U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2007–5116

Prepared in cooperation with the Mississippi Department of Environmental Quality, 

Office of Pollution Control

Characterization of Water Quality in Unmonitored Streams 

in the Mississippi Alluvial Plain, Northwestern Mississippi, 

May–June 2006
Characterization of Water Quality in 

Unmonitored Streams in the Mississippi 

Alluvial Plain, Northwestern Mississippi, 

May–June 2006

By Jeannie R. Bryson, Richard H. Coupe, and Michael A. Manning

Prepared in cooperation with the Mississippi Department of Environmental Quality, 

Office of Pollution Control

Scientific Investigations Report 2007–5116

U.S. Department of the Interior

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

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

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

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Suggested citation:

Bryson, J.R., Coupe, R.H., and Manning, M.A., 2007, Characterization of water quality in unmonitored streams in the 

Mississippi Alluvial Plain, northwestern Mississippi, May-June 2006: U.S. Geological Survey Scientific Investigations 

Report 2007-5116, 20 p.
iii

Contents

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

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

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

Description of Study Area ...................................................................................................................2

Acknowledgments................................................................................................................................2

Data Collection and Analysis.......................................................................................................................2

Sample Collection and Processing....................................................................................................3

Quality Assurance and Control...........................................................................................................3

Statistical Methods...............................................................................................................................3

Water Quality and Trophic Status of Streams...........................................................................................4

Characterization of Streams Using Indicators of Trophic Classifications............................................4

Summary..........................................................................................................................................................5

References......................................................................................................................................................5

Figures and Tables.........................................................................................................................................7

Appendixes ...................................................................................................................................................17
iv

Figures

1. Map showing location of study area, study sites, and site classification within Nutrient 

Ecoregion X, subecoregion 73, northwestern Mississippi ....................................................8

2. Graph showing relation of 8-year (period of record for gage) mean daily streamflow (1997-

2005) with mean daily streamflow and precipitation between August 1, 2005, and 

August 1, 2006, for streamflow gage on Bogue Phalia near Leland (station 07288650), 

Mississippi .....................................................................................................................................9

3. Graphs showing distribution of selected data among trophic groups at 52 stream sites in 

northwestern Mississippi..........................................................................................................10

4. Graphs showing comparisons and correlation coefficient values (r) between chlorophyll a

and selected constituents and physical properties in order of decreasing 

correlation coefficients .............................................................................................................12

5. Graph showing distribution of dissolved oxygen concentrations by sampling times..................13

6. Maps showing relations of (A) total Kjeldhal nitrogen points to stream trophic group, (B) 

dissolved oxygen points to stream trophic group, (C) turbidity points to stream 

trophic group, and (D) total stream productivity points to stream trophic group............14

Tables

1. Statistical summary of selected physical properties and constituents in water from all 

stream sites combined and within each trophic group, northwestern Mississippi, 

May-June 2006............................................................................................................................15

2. Percentile statistics for indicator physical properties and constituents used to characterize 

streams in northwestern Mississippi ......................................................................................16

3. Point criteria used to characterize stream productivity in northwestern Mississippi.................16

4. Number of northwestern Mississippi streams in each trophic group for each point criteria....16
v

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

micron (μm) 0.00003937 inch (in.)

mile (mi) 1.609 kilometer (km)

millimeter (mm) 0.03937 inch (in.)

Area

square mile (mi2) 2.590 square kilometer (km2) 

Volume

gallon (gal) 3.785 liter (L) 

liter (L) 33.82 ounce, fluid (oz) 

milliliter (mL) 0.0338 ounce, fluid (oz) 

Flow rate

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

foot per second (ft/s) 0.3048 meter per second (m/s)

Pressure

kilopascal (kPa) 6.895 pound-force per square inch 

(lb/in2)

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

°F=(1.8×°C)+32

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

°C=(°F-32)/1.8

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

(NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (μS/cm at 

25 °C).

Concentrations of chemical constituents in water are given either in milligrams per liter (mg/L) 

or micrograms per liter (μg/L).
Abstract 

The Mississippi Department of Environmental Quality is 

required to develop restoration and remediation plans for water 

bodies not meeting their designated uses, as stated in the U.S. 

Environmental Protection Agency’s Clean Water Act section 

303(d). The majority of streams in northwestern Mississippi 

are on the 303(d) list of water-quality limited waters. Agricultural effects on streams in northwestern Mississippi have 

reduced the number of unimpaired streams (reference streams) 

for water-quality comparisons. As part of an effort to develop 

an index to assess impairment, the U.S. Geological Survey 

collected water samples from 52 stream sites on the 303(d) list 

during May-June 2006, and analyzed the samples for nutrients 

and chlorophyll. 

The data were analyzed by trophic group as determined 

by total nitrogen concentrations. Seven constituents (nitrite 

plus nitrate, total Kjeldhal nitrogen, total phosphorus, orthophosphorus, total organic carbon, chlorophyll a, and pheophytin a) and four physical property measurements (specific 

conductance, pH, turbidity, and dissolved oxygen) were 

determined to be significantly different (p < 0.05) between 

trophic groups. Total Kjeldhal nitrogen, turbidity, and dissolved oxygen were used as indicators of stream productivity 

with which to infer stream health. Streams having high total 

Kjeldhal nitrogen values and high turbidity values along with 

low dissolved oxygen concentrations were typically eutrophic 

(abundant in nutrients), whereas streams having low total 

Kjeldhal nitrogen values and low turbidity values along with 

high dissolved oxygen concentrations were typically oligotrophic (deficient in nutrients). 

Introduction 

The Mississippi Department of Environmental Quality 

(MDEQ) is required to develop restoration and remediation 

plans for water bodies not meeting their designated uses, 

as stated in the U.S. Environmental Protection Agency’s 

(USEPA) Clean Water Act (CWA) section 303(d). Waterquality data are necessary to develop restoration and remediation plans for streams in northwestern Mississippi. The majority of these streams are unmonitored due to the geomorphology and inaccessibility of the area (Mississippi Department of 

Environmental Quality, 2004). 

Previous investigations in northwestern Mississippi 

include a pilot study that collected fish, macroinvertebrate, 

water-quality, and habitat data to determine which data were 

most useful as indicators of stream impairment (Rebich and 

others, 2004). In traditional indicator studies, an index (biotic 

or abiotic) is developed using reference streams (unimpaired 

streams), and unmonitored streams are evaluated using the 

index. Agricultural land use in northwestern Mississippi has 

reduced the availability of unimpaired streams that can be 

used to develop an index; therefore, new methods were needed 

to characterize water quality in northwestern Mississippi. As 

part of an effort to develop an index to assess impairment, 

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

MDEQ’s office of Pollution Control, collected and analyzed 

water samples from 52 stream sites in an attempt to determine 

indicators of stream health. 

