.5a Hardy Creek 03040105 2 19171 02126091 Hardy Creek tributary near Cottonville 35° 12'29" 80° 11'04" Stanly Aquadale 3.09 Hardy Creek 03040105 2 19172 02126101 Hardy Creek near Cottonville 35° 10'48" 80° 10'04" Stanly Aquadale 15.2 Rocky River 03040105 2 19173 02126201 Rocky River at U.S. Highway 52 near Norwood 35° 11'39" 80° 06'49" Stanly Mount Gilead West 1,403 Pee Dee River 03040105 2 20

aApproximate drainage area.bSite now impounded by Lake Don T. Howell (formerly Coddle Creek Reservoir).cLow-flow files for this site indicate the presence of 15 discharge measurements that were made during the 1948–54 water years. However, the files also indica

by presence of diversions and not suitable for low-flow analysis. No information is known about the specific diversions affecting flows at this site during the indicat

Table 4. Summary of continuous-record gaging stations and partial-record measuring sites in the Rocky River basin in North Carolina where gag

collected — Continued

[mi2, square miles; SR, secondary road; N/A, not applicable; SEO, sewage effluent outfall. Period of record for continuous-record gaging stations (site type 1) is sho

for partial-record sites (site type 2) is shown in water years in which discharge measurements were made. Available records of discharge through the 2002 water yea

stations and through the 2001 water year for partial-record measuring sites, except for selected partial-record sites where synoptic discharge measurements were colle

water year). Shading indicates the continuous-record gaging stations (red) and partial-record sites (blue) for which low-flow characteristics have been developed]

Site index no. (pl. 1) USGS downstream order number Station name Latitude Longitude County USGS topographic quadrangle Drainage area (mi2

)

Tributary

to

Hydrologic

unit

code

Site type 
GLOSSARY

Base flow. The contribution of flow to a stream from ground water or spring 

discharge.

Climatic year. A continuous 12-month period during which a complete annual 

cycle occurs. The climatic year typically is from April 1 through March 31, 

designated by the calendar year in which the climatic year begins. For 

example, the 1997 climatic year is the period from April 1, 1997, to 

March 31, 1998. The year begins and ends during the period of increased 

flows so that all flows during a single dry season are included in annual 

values for that year.

Continuous-record gaging station. A site on a stream where continuous 

records of gage height are collected and for which discharge records are 

computed.

Drainage area. The drainage area of a stream at a specified location is the area, 

measured in a horizontal plane, which is enclosed by a drainage divide.

Gage height. The water-surface elevation referenced to an arbitrary gage datum, 

often used interchangeably with the term “stage.”

Low flow. Base flow or sustained fair-weather flow.

Partial-record measuring site. A site on a stream where periodic discharge 

measurements are collected, usually for a period of years. The data collected 

at partial-record sites are often correlated with data at nearby continuousrecord gaging stations to estimate low-flow characteristics at the partialrecord sites.

Recurrence interval. The average interval of time in which the magnitude of an 

extreme event can be expected to be equaled or exceeded once. The primary 

recurrence intervals used in this report are 2 years and 10 years. For example, 

if the 7-day, 10-year low-flow discharge is 5 cubic feet per second (ft3/s), the 

annual minimum average discharge for a 7-consecutive-day period would be 

5 ft3/s or lower, on average, 1 time in 10 years, 5 times in 50 years, or 

10 times in 100 years. Expressed in terms of probability, there is a 10-percent 

probability (inverse of recurrence interval) that the flow will be less than or 

equal to the 7-day, 10-year low-flow discharge in any 1 year. In a similar 

manner, there is a 50-percent probability that the flow will be less than or 

equal to the 7-day, 2-year low-flow discharge in any 1 year. While recurrence 

intervals indicate the average frequency of occurrence for a particular 

hydrologic event, it should be noted that the event could occur more than 

once in a given year, in consecutive years, or not at all during the period 

specified by the recurrence interval.

River mile. A measure of the distance upstream from the mouth of a stream.

Unit flow. Value of flow expressed in units of volume per time per square mile 

of drainage area. In this report, unit flow (sometimes used interchangeably 

with the term “yield”) is expressed as cubic feet per second per square mile 

[(ft3

/s)/mi2].

Water year. The 12-month period October 1 through September 30, designated 

by the calendar year in which the period ends. For example, the 1998 water 

year is the period from October 1, 1997, to September 30, 1998. Average 

discharge and flow-duration data are computed by using the water-year time 

frame.

Zero-flow day. Day in which no flow occurred at a continuous-record gaging 

station and evidenced by a daily mean discharge of zero.