Biological productivity can be used to assess surfacewater quality and the ecological integrity of a stream. Chlorophyll a is considered an indicator of stream productivity 

because it provides an estimate of algal biomass in the stream 

(Wetzel, 1983). However, chlorophyll a concentrations can 

be dependent on other variables and do not always give a 

complete picture of the stream’s productivity level. Nutrients 

necessary for stream productivity can be harmful in excessive 

concentrations. Nutrient enrichment can cause algal blooms, 

which have many detrimental side effects such as bacterial 

blooms, odor-and-taste problems, and the production of toxins 

that are harmful to humans and wildlife (U.S. Environmental 

Protection Agency, 2000). Previous studies have documented 

the relation between nutrient concentrations and chlorophyll 

a, but few document this relation for streams in the southeastern United States. Carruthers and Wazniak (2005) created 

a water-quality index for the Maryland Coastal Bays using 

chlorophyll a, total nitrogen, total phosphorus, and dissolved 

oxygen as indicators of water quality. Their study found that 

these constituents and physical properties are dependent on the 

overall water quality of the coastal bays and have implications 

on the ability of coastal bays to sustain aquatic life. Montgomery and others (1991) determined that nitrogen availability was the limiting factor in phytoplankton production in 

Charlotte Harbor, Florida. Riskin and others (2003) discussed 

the relation between total nitrogen and total phosphorus to 

Characterization of Water Quality in Unmonitored 

Streams in the Mississippi Alluvial Plain, Northwestern 

Mississippi, May–June 2006

By Jeannie R. Bryson, Richard H. Coupe, and Michael A. Manning
periphyton chlorophyll a and determined that the relation was 

dependent on canopy cover. Paerl (1997) related the introduction of near-surface nitrogen in coastal environments to 

increased eutrophication and algal biomass. Nutrient-algal 

relations are complex and are dependent on other factors such 

as stream flow, stream water temperature, and light penetration 

(turbidity) (U.S. Environmental Protection Agency, 2000).

The USEPA has published several documents providing 

guidance for analyzing nutrient data and developing nutrientalgal relations (U.S. Environmental Protection Agency, 2000, 

2001). The Mississippi Alluvial Plain in northwestern Mississippi is part of USEPA Nutrient Ecoregion X and subecoregion 73 (Mississippi Alluvial Plain). The USEPA uses nutrient 

and chlorophyll data to divide streams in subecoregion 73 

into trophic classifications (oligotrophic, mesotrophic, and 

eutrophic). Trophic refers to the level of available nourishment (nutrients) in a water body. Oligotrophic characterizes 

water with a deficient supply of plant nutrients and usually an 

abundant supply of dissolved oxygen. Mesotrophic characterizes water with a moderate level of plant nutrients. Eutrophic 

characterizes water with a high level of plant nutrients and 

seasonal deficiencies of oxygen. Total nitrogen was used in 

this report to divide streams into their respective trophic classification.

Purpose and Scope 

The purpose of this report is to characterize water quality 

in the Mississippi Alluvial Plain of the Yazoo River Basin 

in northwestern Mississippi during May and June 2006. 

Water samples were collected and analyzed for nutrients and 

chlorophyll a, and physical properties were measured at 52 

unmonitored stream sites. Streams were divided into trophic 

classifications using total nitrogen concentrations and USEPA 

guidance for Nutrient Ecoregion X and subecoregion 73 in an 

attempt to determine indicators of stream health (U.S. Environmental Protection Agency, 2000, 2001). 

Description of Study Area 

More than 50 percent of Mississippi is rural. The largest 

rural region within Mississippi is the northwestern part of 

the State, locally referred to as the “Delta” (U.S. Department 

of Agriculture, 2005). The Delta lies within the Mississippi 

River Alluvial Plain (MRAP) subecoregion 73 and comprises 

about one-half of the Yazoo River Basin in northwestern Mississippi (fig. 1). Agriculture is the dominant land use in the 

Delta. The climate for the MRAP consists of long, hot, humid 

summers with short, mild winters, which allows for a long 

growing season of up to 7 months. The soils in the MRAP 

originate from fertile alluvial/fluvial deposits that are ideal 

for agricultural use. A clay confining layer is present in some 

areas of the MRAP, which provides conditions suitable for 

growing rice as flooded fields help control weed populations. 

This combination of fertile alluvial soil, long growing season, 

and plentiful water supply makes the MRAP an extremely productive agricultural area encouraging the use of all available 

land by agriculture (Mississippi Department of Environmental 

Quality, 2004). 

Acknowledgments 

Data presented in this report were collected as part of 

a cooperative effort with MDEQ. The authors would like to 

acknowledge Chris Awwad, David Burt, Scott Jones, Claire 

Rose, Derek Smith, and Jared Wright of the USGS for their 

help with the field work necessary for this study. 

Data Collection and Analysis

MDEQ randomly selected 58 unmonitored streams in the 

Delta for assessment. Six of the 58 streams were dry on the 

day when sampling was scheduled and, therefore, were not 

sampled. The unsampled streams were all small ephemeral 

creeks that are characterized by seasonal, intermittent flow. 

The remaining 52 streams varied in size from small ephemeral 

streams to larger perennial (continuous flow) streams, most of 

which have been channelized. There was little rainfall during 

the study period as measured at the streamflow gage (fig. 1) on 

Bogue Phalia near Leland (station 07288650) (fig. 2). Because 

of the lack of rainfall, velocity in the streams was subsequently 

low (less than 1.5 ft/s) and the water generally was well mixed 

with respect to stream physical properties. 

Streams were grouped based on their trophic classification using USEPA total nitrogen concentration guidelines 

(U.S. Environmental Protection Agency, 2001). According to 

USEPA guidance for nutrient Ecoregion X, streams with total 

nitrogen concentrations less than 0.7 mg/L are classified as 

oligotrophic, streams with concentrations greater than or equal 

to 0.70 mg/L but less than 1.5 mg/L are classified as mesotrophic, and streams with concentrations greater than or equal 

to 1.5 mg/L are classified as eutrophic. Of the 52 stream sites 

sampled, 6 were oligotrophic, 20 were mesotrophic, and 26 

were eutrophic (fig. 1).

Water-quality data collection was conducted during May 

and June 2006. All streams sampled are currently listed as 

impaired on the CWA Section 303(d) list as designated by 

MDEQ. Samples collected at each stream were analyzed for 

dissolved solids, chloride, nitrite plus nitrate, ammonia, total 

Kjeldhal nitrogen (TKN), total phosphorus, orthophosphorus, 

chlorophyll a, pheophytin a, and total organic carbon. Physical properties of specific conductance, pH, water temperature, 

turbidity, dissolved oxygen, and percent oxygen saturation 

were recorded at each site. Physical properties of chemical 

oxygen demand, and alkalinity were analyzed at the MDEQ 

laboratory. Six replicate samples were collected for chloride, 

nutrients, chlorophyll a, and pheophytin a. 

   Characterization of Water Quality in Unmonitored Streams in the MS Alluvial Plain, Northwestern MS, May-June 2006
Sample Collection and Processing

Water samples were collected according to established 

procedures in the USGS National Field Manual for the Collection of Water-Quality Data (Wilde and Radtke, 1998). 

The samples were depth and width integrated without using 

flow-weighted procedures because of the low gradient of 

the alluvial plain and subsequent low velocities (less than 1 

ft/s) either by wading the stream, by sampling from a bridge 

with a cabled sampler, or by sampling from a boat in remote 

areas. Water samples were analyzed for chloride and nutrient 

concentrations by the MDEQ laboratory in Pearl, Mississippi, 

and water samples were analyzed for chlorophyll a and pheophytin a concentrations by the USGS National Water- Quality 

Laboratory (NWQL) in Lakewood, Colorado. Samples for 

all other constituents were analyzed at the MDEQ laboratory. 

Results of sample analyses for selected constituents are listed 

in appendix 1. 

Sample processing followed guidelines in the MDEQ 

Quality Assurance Project Plan (QAPP) for Mississippi Delta 

Fish IBI Study (Mississippi Department of Environmental 

Quality, 2005), as well as the 2006 Quality Assurance Plan for 

Water-Quality Activities in the USGS Mississippi Water Science Center (Rebich and others, 2006). All sampling equipment was constructed of either Teflon®, glass, or stainless 

steel, and was cleaned before each sample was collected with 

a 0.2-percent solution of nonphosphate detergent, rinsed with 

tap water, and deionized water, allowed to air dry in a dustfree area, and wrapped in either aluminum foil or bagged in 

plastic bags for protection. At each stream location, three 1-L 

Teflon® bottles at minimum were filled from transects across 

the stream and were composited into a Teflon® churn that was 

rinsed onsite. Aliquots were then split into individual bottles 

for whole water analysis. Samples that required filtering were 

filtered onsite using a capsule filter containing a 0.45 μm filter 

and a low-vacuum hand pump. 

Samples for chlorophyll a, and pheophytin a were processed onsite by filtering a measured volume of water through 

a 0.47-mm baked glass-fiber filter held in place by a stainlesssteel filter apparatus and pumped using a low volume (less 

than 20 kPa) vacuum. Prior to filtering the water, the sample 

was thoroughly agitated to suspend the particulates. Various 

volumes (50-150 mL) were filtered for each chlorophyll a

analysis depending on sufficient loading of the filter, which 

was determined by a green or brown color on each filter. 

Filters were folded once, enclosed inside a two-piece Petri 

dish, wrapped in aluminum foil, packed on dry ice, and mailed 

overnight to NWQL. 

Samples for all other constituents were packed on wet 

ice and delivered to the MDEQ laboratory within 48 hours for 

analysis. Physical properties were measured using a multiprobe sonde that was calibrated each morning and rechecked 

at the end of each day. Turbidity was measured using a Hach 

Turbidimenter 2100P. Samples for turbidity were measured 

five times, and the median value was recorded. All of the 

water-quality procedures are described in the QualityAssurance Plan for Water-Quality Activities (Rebich and 

others, 2006).

Quality Assurance and Control

About 10 percent of all samples submitted to each laboratory were replicates. Replicate samples, listed in appendix 

2, are used to assess variability in each data set. The relative 

percentage difference (RPD) was calculated for each replicate 

pair for each constituent using the following equation:

(1)

where Ca equals the concentration of the primary sample, 

and Cb equals the concentration of the replicate sample. The 

average calculated RPD value between replicate samples for 

all constituents analyzed was 9 percent and ranged from 0 

to 66 percent. The average calculated RPD value between 

replicate samples for constituents discussed later in this report 

was 9 percent and ranged between 0 and 40 percent. These 

RPD values indicate that, on average, little variability between 

replicate samples exists. 

The MDEQ laboratory has participated in the Standard 

Reference Sample project of the USGS-Branch of Quality Assurance since September 2002 (information on web, 

accessed September 22, 2006, at http://bqs.usgs.gov/srs/). 

Twice each year (spring and fall), reference samples are sent 

to the MDEQ laboratory for analysis. Nutrient concentrations 

in these reference samples are unknown to the participating 

laboratory. Results from MDEQ analysis are compared to the 

most probable value of the concentration of that particular 

constituent. MDEQ has participated in eight such sampling 

rounds and has successfully measured all constituents.

All USGS personnel in the Mississippi Water Science 

Center who collect water-quality samples participate each year 

in the USGS National Field Quality Assurance Program of the 

USGS Branch of Quality Systems (Stanley and others, 1998). 

Each participant measures the physical properties of water 

in reference samples with known concentrations, but which 

are unknown to the participant. Results determined by the 

participants are compared to the known values to determine 

efficiency of both the participant and the equipment used for 

measuring. USGS Mississippi Water Science Center personnel have participated in the program for several decades, and 

all have successfully completed these tests.

Statistical Methods

Streams were classified by trophic group and then statistically summarized within each group. The Kruskal-Wallis statistical test was used to determine any significant differences 

among median values of constituents for each trophic group 

(Helsel and Hirsch, 1992). The Kruskal-Wallis test is a nonparametric test and was used in this assessment because waterData Collection and Analysis 
quality data usually do not have a normal distribution. A 

probability level of 5 percent (p < 0.05) was chosen as the significant level between at least two of the three trophic groups. 

Tukey’s multiple comparison test (Helsel and Hirsch, 1992) 

was then used to determine which trophic groups differed 

significantly. Boxplots were also created for each constituent 

and physical property measurement to illustrate differences 

between each trophic group. Boxplots are useful for comparing ranges between data sets (Helsel and Hirsch, 1992). In this 

case, they are used to compare the range of values for a single 

constituent or physical property measurement between each 

trophic group. Scatter plots were created to determine correlation coefficients for certain constituents within each trophic 

group. Boxplots were created and the Kruskal-Wallis test was 

performed using S-Plus software. Tukey’s multiple comparison test was perfomed using Statview Statistical Software 

(SAS Insititute, Inc., 1999). 

Water Quality and Trophic Status of 

Streams

Summary statistics for selected measured constituents are 

presented in table 1. Data for each stream are listed in appendix 1. Turbidity values varied over a large range between 7 

and 400 nephelometric turbidity units (NTU). Dissolved-oxygen values ranged from well below saturation (1.6 mg/L) to 

well above saturation (13.6 mg/L). TKN values ranged from 

0.3 to 5.2 mg/L. 

Seven of the constituents and physical property measurements differed significantly (p<0.05) between at least two 

of the three trophic groups and include turbidity, dissolved 

oxygen, TKN, total phosphorus, total organic carbon, chlorophyll a, and pheophytin a (fig. 3). Turbidity, dissolved 

oxygen, and total phosphorus values were statistically different between oligotrophic streams and both mesotrophic and 

eutrophic streams, although values were not statistically different between mesotrophic and eutrophic streams. TKN values 

were statistically different between each trophic group. Total 

organic carbon values were statistically different between 

mesotrophic and eutrophic streams but not between oligotrophic and either mesotrophic or eutrophic streams. Chlorophyll 

a and pheophytin a values were statistically different between 

eutrophic streams and both oligotrophic and mesotrophic 

streams, although values were not statistically different 

between oligotrophic and mesotrophic streams.

Regression analysis was performed to determine correlation coefficients (r) for chlorophyll a and the remaining 

constituents and physical property measurements with statistical significance (p < 0.05). In decreasing order of correlation 

coefficient, they include pheophytin a, TKN, total phosphorus, 

total organic carbon, dissolved oxygen, pH, turbidity, and specific conductance (fig. 4). Pheophytin a is directly related to 

chlorophyll a and, therefore, is not considered as an additional 

dependent variable for productivity. Total phosphorus and 

total organic carbon are components of photosynthetic production and have a similar relation to chlorophyll a and stream 

productivity as nitrogen (TKN) (Drever, 1988). Their correlation coefficients are somewhat lower than TKN and indicate 

that TKN has the stronger relation of the three constituents. 

Dissolved oxygen and turbidity have low correlation coefficients but are considered somewhat dependent variables of 

stream productivity on the basis of their statistical significance 

and statistical differences among at least two trophic groups 

(fig. 3). 

Characterization of Streams Using 

Indicators of Trophic Classifications 

 By using the trophic classification, some interpretation 

is possible with regard to stream productivity. Oligotrophic 

streams potentially are the least productive, whereas eutrophic 

streams potentially are the most productive but possibly the 

most affected by agriculture. Because the trophic classifications are solely based on total nitrogen (TN) concentrations, it 

is important to look at other constituents and stream physical 

properties, as well, to evaluate stream health. 

Stream productivity was characterized further on the 

basis of TKN and potential indicators of stream health–

turbidity and dissolved oxygen. TKN was chosen on the 

basis of its relation to productivity, whereas turbidity and dissolved oxygen were chosen based on their indirect relation to 

stream health. For example, streams with high turbidity limit 

the amount of light penetration, thus potentially decreasing 

productivity; low dissolved oxygen levels can stress or even 

kill aquatic biota whereas very high dissolved oxygen levels 

indicate eutrophic conditions and poor water quality. TKN 

was the only constituent that is statistically significant among 

the three trophic groups and statistically different between 

each of the three trophic groups (fig. 3). TKN also has the 

second highest correlation coefficient with chlorophyll a

after pheophytin a (fig. 4), supporting the use of TKN as a 

relatively strong indicator of stream productivity and water 

quality. Turbidity is higher for mesotrophic and eutrophic 

streams than for oligotrophic streams (fig. 3), in part due to 

increased stream productivity and subsequent plant and algae 

growth or runoff from adjacent agricultural fields. The median 

dissolved oxygen value is higher for oligotrophic streams than 

mesotrophic and eutrophic streams (fig. 3), probably due to 

higher oxygen consumption in productive streams. Dissolved 

oxygen typically is not considered a stable measurement of 

productivity as it varies diurnally in response to sunlight and 

stream productivity changes. For this study, dissolved oxygen 

was relatively stable and independent of the measurement time 

(fig. 5). Measurements made between 1115 and 1300 have the 

largest range, and the median value for measurements made 

between 1515 and 1700 is slightly higher than the median 

values for measurements taken any other time. Measurements 

 Characterization of Water Quality in Unmonitored Streams in the MS Alluvial Plain, Northwestern MS, May-June 2006
of dissolved oxygen overlap for each time period and do not 

indicate a strong dependence on measurement time. 

Table 2 shows the 25th, 50th, and 75th percentile values 

for TKN, turbidity, and dissolved oxygen. These values 

were used to assign points to each stream, with 1 being the 

least productive (less than or equal to 25th percentile for TKN 

and turbidity and greater than or equal to 75th percentile for 

dissolved oxygen) and 3 being the most productive (greater 

than 50th percentile for TKN, turbidity, and dissolved oxygen) (table 3). TKN, dissolved oxygen, and turbidity were 

evaluated independently and then evaluated collectively by 

summing the points from each (fig. 6, table 4). Points are 

indicative of the stream’s productivity (for example, the higher 

the value, the more productive the stream). When each indicator is evaluated independently on the basis of point criteria in 

table 3, there is not a strong relation between trophic group 

and points. However, when the indicators are evaluated collectively (noted in total stream productivity points, table 4), 

there is a definite relation between trophic group and total 

points. That is, the majority of streams for each trophic group 

are within the expected point range. High-range streams 

(7-9 total points) typically are eutrophic streams with comparatively high TKN concentrations, limited light penetration 

(high turbidity), and low-dissolved oxygen concentrations. 

Low-range streams (3 total points) typically are oligotrophic 

streams, which suggest less productivity and, therefore, less 

aquatic life in the stream. These streams have comparatively 

low TKN concentrations, good light penetration (low turbidity), 

and high dissolved-oxygen concentrations. Mid-range streams 

(4-6 total points) typically are mesotrophic and are more likely 

to have a balance between all stream-health indicators. 

Results from this analysis support the use of trophic classification defined by TN concentrations to characterize stream 

productivity in the Mississippi Alluvial Plain. Statistical analysis indicates that stream productivity, as it relates to chlorophyll a, is dependent on TKN, turbidity, and dissolved oxygen. 

A point system that is based on rankings of TKN, turbidity, 

and dissolved oxygen was used to confirm the trophic classification and to further interpret the data. Caution should be used 

in interpreting these data as the trophic classification and point 

system were evaluated on only one sample per stream during 

one season; however, the results are encouraging as the point 

system does produce results in agreement with the USEPA 

guidelines for Nutrient Ecoregion X (U.S. Environmental 

Protection Agency, 2001). 

Summary 

The majority of streams in northwestern Mississippi are 

on the 303(d) list of water-quality limited waters. Agricultural 

effects on streams in northwestern Mississippi have reduced 

the number of unimpaired streams (reference streams) for 

water-quality comparisons. An effort to evaluate the water 

quality of these streams has been initiated by the MDEQ in 

cooperation with the USGS. The USEPA has developed nutrient guidelines for each Nutrient Ecoregion and subecoregion; 

these guidelines were used to group streams by trophic classification. 

Boxplots and regression analysis, as well as other summary statistics, were used to determine indicators of stream 

productivity. Productivity was described by chlorophyll a and 

pheophytin a concentrations measured in the streams. Streams 

with higher concentrations were assumed to have higher productivity. Three indicators of productivity were determined 

from the statistical analysis--TKN, turbidity, and dissolved 

oxygen. TKN was the only constituent that differed significantly between each of the three trophic groups. Turbidity 

was higher for mesotrophic and eutrophic streams than for 

oligotrophic streams, in part due to increased stream productivity and subsequent plant and algae growth or runoff from 

adjacent agricultural fields. The median dissolved-oxygen 

value was higher for oligotrophic streams than for mesotrophic and eutrophic streams, probably due to the higher oxygen 

consumption in more productive streams. 

A point system was developed to characterize streams on 

the basis of productivity using TKN, turbidity , and dissolved 

oxygen. Higher ranked streams typically were eutrophic (high 

productivity), whereas lower ranked streams typically were 

oligotrophic (low productivity). Stream productivity can be 

used to infer stream health and determine which streams have 

a higher risk for algal blooms and fish kills, as well as which 

streams are more likely to sustain aquatic life. 

References

Carruthers, T., and Wazniak, C., 2005, Development of water 

quality index for the Maryland coastal bays in Wazniak, 

C.E. and M.R. Hall [Ed.] Maryland’s coastal bays: Ecosystem health assessment 2004: Maryland Department of 

Natural Resources DNR-12-1202-0009, Tidewater Ecosystem Assessment, Annapolis, MD.

Drever, J.I., 1988, The geochemistry of natural waters: Englewood Cliffs, New Jersey, Prentice Hall, Inc., 437 p. 

Helsel, D.R., and Hirsch, R.M., 1992, Statistical methods in 

water resources: New York, Elsevier Science Publishers, 

552 p.

Mississippi Department of Environmental Quality, 2004, State 

of Mississippi Water Quality Assessment 2004 Section 

305(b) Report Addendum: Mississippi Department of Environmental Quality, 214 p.

Mississippi Department of Environmental Quality, 2005, 

Quality assurance project plan for Mississippi delta fish IBI 

study, 52 p.

References 
Montgomery, R.T., McPherson, B.F., and Emmons, E.E., 

1991, Effects of nitrogen and phosphorous additions on 

phytoplankton productivity and chlorophyll a in a subtropical estuary, Charlotte Harbor, Florida: U.S. Geological Survey Water-Resources Investigations Report 91-4077, 33 p. 

Omernik, J.M., 1987, Ecoregions of the conterminous United 

States: Annuals of the Association of American Geographers, v. 77, p. 118-125. 

Paerl, H.W., 1997, Coastal eutrophication and harmful algal 

blooms--importance of atmospheric deposition and groundwater as “new” nitrogen and other nutrient sources: Limnology and Oceanography, p. 1154-1165

Rebich, R.A., Manning, M.A., and Morris, F., 2006, Quality 

assurance plan for water-quality activities in the Mississippi 

Distict: Unpublished material on file with U.S. Geological 

Survey in Jackson, Mississippi.

Rebich, R.A., Welch, H.L., and Coupe, R.H., 2004, Evaluation 

of water-quality and habitat assessment data to determine 

ranges in stream conditions in the Mississippi River Alluvial Plain of northwestern Mississippi and eastern Arkansas: 

U.S. Geological Survey Water-Resources Investigations 

Report 03-4251, 47p.

Riskin, M.L., Deacon, J.R., Liebman, M.L., and Robinson, 

K.W., 2003, Nutrient and chlorophyll relations in selected 

streams of the New England Coastal Basins in Massachusetts and New Hampshire, June-September 2001: U.S. 

Geological Survey Water-Resources Investigations Report 

03-4191, 16 p.

SAS Institute, Inc., 1999, Statview reference guide: Cary, 

North Carolina, version 8.0, unnumbered pages.

S-PLUS Professional Developer, Insightful Corp., 2005, version 7.0.

Stanley, D.L., Boozer, T.M., and Schroder, L.J., 1998, Summary of the U.S. Geological Survey National Field Quality 

Assurance Program from 1979 through 1997: U.S. Geological Survey Open-File Report 98-392, 11 p.

U.S. Department of Agriculture, 2005, The economics of food, 

farming, natural resources, and rural America--Economic 

Research Services, State Fact Sheets: Mississippi, information available on the Web, accessed 1/15/2007, http://www.

ers.usda.gov/StateFacts/MS.htm.

U.S. Environmental Protection Agency, 2000, Nutrient criteria 

technical guidance manual Rivers and streams: Office of 

Water, EPA 822-B-00-002, variously paged.

U.S. Environmental Protection Agency, 2001, Ambient water 

quality criteria recommendations—information supporting 

the development of State and tribal nutrient criteria—rivers 

and streams in Nutrient Ecoregion X: Office of Water, EPA 

822-B-01-016, variously paged.

Wetzel, R.G., 1983, Limnology: Philadelphia, Pennsylvania, 

Saunders College Publishing, p. 291-295.

Wilde, F.D., and Radtke, D.B., 1998, National field manual for 

the collection of water-quality data: U.S. Geological Survey 

Techniques of Water-Resources Investigations, book 9, variously paginated. 

   Characterization of Water Quality in Unmonitored Streams in the MS Alluvial Plain, Northwestern MS, May-June 2006
FIGURES AND TABLES

FIGURES AND TABLES 
Figure 1. Location of study area, study sites, and site classification within Nutrient Ecoregion X, subecoregion 73, northwestern 

Mississippi. Ecoregions from Omernik (1987)

   Characterization of Water Quality in Unmonitored Streams in the MS Alluvial Plain, Northwestern MS, May-June 2006
Figure 2. Relation of 8-year (period of record for gage) mean daily streamflow (1997-2005) with mean daily streamflow and precipitation between A

2006, for streamflow gage on Bogue Phalia near Leland, Mississippi (station 07288650). Location of gage shown in figure 1. 
Figure 3. Distribution of selected data among trophic groups at 52 stream sites in northwestern Mississippi. Results of KruskalWallis statistical test for each constituent are presented as p in the bottom right corner of each boxplot. Results of Tukey’s multiple 

comparison test are presented as letters above each trophic group within each boxplot. Concentration ranges with different letters 

differ statistically from one another (Helsel and Hirsch, 1992).

10 Characterization of Water Quality in Unmonitored Streams in the MS Alluvial Plain, Northwestern MS, May-June 2006
Figure 3. Distribution of selected data among trophic groups at 52 stream sites in northwestern Mississippi. Results of KruskalWallis statistical test for each constituent are presented as p in the bottom right corner of each boxplot. Results of Tukey’s multiple 

comparison test are presented as letters above each trophic group within each boxplot. Concentration ranges with different letters 

differ statistically from one another (Helsel and Hirsch, 1992). -- Continued

FIGURES AND TABLES 11
Figure 4. Comparisons and correlation coefficient values between chlorophyll a and selected constituents and physical properties in 

order of decreasing correlation coefficients.

12 Characterization of Water Quality in Unmonitored Streams in the MS Alluvial Plain, Northwestern MS, May-June 2006
Figure 5. Distribution of dissolved oxygen concentrations by sampling times.

FIGURES AND TABLES 13
Figure 6. Relations of (A) total Kjeldhal nitrogen points to stream trophic group, (B) dissolved oxygen points to stream trophic group, 

(C) turbidity points to stream trophic group, and (D) total stream productivity points (total Kjeldhal nitrogen plus dissolved oxygen plus 

turbidity) to stream trophic group.

14  Characterization of Water Quality in Unmonitored Streams in the MS Alluvial Plain, Northwestern MS, May-June 2006
Property or constituent No. of samples All data No. of samples Oligotrophic 

Median Mean Min Max Median Mean 

Specific conductance (μS/cm) 52 206 263 69 860 4 165 189 pH (standard units) 52 7.2 -- 6.2 8.5 4 7.8 -- Turbidity (NTU) 52 55 81 7 400 4 13 12 Dissolved oxygen (mg/L) 52 5.5 5.7 1.6 13.6 4 8.6 8.5 Nitrogen, total nitrite-nitrate (mg/L N) 52 0.17 0.30 < 0.02 1.05 4 0.04 0.04 

Nitrogen, total Kjeldahl (mg/L as N) 52 1.6 1.7 0.31 5.16 4 0.4 0.4 

Phosphorus, total (mg/L as P) 52 0.28 0.33 0.03 1.43 4 0.06 0.06 Phosphate, ortho as P (mg/L) 52 0.06 0.10 < 0.01 1.07 4 0.03 0.03 Carbon, total organic (mg/L) 52 9.0 9.5 4.0 22.0 4 8.5 8.0 Chlorophyll a, phytoplankton, (μg/L) 52 15.9 27.2 1.1 116.0 4 3.5 3.6 Pheophytin a, phytoplankton, (μg/L) 52 11.4 17.7 0.1 64.8 4 2.5 2.9 

Mesotrophic group Eutrophic g

Specific conductance (μS/cm) 15 264 276 69 860 33 207 266 pH (standard units) 15 7.3 -- 6.2 8.0 33 7.1 -- Turbidity (NTU) 15 62 111 10 400 33 56 76 Dissolved oxygen (mg/L) 15 4.7 5.1 1.8 8.6 33 5.0 5.6 Nitrogen, total nitrite-nitrate (mg/L N) 15 0.29 0.35 < 0.02 0.99 33 0.16 0.31 

Nitrogen, total Kjeldahl (mg/L as N) 15 1.0 0.9 0.6 1.2 33 1.9 2.2 Phosphorus, total (mg/L as P) 15 0.25 0.23 0.09 0.49 33 0.34 0.41 

Phosphate, ortho as P (mg/L) 15 0.06 0.09 0.03 0.37 33 0.08 0.11 

Carbon, total organic (mg/L) 15 6.0 5.7 4.0 8.0 33 11.0 11.4 

Chlorophyll a, phytoplankton, (μg/L) 15 9.6 10.4 1.6 28.2 33 34.8 37.7 Pheophytin a, phytoplankton, (μg/L) 15 7.7 8.1 1.2 21.8 33 22.3 23.8 

Table 1. Statistical summary of selected physical properties and constituents in water from all stream sites combined and within each trophic Mississippi, May - June 2006[Min, minimum; Max, maximum; NTU, nephelometric turbidity units; mg/L, milligrams per liter; μS/cm, microsiemens per centimeter; μg/L, micrograms per liter; <, less 
Constituent or physical 

property (unit of

measurement)

Percentile concentration

25th

percentile 

50th

percentile 

75th

percentile 

TKN (mg/L) 0.99 1.7 2.0

Turbidity (NTU) 24 55 87

Dissolved oxygen (mg/L) 3.9 5.5 7.2

Table 2. Percentile statistics for indicator constituents or 

physical properties used to characterize streams in northwestern 

Mississippi

[TKN, total Kjeldahl nitrogen; mg/L, milligrams per liter; NTU, nephelometric turbidity units]

Constituent or 

physical

property (unit of 

measurement)

Point criteria

1 2 3

TKN (mg/L) > 25th

percentile 

> 50th percentile ;

> 25th percentile

> 50th

percentile 

Turbidity (NTU) > 25th

percentile 

> 50th percentile ;

> 25th percentile

> 50th

percentile 

Dissolved

oxygen (mg/L)

> 75th

percentile 

> 75th percentile ;

> 50th percentile

< 50th

percentile 

Table 3. Point criteria used to characterize stream productivity in 

northwestern Mississippi

[TKN, total Kjeldahl nitrogen; mg/L, milligrams per liter; NTU, nephelometric turbidity units; >, less than or equal to; >, greater than; <, less than]

Number of streams meeting total Kjeldahl nitrogen criteria Number of streams meeting turbidity criteria

Points Points

Trophic group 1 2 3 Trophic group 1 2 3

Oligotrophic 4 0 0 Oligotrophic 4 0 0

Mesotrophic 7 8 0 Mesotrophic 7 3 5

Eutrophic 3 4 26 Eutrophic 3 11 19

Number of streams meeting dissolved oxygen criteria Total productivity points for all criteria

Points Points

Trophic group 1 2 3 Trophic group 0-3 4-6 7-9

Oligotrophic 4 0 0 Oligotrophic 4 0 0

Mesotrophic 1 5 9 Mesotrophic 0 9 6

Eutrophic 9 7 17 Eutrophic 0 7 26

Table 4. Number of northwestern Mississippi streams in each trophic group for each point criteria.

[Highlighted cells represent the point criteria with the largest number of streams for each trophic group.]

16 Characterization of Water Quality in Unmonitored Streams in the MS Alluvial Plain, Northwestern MS, May-June 2006
APPENDIXES

APPENDIXES 17
Site 

number 

(fig. 

1) 

Station number

Sample 

date 

(month/

day/

year)

Sample 

start 

time 

(24-

hour)

Specific 

conductance, 

field 

(μS/

cm)

pH, 

field 

(standard 

units)

Water 

temperature 

(degrees 

Celsius)

Tubidity 

(NTU)

Dissolved 

oxygen 

(mg/L)

Chemical 

oxygen 

demand

Alkalinity 

as CaCO3

Chloride 

(mg/L as 

Cl)

Nitrite plus 

nitrate 

(mg/ L 

as N)

Amonia 

(mg/L as 

N)

Nitrogen, 

total Kjeldahl (mg/L 

as N)

Total 

phosphorus (mg/L 

as P)

D

1 07279144 5/30/2006 855 229 6.7 22.9 170 4.2 64 107.0 1.1 < 0.02 0.20 2.19 0.67 2 07279836 5/31/2006 830 148 6.5 24.9 40 1.8 26 67.3 2.4 0.04 < 0.10 1.05 0.3 3 07279937 5/31/2006 950 123 6.7 27.4 140 2.0 46 61.4 < 1 < 0.02 0.15 3.34 0.69 4 07279970 5/31/2006 1120 147 6.8 26.0 96 5.0 29 52.4 4.8 0.41 0.32 1.46 0.29 5 07280555 6/13/2006 1245 126 8.1 28.6 16 9.2 10 50.5 7.2 0.05 < 0.10 0.44 0.09 6 07285740 6/12/2006 1335 124 6.6 29.4 14 7.9 < 10 50.9 6.6 0.04 < 0.10 0.36 0.06 7 07285755 6/12/2006 1450 92 6.5 30.2 19 2.2 28 48.0 3.9 < 0.02 < 0.10 1.85 0.25 8 07286006 6/12/2006 1630 302 8.1 36.0 11 9.5 79 141.0 6.4 < 0.02 < 0.10 0.31 0.06 9 07287310 6/12/2006 950 204 7.4 28.7 7 7.4 < 10 93.3 4.2 0.03 < 0.10 0.43 0.03 

10 07287610 5/18/2006 1450 69 6.3 22.1 400 6.2 29 23.0 2.4 0.50 0.21 0.87 0.38 11 07288185 5/24/2006 915 645 7.6 26.6 72 4.4 12 169.0 62.6 < 0.02 0.33 2.55 0.28 12 07288365 6/14/2006 830 635 7.7 26.9 60 8.5 35 242.0 46.2 0.04 < 0.10 2.51 0.42 13 07288595 6/14/2006 1025 514 8.0 28.0 62 7.2 40 173.0 48.7 0.24 < 0.10 3.15 0.27 14 07288600 5/22/2006 1430 170 7.1 25.5 200 7.2 25 47.7 12.6 0.52 0.15 1.97 0.41 15 07288643 5/23/2006 915 95 7.2 23.6 82 7.1 22 38.0 1.7 0.37 < 0.10 1.10 0.25 16 07288646 5/23/2006 1015 135 7.1 25.4 22.5 4.9 35 54.2 1.9 0.16 < 0.10 1.32 0.21 17 07288798 6/20/2006 1100 354 7.2 28.6 54 3.3 25 154.0 13.6 < 0.02 < 0.10 1.70 0.17 18 07288938 6/21/2006 1100 339 7.3 29.0 14 3.3 17 132.0 15.8 < 0.02 < 0.10 0.96 0.1 19 322908090540900 6/21/2006 1030 384 7.3 29.0 17 2.2 14 167.0 8.8 < 0.02 < 0.10 0.95 0.1 20 323417090431500 5/17/2006 1100 310 7.4 21.6 62 5.8 19 148.0 4.4 0.19 < 0.10 1.18 0.27 

21 323433090472700 6/21/2006 1200 349 7.5 29.2 13 4.4 15 127.0 18.3 < 0.02 < 0.10 0.96 0.11 22 324909090421200 5/18/2006 1315 78 6.3 20.0 340 4.1 22 28.8 2.3 0.57 0.24 0.99 0.33 23 325222090251400 5/19/2006 830 105 6.9 20.3 27 5.9 59 48.3 2.0 0.03 < 0.10 1.80 0.45 24 325901090465500 5/18/2006 1030 86 6.2 20.6 360 3.6 19 23.2 2.1 0.57 0.29 0.95 0.37 25 331207090244100 5/22/2006 1030 130 6.8 25.8 33 6.8 47 40.6 4.4 < 0.02 < 0.10 1.79 0.21 

Appendix I. Summary of surface-water analytical results from the U.S. Geological Survey National Water Quality Laboratory and the Mississippi DeQuality laboratory for stream sites in northwestern Mississippi, May-June 2006[TKN, total Kjeldahl nitrogen; μS/cm, microsiemens per centimeter at 25 degrees Celsius; NTU, nephelometric turbidity units; mg/L, milligrams per liter; CaCO3, calcium carb
Site 

number 

(fig. 

1) 

Station number

Sample 

date 

(month/

day/

year)

Sample 

start 

time 

(24-

hour)

Specific 

conductance, 

field 

(μS/

cm)

pH, 

field 

(standard 

units)

Water 

temperature 

(degrees 

Celsius)

Tubidity 

(NTU)

Dissolved 

oxygen 

(mg/L)

Chemical 

oxygen 

demand

Alkalinity 

as CaCO3

Chloride 

(mg/L as 

Cl)

Nitrite plus 

nitrate 

(mg/ L 

as N)

Amonia 

(mg/L as 

N)

Nitrogen, 

total Kjeldahl (mg/L 

as N)

Total 

phosphorus (mg/L 

as P)

D

26 332844090370800 5/22/2006 1230 122 7.0 22.5 220 5.4 32 39.0 4.8 0.83 < 0.10 1.79 0.37 27 333328090554800 5/23/2006 1445 585 7.7 29.9 48 6.6 41 152.0 10.2 0.91 1.02 5.16 0.16 28 333615090061800 6/12/2006 1225 140 7.2 29.1 10 7.0 15 60.9 4.9 0.13 < 0.10 0.64 0.09 29 333844090515400 5/23/2006 800 96 7.8 26.3 67 8.6 27 41.8 1.7 0.21 < 0.10 1.06 0.27 30 334324090262400 5/25/2006 1245 570 8.1 30.4 17 13.6 < 10 191.0 29.8 1.05 0.80 2.04 0.09 31 334527090350400 6/13/2006 1500 336 7.0 26.5 28 4.0 39 122.0 7.3 < 0.02 < 0.10 1.49 0.16 32 334747090285000 5/25/2006 1100 424 7.3 24.7 89 6.1 12 167.0 7.5 0.99 0.17 0.68 0.13 33 335100090225500 5/24/2006 1530 103 7.0 31.6 100 6.6 37 43.4 2.0 0.15 < 0.10 1.37 0.34 34 335100090225700 5/24/2006 1345 188 7.5 30.2 150 8.4 46 81.3 4.4 < 0.02 < 0.10 1.92 0.38 35 335105090415300 5/24/2006 745 435 7.6 25.4 84 3.9 55 195.0 15.6 < 0.02 < 0.10 3.3 1.43 36 335458090287000 5/25/2006 945 131 6.8 26.8 73 1.6 56 61.0 2.0 < 0.02 < 0.10 1.84 0.74 37 335604090075800 6/13/2006 900 264 6.7 23.6 25 4.7 19 113.0 13.7 0.09 < 0.10 0.73 0.15 38 335737090270100 5/24/2006 1200 120 8.4 29.0 56 11.8 48 58.8 1.6 < 0.02 < 0.10 1.71 0.75 39 335749090273300 5/24/2006 1100 115 6.9 26.4 50 3.2 29 48.0 1.9 0.07 0.64 1.7 0.77 40 340030090155300 6/13/2006 955 365 7.6 25.7 30 5.0 < 10 168.0 13.2 0.06 < 0.10 1.31 0.3 41 340157090071200 6/13/2006 1115 282 7.1 24.7 81 2.3 39 130.0 12.3 0.05 0.16 2.26 0.35 42 340423090210800 5/25/2006 830 150 6.7 25.3 180 3.9 29 66.7 4.2 0.27 0.65 2.13 0.83 43 340507090345400 6/13/2006 1700 497 8.0 28.4 56 8.4 21 212.0 20.3 0.49 0.22 1.02 0.13 44 341341090413100 6/12/2006 1200 305 7.3 29.7 21 5.6 28 137.0 9.6 0.03 < 0.10 1.44 0.22 45 341508090302500 6/12/2006 1545 265 8.5 30.5 49 7.6 50 113.0 14.2 < 0.02 < 0.10 2.37 0.46 

46 341556090243100 6/13/2006 800 860 7.4 21.2 86 2.6 21 210.0 134.0 0.05 < 0.10 0.91 0.49 47 341701090113300 5/31/2006 1245 307 7.6 28.4 35 11.1 42 120.0 8.8 0.17 1.11 3.77 0.17 48 342328090273700 6/12/2006 1430 163 7.6 30.7 29 5.7 13 73.2 4.5 0.06 0.14 1.46 0.16 49 343553090165700 5/30/2006 1200 333 7.2 26.6 18 3.9 43 146.0 10.7 0.75 0.46 2.02 0.12 50 344246090263600 5/30/2006 1605 207 7.3 30.3 33 3.3 75 100.0 2.3 < 0.02 < 0.10 2.27 0.65 

51 344251090233100 5/30/2006 1445 160 7.0 31.0 77 4.6 41 76.5 1.3 0.03 0.31 1.84 0.3 52 344516090164400 5/30/2006 1030 242 6.9 25.2 180 5.7 39 106.0 7.7 < 0.02 0.10 2.18 0.48 

Appendix I. Summary of surface-water analytical results from the U.S. Geological Survey National Water Quality Laboratory and the Mississippi DeQuality laboratory for stream sites in northwestern Mississippi, May-June 2006--Continued
Site 

number 

(fig. 

1) 

Station number

Date 

(month/

day/year)

Sample 

start 

time 

(24-

hour)

Chemical 

oxygen 

demand 

(mg/L)

Alkalinity 

as CaCO3

Chloride 

(mg/L as 

Cl)

Nitrite 

plus nitrate (mg/ 

L as N)

Ammonia 

(mg/L as 

N)

Nitrogen, 

total 

Kjeldahl 

(mg/L as 

N)

Total 

phosphorus 

(mg/L as 

P)

Dissolved 

orthophosphorus (mg/L 

as P)

Co

(

5 7280555 6/13/2006 1245 10 50.5 7.2 0.05 < 0.10 0.44 0.09 0.03 5 7280555 6/13/2006 1300 12 49.5 6.6 0.05 < 0.10 0.53 0.10 0.03 8 7286006 6/12/2006 1630 79 141.0 6.4 < 0.02 < 0.10 0.31 0.06 0.05 8 7286006 6/12/2006 1650 < 10 145.0 6.7 < 0.02 < 0.10 0.45 0.05 0.04 

21 323433090472700 6/21/2006 1200 15 127.0 18.3 < 0.02 < 0.10 0.96 0.11 0.05 21 323433090472700 6/21/2006 1201 14 125.0 18.2 < 0.02 < 0.10 0.94 0.11 0.05 23 325222090251400 5/19/2006 830 59 48.3 2.0 0.03 < 0.10 1.80 0.45 0.05 23 325222090251400 5/19/2006 845 59 48.5 1.8 < 0.02 < 0.10 2.20 0.44 0.06 27 333328090554800 5/23/2006 1445 41 152.0 10.2 0.91 1.02 5.16 0.16 0.08 27 333328090554800 5/23/2006 1450 37 153.0 9.8 0.92 0.99 5.17 0.18 0.09 51 344251090233100 5/30/2006 1445 41 76.5 1.3 0.03 0.31 1.84 0.30 0.05 51 344251090233100 5/30/2006 1500 40 78.5 1.6 0.03 0.31 1.41 0.30 0.05 

Appendix 2. Quality assurance data from the U.S. Geological Survey National Water Quality Laboratory and the Mississippi Department of Envioronfor water-quality samples from stream sites in northwestern Mississippi, May-June 2006[TKN, total Kjeldahl nitrogen; CaCO3; calcium carbonate; mg/L, milligrams per liter; ug/L, micrograms per liter; <, less than]
Bryson, Jeannie R., Coupe, Richard H., and Manning, Michael A.—Characterization of Water Quality in Unmonitored Streams in the Mississippi Alluvial Plain, 

Northwestern Mississippi, May-June 2006—U.S. Geological Survey Scientific Investigations Report 2007-5116

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